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Biomedical subjects

C Oliver

Publications and source records attributed to C Oliver.

At least 361 records · Page 20Linked to original sources
PubMed1977

Inorganic trimetaphosphatase as a histochemical marker for lysosomes in light and electron microscopy.

A new cytochemical method is presented for the light and electron microscopic localization of lysosomes in mineralized and soft tissues. Inorganic trimetaphosphate is used as substrate in a lead chelate incubation medium at pH 3.9. Lysosomes in several tissues are strongly reactive, and reaction product is frequently present in Golgi saccules and GERL. The reaction can be differentiated from acid glycerophosphatase activity, is relatively insensitive to fixation and demineralization procedures, and the reaction is often complete after short incubation times.

Animals↗
PubMed1977

Dopamine in hypophysial portal plasma of the rat during the estrous cycle and throughout pregnancy.

Catecholamine levels in hypophysial portal plasma were determined in pregnant and non-pregnant female rats as well as in intact and castrated male rats, using a radioenzymatic assay for the simultaneous determination of dopamine, norepinephrine, and epinephrine in 50 mul of plasma. Portal and arterial blood were collected from anesthetized rats at 7 mul/min for 60 min. During the collection, blood was kept at 0 C, a temperature at which endogenous catecholamines were relatively stable. Dopamine was present in high concentrations in hypophysial portal plasma thorughout pregnancy, attaining a level near 20 ng/ml on the 20th day of gestation. Dopamine levels in arterial plasma from the same rats were low or undetectable (0.4--0.8 ng/ml1. Norepinephrine and epinephrine was undetectable (less than 0.6 ng/ml) in portal as well as arterial plasma from these rats. The major catecholamine in extracts of the hypothalamus from pregnant rats was norepinephrine, whereas that in the posterior pituitary was dopamine. Dopamine levels in portal plasma collected during proestrus, estrus, diestrus 1, and diestrus 2, were 1.32 +/- 0.21 (mean +/- SE), 3.87 +/- 0.96, 3.11 +/- 0.73, and 2.3 +/- 0.45, respectively. Dopamine in portal plasma from intact and from castrated male rats was approximately 0.6 ng/ml. Norepinephrine and epinephrine were not detectable in either portal or arterial plasma from these animals. It is concluded 1) that dopamine is secreted into hypophysial portal blood in significant quantities during pregnancy, 2) that hypothalamic secretion of dopamine in cyclic rats is greatest during the day of estrus and early diestrus and at least on the day of proestrus, and 3) that these findings support the view that dopamine of hypothalamic origin may have an important role in the regulation of anterior pituitary function.

Animals↗
PubMed1976

[Melanotropic hormone in the green frog (Rana esculenta): biochemical and radioimmunological study].

The alpha-MSH levels in the frog hypophysis were measured by use of a sensitive ans specific radioimmunoassay. Sephadex G-50 gel chromatography of frog pars distalis and pars intermedia extracts showed that frog hypophyseal MSH was chemically related to synthetic alpha-MSH. Rat tissue homogenates were capable of degrading frog pars intermedia MSH as well as synthetic alpha-MSH. These results provide evidence that the frog hypophysis--pars intermedia and pars distalis--contains an alpha-MSH-like peptide.

Animals↗
PubMed1976

Fatal complications of tracheotomy.

Thirty-six of 403 deaths after tracheotomy were direct complications of that procedure. Arterial hemorrhage caused three deaths, venous bleeding, seven. Airway obstruction resulted in six fatalities. Tracheoesophageal fistula caused five deaths. Eight deaths were due to infection and sepsis. Tension pneumothorax developed in one patient and the remaining six deaths were due to cardiopulmonary collapse. Many of the complications of tracheotomy can be avoided with accurate knowledge of anatomic variations, ideal operating conditions, proper technic, careful arterial and venous hemostasis, routine postoperative chest x-ray films, sterile suction technic, proper use of soft cuffed tracheotomy tubes, adequate humidification, and careful postoperative blood gas monitoring.

Airway Obstruction↗
PubMed1976

Immunoreactive alpha-MSH and ACTH levels in rat plasma and pituitary.

A radioimmunoassay is described for the measurement of alpha-melanocyte-stimulating hormone (alpha-MSH). The antibody was produced in rabbits by immunization with alpha-MSH coupled to bovine serum albumin with carbodiimide. The antibody did not react significantly with ACTH, beta-MSH, or 6 fragments of ACTH. The sensitivity and reliability of the assay were improved by employing a simple plasma extraction procedure. When applied to a 2 ml plasma sample, the detection limit of the radioimmunoassay was 6 pg/ml. ACTH was measured with a sensitive and specific radioimmunoassay previously described for humans and adapted for the rat. The anti-ACTH serum cross-reacted with the biologically active portion of alpha-p ACTH and not with alpha-MSH, beta-MSH or the alpha-p 17-39 and alpha-p 25-39 fragments of ACTH. The detection limit was 20 pg/ml. Plasma and pituitary alpha-MSH and ACTH had the same immunoreactivity as synthetic alpha-MSH and ACTH. alpha-MSH and ACTH contents of the rat neurointermediate lobe were 1398 +/- 360 (SE) ng and 28.2 +/- 2.9 ng, respectively, while in the anterior lobe they were 102 +/- 31 ng and 551 +/- 36 ng, respectively. The plasma alpha-MSH concentration at 8 AM in male rats was 64 +/- 8 pg/ml when the plasma ACTH concentration was 92 +/- 15 pg/ml. Over a 24-hour period two peaks of plasma alpha-MSH were observed, one at 4 AM (142 +/- 35 pg/ml) and the other at 4 PM (139 +/- 26 pg/ml). Plasma ACTH was higher at noon (151 +/- 43 pg/ml) and 4 PM (130 +/- 48 pg/ml). Short-term exposure to ether induced a transient increase in alpha-MSH level 5 min later and a rapid return to normal levels. Plasma ACTH increased significantly 2.5 min after the onset of ether stress and remained high for 30 min. Two hours' exposure to ether did not change plasma alpha-MSH, although a 3-fold increase in plasma ACTH was observed. Haloperidol injection was followed by a large increase in plasma alpha-MSH, whereas ACTH levels increased similarly after saline and Haloperidol injection. Corticoid administration reduced ACTH, but not alpha-MSH. Three weeks after adrenalectomy, alpha-MSH levels had not changed but ACTH levels had increased ten-fold. These data indicate that alpha-MSH is secreted in the rat, and that the regulation of its secretion is different from that of ACTH.

Adrenocorticotropic Hormone↗
PubMed1976

Inhibition of degradation and measurement of immunoreactive thyrotropin-releasing hormone in rat blood and plasma.

A radioimmunoassay (RIA) for thyrotropin-releasing hormone (TRH) is described. The cross-reactivity of the antiserum was tested with 26 analogs of TRH, 5 amino acids, and LH-releasing hormone. Use of this RIA revealed that inactivation of TRH by rat blood was prevented if the blood was frozen and thawed prior to its incubation with TRH. This procedure did not interfere with the binding of TRH to its antibody. The degradation of TRH by blood or plasma was inhibited by 2,3-dimercaptopropanol (BAL) or benzamidine, but these compounds nonspecifically inhibited the binding of [125I]TRH to anti-TRH. At 37 C, 50% of the synthetic TRH added to rat blood was degraded within seconds, whereas at 1C, 60-65% was recovered after 90 min. When blood was frozen and thawed prior to its incubation with TRH at 1C, essentially all of the hormone was recovered after a 90-min incubation period. In contrast, incubation of TRH with frozen and thawed blood at 37 C resulted in a rapid loss of TRH. BAL (10 mM) or bensamidine (100 mM) afforded complete protection for TRH for at least 30 min at 1 C. At 37 C, protection was incomplete. Exposure of rats to cold (2C) resulted in a significant increase in serum TSH levels, but TRH was undetectable (less than3 pg) in 100 mul of blood regardless of whether the blood contained BAL (10 mM) or benzamidine (100 mM), or was frozen quickly and thawed before RIA. However, when 5-8 ml of trunk blood was extracted with methanol, 8-11 pg/ml of TRH was found, and the TRH levels were slightly but significantly elevated after cold exposure.

Amidines↗
PubMed1976

Influence of L-prolyl-L-leucyl-glycine amide on growth hormone secretion in normal and acromegalic subjects.

Melanocyte Release-Inhibiting Peptide (MRIP-I) did not affect circulating levels of ACTH, LH, FSH, TSH,ORL, betaMSH and insulin when iv infused (5.0 mg in 5 min plus 0.4 mg/min for 70-115 min), while it significantly reduced serum GH response to hypoglycemia in normal subjects and lowered serum GH levels in acromegalics. There was no correlation between the fall in serum GH after MRIP and after dopaminergic drugs in acromegaly. These data are compatible with either a direct suppressive action exerted by MRIP-I at pituitary level or an extra-pituitary effect not involving dopaminergic pathways. It can be spec-lated that since labelled MRIP-I accumualtes in the pineal and melatonin blunts GH response to hypoglycemia, the pineal gland might be involved in the MRIP-I-induced suppression of GH secretion.

Acromegaly↗
PubMed1976

Age-related accumulation of ceroid-like pigment in mice with Chediak-Higashi syndrome.

The Chediak-Higashi Syndrome (CHS) is a rare inherited disorder occurring in man and several animal homologs including the beige mouse; it is characterized by pigmentary dilution, susceptibility to pyogenic infections, and the presence of enlarged lysosomes in many cell types. Beige mice 6 months of age and older were found to have darkened livers, kidneys, and spleens, accompanied by splenomegaly. A fluorescence microscopic survey of tissues from beige mice revealed marked accumulations of a microscopic survey of tissues from beige mice revealed marked accumulations of a yellow autofluorescent pigment inhepatocytes, renal proximal tubule cells, and splenic macrophages. Additionally, large amounts of hemosiderin were present in the spleen. In beige mice, the pigment was noted in animals as young as 1 to 2 weeks of age and gradually increased in amount as the animals aged. A histochemical investigation of the pigment showed that it was ceroid-like in nature and contained in lysosomes. Ultrastructurally, the pigment was composed of lipid-like droplets embedded in a dense matrix and surrounded by a limiting membrane. The accumulation of ceroid-like material in beige mice may be a reflection of the metabolic disturbance which underlies CHS.

Aging↗
PubMed1975

A morphological and quantitative study of tumor blood flow. I. During growth and immune rejection.

We have used serial microangiography and radioactive 133 Xe to study microvascular morphology and quantify blood flow in Walker 256 carcinomas implanted in rat tails during growth and immune rejection. No previous angiographic/quantitative studies during immune rejection are reported. Two tumor groups were identified. Group A grew rapidly, with a two- to six-fold increase in blood flow, and caused death in 10 days. Group B grew more slowly, and increased blood flow two to four times. At 6 to 8 days postimplant the B tumors diminished in size; blood flow decreased and extensive lymphocytic infiltration developed. By 21 days all evidence of the tumor had disappeared. The rejection appears to be cell-mediated, and the high incidence (65-70%) to be related to the number of tumor cells and/or presence of accumulated antigen in the innoculum. Microangiographic changes during immune rejection were specific, and included marked tortuosity of feeding vessels and a "ghostlike" fading out of tumor vessels, quite unlike the appearance of necrosis.

Angiography↗
PubMed1975

Transport of thyrotropin-releasing hormone from cerebrospinal fluid to hypophysial portal blood and the release of thyrotropin.

The capacity of the medium eminence to transport thyrotropin-releasing hormone (TRH) from cerebrospinal fluid (CSF) to hypophysial portal blood, and the ability of TRH when introduced into a lateral ventricle to stimulate TSH release from the pituitary gland were investigated. Male rats were injected either intraventricularly or intravenously with 0, 1, 10, or 100 ng of TRH, and plasma TSH concentrations were determined at various times thereafter. TRH administration via both routes resulted in substantial release of TSH. Following intraventricular injection of TRH, there was a delay in reached maximal TSH concentration when compared with the faster elevation and faster decline in TSH concentrations which followed intravenous injection of the same dose of TRH. In a second experiment, 7 muCi of [3H]TRH were introduced intraventricularly or intravenously, and hypophysial portal and arterial blood were simultaneously collected and examined for the presence of radioactivity. The intraventricular injection of [3H]TRH resulted in a peak of radioactivity in portal blood within minutes, which was maintained for 20--30 min and then declined. The concentration of radioactivity in arterial blood from the same animals was considerably lower than that in portal blood. The intravenous administration of [3H]TRH resulted in radioactive peaks in both portal and arterial blood with a higher concentration of radioactive substances in arterial blood. However, the level of radioactivity in portal blood following intravenous injection of [3H]TRH comprised no more than 5--10% of that found following intraventricular administration of the saem dose. The data support the view that TRH is able to cross the medium eminence from CSF into hypophysial portal blood and that it is capable of stimulating the pituitary gland to release TSH.

Animals↗