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Biomedical subjects

W R Robertson

Publications and source records attributed to W R Robertson.

At least 55 records · Page 3Linked to original sources
PubMed1993

Efficacy of low dose purified FSH in ovulation induction following pituitary desensitization in polycystic ovarian syndrome.

OBJECTIVES: We evaluated the efficacy of ovulation induction using purified FSH in either low dose or conventional dosage in patients with polycystic ovarian syndrome. We assessed whether gonadotrophin measurement by radioimmunoassay or immunoradiometric assay is a better indicator of whether pituitary desensitization with a GnRH agonist (Zoladex) has occurred. DESIGN: Two different protocols were used. Pituitary desensitization was carried out with a GnRH agonist (Zoladex, ICI Pharmaceuticals UK). The patients were then randomized into one of two treatment groups. Conventional dose protocol: Patients commenced with a daily FSH (Metrodin, Serono Laboratories Ltd, UK) dose of 75 units for at least 7 days. The FSH dose was then increased, if necessary, based on ultrasound scans and plasma oestradiol (E2) levels in 75-unit increments. Low dose protocol: The same protocol was used except that the starting dose of FSH was 37.5 units daily with increments of 37.5 units. RESULTS: Low dose protocol (six patients, six cycles). There was a high incidence of multiple follicular development (10.3 +/- 5.6 (+/- SD) follicles, 5.0 +/- 3.8 follicles > 14 mm in diameter). Three cycles resulted in ovulation, one was anovulatory and two patients underwent gamete intrafallopian transfer due to multiple follicular development. Conventional dose protocol (seven patients, eight cycles). Again there was multiple follicular development (10.1 +/- 8.6 follicles, 2.0 +/- 2.3 > 14 mm). Three cycles were ovulatory, one anovulatory, three abandoned due to multiple follicular development and one underwent gamete intrafallopian transfer with the development of severe hyperstimulation necessitating steroid therapy. There was no difference between the two protocols in the number of days of FSH administration (low dose protocol 26 +/- 6.5, conventional dose protocol 23 +/- 8.1 days), the total number of units of FSH given per patient was 2844 +/- 1816 vs 2635 +/- 1726. The peak E2 level (pmol/l) during FSH treatment was 3193 +/- 662 vs 2389 +/- 3099 and the rate of increase in the FSH dose in ampoules of Metrodin per day was 0.058 +/- 0.03 vs 0.057 +/- 0.03. All patients were 'downregulated' (E2 < 70 pmol/l) prior to ovulation induction. However, gonadotrophin levels (IU/l) were 4.3 +/- 1.5 (LH) and 2.8 +/- 1.2 (FSH) by radioimmunoassay and LH was unchanged throughout FSH treatment whereas LH measured by immunoradiometric assay was < 1.0 IU/l prior to ovulation induction and remained so throughout. The mean LH radioimmunoassay to immunoradiometric assay ratio was 6.2 +/- 2.1. CONCLUSIONS: We conclude that regardless of the starting dose the use of pure FSH in patients with polycystic ovarian syndrome whose LH has been completely down regulated may be associated with multiple follicular development and a poor outcome. LH measured by radioimmunoassay is not a good indicator of whether pituitary densensitization has occurred but LH measured by immunoradiometric assay appears to be. These results strongly suggest that a basic minimum amount of LH is necessary for normal ovulatory development.

Adult↗
PubMed1993

Elevated serum immunoreactive inhibin levels in peripubertal boys with chronic renal failure. Cooperative Study Group on Pubertal Development in Chronic Renal Failure (CSPCRF).

OBJECTIVE: Boys with chronic renal failure have delayed progress through puberty and have raised gonadotrophin and low testosterone levels indicative of disturbed hypothalamo-pituitary-testicular function. Most studies into the mechanisms underlying the dysfunction have concentrated on the LH-Leydig cell interaction. However, it is now possible to probe the FSH-Sertoli cell axis by measuring plasma immunoreactive inhibin, which is a marker of Sertoli cell function. This study investigated the FSH-Sertoli cell (immunoreactive inhibin) axis in boys with chronic renal failure on conservative and dialysis treatment as they progressed through puberty. The effect of renal transplantation in chronic renal failure was also investigated. DESIGN: Blood was drawn at 15-minute intervals between 2000 and 0700 h from 51 boys with chronic renal failure at various stages of puberty. The samples were divided into two pools, corresponding to the hormone secretion in the first and second part of the night. Single blood samples were drawn from a group of normal boys between 0800 and 1000 h. PATIENTS: A total of 37 normal boys and 51 boys with chronic renal failure were examined immediately before and during puberty. Of a total of 80 pulse profiles taken in chronic renal failure, 36 were from transplanted and 44 from non-transplanted uraemic subjects. MEASUREMENTS: Immunoreactive inhibin, FSH and testosterone were measured using standard radioimmunoassays. The subjects were pooled into pubertal stages I, II/III and IV/V for analysis of hormone data. RESULTS: Early morning levels of immunoreactive inhibin like molecules (i-Inh) rose steadily with pubertal progression for all subject groups, those for boys with chronic renal failure being significantly elevated over normal boys from pubertal stage II/III onwards. Uraemic boys had higher levels than those who had been transplanted at all pubertal stages (P < 0.05). Early morning levels of FSH were significantly higher in uraemic patients with pubertal stages IV/V compared to our normal boys. There were no differences in i-Inh levels in plasma pooled from the samples taken between 2000 and 0115 h and 0130 and 0700 h for either treatment group at any stage of puberty. Testosterone levels rose in the second part of the profile from pubertal stages II/III onwards for both treatment groups. The proportional increase of testosterone was lower by mid puberty in uraemic than in transplanted children (percentage increases of 92 +/- 29 and 569 +/- 190 respectively, mean +/- SEM). i-Inh failed to correlate with FSH at any Tanner stage or for any subject group. CONCLUSION: Peripubertal boys with chronic renal failure have highly elevated serum immunoreactive inhibin and FSH levels which are partially reduced by renal transplantation. There was no evidence of any relationship between i-Inh and FSH secretion in either normal boys or in uraemic or transplanted boys with the exception of a positive correlation in late pubertal patients after transplantation. Finally, despite problems associated with the current immunoassay for inhibin, this assay may still prove to be a useful marker of Sertoli cell function in testicular pathology.

Adolescent↗
PubMed1993

Adrenocorticotropic hormone receptor-blocking immunoglobulins in serum from patients with Addison's disease: a reexamination.

The presence of antibodies inhibitory to ACTH-stimulated cortisol secretion was investigated in patients with Addison's disease. In preliminary experiments, immunoglobulin G (IgG) samples from patients with Addison's disease and control subjects were prepared using diethylaminoethyl-cellulose ion exchange chromatography. Twelve of 29 Addison's IgGs and 1 of 3 control IgGs inhibited ACTH-stimulated cortisol secretion in an in vitro guinea pig adrenal cell bioassay. All but 1 of the samples that inhibited ACTH-stimulated cortisol secretion also inhibited dibutyryl cAMP-stimulated steroidogenesis. IgGs purified by protein-G immunoaffinity were similarly screened for inhibition of ACTH-stimulated cortisol secretion; samples from 5 controls and 5 patients with Graves' disease were without effect, and IgGs from only 2 of 25 patients with Addison's disease decreased ACTH bioactivity (by < 12%). The effects of the IgGs on ACTH bioactivity in vitro were not concentration dependent. Our results suggest that Addison's disease is not caused by circulating antibodies to the ACTH receptor. The inhibitory effects seen with IgG prepared by diethylaminoethyl ion exchange chromatography were most likely attributable to the effects of non-IgG components in the preparations.

Addison Disease↗
PubMed1993

Hypothalamo-pituitary-adrenal axis in uraemia: evidence for primary adrenal dysfunction?

To study hypothalamo-pituitary-adrenal axis disturbances in chronic renal failure, we administered corticotrophin-releasing hormone to patients undergoing haemodialysis and CAPD and to normal controls. Cortisol, ACTH, and ACTH precursors were measured before and after corticotrophin-releasing hormone using sensitive and specific two-site assays. Baseline ACTH and cortisol were similar in all groups. Peak values occurred at 30 min (ACTH) and between 30 and 60 min (cortisol). The cortisol (but not the ACTH) responses were significantly reduced in patients with renal failure (P < 0.05). ACTH precursors did not change from baseline following corticotrophin-releasing hormone but were significantly elevated in patients with renal failure compared to controls (P < 0.01). The reduced cortisol response to corticotrophin-releasing hormone may reflect a primary defect of adrenal function in renal failure.

Adolescent↗
PubMed1992

Expression of an oestrogen receptor-related antigen in human endometrium: a microphotometric study.

The expression of an oestrogen receptor-related antigen has been measured by microspectrophotometry in the glandular epithelium and stroma of tissue sections from endometrial biopsies of women administered exogenous replacement of sex steroids because of premature ovarian failure. We have demonstrated that previously dormant endometrium is capable of expressing an antigen related to oestrogen receptors and that its distribution is influenced by the sex steroid environment. Immunohistochemical staining was more intense (P less than 0.001) in the glandular compared to the stromal cells in tissue exposed solely to oestradiol. With the administration of progesterone, the stromal staining intensity increased (P less than 0.0001) and that of the glandular staining decreased (P less than 0.0001). No assumption, however, has been made to infer that colour is stoichiometrically related to the concentration of antigen present. Further validation of immunohistochemical procedures is required because histological localization and measurement of immunohistochemical staining may be straightforward, but its relationship to antigen concentration remains unproven.

Antibodies, Monoclonal↗
PubMed1992

Immunoreactive inhibin levels during ovarian stimulation may predict granulosa cell maturity.

OBJECTIVE: The aim of the study was to assess whether the immunoreactive inhibin response to ovarian stimulation in polycystic ovarian syndrome was of predictive value for the outcome of ovulation induction. DESIGN: Daily injections of purified FSH (Metrodin, Serono Laboratories, UK) were administered for the purpose of inducing development and ovulation of a single follicle. PATIENTS: All patients had anovulatory infertility secondary to polycystic ovarian syndrome and were resistant to clomiphene citrate. MEASUREMENTS: Alternate day serum samples were obtained for measurement of gonadotrophins, sex steroids and inhibin by radioimmunoassay. Alternate day ovarian ultrasound scans were carried out to monitor follicular development. RESULTS: There was a high incidence of multiple follicular development (MFD) (10.2 +/- 7.1 (standard deviation) follicles). There was a close relationship between the number of follicles on the day of the ovulatory trigger and serum oestradiol (E2) levels (R = 0.97, P < 0.001). This relationship was not seen with serum immunoreactive inhibin levels (R = 0.31). The cycles were divided into two groups depending whether there was or was not MFD (more than five follicles > 7 mm in diameter on day of hCG administration). The MFD group had 15.6 +/- 8.5 follicles and the non-MFD group 3.2 +/- 1.6 follicles. There was no difference in the circulating E2 concentration (pmol/l) per follicle between the two groups (non-MFD cycles, n = 6,345 +/- 28.9; MFD cycles, n = 8, 308 +/- 40.29). However, the immunoreactive inhibin concentration (U/ml) per follicle was lower, P < 0.001, in the MFD group (4.3 +/- 1.6 vs 6.9 +/- 0.5). The maximum and mean follicle diameter were lower, P < 0.01, in the MFD group (maximum follicle size 16.5 +/- 3.9 vs 21.2 +/- 1.5 mm, mean follicle size 11.5 +/- 2 vs 14.9 +/- 2.3). When individual cycles were examined E2 and immunoreactive inhibin secretion rose in parallel in cycles with less than five follicles with a rapid rise occurring when the follicles reached about 12 mm in diameter. In cycles where there was MFD there was a disparity between E2 and immunoreactive inhibin secretion with E2 levels rising 4.3 +/- 1.4 days before immunoreactive inhibin levels. CONCLUSION: These data suggest that in cycles where there are multiple small follicles, E2 secretion is maintained whereas immunoreactive inhibin secretion is substantially lower. Thus, in view of the disparity between E2 and immunoreactive inhibin secretion evident in the MFD group, measurement of immunoreactive serum inhibin concentration may be a better indicator of granulosa cell maturity. Immunoreactive inhibin secretion may occur only from healthy mature follicles.

Estradiol↗
PubMed1992

Human chorionic gonadotrophin contributes to the bioactivity of Pergonal.

OBJECTIVE: We examined batch variation in the LH-like bioactive content of Pergonal and determined whether hCG contributes to this. DESIGN: Random selection of three batches of Pergonal, consisting of three ampoules in each batch. MEASUREMENTS: The LH content in each ampoule was determined by radioimmunoassay (R-LH), immunoradiometric assay (I-LH) and in vitro Leydig cell bioassay (B-LH) using the urinary hMG International Standard 70/45. Human chorionic gonadotrophin was determined by immunoradiometric assay (I-hCG) using the hCG IRP 75/537. The isohormone content of each batch was examined by chromatofocussing over the range pH 4.5-7.0 and the fractions collected were assayed for LH and hCG content. The variability in potency between batches was assessed by single factor analysis of variance. RESULTS: The gonadotrophin content of each batch (IU/ampoule, mean +/- SEM, n = 3 ampoules) was R-LH (40.9 +/- 0.5, 40.8 +/- 0.2, 39.3 +/- 0.7, P > 0.15), I-LH (39.0 +/- 1.5, 28.3 +/- 0.8, 36.9 +/- 3.3, P < 0.001), B-LH (27.3 +/- 0.3, 12.0 +/- 0.9, 19.3 +/- 0.9, P < 0.001) and I-hCG (16.4 +/- 0.7, 11.7 +/- 0.2, 10.5 +/- 0.5, P < 0.001). The chromatofocussing recoveries below pH 5.5 expressed as a percentage of the total amount of analyte eluted from the column and collated for all three batches of Pergonal were (mean % +/- SD, n = 3 batches) R-LH (58.4 +/- 4.0), I-LH (41.3 +/- 7.5), B-LH (81.4 +/- 2.8) and I-hCG (87.8 +/- 3.7). CONCLUSIONS: There was significant batch variation in the I-LH, B-LH and I-hCG (P < 0.001) but not the R-LH (P > 0.15) content of Pergonal. More than 80% of the total B-LH recovery chromatofocussed below pH 5.5 and corresponded to the region of highest I-hCG (> 87%) and lowest I-LH (< 42%) recovery. This was highly suggestive of hCG contributing to the LH-like bioactivity of Pergonal.

Chorionic Gonadotropin↗
PubMed1992

An investigation of LH pulsatility in burned men by bioassay and radioimmunoassay.

LH pulsatility studies were performed in six burned patients by removing blood samples at 10 min intervals over a 6 h period. All samples were assayed for LH by bioassay (B-LH), LH by radioimmunoassay (I-LH) and testosterone. Mean serum testosterone concentrations of the burned patients were low (6.7 +/- 1.6 nmol/l). I-LH levels were lower than B-LH in all samples. Frequency of bioactive or immunoreactive pulses as well as mean B-LH and I-LH concentrations were similar to previously published data from normal men examined in the same laboratory. The mean biological activity of LH (expressed as the ratio of B-LH to I-LH, the B:I ratio) was lower in burned subjects (1.9 +/- 0.1) than previously reported in normal men. The B:I ratios of burned men were lower (p less than 0.01) at pulse peaks than at nadirs (1.8 +/- 0.1 vs 2.0 +/- 0.1) and an increase in serum testosterone concentration did not follow an LH peak. Serum testosterone concentrations did not cross-correlate with B-LH or I-LH. This contrasts with the findings in normal subjects where the B:I ratios have been found to be higher at pulse peaks than at nadirs and an increase in serum testosterone concentration follows a pulse peak and serum testosterone cross-correlates with B-LH and I-LH. LH secreted in a pulse peak in normal men may contain a particularly biologically potent form of the molecule but this may not be the case in burned men.

Adult↗
PubMed1992

Microheterogeneity of thyroid-stimulating hormone from the pituitaries of euthyroid, hypothyroid and hyperthyroid rats.

The microheterogeneity of pituitary thyroid-stimulating hormone (TSH) is dependent on variations in the hormone's carbohydrate moieties. In this study, changes in the pattern of heterogeneity have been assessed by chromatofocusing, which separates the isospecies on the basis of their isoelectric points (pI). Rats (n = 6 per group) were either untreated or rendered hypo- or hyperthyroid by including in the drinking water either propylthiouracil (0.05% for 8 weeks) or thyroxine (T4; 4 mg/l for 6 weeks) before they were killed at 16 weeks. On autopsy, serum TSH and total T4 were (means +/- S.E.M.): 2 +/- 0.3 micrograms TSH/l and 64 +/- 5 nmol T4/l (control); < 1 microgram TSH/l and 133 +/- 6 nmol T4/l (hyperthyroid); 58 +/- 6 micrograms TSH/l and 32 +/- 6 nmol T4/l (hypothyroid). The pituitaries were individually homogenized and the TSH isoforms separated by chromatofocusing over a pH range of 7-4. Fractions were assayed for TSH by radioimmunoassay. TSH from the control group was distributed into seven major peaks with pI values of (means +/- S.E.M., n = 6) 6.9 +/- 0.1, 6.6 +/- 0.1, 6.2 +/- 0.1, 5.8 +/- 0.1, 5.5 +/- 0.1, 5.2 +/- 0.1 and 4.8 +/- 0.1; 7 +/- 3% of the TSH had a pI of < 4.0. Six peaks of TSH were conserved in the hypothyroid group (with pI values of 6.8 +/- 0.1, 6.5 +/- 0.1, 6.2 +/- 0.1, 5.8 +/- 0.1, 5.4 +/- 0.1 and 5.2 +/- 0.1), and 11 +/- 4% of the hormone had a pI of < 4.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Different isoforms of human pituitary thyroid-stimulating hormone have different relative biological activities.

The relationship between the immunological and biological activities of thyroid-stimulating hormone (TSH) isoforms present in the three human pituitary preparations 68/38 (1st IRP), 80/558 (2nd IRP) and 63/14 (MRC Research Standard A) was investigated. The isoforms were separated by chromatofocusing. Six peaks of immunoactivity were detected in 80/558, with pI values (means +/- S.E.M.) of 6.6 +/- 0.1, 6.2 +/- 0.1, 5.9 +/- 0.1, 5.5 +/- 0.1, 5.2 +/- 0.1 and 4.9 +/- 0.1. Four peaks, with pI values of 6.8 +/- 0.1, 5.9 +/- 0.1, 5.5 +/- 0.1 and 5.2 +/- 0.1, were observed for 68/38. Standard 63/14 had five peaks, with pI values of 6.9 +/- 0.1, 6.4 +/- 0.1, 5.9 +/- 0.1, 5.4 +/- 0.1 and 4.9 +/- 0.1. For each standard, six fractions around the peak areas and at the top and bottom of the gradient were pooled and microconcentrated to < 1.0 ml. Microconcentrated TSH samples were assayed in three TSH bioassays based upon FRTL-5 thyroid cells, utilizing cyclic AMP accumulation, iodide and thymidine uptake as end-points and standard 80/558 as reference preparation. The more acidic forms of TSH showed a higher biological:immunological (B:I) ratio for cyclic AMP accumulation with, for example, 63/14 having a maximum of 3.7 (pI 4.9) and a minimum of < 0.7 (pI 6.9). In contrast, the maximum and minimum B:I ratios for iodide uptake for 63/14 were 3.8 (pI 6.9) and < 0.8 (pI 4.6), and for thymidine uptake, maximum and minimum ratios were 7.2 (pI 6.9) and 1.1 (pI 4.6) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Assay↗
PubMed1992

Identification of exchange mechanisms for the regulation of intracellular pH in rat thyroid FRTL-5 cells.

pH is maintained in cells by plasma membrane exchange mechanisms. In the absence of HCO3- ions, FRTL-5 cells regulate intracellular pH (pHi) by an Na+/H+ antiport but HCO3(-)-dependent exchangers cannot operate. We have investigated pHi regulation (by microfluorimetry and the pH sensitive dye 2',7'-bis(2-carboxyethyl)-5(6')-carboxyfluorescein) in small groups (five to six cells) of FRTL-5 thyroid cell monolayers held in Krebs-Ringer buffer (pH 7.4) with or without HCO3- ions. The exchangers were investigated with inhibitors (amiloride or its derivative dimethylamiloride for the Na+/H+ antiporter and the stilbene derivative disodium 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) for HCO3(-)-dependent mechanisms), ionic substitution and by NH4+/NH3 (10 mM) acid loading. Basal pHi was lower in the presence (7.3 +/- 0.058, mean +/- S.D., n = 14) than in the absence (7.59 +/- 0.078, n = 10) of HCO3- ions. In HCO3(-)-free media, cells recovered from acid load by 0.34 +/- 0.04 pH units in the first 2 min and finally reached a pHi of 7.35 +/- 0.06. This recovery was Na(+)-dependent and blocked by dimethylamiloride during the 15 min following intracellular acidification. In HCO3(-)-containing media, cells recovered from an acid load at a similar rate, but reached 99 +/- 10% (n = 9) of the baseline pH; this recovery was also dependent on Na+ ions. Moreover, although dimethylamiloride and DIDS reduced the rate of recovery to 0.06 +/- 0.02 and 0.18 +/- 0.04 pH units respectively during the 2-min period, the cells returned to the basal pHi within 15 min.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

The effects of hypo- and hyperthyroidism on fibre composition and mitochondrial enzyme activities in rat skeletal muscle.

Hypo- and hyperthyroidism have been associated with changes in the activities of mitochondrial enzymes in homogenates of skeletal muscles, but it is unclear whether such changes were due to changes in single fibre enzyme activities or to previously documented changes in relative numbers of fibres. In this study the activities of the mitochondrial enzymes alpha-glycerol phosphate dehydrogenase (m-alpha GPDH) and succinate dehydrogenase (SDH) were measured in single fibres of the soleus and gastrocnemius muscles of the rat by cytochemical assays. In the soleus muscles of hypothyroid animals there was a decrease in the mean percentage (+/- S.D.) of type II fibres from 8.0 +/- 6.0 to 0.8 +/- 1.9% (P less than 0.05) and decreases in SDH activities in all fibre types (P less than 0.005). In the gastrocnemius muscles of these animals there were no changes in fibre composition but type IIB fibres had reduced (P less than 0.05) m-alpha GPDH activities. In the hyperthyroid animals, in which body weight had increased relative to the euthyroid animals, there were increases in the percentages of type IC and type II fibres in the soleus from 4.3 +/- 1.7 to 13.1 +/- 9.0% (P less than 0.05) and from 9.6 +/- 7.2 to 33.4 +/- 9.6% (P less than 0.005) respectively and an increase in the percentage of type IIA fibres in the gastrocnemius from 92.9 +/- 2.3 to 97.0 +/- 2.9% (P less than 0.05). However, there were no increases in single fibre mitochondrial enzyme activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Long-term effects of thyroid stimulating hormone and insulin on intracellular pH in FRTL-5 cells.

We have studied the chronic effects of TSH (100 microU/ml) and insulin (10 micrograms/ml) on intracellular pH (pH(i)) in FRTL-5 cells using the pH sensitive probe 2'7-bis (2-carboxyethyl-5'-6') carboxyfluorescein. FRTL-5 cells were cultured on Petri dishes either in the presence of 4H, ie. Coons F-12 containing cortisol (10 nM), transferrin (0.5 microgram/ml), glycyl-histidyl lysine acetate (10 ng/ml) and somatostatin (10 micrograms/ml), or with 4H + insulin (5H), 4H + TSH, or 4H + TSH + insulin (6H). pH(i) was measured in small groups of cells by microspectrofluorimetry both in the presence and absence of bicarbonate ions after cells had been deprived of serum for at least a day. In the absence of TSH, insulin and bicarbonate ions, pH(i) was 7.26 +/- 0.18 (mean +/- SD, n = 49) rising to 7.89 +/- 0.09 (n = 59) and 7.43 +/- 0.1 (n = 55) in the presence of TSH (4H + TSH) and insulin (5H) respectively. Addition of both insulin and TSH (6H) resulted in a pH(i) of 7.75 +/- 0.09 (n = 40). In the absence of TSH and insulin, but the presence of bicarbonate ions, pH(i) was 7.29 +/- 0.12 (mean +/- SD n = 47) rising to 7.72 +/- 0.07 (n = 59) in 4H + TSH and 7.48 +/- 0.08 (n = 60) in 5H. pH(i) in the presence of both TSH and insulin was 7.81 +/- 0.03 (n = 60). In conclusion, both insulin and TSH caused an intracellular alkalinization, TSH markedly so, even in the presence of bicarbonate ions.

Animals↗
PubMed1992

Intracellular pH regulation in human thyrocytes: evidence of both Na+/H+ exchange and Na(+)-dependent Cl-/HCO3- exchange.

The present study was undertaken to investigate the regulation of intracellular pH in human thyroid epithelial cells and to characterize the kinetics of the acid-extruding processes operating in the absence and presence of HCO3-, Na+ and Cl-. A dynamic technique of dual excitation microfluorimetry and the pH-sensitive fluorescent probe 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein was employed. The intracellular pH was 7.01 +/- 0.27 (n = 29) and 6.94 +/- 0.25 (n = 54) in the absence and presence of HCO3- respectively. Both in the absence and presence of HCO3-, the recovery from intracellular acid loads was not only due to an Na+/H+ exchange, but also to an Na(+)-dependent HCO3-/Cl- exchange. In alkaline conditions caused by NH4Cl pulsing, an HCO3-/Cl- exchange was also found. The cells in HCO3- responded with a wide range of maximal hydrogen efflux rates in experiments where cells were either pretreated with 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid or incubated with amiloride. The heterogeneity might be due to subpopulations of thyrocytes in different metabolic states or at different points in the cell cycle. It is concluded that recovery from intracellular acidification in human thyroid cells is due to both Na+/H+ exchange and Na(+)-dependent Cl-/HCO3- exchange even in nominally HCO3(-)-free conditions, and that recovery from intracellular alkalinization is due to a Cl-/HCO3- exchange which needs to be characterized further.

Bicarbonates↗
PubMed1991

Pulsatile immunoreactive and bioactive luteinizing hormone secretion in adolescents with chronic renal failure. The Cooperative Study Group on Pubertal Development in Chronic Renal Failure (CSPCRF).

Delayed or arrested pubertal development is common in children with chronic renal failure (CRF). Normal puberty is initiated by the onset of episodic nocturnal secretion of luteinizing hormone (LH) containing an increasing proportion of bioactive hormone. To test the functional integrity of the hypothalamo-pituitary axis in CRF we measured immunoreactive (i-LH) and bioactive (bio-LH) plasma LH concentrations at 15-min intervals from 2000 to 0700 hours in 65 pubertal patients aged 10-23 years [46 boys/19 girls; 20 on conservative treatment (CT), 13 on dialysis (D), 32 with transplants (TP)]. i-LH was determined by radio-immunoassay and bio-LH by a mouse Leydig cell assay. Peak detection was performed by the cluster analysis computer programme. The mean (+/- SD) number of i-LH (in both sexes) and bio-LH pulses (in boys) per profile, and the mean peak area of i-LH (in both sexes) and bio-LH (in girls) were higher in TP than in CT or D patients. The ratio of bio-LH to i-LH increased during puberty in CT (G1 vs G4/5, 0.3 +/- 0.5 vs 1.8 +/- 0.,4) and TP (0.6 +/- 0.7 vs 1.8 +/- 0.7) but remained low in male D patients (0.4 +/- 0.7 vs 1.1 +/- 0.8). The ratios were subnormal, however, even in mature TP patients compared with healthy adults. The bio-LH/i-LH ratio and the bio-LH peak area best predicted integrated nocturnal testosterone concentrations in TP but not in uraemic male patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Pattern of secretion of bioactive and immunoreactive gonadotrophins in normal pubertal children.

OBJECTIVE: The aim was to investigate the relationship between the nocturnal pulsatile secretory patterns of immunoreactive and bioactive luteinizing hormone in normal children at various stages of puberty. DESIGN: Blood samples were taken at 15-minute intervals from 2000 hours to 0800 hours. Pubertal stage was assessed by the method of Tanner (1962). PATIENTS: Thirty-four healthy siblings (17 males, 17 females) of diabetic children were recruited (median age 13.1, range 9.1-20.9 years). They were of normal height, non-obese, and covered the range of puberty. MEASUREMENTS: Follicle stimulating and luteinizing hormone levels were measured by radioimmunoassay in all 34 subjects; bioactive LH (B-LH) was assayed in a subgroup of 13 subjects selected to encompass the range of normal puberty. Oestradiol (girls) and testosterone (boys) were also measured at hourly intervals. RESULTS: Immunoreactive luteinizing and follicle stimulating hormone concentrations showed a progressive rise during puberty in both sexes. FSH concentrations were significantly higher in females than in males at all stages of puberty. Overnight mean bioactive luteinizing hormone concentrations were higher than immunoreactive luteinizing hormone levels in all the girls studied (n = 7). Although the number of bioactive luteinizing hormone pulses (31) was greater than immunoreactive pulses (27), the profiles were generally very similar. In the early pubertal girls an increase in the bioactive: immunoreactive ratio was observed during the middle of the night with the onset of pulsatility. Oestrogen was detected in the girls in breast stage 4-5 but not in two of the early pubertal girls, despite pulses of immunoreactive and bioactive luteinizing hormone. The boys had higher mean bioactive than immunoreactive luteinizing hormone levels and overall bioactive and immunoreactive luteinizing hormone and testosterone concentrations increased with puberty stage. Concordance between bioactive and immunoreactive hormone pulses was good although more immunoreactive pulses (16) were seen than bioactive pulses (14). As in the girls, an increase in the bioactive: immunoreactive ratio was observed in the middle of the night with the onset of pulsatility at genital stage 2 but, in contrast to the oestrogen data in the girls, testosterone secretion always followed luteinizing hormone pulsatility overnight. CONCLUSION: We conclude that mean overnight immunoreactive luteinizing and follicle stimulating hormone concentrations increase during puberty in both sexes. Bioactive luteinizing hormone levels are two to three times higher than immunoreactive luteinizing hormone in both sexes, but there is very little discordance between immunoreactive and bioactive luteinizing hormone pulsatility. The bioactive: immunoreactive ratio increases with the occurrence of pulsatility overnight in early pubertal children. The relationship between these changes in bioactive and immunoreactive luteinizing hormone and sex steroids is clearest in boys where the nocturnal testosterone rise always follows pulsatile LH secretion.

Adolescent↗
PubMed1991

Follicle-stimulating hormone-dependent estrogen secretion by rat Sertoli cells in vitro: modulation by calcium.

We have investigated the role of Ca2+ in the control of FSH-induced estradiol secretion by Sertoli cells isolated from 8-10 days old rats. Exogenous Ca2+ (4-8 mmol/l) inhibited FSH-stimulated E2 secretion such that, with 8 mmol/l Ca2+ and FSH (8 IU/l) E2 secretion decreased from 2091 +/- 322 to 1480 +/- 84 pmol/l (p less than 0.002), whilst chelation of Ca2+ in the culture medium with EGTA (3 mmol/l) increased E2 secretion from 360 +/- 45 to 1242 +/- 133 pmol/l) in the absence of FSH. Further, EGTA (3 mmol/l) markedly potentiated FSH (8 IU/l), forskolin (1 mumol/l) and dibutyryl cAMP (1 mmol/l)-stimulated E2 secretion. Addition of the Ca2+ ionophores, ionomycin (2-5 mumol/l) and A23187 (2 mumol/l), inhibited FSH (8 IU/l)-stimulated E2 secretion by greater than 80%. The effect of ionomycin was totally reversible, whereas that of A23187 was irreversible. Ionomycin (5 mumol/l) had no effect on EGTA-induced E2 secretion in the absence of FSH, but reduced EGTA-provoked E2 secretion by 59% in the presence of FSH (8 IU/l). Similarly, forskolin- and dibutyryl cAMP-provoked E2 production was inhibited 46-50% by ionomycin (5 mumol/l). We conclude that FSH-induced E2 secretion from immature rat Sertoli cells is modulated by intra- and extracellular Ca2+.

Animals↗