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Biomedical subjects

C Sterling

Publications and source records attributed to C Sterling.

16 recordsLinked to original sources
PubMed1992

Phosphorylation and activation of tyrosine hydroxylase in PC18 cells: a cell line derived from rat pheochromocytoma PC12 cells.

Treatment of rat pheochromocytoma PC18 cells (a variant subclone of PC12 cells) with forskolin produced increased activity and phosphorylation of tyrosine hydroxylase. In contrast, treatment of the PC18 cells with 56 mM K+, A23187, phorbol-12-myristate-13-acetate (PMA) or phorbol-12,13-dibutyrate (PDB) did not affect the activity and only slightly increased the phosphorylation of tyrosine hydroxylase. None of the treatments except forskolin increased cyclic AMP levels in PC18 cells. Furthermore, 45Ca2+ uptake into PC18 cells was not affected by 56 mM K+, PDB or forskolin; however, A23187 increased 45Ca2+ uptake 4-fold over basal uptake. Nevertheless, no activation and little increase in phosphorylation of tyrosine hydroxylase was observed in PC18 cells treated with A23187. When tyrosine hydroxylase levels in PC18 cells were elevated by treatment with dexamethasone, activation of tyrosine hydroxylase by 56 mM K+, PDB or A23187 was still not observed. Both purified Ca2+/calmodulin-dependent protein kinase and cyclic AMP-dependent protein kinase catalyzed the phosphorylation of tyrosine hydroxylase purified from PC18 cells in vitro. Furthermore, crude cell extracts from PC12 cells and PC18 cells possessed Ca2+/calmodulin-dependent protein kinase activity that catalyzed the phosphorylation of purified tyrosine hydroxylase. These results suggest that tyrosine hydroxylase activity in PC18 cells is regulated by a cyclic AMP-dependent mechanism. However, due to a number of abnormalities the Ca(2+)-dependent mechanisms do not result in the activation of tyrosine hydroxylase and only slightly increase the phosphorylation of the enzyme in PC18 cells.

Animals↗
PubMed1991

Activation of tyrosine hydroxylase by nicotine in rat adrenal gland.

The administration of nicotine activates tyrosine hydroxylase in the rat adrenal gland. This activation is apparently maximal 25 min after a single subcutaneous injection of nicotine at 2.3 mg/kg. Repeated injections of nicotine (seven injections once every 30 min) are associated with a persistent activation of adrenal tyrosine hydroxylase for at least 3 h. The nicotinic receptor antagonist hexamethonium does not significantly inhibit the nicotine-mediated activation of tyrosine hydroxylase in innervated adrenal glands. However, hexamethonium completely blocks the activation of adrenal tyrosine hydroxylase by nicotine in denervated adrenal glands. Furthermore, even though a single injection of nicotine activates tyrosine hydroxylase in both innervated and denervated adrenal glands, repeated injections of nicotine do not activate tyrosine hydroxylase in denervated adrenal glands. Our results suggest that the systemic administration of nicotine activates adrenal tyrosine hydroxylase by two mechanisms: (1) via direct interaction with adrenal chromaffin cell nicotinic receptors; and (2) via stimulation of the CNS leading to the release from the splanchnic nerve of substances that interact with adrenal chromaffin cell receptors other than the nicotinic receptor.

Adrenal Glands↗
PubMed1988

Attenuation of spontaneous hypertension in rats by a vasopressin antagonist.

Although abnormalities in the vasopressin system have been reported in spontaneously hypertensive rats (SHR), neither short-term nor long-term administration of the vasopressin antagonist d(CH2)5-Tyr(Me)arginine vasopressin (AVP), which selectively blocks the action of vasopressin on vascular (V1) receptors, altered the course of hypertension in SHR. In the current study, long-term administration of a different vasopressin antagonist, d(CH2)5-D-Tyr(Me)VAVP, to SHR and Wistar-Kyoto rats (WKY) from 4 to 12 weeks of age significantly attenuated the development of systolic hypertension in SHR (p less than 0.05) without altering blood pressure in normotensive WKY. The antagonist was delivered subcutaneously by osmopump at 0.1 microgram/hr. Systolic blood pressure was monitored twice weekly by tail plethysmography beginning at 5 weeks of age. In a second group of SHR, the drug infusion was continued until 18 weeks of age. In this group, the attenuation of systolic hypertension by the drug was extended and became more prominent (p less than 0.007). Resting mean arterial pressure measured by indwelling catheters in the conscious state at 18 weeks of age was significantly reduced in the antagonist-treated SHR (144 +/- 4 vs 157 +/- 4 mm Hg; p less than 0.05). Heart rate also was significantly reduced by the drug (351 +/- 6 vs 392 +/- 7 beats/min; p less than 0.001). Following measurement of mean arterial pressure in the rats at 18 weeks of age, the osmopumps were removed and systolic blood pressure, mean arterial pressure, and heart rate were observed until 22 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The evaluation of a hostel ward. A controlled study using modified cost-benefit analysis.

A controlled modified cost-benefit evaluation of a hostel ward caring for new long-stay patients is described and results are presented for the first two years. In some respects the residents of the hostel ward had fewer psychotic impairments than those remaining on the wards of the district general hospital, mainly because the latter seem to continue to acquire such defects, while the former have remained relatively unchanged. The hostel ward residents also develop superior domestic skills, use more facilities in the community, and are more likely to be engaged in constructive activities than controls. These advantages were not purchased at a price, since the cost of providing this form of care for these patients has cost less than care provided by the district general hospital.

Adolescent↗
PubMed1985

Douglas House: a new type of hostel ward for chronic psychotic patients.

A new type of hostel ward is described in which domestic activities take the place of attendance at a day centre or industrial workshop. Residents no longer depend on the institution for meals, cleaning, or social activities. The programme is resident-orientated, and individual treatment plans are designed and effected using a points system. The emphasis of group activities is on communication and living skills. The hostel ward is able to care for our most disabled patients who are thought to need 24-hour nursing care.

Activities of Daily Living↗
PubMed1979

Lymphocytosis in rats treated with polyacids.

Inoculation of rats i.v. with dextran sulfate or polymethacrylic acid causes lymphocytosis. Electron microscopy of sections of cervical lymph nodes in control rats showed active passage of small lymphocytes through the high endothelial cells (HEC) of the post-capillary venules. In treated rats there was no indication of such passage: the HEC were free of small lymphocytes; and in about 25% of the venules apparently stationary lymphocytes, lacking microvilli, were found appressed to the luminal walls of the HEC.

Acrylic Resins↗
PubMed1974

Surface properties of extracellular malaria parasites: morphological and cytochemical study.

Morphological and cytochemical surface characteristics of isolated malaria parasites (Plasmodium berghei) and host erythrocytes were compared by electron microscopy by using thin section and carbon replica techniques. Erythrocytes were uniform in shape and had fine, granular surfaces. In contrast, free parasites exhibited a variety of sizes, shapes, and surface textures. Fine surface stippling was a common topographical feature of isolated parasites. Small, infective forms often had patterned surfaces resulting from the protuberance of an underlying thick intermediate layer. Results of cytochemical analysis using a sialophilic colloidal iron stain indicated that the malaria parasite's surface lacked exposed sialic acid groups which would normally give rise to a net negative surface charge common to erythrocytes. Biochemical assay demonstrated that malaria parasites contained about one-half the amount of sialic acid per unit weight as did control red cell extracts. Similarly, external acidic mucopolysaccharide coats of free parasites, as revealed by ruthenium red staining were extremely thin as compared with the thick glycocalyx layer of red cells. Lipid plaques at the surface of parasites and red cells were localized by lipophilic iron colloid staining. Although the gross patchwork distribution of plaques was somewhat similar for the two cell types, the parasites were stained more intensely and had a closer-knit patchwork pattern than those exhibited by the erythrocytes. Such findings indicate that there are slight differences in the arrangement of phospholipids at the surfaces of limiting membranes of host cells and parasites. The significance of the above cytochemical surface properties of the malaria parasite (which are seemingly akin to those of intracellular organelles is discussed in relation to certain host-parasite interactions, such as parasite adhesion to target cells and enhanced clearance of extracellular parasites.

Cell Membrane↗