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Biomedical subjects

P Ball

Publications and source records attributed to P Ball.

At least 109 records · Page 6Linked to original sources
PubMed1988

Comparative study of hormonal counterregulation during GCIIS-guided hypoglycemia tests using human proinsulin and human insulin (recombinant DNA).

Counterregulatory effect following administration of biosynthetic human proinsulin (BHPI) and human insulin (BHI) were compared during hypoglycemia standardized by means of a glucose controlled insulin infusion system (GCIIS). A total of 0.148 +/- 0.010 U/kg of BHPI had to be given by the GCIIS in order to obtain a minimal blood glucose (BG) of 26 +/- 2 mg/dl (means +/- SEM) at 43 +/- 2 min. In contrast, 0.083 +/- 0.004 U/kg of BHI were sufficient to produce a minimal BG of 21 +/- 1 mg/dl (n.s.) at 35 +/- 1 min. (P less than 0.005). Moreover, BHPI infusion resulted in prolonged hypoglycemia and delayed blood glucose recovery. On a molar basis, the acute BG lowering effect of BHPI was about 13% that of BHI (BHPI 3.94 +/- 0.27 vs. BHI 0.51 +/- 0.03 nmol/kg). Serum proinsulin after BHPI reached its maximum of 19.4 +/- 2 pmol/ml at 20 min. and still exceeded basal values markedly at the end of the test period at 240 min. Serum insulin peaked at 10 min. (162 +/- 47 microU/ml) and had already returned to basal values (7.5 +/- 1 microU/ml) after 45 min. No severe side effects were observed and there was no need for glucose administration, but clinical symptoms of hypoglycemia were more pronounced after BHPI. Compared to BHI, BHPI produced a higher cortisol peak (252 +/- 16 vs. 168 +/- 10 ng/ml), a more pronounced secretion of ACTH and GH as well as a stronger decline of serum potassium (3.20 +/- 0.06 vs. 3.58 +/- 0.08 mmol/l). Counterregulatory prolactin secretion did not differ significantly. Urinary epinephrine secretion following hypoglycemia after BHPI exceeded that after BHI (10.3 +/- 4.8 vs. 3.0 +/- 0.5 ng/120 min.). Serum lactate increase after BHPI was more prolonged (1.68 +/- 0.24 vs. 0.37 +/- 0.14 mmol/l at 120 min.). BHPI-induced inhibition of lipolysis, as determined by free fatty acid patterns, was delayed and less pronounced. Our results indicate that the observed more distinct glucose counterregulation is due to prolonged hypoglycemia rather than to any specific BHPI action on the hypothalamic-pituitary axis. We regard this as a consequence of the prolonged circulating and biological half-life. A preferential proinsulin action on the liver may play an additional role. Whether this "depot effect" may be beneficial in the treatment of diabetes mellitus remains to be established.

Adrenocorticotropic Hormone↗
PubMed1987

Metabolism of exogenous 4- and 2-hydroxyestradiol in the human male.

The metabolic fate of the isomeric catecholestrogens 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) was studied to elucidate possible differences in their metabolism as an explanation for their different bioactivities. Healthy young men (n = 3 each) were infused (90 min) with 4-OHE2 (60 micrograms/h) or 2-OHE2 (100 micrograms/h). The main metabolites were determined in plasma and urine before, during and after infusion. Unconjugated and conjugated steroids, the latter after hot acid hydrolysis, were subjected to chromatography on LH-20 columns and measured by specific RIAs. During the infusion 4-OHE2 reached significant plasma concentrations whereas 2-OHE2 was so rapidly metabolised that its plasma levels remained virtually undetectable in spite of a higher infusion rate. The metabolism of 4-OHE2 was dominated by direct conjugation, that of 2-OHE2 by methyl ether formation. These findings were corroborated by the urinary excretion rates: during the infusion and the first hours afterwards, 4-OHE2 was mainly excreted as 4-OHE2 and 4-hydroxyestrone, while 2-OHE2 was predominantly excreted as 2-hydroxyestradiol 2-methyl ether and 2-hydroxyestrone 2-methyl ether.

Adult↗
PubMed1987

[Diagnosis of thyroid function in premature infants in intensive care].

In 87 premature infants of an neonatal intensive care unit (gestational age 28-37 weeks) serum-T4, -fT4 and TSH were investigated on day 10, 20 and 30 and at term respectively, in addition to the usual TSH-screening (capillary specimen) on day 5. In 47 neonates (54%) T4 and fT4 were found to be low, including all infants under 30 weeks of gestational age and all ventilated infants. Screening TSH was not elevated but in some cases with iodine contamination. 12 of 13 infants in whom TRH-stimulation was performed showed significant response of TSH. We conclude that compromised thyroid function, common in prematures and infants under intensive care, is similar to the euthyroid sick syndrome in adults and does not require therapy. Replacement of thyroid hormone is only indicated in neonates with increased TSH.

Euthyroid Sick Syndromes↗
PubMed1986

Effect of various doses of catecholestrogens on uterine eosinophilia in the immature rat.

This paper describes the induction of uterine eosinophilia as well as of deep endometrial edema and increase of uterine wet weight in the immature rat by the catecholestrogens 2-OH-estradiol and 4-OH-estradiol. These effects are thought to be mediated by eosinophils via a specific eosinophil receptor system. 4-OH-estradiol was equipotent with estradiol, whereas the effect of 2-OH-estradiol was significantly weaker.

Animals↗
PubMed1986

Importance of A-ring substitution of estrogens for the physiology and pharmacology of reproduction.

Estrogens substituted in the ortho-position of the phenolic hydroxy-group with an additional hydroxy- or methoxy-group are quantitatively important estrogen metabolites; first isolated and identified from the urine of man and rodents have been demonstrated in blood and different organs, e.g. the pituitary and hypothalamus. The physiological importance of the preeminent representatives of this group, the 2- and 4-hydroxyestrogens, the so-called catecholestrogens, is still equivocal. For example, numerous in vivo investigations in rodents have demonstrated that gonadotrophin secretion is influenced by these catecholestrogens. However, depending on the position of the A-ring substituent, major potency differences have been observed. The significant discrepancies between the quantitative and qualitative effects of catecholestrogens in in vitro and in vivo experiments have been presented and explained on the basis of different receptor affinities and the pharmacokinetics of catecholestrogens. An array of A-ring-substituted steroid model substances has been tested with respect to the effects of 2- and/or 4-substitution on stimulation or blockade of the estrogenic potency.

Animals↗
PubMed1986

Ciprofloxacin: an overview of adverse experiences.

This review summarizes adverse reactions probably or possibly attributable to oral ciprofloxacin therapy in worldwide clinical experience involving over 6500 patients. In Europe and Japan the overall incidence of adverse reactions amongst patients receiving ciprofloxacin is reported to be 3.0% and 6.5%, respectively. An increased incidence (13.4%) has been reported from the U.S.A., possibly relating to the use of higher dosages. Very few reactions have necessitated withdrawal of treatment. The most common adverse effects involve the gastro-intestinal system (2-8% of patients treated) and usually comprise nausea, vomiting, diarrhoea and abdominal discomfort. CNS effects are seen in 1-4% of patients but are usually minor dizziness or mild headache only. Hypersensitivity reactions, most commonly skin rashes or pruritus, affect about 1% of patients. There is little evidence of significant haematological or biochemical toxicity, other than a few reports of transient neutropenia and the finding, in a minority of clinical studies, of equally transient, usually trivial and invariably reversible elevations of serum aminotransferases. Serious, ciprofloxacin-related toxicity has been observed in only three patients: one who developed pseudomembranous colitis, another who developed interstitial nephritis and a third who had a grand-mal convulsion during concomitant administration of theophylline. Ciprofloxacin appears to have an excellent safety profile.

Brain↗
PubMed1986

Short-term effects of oestradiol and 4-hydroxyoestradiol on gonadotrophin-releasing hormone induced luteinizing hormone secretion by rat pituitary cells in culture.

Dispersed pituitary cells from adult female rats were preincubated for different time periods (0-12 h) in the absence or presence of 10(-9)M oestradiol (E2) or 4-hydroxyoestradiol (4-OHE2). Then the media were changed and the cells incubated for 4 h with either vehicle, or E2, or 4-OHE2 and additionally with different concentrations (10(-11)-10(-7) M) of gonadotrophin-releasing hormone (GnRH). Treatment of pituitary cells with E2 for 4 h (i.e. no preincubation with E2) significantly decreased the LH-response to GnRH at concentrations greater than or equal to 10(-10) M of the decapeptide. During a transition time of approximately 10 h (i.e. in cultures preincubated with E2 or vehicle for 2, 4, 6 or 8 h and then coincubated with E2 or vehicle and GnRH for 4 h) no differences between E2- and vehicle-treated cultures were observed. After 14 and 16 h of E2-treatment (i.e. 10 or 12 h preincubation and 4 h coincubation with GnRH) the LH-responses to GnRH in these cultures were significantly higher than in the respective controls. A nearly identical reaction pattern was observed when 4-OHE2 was used instead of E2. In a second series of experiments dispersed rat pituitary cells were suspended in a carrier gel and continuously perifused with medium, using small chromatography columns. When these cells were exposed for 4 min to 10(-9) M GnRH at 60 or 48 min intervals, they reacted with reproducible pulsatile LH-discharges during at least 6 subsequent stimuli with the decapeptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Modulation of LH-secretion in ovariectomized ewes by constant infusions of oestradiol and 4-hydroxyoestradiol: effects of varying infusion times and of high oestrogen doses.

Ovariectomized ewes were infused for different times (2-24 h) during the breeding season (September to February) with oestradiol (E2, 2 micrograms/h) or the catecholoestrogen 4-hydroxyoestradiol (4-OHE2, 10 micrograms/h). At these infusion rates comparable plasma levels of E2 and 4-OHE2 were obtained when steady state was reached after 3 h (E2: 20 +/- 4 pg/ml; 4-OHE2: 22 +/- 3 pg/ml). When E2 was infused for at least 6 h, all animals had significant LH-surges, starting 14-16 h after the beginning of oestrogen treatment, even when E2 was infused for up to 24 h. 4-OHE2, however, had only to be infused for 4 h to induce significant LH-surges in all animals tested. When E2 was infused for 12 h at a rate of 100 micrograms/h, the LH-surges in these ewes were significantly lower than the LH-surges in the same animals treated for 12 h with E2 at a rate of 2 micrograms/h. These data indicate: Once E2 has been administered at a specific infusion rate for a critical time period of 6 h, LH-surges occur, no matter whether the E2-infusion is continued or stopped. For the catecholoestrogen 4-OHE2 this critical time period amounts only to 4 h, if comparable plasma levels of either oestrogen are achieved. This might hint at a prolonged intracellular action of 4-OHE2 as compared to E2. At extremely high infusion rates of E2 (100 micrograms/h for 12 h) the positive oestrogen effect is significantly impaired, a finding supporting the concept of a bell-shaped dose-response relationship between oestrogens and their positive effect on LH-secretion.

Animals↗
PubMed1986

Antibiotic use as an inducer of resistant urinary tract infections.

Urinary tract infection is second in frequency only to respiratory infection as an indication for antimicrobial chemotherapy. As a result, a significant proportion of both domiciliary and hospital patient populations are exposed to chemotherapy which, in turn, may act as a potent selection pressure for development of resistance mediated by intrinsic mechanisms or acquisition of R-plasmids or transposons. The widespread use of broad spectrum agents has encouraged the development of such resistance in enterobacteria, notably but not exclusively amongst the Klebsiella-Enterobacter-Serratia group, leading to the creation of patient reservoirs of multiply-antibiotic-resistant bacteria. Such situations occur frequently in urological units, amongst catheterised individuals receiving chemotherapy, and, via cross-infection, may rapidly spread to other units and other hospitals. The use of antibiotic combinations, such as co-trimoxazole, may not prevent such problems, which are however amenable to policies which restrict, either selectively or globally, antibiotic use. Such policies can be expected to control the spread of multiply-antibiotic-resistant infection.

Anti-Bacterial Agents↗
PubMed1985

Effects of short-term exposure to catecholestrogens on serum concentrations of gonadotrophins and metabolism of catecholestrogens in ovariectomized rats.

Equimolar amounts (36.8 nmol) of estradiol and the two catecholestrogens (CE's) 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) were injected subcutaneously to ovariectomized adult rats. Serum levels of both LH and FSH were determined at short-term intervals. Moreover, serum levels of the administered steroids and their main free and conjugated metabolites were monitored. Serum levels of the injected steroids reached peak values at different time points: estradiol between 60 and 240 min, CE's between 30 and 60 min. Peak height also differed significantly: with estradiol highest (1500 pg/ml), followed by 4-OHE2 (540 pg/ml) and then 2-OHE2 (135 pg/ml) (ratio 11:4:1). This mirrored the different MCR's of the steroids: CE's, especially 2-OHE2, were rapidly and extensively methylated and/or - to a lesser degree - conjugated. Estradiol remained mainly unchanged. LH-serum levels in steroid treated animals showed - irrespective of the steroid used - a uniform reaction pattern: they were significantly depressed 60 to 240 min after injection and - with the exception of estradiol treated rats - reached pretreatment levels again 480 min after injection. Ultra-short (15 min) effects were not observed. FSH serum levels in CE treated animals were not significantly altered, only E2 application led to a significant but small decrease in FSH levels 240 and 480 min after its injection. In conclusion, neither the effect of 4-OHE2 nor that of 2-OHE2 corresponded to the different MCR's or the MCR-corrected affinities for the classical estrogen receptor. A non-genomic mechanism may be responsible for this impaired effect of CE's.

Animals↗
PubMed1985

Comparative study of hormonal counter-regulation during GCIIS-guided insulin hypoglycemia tests using human insulin (recombinant DNA) and pork insulin.

Human insulin (BHI, recombinant DNA) and pork insulin (PI) were compared in 10 healthy volunteers. Using a glucose controlled insulin infusion system for the performance of the insulin hypoglycemia test (IHT), a comparable dosage of both insulins had to be infused (BHI 0.129 +/- 0.007 vs PI 0.115 +/- 0.01 U/kg; mean +/- SEM). Blood glucose slopes and nadirs did not differ significantly (BHI 30 +/- 2 vs PI 29 +/- 2 mg/dl). There was no difference in C-peptide inhibition (minimum for BHI 0.50 +/- 0.08 vs PI 0.42 +/- 0.08 micrograms/l). Maximum hormone responses were identical for ACTH (BHI 78.4 +/- 11.3 vs PI 76.0 +/- 8.7 pg/ml), cortisol (BHI 246 +/- 20 vs PI 252 +/- 15 ng/ml) and GH (BHI 43.8 +/- 7.3 vs PI 49.4 +/- 6.7 ng/ml). Peak levels of prolactin did not differ significantly (BHI 1,335 +/- 315 vs PI 1,766 +/- 614 microU/ml). The urinary excretion pattern of epinephrine in three 120 min periods before, during and after IHT was identical (before IHT: BHI 0.9 +/- 0.2 vs PI 0.6 +/- 0.1 micrograms/120 min; during IHT: BHI 12.6 +/- 2.2 vs PI 13.4 +/- 2.5 micrograms/120 min; after IHT: BHI 2.5 +/- 0.7 vs PI 3.7 +/- 1.3 micrograms/120 min). No differences in the minima of serum potassium levels were observed (BHI 3.38 +/- 0.04 vs PI 3.33 +/- 0.05 mmol/l). We conclude that the biological effects of human insulin and pork insulin are comparable. Our data do not support the assumption of a different hypothalamic handling of human insulin (recombinant DNA) and porcine insulin.

Adrenocorticotropic Hormone↗
PubMed1984

Large cell lymphomas. I. Differential diagnosis of centroblastic and B-immunoblastic subtypes by morphometry on histologic preparations.

Thirty-three large cell lymphomas, 18 centroblastic or large noncleaved follicle center cell lymphomas and 15 B-immunoblastic lymphomas, diagnosed by morphology and marker studies, were studied with morphometry. The following parameters were studied: nuclear and nucleolar area, nuclear shape, cytoplasm-to-nucleus ratio, number of nucleoli per nuclear cross section, location of the nucleolus within the nucleus as expressed by the relative nucleolar eccentricity (rNE), and the percentage of morphometrically defined immunoblasts. Mean values and standard deviations (SDs) were calculated and statistically analyzed. The two groups differed significantly in their nucleolar area (mean and SD), cytoplasm-to-nucleus ratio (mean), number of nucleoli per nuclear cross section (mean and SD), rNE (mean), and percentage of immunoblasts. Using nonlinear discriminant analysis, the possibility of classifying individual cases with the studied parameters was investigated. Twenty-nine cases were reliably classified (88%); three were classified correctly, but with less than a 95% certainty, and 1 case was misclassified. The results indicate a spectrum ranging from centroblastic to B-immunoblastic lymphoma. Transition forms occur and can be accurately defined with morphometry.

Adult↗
PubMed1984

Interactions of methylestrogens with cytoplasmic and nuclear estrogen receptors in rat pituitary gland, hypothalamus and uterus.

The in vitro affinities to cytoplasmic estrogen receptors of the methylestrogens 2-methylestradiol-17 beta, 4-methylestradiol-17 beta and 4-hydroxy-2-methylestradiol-17 beta, which are useful probes to test the biological importance of 2- or 4-hydroxylation of estradiol-17 beta (catecholestrogen formation), have been determined in hypothalamic, pituitary and uterine tissue of the ovariectomized rat. Moreover, the in vivo capacity of these compounds to translocate estrogen receptors into the cell nucleus of pituitary and uterine tissue has been studied. Methylestrogens exhibited estrogen receptor affinities which were not significantly different from the binding affinity of estradiol-17 beta. When given at a high dose (100 micrograms/animal) their nuclear translocation capacity was equal (4-methylestradiol-17 beta) or even higher (2-methylestradiol-17 beta) than that of estradiol-17 beta. However, at a low dose (5 micrograms/animal) 4-methylestradiol was completely ineffective in both the pituitary gland and the uterus, and 2-methylestradiol-17 beta was less potent than estradiol-17 beta in the pituitary gland.

Animals↗
PubMed1984

Insulin hypoglycaemia test guided by a glucose controlled insulin infusion system.

Insulin hypoglycaemia test (IHT) for assessment of hypothalamic-pituitary-adrenocortical (HPA) function in patients with pituitary tumours is usually performed by bolus injection of insulin, a procedure which includes the risk of overdosage and/or the need of repeated administration. This study describes that a glucose controlled insulin infusion system (GCIIS) permits to perform the IHT with standardized hypoglycaemia. Ten healthy volunteers and 10 patients with pituitary tumours were studied using the GCIIS (Biostator) on static control (Mode 1:1, BI 35, QI 10, RI 20, FI 300). Insulin administration was discontinued and the GCIIS used only for monitoring of blood glucose (BG), when BG had fallen below 40 mg/dl and initial clinical symptoms for hypoglycaemia were observed. In controls, the GCIIS guided IHT achieved a sufficient degree of hypoglycaemia (BG 27.6 +/- 2.0 mg/dl; mean +/- SEM) and physiological responses for GH (peak 49.4 +/- 6.7 ng/ml), Prl (peak 1766 +/- 614 microU/ml), ACTH (peak 76.0 +/- 8.7 pg/ml) and cortisol (peak 252 +/- 15 ng/ml). The total amount of insulin given was 0.115 +/- 0.012 U/kg. In the patients with pituitary tumours however, the required insulin dose varied markedly from 0.090 (pituitary insufficiency) to 0.340 U/kg (Cushing's syndrome). Minimum BG obtained was 32.5 +/- 1.9 mg/dl. Partial impairment of hypothalamic-pituitary function and, in particular, patients requiring exogenous cortisol supplementation during stress, could be identified. In conclusion, special advantages of the GCIIS-guided IHT are: Optimal insulin dosage with standardized hypoglycaemia due to automatic adjustment to the individual insulin sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗