Liver-specific and shared cell membrane antigens. Studies by light- and electron microscopy.

Liver-specific and shared saline-insoluble cell surface antigens were localized by immunofluorescence as well as by light- and electron microscopic immunoenzyme techniques. Antisera against purified mouse liver cell membranes were surface membrane but not organ-specific. Variable quantities of shared antigens were present in endoderm- and mesoderm-derived organs but not in ectodermal nerve tissue. Species crossreactivity was observed for the rat. Repeated absorption produced liver-specific antisera that reacted with antigenic sites distributed along the entire hepatocyte and sinusoidal cell surfaces. For the precise localization as well as the detection of low concentrations of both liver-specific and nonspecific antigens, the ultrastructural visualization of reactive sites proved essential.     

Insoluble polyanions as activators of both pathways of complement

Soluble polyanions, e.g. dextran sulphate, are known to interact with components of the classical pathway of complement and also to activate the alternative pathway (APC).† Insoluble polyanions offer the opportunity to isolate and to characterize intermediates of the reaction sequence. Sephadex, an insoluble, crosslinked dextran, was substituted with sulphate groups using chlorosulphonic acid. The sulphated Sephadex (SS) activated the APC in normal and in C4-deficient-guinea-pig serum as shown by haemolytic and immunochemical methods. After incubation of SS with normal guinea-pig serum, a C3-cleaving enzyme bound to the SS particles was present. This enzyme was inhibited by antisera against the components C2 and C4. Anti-serum against factor B or anti-C3-Fab had no inhibitory effect. Incubation at 37° inactivated the enzyme; activity was restored by incubation with C2, but not with factors B and D of the APC. These results suggest the presence of the C[unk]42-enzyme bound to the SS particles after incubation with normal serum. However, preincubation of SS with C4 deficient serum did not yield an enzyme which could act on purified C3, but enzymatic activity cleaving C4 and C2 was present, indicating that binding and activation of C1 had occurred. Utilizing purified C[unk]1, it was shown that SS binds purified C[unk]1 in a functionally active state. These data indicate that the polyanion SS has a dual function: SS activates both the APC and the classical sequence. Thus, the chemically simple, ester-linked, anionic sulphate groups, distributed along crosslinked polysaccharide chains, are sufficient to be recognized as initiating signal for both pathways of complement.     

Hydatidiform mole: parental chromosome aberrations in partial and complete moles.

The relationship between parental constitutional chromosome abnormalities and the development of hydatidiform mole was evaluated in series from four institutions. Karyotype analysis was performed on blood samples from 237 patients with a pathological diagnosis of complete mole and 217 of their spouses. One patient was found to have a constitutional balanced translocation, t(11;18), while one spouse was found to have a balanced translocation, t(4;20). Among 125 patients with partial mole and 106 of their spouses, one male was found to be a translocation carrier, t(13;14). No significant increase in the frequency of translocations in the parents of complete moles was found in any of the series considered separately or together. Data from the combined series show no evidence of constitutional parental chromosome aberrations as an aetiological factor in the development of molar pregnancies.     

Cyclosporin A Inhibits a Discrete Step in T-Lymphocyte Stimulation

Cyclosporin A (CyA) interferes with immune responses and prevents growth factor release by stimulated T cells. However, it is not known whether this is due to an effect on the accessory cells, required for T-cell responses, whether antigen recognition cannot occur, or whether later steps, leading to lymphokine production, are blocked. For this reason, the effect of CyA on homogeneous populations of T tumour cells was investigated. The immunosuppressive compound efficiently prevented T-cell growth factor (TCGF) (interleukin 2) release by stimulated tumour cells. Still, the cells retained the surface antigen T3, known to be involved in T-cell stimulation, after treatment with CyA. Furthermore, CyA failed to affect the inhibition of proliferation, observed in a T-cell tumour in response to stimulation, indicating that the cells had received the stimulatory impetus, TCGF release, induced by treatment with a phorbol ester, was only partly sensitive to inhibition by CyA, demonstrating that CyA will interfere with discrete aspects of the stimulation of a T-cell.     

Effect of spleen exposure to ultrasound on cellular and antibody-mediated immune reactions in man

Spleen exposure to ultrasound has been reported to influence antibody response to sheep red blood cell injection in mice (decreased hemagglutination and hemolytic titers and IgM, IgG2a and IgG2b levels and elevated IgG1 levels). In a controlled clinical trial, we investigated the possible immunosuppressive side-effect of splenic exposure (2.0 mW/m², 3.5 MHz, 5 minutes) to ultrasound on the immune response to Rubella vaccination in 41 anti-Rubella antibody-negative volunteers. The measured parameters (blood cell count, IgA, IgM, IgG including subclasses IgG1-IgG4, isoagglutinins, anti-Rubella hemagglutinin and hemolysin titers, complement C3, skin tests to mumps and tuberculin, T, B and O lymphocytes, esterase-positive and negative T-cell subsets) suggest changes dependent on the time of vaccination, but provide no evidence of an immunosuppressive effect of ultrasound in man.     

Two kinds of resting discharge in cat muscle spindles.

1. The behavior of primary endings of cat soleus muscle spindles was studied during shortening steps carried out at different muscle lengths. 2. Spindles were of two kinds: one, silent spindles, whose afferents fell silent after the shortening, at least over part of the range of lengths tested. The second, spontaneous spindles, resumed firing at all lengths. 3. For silent spindles, the duration of the silent period, measured at lengths where they did recover a resting rate, depended directly on muscle length and became shorter at longer lengths. This is what would be expected if the slack introduced in the spindle by the shortening step was removed more rapidly at longer lengths by the higher passive tension. For spontaneous spindles, on the other hand, the duration of the silent period after the shortening was largely independent of muscle length and depended on the spindle's rate of firing immediately before the shortening. 4. At intermediate lengths the discharge of slack spontaneous spindles remained unaffected by an isometric muscle contraction. It was therefore not possible to produce a pause in the discharge, behavior normally taken as typical of spindles. The discharge could be interrupted by the contraction if this was combined with a large shortening movement. 5. It is proposed that when intrafusal fibers are slackened by a shortening step, the resting discharge in spontaneous spindles is generated by a maintained depolarization of the annulospiral ending resulting from extension of the terminal coils by forces from within the receptor. A shortening contraction compresses the spirals to interrupt the discharge. The sensory endings of silent spindles remain below threshold until the spirals have been opened out sufficiently by external stretch.     

Calcium dependence of histamine-induced increases in capillary permeability in isolated perfused rat hindquarters

Experiments were performed on isolated maximally vasodilated perfused rat hindquarters to evaluate the role of calcium and magnesium for the capillary permeability increase(s) elicited by histamine. Changes in capillary permeability were quantified by determinations of capillary filtration coefficient (CFC) with gravimetric technique, and capillary diffusion capacity (PS) for vitamin B12 (MW = 1,355) with a single injection indicator dilution technique. During control, vascular resistance was 2.2 PRU100 at a flow of 9.4 ml min-1 per 100 g, and PS for B12 was 3.7 +/- 0.1 ml min-1 per 100 g, while CFC was 0.0377 +/- 0.0004 ml min-1 mmHg-1 per 100 g. Perfusion with 'Mg-free' solution for 1 h caused a 24% increase in CFC, while neither 'Ca-free' perfusion nor perfusion with verapamil (5 X 10(-5) M) nor felodipine (1 X 10(-6) M) induced any changes in CFC. Histamine (100-200 microM) caused in all preparations a 150-200% increase in CFC with only small changes in PS for B12. This histamine effect was absent after 1 h of 'Ca-free' perfusion and was partially blocked after 1 h of perfusion with 0.1 mM calcium, while the calcium antagonists verapamil and felodipine had no effects on the histamine-induced changes. The results imply that histamine exerts its action on the endothelial cells through a calcium-dependent process, probably involving low affinity calcium sites but this process could not be inhibited by the calcium antagonists used. Thus, endothelial cell contractility, which probably is responsible for the histamine-induced increase in capillary permeability, exhibits unique characteristics, differing from those of vascular smooth muscle.     

Disposition of oxazepam in patients on maintenance hemodialysis

Summary The pharmacokinetics of a single 30-mg oral dose of oxazepam was evaluated in seven patients with chronic renal failure on maintenance hemodialysis and in seven healthy controls matched for age and sex. Based on total (free plus bound) serum oxazepam concentrations, elimination half-life was prolonged in renal patients compared to controls (22 vs 8 h,p<0.001) and volume of distribution increased (3.0 vs 1.4 1/kg,p<0.02). However, total clearance was similar between groups (1.8 vs 1.9 ml/min per kilogram). These findings were confounded by the increased oxazepam free fraction in serum of renal failure patients (10.3%) as compared to healthy controls (4.3%). Correction for differences in binding indicates similar distribution of unbound oxazepam between groups, but reduced clearance of pharmacologically active unbound oxazepam in renal patients (18 vs 45 ml/min per kilogram). Oxazepam dosage, therefore, may require downward adjustment for renal failure patients on hemodialysis.Supported in part by grant OC 10/6-3 from the Deutsche Forschungsgemeinschaft, and by grant MH-34223 from the United States Public Health Service