Platelet-free calcium and vascular calcium uptake in ethanol-induced hypertensive rats.

This study examined the effect of moderate ethanol intake on systolic blood pressure, platelet cytosolic free calcium, aortic calcium, and rubidium-86 uptake in Wistar-Kyoto rats. Twelve Wistar-Kyoto rats, aged 6 weeks, were given 5% ethanol in drinking water the first week followed by 10% ethanol in drinking water for the next 6 weeks. Twelve control animals were given regular tap water. Systolic blood pressure in the ethanol-treated rats was significantly higher (p less than 0.05) than that in controls after 1 week and remained higher throughout the study. At 13 weeks of age, platelet cytosolic free calcium and calcium uptake by aortas were significantly higher (p less than 0.001) in ethanol-treated animals as compared with those in controls. Ethanol intake did not affect aortic ouabain-sensitive 86Rb uptake. The in vitro effect of ethanol on calcium-45 and 86Rb uptake was also investigated in aortas of untreated Wistar-Kyoto rats at 13 weeks of age. In vitro ethanol (2.5-20 mmols/l) did not significantly affect 45Ca and 86Rb uptake in rat aortas. The increases in systolic blood pressure, platelet cytosolic free calcium, and vascular calcium uptake suggest that increases in cytosolic free calcium and calcium uptake mechanisms are associated with ethanol-induced hypertension.

Comparison of patients with idiopathic calcium phosphate and calcium oxalate stones.

Our primary objective was to test the hypothesis that a defect in acidification is more common in patients who have idiopathic calcium phosphate kidney stones than in those whose stones are formed mainly of calcium oxalate. Additionally, other risk factors might differ for these 2 stone types. Urine pH was measured serially over 24 hours, and along with ammonium and titratable acid, it was measured before and serially after ingestion of ammonium chloride in 3 groups of subjects: 24 patients with predominantly calcium phosphate stones, 30 patients with calcium oxalate stones, and 15 health non-stone-formers. Twenty-six parameters potentially related to stone formation and acidification were assayed on urines collected over 24 hours, and 15 parameters on blood. The data base was a computerized list of 5900 analyses of stones from patients living in Newfoundland. Patients not known by their physician to have had urinary tract infection, anatomical abnormality, hyperparathyroidism, or renal tubular acidosis were asked to participate in the study. Differences between means were considered significant if p values were less than 0.05 for F by analysis of variance and also less than 0.01 by t-test. In all patients with calcium oxalate stones and all non-stone-formers, urine acidified to pH less than 5.25, but in 8 of the 23 phosphate stone formers who completed the ammonium chloride study urine failed to acidify to pH less than 5.25. As all 8 had normal values for venous pH, total CO2, and chloride, they were considered to have incomplete renal tubular acidosis (IRTA). The 8 phosphate stone formers with IRTA had greater mean values for urine pH on all 9 specimens collected serially over 24 hours (all means greater than 6.2), and after administration of ammonium chloride (p less than 0.01), as well as lower mean values for urine titratable acid excretion (p less than 0.01), both after administration of ammonium chloride and in 24-hour urine samples, compared with the remaining phosphate stone formers whose urine acidified and the oxalate and non-stone-forming control groups. Nearly all the phosphate stone formers had 1 or more risk factors for stone formation, but with frequencies not significantly higher than those found in the oxalate group. Hypercalciuria and hypocitruria were the commonest, but increased oxalate or urate also occurred. Thus, idiopathic calcium phosphate stone formation can be associated with 1 or more of several risk factors, and, with the possible exception of those with IRTA, treatment should be similar to that given to patients with calcium oxalate stones.

Lipids as endogenous Na,K-ATPase inhibitors in plasma of healthy individuals and in dialysis dependent patients.

We assayed plasma Na,K-ATPase inhibitory activity due to total lipids and lipid fractions. The effect of dialysis on the Na,K-ATPase inhibitory activity was also studied. Plasma lipid extracts from 11 healthy volunteers and 9 dialysis-dependent patients (pre and post dialysis) were separated into neutral lipids and phospholipids. Further fractionation was by thin layer chromatography. These lipid fractions were analyzed for Na,K-ATPase inhibitory activity by displacement of [3H]-ouabain from hog brain Na,K-ATPase. Total inhibitory activity was significantly increased (p less than 0.001) in the post-dialysis plasma compared to pre-dialysis plasma of the same patient group and to controls (482, 85 and 78 nmol/L respectively; means of the groups in digoxin equivalents). The major inhibitory activity was associated with non-esterified fatty acids with modest contributions from four other lipid fractions. Our results show that endogenous lipids are major plasma Na,K-ATPase inhibitors in vitro under these assay conditions.

Plasma endogenous digitalis-like factors in healthy individuals and in dialysis-dependent and kidney transplant patients.

Plasma digitalis-like factors (DLF), dehydroepiandrosterone sulfate (DHEAS) and cortisol were assayed in 20 healthy subjects, 22 dialysis dependent subjects and 30 patients with kidney transplants. DLF were assayed on plasma extracts by digoxin radioimmunoassay (RIA), and by Na,K-ATPase inhibition and [3H]-ouabain displacement using hogbrain Na,K-ATPase. Values for the 3 methods strongly intercorrelated (r = 0.99, p less than .001). Mean values for plasma DLF, assayed by all three methods, were significantly greater in dialysis dependent subjects, than in healthy subjects (p less than .0001). Mean plasma DLF values measured by digoxin RIA in renal transplant recipients, were significantly lower than in dialysis dependent subjects (p less than 0.0001) and higher than in healthy subjects. Plasma DLF values correlated inversely with creatinine clearance (p less than 0.01). Plasma DHEAS levels were significantly lower and contributed substantially less to digoxin antibody reactivity and ouabain displacement in dialysis subjects and in renal transplants compared with healthy subjects. There was no change in plasma immunoreactive DLF, DHEAS or cortisol measured before and after dialysis. DHEAS is a major digoxin like immunoreactive DLF and a minor Na,K-ATPase inhibitor in healthy subjects but makes only a minor contribution to DLF in dialysis and transplant subjects. We found the assays involving Na,K-ATPase inhibition and [3H]-ouabain displacement from Na,K-ATPase to be more sensitive for plasma DLF than the digoxin RIA, but because of the strong correlation between the methods, we suggest the RIA on plasma extracts can be used as a screening procedure.

Increased calcium uptake in vascular tissue by plasma of salt induced hypertensive Dahl rats.

Elevated intracellular free cytosolic calcium in vascular smooth muscle cells has been suggested in the pathophysiology of hypertension and circulating factors in the plasma have been implicated. To investigate the role of these factors on calcium homeostasis in salt induced hypertension, calcium uptake was measured in aortae of Sprague-Dawley rats by plasma derived from Dahl salt sensitive and resistant rats given high (8.0%) and low (0.4%) salt diets, respectively, for four weeks. Calcium uptake was also measured in aortae of Dahl rats on these diets. Calcium uptake in aortae and systolic blood pressure were higher (P less than 0.001) in Dahl salt sensitive rats given a high salt diet as compared to those on a low salt diet. Plasma from salt sensitive rats on high salt diet increased calcium uptake (P less than 0.001) in aortae of Sprague-Dawley rats. In contrast, no changes in calcium uptake and systolic blood pressure were observed in Dahl salt resistant rats. The parallel increase in systolic blood pressure and calcium uptake in Dahl salt sensitive rats on high salt diet suggests that increased intracellular free calcium may be involved in the pathophysiology of hypertension. The increased calcium uptake seems to reflect an abnormality in calcium handling by the vessels. These data also demonstrate that plasma from salt sensitive rats on high salt diet increases calcium uptake in aortic tissue.

Early detection of prostate cancer. Role of prostate-specific antigen.

Pressure to request prostate-specific antigen (PSA) tests for early detection of prostate cancer in middle-aged and older men is increasing. However, current scientific data suggest that such testing does more harm than good. Most professional groups do not advise routine screening for prostate cancer. This paper reviews the current status of PSA testing.

Muscle cramps and magnesium deficiency: case reports.

Magnesium deficiency is more common than is believed. This article discusses florid magnesium deficiency in two patients and the results of treatment. While neither case was difficult to diagnose, the severity of symptoms was unusual. Magnesium deficiency should always be included in the differential diagnosis of patients who present with persistent or severe muscle pain.

The role of vascular Na,K-ATPase activity in salt induced hypertension in Dahl rats.

The role of endogenous inhibitors of vascular Na,K-ATPase (NKA) activity in salt-induced hypertension was evaluated by examining the inhibition of 86Rb+ uptake in aortae of Sprague-Dawley (SD) rats by plasma derived from Dahl sensitive (DS) and resistant (DR) rats given high (8%) and low (0.4%) NaCl diet for four weeks. With 4 weeks of high salt diet DS rats demonstrated marked increase in systolic blood pressure. When compared to DR and DS rats on low salt diet, plasma from DR and DS rats on high salt diet had a stimulatory (not inhibitory) effect on NKA as measured by 86Rb+ uptake of SD rat aortae. As compared to DR rats plasma from DS rats on similar salt intakes had a stimulatory effect on NKA of SD rats. Aortae from the 4 groups of Dahl rats were also assayed for NKA activity. Total, ouabain-sensitive and ouabain-insensitive NKA activities were higher in DS rats as compared to DR rats on similar salt diet. Both DS and DR rats on high salt diet had higher NKA activity than on low salt diet. There was no evidence for a decrease in vascular sodium pump activity accompanying hypertension. Furthermore, high salt diet did not increase plasma Na,K-ATPase inhibitory activity in DS rats when hypertensive. These results suggest that NKA inhibition plays a minor role if any in hypertension of DS rats, in contrast to what has been hitherto believed.

Do we need another randomized controlled trial of folic acid alone?

As a public health strategy to help prevent neural tube defect-affected pregnancies, enriched flour and pasta in the United States and Canada are being fortified with folic acid, and women are being advised to take supplementary folic acid around the time of pregnancy to ensure an adequate intake. But in spite of the recently published results of a public health campaign in China, the burden of proof that folic acid alone is responsible for a decreased risk of these birth defects rests on the results of a randomized controlled trial conducted by the Medical Research Council of the United Kingdom. Supporting evidence comes primarily from studies that have shown a protective effect of multivitamins containing folic acid as one of many nutrients. Based on a striking and potentially hazardous type of non-compliance observed in an earlier study in which a participant took multiple vitamin doses simultaneously and a suggestion of similar incidents in the Medical Research Council study, we conclude that a further randomized controlled trial of the protective effect of folic acid alone may be necessary.

Fructose-induced hypertension, hypertriglyceridemia and elevated cytosolic calcium in rats: prevention by deuterium oxide.

We examined the effect of 5% deuterium oxide (D20) in drinking water on systolic blood pressure, platelet cytosolic free calcium, aortic calcium uptake and plasma insulin, glucose and triglycerides in rats with fructose-induced hypertension. Eighteen male Wistar-Kyoto (WKY) rats, age 8 weeks, were divided into 3 groups of 6 animals each. Animals in group I were given water; group II, 8% fructose and group III, 8% fructose + 5% D20 as their drinking water for the next 15 weeks. Systolic blood pressure in the fructose treated rats was significantly higher (p < 0.01) than in animals on water after 2 weeks and remained higher throughout the study. At 15 weeks, systolic blood pressure, platelet cytosolic calcium, aortic calcium uptake and plasma glucose, insulin and triglycerides were significantly higher (p < 0.01) in the fructose treated rats compared with rats from other groups. Deuterium oxide given together with fructose prevented development of high blood pressure and the associated increase in platelet cytosolic calcium, aortic calcium uptake and plasma triglycerides. D20 treatment did not prevent fructose induced increases in plasma insulin and glucose. The parallel increase in systolic blood pressure, cytosolic free calcium, and in vascular calcium uptake suggests that an increased cytosolic free calcium is involved in the pathophysiology of hypertension. D20 prevents this hypertension by normalizing cytosolic free calcium.

Can nutritional criteria help predict outcome in hospitalized patients?

The following nutritional criteria were evaluated for their usefulness in predicting outcome in a prospective study of 66 randomly selected hospitalized patients with a variety of diagnoses: total protein, albumin, and transferrin concentrations in serum, creatinine height index, weight height index, phenylalanine/tyrosine ratio (Phe/Tyr), concentration of branched-chain amino acids in serum, and ratio of essential to nonessential amino acids in serum. The cases were followed from admission to discharge, and were classified into the following three groups: 43 "well"; 14 with "complications" but recovered; and nine "dead". Statistical analysis (Scheffe's s-test) demonstrated the means of "well" and "dead" groups to be different for total protein, albumin, transferrin, and Phe/Tyr. In individual patients the nutritional criteria, even for those with fatal outcome, were poor indicators of outcome. These nutritional criteria are useful in identifying hospitalized groups that are at maximum risk (i.e., death), but are much less useful for individual patients.

Oral heparin normalizes blood pressure and elevated cytosolic calcium in hypertensive rats.

Increased calcium uptake in vascular tissue, leading to elevated cytosolic free calcium has been implicated in the pathophysiology of hypertension. This study examined the effect of oral heparin on systolic blood pressure, platelet cytosolic free calcium and aortic calcium uptake in spontaneously hypertensive and normotensive Wistar-Kyoto rats. Starting at age 12 weeks, each strain of rats were divided into 2 groups (6 animals in each group); the control group was placed on H2O (100%) and the experimental group was placed on H2O with heparin (0.5 mg sodium heparin/ml H2O) for a period of nine weeks. At 21 weeks, systolic blood pressure, platelet cytosolic free calcium and aortic calcium uptake were significantly higher in spontaneously hypertensive rats on water compared with spontaneously hypertensive rats on heparin and Wistar-Kyoto rats on water and on heparin. Oral heparin treatment normalized the elevated platelet cytosolic free calcium, aortic calcium uptake and systolic blood pressure in spontaneously hypertensive rats but had no effect on Wistar-Kyoto rats. Heparin also prevented onset of adverse renal vascular changes observed in spontaneously hypertensive rats. Oral heparin treatment did not cause abnormal hematological, biochemical or pathological changes in rats.

Heart-lung protection from ischemic injury during 8 hour hypothermic preservation.

Optimal techniques of heart-lung preservation are yet to be defined. The aim of this study was to develop, in a canine model, a method of heart-lung preservation which would permit distant procurement of the organs. The animals were divided into 2 groups. In the experimental group (N = 6) the method of preservation consisted of cold cardioplegic arrest of the heart with St. Thomas' Hospital solution containing superoxide dismutase, catalase and deferoxamine, followed by cold pulmonary artery flush with modified Euro-Collins solution to which prostaglandin E1, superoxide dismutase, catalase, deferoxamine and Dextran 40 were added. Following harvesting, the heart-lung block was stored for 8 hours in cold (4 degrees C) Euro-Collins solution containing superoxide dismutase, catalase, deferoxamine, lactobionic acid, raffinose, mannitol, Dextran 40, magnesium sulfate, insulin and penicillin. In the control group (n = 6), the heart-lung block underwent the same treatment as the experimental group except that lactobionic acid, raffinose and insulin were omitted from the storage solution, and that oxygen radical scavengers were excluded from the cardioplegic, pneumoplegic and storage solutions. Histologic and electron microscopic examinations of heart-lung specimens taken before and after 8 hours cold storage of the organs suggested that our preservation technique may be effective in preventing ischemia-induced injury.