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PubMed1993

Prevention of phospholipase-C induced aggregation of low density lipoprotein by amphipathic apolipoproteins.

Phospholipase C (PL-C) digestion of human low density lipoprotein (LDL) results in hydrolytic cleavage of the phosphocholine head group of phosphatidylcholine, thereby generating diacylglycerol. Loss of amphiphillic surface lipids and/or accumulation of diacylglycerol causes LDL samples to develop turbidity. Examination of PL-C treated LDL by electron microscopy revealed a progressive aggregation of LDL as a function of phosphatidylcholine hydrolysis: fused particles, clusters, and multiple stacked aggregates were observed. Lipid analysis of untreated and aggregated LDL confirmed that the phosphatidylcholine content of the latter had decreased with a corresponding increase in diacylglycerol. It is likely that phospholipolysis created hydrophobic gaps within the surface monolayer of LDL, thereby inducing LDL fusion and aggregation. When amphipathic alpha-helix-containing apolipoproteins, such as human apoA-I or Manduca sexta apolipophorin III (apoLp-III) were present, PL-C treated LDL did not aggregate. Compositional analysis of apolipoprotein-containing PL-C LDL showed that phospholipolysis was not affected by the presence of apolipoproteins. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of lipoproteins re-isolated following incubation with PL-C revealed an association of apoA-I or apoLp-III with PL-C digested LDL. Electron microscopy showed no major morphological differences between native LDL and apoprotein stabilized PL-C treated LDL and the average particle diameter of apoA-I stabilized PL-C LDL was 22.5 +/- 2.2 nm versus 22.8 +/- 1.6 nm for control LDL. Incubation of tritium-labeled apoLp-III with LDL and PL-C demonstrated that association of apoLp-III with PL-C LDL correlated with the extent of phospholipid hydrolysis, the apolipoproteins apparently being recruited to compensate for the increased hydrophobic surface created by conversion of phosphatidylcholine into diacylglycerol. The results suggest that transient association of amphipathic apolipoproteins with damaged or unstable LDL may provide a mechanism to obviate formation of atherogenic LDL aggregates in vivo.

Animals↗
PubMed1983

Transcription terminates in yeast distal to a control sequence.

We have investigated transcription termination on a segment of Drosophila DNA that complements a yeast adenine-8 mutation. Poly(A)+ RNA transcribed from this segment in yeast terminates at multiple sites clustered just beyond an AAUAAA sequence implicated in polyadenylation of higher eucaryotic messages. Deletion analysis indicates that, in yeast, this sequence is not required for polyadenylation. Rather, transcription termination is signalled by a region that is upstream of the AAUAAA sequence. At least part of the control region appears to be an 8-base pair (bp) sequence also found in the termination control region of the yeast CYC1 gene. Termination sites for the various deletions show a clear sequence preference. These sites occur in clusters at least 50 bp downstream of the control region, suggesting similarities between termination in yeast and p-dependent termination in bacteria.

Animals↗
PubMed1993

The transcript encoding the circumsporozoite antigen of Plasmodium berghei utilizes heterogeneous polyadenylation sites.

We have employed polymerase chain reaction-based techniques to examine the transcript encoding the circumsporozoite (CS) antigen, the immunodominant coat protein of the infectious stage of the murine parasite Plasmodium berghei. Earlier studies suggested that the 3' terminus of the CS message might be determined by transcription termination rather than by cleavage and polyadenylation, as in most eukaryotes. Here we report that a subset of CS messages are polyadenylated. Moreover, the poly(A) tails are added at multiple sites clustered within a short region 300 bp downstream from the stop codon. Whether 3' end heterogeneity is peculiar to the CS message or a common feature of plasmodial transcripts remains to be determined.

Animals↗
PubMed1992

Organization of non-vertebrate globin genes.

The organization of non-vertebrate globin genes exhibits substantially more variability than the three-exon, two-intron structure of the vertebrate globin genes. (1) The structures of genes of the single-domain globin chains of the annelid Lumbricus and the mollusc Anadara, and the globin gene coding for the two-domain chains of the clam Barbatia, are similar to the vertebrate plan. (2) Genes for single-domain chains exist in bacteria and protozoa. Although the globin gene is highly expressed in the bacterium Vitreoscilla, the putative globin gene hmp in E. coli, which codes for a chimeric protein whose N-terminal moiety of 139 residues contains 67 residues identical to the Vitreoscilla globin, may be either unexpressed or expressed at very low levels, despite the presence of normal regulatory sequences. The DNA sequence of the globin gene of the protozoan Paramecium, determined recently by Yamauchi and collaborators, appears to consist of two exons separated by a short intron. (3) Among the lower eukaryotes, the yeasts Saccharomyces and Candida have chimeric proteins consisting of N-terminal globin and C-terminal flavoprotein moieties of about the same size. The structure of the gene for the chimeric protein of Saccharomyces exhibits no introns. According to Riggs, the presence of chimeric proteins in E. coli and other prokaryotes, such as Alcaligenes and Rhizobium, as well as in yeasts, suggests a previously unrecognized evolutionary pathway for hemoglobin, namely that of a multipurpose heme-binding domain attached to a variety of unrelated proteins with diverse functions. (4) The published globin gene sequences of the insect larva Chironomus have an intron-less structure and are present as clusters of multiple copies; the expression of the globin genes is tissue and developmental stage-specific. Furthermore, the expression of many of these genes has not yet been demonstrated despite the presence of apparently normal regulatory sequences in the two flanking regions. Unexpectedly, Bergtrom and collaborators have recently shown that at least three Ctt globin II beta genes contain putative introns. (5) Pohajdak and collaborators have found a seven-exon and six-intron structure for the globin gene of the nematode Pseudoterranova which codes for a two-domain globin chain. Although the second and fourth introns of the N-terminal domain correspond to the two introns found in vertebrate globin genes, the position of the third intron is close to that of the central intron in plant hemoglobins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1996

Characterization of the rat hippocalcin gene: the 5' flanking region directs expression to the hippocampus.

Hippocalcin is an EF-hand [Persechini A. et al. (1989) Trends Neurosci. 12, 462-467] Ca2+ binding protein encoded by a neuron-specific gene. A detailed atlas of hippocalcin messenger RNA expression in the adult rat brain was complied using in situ hybridization. Highest levels of messenger RNA are found in the hippocampus, where messenger RNA is localized in proximal dendrites of CA pyramidal cells. Expression is also seen in other brain regions, including the neocortex, caudate-putamen, taenia tecti, claustrum, olfactory tubercle, anterior olfactory nucleus, and granule cell and glomerular layers of the olfactory bulb. The rat hippocalcin gene spans approximately 9 kb and consists of three exons, separated by introns of 6.7 and 0.25 kb. Sequence analysis of the putative proximal promoter region identified two clusters of multiple E-box sites which may regulate the cell-specific expression. Two lacZ fusion constructs carrying 0.9 and 3.4 kb of rat hippocalcin gene upstream region were used to create transgenic mice. With the 3.4 kb construct, transgene expression varied between founder mice, but was always found in the dentate gyrus and CA1-CA4 regions of the hippocampus, thus partly mimicking the expression of the endogenous gene. For the 0.9 kb construct, the levels of lacZ expression were weaker and more variable. Neither construct showed expression in any peripheral tissues examined. To establish an in vitro model of transcriptional regulation, the 3.4 and 0.9 kb 5' upstream regions were fused to a promoterless reporter gene encoding chloramphenicol acetyltransferase and transiently transfected into the hippocalcin-positive NG-108 cells. The 3.4 kb construct was strongly expressed, whilst the 0.9 kb construct was not expressed. In this paper, we describe the detailed expression pattern of the rat hippocalcin gene, the gene structure and its neuron-specific promoter.

Animals↗
PubMed1994

Structure and expression of an inducible HSP70-encoding gene from Mus musculus.

We have determined the nucleotide sequence of a stress-inducible mouse Hsp70-encoding gene named hsp70A1. The gene encodes a 641-amino-acid protein whose deduced sequence is similar to those of other members of the HSP70 family. The 5' end (tsp) of a heat-inducible mRNA is 225 bp upstream from the start codon, and several consensus recognition sequences for transcription factors lie upstream from this tsp. There are 17 putative binding sites for heat-shock transcription factor (HSF), including three clusters of multiple binding sites. We show that this upstream region is sufficient to direct heat-inducible expression of a hsp70A1::cat hybrid gene in mouse and human cells.

Amino Acid Sequence↗
PubMed1989

Multiple tandem 18-kb sequences clustered in the region of the acute promyelocytic leukemia breakpoint on chromosome 17.

This paper describes the cloning of an 18-kb sequence present in approximately 30 copies on chromosome 17. Most of these are clustered in the region of the breakpoint associated with acute promyelocytic leukemia (APL). These copies map both above and below the breakpoint, and pulsed field gel analysis indicates that the majority of these sequences lie within a region of approximately 2 megabases. The organization of these sequences appears to be that of large imperfect palindromes.

Animals↗
PubMed1992

Acute thrombosis of prosthetic valves: a multivariate analysis of the risk factors for a lifethreatening event.

In 3231 prosthetic valves implanted between January 1975 and November 1990, we observed 61 cases of prosthetic obstruction of biological origin with clinical and laboratory findings of severe functional impairment which required surgery as emergency treatment. The hospital mortality was 19.67% (12/61). The obstruction was due to a primary thrombosis in all 5 bioprostheses which were not anticoagulated and in 11/56 (19.64%) mechanical prostheses of which 3 were not anticoagulated and 4 were not properly anticoagulated. The obstruction was due to fibrous tissue overgrowth in the other 45 mechanical prostheses (80.35%) with secondary thrombosis in 34 cases (60.71%) and no thrombosis in 11 (19.64%); 71.11% of these prostheses were adequately anticoagulated. Of the 61 obstructed prostheses, 53 were mitral and 8 were aortic. No tricuspid obstruction was observed. A statistical assessment by multiple correspondence, cluster and chi square analysis was performed in two groups of patients with different models of mechanical mitral prostheses. The 5-year actuarial incidence of obstruction was 6.08%. Significant risk factors were: tilting disc prostheses, prostheses without pyrocarbon coating, large prostheses, tilting disc prostheses with a small orifice posteriorly oriented, atrial fibrillation, enlarged left atrium, time from implant greater than 4 years, age between 40 and 50 years. In our opinion, prosthetic obstruction may be referred to a primary thrombosis only in cases where it may be prevented by adequate anticoagulation. In most cases, the obstruction is produced by periprosthetic fibroblastic proliferation which may develop in spite of adequate anticoagulation in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2005

Subcutaneous sarcoidosis: is it a specific subset of cutaneous sarcoidosis frequently associated with systemic disease?

BACKGROUND: Skin is involved in 25% of cases of sarcoidosis. The lesions are specific and nonspecific depending on the presence or absence of granulomas, respectively. Specific lesions are not thought to have prognostic significance and are not associated with systemic disease. OBJECTIVE: We sought to evaluate for the presence or absence of systemic disease in patients with subcutaneous sarcoidosis. METHODS: With diagnostic criteria of subcutaneous sarcoidosis, 33 cases were identified in the literature and 21 cases in our institutional database. A retrospective clinical and pathologic review of these cases was conducted. RESULTS: Subcutaneous sarcoidosis is characterized by a peak incidence during the fourth decade; female predisposition; asymptomatic to slightly tender lesions typically involving the upper extremities; cutaneous lesional clustering and multiplicity; autoimmune disease associations at time of diagnosis in a subset of cases; systemic disease associations at diagnosis in most patients, typically consisting of bilateral hilar adenopathy; and a favorable response to oral corticosteroid therapy. LIMITATIONS: Retrospective analysis with inadequate documentation of therapeutic regimens and their responses in some cases is a limitation of this study. CONCLUSIONS: The confirmatory diagnosis of subcutaneous sarcoidosis depends on identifying pannicular noninfectious sarcoidal or epithelioid granulomas with minimal lymphocytic inflammation. Subcutaneous sarcoidosis is the only specific subset of cutaneous sarcoidosis frequently associated with systemic disease.

Humans↗
PubMed2004

Aberrant nestin expression during ethylnitrosourea-(ENU)-induced neurocarcinogenesis.

Nestin is a unique intermediate filament protein. While it is robustly expressed in developing brain, postnatal expression is limited to the brain's subventricular zone (SVZ) and endothelial cells. Reexpression occurs, however, under several pathological conditions, including injury and neoplasia. We hypothesized that nestin would be a sensitive marker of early neoplasia after transplacental exposure of rats to ethylnitrosourea (ENU). Rats of various ages were administered bromodeoxyuridine (BudR) before sacrifice, and brain sections were examined for proliferative cells and several immunohistochemical markers, including nestin. Additional rats were examined after a stab wound injury to assess the expression of two of these markers, GFAP and nestin, in reactive astrocytes. All ENU-induced brain tumors (n = 9) were classified as gliomas (astrocytomas or oligoastrocytomas) based on their histology and immunophenotype. Nestin expression was noted in all tumors examined and was present in tumor cells as well as endothelial cells. During tumor development, we consistently noted nestin-expressing cells bearing multiple processes distributed throughout brain parenchyma. Both single cells and multiple cell clusters were observed as early as postnatal day 30 in all ENU-exposed brains examined (n = 11). Such distinctive nestin-expressing cells were not seen in nestin-stained control brains or ENU-exposed brains stained for GFAP or vimentin, nor was such a cell seen in a stab wound model used to assess reactive astrocytosis. While the number of these clusters was highly variable among rats, their size increased between 30 and 90 days. The data suggest that these nestin-expressing cells represent an early stage of the neoplastic process. It remains to be determined whether these cells become apparent at 30 days of age due to "dedifferentiation" of a local resident astrocyte or astrocyte precursor cell or migration of a relatively undifferentiated precursor/stem cell from the SVZ.

Animals↗
PubMed2003

Influence of solvation interactions on the zeta potential of titania powders.

The influence of solvation interactions on the surface charge of titania powders was studied by means of linear solvation energy relationships (LSER). The zeta potential (ZP) of titania powders and the effect of water content were determined in a series of alcohols, including methanol, ethanol, 1-propanol, isopropanol, and 1-butanol. The ZPs against the solvents' 13 LSER descriptors were analyzed by principal component analysis (PCA), cluster analysis, multiple linear regression (MLR), and stepwise multiple regression (SMR). Very good correlation between ZP and LSER parameter was obtained. One LSER parameter, relative dielectric constant, epsilon, was used to establish the LSER equation. The ZP of titania powders in pure alcohols can be reasonably calculated by an empirical formula: ZP=13.43-213.63.1/epsilon. The results show that epsilon is the most important factor governing the ZP of titania powders. The results also suggest that the effect of solvation interactions on ZP is a result of the electrostatic interactions between powders and solvents.

Alcohols↗
PubMed2000

Mutation spectra induced by replication of two vicinal oxidative DNA lesions in mammalian cells.

Ionizing radiations often induce multiple and clustered DNA lesions at the site of DNA interaction. As a model, we have studied the toxicity and the mutagenicity of two adjacent oxidative bases as clustered DNA lesions in mammalian cells using shuttle vectors. The chosen oxidative lesions were 8-oxo-7,8-dihydroguanine, the formylamine residue resulting from the oxidation of a pyrimidine base and the tandem lesion 8-oxo-7,8-dihydroguanine/formylamine where both modifications are located at a vicinal position. A single-stranded DNA shuttle vector carrying a unique DNA lesion was constructed, transfected into simian COS7 cells and mutations induced after replication in mammalian cells were screened in bacteria. 8-oxo-7,8-dihydroguanine, as expected, does not affect greatly survival (70% bypass) whereas formylamine and the tandem lesions are blocking alterations, DNA polymerase bypass being of 45% and 17%, respectively. Base insertion opposite the lesion was studied. Under our experimental conditions, replication of 8-oxo-7, 8-dihydroguanine finally gives rise to guanine:cytosine pairing, rendering this lesion only slightly mutagenic. This is not the case for the formylamine that codes preferentially for adenine (71%). In addition, one-base deletions were observed targeted to the site to the lesion. Cytosine and thymine were inserted opposite the lesion with similar but low frequencies. Thus, coding properties of the formylamine render this residue very mutagenic when coming from the oxidative alteration of a cytosine. The coding properties of the tandem damage are a combination of the contribution of the two isolated lesions with a very high percentage of adenine insertion (94%) opposite the formylamine residue of the tandem lesion. The toxicity as well as the mutation spectrum of the tandem lesion allow us to speculate about the molecular mechanism with which the DNA polymerase replicates these two lesions.

Animals↗
PubMed2005

[Unusual presentation of infantile myofibromatosis with an ulcered plaque].

INTRODUCTION: Infantile myofibromatosis is a rare fibrovascular-like, isolated or multicentric tumor, occasionally of the bone or an organ and appearing before the age of 2. We report a case of infantile myofibromatosis in a child in an atypical form with a single, ulcerated plaque and having developed after the onset of clusters of papular nodules. OBSERVATION: An infant was seen in consultation because of asymptomatic papules that had developed on the back. The histological examination of a partial biopsy revealed a histiocytofibromatus aspect and led to the diagnosis of clusters of multiple histiocytofibromatous. One year later, the papular nodules had converged, forming a large plaque with ulcerated center. The progressive extension and the absence of healing prompted surgical exeresis and the final diagnosis of myofibromatosis. DISCUSSION: Diagnosis of infantile myofibromatosis is difficult histologically and clinically and relies on a clear anatomoclinical confrontation. The clinical aspects are varied. To our knowledge, myofibromatosis with a single ulcerated plaque has never been reported in the literature before.

Humans↗
PubMed1999

A view from the genome: spatial control of transcription in sea urchin development.

The process of embryogenesis depends on differential regulation of genes in the spatial components defined by the embryonic cells (blastomeres). Developmental regulation is mediated by complex, hardwired genomic control systems consisting of clusters of multiple target sites at which specific interactions with regionally presented transcription factors occur. In the age of genomics and gene-transfer technology, the sea urchin embryo provides unique opportunities for experimental analysis of these processes. Research on gene regulation in sea urchin embryos in the past year has seen remarkable progress in two large areas: in understanding functional cis-regulatory architecture; and in understanding the mechanism by which the axial coordinates of the egg are transduced into a molecular system for differential gene activation.

Animals↗
PubMed1999

The lived experience of having an ileoanal reservoir: a phenomenologic study.

OBJECTIVE: Ileoanal reservoir (IAR) surgery or ileal pouch anal anastomosis is a relatively new surgical technique for people with ulcerative colitis or familial adenomatous polyposis. Little attention has been given to the experiences of people undergoing the procedure. The purpose of this qualitative study was to understand the lived experience of persons who have had construction of an IAR. DESIGN: The study was grounded in the phenomenologic approach of Van Manen to capture the lived experience of having an IAR as perceived by those persons in their everyday world. SETTING AND SUBJECTS: A purposive sample of 10 individuals with direct and personal knowledge of the experience were interviewed in detail. Subjects were recruited by contact with an IAR support group and a local WOCN group. All interviews were conducted in a private setting in a health care facility, school, or the participant's home. METHODS: Data collection involved face-to-face interviews lasting from 1 to 2 hours. Interviews were audiotaped and transcribed. MAIN OUTCOME MEASURES: Demographic data from the interviews were tabulated. Analyses of transcripts revealed 10 essential thematic categories with multiple theme clusters of the IAR experience related to lived body, time, space, and relationships. Analyses were completed by the researcher and a faculty mentor. RESULTS: The particular thematic categories that evolved from the data were (1) restricted life world, (2) living with uncertainty and fear, (3) seeking control, (4) vicious cycles: crisis and normalcy, (5) seeking and giving support, (6) alienation from the body, (7) living with bodily alterations, (8) the gift of time, (9) role and relationship changes, and (10) the end of the tunnel but relative results. All 10 theme categories were correlated with a literature review and other sources. CONCLUSION: The study provides a portrait of courage and survival for individuals experiencing major surgical interventions and bodily invasion associated with IAR after years of living with UC. Implications for nurses and health care personnel and questions for future research are presented.

Activities of Daily Living↗
PubMed1996

Recurrent aphthous stomatitis. An update.

Recurrent aphthous ulceration or recurrent aphthous stomatitis is the most common oral mucosal disease known to human beings. Despite much clinical and research attention, the causes remain poorly understood, the ulcers are not preventable, and treatment is symptomatic. The most common presentation is minor recurrent aphthous stomatitis: recurrent, round, clearly defined, small, painful ulcers that heal in 10 to 14 days without scarring. Major recurrent aphthous stomatitis lesions are larger (greater than 5 mm), can last for 6 weeks or longer, and frequently scar. The third variety of recurrent aphthous stomatitis is herpetiform ulcers, which present as multiple small clusters of pinpoint lesions that can coalesce to form large irregular ulcers and last 7 to 10 days. Diagnosis of all varieties is usually made after clinical examination. Many local and systemic factors have been associated with these conditions, and there is evidence that there may be a genetic and immunopathogenic basis for recurrent aphthous ulceration. Management of this condition depends on the clinical presentation and symptoms and includes analgesic, antimicrobial, and immunomodulatory drugs. As dental clinicians and researchers become better trained in oral medicine and stomatology, it is anticipated that the pathophysiology, prevention, and treatment of recurrent aphthous ulceration will improve in the future.

Adjuvants, Immunologic↗
PubMed2007

Excluding infants under 6 months of age from surveys: impact on prevalence of pre-school undernutrition.

OBJECTIVE: Infants aged 0-5 months are not systematically included in assessments of child nutritional status and are generally excluded from surveys conducted in emergencies. We estimated the impact of excluding 0-5-month-old infants on the prevalence of stunting, wasting and underweight among children under 5 years (U5) and under 3 years (U3) of age. DESIGN: Comparison of the prevalence of stunting, wasting and underweight in U5 and U3 with or without inclusion of the age group 0-5 months. SETTING: Demographic and Health Surveys and Multiple Indicator Cluster Surveys from 76 developing countries and countries in transition. SUBJECTS: Children under 3 or under 5 years of age included in the surveys. Results Excluding 0-5-month-old infants resulted in an overestimation of the prevalence of stunting, wasting and underweight in U5 of 3.0, 0.3 and 2.6 percentage points, respectively, and of 4.8, 1.0 and 5.2 percentage points, respectively, in U3. The overestimation for wasting was negligible. The regions showing the highest overestimations for stunting and underweight were Asia and sub-Saharan Africa. Overall, countries with high prevalences of stunting and underweight showed especially large overestimations. The prevalence of underweight in infants aged 0-5 months was correlated with the prevalence of low maternal body mass index. CONCLUSION: All surveys, even in situations of nutrition emergency, should include 0-5-month-old infants. Strictly comparable age ranges are essential in nutrition surveys for monitoring trends and evaluating programme impact. Greater awareness of prenatal and early child undernutrition is needed among policy-makers.

Age Factors↗
PubMed1991

Alteration of the iron-sulfur cluster composition of Escherichia coli dimethyl sulfoxide reductase by site-directed mutagenesis.

We have used site-directed mutagenesis to alter the [Fe-S] cluster composition of Escherichia coli dimethyl sulfoxide (DMSO) reductase (DmsABC). The electron-transfer subunit (DmsB) of this enzyme contains 16 Cys residues arranged in 4 groups (I-IV) which provide ligands to 4 [4Fe-4S] clusters [Cammack, R., & Weiner, J. H. (1990) Biochemistry 29, 8410-8416]. Strong homologies exist between these Cys groups and the four Cys groups of the electron-transfer subunit (NarH) of E. coli nitrate reductase (NarGHJI), which contains a [3Fe-4S] cluster in addition to multiple [4Fe-4S] clusters. The Cys group primarily involved in providing ligands to the [3Fe-4S] cluster of NarH has a Trp residue at a position equivalent to Cys102 of DmsB. We have mutated Cys102 to Trp, Ser, Tyr, and Phe and have investigated the altered enzymes in terms of their enzymatic activities and EPR properties. The mutant enzymes do not support electron transfer from menaquinol to DMSO, although they retain high rates of electron transport from reduced benzyl viologen to DMSO. The mutations cause major changes in the EPR properties of the enzyme in the fully reduced and oxidized states. In the oxidized state, new species are observed in all the mutants; these have spectral features comprising a peak at g = 2.03 (gz) and a peak-trough at g = 2.00 (gxy). The temperature dependencies, microwave power dependencies, and spin quantitations of these species are consistent with the Trp102, Ser102, Phe102, and Tyr102 mutations causing conversion of one of the [4Fe-4S] clusters present in the wild-type enzyme into [3Fe-4S] clusters in the mutant enzymes.

Amino Acid Sequence↗