Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “dual evolution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2003

The relationship of brain and cervical cord volume to disability in clinical subtypes of multiple sclerosis: a three-dimensional MRI study.

OBJECTIVES: Brain and cervical cord volume is a potentially valuable index marker of irreversible pathological processes in multiple sclerosis (MS). Volume in both brain and cervical cord regions in the same patients has only been investigated in a small number of subjects. We aimed at measuring volume in different parts of the central nervous system, and its relationship with clinical measures, in relapsing-remitting (RR) and secondary progressive (SP) MS patients. MATERIAL AND METHODS: Conventional dual echo and three-dimensional (3-D) magnetization prepared rapid acquisition gradient echo imaging was performed on 97 (49 RR and 48 SP) MS patients, and on 31 age- and gender-matched healthy controls. The volumes of the supratentorial brain, lateral ventricles, brainstem, cerebellum and upper cervical cord (UCC) were determined on 3-D magnetic resonance imaging. RESULTS: RR MS patients had significantly smaller supratentorial brain (P=0.002) and larger lateral ventricles (P=0.047) compared with controls, but no differences were found for cerebellum, brainstem and UCC volumes. Significantly smaller supratentorial brain (P<0.0001), cerebellum (P=0.007), brainstem (P=0.0004) and UCC (P<0.0001) volumes, and larger lateral ventricles (P<0.0001) were observed in SP MS patients than in controls. In RR MS, T2-lesion volume correlated with supratentorial (r=-0.46, P=0.0009), lateral ventricular (r=0.65, P<0.0001), cerebellar (r=-0.42, P=0.003) and brainstem (r=-0.35, P=0.01) volumes, but not with UCC volume (r=-0.18, P=0.22). In SP MS, apart from lateral ventricular volume (r=0.52, P=0.0002), none of the estimated structural volumes correlated with T2-lesion volume. The UCC volume correlated with brainstem volume in both RR MS (r=0.35, P=0.016) and SP MS (r=0.38, P=0.007). Multiple regression analysis showed that supratentorial brain volume in RR group, and UCC volume in SP group, were single significant contributors (P=0.01 and 0.04, respectively) to the Expanded Disability Status Scale of all factors entered into the regression model. CONCLUSION: Atrophy is confined to the supratentorial compartment early in the disease course corresponding to the RR stage, but becomes more pronounced in the brain and cervical spinal cord in the SP phase. The estimate of cervical cord volume for SP MS is relevant to functional disability and may be helpful in monitoring MS evolution in the progressive form of disease.

Adult↗
PubMed1999

Dual modes of the carbon cycle since the Last Glacial Maximum.

The most conspicuous feature of the record of past climate contained in polar ice is the rapid warming which occurs after long intervals of gradual cooling. During the last four transitions from glacial to interglacial conditions, over which such abrupt warmings occur, ice records indicate that the CO2 concentration of the atmosphere increased by roughly 80 to 100 parts per million by volume. But the causes of the atmospheric CO2 concentration increases are unclear. Here we present the stable-carbon-isotope composition (delta 13 CO2) of CO2 extracted from air trapped in ice at Taylor Dome, Antarctica, from the Last Glacial Maximum to the onset of Holocene times. The global carbon cycle is shown to have operated in two distinct primary modes on the timescale of thousands of years, one when climate was changing relatively slowly and another when warming was rapid, each with a characteristic average stable-carbon-isotope composition of the net CO2 exchanged by the atmosphere with the land and oceans. delta 13 CO2 increased between 16.5 and 9 thousand years ago by slightly more than would be estimated to be caused by the physical effects of a 5 degrees C rise in global average sea surface temperature driving a CO2 efflux from the ocean, but our data do not allow specific causes to be constrained.

Antarctic Regions↗
PubMed2004

Genotypic resistance and HIV-1 subtype in Brazilian children on dual and triple combination therapy.

BACKGROUND: Antiretroviral therapy is provided by the Brazilian Ministry of Health to eligible HIV-infected individuals. Based on clinical and immunological classification, the Brazilian guidelines recommend dual or triple therapy for children. However, the development of drug-resistant strains or poor adherence to therapy could impact the efficacy of this approach. OBJECTIVES: We examined relationships between RNA levels, CD4+ T-cell counts, treatment history, and the prevalence of drug-resistant variants in a cohort of HIV-1-infected children in Rio de Janeiro, Brazil. STUDY DESIGN: Direct sequencing of reverse transcriptase and protease genes from plasma was performed. Virologic and CD4+ T-cell counts responses to therapy were assessed by changes in HIV-1 RNA levels and CD4+ T-cell counts from baseline. RESULTS: Thirty-seven patients were receiving dual therapy and 38 were on triple therapy at enrollment, segregated by antiretroviral history. Both groups had a higher increase in CD4+ T cell counts and a lower viral load in pre-treatment antiretroviral-naïve subjects. Notably, there was a direct correlation between the higher frequencies of drug-resistance mutations and cross-resistance with previous usage of antiretroviral (ARV) therapy in both groups. Non-B subtypes isolates were found in 21.3% of samples. A smaller increase in CD4+ T cell counts was found between non-B subtypes when compared to B-subtypes. CONCLUSIONS: These results suggest that less immunological recovery and a higher number of mutations related to drug resistance were associated with previous usage of ARV and consequent higher time under drug selective pressure in these HIV-infected Brazilian children. These facts suggest the preferential use of triple drug combination as first line regimen in children.

Adolescent↗
PubMed1995

Latent inhibition in drug naive schizophrenics: relationship to duration of illness and dopamine D2 binding using SPET.

The dual aims of the study were (1) to examine the effect of neuroleptic medication on the expression of latent inhibition (LI) by studying LI in drug naive schizophrenic patients, and (2) to investigate the relationship between LI and dopamine D2 receptor binding in the basal ganglia using single photon emission tomography (SPET). Subjects constituted a sub-set of patients investigated in a major study of in vivo D2 receptor binding in schizophrenia (Pilowsky et al., 1993). Striatal D2 receptor binding was assessed in 15 neuroleptic naive schizophrenic patients and 13 healthy volunteers. The performance of subjects on a within-subject auditory latent inhibition paradigm was also assessed. There was found to be no significant difference in LI between schizophrenic patients and normal controls, both groups showing a strong within-subject LI effect. There was also found to be no association between LI and dopamine D2 receptor binding in either the left or the right basal ganglia. This lack of association indicates that LI is not directly related to post-synaptic D2 receptor levels in the striatum. LI was, however, found to be correlated with duration of illness in the schizophrenic group. Patients with a relatively short duration of illness (< 12 months) tended to show reversed, or absent, LI whereas patients with a longer illness duration (> 12 months) showed intact LI. The effect on LI of duration of illness is consistent with previous findings that LI is disrupted specifically in acute, but not chronic, schizophrenia. Previous studies have assumed that this pattern of results is due to the stabilising effect of long-term neuroleptic medication. The present findings in a sample of neuroleptic naive schizophrenic patients indicate that this is unlikely to be the case. Rather, it appears that the reinstatement of LI in schizophrenic patients over time is due to a factor(s) intrinsic to the evolution of the schizophrenic illness.

Adolescent↗
PubMed1997

[Effectiveness and tolerance of tramadol in cancer pain. A comparative study with respect to buprenorphine].

Opioid analgesics represent one of the most important tools in a sequential pharmacological approach to oncological pain relief. They are recommended by the WHO when nonsteroidal anti-inflammatory drugs (NSAIDs) no longer provide adequate analgesia. However, the use of opioids is limited because of their numerous and often severe adverse effects. This aspect of opioids has motivated continuous research projects aimed at discovering drugs that can provide maximum pain relief but with improved tolerability. Tramadol is a new, centrally acting analgesic with a dual mechanism of action. It shows a selective interaction with mu receptors, which are responsible for nociception, and has weak pharmacodynamic activity on other opioid receptors. At the same time, it acts synergistically on neuroamine transmission by inhibiting synaptic noradrenaline (norepinephrine) reuptake and inducing intrasynaptic serotonin (5-hydroxytryptamine; 5-HT) release. From a pharmacokinetic standpoint, tramadol offers high bioavailability, with similar patterns after oral or parenteral administration (half-life 5 to 7 hours, time to peak plasma concentration 3.1 hours, and approximately 20% plasma protein binding). Although the efficacy of tramadol is comparable to that of other drugs with similar modes of action, the incidence of side effects such as constipation and respiratory depression is lower. The frequency of euphoria and dysphoria is negligible, resulting in little risk of abuse or dependence. It therefore seemed appropriate to further investigate the efficacy and tolerability of tramadol, defined as having only weak potency, in comparison with a widely used opioid, in oncological pain. Buprenorphine was selected as an opioid with a potency equivalent to half that of morphine, but with tolerability that is partially limited by the fact that it frequently gives rise to adverse reactions considered typical of stronger opioids. To compare the analgesic effect and tolerability of tramadol and buprenorphine, 60 patients (44 men, 16 women; average age 61.4 years), all presenting with advanced tumours, were treated orally in a controlled crossover trial with randomised sequences. Patients took both drugs, each for a week, with a 24-hour washout period between treatments. Tramadol was prescribed at the daily dose of 300mg, orally, and buprenorphine at 0.6 mg/day, as a sublingual preparation. Assessments were made of Karnofsky performance status and severity of pain before and during the 4 hours after taking the 2 drugs. Each patient also completed a daily diary recording the severity of pain 1 hour after the dose, the evolution of pain during the day and its severity compared with that on the previous day. They also assessed the duration and quality of sleep. The Karnofsky index changed little with either treatment, but all other variables showed worthwhile improvement, indicating the significant analgesic effect of both drugs. Buprenorphine and tramadol had a similar analgesic effect, although the improvement with the test drug was significant within 1 hour of administration (p < 0.05 compared with baseline) and more marked (p < 0.05 on day 2 compared with buprenorpine). At the end of tramadol treatment, sleep had also improved, both quantitatively and qualitatively (both p < 0.05). The final assessment was significantly in favour of tramadol as regards efficacy (p < 0.05) and patient acceptability (p < 0.01). Thus, tramadol was better tolerated than buprenorphine, and caused fewer and milder adverse reactions. Only 1 patient discontinued tramadol, compared with 18 using reference therapy. Tramadol, although theoretically less potent, nevertheless brought about as much pain relief as the comparator opioid. In conclusion, for this class of drug, tramadol provides an excellent balance between efficacy and tolerability, confirming preliminary studies.

Aged↗
PubMed2006

Micro- and macroevolutionary decoupling of cichlid jaws: a test of Liem's key innovation hypothesis.

The extent to which elements of functional systems can change independently (modularity) likely influences the diversification of lineages. Major innovations in organismal design, like the pharyngeal jaw in cichlid fishes, may be key to a group's success when they relax constraints on diversification by increasing phenotypic modularity. In cichlid fishes, pharyngeal jaw modifications that enhanced the ability to breakdown prey may have freed their oral jaws from serving their ancestral dual role as a site of both prey capture and prey processing. This functional decoupling that allowed the oral jaws to become devoted solely to prey capture has been hypothesized to have permitted the two sets of cichlid jaws to evolve independently. We tested the hypothesis that oral and pharyngeal jaw mechanics are evolutionarily decoupled both within and among Neotropical Heroine cichlids. In the trophically polymorphic species Herichthys minckleyi, molariforms that exhibit enlarged molarlike pharyngeal jaw teeth were found to have approximately 400% greater lower jaw mass compared to H. minckleyi with the alternative papilliform pharyngeal morphology. However, oral jaw gape, lower jaw velocity ratios, anterior jaw linkage mechanics, and jaw protrusion did not differ between the morphotypes. In 40 other Heroine species, there was a weak correlation between oral jaw mechanics and pharyngeal jaw mass when phylogenetic history was ignored. Yet, after expansion of the cytochrome b phylogeny for Heroines, change in oral jaw mechanics was found to be independent of evolutionary change in pharyngeal jaw mass based on independent contrasts. Evolutionary decoupling of oral and pharyngeal jaw mechanics has likely played a critical role in the unparalleled trophic diversification of cichlid fishes.

Animals↗
PubMedDate not supplied

Degree of remaining C=C bonds, polymerization shrinkage and stresses of dual-cured core build-up resin composites.

This study measured the degree of remaining C=C bonds (RDB), linear polymerization shrinkage (LPS) and polymerization stresses (PS) of dual-cured resin composite build-up materials using a variety of light exposure scenarios. Four commercially available materials were used: Bis-Core, FluoroCore, Build-it! and Permalute. The RDB was measured using FTIR spectroscopy, and custom-made devices were used to measure LPS and PS values. Data were obtained using three different modes of photoactivation: NLC (No Light-Curing); ILC (Immediate Light-Curing, where 60 second light-curing was applied at the start of the observation period); and DLC (Delayed Light-Curing, where 60-second light-curing was applied 10 minutes from the start of the observation period). Statistical evaluation of the data at the end of the 13-minute observation period was performed with two-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) Test (p=0.05) and simple linear regression. Differences in the development of LPS and PS during the 13 minutes were studied using mathematical calculus. Bis-Core presented the highest RDB and Permalute the lowest when ILC was applied, while no differences were found between Build-it! and FluoroCore and NLC and DLC increased RDB for FluoroCore and Permalute compared to ILC; whereas, no differences were noted for Build-it! and Bis-Core. Using DLC, a decrease in RDB was found only for Build-it! FluoroCore and Permalute exhibited a reduction in LPS and PS using NLC relative to ILC. No differences in LPS and PS values were detected for the materials Bis-Core and Build-it! when subjected to NLC or DLC, compared to ILC. Simple linear regression showed that only the two polymerization shrinkage properties studied were highly correlated (LPS-PS r2=0.85). The RDB rate was not correlated with either polymerization shrinkage properties (RDB-LPS r2=0.40; RDB-PS r2=0.57). A study of the evolution of the real-time curves of percentage values of LPS and PS showed that these properties evolved in a similar exponential mode and that, most often, there was a delay in the development of PS.

Carbon↗
PubMed2002

Impact of estradiol supplementation on dual peptidyl drive of GH secretion in postmenopausal women.

As an indirect probe of estrogen-regulated hypothalamic somatostatin restraint, the present study monitors the ability of short-term oral E2 supplementation to modulate GH secretion during combined continuous stimulation by recombinant human GHRH [GHRH-(1-44)-amide] and the potent and selective synthetic GH-releasing peptide, GHRP-2. According to a simplified tripeptidyl model of GH neuroregulation, the effects of estrogen in this dual secretagogue paradigm should mirror alterations in endogenous somatostatinergic signaling. To this end, seven healthy postmenopausal women underwent frequent (10-min) blood sampling for 24 h during simultaneous i.v. infusion of GHRH and GHRP-2 each at a rate of 1 microg/kg x h on d 10 of randomly ordered placebo or 17beta-estradiol (E2) (1 mg orally twice daily) replacement. Serum GH concentrations (n = 280/subject) were assayed by chemiluminescence. The resultant GH time series was evaluated by deconvolution analysis, the approximate entropy statistic, and cosine regression to quantitate pulsatile, entropic (feedback-sensitive), and 24-h rhythmic GH release, respectively. Statistical comparisons revealed that E2 repletion increased the mean (+/- SEM) serum E2 concentration to 222 +/- 26 pg/ml from 16 +/- 1.7 pg/ml during placebo (P < 0.001) and suppressed the serum LH by 48% (P = 0.0033), serum FSH by 64% (P < 0.001), and serum IGF-I by 44% (P = 0.021). Double peptidyl secretagogue stimulation elevated mean 24-h serum GH concentrations to 8.1 +/- 1.0 microg/liter (placebo) and 7.7 +/- 0.89 microg/liter (E2; P = NS) and evoked prominently pulsatile patterns of GH secretion. No primary measure of pulsatile or basal GH release was altered by the disparate sex steroid milieu, i.e. GH secretory burst amplitudes of 0.62 +/- 0.93 (placebo) and 0.72 +/- 0.16 (E2) microg/liter x min, GH pulse frequencies of 27 +/- 1.8 (placebo) and 23 +/- 1.9 (E2) events/24 h, GH half-lives of 12 +/- 0.74 (placebo) and 15 +/- 4.5 (E2) min, and basal (nonpulsatile) GH secretion 70 +/- 22 (placebo) and 57 +/- 18 (E2) ng/liter x min. The approximate entropy (ApEn) of serial GH release [1.297 +/- 0.061 (placebo) and 1.323 +/- 0.06 (E2)] and the mesor (cosine mean), amplitude, and acrophase (time of the maximum) of 24-h rhythmic GH secretion were likewise invariant of estrogen supplementation. Estimated statistical power exceeded 90% for detecting significant (P < 0.05) within-subject changes exceeding 30-50% in the mean serum GH concentration, GH ApEn, or GH mesor. In contrast, ApEn analysis of the evolution of successive GH secretory burst-mass values over 24 h disclosed that E2 replacement disrupts the serial regularity of pulsatile GH output (elevates the ApEn ratio) during combined GHRH/GHRP-2 stimulation (P = 0.004). In summary, short-term elevation of serum E2 concentrations in postmenopausal individuals into the midfollicular phase range observed in young women does not significantly alter 24-h basal, pulsatile, entropic, or nyctohemeral GH secretion monitored under continuous combined drive by GHRH and GHRP-2. As E2 repletion without enforced GHRH/GHRP-2 stimulation augments each of the foregoing regulated facets of GH release, we infer that one or both of the infused peptidyl secretagogues may itself participate in E2's short-term amplification of GH secretion in postmenopausal individuals. Estrogen's disruption of the orderliness of sequential GH pulse-mass values during fixed GHRH/GHRP-2 feedforward would be consistent with a subtle reduction in the release and/or actions of hypothalamic somatostatin or an (unexpected) direct pituitary action of the sex steroid. Whether comparable dynamics mediate the effects of endogenous estrogen on the GH axis in premenopausal women or pubertal girls is not known.

Aged↗
PubMed1999

The ecological role of the prehensile tail in white-faced capuchins (Cebus capucinus).

Prehensile tails appear to have evolved at least twice in platyrrhine evolution. In the atelines, the tail is relatively long and possesses a bare area on the distal part of its ventral surface that is covered with der-matoglyphs and richly innervated with Meissner's corpuscles. In contrast, the prehensile tail of Cebus is relatively short, fully haired, and lacks specialized tactile receptors. Little is currently known regarding tail function in capuchins, and whether their prehensile tail serves a greater role in feeding or traveling. In this paper we examine patterns of positional behavior, substrate preference, and tail use in wild white-faced capuchins (Cebus capucinus) inhabiting a wet tropical forest in northeastern Costa Rica. Observational data were collected over the course of 3 months on adult capuchins using an instantaneous focal animal time sampling technique. Differences in the frequency and context of tail use, and the estimated amount of weight support provided by the tail relative to other appendages during feeding/foraging and traveling were used as measures of the ecological role of this specialized organ in capuchin positional behavior. During travel, quadrupedal walking, leaping, and climbing dominated the capuchin positional repertoire. The capuchin tail provided support in only 13.3% of travel and was principally employed during below branch locomotor activities. In contrast, tail-assisted postures accounted for 40.6% of all feeding and foraging records and occurred primarily in two contexts. The tail was used to suspend the individual below a branch while feeding, as well as to provide leverage and weight support in above-branch postures associated with the extraction of prey from difficult to search substrates. A comparison of tail use in Cebus, with published data on the atelines indicates that both taxa possess a grasping tail that is capable of supporting the animal's full body weight. In capuchins and howling monkeys, the tail appears to be used more frequently and serves a greater weight-bearing role during feeding than during traveling. In Ateles, and possibly Brachyteles, and Lagothrix, however, the prehensile tail serves a dual role in both feeding and forelimb suspensory locomotion. Additional relationships between white-faced capuchin feeding, positional behavior, extractive foraging techniques, and prehensile tail use are discussed.

Animals↗
PubMed2004

Crystal structure of a bacterial type III polyketide synthase and enzymatic control of reactive polyketide intermediates.

In bacteria, a structurally simple type III polyketide synthase (PKS) known as 1,3,6,8-tetrahydroxynaphthlene synthase (THNS) catalyzes the iterative condensation of five CoA-linked malonyl units to form a pentaketide intermediate. THNS subsequently catalyzes dual intramolecular Claisen and aldol condensations of this linear intermediate to produce the fused ring tetrahydroxynaphthalene (THN) skeleton. The type III PKS-catalyzed polyketide extension mechanism, utilizing a conserved Cys-His-Asn catalytic triad in an internal active site cavity, is fairly well understood. However, the mechanistic basis for the unusual production of THN and dual cyclization of its malonyl-primed pentaketide is obscure. Here we present the first bacterial type III PKS crystal structure, that of Streptomyces coelicolor THNS, and identify by mutagenesis, structural modeling, and chemical analysis the unexpected catalytic participation of an additional THNS-conserved cysteine residue in facilitating malonyl-primed polyketide extension beyond the triketide stage. The resulting new mechanistic model, involving the use of additional cysteines to alter and steer polyketide reactivity, may generally apply to other PKS reaction mechanisms, including those catalyzed by iterative type I and II PKS enzymes. Our crystal structure also reveals an unanticipated novel cavity extending into the "floor" of the traditional active site cavity, providing the first plausible structural and mechanistic explanation for yet another unusual THNS catalytic activity: its previously inexplicable extra polyketide extension step when primed with a long acyl starter. This tunnel allows for selective expansion of available active site cavity volume by sequestration of aliphatic starter-derived polyketide tails, and further suggests another distinct protection mechanism involving maintenance of a linear polyketide conformation.

Acyltransferases↗
PubMed2006

Structure, expression, and functional analysis of the hexokinase gene family in rice (Oryza sativa L.).

Hexokinase (HXK) is a dual-function enzyme that both phosphorylates hexose to form hexose 6-phosphate and plays an important role in sugar sensing and signaling. To investigate the roles of hexokinases in rice growth and development, we analyzed rice sequence databases and isolated ten rice hexokinase cDNAs, OsHXK1 (Oryza sativa Hexokinase 1) through OsHXK10. With the exception of the single-exon gene OsHXK1, the OsHXKs all have a highly conserved genomic structure consisting of nine exons and eight introns. Gene expression profiling revealed that OsHXK2 through OsHXK9 are expressed ubiquitously in various organs, whereas OsHXK10 expression is pollen-specific. Sugars induced the expression of three OsHXKs, OsHXK2, OsHXK5, and OsHXK6, in excised leaves, while suppressing OsHXK7 expression in excised leaves and immature seeds. The hexokinase activity of the OsHXKs was confirmed by functional complementation of the hexokinase-deficient yeast strain YSH7.4-3C (hxk1, hxk2, glk1). OsHXK4 was able to complement this mutant only after the chloroplast-transit peptide was removed. The subcellular localization of OsHXK4 and OsHXK7, observed with green fluorescent protein (GFP) fusion constructs, indicated that OsHXK4 is a plastid-stroma-targeted hexokinase while OsHXK7 localizes to the cytosol.

Chromosome Mapping↗
PubMed2006

Co-cladogenesis spanning three phyla: leafhoppers (Insecta: Hemiptera: Cicadellidae) and their dual bacterial symbionts.

Endosymbioses are a major form of biological complexity affecting the ecological and evolutionary diversification of many eukaryotic groups. These associations are exemplified by nutritional symbioses of insects for which phylogenetic studies have demonstrated numerous cases of long-term codiversification between a bacterial and a host lineage. Some insects, including most leafhoppers (Insecta: Hemiptera: Cicadellidae), have more than one bacterial symbiont within specialized host cells, raising questions regarding the patterns of codiversification of these multiple partners and the evolutionary persistence of complex symbiotic systems. Previous studies reported the presence of two dominant symbiont types in a member of the leafhopper subfamily Cicadellinae (sharpshooters). In this study, 16S rRNA sequences were obtained and used to examine the occurrence and evolutionary relationships of the two dominant symbiont types across 29 leafhopper species. Candidatus Sulcia muelleri (Bacteroidetes) was detected in all leafhopper species examined, a finding that is consistent with a previous report of its ancient association with the Auchenorrhyncha (a grouping that includes leafhoppers, treehoppers, cicadas, planthoppers, and spittlebugs). Baumannia cicadellinicola (Proteobacteria), previously known from only five sharpshooter species, was found only in the sharpshooter tribes Cicadellini and Proconiini, as well as in the subfamily Phereurhininae. Mitochondrial and nuclear gene sequences were obtained and used to reconstruct host phylogenies. Analyses of host and symbiont data sets support a congruent evolutionary history between sharpshooters, Sulcia and Baumannia and thus provide the first strong evidence for long-term co-inheritance of multiple symbionts during the diversification of a eukaryotic host. Sulcia shows a fivefold lower rate of 16S rDNA sequence divergence than does Baumannia for the same host pairs. The term 'coprimary' symbiont is proposed for such cases.

Animals↗
PubMed2004

Minimal metabolic engineering of Saccharomyces cerevisiae for efficient anaerobic xylose fermentation: a proof of principle.

When xylose metabolism in yeasts proceeds exclusively via NADPH-specific xylose reductase and NAD-specific xylitol dehydrogenase, anaerobic conversion of the pentose to ethanol is intrinsically impossible. When xylose reductase has a dual specificity for both NADPH and NADH, anaerobic alcoholic fermentation is feasible but requires the formation of large amounts of polyols (e.g., xylitol) to maintain a closed redox balance. As a result, the ethanol yield on xylose will be sub-optimal. This paper demonstrates that anaerobic conversion of xylose to ethanol, without substantial by-product formation, is possible in Saccharomyces cerevisiae when a heterologous xylose isomerase (EC 5.3.1.5) is functionally expressed. Transformants expressing the XylA gene from the anaerobic fungus Piromyces sp. E2 (ATCC 76762) grew in synthetic medium in shake-flask cultures on xylose with a specific growth rate of 0.005 h(-1). After prolonged cultivation on xylose, a mutant strain was obtained that grew aerobically and anaerobically on xylose, at specific growth rates of 0.18 and 0.03 h(-1), respectively. The anaerobic ethanol yield was 0.42 g ethanol x g xylose(-1) and also by-product formation was comparable to that of glucose-grown anaerobic cultures. These results illustrate that only minimal genetic engineering is required to recruit a functional xylose metabolic pathway in Saccharomyces cerevisiae. Activities and/or regulatory properties of native S. cerevisiae gene products can subsequently be optimised via evolutionary engineering. These results provide a gateway towards commercially viable ethanol production from xylose with S. cerevisiae.

Aldose-Ketose Isomerases↗
PubMed1996

Detection of human papillomavirus in cervical biopsies of summer camp ROTC cadets with abnormal papanicolaou smears.

STUDY OBJECTIVE: Human papillomavirus (HPV) infections may be the most common sexually transmitted disease (STD) among adolescents and young adults. A strong association exists for certain "high-risk" HPV-type cervical infections and subsequent evolution of cervical cancer and its precursor lesions. The objective of this study was to detect HPV in cervical biopsies of reserve officer training corps (ROTC) cadets attending a regional summer camp who had abnormal screening Papanicolaou (Pap) smears and to better define the spectrum of HPV oncogenic risk types for this population. It was hypothesized that HPV would be detected in the majority of cervical biopsies in keeping with the evolving concept of cervical cancer and its precursors as an STD and the central role of HPV in its development. DESIGN: On arrival for summer military camp training, college women cadets underwent physical examinations that included pelvic examinations for Pap smears. Study participants completed confidential questionnaires after informed consent was obtained. Subjects, who had abnormal Pap smears as defined by reports of atypical squamous cells of undetermined significance (ASCUS) or low- or high-grade squamous intra-epithelial lesions (LGSIL or HGSIL), underwent colposcopic evaluations with cervical biopsies. Subsequently, biopsies were processed for detection of HPV-specific DNA by gel electrophoresis, chemiluminescent oligonucleotide probing, and DNA-RNA hybridization methods after polymerase chain reaction (PCR) amplification. PARTICIPANTS: All female summer camp enrollees presented to the Madigan Army Medical Center Gynecology Clinic for complete physicals before the onset of the training program and were solicited for study inclusion. MAIN OUTCOME MEASURES: All colposcopic biopsy specimens were evaluated for the presence of HPV DNA and subtyped if positive. RESULTS: Representing 42 states, 95% (332) of eligible subjects participated. Mean age was 21.9 years. Racial composition included 70% white, 16% black, 4% Hispanic, 4% Asian, and 6% "other." Eighty-five percent had a history of hetero-sexual activity, with 17.7 years as the mean age at onset. Of the subjects, 12.6% reported a previous diagnosis of a sexually transmitted disease, and 7.8% (26 of 332) had abnormal Pap smears. Of these, colposcopic biopsy results were available for 25 of the 26 abnormal Pap smears. Ninety-six percent (24 of 25) of the colpobiopsies had detectable HPV. Eighty-eight percent (22 of 25) of the subjects with abnormal Pap smears had concurrent abnormal biopsy results. All of these had detectable HPV, confirmed by three different methods, and 29% had dual HPV infection. Sixty percent had "intermediate" or "high-risk" types identified by specific genotyping, 8% had "low-risk" types, and 28% had nontypable HPV. CONCLUSIONS: The data confirm that abnormal Pap smears in this young adult college population are almost always associated with HPV infection, a significant proportion of it being other than low-risk types. The prognostic significance of type-specific cervical HPV infection still needs to be better defined in relation to potential cofactors and host immune response. However, clinicians who provide primary gynecologic care to adolescents and young adults should be aware of the high correlation between abnormal Pap smears and HPV cervical infection and should follow up the patient with the potential risk in mind.

Adolescent↗
PubMed2003

SGK1 regulation of epithelial sodium transport.

Epithelial ion transport is regulated in vertebrates by a variety of hormonal and non-hormonal factors, including mineralocorticoids, insulin, and osmotic shock. SGK1 has been established as an important convergence point for multiple regulators of Na+transport. Unlike most serine-threonine kinases, SGK1 is under dual control: protein levels are controlled through effects on its gene transcription, while its activity is dependent on phosphatidylinositol-3-kinase (PI3K) activity. Aldosterone is the most notable regulator of SGK1 protein level in ion transporting epithelia, while insulin and other activators of the of PI3K are key regulators of its activity. Activated SGK1 regulates a variety of ion transporters, the best characterized of which is the epithelial sodium channel (ENaC). The apical targeting of ENaC is controlled by the ubiquitin ligase, Nedd4-2, and SGK1 acts, at least in part, through phosphorylation-dependent inhibition of Nedd4-2. This effect of SGK1 requires physical associations of Nedd4-2 with both SGK1 and ENaC. Moreover, direct physical association between SGK1 and ENaC may also be implicated in the formation of a tertiary complex. Osmotic shock is likely the most important non-hormonal regulator of SGK1 expression, and surprisingly, SGK1 expression can be induced by hypotonic or hypertonic stress in a cell-type dependent fashion. The SGK family represents an ancient arm of the serine-threonine kinase family, present in all eukaryotes that have been examined, including yeast. SGK1 appears to have been implicated in membrane trafficking and possibly in the control of ion transport and cell volume in early single cell eukaryotes. In metazoan epithelia, it seems likely that SGK1 was adapted to the regulation of ion transport in response to hormonal and osmotic signals.

Aldosterone↗
PubMed1996

The mouse DNA binding protein Rc for the kappa B motif of transcription and for the V(D)J recombination signal sequences contains composite DNA-protein interaction domains and belongs to a new family of large transcriptional proteins.

Rc is a DNA binding protein with dual specificities for the V(D)J recombination signal sequences and for the B motif of the immunoglobulin kappa chain gene enhancer. The largest Rc transcript present in lymphoid cells/tissues is approximately 9 kb. Molecular cloning and sequence determination for 8822 bp of mouse Rc cDNA revealed an open reading frame of 2282 amino acids and long 5'- and 3'-untranslated regions. The derived amino acid sequence contains multiple DNA and protein interaction domains. Composite ZAS structures with tandem zinc fingers, an acidic motif, and a Ser/Thr-rich segment are located near the N-terminal and the C-terminal regions. The middle region of Rc contains a lone zinc finger, an acidic motif, a Ser-rich region, a nucleus localization signal, and GTPase motifs. Cloning and characterization of a mouse Rc gene show that the Rc cDNA corresponds to seven exons located in a genomic region spanning 70 kb. Exon 2 is exceptionally large, with 5487 bp. cDNA cloning and Northern blot analyses revealed multiple Rc transcripts, probably generated by alternative splicings. Sequence comparisons show that Rc belongs to a ZAS protein family that is involved in gene transcription and/or DNA recombination. The major histocompatibility complex class I gene enhancer binding proteins MBP1 and MBP2 are other representatives of this ZAS protein family.

Amino Acid Sequence↗
PubMed2001

Declining levels of rescued lymphoproliferative response to human cytomegalovirus (HCMV) in AIDS patients with or without HCMV disease following long-term HAART.

OBJECTIVE: To investigate the lymphoproliferative response (LPR) to human cytomegalovirus (HCMV) in two groups of AIDS patients undergoing long-term highly active antiretroviral therapy (HAART): group 1 ( n = 22) with nadir CD4(+) cell count <50/microl and no HCMV disease; group 2 ( n = 16) with <50/microl CD4(+) T-cell count and HCMV disease. All patients had previously undergone antiretroviral monotherapy or dual therapy before initiating HAART. STUDY DESIGN AND METHODS: The two groups of patients were tested prospectively for CD4(+) T cell count, HIV RNA load, HCMV viremia, and LPR to HCMV at baseline, and then after 3 and 4 years of HAART. A control group of 13 recently diagnosed treatment-naive AIDS patients with CD4(+) T-cell counts <100/microl was also investigated. RESULTS: No LPR to HCMV was found in any of the treatment-naive patients nor in any patient of the two groups examined at baseline, when HCMV viremia was 13.6% in the patient group without disease and 87.5% in the group with disease ( p <.0001). After 3 years of HAART, the frequency of patients who recovered an LPR to HCMV was not significantly different (81.8% in the group without HCMV disease, and 68.7% in the group with HCMV disease), whereas, compared with baseline, the HIV load decreased and the CD4(+) T-cell count increased significantly and to a comparable extent in the two groups of patients. In addition, the frequency of patients with HCMV viremia, although reduced, became comparable in both groups. After 4 years of HAART, the frequency of responders to HCMV without and with HCMV disease dropped to comparable levels (50.0 vs. 56.3%, respectively) in association with high median CD4(+) T-cell counts and low median HIV RNA plasma levels. In parallel, the frequency of patients with HCMV viremia did not change significantly. In addition, after between 3 and 4 years of HAART, although the frequency of stable responders and nonresponders remained unchanged (50%) in both groups, most of the remaining patients showed declining levels of responsiveness to HCMV. Although some patients from both groups were found to have CD4(+) T-cell counts >150/microl in the absence of LPR to HCMV, thus suggesting dissociation of specific and nonspecific immune reconstitution, a significant correlation was found between CD4(+) T-cell count and LPR to HCMV (r = 0.44; p <.001). From a clinical standpoint, anti-HCMV therapy could be safely discontinued in 8 patients with HCMV retinitis showing CD4(+) T-cell counts >150/microl, recovery of HCMV LPR, and no HCMV viremia. CONCLUSIONS: Declining levels of the previously recovered LPR to HCMV are often observed after long-term HAART. However, because the role of LPR in the evolution of HCMV infection and disease during HAART remains to be defined, the clinical impact of the declining LPR to HCMV must still be clarified in long-term prospective studies.

AIDS-Related Opportunistic Infections↗
PubMed2001

Surfactant-associated proteins: functions and structural variation.

Pulmonary surfactant is a barrier material of the lungs and has a dual role: firstly, as a true surfactant, lowering the surface tension; and secondly, participating in innate immune defence of the lung and possibly other mucosal surfaces. Surfactant is composed of approximately 90% lipids and 10% proteins. There are four surfactant-specific proteins, designated surfactant protein A (SP-A), SP-B, SP-C and SP-D. Although the sequences and post-translational modifications of SP-B and SP-C are quite conserved between mammalian species, variations exist. The hydrophilic surfactant proteins SP-A and SP-D are members of a family of collagenous carbohydrate binding proteins, known as collectins, consisting of oligomers of trimeric subunits. In view of the different roles of surfactant proteins, studies determining the structure-function relationships of surfactant proteins across the animal kingdom will be very interesting. Such studies may reveal structural elements of the proteins required for surface film dynamics as well as those required for innate immune defence. Since SP-A and SP-D are also present in extrapulmonary tissues, the hydrophobic surfactant proteins SP-B and SP-C may be the most appropriate indicators for the evolutionary origin of surfactant. SP-B is essential for air-breathing in mammals and is therefore largely conserved. Yet, because of its unique structure and its localization in the lung but not in extrapulmonary tissues, SP-C may be the most important indicator for the evolutionary origin of surfactant.

Amino Acid Sequence↗