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T Jenkins

Publications and source records attributed to T Jenkins.

At least 163 records · Page 9Linked to original sources
PubMed1987

Fanconi anemia: another disease of unusually high prevalence in the Afrikaans population of South Africa.

We have investigated the prevalence of homozygous and heterozygous Fanconi anemia (FA) in the Afrikaans community of the southern Transvaal Province. The minimum birth incidence of FA in white, Afrikaans-speaking South Africans was estimated to be 1 in 22,000, with the calculated heterozygote prevalence being approximately 1 in 77. Alternatively, based on a point prevalence of 1 in 26,000, the carrier rate may be estimated as 1 in 83. It is postulated that this unusually high frequency of the gene for FA is attributable to founder effect.

Abnormalities, Multiple↗
PubMed1987

The HLA linked iron loading gene in an Afrikaner population.

The serum ferritin concentration was used as a screening test to identify the presence of iron overload in 599 Afrikaans subjects (300 males and 299 females) living in the South Western Cape, South Africa. Seventeen of the males with concentrations greater than 400 micrograms/l were reevaluated three and five years later. Serum ferritin concentrations were measured again and further diagnostic procedures were carried out. These included an assessment of alcohol intake and measurements of serum gamma glutamyltransferase, the percentage saturation of transferrin, and HLA-A,-B,-C, and -DR loci typing on the subjects as well as their families. Liver biopsies were performed on some affected subjects. Of the original 16 index subjects, four were diagnosed as homozygous for the HLA linked iron loading gene which is responsible for the clinical disease idiopathic haemochromatosis. Six appeared to be heterozygotes, three were heterozygotes who were also abusing alcohol, and two did not fit into any of the diagnostic groups. The calculated gene frequency was 0.082, with an expected heterozygote frequency of 0.148. The fact that no females were identified in the study suggested that the diagnostic criteria for homozygosity (serum ferritin greater than 400 micrograms/l and % saturation greater than 60%) were set too high. The data were therefore recalculated for the 300 males; when this was done the gene frequency was 0.115 and the heterozygote frequency 0.024. Two subjects were diagnosed as homozygotes in the study of family members and 37 as heterozygotes (33 definite and four probable). Both the homozygotes and nine of the heterozygotes showed mild to moderate disturbances of iron metabolism. There was considerable overlap between the phenotype expression in these nine heterozygotes and the homozygotes, probably as a result of setting the threshold for the serum ferritin concentrations at the relatively high value of 400 microgram/ml. By doing this a small subset of heterozygotes with biochemical abnormalities was identified. The results of the present pilot study suggest a high frequency of the HLA linked iron loading gene in the Afrikaner population of South Western Cape.

Adolescent↗
PubMed1987

Carcass composition and adipose tissue metabolism in growing sheep.

Experiments were conducted to investigate biological variables that influence fat accretion in growing ram lambs. Carcass composition and adipose tissue development were measured in Columbia-sired ram lambs from 32.0 to 73.9 kg body weight. Five or six ram lambs were slaughtered every 2 mo, from 4 to 10 mo of age. The percentage of carcass fat-free dry matter decreased with age from 30.9 to 27.5% (P less than .05), while the percentage of carcass fat increased from 17.7 to 33.4%. Similarly, offal fat-free dry matter decreased with age (from 24.5 to 21.5), and there was nearly a threefold increase in the percentage of offal fat (P less than .05 for both measures). Subcutaneous adipocyte diameter and lipogenesis in vitro increased from 4 to 6 mo of age, and did not increase further with age. A bimodal distribution of adipocytes was apparent in the 4-mo-old lambs, but was not observed in any other age group. The presence of glucose in incubation media stimulated acetate incorporation into fatty acids in vitro in adipose tissue from 8- and 10-mo-old lambs. However, glucose did not affect the rate of lipogenesis from lactate. The data indicate early, rapid increases in carcass fat accretion, which corresponded to similar increases in lipogenesis and lipogenic enzyme activities.

Adipose Tissue↗
PubMed1987

Globin gene-associated restriction-fragment-length polymorphisms in southern African peoples.

The combination of polymorphic restriction-enzyme sites in the 3' region of the beta-globin gene cluster shows very little variation in southern-African Bantu-speaking black and Kalahari !Kung San populations. The sites of the 5' region, on the other hand, show marked variation, and two common haplotypes are present--the "Negro" type (- - - - +) and the "San" type (- + - - +)--in frequencies of .404 and .106, respectively, in the Bantu-speakers and .262 and .405, respectively, in the San. Twenty of 23 beta s-associated haplotypes in southern-African Bantu-speaking black subjects were the same as that found commonly in the Central African Republic (CAR)--i.e., the "Bantu" type--a finding providing the first convincing biological evidence for the common ancestry of geographically widely separated speakers of languages belonging to the Bantu family. The (-alpha) haplotype has a frequency of .21 in the Venda, .07 in both the Sotho-Tswana and the Nguni, and .06 among the !Kung San. These data are interpreted in the light of Plasmodium falciparum malaria selection and population movements in the African subcontinent.

Africa, Southern↗
PubMed1987

Sero-genetic studies on the Ambo of Namibia.

The Ambo are the largest population group of Namibia/South West Africa and consist of seven geographical and sociopolitical entities speaking different dialects of a common language. Nearly 600 individuals representing all the dialect groups were tested for 23 sero-genetic systems: the results reveal no evidence of significant San admixture and unusual alleles suggest an affinity with the Herero which confirms oral traditions of a common origin. Genetic distance measurements indicate that the Dama may also have a connection with these peoples and it is probable that most of the Bantu-speaking Negroes of Namibia/South West Africa come from the same stock.

Black People↗
PubMed1987

Thiamin status and biochemical indices of malnutrition and alcoholism in settled communities of !Kung San.

Thiamin status and biochemical indices of malnutrition and alcoholism have been studied in groups of settled !Kung San living in the northern Kalahari Desert of Namibia. One third of the men and 20% of the women had low red cell thiamin concentrations. Raised serum gamma glutamyl transferase (gamma GT) activities were present in 30% of the men and 11% of the women. gamma GT activities were negatively correlated with red cell thiamin concentrations (r = -0.321, P less than 0.01). Raised mean corpuscular volumes were observed in over half the subjects. Anaemia was rare. Plasma protein and albumin concentrations were satisfactory. Cholesterol concentrations were relatively low (mean 4.1 mmol 1-1). The present results identify a high prevalence of thiamin deficiency in settled !Kung San, and suggest that alcohol abuse is the main contributory factor.

Adult↗
PubMed1987

The effect on fixation disparity and associated heterophoria of reading at an abnormally close distance.

It is well established that prism stress on binocular vision produces fixation disparity. It is therefore suggested that fixation disparity is a sign of stress on binocular vision. The authors have previously looked at the stress caused by reading in reduced levels of illumination, and found that the average fixation disparity and associated heterophoria become more exophoric. In this paper the effect on fixation disparity and associated heterophoria of reading at an abnormally close distance is reported. It was found that in 50 young adults fixation disparity and associated heterophoria increased to a greater degree of exo-disparity. An analysis of the visual symptoms indicated that there was also an increase in the visual discomfort and other symptoms.

Adult↗
PubMed1987

The clinical assessment of binocular vision before and after a working day.

This paper looks at the clinical investigative and measurement procedures used in assessing binocular vision at the beginning of a normal working day and compared with the same procedures carried out in the afternoon which included several hours of close work. In 84 young adults, it was found that dissociated heterophoria, associated heterophoria and fixation disparity increased. This was accompanied by visual symptoms. It is likely that any decompensation of heterophoria is worse at the end of a working day. The results of this investigation raise the question of the value of some clinical tests for binocular assessment carried out at the beginning of the day.

Adolescent↗
PubMed1986

Occurrence of two distinct succinate thiokinases in animal tissues.

Although succinate thiokinase from mammalian sources has hitherto been described as showing substrate specificity for guanine nucleotide, a range of mammalian tissues has here been found to display succinate thiokinase activity with both guanine and adenine nucleotides as substrates. Evidence is presented for the existence of two distinct succinate thiokinases and this is confirmed by their separation by affinity chromatography. Each enzyme is specific for one nucleotide and is inhibited by the non-substrate nucleotide. The physiological roles of the two enzymes is yet to be established.

Adenosine Diphosphate↗
PubMed1986

Inverted Y chromosome polymorphism in the Gujerati Muslim Indian population of South Africa.

An inverted Y chromosome has been found at a very high frequency in a Muslim Indian community living in the Johannesburg-Witwatersrand area of the Transvaal Province of South Africa: 8 of 141 (5.7%) retrospectively identified Indian males had an inv(Y)(p11.2q11.23) and all were of the Muslim faith. The inversion was found in 22 of 72 (30.5%) prospectively studied normal Muslim Indian males. All the carriers of the inversion were Gujarati-speakers whose families migrated to the Transvaal from the Gujerat Province of India during the first half of this century. The origins of the ancestors of the individuals with inv(Y) were traced to a small village, Kholvad, near the city of Surat, and some neighbouring villages. The polymorphic frequency of the inv(Y) has probably been produced through random genetic drift in a reproductively isolated community, maintained by strict endogamous marriage customs based on religious and linguistic affiliations. There was no indication that the inverted Y was associated with any reproductive disadvantages.

Black People↗
PubMed1986

Partial adenosine deaminase deficiency: another family from southern Africa.

Adenosine deaminase (ADA) from a partially ADA-deficient Xhosa man has been characterized. This is only the second such case described in southern Africa, the previous one being a Kalahari San ("Bushman"). Red blood cell ADA levels were found to be only 6-9% of normal whereas his white cell ADA levels were much higher at 30% of normal. The stability of the enzyme at 57 degrees C was shown to be greatly decreased indicating a mutation resulting in an enzyme with decreased stability in vivo. The Michaelis constant (Km) for adenosine was found to be normal. Deoxy-ATP levels in the red cells were elevated 2- to 3-times above normal, although this appears to be of no immunological consequence. Starch gel electrophoresis of red cell ADA from family members of the index case, in conjunction with red cell ADA activity levels, suggested that both parents carried a gene for partial ADA deficiency. Isoelectric focusing studies suggested that the two parental partial ADA-deficiency genes were not the same. Electrophoretic studies also revealed that another rare allele of ADA, possibly ADA*5, was segregating within the same family although this event appears to be unconnected with the ADA partial deficiency. A Xhosa population sample was assayed for red cell ADA activity. The results suggested a frequency of 0.015 +/- 0.010 for ADA partial-deficiency alleles, although the number of different alleles involved is not known.

Adenosine Deaminase↗
PubMed1986

The haematological puzzle of Hb J Cape Town is partly solved.

Molecular studies have shown that the mutation giving rise to Hb J Cape Town (alpha 92 arg----gln) is situated on a chromosome from which the other alpha-globin gene has been deleted. The -alpha 3.7 deletion has resulted from crossing-over within segment I of the Z region of homology. There appears to be an unusually high proportion of the variant haemoglobin in heterozygotes which cannot be explained by gene dosage alone.

Chromosome Deletion↗
PubMed1986

Surface properties of developing stages of Trichuris muris.

Surface properties of developing stages of Trichuris muris were investigated by analysis of binding affinities for specific anti-parasite antibodies present in a range of infection sera; in vitro eosinophil adherence studies; and binding of the fluorescent-labelled lectins, Con A, WGA, PNA and RCA. In general, larvae of any one particular stage did not bind anti-parasite antibodies present in serum collected at an earlier stage of the infection, thus indicating a considerable degree of antigenic stage-specificity. Forty day and older parasites displayed similar binding properties and it is suggested that no major changes in surface antigenicity occur after the final moult at day 25-30 after infection. Surface properties were also examined by means of complement and antibody-mediated eosinophil adherence assays. Attachment of eosinophils was maximal with day 5 larvae, although even at this stage not all of the parasite surface was covered with attached cells. Despite adherence, eosinophils were unable to effect parasite killing, even after 48 h of incubation. These studies showed that eosinophil adherence-promoting antibodies were present in immune sera; that the larval parasite surface was able to activate complement by the alternate pathway with subsequent generation of C3b molecules, and that the parasite was able to withstand eosinophil adherence and secretion by an as yet unidentified evasive stratagem. Studies with fluorescent-labelled lectins showed that all larval stages (days 5-25 after infection) were positive for Con A binding. Early larval stages (days 5-10 after infection) also bound PNA and WGA. Interestingly, recently moulted individuals rarely exhibited fluorescence, but cast cuticles fluoresced brightly.

Animals↗
PubMed1986

A new epsilon globin HincII variant fragment length in a South African Negroid family.

A new HincII epsilon globin variant is reported in a South African Negroid family. The usual HincII epsilon globin fragment lengths are 8.0 and 3.7 kb and the variant described here is 14.0 kb in length. The 14.0 kb fragment was generated by a site alteration removing the 3' HincII site on a chromosome that already lacked the 5' HincII site. It appears that there are differences among races with regard to the frequencies of the 8.0 and 3.7 kb alleles. The 3.7 kb allele is the more common form in Caucasoids whereas the 8.0 kb allele occurs in the majority of Negroid and Khoisan subjects.

Black People↗
PubMed1986

Differentiation of heterozygotes in recessive albinism.

Skin pigmentation was measured by reflectance spectrophotometry in 43 albinos, 44 of their relatives, and 123 random controls among Swazi subjects in southern Africa. Mean reflectance of the subject groups diminishes in the sequence affected subjects, obligate heterozygotes, other unaffected family members, random subjects, and the differences among the unaffected groups are highly significant. A discriminant function fitted to the obligate heterozygotes and random subjects is significant statistically but is not efficient enough to be applied in the diagnosis of the non-carrier state.

Albinism↗
PubMed1986

Alpha-1-antitrypsin variation in Southern Africa.

Eleven Southern African populations were shown to be polymorphic at the alpha 1-antitrypsin locus. A 'new' electrophoretically detectable alpha 1-antitrypsin variant (PiWsan) which has a lower isoelectric point than does PiM, was found in the Bantu-speaking Negro and San populations. PiWsan appears to be functionally normal as judged by quantitative and qualitative studies.

Africa, Southern↗