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Biomedical subjects

J J Taljaard

Publications and source records attributed to J J Taljaard.

At least 109 records · Page 6Linked to original sources
PubMed1986

Endocrine responses after thyrotrophin-releasing hormone stimulation and dexamethasone suppression tests in the major depressive syndrome.

The effects of dexamethasone 1 mg on plasma cortisol levels and of thyrotrophin-releasing hormone (TRH) 200 micrograms on thyrotrophin (TSH), growth hormone and prolactin levels in 107 patients with a major depressive disorder (MDD) were compared with those in 87 healthy subjects. Individual hormonal responses and combinations of hormonal responses after administration of dexamethasone and TRH were evaluated as diagnostic aids for MDD by calculating sensitivity, specificity and efficiency for single and multiple hormonal abnormalities. In patients suffering from MDD, 65% of men, 74% of reproductive women and 71% of menopausal or hysterectomized (H/M) women had abnormal responses (sensitivity) to a dexamethasone suppression test (DST). When the DST and TSH responses to TRH were combined, 85% of men, 87% of reproductive women and 84% of H/M women had abnormal results. If the efficiency of the different combinations of hormone responses is calculated, a totally different picture emerges.

Adult↗
PubMed1986

Genetic differences in the endocrine responses to the thyrotrophin-releasing hormone stimulation test in patients with a major depressive episode.

The thyrotrophin-releasing hormone (TRH) stimulation test is becoming useful in the diagnosis of depression, but the optimum concentration of TRH required remains uncertain. The test was performed on a carefully selected group of patients with primary unipolar major depressive episodes with melancholia, who were severely depressed, using TRH 200 micrograms and 500 micrograms (groups 1 and 2). The thyroid-stimulating hormone (TSH), growth hormone (GH) and prolactin (PRL) levels were measured in response to TRH. Responses obtained were compared with respect to hormonal and genetic subgroups. Comparing groups 1 and 2 revealed significant differences in the GH responses (P = 0,0059). A similar significant difference was found in the GH response (P = 0,0102) elicited by the women in each group. Comparison of the genetic subgroups of groups 1 and 2 revealed a significant difference in the PRL response of both the genetic spectrum (P = 0,0258) and the group without a genetic history (P = 0,0259) of alcoholism or depression. The TSH response in the genetic spectrum group was also significantly higher (P = 0,0008) in group 2. Further investigations of the responses elicited in the different genetic subgroups may reveal important variables for the investigation of the pathogenesis of depression.

Alcoholism↗
PubMed1986

Substrate dependency of specific and non-specific estrogen-2/4-hydroxylase activities measured by the radio-enzymatic method in rat brain microsomes.

Putative specific and non-specific estrogen-2/4-hydroxylase activities which might affect the radio-enzymatic assay were characterized in terms of their requirements for NADPH and their substrate dependency. Using rat brain microsomes and partially purified rat liver COMT three main sources of estrogen-2/4-hydroxylase activity could be distinguished; a COMT-related component and NADPH-dependent and NADPH-independent microsomal components. The COMT-related activity required NADPH and showed about equal preferences for estrone and estradiol. The NADPH-dependent component was highly specific for estradiol, the relative activities observed with estrone and estriol being 7 and 1% of that observed with estradiol. The NADPH-independent component exhibited substrate saturation, was heat-labile and could not be inhibited by alpha-naphthoflavone or metyrapone. It showed a preference for estrone over estradiol, with estriol being a very poor substrate. These findings indicate that non-enzymatic factors contribute very little to product formation in the radio-enzymatic assay. The specificity of the major NADPH-dependent microsomal component towards estradiol suggests a stereo-specific requirement for the D-ring configuration of this estrogen. The use of no-cofactor blanks in the radio-enzymatic assay may be very important when different estrogens are compared as substrates for estrogen-2/4-hydroxylases.

Animals↗
PubMed1986

Alpha 2-adrenoceptor levels on platelets of patients with major depressive disorders.

3H-p-Aminoclonidine binding to platelets of patients with primary, unipolar major depressive disorder was compared to that of a normal healthy control population. The variances of platelet alpha 2-adrenoceptor Kd and Bmax values in patients were significantly greater than in the control group. No significant difference could be demonstrated between the Kd values of the two different groups, but the Bmax value of the depressed group was significantly lower than that of controls. We propose that an abnormal platelet alpha 2-adrenoceptor density may be used as a biological marker for major depressive disorder.

Adult↗
PubMed1986

Imipramine binding sites on platelets of patients with major depressive disorder.

3H-Imipramine binding to platelets of patients with primary, unipolar major depressive disorder was investigated and compared to that of a normal, healthy control population. No significant differences could be demonstrated between either the Kd or the Bmax values of the two groups. A negative correlation was observed between imipramine Bmax values and the Hamilton anxiety ratings of the depressed patients. Patients who displayed psychomotor retardation tended to have lower platelet imipramine Bmax values than patients with psychomotor agitation. It is suggested that platelet imipramine Bmax values may be a biological marker for subtypes of depression.

Adult↗
PubMed1986

Ethanol drinking by vervet monkeys (Cercopithecus pygerethrus): individual responses of juvenile and adult males.

Unrestricted access of vervet monkeys to a palatable solution of ethanol resulted in chronic intake or abstinence. Self-selected dose averaged 4.42 g/kg body mass/day. Growth of juveniles was not grossly affected. In plasma, chronic ethanol intake was associated with lower average K and Cl values, increased gamma glutamyl transpeptidase in some adults, and higher average total cholesterol. Neither hepatic histology nor haematology were affected by chronic ethanol intake.

Age Factors↗
PubMed1986

A previously undescribed ectodermal dysplasia of the tricho-odonto-onychial subgroup in a family.

We encountered two family members with a previously undescribed pure ectodermal dysplasia. The propositus exhibited hypotrichosis, hypodontia, focal linear dermal hypoplasia on the tip of her nose, irregular hyperpigmentation on her back, bilateral amastia and athelia, and mild nerve hearing loss. Her mother displayed similar characteristics, except for present, although hypoplastic, areolae and nipples. Both mother and daughter appeared to be clinically euhidrotic. Despite a comprehensive endocrine workup, the only abnormality detected was a suboptimal cortisol response to hypoglycemia in the propositus. Five other family members seemed to be affected. The pattern of inheritance appeared to be autosomal-dominant, with variable penetrance and expressivity.

Abnormalities, Multiple↗
PubMed1985

Acetylated fetal haemoglobin in neonates born to mothers with established and gestational diabetes.

Birth weight ratios (BWRs) and cord blood C-peptide values were significantly higher in neonates born to mothers with well-controlled gestational diabetes (GD) than in those born to mothers with well-controlled established diabetes (ED) or mothers with normal results on glucose tolerance testing. The neonates born to the ED mothers had the highest cord blood acetylated fetal haemoglobin (Hb F1) values, and these values correlated with cord C-peptide values. The cord C-peptide values in the GD group correlated with BWRs, but not with Hb F1 values. These results suggest differential tissue utilization of glucose in neonates born to mothers with different types of diabetes.

Birth Weight↗
PubMed1985

Value of glycosylated haemoglobin determination in diabetic pregnancy.

A single measurement of total maternal glycosylated haemoglobin (Hb A1) in the late third trimester of a diabetic pregnancy is of limited value in assessing diabetic control. There was no significant correlation between maternal Hb A1 values and neonatal C-peptide values or birth-weight ratios. An isolated Hb A1 measurement is not sufficiently sensitive to monitor the control of diabetes during pregnancy nor is it useful in predicting perinatal outcome.

Adult↗
PubMed1985

Effect of chronic desipramine treatment on adrenoceptor modulation of [3H]dopamine release from rat nucleus accumbens slices.

The effects of alpha 2- and beta-adrenoceptor agonists on the 25 mM K+-induced release of [3H]dopamine [( 3H]DA) from the nucleus accumbens slices of chronic desipramine (DMI)- and saline-treated rats were investigated using a superfusion technique. The K+-induced release of [3H]DA from nucleus accumbens slices was shown to be Ca2+ dependent and to be enhanced by ascorbic acid. In experiments with isoproterenol, ascorbic acid was added to the superfusion media in order to prevent the otherwise rapid oxidation of the drug. The K+-induced release of [3H]DA from nucleus accumbens slices of saline-treated rats was significantly decreased by the alpha 2-adrenoceptor agonist, clonidine (10 microM; 89 +/- 2.4% of control values; P less than 0.002), and significantly enhanced by the beta-adrenoceptor agonist, isoproterenol (1 and 10 microM; 122 +/- 4.3 and 171 +/- 2.9% of control values, P less than 0.002 and P less than 0.001, respectively). The basal release of [3H]DA was strongly enhanced by 10 microM but not 1 microM isoproterenol. Chronic DMI pretreatment (10 mg/kg i.p. for 28 days) did not significantly alter the K+-induced release of [3H]DA. Chronic DMI treatment attenuated the alpha 2-adrenoceptor-mediated inhibition of [3H]DA release, while the beta-adrenoceptor-mediated stimulation remained unchanged. The net effect of chronic DMI treatment therefore would appear to be a facilitation of dopaminergic neurotransmission in the mesolimbic system. This is consistent with behavioural evidence which suggests that the function of the mesolimbic dopaminergic reward system is facilitated by chronic treatment with antidepressant drugs.

Animals↗
PubMed1985

Evidence of hypoxaemia and distribution of minor haemoglobin components in the cord blood of neonates born to diabetic mothers.

The oxygenation status of normal and diabetic (White's classification A and B) mothers and their neonates was investigated. The diabetic patients had significantly increased maternal total haemoglobin and P50 values and the percentage of fetal haemoglobin was increased in cord blood taken at delivery in this group. There was a significant positive correlation between maternal P50 values and the percentage of fetal haemoglobin in cord blood. The cord blood 2,3-diphosphoglycerate, inorganic phosphate and P50 values were also increased in neonates born to diabetic mothers and these infants had a significantly increased birth weight ratio. The results are consistent with the presence of fetal hypoxaemia in the late third trimester of diabetic pregnancy in which obvious maternal vascular disease has been excluded.

Female↗
PubMed1985

Prostaglandin effects in the neuroendocrine mammalian brain.

Various prostaglandins (PGs) have been found in several areas of the brain. PGs of the E series have been found in the pituitary and pineal glands and the median eminence, and they have been shown to influence hypothalamic endocrine-release characteristics and release of melatonin from the pineal gland. It has been suggested that they may act, along with membrane phospholipids, as a link between neuronal depolarization, calcium uptake and neurotransmitter release. They may also influence postsynaptic effects of neurotransmitters. These latter effects may be due to interaction with membrane phospholipid- and cyclic nucleotide-induced changes of specific protein kinases. The PGs may act as intracellular mediators of neuro-endocrine control.

Animals↗
PubMed1985

Mseleni joint disease. Part I. An animal model?

Rats fed maize-based diets approximating to that eaten by blacks at risk of Mseleni joint disease developed fibrous osteodystrophy and nutritional secondary hyperparathyroidism, thought to be due to dietary calcium deficiency. This suggests that a dietary cause for this disease needs to be investigated further.

Animals↗
PubMed1985

Effects of combined administration of L-tryptophan and tricyclic antidepressants on alpha 2- and beta-adrenoceptors and monoamine levels in rat brain.

In order to test whether co-administration of a serotonin precursor with antidepressant drugs could potentiate the effects of the antidepressants on monoamines or adrenoceptors in rat brain, L-tryptophan (20 mg/kg) was administered to rats daily for 7 or 15 days, either alone or in combination with desipramine (10 mg/kg) or amitriptyline (10 mg/kg). After treatment with L-tryptophan for 7 days, increases were observed in rat hypothalamic and frontal cortex 5-hydroxy-3-indoleacetic acid levels as well as in hypothalamic dopamine and nucleus accumbens 3,4-dihydroxyphenylacetic acid levels. After 15 days, hippocampal beta-adrenoceptor density was found to be decreased. There was no evidence of potentiation of desipramine or amitriptyline action when L-tryptophan was administered in combination with the antidepressants. On the contrary, the antidepressants appeared to interact with L-tryptophan to reduce its effects.

Amitriptyline↗
PubMed1985

Evidence that estradiol-2/4-hydroxylase activities in rat hypothalamus and hippocampus differ qualitatively and involve multiple forms of P-450: ontogenetic and inhibition studies.

Estradiol-2/4-hydroxylase activity was studied in hypothalamic and hippocampal microsomes of male and female Wistar rats between 22 and 75 days after birth. The activity exhibited substrate saturation (50-100 microM estradiol) required NADPH and was inhibited by carbon monoxide, alpha-naphthoflavone and metyrapone. With 30 microM estradiol, 50% inhibition required 50-70 microM alpha-naphthoflavone compared to 200 microM metyrapone. Metyrapone exhibited biphasic inhibition curves which did not differ significantly between hypothalamus and hippocampus, whereas alpha-naphthoflavone was a more potent inhibitor of the hippocampal enzyme than of the hypothalamic enzyme. The Km and Vmax of the hippocampal estradiol-2/4-hydroxylase were significantly greater than that of the hypothalamus in both sexes at all ages studied. In female rats the Km of the hypothalamic enzyme changed from 14 microM at 23 days of age, to 47 microM at 71 days, but remained constant at about 29 microM in males. The Km of the hippocampal enzyme showed no significant change with age in either sex. The present findings indicate that catechol estrogen formation in the brain is catalyzed by multiple forms of microsomal P-450. They also suggest that these enzyme activities in the rat hypothalamus and hippocampus differ qualitatively. Ontogenetic changes in the Km of estradiol-2/4-hydroxylases appeared to be limited to the female hypothalamus. This might reflect a specific biological requirement of the female hypothalamus during critical stages of sexual differentiation of the brain. The relatively high hippocampal activity might reflect the catalytic versatility of different P-450 isozymes and does not necessarily imply a physiologically meaningful role with respect to catechol estrogen biosynthesis in this particular brain area.

Aging↗