Failure to Replicate Depletion of Self-Control

The limited resource or strength model of self-control posits that the use of self-regulatory resources leads to depletion and poorer performance on subsequent self-control tasks. We conducted four studies (two with community samples, two with young adult samples) utilizing a frequently used depletion procedure (crossing out letters protocol) and the two most frequently used dependent measures of self-control (handgrip perseverance and modified Stroop). In each study, participants completed a baseline self-control measure, a depletion or control task (randomized), and then the same measure of self-control a second time. There was no evidence for significant depletion effects in any of these four studies. The null results obtained in four attempts to replicate using strong methodological approaches may indicate that depletion has more limited effects than implied by prior publications. We encourage further efforts to replicate depletion (particularly among community samples) with full disclosure of positive and negative results.     

A Magnesium Based Phosphate Binder Reduces Vascular Calcification without Affecting Bone in Chronic Renal Failure Rats

The alternative phosphate binder calcium acetate/magnesium carbonate (CaMg) effectively reduces hyperphosphatemia, the most important inducer of vascular calcification, in chronic renal failure (CRF). In this study, the effect of low dose CaMg on vascular calcification and possible effects of CaMg on bone turnover, a persistent clinical controversy, were evaluated in chronic renal failure rats. Adenine-induced CRF rats were treated daily with 185 mg/kg CaMg or vehicle for 5 weeks. The aortic calcium content and area% calcification were measured to evaluate the effect of CaMg. To study the effect of CaMg on bone remodeling, rats underwent 5/6th nephrectomy combined with either a normal phosphorus diet or a high phosphorus diet to differentiate between possible bone effects resulting from either CaMg-induced phosphate deficiency or a direct effect of Mg. Vehicle or CaMg was administered at doses of 185 and 375 mg/kg/day for 8 weeks. Bone histomorphometry was performed. Aortic calcium content was significantly reduced by 185 mg/kg/day CaMg. CaMg ameliorated features of hyperparathyroid bone disease. In CRF rats on a normal phosphorus diet, the highest CaMg dose caused an increase in osteoid area due to phosphate depletion. The high phosphorus diet combined with the highest CaMg dose prevented the phosphate depletion and thus the rise in osteoid area. CaMg had no effect on osteoblast/osteoclast or dynamic bone parameters, and did not alter bone Mg levels. CaMg at doses that reduce vascular calcification did not show any harmful effect on bone turnover.     

Tetracycline Poisoning in Renal Failure

Seven cases are reported in which drugs of the tetracycline group produced a fall in the glomerular filtration rate. In six patients there was a primary underlying renal disease and renal impairment. All seven patients were made seriously ill by the antibiotic. Two patients required immediate haemodialysis; one died and the other continued on dialysis until transplanted. Another patient initially responded to intravenous fluids and protein restriction but his renal function deteriorated and four months later he began maintenance haemodialysis. Three patients required peritoneal dialysis. The seventh patient responded satisfactorily to conservative management. The medical and medicolegal complications arising from the use of tetracycline in patients with renal disease are discussed. Yet another plea is made that drugs of the tetracycline group other than doxycycline should not be given to patients with chronic renal failure.     

Renal Failure in Acute Pancreatitis

In three patients with acute pancreatitis complicated by renal failure recovery followed dialysis and treatment of associated complications. The records of cases of pancreatitis treated at Addenbrooke''s Hospital, Cambridge, suggest that renal failure is a grave and not infrequent complication of acute pancreatitis.     

Hypergastrinaemia in Chronic Renal Failure

Fasting serum gastrin was measured by radioimmunoassay in 89 patients with chronic renal failure. When the serum creatinine level was used as an index of the degree of renal impairment serum gastrin rose proportionately with the degree of renal failure. Haemodialysis did not significantly alter serum gastrin levels but renal transplantation tended to return them towards normal. This study indicates that the kidney has a role in the degradation of gastrin.     

Pharmacodynamics of Propranolol in Renal Failure

The pharmacodynamics of propranolol were studied in patients with renal functional impairment. ¹⁴C-labelled propranolol was given either intravenously or by mouth and the disappearance rates of propranolol, 4-hydroxypropranolol, and total radioactive metabolites measured. The renal clearance of total radioactive compounds is directly related to renal function. The half-life of total radioactivity is greatly lengthened in the presence of severe renal failure while the half-lives of the pharmacologically active propranolol and 4-hydroxymetabolite are slightly reduced. There is a suggestion that the absorption of propranolol is delayed in renal failure. No known pharmacological action or side effects from the other metabolic products of propranolol have been recognized. There is still too little well-documented evidence concerning the beta-blocking activity of the unidentified major metabolites of propranolol to suggest any alteration in the dosage regimen used in renal failure.     

Late Failure in Cadaveric Renal Allografts

Sixteen patients with renal cadaveric allografts who have survived for one year or longer are reported. The patients were analyzed from the standpoint of incidence, quantity and course of proteinuria in relation to renal function and the nature of the original disease.This analysis shows that proteinuria is progressive and is accompanied by a decline in renal function when the original disease is of an immune nature. This was not so in patients with non-immune original disease. These findings suggest that recurrence of original disease plays an important role in late failure of cadaveric renal allografts.