Platelet-activating factor in late asthmatic response

The role of platelet-activating factor (PAF) in the late asthmatic responses was studied. The concentrations of lyso-form of PAF in plasma were measured at 0 and 20 min, and 6 and 24 h after the antigen inhalation challenge among patients with bronchial asthma. PAF activities were measured by their aggregating ability of washed rabbit platelets after acetylation of lyso-PAF into the biological active form of PAF, when there were no detectable amounts of PAF in plasma. The concentrations of lyso-PAF were found to be significantly increased in patients with the late asthmatic response compared with patients with the single immediate response at 6 h after the antigen challenge. In contrast, lyso-PAF levels were not significantly different at 20 min after the antigen challenge between these two groups. PAF inactivator activity in plasma increased when there was a decrease in the lyso-PAF level. These results suggest that PAF may participate in the late asthmatic response and may provide a new insight into the pathogenesis and the treatment of bronchial asthma.     

A novel missense mutation in human lactate dehydrogenase B-subunit gene

Reduced activity of serum lactate dehydrogenase (LDH; EC 1.1.1.27) was found in a male medical student during practical examinations of his own blood. Serum LDH isoenzyme pattern showed reductions in activities of the isoenzymes with lower subunit A/B ratios such as LDH1 and LDH2. These findings were indicative of a partial LDH-B subunit deficiency, which was confirmed in erythrocyte hemolysates by Western blotting. Polymerase chain reaction (PCR)-based DNA sequence analysis of the LDH-B subunit gene revealed a heterozygous nucleotide change: a guanine to adenine substitution in codon 69 (GGG --> GAG) at the third exon of the LDH-B subunit gene that resulted in a glycine to glutamic acid substitution (G69E). The mutation was confirmed by PCR-restriction fragment length polymorphism (RFLP) analysis using a mismatched primer to introduce a new NcoI restriction site. The same heterozygous mutation was found in his mother but not in other family members. This mutation involves a residue belonging to alphaC helix in LDH-B subunit protein molecule that functions as an interface for other subunits.     

Calcium-dependent slow outward current in visceral primary afferent neurones of the rabbit

Slow outward currents were recorded from voltage-clamped neurones in nodose ganglia excised from rabbits. In the majority of Type C neurones, a short depolarizing command pulse evoked a slow outward tail current (I _SAH) with a decay time constant ranging from 0.5 to 2 s. TheI _SAH was due to an increase in membrane conductance to K⁺ because its reversal potential was approximately equal to the Nernst potential for K⁺. TheI _SAH was reversibly blocked by removal of external Ca²⁺ or by Ca²⁺ antagonists. A Ca²⁺ ionophore, A23187, produced an outward current which was similar to theI _SAH. TheI _SAH was resistant to tetraethylammonium and depressed by Ba²⁺, whereas it was not affected by Cs⁺ and 4-aminopyridine. TheI _SAH was initially augmented and subsequently depressed by apamin (1–10 nM) and (+)-tubocurarine (100–600 M). It is concluded that theI _SAH in visceral primary neurones may be due to a long-lasting increase in K⁺ conductance caused by an increase in the concentration of intracellular Ca²⁺, resulting from Ca²⁺ entry during the depolarizing command pulse.     

Study of induction of activation of human peripheral blood mononuclear cells with a non-activating form of anti-CD3 MoAb in autoimmune thyroid disease (AITD).

Anti-CD3 (OKT3) MoAb is a mitogenic agent which activates lymphocytes. We have studied the effects of murine anti-human OKT3 MoAb (IgG1) alone or in combination with IL-2, human thyroglobulin (Tg) and thyroperoxidase (TPO) antigens on the proliferation of whole peripheral blood mononuclear cells (PBMC) (including monocytes) or subtypes (T, CD4+, CD8+, B) as measured by tritiated thymidine (3H-TdR) incorporation. B cell differentiation was studied by measuring numbers of IgG-secreting cells and specific anti-TPO/anti-Tg-secreting cells by SPOT ELISA. PBMC or lymphocyte subtypes, obtained from 45 patients with Hashimoto's thyroiditis (HT), 40 Graves' disease (GD) and 51 normal controls were cultured in 96 microtitre plates for 6 days in the presence of OKT3 MoAb at final concentrations 25-250 ng/ml, IL-2 15 U/ml, Tg and TPO (1 micrograms/ml). Then cultures were pulsed with 0.2 microCi 3H-TdR/well and incorporation was measured after 18 h. IgG and anti-TPO/Tg-secreting cells were detected at 7 days. Higher proliferative responses from whole PBMC preparations in response to any of the combinations including OKT3 MoAb were observed in the HT preparations, while the basal values were the lowest. IL-2 alone increased these responses markedly, but equally in all groups. IL-2 in combination with OKT3 had an additive effect on proliferation, with higher responses in HT. Tg and TPO antigens did not change these responses. Most HT preparations responded with their maximum proliferation to the lowest concentration of OKT3 MoAb (25 ng/ml), whereas in GD and control preparations of PBMC these responses were shifted to higher concentrations (250 ng/ml); even with those, proliferation was not so enhanced in controls when compared with HT and GD preparations. In contrast, the proliferative responses of T cells alone and subpopulations of CD8+ suppressor/cytotoxic cells were decreased in HT preparations compared with controls. Monocytes were necessary for proliferation. In the subpopulation of B cells (> 95% pure) and CD4+ helper/inducer cells, differences did not reach significance. In spite of the effect on proliferation, OKT3 MoAb only mildly but significantly increased the numbers of IgG-secreting cells in HT and GD preparations and did not stimulate synthesis of specific antibodies. Our data suggest that the increased proliferative responses of whole PBMC to OKT3 MoAb in HT preparations might be due to insufficient activation of T suppressor/cytotoxic cells.     

Effect of basic amino acids on susceptibility to carbapenems in clinical Pseudomonas aeruginosa isolates

We evaluated effects of medium composition, including basic amino acid content and pH, on susceptibility to carbapenems such as imipenem, panipenem and meropenem, in clinical isolates of Pseudomonas aeruginosa. Susceptibility to carbapenems was reduced by basic amino acids in the medium, while susceptibilities to ceftazidime and aztreonam were not. Among carbapenems, susceptibility to panipenem was most sharply reduced by addition of basic amino acids to 1:16 Mueller-Hinton agar (MHA). In 174 of 175 clinical isolates, MICs for carbapenems were affected to different degrees by medium composition. One isolate, in which MICs for carbapenems did not differ between MHA and 1:16 MHA, showed reduced production of porin (OprD). Our results suggest that susceptibility to individual carbapenems, especially panipenem, is difficult to evaluate based on MICs for other carbapenems determined on MHA. For a better prediction of antibiotic efficacy, it may be important to evaluate the susceptibility for each carbapenem individually.     

Two cases of a renal epithelial tumour resembling immature nephron

Summary Two cases of renal epithelial tumours are reported in females aged 46 and 66 years respectively. In spite of the large size of the tumours, neither invasive growth nor metastasis was observed. Histologically, the tumours were composed of immature epithelial cells forming tubules with abortive glomeruloid structures. Electron microscopy of tumour cells revealed poorly developed polarity and intracytoplasmic organelles. They showed similar immunohistochemical reactions to those of developing nephrons, particularly to those of the S-shaped body. The nuclear DNA content of the tumour cells was almost euploid. We conclude that the lesions were epithelial tumours of the kidney histologically mimicking developing renal parenchyma.     

The relationship of VEGF and PGE2 expression to extracellular matrix remodelling of the tenosynovium in the carpal tunnel syndrome

Tenosynovial thickening within the confined space of the carpal tunnel is thought to be the cause of the carpal tunnel syndrome (CTS). However, little is known about the pathological mechanism of tenosynovial thickening. In this study, the role of prostaglandin E(2) (PGE(2)) and vascular endothelial growth factor (VEGF) (two representative molecules that can induce oedema by increasing vascular permeability) was analysed in CTS by using immunohistochemistry and enzyme-linked immunosorptive assay (ELISA). Expression of these molecules was compared with the patients' clinical histories and a temporary increase in production of these molecules was found in cells within the vessels and synovial lining during the intermediate phase of the syndrome when the histology of the tenosynovium changes from oedematous to fibrotic. Statistical analysis clearly demonstrated that there is a close correlation between the expression of PGE(2) and VEGF. Furthermore, immunohistochemical analysis with anti-proliferating cell nuclear antigen (PCNA) revealed that the area with distinct VEGF expression closely matched the area where endothelial cells, vascular smooth muscle cells, and synovial lining cells proliferate. In contrast, despite marked alteration in the extracellular matrix (ECM) component of the tenosynovium, the fibroblasts responsible for most ECM framework production do not proliferate during any phase of CTS. Histological analysis demonstrated that angiogenesis takes place only during the intermediate phase. Since clusters of capillaries and arterioles are often surrounded by type III collagen-rich, disorganized, degenerate connective tissue, which contains fewer fibroblasts than normal, angiogenesis appears to take place as a part of a regenerative reaction that results in fibrosis. These findings strongly indicate that both PGE(2) and VEGF are expressed in the tenosynovium in CTS during the intermediate phase and induce the histological changes seen in the tenosynovium.