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Biomedical subjects

H Guyda

Publications and source records attributed to H Guyda.

At least 73 records · Page 4Linked to original sources
PubMed1978

Increased plasma somatomedin reactivity in chronic renal failure as determined by acid gel filtration and radioreceptor assay.

Plasma Somatomedin (SM) reactivity has been determined in patients with chronic renal failure and in normal children by radioreceptor assay (RRA) following acid gel filtration on Sephadex G-100. Total small molecular weight SM reactivity was obtained by the summation of all values between Kav 0.55 to 0.75. The mean SM reactivity (+/-SE) for the renal failure group (N = 9) was 154 +/- 10 ng/ml and for the normal subjects (N = 9) was 91 +/- 5 ng/ml (p less than .001). The renal failure group also had significantly increased mean levels of insulin, GH and PRL, but individual increases were not always concordant. Our data reveal that small molecular weight SM reactivity as determined by RRA of column eluates is increased in chronic renal failure compared to normal controls. Thus SM reactivity is not low in chronic renal failure, supporting the suggestion that peripheral antagonism to SM action contributes to the growth failure observed in these patients.

Adolescent↗
PubMed1978

Opiates, prolactin, and the dopamine receptor.

The administration of a dopamine antagonist, chlorpromazine, and two opiates, morphine and methadone, resulted in a significant rise in serum PRL within 90-150 min. Prior administration of dopamine receptor agonists (apomorphine, levodopa, aand bromocriptine) blocked this effect. In contrast, cyproheptadine, a serotonin antagonist, did not. We suggest that the opiates induce hyperprolactinemia in man via dopamine receptor blockade.

Apomorphine↗
PubMed1978

The effect of a slightly acidic somatomedin peptide (ILAs) on the sulphation of proteoglycans from articular and growth plate chondrocytes in culture.

Chondrocyte cultures were prepared from rabbit growth plate (GPC) and articular (ARC) chondrocytes. These two cell types have distinct morphological characteristics. The cells reached maximum numbers by days 10 and 21 for ARC and GPC, respectively. The proteoglycans (PG) contained in the cellular pool were extracted and purified by DEAE cellulose chromatography. The effect of a partially purified somatomedin peptide with insulin-like activity on [35S]sulphate incorporation into PG was evaluated. In both ARC and GPC a significant stimulation of [35S]sulphate uptake into PG subunits was obtained with 1 ng Eq./ml of somatomedin peptide. In order to obtain the same stimulatory effect with porcine insulin, a 1000-fold greater concentration was required. The electrophoretic patterns of the PG subunits on acrylamide-agarose electrophoresis were identical on control incubations and after stimulation with the somatomedin peptide. These data demonstrate in vitro biological activity of this peptide on well differentiated articular and epiphyseal growth plate chondrocytes in culture. These cultures appear to provide a sensitive biological assay for somatomedin peptides.

Animals↗
PubMed1978

The syndrome of basal encephalocele and hypothalamic-pituitary dysfunction.

We documented hypothalamic-pituitary dysfunction in three patients with congenital herniation of the brain through the base of the skull (basal encephalocele). All had growth hormone deficiency, although one has attained normal height. One had diabetes insipidus. Two had hypogonadotropic hypogonadism. Prolactin secretion was elevated in one, normal in another, and borderline low in the third. Two patients were euthyroid, but in response to thyrotropin-releasing hormone (TRH) injection, one patient's thyrotropin (TSH) level increased to levels exceeding normal while the other's did not attain normal levels. In the third patient, TSH response to TRH went from subnormal to normal after treatment with growth hormone and thyroxine. No patient had evidence of ACTH deficiency. These heterogeneous findings do not permit assignment of an unequivocal anatomic or functional site to the endocrine defect(s). Pituitary function should be evaluated in all patients with basal encephalocele, and this entity should be considered in the differential diagnosis of central endocrine malfunction.

Adult↗
PubMed1977

Effect of somatostatin on thyrotropin, prolactin, growth hormone and insulin responses to thyrotropin releasing hormone and arginine in healthy, hypothyroid and acromegalic subjects.

The effect of somatostatin on the thyrotropin (TSH), prolactin, growth hormone (GH) and insulin responses to the combined administration of thyrotropin releasing hormone (TRH) and arginine was studied in six healthy subjects, three hypothyroid patients and three acromegalic patients. Similar inhibition by somatostatin of the TSH and insulin responses was observed in the three groups. While the tetradecapeptide had no significant effect on the prolactin response in the healthy and acromegalic subjects, it caused an unexpected inhibition of the prolactin response in two of the hypothyroid subjects. Contrary to the findings in the healthy and hypothyroid subjects, somatostatin did not inhibit the GH response in the acromegalic patients. Normal inhibition by somatostatin of the insulin response, followed by a rebound in insulin secretion, was observed in all subjects. These preliminary data indicate increased sensitivity of the prolactin-secreting cells to somatostatin in hypothyroidism and suggest that decreased responsiveness of the somatotrophs to somatostatin could play a role in the pathogenesis of acromegaly.

Acromegaly↗
PubMed1977

Short term culture of human midterm and term placenta: parameters of hormonogenesis.

Monolayer cultures of human midterm and term placentae have been established following trypsin dispersion of placental minces. Maintenance of endocrine function was monitored by the concentrations of specific hormones in the culture media. At either gestational age the cultures 1) secret estradiol-17beta(1) and estrone (in a ratio of about 1:20) and aromatize 3H- or 14C-dehydroepiandrosterone sulfate and 14C-androstenedione, estrogen production being markedly enhanced by addition of dehydroepiandrosterone (10(-6)7) to the culture medium; 2) metabolize 3H-pregnenolone to progesterone and 14C-cortisol to cortisone; and 3) produce increasing amounts of chorionic gonadotropin and decreasing amounts of placental lactogen during the first week in culture. It is proposed that the model is highly suited to the study of factors affecting hormonogenesis by the human placenta whether they be of maternal or of fetal origin.

Chorionic Gonadotropin↗
PubMed1977

Dopaminergic function in two patients with catalepsy.

Apomorphine HC1 (2 mg subcutaneously), a dopamine receptor agonist, was administered to two schizophrenic patients with catalepsy. In one of these patients the clinical response to apomorphine was compared with that of sodium amytal and the growth hormone response apomorphine (0.75 mg subcutaneously) was compared with that of 25 control subjects. Apomorphine had no effect whereas sodium amytal caused rapid disappearance of catatonic symptoms including catalepsy. The peak growth hormone response to apomorphine was similar to that of controls. These data suggest that unlike experimental catalepsy in animals, catalepsy associated with schizophrenia may not be dependent on impaired dopaminergic function. Further case studies as well as the use of other dopamine receptor agonists are required before definite conclusions can be drawn.

Adult↗
PubMed1977

Effect of methysergide and pimozide on apomorphine-induced growth hormone secretion in men.

The dopamine receptor agonist, apomorphine HCl (0.75 mg sc) increased serum growth hormone (GH) concentrations in each of 6 subjects. This increase was not inhibited by pretreatment with the serotonin antagonist, methysergide, but was completely abolished in the 4 individuals pretreated with pimozide, a selective dopamine receptor blocking agent. These results provide further evidence that apomorphine-induced GH secretion is mediated by a dopaminergic mechanism and is independent of a serotonergic mechanism.

Apomorphine↗
PubMed1977

Ineffectiveness of pyridoxine (B6) to alter secretion of growth hormone and prolactin and absence of therapeutic effects on galactorrhea-amenorrhea syndromes.

The acute effect of pyridoxine (B6) on serum GH and PRL levels and its chronic effects on galactorrhea in nine subjects (group I, n=4, idiopathic galactorrhea with normal PRL levels and normal menses; Group II, n=5, galactorrhea-amenorrhea with increased PRL levels) have been studied. Pyridoxine did not acutely alter GH or PRL levels. There was no decrease in galactorrhea, no resumption of menses and no decrease in PRL following tow months of B6 therapy. In contrast, bromocriptine was effective in suppressing galactorrhea and restoring normal menses in group II subjects and remains the therapy of choice for this purpose.

Amenorrhea↗
PubMed1976

Thyroid function in neonatal hypothyroidism.

Various aspects of the thyroid function have been measured in 28 cases of neonatal hypothyroidism detected by means of the Quebec Screening Program for Metabolic Diseases. In all instances the T4 value in the blood of filter paper spot was below 2 SD of the mean of the day, averaging 0.39 +/- 0.04 ng/40 mul (mean +/- SEM) of eluted blood. The T4 value of a second similar sample averaged 0.22 +/- 0.04 ng/mul of eluted blood; this value was significantly lower than the first one. The serum T4 concentration was decreased in all the infants, whereas three of them had a normal serum TSH concentration. At least three groups of patients could be identified: (1) patients with primary thyroid failure, (2) those with secondary or tertiary hypothyrodism, and (3) those with abnormal synthesis of thyroid hormone.

Female↗
PubMed1976

TSH measurements from blood spots on filter paper: a confirmatory screening test for neonatal hypothyroidism.

A sensitive radioimmunoassay for the measurement of TSH in the eluate of blood spotted on filter paper has been developed. The method is consistently sensitive to 0.1 to 0.25 muU of TSH and enables the detection of values equivalent to 6 to 15 muU/ml of serum. The measurement of TSH in the filter paper spot in all infants with low filter paper spot T4 has permitted rapid confirmation of 10 cases of neonatal hypothyroidism. However, cases of hypothalamic hypothyroidism with low or normal filter paper spot TSH concentrations would have been missed using only this method. Since these patients represent approximately 10% of our neonatal hypothyroid population, we do not recommend this method as a primary screening procedure, but rather as a confirmatory test which will accelerate the diagnosis and therefore the onset of therapy.

Filtration↗
PubMed1976

Effect of apomorphine on growth hormone and prolactin secretion in schizophrenic patients, with or without oral dyskinesia, withdrawn from chronic neuroleptic therapy.

Serum growth hormone (GH) and prolactin (PRL) concentrations were measured after administration of the dopamine receptor agonist, apomorphine HC1 (0.75 mg subcutaneously), to 17 chronic schizophrenic patients, four of whom had an oral dyskinesia, who were withdrawn from chronic neuroleptic therapy for periods of two to 15 weeks, and in 21 control subjects (normal volunteers or physically healthy alcoholics not exposed to neuroleptics). Six of the schizophrenic patients, but none of the controls, had raised baseline levels of GH (greater than 6 ng/ml). After apomorphine all controls showed an increase in serum GH with a peak concentration of 9 ng/ml or more, whereas eight subjects withdrawn from neuroleptics showed an inadequate response (peak less than 6 ng/ml) and in two others an inadequate response was obtained on one of two trials. The peak GH concentration was significantly less after apomorphine in patients withdrawn from neuroleptics (11.90 +/- 3.19 ng/ml) compared with controls (20.80 +/- 2.11 ng/ml) (P less than 0.05). Among patients withdrawn from neuroleptics, those with an oral dyskinesia had significantly lower peak GH concentration 2.46 +/- 0.93 ng/ml) after apomorphine compared with those without (14.85 +/- 3.83 ng/ml) (P less than 0.05). There were no differences in serum PRL concentrations, before or after apomorphine administration, between patients withdrawn from neuroleptics and controls. In uncontrolled observations none of the four patients with an oral dyskinesia showed any worsening of the movement disorder after apomorphine. These data provide no evidence for supersensitivity of dopamine receptors in chronic schizophrenic patients withdrawn from chronic neuroleptic therapy.

Adult↗
PubMed1976

The effect of acetylsalicylic acid on TSH and PRL secretion after TRH stimulation in the human.

In order to study the effect of prostaglandins on TSH release in the human, Acetylsalicylic Acid was given to 9 normal subjects at doses necessary to obtain a salicylate level of 20 mg/dl. TRH, 400 mug was injected prior to and after the medication. Thyroid hormone parameters were measured at time 0, and TSH and PRL at time 10, 20, 30, 45 minutes after the injection. The free fraction of thyroid hormones remained constant during treatment but a significant decrease of TSH concentration (30%) was noted after TRH injection on Acetylsalicylic Acid treatment whereas no changes were noted for PRL. As noted in the animal, this study indicates that in the human, prostaglandins potentiate the effect of TRH on TSH liberation by the pituitary where it has no effect on PRL.

Adult↗
PubMed1975

Medical Research Council of Canada therapeutic trial of human growth hormone: first 5 years of therapy.

The Medical Research Council of Canada has initiated human growth hormone (hGH) therapy in 151 patients with documented complete hGH deficiency that was idiopathic in 76% of cases, secondary to craniopharyngioma (organic) in 17% and of varied cause in 7%. Approximately 50% of the patients with idiopathic disease had isolated hGH deficiency; during therapy thyroid deficiency developed in five patients and cortisol deficiency in three. A similar increase in mean height velocity occurred in the first treatment phase for patients less than 12 years old (0.93 plus or minus 0.30 cm/mo) and those 12 years and older (0.86 plus or minus 0.29 cm/mo). Although subsequent courses of hGH therapy yielded significantly diminished response in both age groups, this diminution was not progressive: the height velocity of the younger patients returned to 0.82 plus or minus 0.26 cm/ml in the fifth therapy phase. The mean height velocity attained at the optimal dosage (0.20 to 0.29 units/kg three times per week) for each age group did not differ significantly. Despite therapy being carried out for only 6 months of the year, normal increment ratios for height age and bone age against chronologic age were observed in the patients with idiopathic disease. In only four patients did treatment failure occur, and three of these were more than 20 years old. The addition of fluoxymesterone (10 mg/d) to the hGH therapeutic regimen (15 units/wk), when diminished response to hGH alone became evident, promoted an enhanced growth response in 9 of 11 older patients. These data indicate that age of the patient and dosage of hGH, but not diagnostic category, were important influences on the response to therapy. Younger patients responded best and maintained a higher mean growth velocity than older patients during intermittent hGH therapy

Adolescent↗
PubMed1975

Preliminary report on a mass screening program for neonatal hypothyroidism.

We have recently developed an immunoassay that can measure thyroxine rapidly and accurately in the eluate of 40 mul of dried blood spotted on filter paper at the fifth day of life. The method is completely automated and by using the samples received by the Central Laboratory of the Quebec Network for Genetic Medicine and their follow-up facilities, we are now screening every newborn in the province of Quebec for neonatal hypothyroidism. To date, from 47,000 measurements, three newborn infants with abnormally low TBG and seven hypothyroid infants have been detected. From these data we conclude that the frequency of congenital hypothyroidism is about one in 7,000 births and that our method is effective in detecting thyroid hormone abnormalities with an acceptable percentage of false positive measurements; no false negative results have occurred to our knowledge.

Blood Specimen Collection↗