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J A Pitcock

Publications and source records attributed to J A Pitcock.

At least 19 recordsLinked to original sources
PubMed1991

Secretion of medullipin I by isolated kidneys perfused under elevated pressure.

1. Medullipin I (Med I) is a hormone extracted from renal papillae and its renomedullary interstitial cells (RIC). Med I is stimulated by elevation of the renal artery perfusion pressure. 2. When isolated normal rat kidneys were perfused either with oxygenated blood or with 5% albumin bubbled with O2 at elevated perfusion pressures, Med I appeared to be secreted into the renal venous effluent (RVE). Addition of Tween 20, treatment of the assay rat with SKF 525A, inhibitor of cytochrome P-450 and removal of the liver from the systemic circulation prevented vasodepression of both the RVE and extracted Med I. The lipid in the RVE gave the same dose-response as extracted Med I. 3. Lowering the renal artery perfusion pressure below normal inhibited the secretion of Med I. As the perfusion pressure was elevated Med I secretion appeared to increase. 4. Previous observations and the present study support the view that the renin-angiotensin system and the Medullipin system are double feedback systems involved in blood pressure control.

Angiotensin II↗
PubMed1991

Medullipin system. Generation of medullipin II by isolated kidney-liver perfusion.

Perfusion of isolated normal rat kidneys with blood at elevated blood pressure (180-200 mm Hg) followed by perfusion of the renal perfusate through an isolated normal rat liver under venous pressure yielded in the plasma of the hepatic effluent a vasodepressor lipid having the chromatographic and biological characteristics of medullipin II. These findings support the view that medullipin II is the final product of the renohepatic axis of blood pressure control.

Animals↗
PubMed1991

Black bones following long-term minocycline treatment.

During a surgical procedure, black vertebrae were observed in a 42-year-old white woman. An undecalcified iliac crest bone biopsy specimen revealed intense fluorescence compatible with tetracycline labeling and osteoporosis. A urinary screening test was negative for amino acids. The patient had been treated with minocycline hydrochloride (100 to 300 mg/d) for at least 6 years. Since minocycline is known to discolor many body tissues, it is likely that the black discoloration of bone in our patient was caused by the long-term intake of the antibiotic.

Acne Vulgaris↗
PubMed1989

Histopathology of severe renal vascular damage in blacks.

During the 1970s renal biopsies were obtained after blood pressure had been controlled in 41 black patients in Memphis who had severe hypertension plus excretory renal failure. An additional 13 binephrectomy specimens were also studied. This material yielded significant information on the state of the renal arteries--arterioles under these circumstances. Fibrinoid necrosis of the afferent glomerular arteriole and proliferative glomerulitis were not noted. Rather, the vascular lesion characterized by the accumulation of smooth muscle cells and mucopolysaccharide in the intima attended by a marked narrowing of the lumen was dominant. This lesion caused pronounced ischemia associated with obsolescence of glomeruli, atrophy, and fibrosis (end-stage kidney). This lesion has been renamed musculomucoid intimal hyperplasia as a result of changes revealed by electron microscopic and histochemical studies. Since this study the incidence of this severe vascular disease of the kidney in the same geographic area has been markedly reduced. There are a number of possible reasons for this change in incidence, but a major one appears to be improved treatment of hypertension and better compliance with antihypertensive therapy. Why such extreme changes occur in a subset of hypertensive blacks is not known. It is apparent that without improved antihypertensive treatment, this type of end-stage renal disease due to severe vascular damage will continue to be encountered.

Adult↗
PubMed1989

Effect of calcitonin and vitamin D in osteoporosis.

Vitamin D has complex effects in bone: it stimulates matrix formation and bone maturation but also enhances osteoclastic activity and may influence differentiation of bone cell precursors. Calcitonin inhibits the function of osteoclasts, reducing bone resorption, thus, the combination of vitamin D and calcitonin could result in a positive bone balance. We tested the hypothesis that chronic treatment with high doses of vitamin D (150,000 U/week), moderate doses of salmon calcitonin (120 MRC U/week), and adequate Ca supplementation (1 g/day) could be beneficial in osteoporosis. Thirteen women with postmenopausal osteoporosis received this treatment for 2-6 years (mean 3.5 years). No side effects, hypercalcemia, or hypercalciuria occurred. There was marked reduction in bone pain. The fracture rate in 11 patients with vertebral compression fracture was 240/1,000 patient years, threefold lower than the reported 834 fractures for untreated patients of similar age. Single photon bone densitometry of the radius did not change. Iliac crest bone biopsies obtained at the initiation and conclusion of the study showed a 43% increment in trabecular bone volume (P = 0.0003), without changes of the normal osteoid thickness, surface, and volume. Because single photon densitometry reflects mostly cortical bone, the data suggest that the combination of vitamin D and calcitonin increases trabecular bone mass and prevents the fall of cortical bone mass in osteoporosis. Previous reports suggest that calcitonin alone or with small doses of vitamin D increased bone mass for about 2 years. The present study suggests a prolonged beneficial effect of the combination of high doses of vitamin D with rather moderate (less than 150 MRC U/week) doses of calcitonin in postmenopausal osteoporosis.

Aged↗
PubMed1989

Biologic contrasts between medullipin I and vasoactive glyceryl compounds.

Medullipin I causes a delayed onset depressor response when injected intravenously into rats. The glyceryl compounds selachyl alcohol (SA) and monoolein (MO) cause similar vasodepression. The neutral lipid 1-O-hexadecyl-2-acetyl-sn-glycerol (HAG) was suggested by Blank et al to be medullipin I (Med I, formerly ANRL). Biologic comparisons were made between Med I and various glyceryl compounds, including SA, MO, HAG, alkyl glyceryl ethers of phosphatidyl choline (termed APRL by us), diacylated SA, and the n-butyl boronic acid derivative of SA and MO. The n-butyl boronic acid derivative of Med I also was evaluated. The delay in onset of the depressor response to Med I was reduced by the injection of Med I into the portal vein; that of SA and MO was not. Med I, SA, and MO were activated by the liver, while APRL and HAG were not. Tween 20 inhibited Med I, SA, and MO, but not APRL and HAG. Proadifen (SKF 525A) inhibited Med I, but not SA and MO. The n-butyl boronic acid derivatives of SA, MO, and Med I were inactive. Med I, like SA and MO, appeared to have two hydroxyl groups in close proximity. It was concluded that Med I is neither HAG, APRL, SA, nor MO.

Animals↗
PubMed1989

The renal antihypertensive endocrine function: its relation to cytochrome P-450.

Unclipping the Goldblatt hypertensive rat lowers the blood pressure by cells in the renal papilla, the renomedullary interstitial cells (RIC), secreting a hormone that is part of a vasodilator system. A vasodilator, termed medullipin I, can be extracted from the renal papilla. Medullipin I and the renal venous effluent following unclipping have identical biologic properties. Medullipin I appears to be the agent secreted by the kidney following unclipping. Both medullipin I and the renal venous effluent must traverse the liver to be active. Medullipin I is converted in the liver to its active form, medullipin II. The blood pressure-lowering effect of both medullipin I and the renal venous effluent after unclipping are blocked by SKF 525A, the inhibitor of cytochrome P-450. The relation of the kidney to the liver was tested using the rate of decline of the blood pressure after unclipping as an index of the endocrine antihypertensive function of the kidney--acceleration of the decline being considered as increased function, decrease of the decline as decreased function. Five compounds: BW755C, phenobarbital, ketoconazole, eicosatetraynoic acid (ETYA) and butylated hydroxytoluene (BHT), and two manipulations: uretero-caval anastomosis (UCA) and removal of the liver from the circulation were used followed by unclipping. BW755C, inhibitor of both cyclo-oxygenase and lipoxygenase, potentiated the antihypertensive function to a maximum. It is reasoned that inhibition of the first two pathways of arachidonic acid metabolism potentiates the third pathway, the cytochrome P-450 pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1988

Glycosaminoglycans of the rat renomedullary interstitium: ultrastructural and biochemical observations.

The rat renal papillary interstitum which contains abundant proteoglycans is a unique area important in renal function. These proteoglycans were studied ultrastructurally by ruthenium red fixation and staining and phosphate-buffered fixation before and after enzyme digestion. A tissue culture of rat renomedullary interstitial cells, the predominant cell of the renal papillary interstitum, was studied for its ability to synthesize proteoglycans and the proteoglycans were then analyzed. Tissue slices of whole rat renal inner medulla were also evaluated for their synthetic ability. In combination, these studies indicate that the dominant glycosaminoglycan is hyaluronic acid. The tissue culture of rat renal medullary interstitial cells synthesized glycosaminoglycans and on analysis, hyaluronic acid was found to be the chief glycosaminoglycan secreted by the renomedullary interstitial cells. Combined with the removal of the proteoglycans from tissue by leech hyaluronidase and testicular hyaluronidase, this suggests that the dominant glycosaminoglycan is hyaluronic acid. Hyaluronic acid is also synthesized by the intact papilla confirming the findings with the tissue culture. However, in addition, sulfated glycosaminoglycans were also synthesized by the intact papilla, presumably the product of the noninterstitial components of the papilla.

Animals↗
PubMed1988

Focal myositis in the hand.

Focal myositis is a rare, benign, pseudotumor of skeletal muscle that is usually seen as a steadily enlarging soft tissue tumor in an otherwise healthy patient. Focal involvement of muscle with severe myopathic and inflammatory changes characterize the histology. The natural course of this disorder is spontaneous regression. We report the case of a 7-year-old girl with focal myositis of the index lumbrical muscle. This is the first reported incidence of focal myositis that involves muscle of the hand.

Child↗
PubMed1988

Morphometric studies of the renomedullary interstitial cells.

The renomedullary interstitial cell (RIC) is a unique cell found in the renal medullary interstitium among the collecting ducts, Henle's loop, and the vasa recta. A combination of morphologic and physiologic studies has defined some of the properties of this cell, which is the apparent source of the mediators of the antihypertensive function of the kidney. These may include prostaglandins (PGE2), APRL or platelet activating factor, and the incompletely defined neutral lipid, ANRL (or medullipin), the most likely candidate for this function. The lipid droplets in the RIC apparently are the precursors of the mediator(s). Degranulation of the RIC by an experimental maneuver usually indicates increased activity of these cells. The presence of abundant well-granulated RIC in a kidney indicates a resistance of that animal to the induction of salt-sensitive forms of experimental hypertension. There is definite evidence for an extrarenal antihypertensive function of the RIC mediators, but an intrarenal effect also is considered.

Animals↗
PubMed1988

Hypercalcemia.

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Aluminum↗
PubMed1987

Passive transfer studies with type II collagen antibody in B10.D2/old and new line and C57Bl/6 normal and beige (Chediak-Higashi) strains: evidence of important roles for C5 and multiple inflammatory cell types in the development of erosive arthritis.

C5-normal B10.D2/new line mice were susceptible to passively transferred arthritis from purified type II collagen antibody, and in vitro studies demonstrated that, when bound to cartilage, this antibody readily activated complement C5 to C5a. C5-deficient B10.D2/old line mice failed to develop passively transferred arthritis, despite the deposition of antibody and C3 along the cartilage surface. C57Bl/6 mice were susceptible to passively transferred arthritis, which was characterized in histopathologic studies as an erosive synovitis involving multiple inflammatory cell types. In contrast, neither clinical nor histologic evidence of arthritis was observed in C57Bl/6 mice with the beige mutation (Chediak-Higashi syndrome).

Animals↗
PubMed1987

Selachyl alcohol as an oral antihypertensive agent: a preliminary note.

Selachyl alcohol (SA) is a mono-oleyl glyceryl ether. It has certain biologic activities similar to those of the antihypertensive neutral renomedullary lipid (ANRL) derived from the renal papilla and its renomedullary interstitial cells (RIC). These include a vaso-depressor effect following bolus injection and a requirement for hepatic activation for the development of biological activity. In view of this similarity to ANRL, it appeared worthwhile to test the antihypertensive action of SA when given via the GI tract. Accordingly, pure SA was given either by gavage or by tube into the stomach or duodenum of one-kidney, one-clip hypertensive rats (5-10 mg per dose). The role of hepatic activation was demonstrated by comparing the BP response to bolus injection of SA and ANRL with and without the presence of an intact circulation to the liver. Administration of SA via the GI tract resulted in a significant decline in BP without tachycardia or weight loss. In the absence of a circulation to the liver, neither SA nor ANRL was active. SA appears to be an effective antihypertensive agent when given via the GI tract.

Animals↗
PubMed1987

Biphasic effect of dexamethasone on urinary prostaglandins in rats: relation to alterations in renal medulla triglycerides and prostaglandin metabolism.

This study was designed to characterize the time course of the effects of dexamethasone (2.5 mg kg-1 week-1, sc) on the renal arachidonate-prostaglandin (PG) system and to define the effect of the steroid on the interstitial cells of the renal inner medulla (RIC). The RIC are rich in triglycerides, which, due to their high content of arachidonic acid, may be a source of arachidonate for PG synthesis during conditions of phospholipase inhibition. After 1 day of dexamethasone treatment, the urinary excretion of PGE2 and PGF2 alpha was reduced to about 50% of the control value (P less than 0.05), and angiotensin II-induced release of arachidonic acid and PGs from renal medulla slices was blunted (P less than 0.05). In contrast, dexamethasone treatment did not affect ionophore A23187-induced release of PGs and arachidonic acid from renal medulla slices. By day 3 of dexamethasone treatment, urinary excretion of PGE2 and PGF2 alpha had returned to control levels, and by days 5 and 14 the excretion rates of both were clearly increased (P less than 0.05). The rise in urinary PG excretion was accompanied by a reduction of renal 15-hydroxyprostaglandin dehydrogenase activity, augmentation of renal medulla microsomal PG synthetase activity, and diminution of renal medulla triglycerides, the latter associated with a reduction in the number of RIC and of RIC osmiophilic granules. This study demonstrates that the effects of dexamethasone on urinary PG are biphasic; this may reflect the changing balance between the opposing actions of the steroid on renal PG-synthesizing and catabolizing enzymes and the inhibitory effect on the synthesis of renal PG that is linked to activation of specific renal lipases by endogenous factors such as angiotensin II.

Angiotensin II↗
PubMed1986

Electron microscopic detection of virus particles in the rhino mouse.

The rhino mouse, an experimental model for systemic lupus erythematosus, was found to have murine leukemia virus particles present in the skin. Immunoperoxidase studies with anti-type C virus antibody indicated viral antigen presence in the sebaceous cells and surrounding follicular cysts of the dermis. Electron microscope studies show virus particles, both type C extracellularly and type A intracellularly, around follicular cysts. Virus particle was labeled with specific ferritin-conjugated antitype C virus antibody.

Animals↗