Detection of benzoquinone adducts to rat liver protein sulfhydryl groups using specific antibodies

Benzoquinone is an electrophilic metabolite of bromobenzene and other simple aromatic compounds of toxicological interest including benzene, phenol, hydroquinone, and acetaminophen. In reacting with proteins benzoquinone shows great selectivity for Michael addition to sulfhydryl groups and formation of S-(2,5-dihydroxyphenyl) protein adducts. To facilitate the specific detection and eventual isolation and identification of such adducted proteins, we prepared an antiserum capable of recognizing hydroquinone moieties by immunizing rabbits with keyhole limpet hemocyanin modified with 3-[2,5-dihydroxyphenyl)thio]propanoyl groups as haptens. The antiserum had a high titer and showed high specificity for hapten in competitive ELISA with hapten analogues. In Western blot experiments the antiserum detected not only synthetically haptenized control proteins but also several proteins from rat liver microsomes that had been incubated in vitro with [14C]bromobenzene. This binding was completely blocked by free hapten, showing that it was hapten-specific. Each of the microsomal protein bands detected in the Western blots also contained radioactivity, but not all radioactive protein bands reacted with antibody. This antiserum should prove useful in exploring the role of protein arylation by benzoquinone in cytotoxic responses to its metabolic precursors.     

Quantitative evaluation of flow patterns in perfusion cannulae by a new magnetic resonance imaging method

The arterial cannula is a critical part of any extracorporeal circulation system due to the high flow rates which must pass a small cross-sectional area, resulting in high blood velocities. The aim of this study was to examine whether high-field magnetic resonance scanning is applicable for detailed mapping of velocity fields around the tip of such arterial cannulae in vitro. The investigated cannula was an angled, open-tip traditional design aortic cannula with an internal tip diameter of 5.5 mm. The velocity fields were measured at two different flow rates (2 and 4 l/min) at various positions in the lumen and outside the cannula using magnetic resonance imaging (MRI). All three components of the velocity vectors were measured. The study showed that MRI can provide a clear quantitative visualization of the velocity field around the tip of arterial cannulae at lower flow rates. At higher flow rates it can provide information about localization of regions with turbulent or disturbed flow.     

The contribution of six chronic conditions to the total burden of mobility disability in the Dutch population

OBJECTIVES: This study assessed the proportions of the burden of mobility disability in the Dutch population that are attributable to musculoskeletal diseases, lung diseases, neurological disorders, heart diseases, diabetes, and cancer. METHODS: National survey data were analyzed with an elimination technique that combines the results of logistic regression analysis and the disease prevalence. RESULTS: Of the total prevalence of disability (20.5%), 33.7% can be attributed to these six chronic conditions. Musculoskeletal disorders account for the major part, whereas the contribution of cancer is very small. CONCLUSIONS: The potential benefits of effective curative or preventive treatments for chronic conditions, in terms of reduction of the disability burden in the population, are limited.     

Denaturation and reactivation of dimeric human glutathione reductase--an assay for folding inhibitors

In response to a Department of Health, England, circular encouraging policies of named voluntary antenatal HIV antibody testing, one West Midlands health authority in England introduced a policy of raising the issue proactively at the first antenatal attendance. In order to facilitate this policy a short staff education programme was provided for midwives. This paper reports on part of a study which aimed to evaluate the impact of the HIV awareness training programme. A sample of midwives (n = 65) was randomly selected for inclusion in the study. Thirty-three had attended training and 32 had not. Data were collected using a self-administered questionnaire exploring knowledge of aetiology of HIV/AIDS, knowledge of transmission, knowledge of obstetric and paediatric HIV, attitudes to HIV, issues related to antenatal HIV antibody testing and opinions about the HIV awareness training programme. Results indicated no significant difference in levels of knowledge or in attitude between those who had attended the training programme and those who had not. Similarly, no significant difference was found in terms of how midwives would react to women requesting HIV antibody testing. Many of the results contradict the current literature and as a conclusion it is suggested that there is a need to review HIV-related training for midwives.     

Subcellular localization of myosin-V in the B16 melanoma cells, a wild-type cell line for the dilute gene

The discovery that the dilute gene encodes a class V myosin led to the hypothesis that this molecular motor is involved in melanosome transport and/or dendrite outgrowth in mammalian melanocytes. The present studies were undertaken to gain insight into the subcellular distribution of myosin-V in the melanoma cell line B16-F10, which is wild-type for the dilute gene. Immunofluorescence studies showed some degree of superimposed labeling of myosin-V with melanosomes that predominated at the cell periphery. A subcellular fraction highly enriched in melanosomes was also enriched in myosin-V based on Western blot analysis. Immunoelectron microscopy showed myosin-V labeling associated with melanosomes and other organelles. The stimulation of B16 cells with the alpha-melanocyte-stimulating hormone led to a significant increase in myosin-V expression. This is the first evidence that a cAMP signaling pathway might regulate the dilute gene expression. Immunofluorescence also showed an intense labeling of myosin-V independent of melanosomes that was observed within the dendrites and at the perinuclear region. Although the results presented herein are consistent with the hypothesis that myosin-V might act as a motor for melanosome translocation, they also suggest a broader cytoplasmic function for myosin-V, acting on other types of organelles or in cytoskeletal dynamics.     

Pharmacokinetics of florfenicol in cerebrospinal fluid and plasma of calves

Florfenicol, a fluorinated analog of thiamphenicol, is of great value in veterinary infectious diseases that formerly responded favorably to chloramphenicol. In view of the treatment of meningitis in calves, we studied its pharmacokinetics in the cerebrospinal fluid (CSF) and plasma of six animals. To this end, a new high-performance liquid chromatography method was developed which, unlike previous ones, uses solid-phase instead of double-phase extraction to isolate the drug. After a single intravenous dose of 20 mg/kg of body weight, a maximum concentration in CSF of 4.67 +/- 1.51 microg/ml (n = 6) was reached, with a mean residence time of 8.7 h. The decline of florfenicol in both CSF and plasma fitted a biexponential model with elimination half-lives of 13.4 and 3.2 h, respectively. Florfenicol penetrated well into CSF, as evidenced from an availability of 46% +/- 3% relative to plasma. The levels remained above the MIC for Haemophilus somnus over a 20-h period. Our results provide evidence indicating the effectiveness of florfenicol in the treatment of bacterial meningitis of calves.