Unexplained bradycardia during craniotomy closure: the role of intracranial hypotension.
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Aged↗
Biomedical subjects
R A Fraser
Publications and source records attributed to R A Fraser.
Growth hormone: neurocrine and neuroendocrine perspectives.
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Animals↗
Efficient incorporation of transfected blastodermal cells into chimeric chicken embryos.
The formation of transgenic chimeric chickens for use in developmental studies and as intermediates in the production of transgenic chickens requires the incorporation of stably transfected blastodermal cells into a chimera. To obtain blastodermal cells, area pellucidae of stage X (Eyal-Giladi and Kochav, Dev. Biol. 49:321-337, 1976:E.-G.&K.) embryos were collected from unincubated, freshly oviposited Barred Plymouth Rock eggs and dissociated in 0.25% trypsin/0.04% EDTA (w/v) and 2% (v/v) chicken serum in phosphate-buffered saline (Ca2+ and Mg2+ free) at 4 degrees C for 10 min. The blastodermal cells were suspended in Dulbecco's Modified Eagle's Medium (DMEM) and transfected by lipofection with superhelical pmiwZ, a plasmid containing a hybrid lacZ gene encoding bacterial beta-galactosidase (beta-gal) under the control of a chicken beta-actin/Rous sarcoma virus promoter. A mixture of 2.5 micrograms Lipofectin and 1.56 micrograms pmiwZ in 250 microliters DMEM was incubated for 30 min at 37 degrees C and added to 500 microliters of 20-40,000 cells in suspension. Cells incubated with the transfection reagents in the presence or absence of pmiwZ were either plated and cultured for 48 h at 37 degrees C in 5% CO2/95% air, or injected through a shell window into the subgerminal cavity of White Leghorn stage X (E.-G.&K.) embryos previously exposed to 500-600 rads from a 60Co source, after which the window was sealed and the egg incubated at 38 +/- 1 degrees C for 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Ubiquitous distribution of growth hormone receptors and/or binding proteins in adenohypophyseal tissue.
Liver GH receptor (GHR)-like mRNA has been shown to be widely distributed throughout rat and rabbit pituitary glands. In the present study RNA extracted from rabbit anterior pituitary glands was reverse transcribed, and the cDNA amplified by the polymerase chain reaction (PCR) in the presence of 3'- and 5'-flanking oligonucleotide primers for the extracellular and transmembrane domains of the rabbit GHR. A 499-basepair (bp) fragment was generated, identical in size to that in rabbit liver, kidney, and adipose tissue. Digestion of this fragment with a restriction endonuclease (SalI) produced moieties of 280 and 219 bp, as observed for the amplified cDNA fragments from liver, kidney, and adipose tissue. In situ hybridization of a cRNA probe for the rabbit GHR with cryostat sections of the anterior pituitary gland was demonstrated. Specific hybridization occurred throughout the adenohypophysis and was present in somatotroph and nonsomatotroph cells, identified by hybridization of the same tissue sections with a complementary riboprobe for rat GH mRNA. Electron microscopy and immunogold staining, using monoclonal antibodies against the extracellular domain of the rat (MAb 263) or rabbit (MAb 7) GHR, demonstrated the presence of the receptor or binding protein throughout rat and rabbit anterior pituitary gland. Immunostaining occurred in somatotroph and nonsomatotroph cells and was widely distributed throughout the intracellular and nuclear compartments. In GH-secreting cells gold particles were specifically accumulated in the secretory granules and heterochromatin, but were also present in mitochondria, Golgi, endoplasmic reticulum, cytoplasm, nucleoplasm, and cellular and nuclear membranes. A similar distribution of GHR immunoreactivity was observed within rat and rabbit hepatocytes. Specific binding sites for radiolabeled ovine GH to cytosolic fractions and to crude solubilized preparations of plasma and nuclear membranes of the rat anterior pituitary gland were also demonstrated. The binding of the tracer to these sites was inhibited by prior exposure to MAb 263, which binds to epitopes in the ligand-binding domain of the rat GHR. These results provide evidence of 1) the expression and translation of the GHR gene in rat and rabbit adenohypophysis in 2) GH and non-GH-secreting cells, and 3) the presence of GH receptors/binding proteins throughout the intracellular and nuclear compartments of these cells.
Animals↗
Expression and translation of the growth hormone-receptor gene in the guinea-pig.
The refractoriness of guinea-pigs to the growth-promoting actions of exogenous GH has been suggested to be due to a deficiency or defect in tissue GH receptors or in GH-receptor gene expression. GH-receptor mRNA was, however, demonstrated by Northern blot analysis and by the polymerase chain reaction in extracts of guinea-pig liver, adipose tissue, brain, hypothalamus and pituitary gland. High-affinity, low-capacity binding sites for radio-labelled ovine GH were also demonstrated on the plasma membranes of guinea-pig liver and were similar to those in rat liver. These results demonstrate that the unresponsiveness of guinea-pigs to exogenous GH is not due to the absence of GH receptors.
Adipose Tissue↗
Expression of the growth hormone receptor gene in chicken pituitary glands.
Although GH has no direct effect on GH release from chicken pituitary glands, GH receptor mRNA similar to that in the rabbit liver was identified by Northern blot analysis in extracts of adult chicken pituitaries. Complementary (c) DNA, reverse transcribed from chicken pituitary RNA, was amplified by the polymerase chain reaction (PCR) in the presence of 3'- and 5'-oligonucleotide primers coding for the extracellular domain of the chicken liver GH receptor and was found to contain an electrophoretically separable fragment of 500 bp, identical in size to that in chicken liver. Digestion of this pituitary cDNA with NcoI produced expected moities of 350 and 150 bp. Amplification of chicken pituitary cDNA in the presence of oligonucleotide primers for the intracellular sequence of the chicken liver GH receptor produced an electrophoretically separable fragment of approximately 800 bp, similar to that in chicken liver. This fragment was cut into expected moieties of 530 and 275 bp after digestion with EcoRI. These PCR fragments were identified in extracts of the pituitary caudal lobe, in which somatotrophs are confined and account for the majority of endocrine cell types, and in the cephalic lobe, in which somatotrophs are lacking. Translation of the GH receptor mRNA in the pituitary gland was indicated by the qualitative demonstration of radiolabelled GH-binding sites in plasma membrane preparations, in pituitary cytosol and in nuclear membranes. These results provide evidence for the expression and translation of the GH receptor gene in pituitary tissue, in which GH receptors appear to be widely distributed within cells and in different cell types. GH may therefore have paracrine, autocrine or intracrine effects on pituitary function.
Animals↗
Hypo- and hypercalcemic peptides in fish pituitary glands.
Immunoreactive parathyroid hormone (irPTH), PTH-related peptide (PTHrp), and stanniocalcin-like peptides were detected in Coho salmon pituitary glands. The PTH, PTHrp, and stanniocalcin immunoreactivity of the salmon pituitary was separated by high-performance liquid chromatography purification into distinct peptide fractions that coeluted with pure preparations of these hormones. Stanniocalcin was localized by immunocytochemistry in the neurohypophysis and preoptic area of the platyfish brain, in areas in which irPTH has previously been detected in other teleosts. Although it is well established that the fish pituitary exerts hypercalcemic control over calcium metabolism, these results demonstrate the presence of hyper- and hypocalcemic peptides in teleost pituitary glands. The detection of PTHrp in the fish pituitary is the first report of its presence outside of mammalian species and suggests an early evolutionary divergence of PTH and PTHrp from an ancestral gene.
Animals↗
Growth hormone receptor gene: novel expression in pituitary tissue.
Specific hybridization of polyadenylated RNA, extracted from rat, rabbit and human pituitary glands with a 638 bp rabbit GH receptor (rGHR) cRNA was demonstrated by Northern analysis. In-situ hybridization of tissue sections with the probe demonstrated the localization of rGHR mRNA throughout the rat pituitary gland and its presence in the anterior lobe of the rabbit pituitary. Growth hormone binding sites on pituitary membranes were not, however, demonstrated by radioligand binding studies. Thus, although the GH receptor gene is expressed in pituitary tissue, functional GH receptors may not be inserted into pituitary plasma membranes.
Animals↗
Parathyroid hormone messenger ribonucleic acid in the rat hypothalamus.
Polyadenylated RNA, extracted from rat hypothalami, cross-hybridized with a RNA probe complementary in sequence to rat PTH (rPTH) messenger RNA (mRNA). Amplification of complementary DNA (cDNA) by the polymerase chain reaction also demonstrated the presence of rPTH mRNA in the rat hypothalamus and parathyroid gland. rPTH mRNA was localized by in situ hybridization in the paraventricular and supraoptic nuclei of the rat hypothalamus. These results demonstrate the expression of the PTH gene in the central nervous system of the rat in areas which suggest roles for PTH in neuroendocrine function.
Animals↗
Growth hormone receptors in hypothalamic and extra-hypothalamic tissues.
Central GH receptors (GHR) have been identified in hypothalamic and extra-hypothalamic tissues of rabbit and chicken brains. Plasma membranes of the rabbit brain demonstrated specific saturable high-affinity, low-capacity binding sites for 125I-labelled GH. RNA extracted from hypothalamic and extra-hypothalamic tissues of rabbit and chicken brains contained mRNA that hybridized with a cDNA probe for the rabbit liver GHR. This transcript was of a similar size to the major GHR mRNA moiety in rabbit liver. The expression of these moieties was age related, and higher in adult than in neonatal animals.
Age Factors↗
The prevalence and impact of pain after day-care tubal ligation surgery.
Empirical data from controlled studies using standardized, reliable measures on the amount and quality of pain after laparoscopic tubal ligation and the consequences of this pain on the activities of daily living are extremely scarce. In a study of 54 women admitted to a day-care unit for this procedure, validated measures were utilized to assess the incidence, intensity and duration of pain after tubal ligation (McGill Pain Questionnaire) and the impact of pain on the activities of daily living (Modified Functional Assessment Inventory). Psychological measures (Brief Symptom Inventory, Kranz Health Opinion Survey, and the State-Trait Anxiety Inventory) were employed to test their use as possible predictors for pain, analgesic usage and the time taken to resume a normal activity level after tubal ligation surgery. The results showed that pain is a significant problem after tubal ligation although pain rating scores over the 7-day study period were lower than those reported after major abdominal surgery. Eighty-five percent of our sample reported that pain and/or fatigue impacted on their recovery and contributed to an average delay of return to normal activity level of 4.4 days, not including the day of surgery. The psychological measures did not prove to be strong predictors of postoperative pain, time of return to normal activity level or analgesic usage. The most powerful predictor of return to normal activity was the total amount of pain experienced, as measured by the McGill Pain Questionnaire, during the 7 day post-operative period.
Activities of Daily Living↗
Naloxone infusion after prophylactic epidural morphine: effects on incidence of postoperative side-effects and quality of analgesia.
There have been conflicting reports of the value of naloxone infusions to prevent the side-effects associated with epidural morphine. In our study, 29 patients undergoing thoracotomies for pulmonary surgery received epidural morphine (0.1 mg.kg-1) shortly after induction of anaesthesia. One hour after arrival in the Recovery Room, one of four naloxone bolus and infusion sequences was administered: saline bolus followed by saline infusion; 0.4 microgram.kg-1 naloxone bolus followed by 0.4 microgram.kg-1.hr-1 naloxone infusion; 2.0 micrograms.kg-1 naloxone bolus followed by 2.0 micrograms.kg-1.hr-1 naloxone infusion; and 4.0 micrograms.kg-1 naloxone bolus followed by 4.0 micrograms.kg-1.hr-1 naloxone infusion. Although with the number of patients studied, there were no statistically significant differences among groups, clinically, there was a trend toward decreased analgesia with all three naloxone infusion doses as determined by analgesic requirements, longest analgesic-free period and visual analogue pain scores. In addition, side-effects occurred in all groups. We conclude that prophylactic naloxone, used in this manner, is not an appropriate technique for the prevention of side-effects associated with epidural morphine used for the prevention of pain after thoracotomy.
Aged↗
Characterization of antisera raised against hypocalcin (teleocalcin) purified from corpuscles of Stannius of rainbow trout, Salmo gairdneri.
Highly specific antisera were raised against hypocalcin, a 54-kDa glycoprotein purified from the corpuscles of Stannius (CS) of rainbow trout, Salmo gairdneri. The specificity of the antisera was determined by using Ouchterlony's double immunodiffusion test, radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), and immunocytochemistry. In the double immunodiffusion test, a single precipitin line was formed between the antisera and hypocalcin. Both RIA and ELISA studies showed that serial dilutions of hypocalcin, teleocalcin, and CS extracts produced dose-response curves, whereas rat FSH, chicken LH, bovine TSH, salmon calcitonin, bovine parathyroid hormone, and human angiotensins I and II failed to cross-react with the antiserum. Immunoreactive hypocalcin was demonstrated in the plasma of a teleost (flounder), but not of an elasmobranch (dogfish). In the immunocytochemistry, most of the gland cells showed strong immunoreaction with the antisera, whereas some cells displayed no immunoreactivity.
Animals↗
Usefulness of preoperative inferior petrosal vein sampling in Cushing's disease.
Adrenocorticotropic hormone (ACTH) levels from the inferior petrosal sinuses and peripheral veins were measured in 10 patients with Cushing's disease. All patients had normal or indeterminate computed tomography scans. In 9 of the 10 patients the petrosal vein sampling showed a gradient between pituitary ACTH and peripheral ACTH verifying the supposition of pituitary dependent hypercortisolism. In seven cases preoperative ACTH levels lateralized tumor to one side of the gland. In six of these cases tumor was found at that location at surgery. In the seventh case, no tumor was identified at surgery and that half of the gland was resected. Nine patients were cured following transsphenoidal excision of tumor.
Adenoma↗
Tumours acquire their vasculature by vessel incorporation, not vessel ingrowth.
This study was designed to investigate the early development of tumour circulation using a transplantable mouse mammary adenocarcinoma. Tumour cells (10(6] were injected subcutaneously into the flank and groups of treated mice were killed at 24 h intervals up to 12 days; the tumours and surrounding tissues being processed by standard histological methods. Sections of tumour were sub-divided into neoplastic tissue, vessels and connective tissue using computer-assisted morphometric techniques: the host tissue around the tumour was similarly quantified for vessels and connective tissue. With increasing tumour size, the proportion of vessels within tumours rapidly increased to reach a plateau of approximately 1.5 per cent of tumour volume, a 400 per cent increase on the vascular density of normal subcutaneous tissue. Within tumours, vascular density was always higher at the periphery than the centre. The most pronounced increase in vascular density affected the host tissue around the tumour. It is not clear why vascular development is most prominent outwith the tumour when postulated angiogenic factors, such as tumour angiogenesis factor, are presumably released within. Our results imply, however, that tumours acquire their vasculature by infiltration into, and expansion between, a network of newly formed vessels in the surrounding connective tissue.
Adenocarcinoma↗
One-stage meningomyelocele closure and ventriculoperitoneal shunt placement.
Thirteen myelodysplastic neonates were observed to have birth head circumferences below the 90th percentile but ventriculomegaly on preoperative computed tomograms. These infants all required later shunting for hydrocephalus. We then began performing a one-stage procedure of meningomyelocele closure and shunt insertion in all neonates with ventriculomegaly on preoperative computed tomograms without regard to head circumference. Seventeen of 24 additional patients have had the one-stage procedure; 4 have required later shunting; 1 shunt infection (6%) was encountered. We conclude that neonatal head circumference does not predict hydrocephalus, and that ventriculomegaly on preoperative computed tomograms identifies neonates who will require shunting.
Cerebrospinal Fluid Shunts↗
The influence of mammalian and teleost somatostatins on the secretion of growth hormone from goldfish (Carassius auratus L.) pituitary fragments in vitro.
The effect of various vertebrate somatostatins (SRIF) on basal growth hormone (GH) secretion from goldfish pituitary fragments was studied using an in vitro perifusion system. SRIF-14 caused a rapid and dose-dependent decrease in the rate of GH release from goldfish pituitary fragments. The half-maximal effective dose (ED50) of SRIF-14 was calculated as 1.3 nM following exposure to two minute pulses of increasing concentrations of SRIF-14, whereas the ED50 of SRIF-14 calculated after continuous exposure to sequentially increasing doses of SRIF-14 was 65 nM. This difference suggests that the pituitary fragments were less responsive to SRIF-14 in the latter experiment, possibly as a result of previous exposure to SRIF-14. SRIF-28 was found to be equipotent with SRIF-14 in decreasing basal GH secretion from the goldfish pituitary. In contrast, catfish SRIF-22, a uniquely teleost SRIF isolated from catfish pancreatic islets, did not alter GH secretion. These results provide further support for the hypothesis that SRIF-14 or a very similar molecule functions as a GH release-inhibiting factor in teleosts, indicating that this action of SRIF-14 has been fully conserved throughout vertebrate evolution.
Animals↗
Assessment by ELISA of passively acquired protection against infectious bursal disease virus in chickens.
The level of maternal antibody to infectious bursal disease (IBD) virus in the circulation of one-day-old layer strain chickens was found to be on average, 45% of the antibody titre in their respective dam, while the minimum ELISA titre which protected against a challenge of 1000 CID50 of virus was 400. Maternal antibody was found to disappear from the circulation of these crossbred chickens with a half-life of 6.7 days. From these data it is possible to estimate the ELISA titre necessary in vaccinated hens to provide the desired duration of passive protection; protection being assessed by an ELISA which measures IBD viral antigen in the bursa of Fabricius following challenge.
Animals↗