On the role of Ca2+ in the toxicity of alkylating and oxidizing quinone imines in isolated hepatocytes

The cytotoxicity of acetaminophen (paracetamol) has been shown to be associated with a disruption of intracellular Ca2+ homeostasis caused by the interaction of its metabolite N-acetyl-p-benzoquinone imine (NAPQI) with hepatocyte thiols [Moore, M., et al. (1985) J. Biol. Chem. 260, 13035-13040]. Inasmuch as NAPQI can both covalently bind to thiols and oxidize thiols, we investigated the effects of two dimethylated analogues of NAPQI, one of which (2,6-dimethyl-NAPQI) primarily binds to thiols and the other of which (3,5-dimethyl-NAPQI) primarily oxidizes thiols. Of the three compounds, 2,6-dimethyl-NAPQI decreased protein thiols to the greatest extent and also inhibited hepatocyte plasma membrane Ca(2+)-ATPase to the greatest extent. The 3,5-dimethylated analogue decreased protein thiols to the least extent and inhibited the plasma membrane Ca(2+)-ATPase to a lesser extent. The cytotoxicity of all three compounds was preceded by a sustained elevation in cytosolic Ca2+ as compared to the transient rise caused by the alpha-agonist phenylephrine. Again, the 2,6-dimethyl analogue was the most potent of the three compounds. The thiol reagent dithiothreitol (DTT), which reversed the inhibition of the Ca(2+)-ATPase and the rise in cytosolic Ca2+, also protected against cytotoxicity. Agents that are known to inhibit either Ca(2+)-dependent proteases or phospholipases significantly delayed the onset of cytotoxicity caused by NAPQI and its analogues. Our results suggest that both arylation and oxidation of protein thiols may result in the elevation of cytosolic Ca2+ and in cytotoxicity and that arylation of critical thiol groups appears to be the more lethal reaction.     

Kinetic and biologic properties of recombinant ChIFN-gamma expressed via CELO-virus vector.

In this study, a replicative fowl adenovirus serotype 1 (CELO) recombinant expressing chicken interferon-gamma (ChIFN-gamma) was constructed. In the engineered recombinant, the ChIFN-gamma gene was placed under the control of cytomegalovirus (CMV) promoter. The ChIFN-gamma expression cassette was inserted in the right end of the CELO genome (D fragment), which was able to carry the largest insertion of foreign DNA without affecting the replication functions of the vector. The recombinant ChIFN-gamma (rChIFN-gamma) produced in the CELO-virus expression system was characterized by comparing its biologic activities with that of rChIFN-gamma produced via the baculovirus expression system (Bac-ChIFN-gamma). CELO-ChIFN-gamma inhibited the replication of cytolytic virus in chicken embryo fibroblasts (CEFs) and activated macrophages in a better manner than did Bac-ChIFN-gamma . Moreover, the in vitro and in vivo stability of the CELO-derived rChIFN-gamma was considerably higher than that of the Bac-ChIFN-gamma. The CELO-ChIFN-gamma recombinant vector was able to replicate in vitro in the loghorn male hepatoma (LMH) hepatocyte cell line and to produce detectable levels of recombinant cytokine in supernatant as early as 90 min post-infection. Therefore, the CELO-virus expression system is an appropriate system for high-level expression of biologically active and stable ChIFN-gamma.     

Reliability and validity of the classification of death in general practice

The general practitioner in the Netherlands is solely responsible for assigning the natural causes of a patient's death when it occurs at home and for entering it on the certificate of death B, which is then forwarded to the CSO (Central Statistics Office). The CSO however, records the cause of death in the appropriate category of the ICD-9 of the WHO. The value of these data, therefore, depends upon the agreement between the general practitioner's cause of death and the CSO categories of causes of death. To assess the degree to which the CSO classification reflects the general practitioner's cause of death, form B from eight general practitioners practicing in Hoorn were compared with the classification of the CSO during a period of five years, 1979-83. There was a 65% (237/365) agreement between the classifications. Of the remaining 128 cases 68% (87/128) of the classification differences were caused by a wrongly described cause of death on the B certificate. In 32% (41/128) the classification rules of WHO made it hardly possible for the general practitioner to classify uncertain causes of death. The conclusions of this survey are that the quality of the statistics on causes of death will improve if the general practitioners are more careful with filling in the certificate of death B; the classification rules of the ICD-9 makes it possible to classify unknown causes of death; and if the certificate of death B becomes more 'user friendly'.     

Lupus vasculitis

Anatomical studies have demonstrated the high incidence of vasculitis in SLE, the appearances of which are variable and non-specific, ranging from necrotizing angiitis which is undistinguishable from periarteritis nodosa, to scarring lesions. Micro-angiitis is easily demonstrated in skin lesions and is also encountered to varying degrees in CNS, renal, cardiac, pulmonary and gastrointestinal localisations. Disease of large vessels is more rare and sometimes causes gangrene of the limbs. In SLE, vasculitis should be distinguished from thrombosis related to lupus anticoagulant and from atherosclerosis favoured by chronic steroid therapy but perhaps initiated by vascular deposits of immune complexes during the acute inflammatory stage. The treatment of lupic angiitis is mainly based on steroid therapy. The results are variable, probably due to the fibrous nature of some of the vascular lesions.     

Shunt nephritis with crescent formation

The case of a 17-year-old girl is reported, who presented shunt nephritis, 8 years after the ventriculo-atrial shunt insertion was made. Renal biopsy showed membranoproliferative glomerulonephritis. The symptoms of uremia mingled with those of chronic septic state. Persistent hypocomplementemia and cryoglobulinemia dominated the picture of the disease. At the beginning of the disease Staphylococcus aureus abunded in the blood culture. In spite of the therapy the general status of the patient declined steadily.     

Disseminated Candida infection syndrome in heroin addicts--dominance of a single Candida albicans biotype

Among 21 intravenous heroin abusers with cutaneous and ocular manifestations of disseminated Candida infection, a single C. albicans strain type (serotype A, biotype 153/7) was isolated from skin lesions in 14 cases. This suggests that central contamination of the heroin with C. albicans is less likely to be the source of infection than an endogenous source, and that one particular strain type is either better adapted than others to grow in the lemon juice used as a heroin solvent, or more likely than others to cause the specific pathology seen in these patients.