Renal excretion of uric acid in the rat: a micropuncture and microperfusion study.

Free-flow micropuncture experiments were done in rats of three strains infused with small amounts of urate [plasma urate (P urate) = 95 +/- 8 muM]. Urate concentrations in tubular fluid were measured by an accurate chemical fluorometric ultramicromethod. In fluid from surface glomeruli, the glomerular fluid-to-plasma urate ratio [GF/P) urate] was 0.99 +/- 0.03 (n=11), i.e., lower than expected for total ultrafiltrability of plasma urate. Along proximal convolutions, net reabsorption of 55% of filtered urate was demonstrated. Small amounts of urate may have been reabsorbed between late proximal and early distal sites. Net transepithelial movements of urate did not occur in distal tubules or collecting ducts. In microperfusion experiments on proximal tubules, both a reabsorptive flow of urate (loss of perfused [2-14C]urate) and a secretory flow (entrance of cold urate into perfusate) of the same order of magnitude were demonstrated. Neither flow was influenced by simultaneous water movements. Microperfusion of Henle's loops indicated a significant but very small net reabsorption.     

"Affinity maturation" of ligands for HCV-specific serum antibodies

We have previously screened a phage-displayed random peptide library using sera from patients and identified ligands binding to antibodies specifically associated with the hepatitis C virus infection. The ability of these peptides to detect HCV-specific antibodies was improved through an in vitro procedure which mimics the natural process of antibody affinity maturation operating in secondary immune response. Libraries were generated by mutating the sequence of the original peptide through a protocol that efficiently introduced substitution, insertion and deletion mutations on a single or population of clones. Screening these libraries isolated mutants that displayed increased specific reactivity with a broader range of sera from HCV-infected patients. Several variants of the original peptide were identified which discriminate between the various components of the specific polyclonal response. This methodology to select artificial ligands from RPL using sera and to enhance their diagnostic properties by affinity maturation makes the development of a diagnostic assay to detect disease-associated antibodies feasible, without requiring the natural antigen.     

Increased HLA-DR homozygosity associated with pre-eclampsia

It is generally accepted that maternal recognition of paternally derived fetal antigens occurs during normal pregnancy and may be beneficial for implantation and maintenance of gestation. Thus, we have investigated the human leukocyte class II DR antigens (HLA-DR), whose role in self and non-self recognition is well known, in women with pre-eclampsia, their partners and in control couples. The HLA-DR antigens were tested in 70 pre-eclamptic primigravidae women and their partners and 70 healthy control couples using the serological Terasaki technique. Our results did not show any particular HLA-DR antigen to be correlated with pre-eclampsia, but a statistically significant increase of only one identifiable HLA-DR antigen, which was presumed to express homozygosity at the HLA-DR locus, in the pre-eclamptic women and their partners: 67.1 versus 7. 9% in the control couples (P < 0.000001). The analysis of HLA-DR compatibility between pre-eclamptic women and their partners showed a statistically highly significant increase of the female-to-male compatibility (P = 0.0003) and a lower but significant male-to-female compatibility in comparison with controls (P = 0.014). From our results, it emerges that HLA-DR homozygosity and reduced antigenic disparity seem to be associated to a major risk for pre-eclampsia, which consequently appears to be a 'couple's disease'.     

Multiple islet cell tumors with predominance of glucagon-producing cells and ulcer disease

Two cases of multiple islet cell tumors mostly composed of glucagon-producing cells and associated with severe ulcer disease are presented. Multiple endocrine neoplasia type I (MEN-I) was present in both patients, although symptomatically latent in case 2. Immunohistochemistry showed that glucagon (A) cells were a major cell population (i.e., accounting for at least 30% of the tumor cell population) in 24 of 43 tumors (either macroadenomas or microadenomas) studied in case 1 and in 12 of 17 tumors studied in case 2. A major pancreatic polypeptide (PP) cell population was found in 12 and 7 tumors of case 1 and 2, respectively. In contrast, insulin (B) and somatostatin (D) cells were scarce in most adenomas. Gastrin-producing cells were not identified in any tumors, despite the use of different antigastrin antisera. Extrapancreatic or residual gastrinomas were not found at postmortem examination in case 1 or on appropriate surgical inspection done 24 years after the onset of the ulcer disease in patient 2. On the basis of these and of 17 additional cases collected in the literature, it is concluded that multiple A-cell tumors of the pancreas are an expression of the MEN-I and are mostly associated with ulcer disease and/or with hypergastrinemia of frequent uncertain origin. The mechanisms regulating the nonrandom phenotypic hormonal differentiation of these genetically determined tumors remain unknown.     

Skeletal muscle and cardiac changes with training in patients with angina pectoris

Cardiovascular and skeletal muscle adaptations were studied before and after 6 mo of physical training in patients with coronary artery disease and exertional angina pectoris. Symptom-limited exercise capacity increased by 41% (470 +/- 30 to 665 +/- 35 kg.m.min-1; n = 29, P less than 0.001) with training as did skeletal muscle succinate dehydrogenase activity (1.75 +/- 0.24 to 3.31 +/- 0.24 IU; n = 23, P less than 0.001) and the areas of muscle fibers (type I from 43.6 +/- 3.3 to 54.4 +/- 3.3 micrometers 2 X 10(2); n = 21, P less than 0.05 and type II from 43.9 +/- 2.4 to 57.2 +/- 5.1 micrometers 2 X 10(2); P less than 0.01). At the same submaximal exercise intensity (mean 355 +/- 100 km.m.min-1), plasma catecholamines (1.31 +/- 0.14 to 1.07 +/- 0.09 ng.ml-1; n = 13, P less than 0.05), heart rate (115 +/- 3 to 97 +/- 3 beats/min; n = 29, P less than 0.001), and systolic blood pressure (171 +/- 4 to 143 +2- 4 mmHg; n = 29, P less than 0.001) were significantly reduced after training. Maximal coronary sinus blood flow (192 +/- 10 to 208 +/- 9 ml.min-1; n = 29, P less than 0.05) and left ventricular oxygen consumption (23.2 +/- 1.5 to 25.8 +/- 1.6 ml.min-1; n = 24, P less than 0.05) were increased by 8 and 11%, respectively, after training. The improvement in exercise capacity with training in patients with exercise is secondary to a reduction in myocardial oxygen requirements during subangina levels of exercise and partly to a small increase in maximal myocardial oxygen consumption. The skeletal muscle adaptations with training were not related to other indices of training such as the reduced exercise heart rate or increased symptom-limited exercise capacity.     

Expression of HLA-DR and common acute lymphoblastic leukemia antigens on glioma cells

The expression on several established human glioma cell lines of two well-defined differentiation antigens, HLA-DR and the common acute lymphoblastic leukemia antigen (CALLA) has been demonstrated. Rabbit anti-CALLA antiserum and monoclonal anti-la antibodies specifically lysed glioma cells in the presence of complement. Absorption of anti-CALLA antiserum and anti-Ia antibodies by glioma cells abolished their cytotoxicity against blasts isolated from a common acute lymphoblastic leukemia. Immunoprecipitation of solubilized glioma cells by monoclonal anti-Ia antibodies revealed two polypeptide chains of 28 and 33 kDa, whereas the anti-CALLA antiserum precipitated a single polypeptide chain of 100 kDa.     

Anti-HIV-1 activity of antiviral compounds, as quantitated by a focal immunoassay in CD4+ HeLa cells and a plaque assay in MT-4 cells

The inhibitory effects of a series of antiviral compounds on human immunodeficiency virus type 1 (HIV-1) were evaluated in a plaque assay (PA) in MT-4 cells and a focal immunoassay (FIA) in CD4+ HeLa cells. Similar 50% inhibitory concentrations (IC50) were obtained for the sulfated polysaccharides when measured by PA or FIA: the IC50 values of dextran sulfate and pentosan polysulfate were 0.8 microgram/ml and 0.35 microgram/ml, respectively. Also, comparable IC50 values (ranging from 1.42 to 2.71 microM) were obtained for purine 2',3'-dideoxyribosides (i.e. DDA, DDI and DDG) when evaluated by PA or FIA. In contrast, the IC50 values of pyrimidine 2',3'-dideoxyribosides were invariably 4- to 10-fold lower when monitored by PA than FIA: the IC50s of AZT, D4T and DDC in the PA were 0.015, 0.094 and 0.038 microM, respectively, and in the FIA were 0.062 microM, 0.29 microM and 0.46 microM, respectively. The differential anti-HIV-1 activities found with AZT, D4T and DDC in the PA and FIA systems may at least be related in part to differences in the metabolism of the compounds (i.e. phosphorylation by thymidine kinase or 2'-deoxycytidine kinase) between MT-4 and CD4+ HeLa cells. The novel anti-HIV-1 compounds tetrahydro-imidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-thione (TIBO) derivatives, R82150 and R82913, and the acyclouridine derivative 1-[(2-hydroxyethoxy)methyl]-6-phenylthiothymine (HEPT) were also more inhibitory to HIV-1 in the PA than FIA system. The IC50 values of R82150, R82913 and HEPT, as based on PA, were 0.005, 0.003 and 0.79 microM, respectively. Their IC50 values, as based on FIA, were 0.020 microM, 0.015 microM and 3.77 microM, respectively. The TIBO derivatives emerged as the most effective HIV-1 inhibitors of the compounds tested whether assayed by PA or FIA.     

Social status and nerve growth factor serum levels after agonistic encounters in mice

Ten repeated daily interactions (20 min each) of the same pairs of isolated male mice produced a clear distinction between attacking (dominant) and defeated (subordinate) animals. The fighting level remained fairly constant over the 10 days. One hr after the end of the 10th session, the increase in serum NGF levels described previously (2) was significantly more marked in subordinate than in dominant mice. The mean level of serum NGF was correlated with the number of fighting episodes, particularly in the case of dominant individuals. Moreover, within-pair differences in NGF values were correlated with differences in locomotor activity between dominants and subordinates; this makes it possible that stimuli other than those produced by fighting per se may be responsible for the increase in circulating NGF. As is well known, the adrenal hypertrophy produced by fighting stress is more marked in subordinate than in dominant mice, while previous work has shown that stress of a nonpsychosocial kind does not elevate serum NGF levels. Therefore, the present data support the hypothesis that NGF release contributes to the modulation of adrenal function in a situation-specific fashion.     

Peripheral blood mononuclear cell populations in men with "idiopathic" infertility with antisperm autoantibodies

Peripheral blood mononuclear cell populations in ten men, with idiopathic infertility with serum sperm agglutinating antibodies at a titre of 1/32, were evaluated. Mononuclear cells were enumerated using the monoclonal antibodies OKT3 (pan T cells), OKT4 (helper/inducer T cells), OKT8 (suppressor/cytotoxic T cells), Leu 7 (monocytes, null cells, and natural killer (NK) cells), OKIa (B cells, monocytes, null cells and activated T cells). Blood mononuclear cells with surface receptors for complement (B lymphocytes and a proportion of monocytes and null cells) were enumerated using a rosette test (EAC). The following abnormalities, compared to normal subjects, of blood mononuclear cell population were found: a decreased percentage of OKT3 (+) cells (p less than 0.01), a decreased percentage of OKT8 + cells (p less than 0.001) and increased OKT4/OKT8 ratio (p less than 0.001), an increased percentage of OKIAI cells (p less than 0.001). Levels of OKT4+ and Leu 7 cells and the percentage of EAC rosette forming cells were not significantly different from those in normal subjects. Regression analysis showed a significant correlation between the percentage of OKIAI cells and sperm agglutinating antibodies. After all that, significant correlation between humoral and cell-mediated immunity in patients with idiopathic infertility with antisperm autoantibodies, were observed.