Endothelial Damage in Sepsis: The Importance of Systems Biology.

The early diagnosis and appropriate stratification of sepsis continues to be one of the most important challenges in modern medicine. Single isolated biomarkers have not been enough to improve diagnostic and prognostic strategies and to progress toward therapeutic goals. The information generated by the human genome project has allowed a more holistic approach to the problem. The integration of genomics, transcriptomics, proteomics and metabolomics in sepsis has allowed us to progress in the knowledge of new pathways which are pathophysiologically involved in this disease. Thus, we have understood the importance of and complex interaction between the inflammatory response and the endothelium. Understanding the role of important parts of the microcirculation, such as the endothelial glycocalyx and its interaction with the inflammatory response, has provided early recognition elements for clinical practice that allow the rational use of traditional medical interventions in sepsis. This comprehensive approach, which differs from the classical mechanistic approach, uses systems biology to increase the diagnostic and prognostic spectrum of endothelial damage biomarkers in sepsis, and to provide information on new pathways involved in the pathophysiology of the disease. This, in turn, provides tools for perfecting traditional medical interventions, using them at the appropriate times according to the disease's pathophysiological context, while at the same time discovering new and improved therapeutic alternatives. We have the challenge of transferring this ideal scenario to our daily clinical practice to improve our patients' care. The purpose of this article is to provide a general description of the importance of systems biology in integrating the complex interaction between the endothelium and the inflammatory response in sepsis.

Deposits in the lungs of Kwäday Dän Ts'ìnchi man: Characterization by a combination of analytical microscopical methods.

OBJECTIVES: The approximately 250 years old remains of the Kwäday Dän Ts'ìnchi man were found in a glacier in Canada. Studying the state of preservation of the corpse, we observed black deposits in his lung. Following this observation we wanted to determine: (1) location of the deposits in the lung tissue, (2) composition and origins of the deposits. METHODS: By light microscopy (LM) and transmission electron microscopy (TEM), we studied the deposits in the Kwäday Dän Ts'ìnchi man' s lung and compared it with distribution of anthracotic deposits in contemporary samples from the David Harwick Pathology Centre (DHPC). To determine chemical composition of the inclusions we used Raman spectroscopy. Scanning electron microscopy and elemental mapping was used for determine the chemical elements. RESULTS: The histopathological identification of anthracosis in the Kwäday Dän Ts'ìnchi man's lung allowed us to distinguish crushed parenchyma from conducting airway tissue and identification of particles using LM and TEM. Crystal particles were found using TEM. Ordered carbonaceous material (graphene and graphite), disordered carbonaceous material (soot) and what might be minerals (likely conglomerates) were found with Raman spectrometry. Gold and lead particles in the lung were discovered with scanning electron microscopy and elemental mapping. CONCLUSIONS: Presence of soot particles in anthracotic areas in the Kwäday Dän Ts'ìnchi man's lung probably were due to an inhalation of particles in open fires. Gold and lead particles are most likely of an environmental origin and may have been inhaled and could have impacted his health and his Champagne and Aishihik First Nations (CAFN) contemporaries.

Free software to analyse the clinical relevance of drug interactions with antiretroviral agents (SIMARV®) in patients with HIV/AIDS.

BACKGROUND: Highly active antiretroviral therapy has extended the expected lifespan of patients with HIV/AIDS. However, the therapeutic benefits of some drugs used simultaneously with highly active antiretroviral therapy may be adversely affected by drug interactions. OBJECTIVE: The goal was to design and develop a free software to facilitate analysis, assessment, and clinical decision making according to the clinical relevance of drug interactions in patients with HIV/AIDS. METHODS: A comprehensive Medline/PubMed database search of drug interactions was performed. Articles that recognized any drug interactions in HIV disease were selected. The publications accessed were limited to human studies in English or Spanish, with full texts retrieved. Drug interactions were analyzed, assessed, and grouped into four levels of clinical relevance according to gravity and probability. Software to systematize the information regarding drug interactions and their clinical relevance was designed and developed. RESULTS: Overall, 952 different references were retrieved and 446 selected; in addition, 67 articles were selected from the citation lists of identified articles. A total of 2119 pairs of drug interactions were identified; of this group, 2006 (94.7%) were drug-drug interactions, 1982 (93.5%) had an identified pharmacokinetic mechanism, and 1409 (66.5%) were mediated by enzyme inhibition. In terms of clinical relevance, 1285 (60.6%) drug interactions were clinically significant in patients with HIV (levels 1 and 2). With this information, a software program that facilitates identification and assessment of the clinical relevance of antiretroviral drug interactions (SIMARV®) was developed. CONCLUSIONS: A free software package with information on 2119 pairs of antiretroviral drug interactions was designed and developed that could facilitate analysis, assessment, and clinical decision making according to the clinical relevance of drug interactions in patients with HIV/AIDS.

Factors associated with health-related quality of life in a cohort of Spanish breast cancer patients.

BACKGROUND: Several factors can modify health-related quality of life (HRQOL) of breast cancer survivors. The objective of the current study was to analyse the associations between HRQOL scores 1 year after breast cancer surgery and sociodemographic and clinical factors. METHODS: This was an observational, multicentre and prospective study of a cohort of patients who underwent oncological breast cancer surgery and which was followed up for 1 year. The HRQOL was assessed at 1 year after surgery using three questionnaires: EuroQol-5D, EORTC QLQ-C30 and its breast-specific module BR-23. RESULTS: A total of 364 patients participated in the study. Some factors were associated with better HRQOL 1 year after surgery: age between 60 and 69 years and under 50 years, being single or a housewife, stage I-II, invasive papillary carcinoma, breast-conserving surgery (BCS) or lack of axillary dissection. However, only the following were independent predictive factors: being single or a housewife, BCS, invasive papillary carcinoma, coming from an outpatient clinic or not receiving radiotherapy. Further, some factors were independent predictors of a worse HRQOL: age over 70 years, being married, separated or widowed, stage III or not receiving adjuvant chemotherapy. CONCLUSIONS: Demographic and clinical factors can influence HRQOL, some of them independently.

[Hypolipidemic agents drug interactions: approach to establish and assess its clinical significance. Structured review]. / Interacciones medicamentosas de agentes hipolipemiantes: aproximación para establecer y valorar su relevancia clínica. Revisión estructurada.

OBJECTIVE: To carry out a structures review of drug interactions of hypolipidemic drugs and to assess their clinical relevance. METHOD: Structured review of drug interactions of hypolipidemic drugs in humans through PubMed/Medline of published articles, without language restrictions and with full text access until June 30th of 2012. The following Mesh terms were used: Drug Interactions, Lipid Regulating Agents, Herb-Drug Interactions, Food-Drug Interactions y Hypolipidemic Agents (Pharmacological Action). The information was completed with those articles considered to be relevant. Finally, a method was used to assess the clinical relevance of the interaction, based on the likelihood of occurrence and the severity of the effect of the interaction. RESULTS: 849 publications were gathered, of which 243 references were selected, among which 189 interactions were identified. Thirty-three of them were considered of very high risk (level 1) and 42 of high risk (level 2), basically associated to increased risk for rhabdomyolisis. Enzymatic inhibition of CYP450 was the most common mechanism for these interactions. CONCLUSIONS: Of the interactions identified in patients on hypolipidemic drugs, 60.3% (128/189) are clinically relevant (very high or high risk), mainly associated to the occurrence of rhabdomyolisis. Most of these interactions are attributed to simultaneous use of CYP3A4 inhibitors. Therefore, statins metabolized through CYP3A4 (simvastatin, lovastatin and atorvastatin) are the ones with the highest number of clinically relevant interactions.

Objetivo: Realizar una revisión estructurada sobre interacciones medicamentosas de los hipolipemiantes y valorar su relevancia clínica. Método: Revisión estructurada de interacciones medicamentosas con hipolipemiantes en humanos, en PubMed/Medline de artículos publicados sin restricción de idioma, con acceso a texto completo hasta junio 30 de 2012. La búsqueda se realizó con los siguientes terminos Mesh: Drug Interactions, Lipid Regulating Agents, Herb-Drug Interactions, Food-Drug Interactions y Hypolipidemic Agents (Pharmacological Action). La información se complementó con artículos considerados importantes. Por último, se utilizó un método para evaluar la relevancia clínica de la interacción, basado en la probabilidad de ocurrencia y en la gravedad del efecto de la interacción. Resultados: Se obtuvieron 849 publicaciones, de las cuales se seleccionaron 243 referencias, en las los que se identificaron 189 interacciones. De ellas 33 fueron valoradas como de riesgo muy alto (nivel 1) y 42 de riesgo alto (nivel 2), asociadas fundamentalmente al aumento del riesgo de rabdomiólisis. La inhibición enzimática de la CYP450 fue el mecanismo más común de las interacciones. Conclusiones. En los pacientes en tratamiento con hipolipemiantes, de las interacciones identificadas 60,3% (128/189) son clínicamente relevantes (riesgo muy alto o alto), asociadas principalmente a la aparición de rabdomiólisis. La mayoría de dichas interacciones son atribuidas al uso simultáneo de reconocidos inhibidores de la CYP3A4. Por ello, las estatinas metabolizadas por la CYP3A4 (simvastatina, lovastatina y atorvastatina) son las que más interacciones de relevancia clínica presentan.

Evolution of Health-Related Quality of Life in Breast Cancer Patients during the First Year of Follow-Up.

PURPOSE: The objective of this study was to describe the evolution of health-related quality of life (HRQOL) in a cohort of breast cancer patients over 1 year after surgery and to analyse the predictive ability of HRQOL measurement instruments. METHODS: Observational, multicenter and prospective study of a cohort of breast cancer patients, assessing HRQOL at 1, 6, and 12 months after surgery using three questionnaires: EuroQol-5D-3L, EORTC QLQ-C30, and EORTC QLQ-BR23. RESULTS: A total of 364 women participated in the study. Visual Analogue Scale (VAS) scores from the EuroQol improved (1 month vs. 1 year: 70 vs. 80; p<0.0001); however, the EuroQol score showed no significant change (0.81 vs. 0.83; p=0.1323). In contrast, Global Health Status on the EORTC QLQ-C30 improved (66.67 vs. 100.00; p<0.0001), as did all of this instrument's scales and most of its independent items. The EORTC QLQ-BR23 dimensions showed improvement, except for sexual functioning (100.00 vs. 86.67; p=0.0030) and future perspective (33.33 vs. 66.67; p<0.0001). Patients with good HRQOL outcomes at 1 month showed improved levels of HRQOL at 1 year; HRQOL measured at 1 month was predictive of HRQOL at 1 year. CONCLUSION: HRQOL improved during the follow-up period. Likewise, HRQOL measurement instruments can predict early HRQOL.

[Approach to establishing and evaluating clinical relevance of drug interactions in HIV patients: 2009 update]. / Aproximación para establecer y evaluar la relevancia clínica de las interacciones medicamentosas en pacientes infectados con virus de la inmunodeficiencia humana: actualización 2009.

OBJECTIVE: To update information on drug interactions in patients with HIV/AIDS. METHOD: PubMed was used to review English and Spanish articles published between 1 July 2007 and 30 April 2009 on antiretroviral drug interactions in humans. The search included a review of interactions between commonly-used medications in patients with HIV/AIDS and references from articles considered to be relevant. RESULTS: 52 new interactions were identified having to do with CYP3A4 metabolism and competition for intestinal absorption. New pharmacokinetic interactions were identified for medications that were already on the market, and we report interactions for drugs that were recently introduced: Tipranavir, Fosamprenavir, Darunavir, Raltegravir, Maraviroc and Etravirine. CONCLUSIONS: There is evidence of 52 new interactions between medications using metabolic routes in the CYP450 enzymatic system, and an explanation is given for others in the intestinal absorption process.

Effect of zinc replacement on lipids and lipoproteins in type 2-diabetic patients.

Abnormal zinc and lipid plasma levels occur more frequently in metabolically uncontrolled diabetic patients. These lipid alterations are key factors in the emergence of microvascular complications, which lead to death in those patients. Yet, zinc sulfate supplementation may be a therapeutical resource to recover some functioning and improve life span. This article reports the assessment of lipid profile from type 2-diabetes mellitus patients treated with hypoglycemic therapy drugs, who additionally presented zinc levels lower than average in Mexican reference. The patients received a 100 mg zinc sulfate treatment in a crossover double-blind design of clinically controlled study with starch as placebo. The diabetic patients had changes in their lipid profile after a 12-week zinc treatment as compared with placebo treatment. The 100 mg zinc sulfate treatment was well tolerated, significantly reduced total cholesterol and triglyceride concentrations, and increased those corresponding to zinc as well as HDL cholesterol in the bloodstream. Thus, using this treatment the cardiovascular involvement is expected to decrease in the type 2-diabetes mellitus patients, especially those with myocardial infarction and stroke, which are the main death causes in Mexico.

Correlation between serum leptin levels and insulin sensitivity in diffuse toxic goiter.

OBJECTIVE: The aim of this survey was to assess the correlation between leptin and insulin sensitivity (IS) in cases of diffuse toxic goiter. DESIGN, PATIENTS, MEASUREMENTS: This is a descriptive study on patients with diffuse toxic goiter (DTG) assessing their body mass index (BMI), serum leptin concentrations, circulating insulin (area under the curve (AuC) of insulin), average insulin level, thyroid hormones, thyroid stimulating hormone (TSH), glycemia and IS (using a hyperinsulinemic-euglycemic clamp and the homeostasis model for assessment of insulin resistance (HOMA-IR) before and after euthyroidism induced with metimazol. RESULTS: The average patient age was 35 years old (range 31-40 years), height was 157 cm (range 151-160 cm), glycemia was 4.3 +/- 0.3 mmol/L and TSH 0.1 +/- 0.1 microU/mL. Average leptin level was 11.3 +/- 2.8 ng/dL, the average insulin level was 10.13 +/- 3.7 mIU/mL and the AuC for insulin was 50.6 +/- 18 microIU x min/mL. No correlation was found between leptin and BMI, thyroid hormones and glycemia. While controlling for the BMI effect, a correlation was found between leptin and TSH (r = -0.77, p = 0.042), as well as between leptin and insulinemia (r = 0.93, r2 = 0.86, p = 0.001) independently from the state of thyroid function. There was a tendency for a high correlation between leptin and the insulin AuC (hyperthyroidism: r = 0.89, p = 0.056; euthyroidism: r = 0.99, p = 0.056). A negative correlation was found between IS and the insulin AuC (rho = -0.58, p = 0.18). There was a high tendency for correlation between leptin and IS when the BMI effect (HOMA-IR: r = 0.70, p = 0.12; PHE: r = -0.55, p = 0.26) was taken into consideration. CONCLUSIONS: There is a high tendency for a negative correlation between leptin and IS when the BMI effect is controlled. There is a high tendency for a positive correlation between leptin and insulin and TSH.

Selective pressure has not acted against hypercoagulability alleles in high-altitude Amerindians.

Elevated hematocrit increases blood oxygen carrying capacity in high-altitude populations, but blood viscosity and coaguability may increase concomitantly. Alleles of the beta-fibrinogen gene (FGB) associated with lower fibrinogen levels are more common in highland Amerindians (Quechua) than lowland Amerindians (Na-Dene). Although genetic drift could account for this, selection may have acted against transmission of hypercoagulability alleles at high altitude. To test this hypothesis, we compared allele frequencies between Quechua and more closely related lowlanders (Maya) at loci in the genes encoding beta-fibrinogen (FGB), factors V (F5), VII (F7) and XIII (F13), alpha2-integrin (ITGA2) and plasminogen activator inhibitor type 1 (PAI-1; SERPINE1). No significant differences in allele frequencies were found except 485arg in the gene encoding factor V, which was more common in the Quechua. These data do not support the hypothesis that selection has acted to eliminate alleles associated with hypercoagulability in Andean highlanders.

Methylenetetrahydrofolate reductase (MTHFR) allele frequencies in Amerindians.

Neural tube defects (NTDs) have been associated with abnormalities of folate metabolism. Methylenetetrahydrofolate reductase (MTHFR) is the regulatory enzyme for the conversion of homocysteine to methionine. The C677T mutation in the MTHFR gene affects folate distribution, and homozygosity for the T allele may be associated with an increased risk of NTDs. A second mutation, an A1298C transversion in this same gene, is also associated with an increased risk for NTDs but only in conjunction with the 677T allele. A low incidence of NTDs has been observed in high-altitude populations; however, these studies did not provide information about the allele distribution of genes involved in folate metabolism. This investigation compares allele frequencies of the C677T and A1298C polymorphisms between Quechua people living at 3200-4200 m in the Peruvian Central Andes and an Aché group living at low altitude. Allele frequencies at both loci were not significantly different between the two populations. The absence of the 677T/677T genotypes and of the 677T/1298C arrangement in both groups may indicate a genetic contribution to reduced risk for NTDs; however, factors other than altitude are likely responsible for the low variant allele frequencies in these populations.

Genetic polymorphisms in the Renin-Angiotensin system in high-altitude and low-altitude Native American populations.

Cardiovascular disease (CVD) is reportedly less common in high-altitude native populations than in lowlanders. To some extent, this is due to cultural and demographic factors; however, increased cardiovascular efficiency contributing to hypoxia adaptation may also be involved. Numerous genetic variants have been associated with cardiovascular health. If the decreased incidence of CVD in modern high-altitude populations reflects selective pressures having favoured the transmission of these alleles in their antecedents, it would be expected that these alleles would be more common in highlanders than in lowlanders. We tested this hypothesis by determining the allele frequencies of five polymorphic loci in genes encoding components of the renin-angiotensin system (RAS) that have alleles associated with hypertension and cardiovascular disease in a high-altitude native Andean population, Quechua from the Peruvian altiplano, and in a lowland Amerindian population, Maya from the Yucatan peninsula. The polymorphisms examined were 1) the insertion/deletion polymorphism in intron 16 of the angiotensin converting enzyme (ACE) gene; 2) the A/G2350 transition (ACE-8) in intron 17 of the ACE gene; 3) the A/C1166 transversion in the 3' untranslated region of the angiotensin II receptor (type 1) gene (AGTR1); 4) the G/AI9-83 transition in intron 8 of the renin gene (REN); and 5) the T/C704 (Met235Thr) transition mutation in angiotensinogen (AGT). There was no evidence for an over-representation of the RAS alleles associated with cardiovascular fitness in the high-altitude Amerindian population when compared to the lowland Amerindian population.

Brief communication: molecular analysis of the Kwäday Dän Ts'finchi ancient remains found in a glacier in Canada.

DNA was extracted from the frozen remains of a man found in the northwest corner of British Columbia, Canada, in 1999. His clothing was radiocarbon-dated at ca. 550 years old. Nitrogen and carbon content in whole bone and collagen-type residue extracted from both bone and muscle indicated good preservation of proteinaceous macromolecules. Restriction enzyme analysis of mitochondrial DNA (mtDNA) determined that the remains belong to haplogroup A, one of the four major Native American mtDNA haplogroups. Data obtained by PCR direct sequencing of the mtDNA control region, and by sequencing the clones from overlapping PCR products, were duplicated by an independent laboratory. Comparison of these mtDNA sequences with those of North American, Central American, South American, East Siberian, Greenlandic, and Northeast Asian populations indicates that the remains share an mtDNA type with North American, Central American, and South American populations.

A Mutation in the C-terminal domain of the RNA polymerase alpha subunit that destabilizes the open complexes formed at the phage phi 29 late A3 promoter.

Regulatory protein p4 from Bacillus subtilis phage phi29 activates the viral late A3 promoter mainly by stabilizing the binding of RNA polymerase (RNAP) to it as a closed complex. This requires an interaction between protein p4 residue Arg120 and the C-terminal domain (CTD) of the RNAP alpha subunit. Several acidic residues of the alpha-CTD, considered as plausible targets for p4 residue Arg120, were individually changed into alanine. In addition, a truncated alpha subunit lacking the last four residues, two of which are acidic, was obtained. The modified alpha subunits were purified and reconstituted into RNAP holoenzyme in vitro. Protein p4 was found to be unable to activate the late A3 promoter when residue Glu297 of the alpha subunit was changed to Ala, a modification that did not impair transcription from several other promoters. Interestingly, protein p4 could stabilize the modified RNAP at the A3 promoter as a closed complex, although the open complexes formed were unstable and did not proceed to elongation complexes. Our results indicate that the change of the alpha residue Glu297 into Ala destabilizes the open complexes formed at this promoter, but not at other promoters. Considered in the context of earlier findings indicating that the RNAP alpha-CTD may participate in the transition from closed to intermediate complexes at some other promoters, the new results expand and clarify our view of its role in transcription initiation.

Direct coupling of transcription and mRNA processing through the thermogenic coactivator PGC-1.

Transcription and mRNA processing are coupled events in vivo, but the mechanisms that coordinate these processes are largely unknown. PGC-1 is a transcriptional coactivator that plays a major role in the regulation of adaptive thermogenesis. PGC-1 also has certain motifs characteristic of splicing factors. We demonstrate here that mutations in the serine- and arginine-rich domain and RNA recognition motif of PGC-1 interfere with the ability of PGC-1 to induce mRNAs of target genes. These mutations also disrupt the ability of PGC-1 to co-localize and associate with RNA processing factors. PGC-1 can alter the processing of an mRNA, but only when it is loaded onto the promoter of the gene. These data demonstrate the coordinated regulation of RNA transcription and processing through PGC-1.

Beta-globin gene cluster haplotypes in two North American indigenous populations.

Haplotypes derived from five polymorphic restriction sites were determined in 50 Carrier-Sekani and 70 Mvskoke chromosomes, and the results were integrated with those previously obtained for 11 South American Indian populations. Eleven haplotypes were identified in the Mvskokes, while five were observed in the Carrier-Sekani. As in South American natives, haplotype 2 (+----) and 6 (-++ -+) were the most prevalent among the Mvskoke (46% and 30%, respectively). In the Carrier-Sekani, haplotype 2 was also the most common, but haplotype 5 (-+ -++) was somewhat more frequent (18%) than 6 (12%). High heterozygosities, as well as genetic differentiation, were observed among these two North American and two other South American groups (Mapuche and Xavante). They could be due to non-Indian admixture in the Mvskoke and Mapuche, but the findings in the other two populations require some other type of explanation.

Six-month treatment of obesity with sibutramine 15 mg; a double-blind, placebo-controlled monocenter clinical trial in a Hispanic population.

OBJECTIVE: To evaluate the safety and efficacy of sibutramine 15 mg by mouth once per day in obese patients over a period of 6 months. RESEARCH METHODS AND PROCEDURES: A monocenter, double-blind, placebo controlled, parallel, prospective clinical trial was carried out. Sixty-nine male and female obese patients (body mass index [BMI] > 30 kg/m2) aged 16 to 65 years entered the trial. RESULTS: 22 of 35 patients in the sibutramine group and 9 of 34 patients in the placebo group completed the trial. The high dropout rate in the sibutramine group was due to adverse events in 3 cases, lack of efficacy (as judged by patients) in 7, loss to follow-up in 2, and an orthopedic device being worn in 1; in the placebo group the dropouts were ascribed to lack of efficacy (as judged by patients) in 17 cases and to loss to follow-up in 8 cases. Using the method of last observation carried forward, the weight loss in the sibutramine group was 10.27 kg (95% confidence intervals [95% CI] 7.66; 13.07) and 1.26 kg (95% CI 0.3; 2.23) in the placebo group. The BMI loss was 4.17 kg/m2 (95% CI 3.11; 5.22) in the sibutramine group and 0.53 kg/m2 (95% CI 0.13; 0.92) in the placebo group. The waist circumference reduction was 12.51 cm (95% CI 9.25; 15.77) in the sibutramine group and 3.26 cm (95% CI 1.38; 5.14) in the control group (p<0.05 by paired Student's t test for all the intragroup comparisons). Twenty-three sibutramine patients had 34 adverse events, the most frequent adverse events in the sibutramine group were upper respiratory tract infections (n = 6) and constipation (n = 6); 16 placebo patients had 21 adverse events. Three sibutramine patients withdrew their informed consent when they had adverse events. DISCUSSION: The results show that sibutramine induces significant loss of body weight and waist circumference. Cardiovascular function was not significantly affected by sibutramine. Sibutramine was well tolerated by most of the patients.

Beta2-adrenergic receptor allele frequencies in the Quechua, a high altitude native population.

The beta2-adrenergic receptor is involved in the control of numerous physiological processes and, as the primary catecholamine receptor in the lungs, is of particular importance in the regulation of pulmonary function. There are several polymorphic loci in the beta2-adrenergic receptor gene that have alleles that alter receptor function, including two (A/G46, G/C79) that increase agonist sensitivity. As such a phenotype may increase vaso and bronchial dilation, thereby facilitating air and blood flow through the lungs, we hypothesized that selection may have favoured these alleles in high altitude populations as part of an adaptive strategy to deal with the hypoxic conditions characteristic of such environments. We tested this hypothesis by determining the allele frequencies for these two polymorphisms, as well one additional missense mutation (C/T491) and two silent mutations (G/A252 and C/A523) in 63 Quechua speaking natives from communities located between 3200 and 4200 m on the Peruvian altiplano. These frequencies were compared with those of two lowland populations, one native American (Na-Dene from the west coast of Canada) and one Caucasian of Western European descent. The Quechua manifest many of the pulmonary characteristics of high altitude populations and differences in allele frequencies between the Quechua and lowlanders could be indicative of a selective advantage conferred by certain genotypes in high altitude environments. Allele frequencies varied between populations at some loci and patterns of linkage disequilibrium differed between the old-world and new-world samples; however, as these populations are not closely related, significant variation would be expected due to stochastic effects alone. Neither of the alleles associated with increased receptor sensitivity (A46, G79) was significantly over-represented in the Quechua compared with either lowland group. The Quechua were monomorphic for the C allele at base 79. This variant has been associated with body mass index; however no clearly defined metabolic phenotype has been established. In addition, we sequenced the coding region of the gene in three unrelated Quechua to determine if there were any other polymorphisms common in this population. None were detected.

The switch from early to late transcription in phage GA-1: characterization of the regulatory protein p4G.

The transcription program of the Bacillus phage GA-1, a distant relative of phage Phi29, has been studied. Transcription of the GA-1 genome occurred in two stages, early and late. Early genes were expressed from two promoters equivalent to the Phi29 A2b and A2c promoters, whereas late transcription started at a site equivalent to the Phi29 late A3 promoter. The activity of the GA-1 early A2b and A2c promoters diminished 10 minutes after infection, a time at which expression of the late promoter increased significantly. The switch from early to late transcription required protein synthesis, suggesting the need for viral protein(s). An open reading frame was found in the GA-1 genome coding for a protein showing a 53 % similarity to Phi29 regulatory protein p4, and was named p4G. In Phi29, protein p4 represses the early A2b and A2c promoters and activates the late A3 promoter by recruiting RNA polymerase to it. A binding site for protein p4Gwas localized upstream from the GA-1 late A3 promoter, overlapping with the early A2b promoter. In vitro, protein p4Gprevented the binding of RNA polymerase to the GA-1 early A2b promoter but, unlike in Phi29, had no effect on the expression of the late A3 promoter: RNA polymerase could efficiently bind and initiate transcription from the A3 promoter in the absence of protein p4G. Therefore, activation of late transcription occurs differently in GA-1 and Phi29. We propose that protein p4Gis an anti-repressor which inhibits the binding to the late promoter of an unknown repressor factor present in the host strain.