Sara A. Barton

Colorado Center for Reproductive Medicine

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William J. Schull

The University of Texas Health Science Center at Houston

Ranajit Chakraborty

UNSW Sydney

Craig L. Hanis

The University of Texas Health Science Center at Houston

Francisco Rothhammer

University of Tarapacá

Ricardo M. Cerda‐Flores

Universidad Autónoma de Nuevo León

Hernán Palomino

Universidad Andrés Bello

J. Clench

The University of Texas Health Science Center at Houston

R E Ferrell

University College London

William H. Mueller

Institute of Occupational Medicine

David Hewett‐Emmett

The University of Texas Health Science Center at Houston

Cooperative Institutions

The University of Texas Health Science Center at Houston

University of Chile

The University of Texas at Austin

Mexican Social Security Institute

New York University

Yunnan University

University of Tarapacá

Harvard University

Fred Hutch Cancer Center

University of Michigan–Ann Arbor

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HLA‐DQB1, ‐DQA1, ‐DRB1 linkage disequilibrium and haplotype diversity in a Mestizo population from Guadalajara, Mexico

Tissue Antigens (2004)

L.M. Cortes L.M. Baltazar Francisco J. Perea Martha Patricia Gallegos‐Arreola Shahida Flores

Abstract: HLA‐DQB1, ‐DQA1, and ‐DRB1 genes were typed by polymerase chain reaction with sequence‐specific primer (PCR‐SSP) in 159 healthy volunteers from 32 families living in Guadalajara, Mexico. Three‐locus genotype data from all family members were used to infer haplotypes in 54 unrelated individuals of the sample, from which estimate of segregating haplotype frequencies and linkage disequilibrium (LD) between loci were computed. Genotype distributions were concordant with Hardy–Weinberg expectations (HWE) for all three loci, and allele distributions were similar to the ones observed in other Latin‐American populations. Of the 56 distinct three‐site (DQB1‐DQA1‐DRB1) haplotypes observed in the sample, the five most common (i.e., with frequencies of five counts or more) were: *0302‐*0301‐*04, *0201‐*0201‐*07, *0301‐*0501‐*14, *0402‐*0401‐*08, and *0501‐*0101‐*01. These common three‐locus haplotypes also contributed to the majority of the significant two‐locus linkage disequilibria of these three sites.

Linkage Disequilibrium

10.1111/j.0001-2815.2004.00202.x

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Citations (9)

Panel discussion

International Journal of STD & AIDS (2009)

Sara A. Barton M Fisher Katharina Mayer

Panel discussion

10.1258/ijsa.2008.08s203

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Genetic components of variations of red cell glycolytic intermediates at two altitudes among the South American Aymara

Annals of Human Biology (1983)

Ranajit Chakraborty J. Clench R E Ferrell Sara A. Barton William J. Schull

SummaryRed cell haemoglobin (Hb), haematocrit (Ht), 2,3-diphosphoglycerate (DPG), and adenosine triphosphate (ATP) levels were measured in 876 individuals from six villages at two altitude levels (altiplano and coast) of the Departmento de Arica of Northern Chile. Of these, data on 761 individuals are subjected to analysis to search for the evidence of genetic adaptation to a hypoxic environment at a high altitude. Total phenotypic variance for each of the variables is higher at the altiplano as compared to their counterparts at the coastal level. Data on 1127 pairs of relatives of six degrees of relationships are used to determine the genetic component of variation in each of these four traits. To a certain extent the larger familial correlations as well as higher variances at altiplano are explained by the apparent assortative mating (which may again be due to their restricted population size) at the higher elevation. Yet, at least in three variables (Hb, Ht, and DPG) no reduction in the additive genetic component of variation is noticed at the higher altitude. ATP seems to have the highest degree of genetic component of variance, particularly at the coastal level. Some implications of these results are discussed in the light of their roles in the glycolytic pathway.

Assortative mating

10.1080/03014468300006311

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Citations (12)

Evaluation of the POCkit? HSV2 serology test at point-of-care

Journal of the European Academy of Dermatology and Venereology (1998)

Sara A. Barton

There were 50 patients with acute epididymitis who were evaluated prospectively by history, examination and microbiologic studies, including cultures for aerobes, anaerobes, Neisseria gonorrhoeae, Chlamydia trachomatis and Ureaplasma urealyticum. Escherichia coli was the predominant pathogen isolated from the urine of men more than 35 years old, while Chlamydia trachomatis and Neisseria gonorrhoeae were the predominant pathogens isolated from the urethra of men less than 35 years old. The etiologic role of Escherichia coli and Chlamydia trachomatis was confirmed by isolation from epididymal aspirates from a high proportion of men with positive urine or urethral cultures for these agents. Chlamydia trachomatis epididymitis accounted for two-thirds of idiopathic epididymitis in young men and often was associated with oligospermia. Of 9 female sexual partners of men with Chlamydia trachomatis infection 6 had antibody to Chlamydia trachomatis, of whom 2 had positive cervical cultures for this organism and 2 others had non-gonococcal pelvic inflammatory disease. Antibiotic therapy with tetracycline was effective for the treatment of men with Chlamydia trachomatis epididymitis and should be offered to the female sex partners

Neisseria gonorrhoeae

Epididymitis

Mycoplasma genitalium

Ureaplasma urealyticum

Ureaplasma

10.1016/s0926-9959(98)95032-2

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2,3-Diphosphoglycerate and night vision.

PubMed (1981)

W.J. Schull Rainer Goldsmith J. Clench R. E. Ferrell Sara A. Barton

Recovery of night vision at altitude has been examined in relationship to changes of 2,3,diphosphoglycerate (DPG). It appears that, if DPG influences night adaptation, its effect is small. Inter-individual variability is large, both in terms of DPG and performance on the MESOP, the device used to measure dark adaptation.

Diphosphoglycerate

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Citations (3)

Penile ulceration with foscarnet therapy

AIDS (1993)

Graeme Moyle Sara A. Barton Brian Gazzard

Foscarnet

Penile Diseases

10.1097/00002030-199301000-00031

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Citations (18)

The Aymara of Western Bolivia: health and disease.

PubMed (1980)

F. Murillo Sara A. Barton H Palomino Lenart Schull Wj

The world medical community has long been interested in altitude-related disease and disability among residents of high Andes towns and villages. Nevertheless, with few exceptions, data on this subject have been rather limited. To help fill the gap, a number of academic and government institutions in Bolivia, Chile, Ecuador, Peru, and the United States have been collaborating on a broad research effort known as the Multinational Andean Genetic and Health Program. This article reports the results of one part of that program-involving examination of 429 people living in two highland communities of western Bolivia.

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Citations (4)

[Genetic composition of Chilean population: the Pehuenches from Trapa-Trapa].

PubMed (1993)

Elena Llop Z Harb M. Acuña R Moreno Sara A. Barton

This study describes the genetic composition of Pehuenche indians from Trapa-Trapa. The admixture analysis revealed that this group has conserved most of its pre-Columbian gene pool and therefore, is representative of the indians that lived in Southern Chile before the Spanish conquest. A relatively high frequency of a esterase D variant seems to indicate that this is a Chilean aboriginal population marker. The Chilean Pehuenches are genetically similar to their Argentinean relatives, which is not surprising since this last group crossed the Andes Mountains in historic times.

CONQUEST

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Drilling Cost Reduction Through Use of Torque Controlling Features on Steerable Drill Bits Within Latin America

Latin American and Caribbean Petroleum Engineering Conference (2009)

Sara A. Barton Alexis Garcia P. Pogliano Ana Catarina Silva M. Pelligra

Abstract Toolface Control is widely regarded as one of the greatest challenges when drilling directionally with a Fixed Cutter (FC) drill bit on a Steerable Motor assembly. Toolface offset is proportional to the torque generated by the bit, and by nature, FC bits generate high levels of torque. If large changes in downhole torque are produced while drilling, this will cause rotation of the drill string, and loss of toolface orientation. This results in inefficient drilling and increases risk of bit and downhole tool damage. This paper examines the effect of varied components of a FC drill bit to determine the key design requirements to deliver a smooth torque response and improved directional performance. This includes review of the results from comprehensive laboratory testing to determine the effectiveness of a number of varied, removable Torque Controlling Components (TCC). These, in combination with specific cutting structure layouts, combine to provide predictable torque response while optimized for high rates of penetration. In addition, unique gauge geometry is disclosed that was engineered to reduce drag and deliver improved borehole quality. This gauge design produces less torque when sliding and beneficial gauge pad interaction with the borehole when in rotating mode. Field performance studies from within Latin America clearly demonstrate that matching TCC, an optimized cutting structure, and gauge geometry to a steerable assembly delivers smooth torque response and improved directional control. Benefits with regard to improved stability are also discussed. Successful application has resulted in significant time and cost savings to the operator, demonstrating that Stability and Steerability does not have to result in loss of penetration rate.

Drill bit

Directional Drilling

Drill string

10.2118/121853-ms

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Citations (5)

Circadian heart rate rhythmicity in natives living at high altitude.

PubMed (1980)

J. Clench Sara A. Barton Lenart F. Murillo Schull Wj

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Citations (1)