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Biomedical subjects

D Suter

Publications and source records attributed to D Suter.

49 records · Page 3Linked to original sources
PubMed1983

Digital dermatoglyphics of the Faroe Islanders.

Finger dermatoglyphics of 446 male and 463 female Faroe Islanders are described. According to birthplace information for their grandparents the individuals sampled are considered to be representative of all regions of the Faroes. Pattern frequencies are given for individual digits and the tables contain mean radial, ulnar, and unilateral maximal ridge counts. Overall frequencies of patterns and mean total ridge counts in both sexes are compared with other populations in northwestern Europe, several of which have had close historical connections with the Faroes. The Faroese have exceptionally high frequencies of arch and ulnar loop patterns, making their mean pattern intensity index values among the lowest in Europe. Low mean total ridge counts are also characteristic of this population. Icelanders show closer dermatoglyphic resemblance to the Faroese than any other European populations. Low mean total ridge counts among Shetland and Orkney Islanders are noteworthy, and it is possible that the resemblance between these North Atlantic island populations is due to common ancestry arising from Viking settlement during the 8th and 9th centuries. The operation of random genetic drift on the gene pool of the Faroe Islanders is another factor to be considered when assessing their biological affinities.

Demography↗
PubMed1978

Subcellular localization of gamma-glutamyltransferase in calf thymocytes.

The subcellular localization of gamma-glutamyltransferase in calf thymocytes was investigated and compared with that of alkaline phosphodiesterase I, alkaline nitrophenyl phosphatase, succinate-tetrazolium oxidoreductase (succinate-INT reductase) and lactate dehydrogenase after two different methods of cell disruption and differential centrifugation. Most of the activity was recovered in the crude membrane fractions (43.0%), but significant amounts co-pelleted with the large-granule (mitochondria) fractions (31%). The specific activity of the gamma-glutamyltransferase in the purified plasma membrane was 30-50 times that of the enzyme in the cell homogenate and had a similar subcellular distribution to the plasma-membrane markers, alkaline phosphodiesterase I and alkaline nitrophenyl phosphatase. It was concluded that gamma-glutamyltransferase was primary a plasma-membrane-bound enzyme, and that its location in other subcellular fractions was probably due to their contamination with plasma-membrane vesicles.

Animals↗
PubMed1978

Mode of action of alpha-chlorohydrin as a male anti-fertility agent. Inhibition of the metabolism of ram spermatozoa by alpha-chlorohydrin and location of block in glycolysis.

1. The effect of alpha-chlorohydrin on the metabolism of glycolytic and tricarboxylate-cycle substrates by ram spermatozoa was investigated. The utilization and oxidation of fructose and triose phosphate were much more sensitive to inhibition by alpha-chlorohydrin (0.1-1.0mm) than lactate or pyruvate. Inhibition of glycolysis by alpha-chlorohydrin is concluded to be between triose phosphate and pyruvate formation. Oxidation of glycerol was not as severely inhibited as that of the triose phosphate. This unexpected finding can be explained in terms of competition between glycerol and alpha-chlorohydrin. A second, much less sensitive site, of alpha-chlorohydrin inhibition appears to be associated with production of acetyl-CoA from exogenous and endogenous fatty acids. 2. Measurement of the glycolytic intermediates after incubation of spermatozoal suspensions with 15mm-fructose in the presence of 3mm-alpha-chlorohydrin showed a ;block' in the conversion of glyceraldehyde 3-phosphate into 3-phosphoglycerate. alpha-Chlorohydrin also caused conversion of most of the ATP in spermatozoa into AMP. After incubation with 3mm-alpha-chlorohydrin, glyceraldehyde 3-phosphate dehydrogenase and triose phosphate isomerase activities were decreased by approx. 90% and 80% respectively, and in some experiments aldolase was also inhibited. Other glycolytic enzymes were not affected by a low concentration (0.3mm) of alpha-chlorohydrin. Loss of motility of spermatozoa paralleled the decrease in glyceraldehyde 3-phosphate dehydrogenase activity. alpha-Chlorohydrin, however, did not inhibit glyceraldehyde 3-phosphate dehydrogenase or triose phosphate isomerase in sonicated enzyme preparations when added to the assay cuvette. 3. Measurement of intermediates and glycolytic enzymes in ejaculated spermatozoa before, during and after injection of rams with alpha-chlorohydrin (25mg/kg body wt.) confirmed a severe block in glycolysis in vivo at the site of triose phosphate conversion into 3-phosphoglycerate within 24h of the first injection. Glyceraldehyde 3-phosphate dehydrogenase activity was no longer detectable and both aldolase and triose phosphate isomerase were severely inhibited. Spermatozoal ATP decreased by 92% at this time, being quantitatively converted into AMP. At 1 month after injection of alpha-chlorohydrin glycolytic intermediate concentrations returned to normal in the spermatozoa but ATP was still only 38% of the pre-injection concentration. Motility of spermatozoa was, however, as good as during the pre-injection period. The activity of the inhibited enzymes also returned to normal during the recovery period and 26 days after injection were close to pre-injection values. 4. An unknown metabolic product of alpha-chlorohydrin is suggested to inhibit glyceraldehyde 3-phosphate dehydrogenase and triose phosphate isomerase of spermatozoa. This results in a lower ATP content, motility and fertility of the spermatozoa. Glycidol was shown not to be an active intermediate of alpha-chlorohydrin in vitro.

Animals↗
PubMed1977

Fractionation of membrane vesicles. II. A method for separation of membrane vesicles bearing different enzymes by free-flow electrophoresis.

Free-flow electrophoresis was used to subfractionate membrane vesicles from calf thymocyte plasma membranes. The fractionation resulted in a separation of vesicle populations bearing four different enzymes: alkaline nitrophenyl-phosphatase (orthophosphoric-monoester phosphohydrolase (alkalin optimum) EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), (Mg2+ + Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) and acyl-CoA:lysophosphatidylcholine acyltransferase (acyl-CoA:1-acylglycero-3-phosphocholine-O-acyltransferase, EC 2.3.1.23). The specific content of cholesterol and total phospholipid coincided with the distribution of membrane-bound protein. However, vesicles migrating towards the cathode had a higher molar ratio of cholesterol to phospholipid (0.75) compared to those migrating to the anode (0.55). Sodium dodecyl sulphate-gel electrophoresis of pooled vesicle fractions also demonstrates distinct differences in their protein pattern. Electron-micrographic thin sections show that the vesicle populations have a similar morphology and size distribution. These results are discussed in terms of heterogeneity of the original thymocytes, contamination with intracellular membranes and a heterogeneous structure of the plasma membrane.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1976

Regulation of carbohydrate metabolism in lymphoid tissue. Nature of the endogenous substrates and their contribution to the respiratory fuel of the sliced rat spleen in vitro.

1. Tissue glycogen contributes, maximally, only 10% of the respiratory fuel of the rat spleen slice in the absence of an added carbon source, and makes no significant contribution when glucose (3mM) is added. 2. The reserves of fatty acid in the form of triglyceride (35.5mumol of fatty acid/g dry wt. of tissue) fall by approx. 25% after incubation of spleen slices with or without added glucose for 2h, and , on this basis, account for 32% of the oxidative fuel. 3. In contrast, the total oxidative contribution of fatty acid reserves to the respiratory fuel, determined on the basis of inhibiton of respiration by 2-bromostearate, is 42-52%. This range includes tissue from both starved and well-fed animals and is not significantly altered by the presence of added glycose (3mM). 4. Large quantities of NH3 (31-35mumol//h per g dry wt. of tissue) are produced by spleen slices incubated in the absence of added substrates, and this value is suppressed by approx. 50% on incubation with glucose (3mM). Adenine nucleotide breakdown can account for only 17% of the total ammonia produced. 5. Individual free amino acid concentrations in spleen were determined, both in vivo and in slices before and after 60 min of incubation. Although the total free amino acid pool size increases by 45% during incubation, owing to protein breakdown, the tissue concentrations of aspartate, glutamate, glutamine and alanine do not increase. It is suggested that these amino acids areoxidized in a net sense to CO2 and water with the liberation of free NH3 via transamination reactions, glutaminase, the purine nucleotide cycle and the tricarboxylic acid cycle. 6. It is concluded that the normal endogenous metabolism of sliced rat spleen (43-52% due to lipids, 30% due to amino acids and 10% due to glycogen) is modified by added glycose only to the extent that glycogen oxidation and 50% of the contribtion made by ino acids are suppressed; endogenous lipid metabolism is unaffected.

Amino Acids↗
PubMed1975

Regulation of carbohydrate metabolism in lymphoid tissue. Quantitative aspects of [U-14C]glucose oxidation by rat spleen slices.

When washed spleen slices from fed rats are incubated with 3 mm-[U-14C]glucose, the rate of glucose utilization (46.2 mumol/h per g dry wt.) is sufficient to account, theoretically, for 80% of the O2 consumption. Measurement of net lactate production, however, and the fate of the radioactive carbon, indicates that the contribution of glucose to the respiratory fuel of the tissue is only 25-30% whereas 60-70% of the glucose utilized is converted into lactate. At saturating glucose concentrations (above 5 mm) its contribution to the respiratory fuel of the slice is increased to a maximum value of 34-39%. Only 2% of the glucose utilized is metabolized via the oxidative steps of the pentose phosphate pathway. Starvation for 72 h marginally increases both the rate of glucose utilization (by 21%) and its net contribution to the respiratory fuel (by 29%). Insulin, glucagon, adrenaline and adenosine 3':5'-cyclic monophosphate have no significant effect on either the rate of glucose utilization or on the pattern of radioactive isotope distribution. The uptake of glucose is increased by only 20%, whereas the production of lactate doubles when slices are incubated under anaerobic conditions. In assessing the suitability of spleen slices for metabolic studies, the only serious major perturbation, compared with the freeze-clamped organ, is an elevated mitochondrial [NAD+]/[NADH] ratio (connected with increased endogenous NH3 production) that is partially restored to normal values on incubation with glucose. Equal proportions of erythrocytes and leucocytes are found in the washed spleen slice. Metabolic contributions of the constituent cell populations in the washed slice are calculated and it is concluded that lymphocytes account for the major part of the glycolytic metabolism (80-90%), whereas the contribution of erythrocytes is insignificant.

Adenosine Diphosphate↗
PubMedDate not supplied

Microanalysis of ultrasound vocalizations of young rats: assessment of the behavioral teratogenicity of methylmercury.

An on-line real-time computer system for the analysis of ultrasound vocalizations of rats is presented. The calls of young rats are recorded by an ultrasound microphone, transformed by an amplitude envelope and a frequency to voltage converter, digitized and stored by a microcomputer. The data management and analysis of the recorded vocalizations are entirely automated, allowing a high throughput of experiments in a routine laboratory. The frequency values are analyzed with respect to number, duration, base-interval, and mean frequency of the calls. Also, the frequency distributions of the call to call intervals, the call durations and the ultrasound frequencies, as well as the power spectra of the frequency modulations, are calculated. This system was used for the assessment of the behavioral teratogenicity of methylmercury chloride. Wistar rat dams were treated with 0, 1.5 or 5 mg/l in their drinking water from two weeks prior to pairing until the end of the experiment. The ultrasound vocalizations of two female and two male offspring per litter were recorded on days 5, 7, 9, 11, 13, and 15 for one minute in a clean glass beaker cooled to 20 degrees C. Methylmercury treatment resulted in a developmental delay and an overall reduction in the number of calls, a shortening of the base-interval and the call durations, a flattening and shift of the frequency distributions, and an alteration in the development with age of the frequency distributions. The frequency modulations of the calls also differed, their power being lower (smaller frequency variation) on several occasions.

Animals↗
PubMedDate not supplied

Hair colour in the Faroe and Orkney Islands.

Hair samples from 274 Faroe Islanders (mean age 16.7 years) and 246 Orkney Islanders (mean age 13.5 years) were classified and divided into eight colour categories by matching them to standard samples on the "Haarfarbentafel nach Fischer-Saller". Sex differences in the proportions in each category in both the Faroese (144 males, 130 females) and Orcadians (120 males, 126 females) were tested by x(2) and were not significant. A highly significant difference (1% level) was found in the proportions in the eight categories between the total Faroese and Orcadian samples. The Faroese subjects, despite their higher mean age, have a higher proportion of light-haired individuals. Hair of a "smoky-grey" tone, clearly unrelated to greying with age, and not represented on the Fischer-Saller scale, is reported and was found to be predominantly a feature of Orcadian males. The results for the Faroe and Orkney Islanders are compared with data for other North Atlantic populations.

Adolescent↗
PubMedDate not supplied

A developmental approach to the interpretation of dermatoglyphic data from Papua New Guinea and the Faroe Islands.

This study examines the influence of pattern intensity index (PII) on total ridge count (TRC) and the mean ridge count of whorls and ulnar loops. The date are principally finger print ridge counts and pattern types of 1005 Papua New Guineans (608 Waskia speakers from Karkar Island and 397 Yagaria speakers for Lufa sub District). In addition, in order to test whether some of the findings also apply to a dermatoglyphically very different population, data from a sample of 297 Faroe Islanders are analysed. The well known increase in TRC with PII is principally attributed to an increase in the mean ridge count of both whorls and ulnar loops, not as might be supposed to the increase in the proportion of whorls (overall the larger pattern type). The ratio of the larger ridge count to the smaller one provides a measure of whorl symmetry, which appears to increase with PII. The results are interpreted in terms of, and are in support of, the developmental hypothesis of dermatoglyphics reviewed by Mulvihill and Smith (1969).

Black People↗
PubMedDate not supplied

Regression analysis of digital ridge counts on pattern intensity index: a developmental interpretation.

Regression analyses of digital ridge counts on pattern intensity index (PII) are performed on data from three populations. The results for two Papua New Guinean populations (608 subjects from Karkar Island and 397 from Lufa sub District) are compared with those for a dermatoglyphically very different population from the Faroe Islands (296 subjects). Digital relationships are examined within each population. Equating the statistical regression of digital ridge counts with the embryological regression of apical volar pads, some biological interpretations of the findings are suggested. The results indicate that developmental fields across the embryological hand interact with genotype to produce digital differences in dermatoglyphic phenotype.

Denmark↗
PubMedDate not supplied

Evidence for a major gene effect in the distributions of digital ridge counts.

Previous attempts to isolate major gene effects in digital dermatoglyphics have been approached from two main directions. One has been concerned with analysing the components of total ridge count (TRC) distributions and examining various parameters of these distributions. The other has concentrated on the inheritance of various combinations of digital patterns. This study is primarily concerned with the shape of TRC and digital ridge count distributions. It suggests that a major gene effect may be as conspicuous in the distributions of digital counts as it is in TRC if these are viewed from the standpoint of global variation. The relationship between mean TRC, the standard deviation of TRC, skewness and kurtosis is examined and the results are compared with those obtained from a simple major locus model in which the overall distribution of TRC is composed of three overlapping normal distributions. As predicted by the model there is a negative correlation between mean TRC and its standard deviation, also a positive correlation with kurtosis. The expected relationship between mean TRC and skewness is non-linear, taking the form of an asymmetric U-shaped curve. There is evidence that the relationship between mean TRC and g1 in population samples covering a wide range of mean total ridge count follows this trend. The concordance between the predicted relationships and the observed frequency distributions is taken as evidence in favour of a single major locus hypothesis.

Dermatoglyphics↗