Hormone profiles in hormone-dependent cancers.
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Studies on the relationship of urinary excretion of androgen metabolites and estrogens to the natural history of breast cancer are reviewed. The importance of distinguishing between "within-population" studies (i.e., cancer patients versus normal controls) and "between populations" studies (i.e., low-risk versus high-risk populations) is emphasized, and it is pointed out that "qualitative" agreement (i.e. the same direction of differences) between the two types of studies must be present in order to implicate a hormonal parameter as a determinant of the natural history of breast cancer. For reasons detailed in this paper, it is concluded that the reported relationship of low urinary androgen metabolite excretion to increased risk of developing breast cancer and poor response to adrenalectomy or hypophysectomy and the validity of the "estriol hypothesis," namely, that a high urinary ratio of estriol to estrone-plus-estradiol in early life is protective against subsequent development of breast cancer, are both dubious. A new hypothesis concerning the relationship of estrogens to breast cancer risk is presented: "A period of of time, prior to age 30, during which the amount of biological availability of active estrogens' (i.e., estrone and estradiol) is diminished, protects against subsequent development of cancer." This hypothesis is shown to be compatible with the epidemiological and biochemical data. Reports concerning the influence of nutrition on endocrine parameters are reviewed. Inanition and obesity have been shown to alter steroid metabolism but it is not known whether nutritional "microdifferences" (i.e., differences between populations or individuals that are due to cultural, geographic, or socioeconomic factors, but that fall within the range of "normal" or adequate nutrition) can also alter steroid metabolism. (+info)
Detection of chelonid herpesvirus DNA by nonradioactive in situ hybridization in tissues from tortoises suffering from stomatitis-rhinitis complex in Europe and North America.
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Chelonid herpesvirus (ChHV) infection in tortoises associated with stomatitis-rhinitis complex is a severe, mostly epizootic disease characterized by proliferative and diphtheroid-necrotizing glossitis, pharyngitis, rhinitis, and tracheitis, often occurring with pneumonia and encephalitis. The UL5 gene from a German ChHV isolate was used to generate a digoxigenin-labeled 307-base-pair DNA probe by polymerase chain reaction (PCR). ChHV DNA was detected in paraffin-embedded tissues of five naturally infected tortoises (two Afghan tortoises [Testudo horsfieldii], USA; two Hermann's tortoises [Testudo hermanni], Switzerland; one T. hermanni, Germany) by means of in situ hybridization (ISH) and PCR. Distribution of ChHV DNA exhibits many characteristics of alphaherpesvirus but also some characteristics of betaherpesvirus infections. The amino acid sequence of a portion of the ChHV UL5 homolog exhibited more than 50% similarity to alphaherpesvirus UL5 proteins. Nuclear hybridization signals were detected in epithelial cells of the lingual mucosa and glands. Furthermore, ChHV DNA was observed in tracheal epithelium, pneumocytes, hepatocytes, the renal tubular epithelium, cerebral glia cells and neurons, and intramural intestinal ganglia. ChHV DNA in endothelial cells of many organs underlines the systemic character of the disease. Importantly, ChHV DNA was detected by ISH in multiple tissues of tortoises originating from different geographic provenances. This indicates a high degree of conservation of the UL5 gene fragment among viruses prevalent in tortoises on different continents. With the described ISH, a molecular biological tool is available for rapid and specific diagnosis of ChHV infections and, more importantly, comparative pathogenetic studies of ChHV isolates from geographically unrelated regions. (+info)
Frameshift mutations in rdxA and metronidazole resistance in North American Helicobacter pylori isolates.
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In Helicobacter pylori, the oxygen-insensitive nitroreductase RdxA is likely to activate metronidazole (Mtz) by reduction and formation of cytotoxic intermediates. Mutations in rdxA have been associated with Mtz resistance in H. pylori. In vitro Mtz susceptibilities of 17 randomly selected H. pylori isolates were determined by the agar dilution method. DNA sequence analysis of rdxA alleles of eight susceptible isolates (MIC range: 0.25-1.0 mg/L) and nine resistant isolates (MIC range: 16-256 mg/L) showed that six of nine Mtz-resistant H. pylori isolates contained insertion or deletion mutations ('indel' mutations). One isolate contained a substitution mutation at codon position 148 that resulted in the introduction of a premature stop codon. Creation of stop codons within the rdxA coding sequence by either frameshift or substitution mutations resulted in premature translation termination and expression of putatively truncated RdxA polypeptides. (+info)
Highly active antiretroviral therapy and incidence of cancer in human immunodeficiency virus-infected adults.
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BACKGROUND: The risk of Kaposi's sarcoma and non-Hodgkin's lymphoma is increased in people infected with the human immunodeficiency virus-1 (HIV). Highly active antiretroviral therapy (HAART) has been widely used by HIV-infected people in North America, Europe, and Australia since about 1997. Acquired immunodeficiency syndrome (AIDS) incidence and mortality rates have fallen markedly in association with the use of HAART, but its impact on the incidence of cancer in HIV-infected people is less clear. METHODS: Cancer incidence data from 23 prospective studies that included 47 936 HIV-seropositive individuals from North America, Europe, and Australia were collated, checked, and analyzed centrally. Adjusted incidence rates (expressed as number of cancers per 1000 person-years) for Kaposi's sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease, cervical cancer, and 20 other cancer types or sites were calculated. Rate ratios were estimated, comparing incidence rates from 1997 through 1999 with rates from 1992 through 1996, after adjustment for study, age, sex, and HIV transmission group. All statistical tests were two-sided. RESULTS: For the period from 1992 through 1999, 2702 incident cancers were reported in 138 148 person-years of observation, and more than 90% of them were either Kaposi's sarcoma or non-Hodgkin's lymphoma. The adjusted incidence rate for Kaposi's sarcoma declined from 15.2 in 1992 through 1996 to 4.9 in 1997 through 1999 (rate ratio = 0.32; 99% confidence interval [CI] = 0.26-0.40; based on 1489 and 190 cases, respectively; P<.0001). The incidence rates for non-Hodgkin's lymphoma also declined, from 6.2 to 3.6 (rate ratio = 0.58; 99% CI = 0.45-0.74; based on 623 and 134 cases, respectively; P<.0001). Among the lymphomas, the rate ratios were 0.42 (99% CI = 0.24-0.75) for cerebral lymphoma, 0.57 (99% CI = 0.39-0.85) for immunoblastic lymphoma, and 1.18 (99% CI = 0.48-2.88) for Burkitt's lymphoma (chi(2)(2) for heterogeneity = 6.2; P: =.05). There was no statistically significant change in the incidence rates for Hodgkin's disease (rate ratio = 0.77; 99% CI = 0.32-1.85; based on 38 and 12 cases, respectively; P =.4) or for cervical cancer (rate ratio = 1.87; 99% CI = 0.77-4.56; based on 19 and 17 cases, respectively; P =.07). The adjusted incidence rate for all other cancers combined was 1.7 in each time period (rate ratio = 0.96; 99% CI = 0.62-1.47; based on 126 and 54 cases, respectively). CONCLUSIONS: Since the widespread use of HAART, there have been substantial reductions in the incidence Kaposi's sarcoma and non-Hodgkin's lymphoma in HIV-infected people but, so far, no substantial change in the incidence of other cancers. (+info)
Two new mechanisms of macrolide resistance in clinical strains of Streptococcus pneumoniae from Eastern Europe and North America.
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Resistance to macrolides in pneumococci is generally mediated by methylation of 23S rRNA via erm(B) methylase which can confer a macrolide (M)-, lincosamide (L)-, and streptogramin B (S(B))-resistant (MLS(B)) phenotype or by drug efflux via mef(A) which confers resistance to 14- and 15-membered macrolides only. We studied 20 strains with unusual ML or MS(B) phenotypes which did not harbor erm(B) or mef(A). The strains had been isolated from patients in Eastern Europe and North America from 1992 to 1998. These isolates were found to contain mutations in genes for either 23S rRNA or ribosomal proteins. Three strains from the United States with an ML phenotype, each representing a different clone, were characterized as having an A2059G (Escherichia coli numbering) change in three of the four 23S rRNA alleles. Susceptibility to macrolides and lincosamides decreased as the number of alleles in isogenic strains containing A2059G increased. Sixteen MS(B) strains from Eastern Europe were found to contain a 3-amino-acid substitution ((69)GTG(71) to TPS) in a highly conserved region of the ribosomal protein L4 ((63)KPWRQKGTGRAR(74)). These strains formed several distinct clonal types. The single MS(B) strain from Canada contained a 6-amino-acid L4 insertion ((69)GTGREKGTGRAR), which impacted growth rate and also conferred a 500-fold increase in MIC on the ketolide telithromycin. These macrolide resistance mechanisms from clinical isolates are similar to those recently described for laboratory-derived mutants. (+info)
Extensive amino acid polymorphism at the pgm locus is consistent with adaptive protein evolution in Drosophila melanogaster.
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PGM plays a central role in the glycolytic pathway at the branch point leading to glycogen metabolism and is highly polymorphic in allozyme studies of many species. We have characterized the nucleotide diversity across the Pgm gene in Drosophila melanogaster and D. simulans to investigate the role that protein polymorphism plays at this crucial metabolic branch point shared with several other enzymes. Although D. melanogaster and D. simulans share common allozyme mobility alleles, we find these allozymes are the result of many different amino acid changes at the nucleotide level. In addition, specific allozyme classes within species contain several amino acid changes, which may explain the absence of latitudinal clines for PGM allozyme alleles, the lack of association of PGM allozymes with the cosmopolitan In(3L)P inversion, and the failure to detect differences between PGM allozymes in functional studies. We find a significant excess of amino acid polymorphisms within D. melanogaster when compared to the complete absence of fixed replacements with D. simulans. There is also strong linkage disequilibrium across the 2354 bp of the Pgm locus, which may be explained by a specific amino acid haplotype that is high in frequency yet contains an excess of singleton polymorphisms. Like G6pd, Pgm shows strong evidence for a branch point enzyme that exhibits adaptive protein evolution. (+info)
A mixed-model approach to mapping quantitative trait loci in barley on the basis of multiple environment data.
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In this article, I propose a mixed-model method to detect QTL with significant mean effect across environments and to characterize the stability of effects across multiple environments. I demonstrate the method using the barley dataset by the North American Barley Genome Mapping Project. The analysis raises the need for mixed modeling in two different ways. First, it is reasonable to regard environments as a random sample from a population of target environments. Thus, environmental main effects and QTL-by-environment interaction effects are regarded as random. Second, I expect a genetic correlation among pairs of environments caused by undetected QTL. I show how random QTL-by-environment effects as well as genetic correlations are straightforwardly handled in a mixed-model framework. The main advantage of this method is the ability to assess the stability of QTL effects. Moreover, the method allows valid statistical inferences regarding average QTL effects. (+info)
Growth in North American white children with neurofibromatosis 1 (NF1).
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OBJECTIVE: To analyse the distributions of and generate growth charts for stature and occipitofrontal circumference (OFC) in neurofibromatosis 1 (NF1) patients. DESIGN: Cross sectional database survey. SETTING: The National Neurofibromatosis Foundation International Database (NFDB) includes clinical information on NF1 patients from 14 participating centres in North America. SUBJECTS: A total of 569 white, North American, NF1 patients, 55% female and 45% male. MAIN OUTCOME MEASURES: Stature and OFC measurements of NF1 patients were compared to age and sex matched population norms using z score standardisation and centile curves. RESULTS: The distributions of stature and OFC are shifted and unimodal among NF1 patients; 13% of patients have short stature (>/=2 standard deviations below the population mean) and 24% have macrocephaly (OFC >/=2 standard deviations above the population mean). CONCLUSIONS: Alterations of stature and OFC are not limited to NF1 patients with frank short stature or macrocephaly. (+info)