kappa Chain joining segments and structural diversity of antibody combining sites.

Immunoglobulin kappa light chains are coded for by at least three distinct gene segments designated variable, joining, and constant. The joining gene codes for the 13 amino acid segment linking the variable and constant regions. This peptide includes the last amino acid (96) in the third complementarity-determining region and thus could introduce structural diversity. We have determined the light chain variable region sequences from three myeloma proteins with beta(1,6)galactan-binding specificity, bringing to six the number of light chains sequenced from proteins demonstrating this specificity. Five of these have isoleucine at position 96 and the sixth tryptophan. This substitution appears to be accommodated with no significant change in association constant for a beta(1,6)galactan hapten. Additionally, as many as nine substitutions are found in both light and heavy chain complementarity-determining regions between members of this group although only minimal variations in hapten binding affinity are observed. The isoleucine found at position 96 in five of the kappa chains could not be coded for by any of the joining gene nucleotide sequences previously observed and would require a novel nucleotide sequence at the recombination site between variable and joining genes to produce the observed protein structure. Alternatively, there may exist joining gene segments not yet detected.     

Allopurinol treatment and its effect on renal function in gout: a controlled study.

Fifty-nine patients with primary gout were treated with either a combination of colchicine and allopurinol or colchicine alone. Assessments of renal function over 2 years revealed a statistically significant fall of glomerular filtration rate an urine concentrating ability in those receiving only colchicine. The renal function of patients given allopurinol did not change. Treatment with allopurinol resulted ina significant reduction of ammonium excretion, a phenomenon which could not be readily explained. Urate clearance also declined during allopurinol treatment, and the impaired urate clearance associated with gout became more evident. The most important observation was that allopurinol retarded an apparent decline of renal function. Presumably this was achieved through its hypouricaemic effect and implies that the hyperuricaemia of gouty patients is deleterious to the kidneys.     

Heparinization in aortic surgery

A prospective study was conducted on 35 patients (25 males and 10 females) undergoing elective reconstructive aortic surgery to examine the heparin activity after a bolus dose of sodium heparin (100 U/kg) given five minutes prior to aortic cross clamping. Recording of heparin activity were made 15 minutes later, on release of the aortic clamp, at abdominal wound closure and hourly thereafter until minimal activity was reached. In 10 patients, protamine was used to reverse anticoagulation. These results were related to clinical parameters of age, renal function, plasma cholesterol, blood pressure, position of the aortic clamp and blood loss. High peak levels of heparin activity were more likely in patients with impaired renal function or high plasma cholesterol concentrations. Heparin activity was prolonged at therapeutic levels in patients with renal impairment, and in this group of patients the use of protamine was significantly increased as was the requirement for blood replacement.     

Effect of Chronic Alcohol Feeding on Hepatic Iron Status and Ferritin Uptake by Rat Hepatocytes

Alcohol abuse is known to cause disturbances to iron homeostasis in man and is associated with elevated serum ferritin levels. We have previously shown that ethanol metabolism in the rat hepatocyte is associated with an immediate reduction in ferritin uptake by this cell. In this study we have examined the effect of pair-feeding the Lieber-DeCarli liquid alcohol diet on ferritin uptake by rat hepatocytes. Rat liver ferritin was radiolabeled with ⁵⁹Fe in vivo and isolated by conventional techniques. Rats were pair-fed the Lieber-DeCarli liquid alcoholic diet for 4–6 weeks. Hepatocytes, isolated from their livers by collagenase perfusion, were incubated with [⁵⁹Fe]ferritin in L-15 medium at 37°C and 4° to measure ferritin uptake and binding. The in vitro effect of ethanol on these hepatocytes was also studied. Ferritin and iron parameters were measured in the sera and hepatocytes of these animals and a comparable group of normal chowfed rats. The rate of ferritin uptake by hepatocytes from alcohol-fed rats was significantly faster than that of their pair-fed controls (0.743 ± 0.061 vs. 0.540 ± 0.042 ng/min/10⁶ cells, p < 0.05). However, the rats on Lieber-DeCarli control diet exhibited a lower hepatocyte ferritin uptake rate than chow-fed animals (79.3 ± 8.1% of the control values, p < 0.01). In vitro incubation of cells in 100 mm ethanol resulted in less inhibition of ferritin uptake by hepatocytes from alcoholic rats than from their pair-fed controls (11 ± 7.1% inhibition vs. 43.6 ± 10.7% for controls, p < 0.05). Receptor-mediated binding of ferritin to hepatocytes showed a 61% increase in saturable binding capacity for alcoholic rats (15,820 ± 4950 molecules/cell vs. 9798 ± 3622, p= 0.05). The presence of ethanol in the medium did not affect ferritin binding significantly. Although there was no significant difference in the serum iron values between all three groups, transferrin concentrations were markedly elevated in the alcohol-fed rats, resulting in a much lower transferrin iron saturation than for the control animals. Because the corresponding serum values for the diet controls were intermediate between those for the alcohol-fed rats and the chow-fed animals, these findings may reflect dietary restriction by the liquid diet, which is exacerbated by the addition of alcohol. These findings suggest that there is increased iron uptake by the hepatocyte following chronic alcohol administration, which may be due to the increased ferritin receptors. This is supported by the observation that this alcohol treatment also causes a depletion of serum ferritin. However, the decreased iron content in the alcohol-fed rats indicate that this may be due to a response to changes in iron homeostasis by the hepatocyte and/or redistribution in the body.