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Biomedical subjects

A Tait

Publications and source records attributed to A Tait.

At least 145 records · Page 8Linked to original sources
PubMed1981

Analysis of protein variation in Plasmodium falciparum by two-dimensional gel electrophoresis.

The proteins of cultured isolates of Plasmodium falciparum have been labelled with [35S]methionine and then examined for variation between isolates by the two dimensional gel electrophoresis system of O'Farrell. A large number (ca. 100) of proteins have been characterised in terms of their isoelectric point and molecular weight, and thirty five proteins have been compared in all isolates. These comparisons have been used to examine two main questions, namely whether there is any evidence for sub-speciation between isolates from W. Africa and S.E. Asia and whether there is evidence for variation between isolates from a single region in Thailand. The results show that small amounts of P. falciparum are sufficient for the study of variation in many proteins and that considerable variation occurs. These results are compared with those obtained by other workers, using enzyme electrophoretic variation, and the relative merits of the two methods are considered.

Animals↗
PubMed1980

Effect of counselling on the psychiatric morbidity associated with mastectomy.

A controlled trial was conducted to determine whether counselling by a specialist nurse prevented the psychiatric morbidity associated with mastectomy and breast cancer. Seventy-five patients were counselled by the nurse and monitored during follow-up, while 77 patients received only the care normally given by the surgical unit. Counselling failed to prevent morbidity, but the nurse's regular monitoring of the women's progress led her to recognise and refer 76% of those who needed psychiatric help. Only 15% of the control group whose condition warranted help were recognised and referred. Consequently, 12 to 18 months after mastectomy there was much less psychiatric morbidity in the counselled group (12%) than in the control group (39%). These findings highlight the high degree of psychiatric morbidity in patients who have undergone mastectomy and indicate the need to find ways of reducing this morbidity.

Anxiety Disorders↗
PubMed1980

Evidence for diploidy and mating in trypanosomes.

The question of whether any sexual process takes place at some stage of the life cycle of the trypanosome has often been raised and crosses between different drug-resistant strains have provided no convincing answer. Multinucleate forms of trypanosomes have been observed by electron microscopy but their significance and origin remain obscure. As part of a study aimed at examining the speciation and genetics of the Trypanosoma brucei complex of trypanosomes, a series of isolates from a population of T.b. brucei have been screened for electrophoretic variation in 19 enzymes. The results of this survey, reported here, provide strong evidence that trypanosomes are diploid and undergo random mating and recombination.

Animals↗
PubMed1980

Mitochondrial chromatin in Paramecium aurelia.

Chromatin-like structures have been observed in material extracted from the mitochondria of Paramecium aurelia and evidence is presented which establishes that these structures do not originate from nuclear contamination of mitochondrial preparations but are exclusively of mitochondrial origin. Extraction of these chromatin-like structures with dilute acid followed by gel electrophoresis of the extract shows the presence of five major basic proteins which are of similar electrophoretic mobility to histones. Digestion of mitochondrial extracts with endogenous nuclease, followed by electrophoresis of the extracted DNA, demonstrated that the mitochondrial genome is protected from nuclease digestion by regular repeating units very similar to those observed in the nuclease digestion of chromatin.

Animals↗
PubMed1979

The effect of N-(methoxy polyethylene glycol) rho-hydroxymercuribenzamide, a polymeric sulfhydryl group reagent, on spermatozoan motility.

The water-soluble, polymeric sulfhydryl group reagent N-(methoxypolyethylene glycol) rho-hydroxymercuribenzamide (Mw 5000) inhibited the motility of human spermatozoa. Its activity profile was very similar to that of rho-hydroxymercuribenzene sulfonate, a charged sulfhydryl group reagent that is a very poor membrane penetrant. These results suggest that functional sulfhydryl groups of the spermatozoan membrane are easily accessible and externally oriented on the membrane surface.

4-Chloromercuribenzenesulfonate↗
PubMed1978

Species identification in protozoa: glucosephosphate isomerase variation in the Paramecium aurelia group.

Results are presented for intra- and interspecies variation in electrophoretic mobility of the enzyme glucosephosphate isomerase in the Paramecium aurelia species complex. Three new observations have been made: (1) the hitherto indistinguishable species 1 and 5 can be distinguished on the basis of GPI electrophoretic mobility, (2) the degree of intraspecies variation is much higher for GPI than for the previously studied mitochondrial dehydrogenases and esterases, and (3) several of the enzymatic variants observed in one species are apparently indistinguishable from some found in other species. The intraspecies variants found have been shown to be allelic, and, on the basis of the enzyme patterns of the heterozygotes, it is proposed that GPI is a dimeric enzyme determined by two loci. In view of the use of enzyme variation as a means of species identification in protozoa, these results suggest that the use of such methods can lead to underestimating the number of species and possibly to misclassification. The implications of these findings together with the results obtained with Tetrahymena are discussed.

Animals↗
PubMed1977

Characterization of mitochondrial and cytoplasmic ribosomes from Paramecium aurelia.

The ribosomes extracted from the mitochondria of the ciliate, Paramecium aurelia, have been shown to sediment at 80S in sucrose gradients. The cytoplasmic ribosomes also sediment at 80S but can be distinguished from their mitochondrial counterparts by a number of criteria. Lowering of the Mg++ concentration, addition of EDTA, or high KCl concentrations results in the dissociation of the cytoplasmic ribosomes into 60S and 40S subunits, whereas the mitochondrial ribosomes dissociate into a single sedimentation class at 55S. Furthermore, the relative sensitivity of the two types of ribosome to dissociating conditions can be distinguished. Electron microscopy of negatively stained 80S particles from both sources has also shown that the two types can be differentiated. The cytoplasmic particles show dimensions of 270 X 220 A whereas the mitochondrial particles are larger (330 X 240 A). In addition, there are several distinctive morphological features. The incorporation of [14C]leucine into nascent polypeptides associated with both mitochondrial and cytoplasmic ribosomes has been shown: the incorporation into cytoplasmic 80S particles is resistant to erythromycin and chloramphenicol but sensitive to cycloheximide, whereas incorporation into the mitochondrial particles is sensitive to erythromycin and chloramphenicol but resistant to cycloheximide.

Animals↗
PubMed1975

DNA-dependent DNA polymerase activities from Paramecia macronuclei.

Three DNA-dependent DNA polymerase activities, A, B, and C, have been detected from the macronucleus of Paramecium. The enzymes were separated and partially purified by DEAE-cellulose and phosphocellulose chromatography. These three enzymes can be further distinguished from each other by the effect of KCl, araCTP and different DNA templates on their activities. All three enzymes have the same molecular weight (900 000-110 000), are dependent on Mg2+ and added DNA template and are inhibited by sodium pyrophosphate. The relative amounts of the three enzyme activities vary with the growth stage of the Paramecia from which they are isolated. In balanced growth, three polymerase activities (A, B AND C) are observed, whereas in late log or stationary phase polymerase C is absent, while the level of polymerase B decreases by a larger factor than polymerase A. These results have been related to the possible functional roles of the three activities and their relationship to activities in other organisms studies is discussed.

Animals↗