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Biomedical subjects

J M Anderson

Publications and source records attributed to J M Anderson.

At least 361 records · Page 20Linked to original sources
PubMed1984

Plasma renin activity in the management of congenital adrenal hyperplasia.

Fourteen children with salt losing and five children with non-salt losing congenital adrenal hyperplasia were studied. Venous samples were collected for measurement of plasma renin activity, serum 17 alpha-hydroxyprogesterone, testosterone, sodium, and creatinine. Overnight urinary sodium and creatinine excretions were measured after collection on an outpatient basis. Eight 'salt losers' had a raised plasma renin activity despite mineralocorticoid treatment, as did one 'non-salt loser'. Six of the children in whom clinical and biochemical control was inadequate, including the 'non-salt loser', had an increase in the dose of fludrocortisone. When the investigations were repeated one month later, a fall in plasma renin activity accompanied by a fall in 17 alpha-hydroxyprogesterone in all but one patient were found. The dose of mineralocorticoid may be as critical as the dose of glucocorticoid in the management of congenital adrenal hyperplasia, and regular determination of plasma renin activity should be made, particularly if clinical control is difficult.

17-alpha-Hydroxyprogesterone↗
PubMed1983

Results of a comprehensive health survey in the Durbanville district, August - September 1980.

The results of a comprehensive health survey in the Durbanville district, apparently the first of its kind carried out in the Western Cape, are reported. It is shown that this type of investigation in a rural area is practical and possible. Factors making complete accuracy of the figures impossible were: (i) the fact that two separate operations were necessary, the first a 6-week pre-survey investigation to determine general health profiles and the second the week-long survey proper; (ii) the presence of a small migrant population resident outside the Durbanville area and fluctuations in the employee population; and (iii) the fact that the survey proper was carried out during a school vacation.

Health Surveys↗
PubMed1983

In vivo biocompatibility studies. I. The cage implant system and a biodegradable hydrogel.

A cage implant system has been utilized to examine the in vivo biocompatibility of a biodegradable hydrogel, poly(2-hydroxy-ethyl-L-glutamine) (PHEG). This system permits the quantitative determination of the components of the inflammatory exudate which surrounds the implanted polymer within the cage system. This system permits the serial examination of exudate components without sacrificing the animal. In addition, this system allows the subsequent removal of the polymer for surface and mechanical studies. Following implantation of the biodegradable hydrogel, quantitative and differential white cell counts of the exudates were determined over a 21-day period. In addition, concomitant extracellular enzyme analyses for alkaline phosphatase, acid phosphatase, prostatic acid phosphatase, leucine amino-peptidase, and Cathepsin B1 were determined. Corresponding control samples from exudates of the cage implant without the polymer were also determined. The two-tailed Student's t-test for unpaired samples was used to statistically compare the control and implanted polymer values for these respective analyses at the various time periods. A comparison of the cellular response for the control system and the PHEG system did not show statistically significant differences during the first 7 days following implantation. The acute inflammatory response, polymorphonuclear leukocyte predominant, was followed by a mild chronic inflammatory response, macrophage and lymphocyte predominant, and during this time period, 8-14 days, macrophages were present in significantly larger numbers for the PHEG system when compared to the control values. Enzymic analysis of the exudates revealed statistically significant differences between control and PHEG values at time intervals where no differences were noted in cell density or population. These results are discussed in terms of cell-polymer interactions leading to cellular activation and enhanced enzyme exocytosis by the inflammatory cells. Stress-strain measurements on implanted PHEG samples showed that significant in vivo degradation had occurred during the acute inflammatory phase of the response, i.e., the first 7 days.

Acid Phosphatase↗
PubMed1983

Type V collagen during granulation tissue development.

The collagen content, as determined by hydroxyproline assay, of experimental granulation tissue in rats was observed to increase rapidly 21 days, and less rapidly to 90 days of tissue development. Resistance of the collagen to pepsin digestion reached a maximum at 21 days, suggesting more extensive or more stable crosslinking at that time. Type V collagen and the expected collagen types I and III were present in pepsin extracts of the granulation tissue as determined by SDS-polyacrylamide gel electrophoresis. Over 3 months of tissue development the relative quantity of type V collagen, as evidenced by changes in the alpha B chain, varied in parallel with the changing vascularity of the tissue, suggesting an association with capillary endothelial cells and angiogenesis.

Animals↗
PubMed1983

The effect of advanced old age on the neurone content of the cerebral cortex. Observations with an automatic image analyser point counting method.

The effect of advanced old age on the nerve cell content of the cerebral cortex was examined in 19 non-demented persons aged 69-95 years, using a Quantimet 720 image analysing computer to make area proportion measurements. Neurone loss around 1.0% per annum was found both in the neocortex and in the medial hippocampus. There was also significant shrinkage of neurones in the hippocampus. Macroscopic measurements of the cerebral hemispheres by means of point-counting morphometry showed a corresponding reduction in the volume of white matter amounting to about 0.8% per annum, but only a minor change in the cortex volume. This finding is consistent with the occurrence of dendritic growth of surviving neocortical neurones. By contrast, there appears to be no compensatory dendritic proliferation in the medial hippocampus since tissue atrophy was commensurate with cell loss in this region.

Aged↗
PubMed1983

Localization of different photosystems in separate regions of chloroplast membranes.

The stoichiometric amounts and the photoactivity kinetics of photosystem I (PSI) and of the alpha and beta components of photosystem II (PSII(alpha) and PSII(beta)) were compared in spinach chloroplast membrane (thylakoid) fractions derived from appressed and nonappressed regions. Stroma-exposed thylakoid fractions from the nonappressed regions were isolated by differential centrifugation following a mechanical press treatment of the chloroplasts. Thylakoid vesicles derived mainly from the appressed membranes of grana were isolated by the aqueous polymer two-phase partition method. Stroma-exposed thylakoids were found to have a chlorophyll a/chlorophyll b ratio of 6.0 and a PSII(beta)/PSI reaction center ratio of 0.3. Kinetic analysis of system II photoactivity revealed the absence of PSII(alpha) from stroma-exposed thylakoids. The photoactivity of system I in stroma-exposed thylakoids showed a single kinetic component identical to that of unfractionated chloroplasts, suggesting that PSI does not receive excitation energy from the PSII-chlorophyll ab light-harvesting complex. Thus, stroma-exposed thylakoids are significantly enriched in both PSI and PSII(beta). Inside-out vesicles from the appressed membranes of grana-partition regions had a chlorophyll a/chlorophyll b ratio of 2.0 and a PSII/PSI reaction center ratio of 10.0. The photoactivity of system II showed the membranes of the grana-partition regions to be significantly enriched in PSII(alpha). We conclude that PSII(alpha) is exclusively located in the membranes of the grana partitions while PSII(beta) and PSI are located in stroma-exposed thylakoids. The low PSI reaction center (P700) content of vesicles derived from grana partitions and the kinetic homogeneity of the PSI complex suggest total exclusion of P700 as a functional component in the membrane of the grana-partition region.

Journal Article↗
PubMed1983

Photosensitivity in thiopyronine-resistant yeast mutants.

In yeast, thiopyronine (TP) acts both as a growth inhibitor (in the dark) and a photodynamic sensitizer (in the light). We have isolated a large number of TP-resistant mutants of Saccharomyces cerevisiae and characterized them by genetic and photobiological techniques. Resistance to the growth-inhibitory (dark) effects of TP can arise by mutations in at least four separate genes. Growth-inhibitory and photodynamic effects of TP can be genetically separated, as evidenced by the finding that resistance mutants affected in three of the genes were not altered in their photodynamic response to the dye. In contrast, a mutation in the fourth gene simultaneously conferred high resistance to both the growth-inhibitory and photosensitizing effects of TP, suggesting that a mutation had occurred at a step common to the expression of both effects. Preliminary data suggest that this mutation reduces the ability of the cells either to take up, or bind, TP.

Drug Resistance, Microbial↗
PubMed1983

Release of Sucrose from Vicia faba L. Leaf Discs.

The release of sucrose from leaf discs of Vicia faba L. to a bathing medium was studied for evidence of a relationship between this release and mesophyll export of photosynthate in vivo. Sucrose was released specifically over hexoses and represented over 85% of total photosynthate released. The sucrose appeared to be derived from the mesophyll tissue directly and release did not require concurrent photosynthesis. The data indicated two separate channels for sucrose release. The first was sensitive to inhibition by 1 millimolar p-chloromercuribenzenesulfonic acid and the second was promoted by lowering the Ca(2+) concentration below 0.1 millimolar. Flow through both channels was about equal when tissue that had been actively photosynthesizing for several hours was used. The rate of release was not dependent on the extracellular pH, but was inhibited by 10 micromolar carbonylcyanide p-trifluromethoxyphenylhydrazone. Lowering the Ca(2+) concentration below 0.1 millimolar or raising the K(+) concentration above 100 millimolar stimulated sucrose release. The stimulation by high K(+) was not reversed by adding Ca(2+). The data supported the postulate that Ca(2+) removal or K(+) addition changed the permeability of the mesophyll plasma membrane to sucrose.

Journal Article↗
PubMed1983

Difficulties in the diagnosis of congenital adrenal hyperplasia in early infancy: the 11 beta-hydroxylase defect.

Investigations of steroid metabolism in a newborn infant with steroid 11 beta-hydroxylase deficiency are described. Deficiency of this enzyme, like other forms of congenital adrenal hyperplasia (CAH) can be difficult to characterise in the neonatal period. In the first days of life the excretion of cortisol was low but most other hormonal parameters were normal and the major metabolite of 11-deoxycortisol (tetrahydro-S, THS) was not detectable in the urine. Using mass spectrometry, the presence of THS was confirmed in urine collected on the 12th day of life and from this time the excretion rates increased until approximately 300 micrograms were measured in urine on the 27th day of life. A new metabolite of 11-deoxycortisol was tentatively identified as 6 alpha-hydroxy-THS. This steroid is not a significant metabolite in 11 beta-hydroxylase deficiency at other periods of life.

Adrenal Cortex Hormones↗
PubMed1983

Clinical aspects of tracheobronchopathia osteochondroplastica.

Two patients with tracheobronchopathia osteochondroplastica are described, both presenting with features suggestive of bronchial carcinoma. They had a long standing history of recurrent haemoptysis. The characteristic bronchoscopic, radiological and histological features of the condition are illustrated and the clinical problems in diagnosis discussed.

Aged↗
PubMed1982

The role of chlorophyll-protein complexes in the function and structure of chloroplast thylakoids.

The photosynthetic pigments of chloroplast thylakoid membranes are complexed with specific intrinsic polypeptides which are included in three supramolecular complexes, photosystem I complex, photosystem II complex and the light-harvesting complex. There is marked lateral heterogeneity in the distribution of these complexes along the membrane with photosystem II complex and its associated light-harvesting complex being located mainly in the stacked membranes of the grana partitions, while photosystem I complex is found mainly in unstacked thylakoids together with ATP synthetase. In contrast, the intermediate electron transport complex, the cylochrome b-f complex, is rather uniformly distributed in these two membrane regions. The consequences of this lateral heterogeneity in the location of the thylakoid complexes are considered in relation to the function and structure of chloroplasts of higher plants.

Chlorophyll↗
PubMed1982

Transbilayer organization of the chlorophyll-proteins of spinach thylakoids.

To investigate the transverse bilayer organization of the chlorophyll-proteins of the three intrinsic chlorophyll-protein complexes, the effects of proteolytic enzymes, and an antibody against the light-harvesting complex were compared using right-side-out and inside-out thylakoid vesicles. The vesicles were isolated by aqueous polymer phase partitioning following the fragmentation of spinach thylakoids by passage through a Yeda press. Both vesicle types were agglutinated by an antiserum specific for the light-harvesting complex, although proteolytic degradation of the complex occurred only in right-side-out vesicles. In addition, there are different antigenic sites for the light-harvesting complex on the inner and outer thylakoid surfaces. Polypeptides of the chlorophyll-alpha-protein complex of photosystem II were degraded by proteases at both membrane surfaces. We concluded that both these chlorophyll-protein complexes are membrane spanning and transversely asymmetric, but that the light-harvesting complex polypeptides accessible at the inner thylakoid surface are more resistant to proteolytic attack. In contrast, the main chlorophyll-containing polypeptide (Mr = 64 500) of photosystem I complex was resistant to proteolytic attack at both the outer and inner thylakoid surfaces.

Chlorophyll↗
PubMed1982

Hemostatic and healing studies of sodium amylose succinate (IP760).

Acute and chronic studies were performed in the canine model to evaluate a new topical hemostatic agent in terms of initial hemostatic capability and tissue/material interaction during the healing process. IP760, a porous amylose succinate material, was applied to large splenic surface wounds in six acute and twelve chronic animals. Microfibrillar collagen (Avitene) was used in twelve chronic animals for comparison. While the hemostatic capabilities of the two agents were comparable, marked differences were noted in the healing response. In the IP760-treated wound sites the acute inflammatory response, granulation tissue infiltration with fibrosis and healing occurred earlier and in a more homogeneous manner than in the Avitene-treated wound sites. Healing of the IP760-treated wounds occurred concomitantly with the development of granulation tissue and fibrosis and the rapid resorption of the IP760.

Administration, Topical↗