PCR detection of amplified 132 bp repeats in Marek's disease virus type 1 (MDV-1) DNA can serve as an indicator for critical genomic rearrangement leading to the attenuation of virus virulence

A radioactive PCR test was developed that amplified the very virulent Marek's disease virus-1 (vvMDV-1) DNA sequence containing the 132 bp repeats. In apathogenic MDV-1 (CVI 988, Rispens), amplified DNA bands containing multiple copies of 132 bp repeats were identified. In the present study this PCR technique was used to monitor the passage level of vvMDV-1 in chicken embryo fibroblasts (CEF) in which the number of tandem 132 bp repeats was increased. It was found that at passage level 32 of vvMDV-1-B isolate, the 132 bp tandem repeat was already markedly amplified and its pattern resembled that of the MDV-1 (CVI 988, Rispens) vaccine virus DNA. In the vvMDV-1Z strain, amplification of the 132 bp repeat was not detectable at a similar passage level. The PCR test demonstrated that the apathogenic MDV-1 Md11/75c virus developed by extensive in vitro passaging has amplified 132 bp DNA repeats similar to those of the commercial vaccine virus (CVI 988, Rispense). It was also found that the pattern of viral RNA from infected cells detectable by Northern blot hybridization was markedly changed from a 2.4 kb RNA species in cells infected with vvMDV-1 viruses, to four RNA species (ranging from 2.2 to 4.4 kb) in cells infected with passage 32 of MDV-1-B strain, to a very large number of undefined RNA species synthesized in cells infected with attenuated MDV-1 viruses (CVI 988, Rispens and Md 11/75c).     

The response of ataxia-telangiectasia homozygous and heterozygous skin fibroblasts to neocarzinostatin

Skin fibroblast strains from patients with ataxia-telangiectasia(A-T) were recently reported to be hypersensitive to the antitumorantibiotic neocarzinostatin (NCS). In this study, the distinctintermediate degree of NCS sensitivity previously shown withtwo strains of A-T heterozygous fibroblasts was extended andconfirmed in an additional eight strains. A sensitivity baselinefor A-T heterozygous cells has thus been established and mayserve for the laboratory diagnosis of A-T heterozygotes, a cancer-pronepopulation. The response of A-T homozygous and heterozygouscells to NCS was further characterized by two molecular parameters,DNA repair synthesis and inhibition of DNA replication. Thepattern of dose response with regard to DNA repair synthesis,as assayed by the benzoylated naphthoylated DEAE cellulose chromatographymethod, was similar in normal, A-T homozygous and A-T heterozygouscells, although certain variability between strains was observedwith regard to the amount of repair incorporation. This findingcorrelates with a similar observation made with the same cellstrains following -irradiation. Inhibition of DNA synthesisfollowing NCS treatment was reduced in A-T homozygous cells,as compared to normal cells, but the "Inhibition resistant"component of DNA synthesis typically observed following treatmentwith low doses of X-rays or bleomycin was not observed withNCS. A-T heterozygous cells showed somewhat less inhibitionof DNA synthesis than normal cells following NCS treatment,although this difference was small and was not significant enoughto serve as an additional laboratory diagnostic aid. It is concludedthat the reduced inhibition of DNA synthesis, rather than reducedextent of DNA repair synthesis, correlates with the cellularhypersensitivity of A-T homozygous cells. This hypersensitivityseems to be observed primarily, if not exclusively, with DNAbreaking agents.     

Acute Cholecystitis Complicating Unrelated Disease: Etiological Considerations

The phenomenon of acute cholecystitis complicating an unrelated operation has been reported with increasing frequency, and may be preceded by a variety of operative procedures and a lack of previous biliary tract symptoms. Among eight such patients treated by us, seven developed acute cholecystitis postoperatively, and in one it was discovered during operation for bleeding duodenal ulcer. Two patients had undergone wide excision of the breast; two, highly selective vagotomy; one, nephrolithotomy; one, truncal vagotomy and gastroenterostomy; and one, left hemicolectomy and colostomy. In three patients, urgent cholecystectomy was performed, and four were treated conservatively with subsequent elective cholecystectomy. Histopathological studies revealed acute and chronic cholecystitis in all eight patients and cholelithiasis in four. One patient died in septic shock. Numerous contributing factors have been suggested, including hypovolemia and biliary stasis, as well as the presence of stones. It would appear that chronic cholecystitis or other biliary pathology, as found in our eight patients, is a major factor in the development of this manifestation.     

The dilemma of good clinical practice in the study of compromised standards of care

Four ethical issues loom over the study by Lieberman and colleagues - the absence of informed consent, the study being non-interventional in situations that typically call for life-saving interventions, the bias involved in doctors that study their own problematic practice and monopoly over intensive care unit triage, and ageism. We learn that the Israeli doctors in this study never make no-treatment decisions regarding patients in need of mechanical ventilation. They are complicit with botched standards of care for these patients, however, accepting without much doubt an ethos of scarce resources and poor managerial habits. The main two practical lessons to be taken from this study are that, for patients in need of mechanical ventilation, compromised care is better than a policy of intubation only when the intensive care unit is available, and that vigorous efforts are needed in order to extirpate ageism.     

Influence of chemical structure on hypersensitivity reactions induced by antiepileptic drugs: the role of the aromatic ring.

OBJECTIVE: Antiepileptic drugs (AEDs) can cause various 'idiosyncratic' hypersensitivity reactions, i.e. the mechanism by which AEDs induce hypersensitivity is unknown. The aim of this study was to assess whether the presence of an aromatic ring as a commonality in chemical structures of AEDs can explain symptoms of hypersensitivity. METHODS: Between January 1985 and January 2007, all adverse drug reactions (ADRs) reported to the Netherlands Pharmacovigilance Centre Lareb related to AEDs as suspected drugs were included in this study. ADRs were analysed using a case/non-case design. Cases were defined as those patients with ADRs involving symptoms of hypersensitivity. Non-cases were patients with all other ADR reports. Symptoms of hypersensitivity were classified according to the Gell and Coombs classification (type I-IV) and the organ involved (e.g. cutaneous, hepatic). AEDs were classified as aromatic anticonvulsant if their chemical structure contained at least one aromatic ring. All other AEDs were classified as non-aromatic. We assessed the strength of the association between aromatic AEDs versus non-aromatic AEDs and reported hypersensitivity reactions with logistic regression analysis and expressed these as reporting odds ratios (RORs). RESULTS: In total, 303 cases of hypersensitivity associated with the use of AEDs were reported. Aromatic AEDs were suspected in 64.4% of these reports versus 41.3% (574/1389) of the non-hypersensitivity reports. A significant ROR of 2.15 (95% CI 1.63, 2.82) was found for aromatic AEDs and all hypersensitivity reactions. Aromatic AEDs were significantly associated with immunoglobin E-mediated type I hypersensitivity reactions (ROR 2.15; 95% CI 1.23, 3.78) and T-cell-mediated type IV reactions (ROR 6.06; 95% CI 3.41, 10.75). Type II and III reactions did not show an association. Cutaneous symptoms represented 39.9% of the hypersensitivity-related ADRs. Aromatic AEDs were significantly associated with cutaneous hypersensitivity reactions (ROR 5.81; 95% CI 3.38, 9.99). CONCLUSION: This study confirms that the presence of an aromatic ring as a common feature in chemical structures of AEDs partly explains apparent 'idiosyncratic' hypersensitivity reactions. Symptoms of hypersensitivity were reported twice as frequently with aromatic AEDs than with non-aromatic AEDs. Strong associations for aromatic AEDs versus non-aromatic AEDs were found for T-cell-mediated (type IV) reactions, as well as for cutaneous reactions.