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Biomedical subjects

D A Heath

Publications and source records attributed to D A Heath.

At least 73 records · Page 4Linked to original sources
PubMed1991

Inhibin production in vitro by granulosa cells from Booroola ewes which were either homozygous or non-carriers of a fecundity gene influencing their ovulation rate.

The production of inhibin by granulosa cells was studied in vitro using cells from follicles of various sizes and health. Follicles were recovered on Days 10-13 of the oestrous cycle, from Booroola x Romney ewes which were homozygous (FF) carriers or non-carriers (++) of the fecundity (F) gene. Inhibin was measured using a bioassay based on the suppression of follicle-stimulating hormone (FSH) output by cultured pituitary cells from ovariectomized Romney ewes and, in some instances, for comparative purposes, by radioimmunoassay also. Geometric mean inhibin production by granulosa cells from nonatretic follicles increased with increasing follicle diameter, during the first 24 h of culture, for both genotypes. The geometric mean production of inhibin by cells from nonatretic 3-4.5 mm diameter FF follicles (the largest follicles found in FF ewes), was significantly higher (P less than 0.05) than that by cells from non-atretic 3-4.5 mm diameter ++ follicles, but similar to that of cells from non-atretic greater than or equal to 5 mm diameter ++ follicles. The production of oestradiol-17 beta by cells cultured in the presence of testosterone (1 microgram/ml) followed a pattern similar to cellular inhibin production. There was a positive linear correlation between inhibin and oestradiol-17 beta production during the first 24 h of culture, for both genotypes. In addition to acting as a substrate for oestradiol-17 beta synthesis, testosterone generally had a slight, stimulatory effect on inhibin production.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Expression of parathyroid hormone-related protein mRNA in the rat before birth: demonstration by hybridization histochemistry.

The ontogeny of parathyroid hormone (PTH) and PTH-related protein (PTHrP) gene expression was studied by hybridization histochemistry in the rat at various stages between implantation and full term. PTHrP mRNA was demonstrable in the early postimplantation trophoblastic giant cells but disappeared from this site before 13.5 days. Localized gene expression, detectable by the in-situ technique, began between 12.5 and 15.5 days in embryonic tissues. The distribution of gene expression suggests that PTHrP may be concerned with the process of implantation. Its widespread, yet clearly localized, distribution in embryonic and fetal tissues is consistent with a paracrine or autocrine function which may relate to the transforming growth factor-beta family of growth factors. PTH expression occurred solely in the parathyroid and was detectable in the fetal parathyroid at 13.5 days of gestation.

Animals↗
PubMed1991

Expression of parathyroid hormone-related protein in abnormal human parathyroids.

The expression of parathyroid hormone-related protein (PTHrP) in abnormal human parathyroids was investigated. Northern blot analysis of RNA extracted from human benign parathyroid adenomata (n = 4) revealed multiple PTHrP mRNA species ranging in size from 1.8 to 4 kb. The relative abundance of PTHrP mRNA expressed in two of the adenomata was similar to that of a tumour (DAF) associated with humoral hypercalcaemia of malignancy, whereas PTHrP mRNA was of low abundance in a third and was undetectable in the fourth. PTHrP-like immunoreactivity was detected in extracts of abnormal parathyroid tissue (benign adenoma (n = 7), hyperplasia (n = 5) and parathyroid carcinoma (n = 2] using a sensitive specific two-site immunoradiometric assay for human (h) PTHrP(1-86) and a radioimmunoassay for hPTHrP(1-34). Ratios of hPTHrP(1-86)- and hPTHrP(1-34)-like immunoreactivities relative to hPTH(1-84)-like immunoreactivity in the parathyroid tissue extracts were, on average, less than 1%. PTHrP bioactivity in the extracts could not be distinguished from that of PTH, by an osteosarcoma cell bioassay. We conclude that, despite reports of over-expression of PTHrP mRNA in parathyroid adenomata, the potential contribution of PTHrP to the total PTH-like activity of adenomata and other abnormal parathyroid tissue may be insignificant relative to PTH.

Adenoma↗
PubMed1991

Immunoreactivity of plasma parathyrin-related peptide: three region-specific radioimmunoassays and a two-site immunoradiometric assay compared.

We measured parathyrin (parathyroid hormone)-related peptide (PTHRP) in plasma by three region-specific RIAs and compared them with an established two-site immunoradiometric assay (IRMA) of PTHRP1-86 in samples from control subjects and from patients with primary hyperparathyroidism (PH) and humoral hypercalcemia of malignancy (HHM). The two direct RIAs of PTHRP1-34 and PTHRP37-67 were specific for regions 9-18 and 52-61, respectively. In the extraction RIA of PTHRP1-34 we used an affinity gel containing a monoclonal antibody specific for the 17-27 sequence; cross-reacting PTHRP species eluted from the gel were assayed by the RIA of PTHRP1-34. PTHRP1-86 plasma concentrations by IRMA were less than 0.23 pmol/L in control subjects and patients with PH, and were significantly increased in patients with HHM (mean 6.1 pmol/L, P less than 0.001). In contrast, plasma PTHRP1-34 concentrations were not significantly different in the three groups; in HHM patients, the mean was 190 pmol/L. Plasma PTHRP37-67 concentrations were similar in control and PH groups and, although significantly increased in HHM patients (mean 440 pmol/L, P less than 0.002), showed poor diagnostic discrimination. PTHRP1-34 concentrations after affinity extraction of plasma were also significantly higher in HHM patients (mean 10.7 pmol/L, P less than 0.001), but showed incomplete diagnostic discrimination. We conclude that the diagnostic utility of the direct RIAs for quantifying PTHRP is markedly inferior to the IRMA of PTHRP1-86.

Humans↗
PubMed1991

Development and validation of an immunoradiometric assay of parathyrin-related protein in unextracted plasma.

This two-site immunoradiometric assay for human parathyrin-related protein 1-86 (PTHRP1-86) in plasma uses a mouse monoclonal antibody to PTHRP1-34 coupled to cellulose particles for immunoextraction of N-terminal immunoreactivity, and a rabbit antiserum to PTHRP37-67 that is indirectly labeled with 125I-labeled PTHRP37-67 for quantifying the bound analyte. The detection limit of the assay is 0.23 pmol/L, corresponding to 0.4 pg (0.04 fmol) per tube, for a sample volume of 200 microL. Recovery of PTHRP1-86 added to serum is essentially quantitative, and within- and between-batch precision is 4.4% and 11.1%, respectively. PTH1-84, PTHRP18-34, PTHRP9-34, PTHRP1-34, and PTHRP37-67 do not cross-react in the assay at concentrations up to 2 nmol/L. Plasma concentrations of PTHRP1-86 were below or close to the detection limit of the assay in normal subjects and in patients with primary hyperparathyroidism, hypoparathyroidism, chronic renal failure, and normocalcemic malignancy. In 37 hypercalcemic patients with various malignancies, we found detectable PTHRP1-86 concentrations in 35 (95%, mean 7.4 pmol/L, range 0.46-24.7). The data support the proposed humoral role of PTHRP in cancer-associated hypercalcemia and suggest that the assay has clinical utility in the differential diagnosis of hypercalcemia.

Antibodies, Monoclonal↗
PubMed1990

Production and characterisation of monoclonal antibodies to parathyroid hormone-related protein.

The production and characterisation of 17 monoclonal antibodies to human parathyroid hormone-related protein (PTH-rP) 1-34 is described. Five of the antibodies were shown to be of high avidity (Ka 4 X 10(10)-1.9 X 10(11) L/M) and able to detect 15-100 pg PTH-rP 1-34 per tube by RIA. None cross-reacted with PTH 1-34, and inhibition studies with peptide subfragments of PTH-rP 1-34 indicated that all recognise a central region extending from residues 9-18 to between residues 23 and 34. All antibodies tested cross-reacted with native PTH-rP in culture fluids from keratinocytes and squamous cancer cell lines and in human and bovine milk. The concentrations of PTH-rP 1-34 (ng/ml) in these fluids as determined by RIA were: keratinocytes 1-3, squamous cancer 0.2-2.5, human milk, up to 80. Selected antibodies coupled to Sepharose 4B were used to extract PTH-rP from biological fluids with high yields.

Animals↗
PubMed1990

Parathyroid-hormone-related protein in tumours associated with hypercalcaemia.

Parathyroid-hormone-related protein (PTHrP) messenger RNA was identified by in-situ hybridisation in seven tumours complicated by hypercalcaemia. In addition, among samples from normocalcaemic patients, it was commonly found in tumours of types frequently complicated by hypercalcaemia but was not found in tumours that are rarely complicated by hypercalcaemia. Positive results were obtained with both freshly frozen and archive paraffin-embedded material. These findings support the view that PTHrP is a common cause of hypercalcaemia in malignant disorders.

DNA Probes↗
PubMed1990

Treatment of hypercalcaemia of malignancy.

Hypercalcaemia is a common complication of malignancy. When severe, if treatment is thought to be justified, it should be treated with 2-3 litres of intravenous fluids per day combined with administration of an intravenous bisphosphonate drug. Mild to moderate hypercalcaemia is more difficult to manage satisfactorily. Oral steroids can be tried but are often ineffective, oral phosphate is effective but causes side-effects. It is likely that active oral bisphosphonate drugs will soon be available and these are likely to become the treatment of choice.

Calcitonin↗
PubMed1990

Effect of long-term hypophysectomy on ovarian follicle populations and gonadotrophin-induced adenosine cyclic 3',5'-monophosphate output by follicles from Booroola ewes with or without the F gene.

Long-term (i.e. approximately 70 days) hypophysectomy led to a significant (P less than 0.05) reduction in ovarian weight but no reduction in the total number of antral follicles (greater than 0.1 mm in diameter). In hypophysectomized ++ Booroola ewes (N = 8) follicles were always less than or equal to 3 mm and in hypophysectomized FF Booroola ewes (N = 6) follicles were always less than or equal to 2 mm in diameter; in ewes of both genotypes follicles reached diameters which were approximately 40% of their predicted final size at ovulation. Under in-vitro conditions, follicles from the FF and ++ hypophysectomized ewes produced significant increases in cAMP within 1 h of exposure to gonadotrophins (P less than 0.05) although no genotypic differences in cAMP production were noted. We conclude that ovarian follicles in FF and ++ ewes have absolute requirements for pituitary hormone on reaching diameters of 2 mm and 3 mm respectively and that appreciable numbers of antral follicles in ewes of both genotypes remain responsive to pituitary gonadotrophins despite prolonged deprivation of these hormones.

Animals↗
PubMed1990

Identification and partial characterization of parathyroid hormone-related protein in human and bovine milk.

Parathyroid hormone-related protein (PTHrP) was measured in human and bovine milk by radioimmunoassay (RIA) and bioassay, and the molecular forms characterized by gel chromatography and immunoblotting of affinity-purified PTHrP. Mean immunoreactive PTHrP(1-34) concentrations were 23 and 87 micrograms/l in human and bovine milk respectively. Bioactive (BIO) PTHrP concentrations determined by cyclic AMP production by ROS 17/2.8 cells correlated significantly (P less than 0.001) with those obtained by RIA (BIO = 1.04RIA--3.4, r = 0.939). Gel filtration of human and bovine milk identified several peaks with immunoactivity and bioactivity. Immunoblotting of affinity-purified PTHrP revealed multiple molecular species including components with mobilities similar to those of PTHrP and its subfragments. These studies confirm the presence of immuno- and bioactive PTHrP in milk and suggest that post-translational processing is complex and variable.

Animals↗
PubMed1990

Giant invasive prolactinoma: a case report and review of nine further cases.

Very large prolactinomas are rare and may be difficult to treat. We present the report of a patient with an exceptionally aggressive tumour which extended outside the skull and emerged within the internal jugular vein. Bromocriptine induced only transient suppression of serum prolactin. In vitro studies of tissue from this prolactinoma showed that although prolactin secretion was reduced by both bromocriptine and dopamine, neither agent affected cytoplasmic levels of prolactin mRNA, suggesting relative autonomy of prolactin synthesis. We reviewed the progress of nine other patients with very large prolactinomas and serum prolactin levels greater than 100,000 mU/l. In three cases, treatment with bromocriptine rapidly reduced tumour size and serum prolactin levels became normal, but in the other cases responses were slower and less marked. Substantial amounts of residual pituitary tumour were seen in all cases where serum prolactin remained above 1000 mU/l, but also in one case where serum prolactin returned to normal, showing that serum prolactin levels are not reliable indicators of tumour size. Two patients died: one developed a CSF leak, and one pneumococcal meningitis in the absence of recognized CSF leakage. This emphasizes the significant morbidity associated with very large prolactinomas. The ideal long-term treatment of these tumours remains uncertain, but bromocriptine therapy alone is often inadequate. Cases of apparent bromocriptine resistance may reflect abnormal regulation of prolactin gene expression.

Adult↗
PubMed1989

Comparison of different dose regimes of aminohydroxypropylidene-1,1-bisphosphonate (APD) in hypercalcaemia of malignancy.

1. The new intravenous bisphosphonate drug aminohydroxypropylidine bisphosphonate (APD) is effective in treating the hypercalcaemia of malignant disease, but the optimum dose regimen is not yet established. We have treated twenty-seven patients with malignant hypercalcaemia (corrected calcium greater than 3.00 mmol l-1) with intravenous APD, comparing three regimens of drug administration. 2. Patients were randomly allocated to receive a single dose of APD 30 mg on day 1 (group A, n = 9), two consecutive doses of 30 mg on days 1 and 2 (group B, n = 9) or a single 60 mg dose on day 1 (group C, n = 9). The patients were severely hypercalcaemic, and in nine (33%) the corrected serum calcium was higher than 4.00 mmol l-1 and all were severely ill: three patients died within 48 h of receiving the initial dose and seven died within the first week. 3. Serum calcium levels fell by day 7 in all patients: in group A, from 3.91 +/- 0.40 (s.d.) mmol l-1 to 2.91 +/- 0.49; in group B, from 3.59 +/- 0.33 to 2.63 +/- 0.23 mmol l-1; and in group C, from 3.71 +/- 0.43 to 2.66 +/- 0.39 mmol l-1. Complete response, defined by a nadir calcium (on days 5-12) below 2.60 mmol l-1 occurred in eleven of 24 surviving patients (4/9 in group A, 4/7 in group B, and 3/8 in group C). The remaining patients showed a partial response with serum calcium falling at least 0.25 mmol l-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Differences in the plasma concentrations of FSH and LH in ovariectomized Booroola FF and ++ ewes.

During 12 sampling days before ovariectomy the mean plasma FSH but not LH concentrations in FF ewes were higher (P less than 0.01) than those in ++ ewes (16 ewes/genotype). After ovariectomy increases in the concentrations of FSH and LH were noted for ewes of both genotypes within 3-4 h and the rates of increase of FSH and LH were 0.18 ng ml-1 h-1 and 0.09 ng ml-1 h-1 respectively for the first 15 h. From Days 1 to 12 after ovariectomy, the overall mean +/- s.e.m. concentrations for FSH in the FF and ++ ewes were 8.1 +/- 0.6 and 7.1 +/- 0.4 ng/ml respectively and for LH they were 2.7 +/- 0.3 and 2.1 +/- 0.2 ng/ml: these differences were not statistically significant (P = 0.09 for both FSH and LH; Student's t test). However, when the frequencies of high FSH or LH values after ovariectomy were compared with respect to genotype over time, significant F gene-specific differences were noted (P less than 0.01 for both FSH and LH; median test). In Exp. 2 another 21 ewes/genotype were blood sampled every 2nd day from Days 2 to 60 after ovariectomy and the plasma concentrations of FSH and LH were more frequently higher in FF than in ++ ewes (P less than 0.01 for FSH and LH). The F gene-specific differences in LH concentration, observed at 21-36 days after ovariectomy were due to higher mean LH amplitudes (P less than 0.025) but not LH peak frequency in FF than in ++ ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗