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Biomedical subjects

T R Turner

Publications and source records attributed to T R Turner.

At least 19 recordsLinked to original sources
PubMed1997

Growth, development, and sexual dimorphism in vervet monkeys (Cercopithecus aethiops) at four sites in Kenya.

Body weight and ten body segment measurements were collected from 367 wild-trapped vervet monkeys (Cercopithecus aethiops) in central and southern Kenya. The animals represent between 70 and 95% of the animals in each of 30 troops at four geographical locations separated by 80 to 380 km. The capture sites differed in altitude, mean annual rainfall and temperature. Two questions are addressed: (1) what are the differences in male and female growth patterns, and (2) what is the relationship between size, climate, and availability of food? Each animal was assigned to an age class based on dental examination. Means for all variables do not diverge for males and females from birth to age class 4 (15-18 months). After this, male and female growth rates diverge. This sexual dimorphism in growth pattern may reflect timing of entry into the reproductive community. A nested analysis of variance (ANOVA) was employed to compare sites, groups within sites and individuals within groups. Statistically significant differences between sites in body weight and body segment measurements are found for adult females. Except for tail length, these differences do not follow Bergmann's or Allen's Rules correlating size differences and temperature, but rather may reflect proximity to cultivated areas or tourist lodges with greater access to human food.

Age Determination by Teeth↗
PubMed1997

Brief communication: the 1996 American Association of Physical Anthropology membership survey.

The 1996 AAPA membership survey included 1,033 participants. This number represents 72.6% of the membership of the association. Data were collected on gender, academic rank, highest degree, decade highest degree was awarded, discipline, employment, and rank order of subdiscipline. There are statistically significant differences (Chi-square test, P < 0.05) in subdiscipline membership including, among others, human and primate evolution, primatology, and skeletal biology. There are also gender differences in number of students and academic rank.

Adult↗
PubMed1996

SIVagm incidence over two decades in a natural population of Ethiopian grivet monkeys (Cercopithecus aethiops aethiops).

The incidence of SIVagm seropositivity in a natural population of Ethiopian grivet monkeys (Cercopithecus aethiops aethiops) is investigated using plasma samples collected in 1973, and shown to be similar to that reported from the same population in 1990-91. Results tend to support our previous conclusions: endemic SIVagm has little or no impact on the survival of wild grivet monkeys, and the virus is transmitted almost always by sexual contact, occasionally by trauma, and rarely if ever maternally. Small differences between 1973 and 1990-93 suggest that the stress of drought years may raise the incidence of traumatic transmission, and temporarily depress transmission by sexual activity, in this population.

Animals↗
PubMed1996

Dietary fiber and laxation in postop orthopedic patients.

The addition of wheat fiber in the diet of post-surgical orthopedic patients as a means of preventing constipation was studied using a quasi-experimental design. It was hypothesized that a 20 gm supplement of All Bran and natural bran would promote spontaneous bowel movements, reduce the incidence of constipation, and thus decrease the need for elimination interventions. The results show that the study group had more spontaneous bowel movements and required fewer elimination interventions than did the control group.

Adult↗
PubMed1993

Statistical discriminant analysis of arrhythmias using intracardial electrograms.

The problem of classifying ventricular arrhythmias from intracardial electrograms is considered. Standard statistical discrimination procedures are applied using a simple parametric model for the shape of the pulse near its peak. This approach makes simultaneous use of the model parameters, has well known statistical properties, and involves computations that can be carried out efficiently. Preliminary analyses of real data sets, using both linear and quadratic discrimination functions, yield promising results.

Algorithms↗
PubMed1989

Development of a human cell line by selection and drug-metabolizing gene transfection with increased capacity to activate promutagens.

We have isolated a human lymphoblastoid cell line with higher levels of native cytochrome P450IA1 activity and by DNA transfection introduced human cDNAs for a putative cytochrome P450IIA2 and epoxide hydrolase (E.C. 3.3.2.3). The resultant cell line, designated MCL-1, was substantially more sensitive to the mutagenicity of dimethylnitrosamine and benzo[a]pyrene than the AHH-1 cell line and was found to have increased metabolism of benzo[a]pyrene to dihydrodiols. The increase in native cytochrome P450IA1 activity was achieved by mutation and selection based on resistance to the phototoxicity of benzo[ghi]perylene. One resistant clone, designated L3, was used for subsequent studies. Two complete cDNAs, one encoding a putative cytochrome P450IIA2 and the other a microsomal epoxide hydrolase, were isolated from a human liver cDNA library. After introduction of the cDNAs into an expression vector and transfection into AHH-1 cells, gene expression was detected at the level of enzyme activity (epoxide hydrolase) or by increased sensitivity to dimethylnitrosamine cytotoxicity/mutagenicity (putative P450IIA2). A vector containing both cDNAs was then constructed and transfected into L3 cells to produce MCL-1 cells. The potential usefulness of drug-metabolizing gene transfection and of the MCL-1 cell line, in particular, for genetic toxicity testing is discussed.

Benzo(a)pyrene↗
PubMed1986

STLV-I antibodies in feral populations of East African vervet monkeys (Cercopithecus aethiops).

Serum samples from feral populations of African green monkeys (Cercopithecus aethiops) were screened for antibodies to the simian T-lymphotropic virus, type I (STLV-I). Blood samples had been collected from 336 monkeys in 4 regions of central and southern Kenya in 1978 and 1979, from 114 monkeys in central Ethiopia in 1973, and from 85 monkeys from the Kampala region of Uganda in 1966. A total of 178/535 monkeys (33%) were seropositive (STLV-I+). Only 4/114 monkeys (4%) from Ethiopia were seropositive compared to 25/85 Ugandan monkeys (29%) and 149/336 Kenyan monkeys (44%). Epidemiological analysis of the Kenyan monkeys showed that 37% of the males and 54% of the females were STLV-I+, and that there was a progressive increase in the proportion of STLV-I+ monkeys of both sexes with age, rising from an average of 16% in infants (less than 9 months) to an average of 69% in adults (greater than 42 months). The proportion of STLV-I+ monkeys was higher among females in each age category. Seropositivity for antibodies to STLV-I had no apparent effect on the health of monkeys, and no association with the occurrence of Hepatocystis parasitemia was seen in this species. The analysis of data from infants of STLV-I+ mothers showed that seroconversion had occurred in 1 of 3 cases, suggesting that vertical transmission of the STLV-I virus is not an inevitable consequence for infants of seropositive mothers.

Age Factors↗
PubMed1985

Mutagenicity of 1,2-dichloroethane and 1,2-dibromoethane in two human lymphoblastoid cell lines.

1,2-Dichloroethane (DCE) and 1,2-dibromoethane (DBE) were tested for the ability to induce gene mutations in two human lymphoblastoid cell lines, designated AHH-1 and TK6. Both chemicals were 'direct-acting' mutagens in both cell lines. DBE was essentially equally mutagenic in TK6 cells and AHH-1 cells. In contrast, DCE was 25-fold more mutagenic in the AHH-1 cell line than in the TK6 cell line. This differential sensitivity between AHH-1 cells and TK6 cells was related to the levels of glutathione S-transferase activity in these two cell lines.

Cell Line↗
PubMed1985

Reflux esophagitis.

Explore the source record for details and available documents.

Esophagitis, Peptic↗
PubMed1984

Thermostability characteristics of glucosephosphate and triosephosphate isomerase in erythrocytes from several species.

Significant differences in the thermostability of both glucosephosphate and triosephosphate isomerase were noted among a series of six primate and five nonprimate species. The enzyme structural differences among species, as assessed by thermostability profiling, was greater than expected from electrophoretic mobility patterns. Microheterogeneity of GPI, i.e. differences in thermostability within a species that are not detectable by electrophoresis, was detected in two primate species. Major differences in the levels of erythrocyte enzyme activity were observed with human and cow differing by 18-fold for TPI and baboon and cow differing by seven-fold in GPI activity.

Animals↗
PubMed1984

Variation in erythrocyte enzyme activity among primate species.

Significant differences between species in the mean level of enzyme activity, ranging from 50 to 400%, were detected during a study of 10 enzymes from erythrocytes of humans and five non-human primates. The activity differences were consistent with variation, between species, at the structural loci for specific enzymes rather than differences in mean cell age, hemoglobin content or other pleiotropic effects. For seven of the eight loci at which direct comparisons among the six species could be made, the number of species-specific activity differences was greater than the number of variants observed by electrophoresis. Thus not only do activity measurements detect previously "hidden" variation among species but they also provide information regarding genetic differences which may be of potential physiological and/or selective relevance.

Animals↗
PubMed1983

Patterns of genetic variability in the serum proteins of the Kenyan vervet monkey (Cercopithecus aethiops).

An electrophoretic survey of 13 serum proteins was carried out on samples drawn from 340 vervet monkeys (Cercopithecus aethiops) living in 30 troops from four different localities in central and southern Kenya. The proportion of polymorphic loci is 0.17 and the average heterozygosity is 0.05. The group specific component, prealbumin carboxylesterase, and transferrin are all polymorphic. The analysis of the patterns of gene diversity show that a large part of the genic variation exists within individual troops and among neighboring troops from the same trapping locality. Only a small proportion of the overall genetic variability occurs between the populations at the different trapping localities which are separated by between 80 and 380 km. The migration of young males from their natal troops is a likely mechanism of gene flow among the vervet populations. Gene flow appears to be sufficient to prevent high levels of geographic variation in the gene frequencies at these loci, but is insufficient to prevent the occasional fixation of alleles in some local populations.

Alkaline Phosphatase↗
PubMed1981

Blood protein variation in a population of Ethiopian vervet monkeys (Cercopithecus aethiops aethiops).

Seven small groups of vervet monkeys (Cercopithecus aethiops aethiops), totaling 124 individuals, from Awash National Park, Ethiopia, were trapped and blood samples were obtained. Twenty-three loci were examined by starch gel electrophoresis and four loci, Tf, E, ADA, and PMG2 were found to be polymorphic. The average heterozygosity (H) of the population was calculated to be 5.6%. No significant deviations from Hardy-Weinberg equilibrium proportions occurred and a chi-square test for group homogeneity was also not significant. Average Fst for all polymorphic loci was calculated to be 0.062. This suggests that the entire group functions as a single Mendelian population.

Animals↗
PubMedDate not supplied

A metabolically competent human cell line expressing five cDNAs encoding procarcinogen-activating enzymes: application to mutagenicity testing.

A human B-lymphoblastoid cell line, designated MCL-5, constitutively expressing human cytochrome P-450 CYP1A1 and also expressing five transfected human cDNAs encoding drug-metabolizing enzymes, has been developed. cDNAs encoding CYP1A2, CYP2A6, and microsomal epoxide hydrolase (mEH) were introduced by using a vector conferring hygromycin B resistance, and cDNAs encoding CYP2E1 and CYP3A4 were introduced by using a vector conferring resistance to 1-histidinol. MCL-5 cells stably expressed all five cDNAs and the native CYP1A1 as determined by measurement of form-specific enzyme activity levels. The mutagenicity of seven model procarcinogens to MCL-5 cells was examined at the hypoxanthine guanine phosphoribosyltransferase (hprt) and thymidine kinase (tk) loci. Exposure to benzo[a]pyrene (BP), 3-methylcholanthrene (3MC), N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), aflatoxin B1, (AFB1), 2-(acetylamino)fluorene (AAF), or benzidine (BZD) induced a statistically significant increase in mutant frequency. Linear interpolation of the concentration of procarcinogen necessary to produce a doubling of the mutant fraction at the hprt locus in MCL-5 cells and the parent AHH-1 cell line revealed that, for each of the chemicals examined, except BZD, MCL-5 cells were significantly more sensitive than the parent AHH-1 cells. The increase in sensitivity to mutagenicity ranged from 3-fold for AAF to greater than 40,000-fold for NDMA. MCL-5 cells have great potential as a screening system for the analysis of human procarcinogen/promutagen activation.

Carcinogenicity Tests↗