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Immunization with purified idiotypic IgM derived from the BCL1 lymphoma generates CD4-positive T cells which proliferate specifically in response to idiotypic antigen expressed at the surface of the BCL1 tumor cells. These T cells have been hybridized and two cloned hybridomas have been used to study the molecular nature of the idiotypic antigen recognized. Endogenous presentation of idiotype by the B cells generated IL-2 from the T-cell hybridomas, as measured by a CTLL response. Presentation was inhibited in a dose-dependent manner by chloroquine or ammonium chloride, both of which affect proteolytic degradation of antigen in the endosomes. Similar results were obtained with inhibitors of metabolism or protein synthesis. However, none of these reagents affected expression of idiotypic IgM at the cell surface under the conditions used, indicating that whole IgM is not interacting directly with the T-cell receptor. Interaction between the presenting B cells and T-cell hybridomas was inhibited by anti-CD4 and, in one case, by a monoclonal antibody directed against a determinant in the I-Ed region of the MHC Class II. Inhibition also occurred with antibodies against IgM, either anti-constant region or anti-idiotype, and the univalent Fab' gamma fragment was an effective inhibitor. These data indicate that the B cell constitutively presents its endogenous idiotypic immunoglobulin to CD4-positive T cells following endocytosis from the surface, proteolytic degradation, and interaction with MHC Class II molecules. This endogenous pathway is perturbed by binding of exogenous anti-immunoglobulin antibody, perhaps mimicking what might occur when surface immunoglobulin encounters antigen.

A study is reported of the prevalence, nature and possible aetiology of the hyperlipidaemia found in a group of 74 patients receiving maintenance dialysis. Sixty patients were receiving haemodialysis and 14 peritoneal dialysis. Sixty-four per cent of the male and 83% of the female patients had a lipoprotein abnormality which was predominantly of the Type IV pattern, probably due to a combination of increased hepatic triglyceride synthesis and diminished peripheral clearance.

Plasma concentrations of calcium fractions, proteins, phosphate and magnesium were measured before, during and after cardiopulmonary bypass in 15 patients undergoing cardiac surgery. When calcium chloride was added to a pump priming solution which contained little or no blood, the concentrations of all calcium fractions were significantly greater after bypass than before, with a mean ionized calcium concentration of 1.52 mmol litre-1 plasma water, 30 min after completion of bypass. This iatrogenic hypercalcaemia was increased significantly by the administration of more than 10 mg kg-1 calcium chloride in the first 30 min after bypass. Other plasma constituents showed the dilutional effect of the pump prime during bypass and only the magnesium concentration failed to return towards normal values after operation.

Hyperlipidaemia is a characteristic feature not only of the nephrotic syndrome but also of chronic renal disease without the features of that syndrome. There is evidence for disordered lipid metabolism in patients with chronic renal disease. In these patients the disordered lipid metabolism, the precise cause of which is unknown, is characterised by hypertriglyceridaemia, the aetiology of which is probably multifactorial. Hyperlipidaemia is an important potential risk factor in the aetiology of cardiovascular disease, which may be a leading cause of death in patients undergoing long-term maintenance haemodialysis therapy.

Serum-25-hydroxy-vitamin-D (25 OHD) concentration has been measured in 106 patients with untreated parenchymal and cholestatic liver disease. Low mean values were found in groups of patients with alcoholic hepatitis and cirrhosis, non-cirrhotic active chronic hepatitis, lupoid and cryptogenic cirrhosis, symptomatic primary biliary cirrhosis, and acute and chronic biliary disease. In a group of patients with presymptomatic biliary cirrhosis the mean value was not significantly different from normal. It is concluded that in the presence of significant parenchymal or cholestatic liver disease serum-25-OHD concentrations are usually low. The mechanisms for the reduction remain to be clarified, but low serum-25-OHD values may play a contributory role in the aetiology of osteomalacia in chronic liver disease.

Four patients who had been on regular haemodialysis for periods of 3 1/2 to 7 years became hypophosphataemic with plasma-phosphate concentrations of 2.5 mg/dl or less before dialysis. None of them had been taking oral phosphate-binders for 2 years or more. Histologically all the patients had an excess of osteoid on bone biopsy. Intestinal absorption of phosphate and calcium was impaired, despite normal or high serum-25-hydroxycholecaliferol concentrations. Treatment with oral dihydrotachysterol resulted in corrections of the phosphate malabsorption and increases in plasma-phosphate concentration. The initial low plasma-phosphate values in these patients before dialysis probably reflected a state of phosphate depletion caused by the combination of malabsorption, loss during dialysis, and a low dietary intake.

The prognostic value of initial and sequential determinations of quantitative bacterial concentrations, leukocytes, glucose, lactate, lactic acid dehydrogenase, and creatine phosphokinase in CSF was examined in rabbits with experimental pneumococcal meningitis while they were receiving equivalent, rapidly bactericidal antibiotic therapy. The following mean CSF variables correlated with death due to meningitis: (1) an early (day 1) high bacterial titer and lactate concentration with simultaneous low leukocyte count and glucose level and (2) late (day 3) elevated lactate and lactic acid dehydrogenase levels and leukocyte count. A high concentration of bacteria inoculated into the CSF and a high plasma glucose level also adversely influenced prognosis. Careful analysis of these variables may identify high-risk patients with pneumococcal meningitis and ultimately may be useful in gauging the therapeutic response.

The muscle weakness that frequently accompanies osteomalacia and rickets may arise from a variety of causes. Particularly in patients with muscle weakness, identification of the metabolic disorder is important, since effective treatment is often possible.

A scheme is advanced whereby plasma-lipoproteins form an integrated controlled pathway for storage of energy as triglyceride. The importance of insulin within this system is indicated and the consequence of possible errors considered. Changes secondary to organ disease are found to fit within the proposed pathway. Although many refinements remain to be added, this hypothesis seems to form a plausible framework within which lipoprotein abnormality and the underlying condition may be better understood and thereby treated.

The biochemical changes observed in a patient with adult-onset hypophosphataemic osteomalacia after three weeks treatment with 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) followed by dihydrotachysterol (DHT) are reported. The treatment with 1,25-(OH)2D3 resulted in restoration of intestinal phosphate absorption to normal with a small rise in plasma phosphate concentration; there was no significant change in tubular reabsorption of phosphate. The tubular reabsorption of bicarbonate, which was initially low, returned almost into the normal range with normalisation of plasma bicarbonate concentration. Aminoaciduria decreased. There were no changes in plasma or urinary calcium but immunoreactive parathyroid hormone (i-PTH) which was initially elevated fell but still remained above the normal range. These changes were maintained after replacing the 1,25-(OH)2D3 treatment with dihydrotachysterol (DHT).

A study is reported of the effects of both pre- and post-dialysis serum and some of the known uraemic metabolites on parathyroid extract-induced bone resorption using an in vitro organ culture system. Serum from uraemic patients prior to haemodialysis was shown to inhibit the action of parathyroid hormone on bone and this inhibitory effect was not present after dialysis. Some of the uraemic metabolites studied and also phosphate exerted an inhibitory effect but the metabolites caused their inhibition at higher concentrations than those which are known to occur in uraemic patients. It is concluded that if uraemic metabolites play a role in vivo then it is probably due to a cumulative phenomenon.

An oral dose of 0.5 microgram of 1,25-dihydroxycholecalciferol (1,25-[OH]2D3) and 4 g of calcium carbonate was given daily to two dialysed patients and three undialysed patients in chronic renal failure with renal osteodystrophy. Treatment was given for 4-16 months. Intestinal calcium absorption became normal in all five patients. Plasma alkaline phosphatase, hydroxyproline, and immunoreactive parathyroid hormone were considerably reduced in all of the patients and in four of them these values were restored to normal. Bone histology was improved in all patients after treatment with 1,25-(OH)2D3. As well as a dramatic improvement in bone mineralisation, there was remodeling of trabecular architecture and a decrease in fibrosis in patients with initial parathyroid overactivity.

Four of the eight patients studied were vitamin D replete and 4 vitamin D depleted as judged by serum 25-hydroxy vitamin D (25-OHD) concentration. Three of the 4 vitamin D depleted patients (including 2 with histological osteomalacia) formed radioactive 1,25-dihydroxycholecalciferol. One of the four vitamin D replete patients formed 1,25-dihydroxycholecalciferol but all formed 24,25-dihydroxycholecalciferol. This study suggests that patients with liver disease form dihydroxy vitamin D metabolites in an appropriate manner.

A competitive protein binding assay for serum 25-hydroxyvitamin D is described in which normal human serum is used as the source of binding protein. A serum sample is extracted with diethyl ether/methanol and then chromatographed using silica gel. Validation of the method is reported. Silica gel chromatography is compared with LH20 chromatography. The method is also compared with extraction techniques using diethyl ether and ethanol without subsequent chromatography. It is concluded that chromatography with either silica gel or LH20 is essential. The non-chromatographic methods investigated, in addition to giving much higher values than chromatographic methods, did not meet validation requirements with respect to accuracy and behaviour of samples on dilution.

Endogenous very low density lipoprotein triglyceride (VLDL-TG) production rate has been studied in 13 patients with chronic renal failure who were not on dialysis treatment. In these patients the VLDL-TG plasma concentration was significanlty raised when compared with the control group; the fractional turnover rate was reduced but the absolute turnover rate was increased. The results suggest that increased hepatic production of VLDL-TG is a contributory factor to the hypertriglyceridaemia of chronic renal failure.

In the past decade, aluminum has been recognized as a toxic metal in patients with chronic renal failure. It is, however, possible that other trace metals, such as nickel, may also have toxic actions in these patients. The plasma concentration of a metal, such as aluminum or nickel, may not provide a valid index of either tissue content or total body burden. In the study reported here, the aluminum and nickel content of lymphocytes was measured and compared with plasma concentrations in normal controls and patients with chronic renal failure. The findings suggest that lymphocytes may be of value as a nucleated 'tissue' for the assessment of trace metal status.

The supplementation of replacement solutions used during plasma exchange with calcium gluconate prevents hypocalcaemic symptoms.

Plasma calcium and magnesium fractions were measured in 51 patients with either hepatocellular or biliary disease. The fractions were found to be only minimally deranged. Plasma albumin correlated with total calcium and with the protein bound and ionized fractions. Abnormalities of plasma calcium or magnesium fractions are unlikely to play a role in the pathogenesis of the osteomalacia seen in chronic biliary disease.

In a group of thirty-six non-housebound normal people aged 70 to 88 years living independently in their homes, mean serum-25-hydroxyvitamin-D (+/- 1 S.D.) was 8-62 +/- 3-08 ng/ml in midwinter and had risen to 14-13 +/- 4-90 ng/ml the following September. These values were lower and the seasonal variation was less than previously found in healthy young British adults.

Plasma hydroxyproline fractions were measured in 17 normal subjects and in 54 patients on maintenance haemodialysis therapy (MHT) with various degrees of dialysis osteodystrophy. On the basis of both radiological and histological findings these patients were divided into three groups: radiologically normal, histologically normal and those with osteitis fibrosa. The mean total plasma hydroxyproline concentrations were significantly elevated in all groups of MHT patients. However, these increases were mainly due to peptide-bound and free hydroxyproline fractions. The highest values for these two fractions were found in patients with osteitis fibrosa. The free to peptide-bound hydroxyproline ratio was not significantly altered in the majority of patients on dialysis; the mean ratio was significantly lower in patients with osteitis fibrosa when compared with patients with no histological evidence of bone disease. This finding would suggest that there is no inhibition of hydroxyproline catabolism in patients on haemodialysis and the measurements of both free and peptide-bound hydroxyproline were equally sensitive in identifying patients with osteitis fibrosa.

Binding of aluminum to human serum albumin and transferrin was investigated using a competitive binding assay incorporating a cation exchange resin, chelex. Both albumin and transferrin were found to produce linear Scatchard plots of aluminum binding data over the aluminum and protein concentration ranges found in humans. Binding constants measured for albumin and transferrin were 1.96 and 0.515 microM, respectively.

Phosphate metabolism was investigated in 26 patients with a spectrum of liver diseases and mean fasting plasma phosphate concentrations were in the low normal range. A standard oral load of phosphate was used to test absorption and was subnormal in the majority of patients with large bile-duct obstruction and alcoholic liver disease. Subnormal results were also seen in patients with primary biliary cirrhosis and cirrhosis secondary to chronic active hepatitis. These abnormalities appeared to be related to vitamin-D deficiency. Tubular reabsorption of phosohate was markedly reduced in 3 of 14 patients. The therapeutic implications of phosphate status in liver disease are important.