Studies on the role of prostaglandins in ovulation using the isolated perfused ovary as a model.
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Animals↗
Biomedical subjects
M R Clark
Publications and source records attributed to M R Clark.
Excessive binding of the natural anti-alpha-galactosyl IgG to sickle red cells: enhancement of red cell destruction by a physiological process.
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Anemia, Sickle Cell↗
A luteinizing hormone-releasing hormone agonist for the prevention of chemotherapy-induced ovarian follicular loss in rats.
In an attempt to prevent chemotherapy-induced ovarian follicular loss, [D-Leu6, des-Gly10-NH2]-luteinizing hormone-releasing hormone ethylamide (LHRHa) was given subcutaneously to Sprague-Dawley cycling female rats in two daily doses of 2.5 micrograms starting 2 days prior to and concomitant with cyclophosphamide (CTX) (5 mg/kg/day for 21 days). Four groups of female cycling rats (10 in each) received either no treatment, CTX alone, CTX + LHRHa, or LHRHa alone. One ovary from each animal was serially sectioned, stained, and examined for the number and size of follicles. CTX produced a significant reduction in the total number of follicles. The pool of growing follicles (medium to large, greater than 30 microns in diameter) appeared to be vulnerable to the cytotoxic effect of CTX. LHRHa resulted in a significant reduction in the number of medium-to-large follicles and an increase in the number of small follicles. When given in combination with CTX, LHRHa significantly further reduced the number of medium-to-large follicles, significantly increased the number of small follicles, and resulted in an increase in the total number of follicles. Chronic LHRHa treatment resulted in functional deprivation of follicles from gonadotropins, thus halting the process of recruitment from the quiescent pool of primordial follicles into the CTX sensitive pool and thereby preserving the functional potential of the ovary.
Animals↗
Erythrocyte deformability changes in autoimmune hemolytic anemia during development of NZB mice and their (NZB/NZW)F1 hybrid.
NZB and B/W hybrid mice develop compensated hemolytic anemia during the first year of their life. By the age of 3-5 months, their erythrocytes show evidence of spherocytosis, increased osmotic fragility and decreased whole cell deformability, as measured by ektacytometry, a laser diffraction technique. The presence of spherocytes with decreased surface area/volume ratio was confirmed by scanning electron microscopy and osmotic gradient ektacytometry. Whereas these abnormalities persisted and worsened in the NZB mice with further growth, they gradually improved and reverted to normal by the age of 12 months in B/W mice. This spontaneous improvement seems to be due to the accumulation of red cell membrane lipids reflecting the lipemia of immune complex nephritis in B/W mice. The implications of these findings in the modulation of autoimmune hemolytic anemia are discussed.
Age Factors↗
Selected ionic and metabolic characteristics of human red cell populations separated on stractan density gradients.
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Adenosine Triphosphate↗
Effects of oxygen inhalation on endogenous erythropoietin kinetics, erythropoiesis, and properties of blood cells in sickle-cell anemia.
The role of oxygen therapy in sickle-cell anemia is not established, and its effects on erythropoiesis and on the rheologic properties of sickled erythrocytes are controversial. When three patients with sickle-cell anemia who were not in crisis or infected breathed oxygen at a rate of 5 liters per minute continuously through nasal prongs for five days, there was a rapid decline in erythropoietin levels that had initially been elevated, a delayed fall in the number of reticulocytes, and a fall in the number of irreversibly sickled cells, which, in two of the subjects, preceded the suppression of reticulocytosis. After cessation of oxygen therapy, erythropoietin levels and the number of irreversibly sickled cells increased promptly, followed by an increase in the number of reticulocytes. Calculated erythropoietin half-lives were 1.51 to 2.92 hours, and clearances were 43 to 84 ml per minute during oxygen administration. These are normal values. In two subjects, the number of irreversibly sickled cells rose to exceed base-line values after oxygen therapy was discontinued, and both subjects had acute painful episodes at this time. We conclude that in patients with sickle-cell anemia, substantial changes in erythropoiesis and in the rheologic properties of blood occur in association with oxygen inhalation and that when oxygen therapy is administered to such patients, it should be given intermittently rather than continuously.
Anemia, Sickle Cell↗
Detection of monoclonal antibodies against cell surface antigens: the use of antiglobulins coupled to red blood cells.
An antiglobulin-coupled red cell assay is described for screening monoclonal antibodies against cell surface antigens. A monoclonal antibody specific for rat immunoglobulin kappa chains was coupled to red blood cells and used to detect binding of rat monoclonal antibodies to cells attached to the wells of microtitre plates. The method was found to be simpler and more rapid than the alternative enzyme-linked binding assay and useful for rapid screening and selection of antibodies for use as differentiation markers of human and mouse haemopoietic cells.
Animals↗
Concurrent Cushing's and Zollinger-Ellison syndromes in a patient with islet cell carcinoma. Case report and review of the literature.
This report documents the simultaneous occurrence of Cushing's and Zollinger-Ellison syndromes in a patient with islet cell carcinoma. The clinical concurrence of these two syndromes has been recorded in only three previous case studies, while three other case reports record evidence suggesting the presence of both gastrin and ACTH within the tumor but without clinical sequelae. In the present report, evidence based on multiple clinical and biochemical data supports the concept that both syndromes are a result of "ectopic" hormone production by the tumor.
ACTH Syndrome, Ectopic↗
Intralingual naloxone reversal of morphine-induced respiratory depression in dogs.
A descriptive study was done to determine whether naloxone is efficacious in reversing morphine-induced respiratory depression in dogs when administered intralingually into the ventral lateral surface of the tongue. Mean minute ventilation was depressed to half of resting baseline levels using fixed intravenous doses of morphine sulfate. Intralingually administered naloxone reversed this respiratory depression rapidly within one minute, and resulted in a greater than fourfold increase in mean minute ventilation above established baseline levels.
Animals↗
Concurrent sickle cell anemia and alpha-thalassemia. Effect on pathological properties of sickle erythrocytes.
The concurrence of sickle cell anemia and alpha-thalassemia results in less severe hemolytic anemia apparently as a result of reduced intraerythrocytic concentration of hemoglobin S and its retarded polymerization. We have evaluated the effect of alpha-globin gene number on several interrelated properties of sickle erythrocytes (RBC) that are expected to correlate with the hemolytic and rheologic consequences of sickle cell disease. The irreversibly sickled cell number, proportion of very dense sickle RBC, and diminished deformability of sickle RBC each varied directly with alpha-globin gene number. Sickle RBC density was a direct function of the mean corpuscular hemoglobin concentration (MCHC). Even in nonsickle RBC, alpha-globin gene number varied directly with RBC density. Despite differences in alpha-globin gene number, sickle RBC of the same density had the same degree of deformability and dehydration. These data indicate that the fundamental effect of alpha-thalassemia is to inhibit the generation of sickle RBC having high density and MCHC, and that the other beneficial effects of sickle RBC are secondary to this process. The less consistent effect on overall clinical severity reported for subjects with this concurrence may reflect an undefined detrimental effect of alpha-thalassemia, possibly on the whole blood viscosity or on sickle RBC membrane-mediated adherence phenomena.
Anemia, Sickle Cell↗
Cardiovascular changes in group B streptococcal sepsis in the piglet: response to indomethacin and relationship to prostacyclin and thromboxane A2.
Seventeen piglets were infected with a continuous intravenous infusion of live group B beta-hemolytic streptococci (GBS). Hemodynamic changes were recorded, and blood samples were drawn for measurement of thromboxane B2 (TxB2) (stable metabolite of thromboxane A2) and 6-keto-PGF1 alpha (stable metabolite of prostacyclin). Control animals (n = 9) received only bacteria, while treatment animals (n = 8) received indomethacin, 3 mg/kg IV, 15 min after the start of the bacterial infusion. Control animals responded to the bacteria within 15 min with marked elevation in mean pulmonary artery pressure (Ppa) from 15 +/- 8 to 39 +/- 6 mm Hg and decline in PaO2 from 80 +/- 11 to 51 +/- 6 mm Hg and cardiac output (CO) from 0.24 +/- 0.07 to 0.13 +/- 0.07 liters/min/kg. Mean arterial blood pressure (AoP) significantly decreased from baseline value of 95 +/- 13 to 51 +/- 32 mm Hg by 180 min. In animals treated with indomethacin, these changes were reversed or significantly attenuated. The hemodynamic changes were associated temporally with elevations in plasma concentrations of TxB2 or 6-keto-PGF1 alpha. In the first 60 min, TxB2 levels in both groups correlated with Ppa (r = 0.72, p less than 0.001) and PaO2 (r = -0.60, p less than 0.001). A strong negative correlation between TxB2 and CO was observed over the first 180 min (r = -0.73, p less than 0.001). There was a statistically significant correlation between AoP and 6-keto-PGF1 alpha concentration between 60 and 180 min (r = -0.54, p less than 0.002). Indomethacin improved the hemodynamic function in this model of GBS sepsis.(ABSTRACT TRUNCATED AT 250 WORDS)
6-Ketoprostaglandin F1 alpha↗
Red cell membrane and cation deficiency in Rh null syndrome.
A 52-yr-old multiparous white female was found to have Rh null blood type. She had macrocytic anemia, with reticulocytosis (15%-20%), of long duration. Although stomatocytes in peripheral blood were numerous and osmotic fragility was increased, suggesting increased cell water, the RBC cation content, and thus cell water, was decreased. Cell dehydration was confirmed by an increased proportion of high density RBC on Stractan density gradients. The deformability of RBC from four gradient subpopulations was measured in the ektacytometer as a function of suspending medium osmolality. Analysis of these measurements showed an abnormal reduction in cell surface area with increasing cell density, thus explaining the increased osmotic fragility of whole blood. This was confirmed by a density-dependent reduction in cell cholesterol content, suggesting membrane instability in vivo. Rh null subpopulations showed a twofold increase in both ouabain-sensitive and -insensitive Na-K ATPase activity and 86Rb transport, even in the dense fraction with the fewest reticulocytes. No membrane protein or glycoprotein abnormality was detected by SDS-PAGE. The associated deficiencies of both membrane surface area and cation content in Rh null cells, as well as increased Na-K pump activity, suggest a pleiotropic functional interrelationship among Rh antigen, membrane stability, and cation regulation.
Anemia, Macrocytic↗
Haemopoietic progenitor cell heterogeneity revealed by a single monoclonal antibody, YW 13.1.1.
Rapid segregation and purification of haemopoietic progenitor cells by simple methods is necessary for a proper analysis of the control of early haemopoiesis. In this paper we describe the use of a rat monoclonal antibody, YW 13.1.1, for that purpose. This reagent reacts with more than 90% of foetal liver cells but spares stem cells. A single-step lysis with antibody and complement achieves a tenfold enrichment for early progenitor cells. The marker also shows an increasing level of expression on the three defined subsets of erythroid progenitor cells. This parallels their developmental pathway and erythropoietin responsiveness. Simple quantitative considerations therefore permit separation of cells at different stages of erythropoiesis.
Animals↗
Activation of protein kinase in the bovine corpus luteum by phospholipid and Ca2+.
A new species of protein kinase has been identified in cytosol preparations from bovine corpora lutea. Enzyme activity required the simultaneous presence of Ca2+ and phospholipid, and was also enhanced by glyceryl dioleate. Phosphatidylserine was the most effective phospholipid for stimulating histone phosphorylation. Other phospholipids capable of supporting enzymic activity were, in order of decreasing activity, phosphatidylinositol, phosphatidic acid, cardiolipin and phosphatidylglycerol. Several other phospholipids tested were ineffective. A cyclic AMP-dependent protein kinase was also present in the luteal cytosol. This enzyme activity was eliminated by protein kinase inhibitor without affecting the Ca2+- and phospholipid-stimulated activity. Lysine-rich histone (IIIS) was a much better substrate than type-IIA histone for Ca2+- and phospholipid-dependent phosphorylation. Ca2+ and phospholipid also enhanced phosphorylation of endogenous luteal cytosol protein. Calmodulin, alone or in the presence of Ca2+, was unable to increase phosphorylation. Trifluoperazine inhibited protein kinase activity stimulated by Ca2+ and phospholipid. These data suggest that a phospholipid-sensitive, Ca2+-dependent protein kinase may provide an important link between hormonally-induced changes in phospholipid metabolism and corpus-luteum function.
Animals↗
Polyamines do not inhibit erythrocyte ATPase activities.
To test whether physiologic elevation of red cell polyamine levels might explain Na pump inhibition in sickle cells or uremic red cells, we have studied the effect of putrescine, spermidine and spermine on red cell membrane ATPase and Na-K active transport. Measurement of the ouabain-sensitive influx of 86Rb into intact cells showed no effect of spermine. However, cells became depleted of ATP during incubation with spermine. By 48 h, the cells showed substantial potassium loss and moderate sodium gain. Because the low permeability of red cell membranes for polyamines might have obscured some direct effects on intracellular processes, we measured active transport of 22Na out of red cell ghosts that had been resealed in the presence of 5 mmol/l spermine. In addition, we measured the Na-K, Mg, and Ca ATPase activities of broken membrane preparations in the presence of spermine, spermidine and putrescine. Polyamines had no direct effect on cation transport in red cells, although possible adverse effects on red cell metabolism could have a secondary effect on cation regulation.
Adenosine Triphosphatases↗
Prostaglandin levels in preovulatory follicles from rabbit ovaries perfused in vitro.
Prostaglandin (PG) levels in follicular fluid from preovulatory follicles of rabbit ovaries perfused in vitro were measured in order to compare PG changes in this model system with those that occur in vivo and in isolated, LH-treated follicles in vitro. One ovary from each rabbit was perfused without further treatment (control). The other ovary was exposed to LH (0.1 or 1 microgram/ml) beginning 1 hour (h) after initiation of perfusion. Samples of perfusion medium were taken at frequent intervals for measurement of PGE, PGF, progesterone and estradiol 17 beta. The perfusions were terminated when the first ovulation occurred or appeared imminent as judged by changes in the size and shape of the follicles. Follicular fluid was then rapidly aspirated from all large follicles on both ovaries for PGE and PGF measurement. Ovulations occurred only in the LH-treated ovaries. Progesterone and estradiol levels were significantly elevated in the perfusion medium within 1 h of LH treatment in comparison to controls. PG levels in perfusion medium from the control and LH-treated ovaries were not different throughout perfusion and increased in both groups. In contrast, PG levels measured in follicular fluid from LH-treated ovaries were 4- to 5-fold greater than in fluid from control ovaries. It is concluded that ovulation induced by LH in this experimental model is accompanied by an increase in follicular PG levels similar to that seen in other in vivo and in vitro models. This difference in follicular PG levels between the LH-treated and control ovaries is, however, not reflected in the perfusion medium.
Animals↗
Gonadotropin-releasing hormone (GnRH) stimulates phosphatidylinositol metabolism in rat granulosa cells: mechanism of action of GnRH.
This report describes the effects of gonadotropin-releasing hormone (GnRH; gonadoliberin) and an agonist, [D-Ala6, des-Gly10]GnRH ethyl amide (GnRHa), on phospholipid metabolism in rat granulosa cells isolated from mature Graafian follicles. As indicated by the incorporation of 32PO4, GnRHa rapidly (less than 2 min) stimulated the labeling of phosphatidic acid and phosphatidylinositol but had no effect on the labeling of other phospholipids. Increased phosphatidylinositol labeling was also observed when myo-[2-3H]inositol was incubated with granulosa cells in the presence of GnRHa. Increases in labeling were dependent on the dose of GnRH and time of incubation. Thyrotropin-releasing hormone and a specific GnRH antagonist had no effect on labeling, but a GnRH antagonist prevented the stimulatory action of GnRH. In addition, treatment with GnRHa slightly increased the levels of phosphatidylinositol (15%) in 60-min incubations but had no effect on the levels of other phospholipids. Significant increases in progesterone accumulation were observed after 30 min of incubation with GnRHa, and further increases were correlated with the time of incubation. The stimulatory action of GnRH on phospholipid metabolism and progesterone accumulation was not related to increases in cyclic nucleotide accumulation. In incubations lasting up to 30 min, GnRHa had no effect on cAMP accumulation. However, a transient decrease in cGMP levels was observed in response to GnRHa. These studies suggest that the rapid and specific effects of GnRH on phospholipid metabolism in rat granulosa cells represent early events in the action of GnRH.
Animals↗