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Biomedical subjects

J A Hunt

Publications and source records attributed to J A Hunt.

At least 127 records · Page 7Linked to original sources
PubMed1981

Evolutionary distances in Hawaiian Drosophila measured by DNA reassociation.

Comparisons of the sequence divergence of three species of Hawaiian Drosophila have been made by hybridization of single-copy tracer DNA of each of the species with driver DNA from each species, and measurement of the average melting temperature (Tma) in a chaotropic solvent (2.4 M tetraethylammonium chloride) which minimizes differences due to base composition. Correction was made for the length of hybrid duplex regions to obtain the reduction in thermal stability due to divergence. An accuracy of +/- 0.2 degrees C was achieved and the mean reduction in Tm for hybridization between D. heteroneura and D. silvestris (found only on the island of Hawaii) was 0.55 degrees C and between D. picticornis, found only on the island of Kauai, and the other two species was 2.13 degrees C. The rate of DNA change is estimated to be between 0.2 and 0.4%/My by assuming that the D. heteroneura-D. silvestris divergence occurred 0.8 My ago and the divergence between these species and D. picticornis between 4 and 6 My ago. The general single copy DNA sequence divergence appears to be very much greater than the minimal coding region sequence divergence previously estimated from allozyme studies.

Animals↗
PubMed1979

Analysis of the ratio of alpha- to beta-globin and globin messenger ribonucleic acid content of fractionated rabbit erythroid bone-marrow cells.

The ratio of alpha- to beta-globin mRNA was measured by hybridization of a constant amount of highly purified alpha- or beta-globin cDNA (complementary DNA) with increasing amounts of RNA in the range up to 20% cDNA hybridization, where an essentially linear reaction is obtained. Statistical analysis indicates that the ratio of alpha- to beta-globin can be measured within a maximal error of +/- 0.3 and in most cases is better than +/- 0.15. Under these conditions there is no significant deviation from the ratio of 1.3 in the alpha- to beta-globin mRNA ratio of RNA isolated from erythroid cells rich in pronormoblasts through to reticulocytes. If the ratio of alpha- to beta-globin mRNA exceeded 1.7 or was less than 0.9 in pronormoblasts, it would be detected in these experiments. The overall globin mRNA content increases to a maximal value in the fractions rich in basophilic normoblasts of 30,000--50,000 molecules/cell. However, the accuracy of these determinations is not as great as for the ratio determinations, and no significant deviations were seen except in the cells rich in pronormoblasts, which contained less globin mRNA than the later stages.

Animals↗
PubMed1979

Transplacental passage of islet cell antibody in infants of diabetic mothers.

The incidence of pancreatic islet cell antibody (ICAb) was assessed in the cord blood and sera of infants of diabetic mothers (IDM). ICAb activity was detected in the cord blood of 10 of 36 (27.8%) consecutive IDM studied and in 0 of 111 (0%) cord bloods of normal control infants. In all instances, ICAb activity in the cord sera was of the immunoglobulin (IgG) class and was associated with ICAb in maternal sera at the time of delivery. No correlation was observed between the incidence of ICAb in IDM and alterations in fetal growth parameters, congenital malformation rates, cord blood insulin levels, or the incidence of neonatal complications. The evidence would support transplacental passage of ICAb from diabetic mothers to their offspring, but would not support a primary pathogenetic role for ICAb in the clinical or metabolic alterations observed in these infants.

Antibody Formation↗
PubMed1978

A specific dimerization of rabbit beta-globin messenger ribonucleic acid.

Rabbit globin mRNA, when layered in low salt on 0.1 M-NaCl/sucrose gradients, separates into two peaks of material. Translation of these two RNA fractions in the wheat-germ cell-free system, hybridization against globin complementary DNA (cDNA) and cross-hybridization against cDNA species prepared from each fraction show that the first peak sedimenting at 10S is a alpha-globin mRNA and the second peak, sedimenting at approx. 15S, is beta-globin mRNA. The sedimentation rate of the beta-globin mRNA is concentration-dependent. By changing concentration and pH, it is indicated that in low-salt beta-globin mRNA adopts a conformation that leads to specific, but weak, self-dimerization during centrifugation in 0.1M-NaCl. This property permits rapid preparation of intact and relatively pure alpha- and beta-globin mRNA species.

Animals↗
PubMed1978

The radiological features of alcoholic ulcero-osteolytic neuropathy in Blacks.

The radiological features in the bones and the angiographic changes in the vessels of the lower limbs of 15 chronic alcoholic men are discussed. The distal arteries demonstrate the features of neovascularization. Infective and resorptive changes in the bones of the forefeet are described. These features are related to chronic infection or to the toxic effects of the alcohol.

Adult↗
PubMed1977

Emergence of diverticular disease in the urban South African black.

A low residue, fiber-deficient diet has been postulated as the cause of diverticular disease--the commonest affliction of the colon in the Western nations. This condition is virtually unknown in Africans (blacks) who live south of the Sahara, and who have not changed their traditional high residue diet. This paper presents 16 Africans with diverticular disease. A disturbing feature is that 5 of the patients are young, being in their fourth decade, and only 4 are over the age of 60. Their dietary history confirms the hypothesis as to the etiology, and also shows that the urbanization of the South African black has been accompanied by the emergence of diverticular disease, a condition higherto virtually nonexistent in this population.

Adult↗
PubMed1977

Ruptured tuboovarian abscess. Is hysterectomy necessary?

The use of conservative pelvic surgery combined with intra- and postoperative antibiotic peritoneal lavage has been evaluated in 113 women with generalized peritonitis due to ruptured tuboovarian abscess. Mortality was 7.1% and hysterectomy was only required in 3% of cases. Hormonal and menstrual functions were retained in 73.5% and the potential for future pregnancy in 42.5%. Further surgery was required in 17.5% of the patients. These results are contrasted with recent series of comparable size in which the mortality and morbidity were similar but the frequency of hysterectomy ranged from 70--100%. It is concluded that hysterectomy is not necessary in the management of ruptured tuboovarian abscess if the major source of sepsis is removed and adequate peritoneal drainage is provided by the use of lavage.

Abscess↗
PubMed1976

Ribonucleic acid synthesis in rabbit erythroid cells.

Kinetic studies on the synthesis of RNA in mature bone-marrow erythroid cells from rabbits were made by measuring the incorporation of [2-3H]adenosine into the ATP pool and RNA over periods up to 8h. By use of equations to fit the pool specific radioactivity and an equation using the same type of pool to generate the rate of linear DNA synthesis, good agreement between the pool parameters is found, provided that the ATP pool is measured in whole cell extracts, and assuming that the dATP and ATP pools equilibrate rapidly. RNA-synthesis rates were measured by using curve fits to equations developed by using the pool specific-radioactivity curves. The rate of synthesis of poly(A)-containing RNA varied in three experiments from 90 to 220mol/min per cell, with half-life of nuclear processing of 12-22 min with a mean of 16 min. Ribosomal RNA is synthesized at a rate of 70-200 mol/min per cell with an average half-life of nuclear processing of 37 min for the 18S RNA and 214 min for the 28S RNA. When the stable rRNA components are subtracted from the nRNA synthesis, the rate of nRNA synthesis is between 2 and 6fg/min per cell with an average half-life of degradation of 27 min. The rate of synthesis of poly(A)-containing RNA is 1.5-3.5% of the RNA-synthesis rates. These rates are compared with the RNA-synthesis rates found in L cells and concentrations of globin mRNA found in various erythroid-cell preparations.

Animals↗
PubMed1976

Evaluation of the normal range of values for uptake of radioactive iodine by the thyroid gland.

Uptake of radioactive iodine by the thyroid gland after oral administration of 75 muCi was determined in 1971-72 in 60 euthyroid female volunteers from the North Shore of Vancouver. Values were as low as 3% at 4 hours and 7% at 24 hours in subjects otherwise proven to be euthyroid. The highest values found were 13 and 26% at 4 and 24 hours. The effective thyroxine ratios were all within the accepted normal range. However, more than half of the volunteers showed some enlargement of the thyroid gland. These results suggest an increased iodine pool in the subjects, the likley source being iodine in mild, dairy products and erythrosine, a colouring agent in foods and pharmaceutical products. Potassium iodate, used sometimes in bread baking, contributed little to this pool in our sample. Subjects were, on the average, 9 to 25% heavier than their peers 20 years ago.

Adult↗
PubMed1976

The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid.

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2',3' hydroxyl end-groups is linked through the normal 3'--5' phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2',3 hydroxyl group is revealed. This structure could be a 5'-linked 5'-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3' end plus fragments that are not found after stepwise degradation. These fragments have a charge of --6 and --8 from pancreatic ribonuclease or --7 from ribonuclease T1 digestion. These charges are changed to --3.4 and --4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5' sequences m7G(5')ppp'AmpYpGp ... and m7G(5')pppAmpApGpYp.

Animals↗
PubMed1976

Carcinoma of the esophagus in Africans: establishment of a continuously growing cell line from a tumor specimen.

Biopsy material, from a patient with an esophageal carcinoma of a type occurring relatively frequently in Africans in some regions of Southern Africa, has been adapted to cell culture conditions and has developed into a continuously growing tumor cell line. The cells have a squamous pattern of growth which they maintain, without piling up, even in heavily confluent cultures.

Adenoviruses, Simian↗
PubMed1975

Total parenteral nutrition. A review.

Surgery, trauma, severe sepsis and burns are the most demanding physical stresses that a patient is likely to suffer, yet until recently, the nutrition of these patients was usually completely ignored. The concept of adequate feeding by the intravenous route is now well accepted and the authors present a review of many of the appropriate preparations which are available in South Africa, as well as a description of several regimens that have been successful in total parenteral nutrition (TPN).

Adult↗