Radioimmunoassay for serum apolipoprotein D, an atypical apolipoprotein: validation and clinical application.

Apolipoprotein D (apoD) is an atypical apolipoprotein in terms of its structure, synthesis and probable function. It is the most abundant protein in breast cyst fluids of patients suffering from macrocystic disease of the breast, a disease associated with an increased risk of developing breast cancer. We have developed and optimized a competitive radioimmunoassay for the measurement of apoD in human serum. The assay uses a solid phase separation method and with a 4 h incubation period, it can be completed in a single working day. The within and between run coefficients of variation were < 8.5% and < 12.2%, respectively, and quantitative recovery of apoD was obtained over the range 250-5000 micrograms/L. There was no difference in the serum concentrations of apoD between female controls, patients with benign breast disease and early breast cancer. However, serum apoD was significantly lower in breast cancer patients with bone metastasis.

Apolipoprotein E genotypes and serum lipid levels in Alzheimer's disease and multi-infarct dementia.

OBJECTIVE: Assessment of apolipoprotein E genotype, serum cholesterol, triglycerides, high density lipoprotein-cholesterol and low density lipoprotein-cholesterol levels in different types of dementia. SUBJECTS: 102 consecutive referrals to an old age psychiatry service based at Manchester were classified according to clinical criteria based on ICD 10. RESULTS: Thirty-seven were considered to have Alzheimer's disease, 16 multi-infarct dementia and 33 to be free from dementia. Sixteen patients, in whom a definitive diagnosis could not be reached or sufficient information was not available, were excluded from the study. There was an increase in the prevalence of the Apo E4 allele in both Alzheimer's disease (chi 2 = 3.82, p < 0.05) and multi-infarct dementia (chi 2 = 1.93, p < 0. = 0.16) by Wald tests compared to individuals without dementia. The increased prevalence of the E4 Allele in multi-infarct dementia was not related to serum lipid levels. CONCLUSION: The hypothesis that the onset of multi-infarct dementia may be precipitated by E4's mediation of higher serum cholesterol levels is not supported by the present study.

The inter-relationship of factor VII and its activity state with plasma lipids in healthy male adults.

A close inter-relationship between raised factor VII clotting activity and elevated blood lipids, particularly serum triglycerides, is well established. A study of factor VII, its activation state and of plasma lipids has been undertaken in two groups of healthy middle-aged males to elucidate this mechanism. A control group with normal factor VII levels were closely matched for age and body-mass index with a second group with elevated levels. Factor VII assays, using rabbit and bovine thromboplastin and a factor VII Ag method, were employed. Triglycerides correlated with the rabbit factor VII thromboplastin assay and factor VII Ag (P < 0.05) but not with the bovine thromboplastin method. Higher HDL-cholesterol and apolipoprotein A-I levels were found in subjects with increased factor VII (P < 0.001) and appeared to be due to differences in alcohol consumption. Cholesterol levels were significantly higher with elevated factor VII. Differential testing suggests that higher factor VII is predominantly mediated through a rise in total VII, rather than an increase in its activity state.

The effect of renal failure and haemodialysis on the concentration of free apolipoprotein A-1 in serum and the implications for the catabolism of high-density lipoproteins.

Free apolipoprotein A-1 (free A-1) was measured by quantitative crossed immunoelectrophoresis in 43 patients with severe chronic renal failure. The free A-1 concentrations in these patients were higher than in 28 healthy subjects irrespective of whether they where receiving haemodialysis or conservative treatment. A close correlation was found between serum concentration of free A-1 and creatinine in patients with varying degrees of chronic renal failure (r = 0.717, p less than 0.001). In three patients who received renal transplants serial measurements of free A-1 showed a decrease to normal levels within two days post-operatively. These findings suggest a relationship between the serum concentration of free A-1 and glomerular filtration. In conjunction with the report implicating the kidney as the major site of catabolism of Apo A-1 in the rat, these results suggest a similar role for the kidney in man. No evidence has been found linking free A-1 with hypertriglyceridaemia in patients with renal failure as has been suggested previously.

Stability of free apolipoprotein A-1 concentration in serum, and its measurement in normal and hyperlipidemic subjects.

Free apolipoprotein A-1 (free A-1) is a low-molecular-mass complex of protein and lipid containing apolipoprotein A-1 (apo A-1). Using crossed immunoelectrophoresis, we separated free A-1 from the apo A-1 in high-density lipoproteins (HDL) and quantified free A-1 by comparison with a reference serum (containing 1.45 g of apo A-1 per liter) diluted in 9 mol/L urea solution. This latter treatment yields apo A-1 containing protein-lipid complexes of the same size and electrophoretic mobility as free A-1. Within-day precision (CV), determined by replicate analysis of two samples with mean free A-1 concentrations of 48 and 138 mg/L, was 9.1 and 7.2%, respectively. We also showed that the concentration of free A-1 is not stable in serum or plasma either at 4 degrees C or when frozen. The mean concentration of free A-1 in 28 fasted, healthy subjects was 75.3 (SD 13.6) mg/L. The postprandial increase was not statistically significant. The percentage of total apo A-1 in the free form in serum ranged from 3.5% to 8.1%, less than the 10% to 30% reported by others who used radial immunodiffusion to measure free A-1. Because radial immunodiffusion does not separate free A-1 from HDL, we believe that that technique overestimates free A-1. We also used crossed immunoelectrophoresis to measure free A-1 in 76 hyperlipidemic patients. Those with Fredrickson types III and V had significantly increased concentrations of free A-1 (P less than .0001). Correlations between free A-1 and cholesterol and triglycerides in serum were significant (P less than .005 and P less than .001, respectively). Possible roles for free A-1 in lipid metabolism are discussed.

Non-secretory multiple myeloma: a report of 13 cases with a review of the literature.

The clinical features of 13 patients with non-secretory myeloma from a series of 172 consecutive multiple myelomas are presented. The non-secretors survived significantly longer that the secretors, median 46 months versus 21 months (p less than 0.01). Non-secretory myeloma was associated with a higher incidence of neurological presentation, minimal lytic bone disease, a lower median percentage of plasma cells in the marrow and a lower incidence of hypogammaglobulinaemia. The median survival of the non-secretors with minimal lytic bone lesions was 74 months compared to 21 months for those with extensive bone disease. The superior survival of non-secretors is thus thought to be due to earlier presentation possibly as a result of a tendency to form symptomatic local tumours. Retrospective immunoperoxidase staining of stored tissue was performed in nine cases. In only one of these was a monoclonal immunoglobulin not detected indicating that true 'non-production' is rare. In four patients who produced a biochemically detectable paraprotein during the course of their disease and in whom immunoperoxidase data was available the immunoglobulin was of the same type. Immunoperoxidase staining may help in the initial diagnosis of non-secretory myeloma but did not contribute any prognostic information.

A method for the identification of apolipoprotein E isoforms employing chemical precipitation and flat bed isoelectric focusing in agarose.

A method is described for the identification of apolipoprotein E phenotypes. Lipoproteins were precipitated by magnesium chloride/phosphotungstate reagent and isoelectric focusing performed on flat-bed agarose. Sensitivity was enhanced by blotting with nitrocellulose prior to staining. The system described requires no ultracentrifugation step and allows up to 20 samples to be processed in each run. Agarose has some advantages over the more commonly used polyacrylamide gels for isoelectric focusing.

Limitations of immune complex measurements in colorectal disease.

Three techniques (Clq, Raji and L1210 binding assays) alleged to measure circulating immune complexes (ICs) were applied to the sera of 101 patients with colorectal disease (54 carcinoma; 23 inflammatory; 13 benign tumour and 11 miscellaneous) at the time of diagnostic or definitive surgery, and 58 healthy adult controls. Elevated levels in the pathological sera were observed by all 3 methods in order of sensitivity: Raji greater than Clq greater than L1210. However, none of them differentiated between benign, inflammatory and neoplastic conditions nor, in the case of colorectal carcinoma, was there any correlation with stage of disease. With the exception of Raji v. L1210 (r = 0.43, P less than 0.001), correlations between the various assays were poor and levels of serum carcinoembryonic antigen (CEA) did not correlate with ICs measured by any of the techniques. Indeed, the IC assays were even less discriminatory than CEA, which was elevated mainly in the serum of carcinoma patients and which was positively correlated with serum gamma-glutamyl transpeptidase (gamma GT) (r = 0.42, P less than 0.005). The data suggest that the lack of concordance between the IC assays is a reflection of heterogeneity among ICs, interfering factors present in pathological sera, or both. Thus the IC assays deployed here have neither diagnostic nor prognostic utility in colorectal disease at this time, and immunochemical characterization of the serum reactive material detected by the different assays is required.

Abnormal liver function during nutritional support in postoperative cancer patients.

Patients who receive total intravenous or nasogastric nutritional support after surgery for head and neck cancer show abnormalities of liver function. Twenty such patients were maintained in positive nitrogen balance. Serum alkaline phosphatase and aspartate aminotransferase values were increased in 15 and 18 cases respectively. Possible causes for the abnormalities are discussed and further investigations proposed.

Postoperative hypophosphataemia.

The possible mechanisms of postoperative hypophosphataemia were studied in women undergoing uncomplicated cholecystectomy. Six patients were allocated to each of three groups. Group I received no intravenous fluids, group II received dextrose/saline solution alone and group III received dextrose/saline solution with phosphorus supplementation. The serum concentration of inorganic phosphorus fell in all three groups, the greatest fall being in the group receiving dextrose/saline solution. However, the lowest level reached (0.82 mmol/l) was within the normal range for our laboratory. Concentrations of red blood cell adenosine triphosphate and 2,3-diphosphoglycerate showed similar changes. The operations were not associated with a large catabolic response nor with an increase in urinary phosphorus excretion. The postoperative reduction in serum concentration of inorganic phosphorus appeared to be due mainly to haemodilution. There is no indication for routine phosphorus supplementation following uncomplicated elective surgery.

An investigation into the immunochemical properties of the isoenzymes of human alkaline phosphatase.

A study was carried out to investigate the immunochemical properties of the alkaline phosphatases present in liver, placenta, intestine, and kidney. Butanol extracts of the tissues were examined by antigen-antibody crossed electrophoresis, and the immunoprecipitates formed by the enzymes were identified by use of a specific stain for alkaline phosphatase. The results obtained revealed three immuno-chemical types of alkaline phosphatase, designated L, P, and PI respectively. The distribution of these enzymes among the tissues examined was as follows: type L was the only enzyme detected in liver extract and type P the only one detected in placental extract. The extracts of intestine and kidney both contained two isoenzymes, one of which was type L and the other type PI.

A comparison of fat absorption in young and old subjects.

Using an oral fat load, it is demonstrated that the pattern of absorption in elderly subjects is significantly different from that found in younger controls. This change may be due to the slower gastric emptying or reduced pancreatic function observed in this study. The possibility of impaired small bowel absorption has not been excluded.

Value of routine serum-triiodothyronine estimation in diagnosis of thyrotoxicosis.

Thyroid-stimulating hormone (T.S.H.), triiodothyronine (T3), and thyroxine (T4) concentrations were estimated on 432 blood specimens from patients with a provisional diagnosis of thyrotoxicosis. 59 patients had a raised serum T3 concentration with T.S.H. and T4 levels in the normal range. Further information was obtained in 41 of these patients, and T3 toxicosis was diagnosed in 17 cases, thus providing a projected total of 24 patients with T3 toxicosis. In addition, there were 56 patients, with more common biochemical features of thyrotoxicosis, having both a raised serum T3 and T4 concentration. Therefore 30% of the patients considered thyrotoxic in this retrospective survey were only diagnosed with the aid of a serum-T3 estimation.

Agglutination of platelets by a serum factor in the presence of EDTA.

The platelets of a patient with reticulum-cell sarcoma were found to exhibit agglutination and cytopathic changes when her blood was treated with EDTA but not with other anticoagulants. Investigation showed that the phenomenon was caused by a serum factor that was probably an antibody.