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PubMedDate not supplied

Chronic fatigue syndrome: issues in the diagnosis and estimation of incidence.

This article critiques the current working definition of chronic fatigue syndrome. The concerns raised about the current working definition are the following: prolonged or excessive exertion is not addressed explicitly; duration and quality of bed rest are not specified; a socioeconomic ascertainment bias is present; data from history and physical findings are not clearly separated and are relegated to minor criteria; and the rigor of neurologic and psychiatric evaluations is not specified. We propose a flow chart that addresses the possible modes of evolution of chronic fatigue syndrome for patients; this chart may yield more homogeneous subgroups of individuals with this syndrome or enable some patients to avert the syndrome.

Fatigue Syndrome, Chronic↗
PubMed1996

Rubisco in marine symbiotic dinoflagellates: form II enzymes in eukaryotic oxygenic phototrophs encoded by a nuclear multigene family.

Genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were cloned from dinoflagellate symbionts (Symbiodinium spp) of the giant clam Tridacna gigas and characterized. Strikingly, Symbiodinium Rubisco is completely different from other eukaryotic (form I) Rubiscos: it is a form II enzyme that is approximately 65% identical to Rubisco from Rhodospirillum rubrum (Rubisco forms I and II are approximately 25 to 30% identical); it is nuclear encoded by a multigene family; and the predominantly expressed Rubisco is encoded as a precursor polyprotein. One clone appears to contain a predominantly expressed Rubisco locus (rbcA), as determined by RNA gel blot analysis of Symbiodinium RNA and sequencing of purified Rubisco protein. Another contains an enigmatic locus (rbcG) that exhibits an unprecedented pattern of amino acid replacement but does not appear to be a pseudogene. The expression of rbcG has not been analyzed; it was detected only in the minor of two taxa of Symbiodinium that occur together in T. gigas. This study confirms and describes a previously unrecognized branch of Rubisco's evolution: a eukaryotic form II enzyme that participates in oxygenic photosynthesis and is encoded by a diverse, nuclear multigene family.

Amino Acid Sequence↗
PubMed1990

Cometary delivery of organic molecules to the early Earth.

It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10(9) to 3.8 x 10(9) years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, we find that 4.5 x 10(9) years ago Earth was accreting intact cometary organics at a rate of at least approximately 10(6) to 10(7) kilograms per year, a flux that thereafter declined with a half-life of approximately 10(8) years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, approximately 3 x 10(12) kilograms and approximately 6 x 10(14) kilograms, respectively.

Amino Acids↗
PubMed2004

High-resolution genotyping of Campylobacter upsaliensis strains originating from three continents.

Ninety-six Campylobacter upsaliensis strains that originated from Australia, Canada, and Europe (Germany) and that were isolated from humans, dogs, and cats were serotyped for their heat-stable surface antigens. All of them were genotyped by enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) profiling, and 83 strains were genotyped by macrorestriction analysis with the endonuclease XhoI. Eighty-four percent of the strains belonged to five different serotypes (serotypes OI, OII, OIII, OIV, and OVI), with the proportions of strains in each serotype being comparable among the groups of strains from all three continents. Two serotypes, OIII and OIV, were prevalent at rates of 35 to 40%. Serotypes OI, OII, and OVI were detected at rates of 1.5 to 15%. Between 10 and 17.7% of the strains did not react with the available antisera. Analysis of the ERIC-PCR profiles revealed two distinct genotypic clusters, which represented the German and the non-European strains, respectively. XhoI macrorestriction yielded two genotypic clusters; one of them contained 80.2% of the German strains and 34.6% of the non-European strains, and the second cluster consisted of 65.4% of the non-European strains and 19.8% of the German strains. Fourteen strains from all three continents were analyzed for their 16S rRNA gene sequences. Only two minor variations were detected in four of the strains. In conclusion, C. upsaliensis has undergone diverging processes of genome arrangement on different continents during evolution without segregating into different subspecies.

Animals↗
PubMed1993

The Australian Incident Monitoring Study. The electrocardiograph: applications and limitations--an analysis of 2000 incident reports.

The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed with respect to the role of the electrocardiograph (ECG). Of these, 138 (7%) were first detected by the ECG. Of the 1256 incidents which occurred in association with general anaesthesia (GA incidents) 48% were "human detected" and 52% "monitor detected", the ECG was ranked third and detected 121 (19%) of these monitor detected GA incidents. However over 98% of incidents first detected by the ECG were heart rate changes; they would also have been detected by a pulse meter or pulse oximeter which would have supplied additional information about the adequacy of peripheral perfusion. The ECG is a "first-line" monitor in situations with the potential for myocardial ischaemia, complex dysrhythmias or altered myocardial conduction and should be used in all critically ill patients as well as those at significant risk of these problems. The ECG frequently detects incidents involving minor physiological trespass, such as simple heart rate and rhythm changes associated with anaesthetic agents. These incidents are generally detected relatively early in their evolution. AIMS data has confirmed, however, that the ECG has such poor sensitivity for serious physiological changes such as hypoxia, hypercarbia and hypotension that it cannot even be regarded as a useful "back-up" monitor for these problems. Indeed a "normal" ECG in a dangerous situation may lead to a degree of complacency.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents↗
PubMedDate not supplied

Heterogeneity of HVR-1 quasispecies is predictive of early but not sustained virological response in genotype 1b-infected patients undergoing combined treatment with PEG- or STD-IFN plus RBV.

ISDR mutation pattern and HVR-1 quasispecies were analyzed in HCV genotype 1b-infected patients treated with either PEG- or STD-IFN plus ribavirin, in order to find virological correlates of therapy outcome. ISDR region analysis, performed at baseline (T0) and at 4 weeks of therapy (T1), indicated that ISDR mutation pattern was not predictive of response to treatment. Moreover, no selection of putative resistant strains in the first month of therapy was observed. Viral load was not correlated with any parameter of HVR-1 heterogeneity. Among the HVR-1 heterogeneity parameters considered, complexity was inversely correlated to viral load decline at T1. In univariate analysis, complexity, proportion of non synonymous substitutions (NS) and NS/S ratio were lower in patients showing virological response at 6 months of treatment. Complexity was the only parameter independently associated with both decline of viral load at T1 and virological response after 6 months, even after adjustment for confounding variables. At the end of treatment or later, these correlations were lost. Evolution pattern of the HVR-1 quasispecies indicated a strong selective pressure in sustained responders, with complete substitution of pre-existing quasispecies, while minor changes occured in non responders. In relapsers both patterns were present at a similar rate. In conclusion, this study shows that HVR-1 heterogeneity may be involved in the early response to combined IFN-RBV therapy. The loss of correlation between viral heterogeneity and therapy outcome at 6 months of therapy, or later, suggests that other factors may play a role in maintaining sustained response to treatment.

Antiviral Agents↗
PubMed1985

[Immature cutaneous hemangiomas. Epidemiologic study of 351 cases].

The purpose of this study was to determine the course of cutaneous immature angiomas in a population of 362 children examined in a pediatric dermatology unit from 1975 to 1982. 461 angiomas were observed in these patients: 110 were of the naevus flammaeus type (port wine stain) including 23 forehead salmon patches. 351 were immature angiomas (IA)--strawberry angiomas. 3.5 p. 100 of children were afflicted of two types of hemangiomas. Results concerning the 282 patients with 351 IA are detailed as followed: average follow-up: 2 years; sex-ratio M/S 1.9, most of them Caucasians. Prematurity (data obtained prospectively during 1982): 19 p. 100; clinical features: dermal: 253, subcutaneous: 35, mixed pattern 63; 2 IA or more were detected in 12 p. 100 of the patients; site: head and neck; 49 p. 100, trunk: 21 p. 100, upper limbs: 14.5 lower limbs: 12 p. 100, genitals 3.5 p. 100; maximal size during follow-up: less than 1 cm: 36 p. 100, between 1 and 3 cm: 43 p. 100, more than 3 cm; 21 p. 100; time of onset: 51 p. 100 were noted at birth, 35 p. 100 during the first month, 13 p. 100 after the first month. Course of untreated IA is shown in figure 1. At the end of follow-up, spontaneous evolution in 52 patients was judged; very good in 44 p. 100, good in 41 p. 100, poor or bad in 15 p. 100. Minor complications (ulceration, infection, bleeding) were observed in 12.8 p. 100. Functional impairment requiring therapy was present in 2/4 plantar IA, 3/30 eyelid IA, 3/3 IA with laryngeal involvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Comparative study on the evolution of chloroplast ribosomal 5S RNA of a living fossil plant, Cycas revoluta Thumb.

The complete nucleotide sequence of Cycas revoluta Thunb chloroplast 5 S rRNA was determined. It consists of 122 nucleotides. This is the only known 5 S rRNA sequence in Gymnospermae. It is highly homologous with chloroplast 5 S rRNA of higher plants (92-97%), but less homologous (about 54%) with those of lower plants. There is however 67% homology between Cycas and a procaryote a. nidulans. The chloroplast 5 S rRNAs of Angiospermae are nearly identical with each other (95-97%). S. oligorhize and L. minor have 100% homology among themselves. We have constructed a phylogenic tree of 5 S rRNA sequences from fifteen plant chloroplasts. The result suggests that the emergence of algae occurred at an early stage of plant chloroplast evolution and that green plants originated from green algae. This is in agreement with the classical view and other theories of molecular evolution. However there is no common ancestor in the case of Bryophyta and ferns. Among the Angiospermae, a precise evolutionary process cannot be deduced because the Knuc values among the species are very close to each other.

Base Sequence↗
PubMed2002

Recurrent evolution of DNA-binding motifs in the Drosophila centromeric histone.

All eukaryotes contain centromere-specific histone H3 variants (CenH3s), which replace H3 in centromeric chromatin. We have previously documented the adaptive evolution of the Drosophila CenH3 (Cid) in comparisons of Drosophila melanogaster and Drosophila simulans, a divergence of approximately 2.5 million years. We have proposed that rapidly changing centromeric DNA may be driving CenH3's altered DNA-binding specificity. Here, we compare Cid sequences from a phylogenetically broader group of Drosophila species to suggest that Cid has been evolving adaptively for at least 25 million years. Our analysis also reveals conserved blocks not only in the histone-fold domain but also in the N-terminal tail. In several lineages, the N-terminal tail of Cid is characterized by subgroup-specific oligopeptide expansions. These expansions resemble minor groove DNA binding motifs found in various histone tails. Remarkably, similar oligopeptides are also found in N-terminal tails of human and mouse CenH3 (Cenp-A). The recurrent evolution of these motifs in CenH3 suggests a packaging function for the N-terminal tail, which results in a unique chromatin organization at the primary constriction, the cytological marker of centromeres.

Amino Acid Sequence↗
PubMed1987

[Acinar cell carcinoma of the salivary glands].

Between 1972 and 1985, eleven cases of acinic cell carcinoma were treated at the ENT clinic of the University Hospital Geneva. Eight of them were located in the parotid gland, three in minor salivary glands, two of these on the hard palate and one on the lower lip. Local recurrence occurred in four cases: two were recurrences of a parotid gland carcinoma and two of a minor salivary gland carcinoma. Three patients developed metastases, two in cervical lymph nodes and one in the lungs. Two tumours presented a very aggressive local development. Hence, the acinic cell carcinoma has a significant tendency to recur, to produce metastases, and may have an aggressive evolution. Radical treatment by surgery is necessary.

Adult↗
PubMed1986

The human tRNAVal gene family: organization, nucleotide sequences and homologous transcription of three single-copy genes.

At least 13 independent tRNAVal gene loci were detected in the human genome. Three of these genes were isolated and shown to occur only once in the haploid genome. No further functional tRNA genes are located on the isolated clones. Two tRNAVal genes encode the known major and minor tRNAVal isoacceptors, the third may be a pseudogene because a corresponding tRNAVal is not yet known. Comparison of extragenic sequences did not reveal significant homologies, indicating the separation of these genes early in vertebrate evolution. An Alu-type repeat was found in two of the clones within several hundred bp distance from the tDNA. All three genes are transcriptionally active in a HeLa nuclear extract. We show here for the first time that homologous in vitro transcription of mammalian tRNA genes strongly depends on extragenic control regions: interestingly, as a consequence of different flanking regions, the transcription efficiencies vary by an order of magnitude among the genes for the major and the minor tRNAVal and thus reflect the concentrations of these tRNAs in vivo.

Base Sequence↗
PubMed1996

Evolution in a chronic RNA virus infection: selection on HTLV-I tax protein differs between healthy carriers and patients with tropical spastic paraparesis.

HTLV-I causes T-cell leukemia and tropical spastic paraparesis (TSP) in a minority of infected people, whereas the majority remain healthy. The virus differs little in sequence between isolates but has been shown to have a quasispecies structure. Using the Nei and Gojobori algorithm, we have shown that the proportion of nonsynonymous to synonymous changes in HTLV-I proviral tax gene sequences from healthy seropositive subjects (Dn/Ds = 0.9 to 1.3) is significantly higher than those from TSP patients (Dn/Ds = 0.3 to 0.6). Here we show that the distinction between healthy seropositives and TSP patients can only be seen with proviral tax sequences, but not with cDNA, the amino-terminal or carboxy-terminal half of tax, or the rex gene. The Dn/Ds ratio of proviral tax sequences was used to analyze two TSP patients with atypical features and to investigate the influence of cytotoxic T cells (CTL) on the viral quasispecies.

Biological Evolution↗
PubMed1991

The changing faces of promotion and tenure at U.S. medical schools.

Faced with many potentially divisive questions related to tenure and promotion, leaders at medical schools have lacked an overview of examples of how other medical schools are adapting their faculty policies to reflect changing realities. This article reports results of a survey of U.S. medical school deans and of interviews with faculty affairs administrators regarding areas of change in faculty appointment, promotion, and tenure policies. Examples of adaptations are reported under the following headings: use of tenure; financial guarantees of tenure; criteria for award of tenure; probationary period; post-tenure review; advising faculty; clinician-educator tracks; and recruting women and minority faculty. Of these, the adaptation entailing the most activity and about which the most information was obtained concerns establishing a clinician-educator track. Numerous examples are provided of schools' evolutions of policies with regard to modifying titles of clinical-educators, defining promotion criteria, monitoring transfer between tracks, and defining contract periods, benefits, and privileges. The primary challenge for medical school administrators is to build sufficient flexibility into their promotion policies to show that the institution values the many different types of faculty needed, and at the same time to provide adequate security to essential faculty.

Career Mobility↗
PubMed2002

JC virus strains indigenous to northeastern Siberians and Canadian Inuits are unique but evolutionally related to those distributed throughout Europe and Mediterranean areas.

Human polyomavirus JC virus (JCV) isolates around the world are classified into more than 10 geographically distinct genotypes (designated as subtypes). Evolutionary relationships among JCV subtypes were recently examined, and the following pattern of JCV evolution was indicated. The ancestral JCV first divided into three superclusters, designated Types A, B, and C. A split in Type A generated two subtypes, EU-a and -b, containing mainly European and Mediterranean isolates. The split in Type B generated Af 2 (the major African subtype), Bl-c (a minor European subtype), and various Asian subtypes. Type C generated a single subtype (Afl), consisting of isolates derived from western Africa. In this study, JCV isolates prevalent among northeastern Siberians and Canadian Inuits were evaluated in the context of the above-described pattern of JCV evolution. The Siberian/Arctic JCV isolates were classified as belonging mainly to Type A, based on the result of a preliminary phylogenetic analysis. We then examined, using the whole-genome approach, the phylogenetic relationships among worldwide Type A isolates. In neighbor-joining and maximum-likelihood analyses, Type A JCVs worldwide consistently diverged into three subtypes, EU-a, -b, and -c, with high bootstrap probabilities. EU-c was constructed only by northeastern Siberian isolates, derived mainly from Nanais living in the lower Amur River region, and was shown to have been generated by the first split in Type A. Most Siberian/Arctic isolates derived from Chukchis, Koryaks, and Canadian Inuits formed a distinct cluster within the EU-a subtype, with a high bootstrap probability. Based on the present findings, we discuss ancient human migrations, accompanied by Type A JCVs, across Asia and to Arctic areas of North America.

Adult↗
PubMed1989

Cytogenetic analysis of in vitro karyotype evolution in a cell line established from nonmalignant human mammary epithelium.

Cytogenetic analysis was carried out on six passages (pass. 16, 19, 21, 25, 34, and 47) of the nontumorigenic epithelial cell line, HMT-3522, established from a fibrocystic lesion of the human breast. Minor chromosome abnormalities were present in the first passage (pass. 16) available for study, and limited cytogenetic progression was observed during the in vitro growth. A modal chromosome number of 45 chromosomes was found in all passages. Each passage contained 4-5 marker chromosomes. Three markers were consistently present in all passages studied. During in vitro growth two markers were gained and two markers were lost from the stemline karyotype. The two latest passages studied had identical karyotypes: 45,XX, del(1)(q44----p32:),t(5;14)(14p13----14q32::5q22----++ +5q35),t(6;8;12;17)(8p23---- 8q24::6p21.1----6p23;12q24----12p13::6p23- --- 6p25;17p13----17q25::6q11----6q27). The present study demonstrates chromosome abnormalities and karyotypic evolution in a nontumorigenic (in nude mice) and noninvasive (in vitro tested) cell line established from nonmalignant epithelial breast tissue. The results are discussed in relation to gene amplification, double minutes and oncogene localization.

Breast↗
PubMed1986

Viral sequences are associated with many histocompatibility genes.

A C57BL/6By 5.5 kb Pvu II polymorphic restriction fragment which hybridizes with a spleen focus-forming env probe and maps in the H-30 region has been cloned, and a 358 bp subfragment subcloned. Hybridization and sequencing studies show that the 358 bp fragment is encoded by the region of the pol gene of murine retrovirus which codes for an endonuclease critical for viral integration. Hybridizations of digested murine genomic DNAs with the 358 bp probe generate 31 restriction fragment length polymorphisms (RFLPs); 16 of these can be placed near the following 15 minor histocompatability (H) loci: H-3, H-4, H-7, H-13, H-15, H-16, H-17, H-19, H-22, H-24, H-27, H-30, H-34, H-36, and H-38. We suggest that the proximity of viral sequences to H loci is probably evolutionarily and functionally significant and that the closeness of viral sequences and minor H loci can probably be utilized to facilitate the cloning of minor H genes. During the course of these studies, it has become possible to tentatively assign H-17, H-34, and H-38 to chromosome 12. In addition, it was observed that several H-2 congenic strains retain portions of chromosome 12 from the parental donor strains used in their derivation.

Animals↗
PubMed1993

How much do we know about spontaneous human mutation rates?

The much larger number of cell divisions between zygote and sperm than between zygote and egg, the increased age of fathers of children with new dominant mutations, and the greater evolution rate of pseudogenes of the Y chromosome than of those on autosomes all point to a much higher mutation rate in human males than in females, as first pointed out by Haldane [Ann Eugen 13:262-271, 1947] in his classical study of X-linked hemophilia. The age of the father is the main factor determining the human spontaneous mutation rate, and probably the total mutation rate. The total mutation rate in Drosophila males of genes causing minor reduction in viability is at least 0.4 per sperm, and may be considerably higher. The great mutation load implied by a rate of approximately 1 per zygote can be greatly ameliorated by quasi-truncation selection. Corresponding data are not available for the human population. The evolution rate of pseudogenes in primates suggests some 10(2) new mutations per zygote. Presumably the overwhelming majority of these are neutral, but even the approximate fraction is not known. Statistical evidence in Drosophila shows that mutations with minor effects cause about the same heterozygous impairment of fitness as those that are lethal when homozygous. The magnitude of heterozygous effect is such that almost all mutant genes are eliminated as heterozygotes before ever becoming homozygous. Although quantitative data in the human species are lacking, anecdotal information supports the conclusion that partial dominance is the rule here as well. This suggests that if the human mutation rate were increased or decreased, the effects would be spread over a period of 50-100 generations.

Age Factors↗
PubMed2006

Sex chromosomes and male ornaments: a comparative evaluation in ray-finned fishes.

Theory predicts that the mechanism of genetic sex determination can substantially influence the evolution of sexually selected traits. For example, female heterogamety (ZZ/ZW) can favour the evolution of extreme male traits under Fisher's runaway model of sexual selection. We empirically test whether the genetic system of sex determination has played a role in the evolution of exaggerated male ornaments in actinopterygiian fishes, a clade in which both female-heterogametic and male-heterogametic systems of sex determination have evolved multiple times. Using comparative methods both uncorrected and corrected for phylogenetic non-independence, we detected no significant correlation between sex-chromosome systems and sexually selected traits in males. Results suggest that sex-determination mechanism is at best a relatively minor factor affecting the outcomes of sexual selection in ray-finned fishes.

Animals↗