Glucocorticoids regulate Na+/H+ exchange expression and activity in region- and tissue-specific manner

Na+/H+ exchangers (NHEs) are integral membrane proteins that exchange Na+ for H+ across membranes. Four isoforms have been cloned (NHE-1-4). NHE-3 localizes to the apical domain, and its expression is increased in dexamethasone-treated rats by Northern analysis. This stimulatory effect on expression is region and tissue specific, being present in ileum and proximal colon, but not in jejunum, distal colon, or kidney. The increase in transcript expression in ileum correlates with an increase in protein expression by immunoblotting. Changes in apical Na+/H+ exchange activity, as measured by 22Na uptake into brush-border membrane vesicles, correlate with expression differences, with significant increases observed in ileum and proximal colon. In situ hybridization showed NHE-3 mRNA only in villus and absorptive cells of control rats, the pattern not being altered by dexamethasone treatment. This suggests that dexamethasone does not increase expression by inducing crypt cells to express NHE-3 prematurely. We conclude that glucocorticoids selectively increase intestinal NHE-3 activity in a region-specific manner and that this effect also appears to be tissue specific.

Inhibition of Ca2+ entry by Ca2+ overloading of intracellular Ca2+ stores in human platelets

1. This study examined the effect of overloading human platelet intracellular Ca2+ stores on the rate of agonist-evoked external Ca2+ entry. To overload the Ca2+ stores (presumably dense tubules), external Na(+)-dependent Ca2+ efflux via Na(+)-Ca2+ exchange was inhibited by pretreating the cells with ouabain or Na(+)-free medium. Ca2+ regulation was then examined after exposure to thrombin, ADP and thapsigargin. Cytosolic free Ca2+ levels were monitored using the fluorescent probe fura-2 and external Ca2+ influx was assessed by the rates of extracellular Mn2+ or 45Ca2+ uptake. 2. Both ouabain and Na(+)-free pretreatments caused a slight increase in the resting cytosolic free Ca2+. 3. In 1 mM Ca(2+)-containing medium, Ca(2+)-overloaded platelets showed similar thrombin-evoked cytosolic free Ca2+ responses to those of control platelets. However, in Ca(2+)-free medium, they showed substantially greater thrombin-evoked cytosolic free Ca2+ responses than control platelets. Moreover, increased thrombin-evoked Ca2+ mobilization from Ca2+ storage sites was accompanied by a diminished rate of thrombin-evoked external Ca2+ entry. 4. Similar reductions in the rate of external Ca2+ entry were observed after treatment with ADP and thapsigargin. 5. Protein kinase C inhibitors (calphostin C and staurosporine) failed to reverse the effect of ouabain pretreatment on thrombin-induced changes in the cytosolic free Ca2+ response. 6. Inositol 1,4,5-trisphosphate profiles in ouabain-treated and non-treated platelets were not significantly different. 7. These data indicate that increased Ca2+ in the dense tubules is associated with diminished agonist-evoked external Ca2+ influx.

Obstructive jaundice due to compression of the common hepatic duct by right hepatic artery--a case associated with the absence of the lateral segment of the left hepatic lobe

Various benign and malignant conditions can cause biliary obstruction. We present a rare case of obstructive jaundice due to the compression of the common hepatic duct by the anteriorly overriding right hepatic artery. This case was also associated with the absence of the lateral segment of the left hepatic lobe. The patient was a 39 year-old housewife with a 4-day history of jaundice and occasional febrile sensation. An abdominal computed tomography showed absence of the lateral segment of the left hepatic lobe and a percutaneous transhepatic cholangiography showed a band-like filling defect of 2 mm width at the level of the upper common hepatic duct. The anteriorly overriding right hepatic artery compressing the common hepatic duct and the absence of the lateral segment of the left hepatic lobe were confirmed by operation.

The luminance-response function of the dark-adapted rabbit electroretinogram

The Naka-Rushton equation of the form, R = Rmax I(n)/(I(n)+Kn), has been used to describe the b-wave luminance-response function of the scotopic electroretinogram. Rmax is the asymptotic value of the b-wave amplitude as a function of stimulus luminance I, K is the luminance that produces a b-wave amplitude that is one-half Rmax, and n is a dimensionless constant that controls the slope of the function. These three parameters are often used in research laboratories, since it can show selective changes in each parameter. The present study describes these parameters (Rmax = 354 +/- 28 uV, n = 0.80 +/- 0.06, log K = -2.26 +/- 0.15 log cd. sec/m2) and the values obtained from the derivative analysis of Naka-Rushton equation (Anastasi et al) in 20 normal pigmented rabbit eyes. However, Naka-Rushton equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase appears in the function.

Blood pressure inversely correlates with thrombin-evoked calcium rise in platelets

Earlier investigations showed a positive correlation between basal cytosolic free calcium in human platelets and blood pressure; however, recent studies have failed to show this relation. We undertook the present work to examine which platelet cytosolic calcium parameters (namely, cytosolic calcium in resting or stimulated states in calcium-containing and calcium-free media) present the least variability and best correlation with blood pressure. We studied 17 healthy white men on three different occasions separated by 1- and 4-week intervals. Their manual and ambulatory automated 24-hour blood pressure measurements were correlated with cytosolic calcium in resting and stimulated (thrombin-treated) fura 2-loaded platelets. The following cytosolic calcium parameters were measured in 1 mmol/L calcium and calcium-free media: basal cytosolic calcium, peak thrombin-evoked cytosolic calcium, and post-transient cytosolic calcium 5 minutes after thrombin treatment. The highest and lowest coefficients of variation were respectively shown by the basal cytosolic calcium (22.8%) and peak thrombin-evoked cytosolic calcium (10.1%) in calcium medium. Basal cytosolic calcium did not correlate with any of the blood pressure parameters. Of the cytosolic calcium parameters, peak thrombin-evoked cytosolic calcium in calcium medium demonstrated consistent (negative) correlations with blood pressure, with better correlations shown with diastolic than systolic blood pressure of both automated and manual blood pressure readings. Peak thrombin-evoked cytosolic calcium in calcium medium showed similar correlations with nighttime and daytime automated blood pressure measurements. There were no correlations between peak thrombin-evoked cytosolic calcium in calcium-free medium and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in platelet calcium regulation between African Americans and Caucasians: implications for the predisposition of African Americans to essential hypertension

OBJECTIVE

To study differences in cytosolic free calcium regulation between African Americans and Caucasians, using platelets as a model for studying cellular physiology.

DESIGN

Platelet calcium regulation in apparently healthy African American and Caucasian males was examined.

METHODS

Using fura-2, calcium influx and cytosolic calcium extrusion were monitored after treatment with thapsigargin, an inhibitor of the Ca-ATPase in the dense tubular membrane system.

RESULTS

Compared with Caucasians, platelets from African Americans demonstrated a higher calcium influx into the cytosol (from the external medium and dense tubular membrane system), as well as enhanced calcium extrusion from the cytosol.

CONCLUSIONS

Such findings indicate that platelets from African Americans have increased intracellular calcium stores or increased cellular calcium turnover, or both. If these racial differences involve other cells, such as vascular smooth muscle cells, they could underlie the predisposition of African Americans to essential hypertension.

Analysis of regional differences of p53 mutation in advanced gastric carcinoma: relation to heterogeneous differentiation and invasiveness

In order to examine the correlation of p53 mutation with heterogeneous histological differentiation and invasiveness of gastric carcinoma, we analyzed 46 areas (three to six per case) that were different histologically and anatomically in 12 advanced gastric carcinomas, shown previously to be positive for p53 mutation, using immunohistochemical, polymerase chain reaction-single strand conformation polymorphism, and direct DNA sequencing analyses. DNA derived from different sites in nine cases had the same pattern of p53 mutation, even in cases manifesting heterogeneous histology within a single tumor. Site difference of the p53 mutation was found in three cases: two showed no mutation in superficial tumor areas but presence of mutation in deep-infiltrating areas. In contrast, one case contained a mutation in the superficial area but not in the deep-infiltrating area. These results suggest that in most cases, tumor cells forming a single advanced gastric carcinoma, even though they may present a heterogeneous histology and deep invasion, seem to be derived from the same cellular clone.

Primary choriocarcinoma of the urinary bladder--a case report

We report a primary choriocarcinoma of the urinary bladder in a 63-year-old man who presented with painless hematuria. He was diagnosed as having an invasive carcinoma and underwent a total cystectomy. The tumor was diffusely hemorrhagic and occupied the dome of the bladder. Histologically, it consisted of cyto-and syncytiotrophoblasts with extensive hemorrhage. No coexisting transitional cell carcinoma component was present. By immunohistochemistry, the tumor expressed beta-hCG and low-molecular weight cytokeratin intensely while it was negative for CEA or EMA. The post-cystectomy serum beta-hCG was 237mlU/ml, and decreased later. The pertinent literature is reviewed and diagnostic criteria are discussed.

Platelet sodium-hydrogen antiport in obese and diabetic black women

In this investigation we correlated platelet Na-H antiport parameters with blood pressure and serum lipids in a sample population of non-insulin-dependent diabetic obese, nondiabetic obese, and nondiabetic nonobese black women. Parameters of the Na-H antiport were examined in aspirin-treated platelets. These parameters were not altered in resting or in thrombin-stimulated platelets of diabetic patients. The activity index of platelet Na-H antiport after thrombin stimulation was positively correlated with the blood pressure (systolic blood pressure, r = 0.5320 and p = 0.0001; diastolic blood pressure, r = 0.5123 and p = 0.0017). Lower high density lipoprotein cholesterol levels were associated with an alkaline shift in the cytosolic pH set point for activation of the Na-H antiport. Highly significant correlations were also observed between the total cholesterol/high density lipoprotein cholesterol ratio and the cytosolic pH set point for activation of the Na-H antiport. These correlations were independent of diabetes or the body mass index. Together, these observations indicate that parameters of platelet Na-H antiport are altered with an increase in blood pressure and a decrease in serum high density lipoprotein cholesterol.

Progressive atypical peripheral neuropathy following nephrectomy in a patient with renal cell carcinoma

Peripheral neuropathy or amyotropic lateral sclerosis can be associated with renal cell carcinoma. We report a 63-year-old male patient with renal cell carcinoma who developed an atypical, progressive neuropathy after nephrectomy.

Cytogenetic analysis of meningiomas

Cytogenetic analysis of 4 cases of meningiomas from 3 male and 1 female patients is reported. One of male patients suffered from neurofibromatosis type 2. Histologically, the meningiomas were meningotheliomatous (1), transitional (2), and psammomatous (1). Chromosomal abnormalities were found in all cases with a karyotype 45,XY,-22, 45,XY,-16, 45,XX,-2, and 45,XY,t (15p;22q), respectively. Monosomy of chromosome 22 was detected only in the patient with neurofibromatosis type 2. These cytogenetic analysis demonstrates that variable clonal karyotype aberrations exist in meningiomas.