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M Kashgarian

Publications and source records attributed to M Kashgarian.

At least 19 recordsLinked to original sources
PubMed1992

The cardiac conduction system in the rat expresses the alpha 2 and alpha 3 isoforms of the Na+,K(+)-ATPase.

The sodium pump is crucial for the function of the heart and of the cardiac conduction system, which initiates the heartbeat. The alpha (catalytic) subunit of this pump has three isoforms; the alpha 1 isoform is ubiquitous, but the alpha 2 and alpha 3 isoforms are localized to excitable tissue. Because rodent alpha 2 and alpha 3 isoforms are relatively sensitive to ouabain, which also slows cardiac conduction, we studied heart-cell-specific expression of pump isoform genes. Multiple conduction-system structures, including sinoatrial node, bundle branches, and Purkinje strands, had prominent, specific hybridization signal for alpha 2 and alpha 3 isoforms compared with adjacent working myocytes. This gene-expression approach may be useful for labeling conduction tissue and also for localizing specific membrane channels and receptors in this system.

Animals↗
PubMed1992

The effect of cyclosporine administration on the cellular distribution and content of cyclophilin.

Cyclophilin (CYP), an intracellular protein sharing amino acid sequence identity with the enzyme peptidyl-prolyl cis-trans isomerase has become the leading candidate for the receptor responsible for cyclosporine biological effects. Avid binding of CYP to cyclosporine and immunosuppressive cyclosporine metabolites has been demonstrated, while nonimmunosuppressive cyclosporine metabolites have tended not to bind to cyclophilin. A previous immunohistochemical analysis documented that CYP localized principally to the cytoplasmic cellular compartment, but nuclear staining was observed among some cells. This study was undertaken to more precisely define the ultrastructural distribution of CYP, and to determine whether CYP cellular content was affected by CsA therapy. Untreated Wistar rats or those receiving 7 days of CsA (15 mg/kg/day, i.p.) were anesthetized, perfusion-fixed in situ, and sacrificed. Analyses of lymph node, spleen, thymus, kidney, liver, heart, brain, and ileum used an affinity purified, rabbit anticyclophilin IgG. Transmission electron microscopy was performed after staining with anti-CYP using a horseradish peroxidase/biotin/avidin technique. Quantitative immunofluorescence was measured by confocal microscopy using anti-CYP, with a biotin/avidin/phycoerythrin technique. Cyclophilin localized to the cytoplasmic compartment--however, association with mitochondria endoplasmic reticulum, Golgi, and with the nuclear membrane among lymphocytes, as well as cells from kidney, liver and ileum--was documented. Cyclophilin was not identified within the nucleus proper. Tissues obtained from animals receiving CsA exhibited a generalized increase in CYP content compared with tissues from untreated controls, suggesting the possibility that CsA may exert a regulatory influence upon CYP gene activation. Collectively, the data were consistent with the hypothesis that CYP exerts a central role in cellular metabolism, and that CsA-mediated biologic effects result from the CsA/CYP interaction.

Amino Acid Isomerases↗
PubMed1992

Induction and intracellular localization of HSP-72 after renal ischemia.

To determine whether heat shock proteins (HSPs) might be active in cellular recovery following transient ischemia, we examined rat kidneys for 70-kDa HSP (HSP-70) mRNA expression, protein elaboration, and intracellular localization after 45 min of renal ischemia and reflow of 15 min, 2, 6, and 24 h. Inducible HSP-70 mRNA is present at 15 min of reperfusion, peaks between 2 and 6 h, and falls by 24 h. Inducible 72-kDa HSP (HSP-72) protein accumulates progressively through 24 h and is found in both soluble and microsomal fractions following ischemia. Within proximal tubules, immunofluorescent localization of HSP-72 is restricted to the apical domain at 15 min, is dispersed through the cytoplasm in a vesicular pattern at 2 and 6 h, and has migrated away from the apical domain at 24 h. A portion of the vesicular HSP-72 is associated with lysosomes; no intranuclear HSP-72 is detected. The course of mRNA induction, protein elaboration, and HSP-72 localization coincides with previously described changes in proximal tubule morphology and polarity following sublethal ischemic injury. HSP-72 may be instrumental in cellular remodeling and restitution of epithelial polarity during recovery from ischemic renal injury.

Animals↗
PubMed1992

Can experienced clinicians predict the outcome of lupus nephritis?

The ability of four experienced clinicians to predict short-term outcome (serum creatinine level at 1 year) and long-term outcome (renal insufficiency) was evaluated in 87 patients with lupus nephritis. The correlational agreement and the accuracy of their predictions were contrasted with the actual outcomes observed and with statistically generated prognostic regression models. In contrast to previously published data, all four clinicians predicted both short-term outcomes (P < 0.001) and long-term outcomes (P < 0.02) well. The clinicians' predictions approximated that of a statistically generated computer model for both agreement and accuracy for renal function at 1 year. The four clinicians identified nearly identical clinical variables as important in determining prognosis. Provision of biopsy data to the clinicians improved short-term and long-term prediction slightly. The value of the statistical models was 'validated' by demonstrating that three of the four clinical variables identified by the models, but not by the clinicians, could enhance clinical prediction (P < 0.05). In addition, the extent of tubulo-interstitial involvement on biopsy, a predictor that has recently received increased attention, could improve the long-term clinical predictions of all four clinicians (P < 0.05).

Adolescent↗
PubMed1992

Mesangial cell-matrix interactions. Effects on mesangial cell growth and cytokine secretion.

Glomerulonephritis (GN) results in proliferation of mesangial cells (MC), infiltration of inflammatory cells, and accumulation of extracellular matrix (ECM) proteins in the mesangium. Locally secreted cytokines may stimulate MC growth or the secretion of inflammatory mediators by MC. Interleukin-6 (IL-6) may be an autocrine cofactor in the pathogenesis of mesangioproliferative GN. We studied the regulation of IL-6 secretion by MC in response to MC-derived cytokines and ECM proteins. IL-6 secretion is stimulated in a dose-dependent manner by IL-1 alpha, TNF-alpha, and PDGF. Constitutive and LPS-induced release of IL-6 by MCs is reduced on collagen type I (coll I) compared-with uncoated surfaces. IL-6 release on collagen type IV (coll IV), however, is enhanced. In addition, MC on coll I exhibit a sixfold higher growth rate than cells on uncoated surfaces. The reduction of cytokine secretion in parallel with the stimulation of MC growth by coll I suggests that exposure to coll I may result in a change from secretory to proliferative phenotype in vitro.

Animals↗
PubMed1992

Extracellular matrix protein: gene expression and synthesis in cultured rat mesangial cells.

Production of extracellular matrix (ECM) by mesangial cells (MCs) contributes to progressive glomerulosclerosis. Our previous immunocytochemical studies on ECM production by MCs [1] were extended by examining the gene expression and protein synthesis using Northern blotting and ELISA. ELISA demonstrated that fetal calf serum (FCS) stimulated the synthesis of collagen I (CI), III (CIII) and IV (CIV), and laminin (LM). At and after confluence, the amounts of CIII, CIV and LM per DNA amount began to decrease, whereas that of CI did not. Northern blotting indicated that the mRNA expressions for CIV and LM were transiently increased by FCS. The mRNA expressions for CI and CIII decreased until confluence and then returned to the initial levels. These results suggest that FCS and cellular confluence affected the synthesis of ECM at both the level of gene expression and protein synthesis. The mRNA expressions for CIV and LM paralleled the protein synthesis and appeared tightly regulated. CI and CIII synthesis and mRNA expression were not coordinate and were not regulated in the same manner as the basement membrane matrix components.

Animals↗
PubMed1991

Plasmapheresis and subsequent pulse cyclophosphamide versus pulse cyclophosphamide alone in severe lupus: design of the LPSG trial. Lupus Plasmapheresis Study Group (LPSG).

A group of clinics are collaborating in the Lupus Plasmapheresis Study Group (LPSG) to investigate whether repeated plasmapheresis prior to pulse cyclophosphamide improves the therapeutical results in severe systemic lupus erythematosus (SLE). The underlying rationale is the hypothesis that plasmapheresis 1) eliminates pathogenic autoantibodies and immune complexes and 2) induces compensatory lymphocyte activation via feedback mechanisms between circulating antibodies and their respective clones ("antibody rebound"). It should be possible to utilize this enhanced activity for increased clonal deletion if pulse cyclophosphamide is applied shortly after plasmapheresis. Accordingly, in a randomized study, the LPSG will be comparing the repeated application of pulse cyclophosphamide alone with a treatment involving repeated plasmapheresis prior to the cyclophosphamide pulses in severe SLE. A third arm of the study will be gathering experience with a more intensified procedure. This overview summarizes the most important details of the planned study.

Combined Modality Therapy↗
PubMed1991

Redistribution of cellular energy following renal ischemia.

In order to elucidate the pattern of redistribution of cellular energy and the restoration of basic cellular metabolism following an ischemic renal insult, suspensions enriched in proximal tubule segments were studied after 45 min of bilateral artery occlusion and 15 min and 2 h of reflow from rats given either normal saline (control), ATP-MgCl2 (which enhances postischemic recovery of ATP), or alpha, beta-methyl adenosine diphosphate (AMPCP), which inhibits nucleotide degradation during ischemia. In non-ischemic control animals, approximately half of the energy is distributed to functional pump activity and half directed for non-transport purposes. When cellular ATP is reduced to 56% of control values, functional pump activity is significantly reduced to 61% of control, while energy delegated for non-transport purposes is decreased by a significantly smaller increment to only 78% of control at 15 min of reflow. In animals given ATP-MgCl2, the cellular and metabolic profile at 15 min of reflow was no different from ischemic control animals with cellular ATP levels similar at 58%. However, by 2 h, cellular ATP levels had increased significantly to 74%, and this was associated with a redistribution of cellular energy to functional pump activity (119% of control) with little change in non-transport function (76%). In animals treated with AMPCP, the cellular ATP levels were 74% of controls, similar to ATP-MgCl2-treated rats after 2 h of reflow. Despite the differences in reflow interval, the distribution of cellular energy was similar (functional pump activity 120% and non-transport activity 79%). By 2 h, cellular ATP was at 95% and both functional pump activity and non-transport activity were 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1991

Multinuclear spermatozoa associated with polyploidy.

We are reporting on a possible association between multinucleated spermatozoa and polyploidy after in vitro fertilization. The semen from the male partner of a couple with 40% polyploidy on three in vitro fertilization attempts was examined by light and transmission electron microscopy. In that sample 10% to 12% of spermatozoa demonstrated conjoined or double heads. The significance of these findings is discussed.

Adult↗
PubMed1991

Predictors of one year outcome in lupus nephritis: the importance of renal biopsy.

The short-term prognosis of lupus nephritis was evaluated by assessing serum creatinine 12 months after renal biopsy in 87 patients with lupus nephritis. On univariate analysis, significant clinical and laboratory predictors of this outcome included clinical signs of renal injury (serum creatinine, 24-hour urinary protein, prolonged renal disease, nephrotic syndrome, serum albumin), as well as thrombocytopenia, older age, and coexisting illness or hypertension at the time of biopsy. On renal biopsy, diffuse proliferative nephritis, higher activity, chronicity, or tubulointerstitial scores, or subendothelial or subepithelial electron dense deposits predicted a higher serum creatinine 12 months after biopsy. A clinical predictive model was developed which included as independent predictors serum creatinine, age, platelet count and 24-hour urinary protein. Any one of three biopsy variables added information to the clinical prediction model: a marked quantity of subendothelial deposits (p = 0.02), a higher activity index score (p = 0.02), or the presence of diffuse proliferative lupus nephritis (p = 0.05). However, the relative predictive accuracy of the clinical model did not improve with the addition of any of the biopsy variables. The value of renal biopsy in lupus nephritis is discussed based on the ability of biopsy information to confirm the prognosis, to add new predictive information for a group of subjects, and to improve predictive accuracy for individual patients.

Adolescent↗
PubMed1990

Morphological and physiological responses to aldosterone: time course and sodium dependence.

The time course and Na+ dependence of morphological responses to a physiological elevation of aldosterone were examined in the renal cortical collecting duct. Male Sprague-Dawley rats were adrenalectomized and given a basal replacement infusion of aldosterone and dexamethasone by osmotic minipump. The animals were given additional aldosterone by either intravenous infusion or by a second implanted osmotic minipump for either 5 h or 1, 3, 7, or 14 days. Animals were fed either a Na(+)-replete or a low-Na+ diet. After these treatments we conducted a morphometric analysis on kidneys processed for electron microscopy by standard techniques. Increased aldosterone induced detectable proliferation of the basolateral membrane of principal cells after 24 h. Basolateral membrane continued to increase rapidly through 3 days of exposure and thereafter at a modest rate. Cell area and the surface density of the basolateral membrane were also increased by aldosterone treatment. The morphological response to aldosterone was markedly inhibited by maintaining animals on a low-Na+ diet. Acute exposure to elevated aldosterone levels (5 h) increased K+ secretion by principal cells without alterations in basolateral membrane area. Chronic (greater than 24 h) exposure to aldosterone induces morphological adaptations that are accompanied by further elevations in K+ secretion.

Aldosterone↗
PubMed1988

Morphological heterogeneity of the rabbit collecting duct.

The localization of carbonic anhydrase by histochemistry, of Na-K-ATPase by immunocytochemistry and of rod-shaped intramembranous particles by freeze-fracture electron microscopy, was determined in the collecting duct of rabbits. In the cortical collecting duct (CCD), rod-shaped particles, which are abundant in intercalated cells were observed in both the apical and basolateral membrane of all intercalated cells examined. In the outer stripe of the outer medullary collecting duct (OMCDo) a high density of rod-shaped particles was found only in the apical membrane of intercalated cells. All cells of the inner stripe of the outer medullary collecting duct (OMCDi) had rod-shaped particles in the apical membrane but not in the basolateral membrane. As the collecting duct entered the inner medulla the density of rod-shaped particles decreased until they were virtually absent in the terminal segment. Na-K-ATPase, localized to the basolateral membrane, was more abundant in principal cells than in intercalated cells in the CCD. In the OMCDo, staining was equal in principal and intercalated cells. All cells of the OMCDi and the inner medullary collecting duct (IMCD) stained for Na-K-ATPase. Carbonic anhydrase in the CCD was localized to the cell membranes and cytoplasm of intercalated cells. Principal cells did not stain for carbonic anhydrase. A similar pattern was seen in the OMCDo. In the outer region of the OMCDi most cells did not stain for carbonic anhydrase, whereas in the inner region the apical and lateral membranes of all cells stained for carbonic anhydrase. Weak cytoplasmic staining was occasionally seen. A similar pattern was seen in the initial half of the IMCD, while the terminal half of the IMCD did not stain. In this study, the localization of enzymes and rod-shaped intramembranous particles associated with Na+, K+, and H+ transport shows both segmental and cellular heterogeneity, and correlates with the known transport properties of tubule segments. The distribution of these enzymes and rod-shaped intramembranous particles is different in rabbits and rats, and may explain some of the functional differences between homologous segments in these species.

Animals↗
PubMed1979

A micropuncture study of the renal handling of lithium.

Although clearance studies in man and experimental animals indicate that filtered lithium is reabsorbed primarily in the proximal tubule, it is unclear whether lithium is also reabsorbed in distal portions of the nephron. Micropuncture studies were, therefore, performed to determine the nephron sites involved in lithium transport during free flow. A method was established to estimate the concentration of lithium in nanoliter samples, using the Helium Glow photometer, which permitted the accurate measurement of lithium in tubular fluid samples over a range from 0.5--30.0 mM. Approximately 56% of filtered lithium and tubular fluid was reabsorbed at the end of the proximal convolution, while at the early distal tubule 75% of filtered lithium and water was reabsorbed. There was no change in net transepithelial movement of lithium beyond the loop of Henle. These data suggest that lithium transport is localized to the proximal tubule, including the pars recta. Lithium reabsorption does not occur in distal tubule or collecting duct. Beyond the early distal tubule net movement of lithium and sodium is dissociated.

Animals↗
PubMed1979

Differentiation of primary affective illness from situational, symptomatic, and secondary depressions.

Analysis of family history and antidepressant drug response variables of 100 "neurotic" depressives followed up prospectively over three to four years disclosed that primary depressions (unipolar and bipolar) could be distinguished from nonprimary cases by (1) the early occurrence of "pharmacological-hypomania;" (2) family history of bipolar illness; (3) family history for affective disorder in two or three consecutive generations, especially when "loaded." Although each of these variables alone occurred in only one fifth to one third of the primary group, they individually displayed better than 95% specificity for it. Thus, the confidence with which the diagnosis of primary affective illness could be made in the presence of any of these variables ranged from 88% to 100%. These findings argue for considering such nonsymptomatological variables for their potential in strengthening the phenomenologic diagnostic criteria for depressive illness.

Adjustment Disorders↗
PubMed1979

The clinical course of mesangial proliferative glomerulonephritis.

Patients with a pure mesangial proliferative glomerulonephritis may present with either hematuria, asymptomatic proteinuria, or nephrotic syndrome. For patients with hematuria, the clinical course is self-limited, and spontaneous resolution of recurrent episodes of macroscopic hematuria occurred in many of these patients. For patients with asymptomatic proteinuria, a spontaneous decrease in proteinuria occurred and none of these patients developed a progressive course. The clinical course of patients with nephrotic syndrome was similar to that usually observed in children and adults with pure minimal change lesions. A complete remission of the nephrotic syndrome occurred in most of these patients during treatment with prednisone and cyclophosphamide. Overall, the prognosis for the patients reported in this series was quite good.

Adolescent↗
PubMed1979

Dissociation of proximal tubular glucose and Na+ reabsorption by amphotericin B.

The effect of amphotericin B on glucose and Na+ transport was studied in the Necturus proximal tubule and in microvillus membrane vesicles isolated from the rabbit renal cortex. In the Necturus experiments, the rate constants for disappearance of radiolabeled glucose (kG) and mannitol (kM) from the tubular lumen were determined by stop-flow microperfusion. Saturability and Na+-dependence of glucose reabsorption was confirmed, since kG was reduced by raising intratubular glucose from 1 to 5 mM or by replacing intratubular Na+ with choline. Neither maneuver affected kM. Intratubular amphotericin B (10 microgram/ml), previously shown to stimulate active Na+ reabsorption in the Necturus proximal tubule, inhibited kG with no effect on kM. In the membrane vesicle preparation, amphotericin inhibited the uphill glucose uptake which results from imposing a NaCl gradient from outside to inside, but had no effect on glucose uptake in either the absence of Na+ or in the presence of Na+ when there was no Na+ gradient. Amphotericin B stimulated the uptake of Na+ by the vesicles. The observed dissociation of glucose and Na+ transport by amphotericin B is consistent with the concept that proximal tubular glucose reabsorption is energized by the luminal membrane Na+ gradient and is not directly linked to active Na+ transport per se.

Amphotericin B↗