The effects of monocyte-conditioned medium and interleukin 1 on the synthesis of collagenous and non-collagenous proteins by mouse bone and human bone cells in vitro

Cultural adherent human mononuclear cells produce factor(s) which stimulate the release of calcium from new-born mouse calvaria in organ culture. This stimulation of bone resorption is accompanied by an inhibition of the incorporation of [³H]proline into collagen which is independent of increased prostaglandin production by the bone. When human osteoblast-like cells are treated with conditioned medium from human mononuclear cells, collagen accounts for a decreased proportion of the protein synthesised. This effect on matrix synthesis is not accompanied by an inhibitory action of the monocyte-conditioned medium preparations on net cell proliferation. In human osteoblast-like cell cultures, partially purified human interleukin 1 also inhibits the production of the bone-specific protein osteocalcin in a dose-dependent fashion. These observations are consistent with the hypothesis that products of human monocytes similar to, or identical with, human interleukin 1 may be important regulators of bone metabolism and may contribute to the bone loss seen in diseases such as chronic rheumatoid arthritis.     

Class I-like MHC molecules expressed by baboon placental syncytiotrophoblast

Human placental villous trophoblast is known to be unreactive with W6/32 and other monoclonal antibodies recognizing monomorphic determinants of human class I MHC heavy chains, whereas extravillous cytotrophoblast in the placental bed is W6/32-reactive by immunohistology. We have now demonstrated, in contrast, that syncytiotrophoblast is the only cellular component of baboon early placental villous tissue which is reactive with any of these antibodies. Radioimmunoprecipitation of detergent-solubilized baboon placental membrane preparations, and subsequent SDS-PAGE, has shown the W6/32-reactive component to have an m.w. of 41,000 and to be associated with beta 2-microglobulin, whereas baboon peripheral lymphocytes express 45,000 m.w. W6/32-reactive antigens comparable with the HLA-A,B,C heavy chains of human lymphocytes.     

Degranulation of eosinophilic granule cells induced by capsaicin and substance P in the intestine of the rainbow trout (Oncorhynchus mykiss Walbaum)

Summary Adult rainbow trout (Oncorhynchus mykiss) were injected intraperitoneally with capsaicin, substance P, serotonin, or a control of saline vehicle or bovine serum albumin (0.5 g/g body weight). Fish were sacrificed 30 min and 1,2 and 4 h post-injection, the gut was dissected out, and a small section of the upper intestine was processed for electron microscopy. A significant proportion of eosinophilic granule cells (EGCs) of the intestine were in close association with non-myelinated neuronal bundles in all fish (4 fish per treatment and time period), but there was no significant difference between treatment or time, suggesting that the association was unaffected by these factors. Close examination of EGC ultrastructure showed that fish treated with capsaicin and substance P exhibited limited degranulation of the EGCs in the stratum compactum and extensive crinophagic-like degranulation in the lamina propria. Cells of the lamina propria contained characteristic multivesicular-like bodies. The degranulation was reminiscent of both mast cell degranulation and endocrine cell crinophagy. EGCs of fish treated with serotonin or a control were unaffected, suggesting that the serotoninergic neurons, believed to be involved in gut motility, were not responsible for degranulation. It is apparent that EGCs of the trout intestine may be under nervous control, as has been demonstrated previously for mammalian mast cells.     

Antithrombin Glasgow, 393 Arg to His: a P1 reactive site variant with increased heparin affinity but no thrombin inhibitory activity

Antithrombin Glasgow is a hereditary abnormal antithrombin that has lost thrombin inhibitory activity. It was isolated from the plasma of a 41-year-old male with a history of thrombotic events. Antithrombin Glasgow was purified from plasma using heparin-Sepharose chromatography at pH 7.4 eluting with increasing concentrations of NaCl. The normal protein eluted with 0.9 mol/l NaCl and Glasgow with 1.05 mol/l NaCl. Electrophoresis in agarose at pH 8.6 showed the variant to migrate more anodally than normal. The C-terminal small fragment resulting from catalytic cleavage with elastase between P3 and P4 of the reactive loop was isolated and sequenced. This showed the replacement of the arginine at residue 3 by a histidine. This is residue 393 in the intact molecule. The findings suggest that heparin, on binding, interacts indirectly with the reactive centre region of antithrombin.     

Rapid Increase of Pneumococcal Resistance to β-Lactam and Other Antibiotics in Isolates from the Respiratory Tract (Nagasaki,Japan: 1975–1994)

The susceptibility of 101 pneumococcal isolates from the respiratory tract during 1991–1994 was examined and compared with the susceptibility of isolates over the period of 1975–1990. A rapid increase of resistance was seen not only to penicillin but also other antimicrobial agents. During 1991–1994, 38% of all the isolates were resistant to penicillin. The rates of resistance during this period were 16–23% for three newer cephalosporins, 18% for imipenem, 69% for tetracycline, 31% for erythromycin, 20% for chloramphenicol and 9% for clindamycin. The use of antibiotics within one month prior to pneumococcal isolation was correlated with penicillin resistance (P < 0.05). Serotyping of the isolates by antiserum revealed differences in predominant types between penicillin-resistant (19F, 23F, 4) and -susceptible isolates (15, 4, 11A). Our data suggests that anti-pneumococcal antibiotics should be carefully chosen on the basis of susceptibility tests.     

Use of the true absorption coefficient as a measure of bioavailability of radiocaesium in ruminants

Limitations of existing methods to describe the bioavailability of dietary radionuclides to ruminants (the transfer coefficient and apparent absorption coefficient) have led to the alternative suggestion of using the true absorption coefficient (A _t). Various approaches to estimatingA _t for radiocaesium, involving the intravenous administration of a second isotope, are presented and discussed with reference to results from studies in which a range of radiocaesium sources were examined in sheep. Although estimates ofA _t differed between the sources, they were reasonably consistent between measurement techniques. Those methods which involved the estimation of endogenous faecal excretion of radiocaesium could be used with previously contaminated animals and did not require continuous administrations of radiocaesium isotopes, but gave unreliable results for sources of low bioavailability. Methods based on estimating the turnover rate of dietary radiocaesium through blood plasma were sufficiently sensitive to measureA _t for the range of sources studied. However, they require previously uncontaminated animals and continuous administration of both isotopes for approximately 7 days. Bioavailability is more effectively measured asA _t than as the transfer or apparent absorption coefficients sinceA _t does not incorporate factors relating to the metabolism of radiocaesium in the tissues of the animal. The results of these studies show that differences in transfer coefficients between sheep and cattle and between sheep of differing ages are not due to variation in absorption across the gut. The potential for applying these approaches to other radioactive elements is discussed.     

Restriction endonuclease mapping of the colicin Ib plasmid

Summary A cleavage site map of the colicin Ib plasmid (ColIb) has been determined for the enzymes Sall, XhoI, and HindIII by analysis of partial digests, double digests, DNA-DNA hybridization, and Tn5-induced insertion mutants. The site of the colicin gene has been determined by probing with cloned DNA coding for colicin production, as well as by analysis of a colicin negative ColIb:Tn5.     

A Comparative Study of Avidin-Biotin-Peroxidase Complexes for the Immunohistochemical Detection of Antigens in Neural Tissue

It has been suggested that the use of avidin-biotin immunohistochemical techniques for antigen detection in neural tissue produces nonspecific background staining. For this reason neural tissue was used to test the quality, sensitivity and specificity of four commercially available antibody detection kits which use avidin or streptavidin binding to biotin. Free-floating, thick-section immunohistochemistry on perfusion fixed rat central nervous system revealed variability among staining kits for all parameters analyzed under the same experimental conditions. The reagents from the Vector 'Elite' kit were the most sensitive and specific, and received the highest overall rating for quality. Most commercial products tested could be used at greater dilutions than those recommended by the manufacturers without compromising specific staining. No staining was evident when the primary and secondary antibodies were omitted. This suggests that nonspecific binding is unlikely to be due to endogenous ligands, charge of hydrophilic reactions between these tertiary complexes and the tissue sections.     

Insulin-secreting beta-cells possess specific receptors for interleukin-1 beta

The effect of the cytokine interleukin-1 beta on the insulin secretory responsiveness of single beta-cells (HIT-T15) was investigated. In the short-term, IL-1 beta induced a dosage-dependent stimulation of insulin release. In contrast, in the long-term, IL-1 beta, inhibited both basal and secretagogue-stimulated insulin secretion. We also demonstrate the simultaneous presence of specific high and low affinity binding sites for IL-1 beta on beta-cells. IL-1 beta, which has been implicated in the pathogenesis of insulin-dependent diabetes, may therefore mediate its opposing effects on beta-cells through a specific plasma membrane receptor.