Apoptosis: molecular regulation of cell death

This article focuses on the few disorders that produce chronic cholestasis in infants and children. Cholestasis is defined, and a framework for thinking about pathophysiology is provided. Medical management is discussed in the context of the consequences and complications of chronic cholestasis. The limited differential for chronic cholestasis is discussed, and approaches to diagnosis and management of specific disorders are provided.     

Prevention of traffic accidents

To inform nursing professionals about their role in the prevention of traffic accidents, a grave health-related problem, is the purpose of this article. To begin with, factors which can deteriorate one's capacity to drive vehicles, and over which nursing professionals can intervene, will be presented. These factors include alcohol, other drugs, medicines, individual morbidity, the factor of aging and the use of security devices. A special reference will be made about widely used medicines. Finally the role that a nurse can fulfill will be explained. This role can be directed to various sections of the general public, be of varying natures, be exercised with greater or lesser ease, and lastly can have more or less effect upon those to whom it is destined.     

Oxidative damage and metabolic dysfunction in Huntington's disease: selective vulnerability of the basal ganglia

The etiology of the selective neuronal death that occurs in Huntington's disease (HD) is unknown. Several lines of evidence implicate the involvement of energetic defects and oxidative damage in the disease process, including a recent study that demonstrated an interaction between huntingtin protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Using spectrophotometric assays in postmortem brain tissue, we found evidence of impaired oxidative phosphorylation enzyme activities restricted to the basal ganglia in HD brain, while enzyme activities were unaltered in three regions relatively spared by HD pathology (frontal cortex, parietal cortex, and cerebellum). Citrate synthase-corrected complex II-III activity was markedly reduced in both HD caudate (-29%) and putamen (-67%), and complex IV activity was reduced in HD putamen (-62%). Complex I and GAPDH activities were unaltered in all regions examined. We also measured levels of the oxidative damage product 8-hydroxydeoxyguanosine (OH8dG) in nuclear DNA, and superoxide dismutase (SOD) activity. OH8dG levels were significantly increased in HD caudate. Cytosolic SOD activity was slightly reduced in HD parietal cortex and cerebellum, whereas particulate SOD activity was unaltered in these regions. These results further support a role for metabolic dysfunction and oxidative damage in the pathogenesis of HD.     

Two independent internal ribosome entry sites are involved in translation initiation of vascular endothelial growth factor mRNA

The mRNA of vascular endothelial growth factor (VEGF), the major angiogenic growth factor, contains an unusually long (1,038 nucleotides) and structured 5' untranslated region (UTR). According to the classical translation initiation model of ribosome scanning, such a 5' UTR is expected to be a strong translation inhibitor. In vitro and bicistronic strategies were used to show that the VEGF mRNA translation was cap independent and occurred by an internal ribosome entry process. For the first time, we demonstrate that two independent internal ribosome entry sites (IRESs) are present in this 5' UTR. IRES A is located within the 300 nucleotides upstream from the AUG start codon. RNA secondary structure prediction and site-directed mutagenesis allowed the identification of a 49-nucleotide structural domain (D4) essential to IRES A activity. UV cross-linking experiments revealed that IRES A activity was correlated with binding of a 100-kDa protein to the D4 domain. IRES B is located in the first half of the 5' UTR. An element between nucleotides 379 and 483 is required for its activity. Immunoprecipitation experiments demonstrated that a main IRES B-bound protein was the polypyrimidine tract binding protein (PTB), a well-known regulator of picornavirus IRESs. However, we showed that binding of the PTB on IRES B does not seem to be correlated with its activity. Evidence is provided of an original cumulative effect of two IRESs, probably controlled by different factors, to promote an efficient initiation of translation at the same AUG codon.     

Unintegrated circular HIV-1 DNA in the peripheral mononuclear cells of HIV-1-infected subjects: association with high levels of plasma HIV-1 RNA, rapid decline in CD4 count, and clinical progression to AIDS

We observed 36 HIV-infected patients to evaluate whether the presence of tandem 2-long terminal repeat circular unintegrated HIV-1 DNA (2-LTR) in peripheral blood mononuclear cells (PBMC) at baseline was associated with acceleration of HIV disease. Detection of 2-LTR at baseline correlated with high plasma HIV-1 RNA levels (p < .01), recovery of culturable HIV-1 from plasma (p = .02), and progression to AIDS during follow-up (p = .01). More patients with 2-LTR (68%) than without 2-LTR (31%) had a decline in CD4 levels of >50 cells/mm3 over the first 18 months of follow-up (p = .04), and the average annual CD4 decline was 35% in patients with 2-LTR compared with 16% in those without 2-LTR (p = 0.06). Detection of 2-LTR in PBMC at baseline was an independent predictor of high plasma HIV-1 RNA levels and subsequent CD4 cell decline in this cohort of patients with predominantly nonsyncytium-inducing (NSI) isolates at baseline. The presence of 2-LTR in PBMC appears to be reflective of ongoing HIV-1 replication, as measured by plasma HIV-1 RNA levels, and identifies persons at risk for immunologic and clinical decline.     

LacZ staining in paraffin-embedded tissue sections

Femora and tibiae of rats carrying leukemia from a LacZ-marked acute promyelocytic leukemia-derived leukemic cell line (LT12NL15) were decalcified using EDTA and routinely embedded in paraffin. Sections were used to develop for the first time an immunostaining method for LacZ, employing catalyzed reporter deposition (CARD) based on the deposition of biotinylated tyramine. This method was used to study homing and adhesion of leukemic cells.     

A theoretical model using mechanical principles to quantify the physical principles of balloon dilatation

RATIONALE AND OBJECTIVES: Balloon dilatation is a mechanical form of controlled injury used to alleviate vascular stenoses. Several factors influence successful angioplasty. Few mechanical models exist to illustrate the physical principles of balloon dilatation. METHODS: We used mechanical analysis of membrane stresses, along with Laplace's law, to determine a relation between balloon inflation and dilating pressures exerted by balloons in stenoses of varying severity, length, and eccentricity. The balloons were assumed to be perfectly inelastic and flexible. We also examined the resultant stresses in the lesion wall of concentric and eccentric stenoses from exertion of dilating pressures. RESULTS: Dilating pressures depend directly on maximal balloon inflation pressure and balloon diameter. Short, focal stenoses experience greater dilating pressures, which often are several multiples of the inflation pressure, than similarly narrowed longer lesions. CONCLUSION: Dilating pressures depend on inflation pressure, balloon diameter, and lesion severity.     

Screening for tyrosinaemia type I

AIMS: To assess the incidence of tyrosinaemia type I in the West Midlands Region, and the value of current neonatal screening programmes for phenylketonuria (PKU) for its detection. METHODS: Retrospective study of results from the PKU neonatal screening programmes in Birmingham (using plasma amino acid chromatography) and in the rest of the West Midlands (using the Guthrie microbiological assay for blood spot phenylalanine) was carried out between January 1985 and March 1994. Patients with tyrosinaemia I born in the region during the same period were identified from a regional database of patients with confirmed inherited metabolic disease. The study was carried out in a specialist children's hospital; the regional centre in the West Midlands for neonatal screening and investigation of inborn errors, and a supraregional centre for liver transplantation and management of paediatric liver disease. RESULTS: Amino acid chromatography showed increased tyrosine in 447 of 145,444 neonates born in Birmingham; this was still increased at 6 weeks of age in six cases. Five had tyrosinaemia I; the sixth had tyrosinaemia type III. Two others in whom amino acid chromatography was considered normal have since presented with tyrosinaemia I. Outside Birmingham, 525,151 children were screened using the Guthrie test. Five have presented clinically with tyrosinaemia I; screening did not contribute to diagnosis in any case. The incidence of tyrosinaemia I was 1 in 20,791 live births within Birmingham and 1 in 105,037 outside. Of the total 12 patients in the West Midlands with tyrosinaemia I, 10 (83%) were of non-oriental Asian ethnicity; the incidence of tyrosinaemia I was 3.7/10(6) head of population in this group and 0.04/10(6) in the rest of the population. CONCLUSIONS: Asians in the West Midlands have a high incidence of tyrosinaemia I. Neonatal PKU screening using amino acid chromatography may contribute to diagnosis and early treatment.