Phenotypic variability of lymphocyte populations in peripheral blood and lymph nodes from HIV-infected individuals and the impact of antiretroviral therapy. DATRI 003 Study Group. Division of AIDS Treatment Research Initiative

To study the mechanisms leading to diazepam (DZ)-induced chromosome loss, we evaluated the effect of the drug on the distribution of cytoplasmic and mitotic apparatus proteins using specific antibodies. The use of antibodies directed against dynein and kinetochores (CREST staining) suggested that chromosomes arranged in monopolar spindles were interacting with short fibers originating from the monopole. Interestingly, nearly 50% of DZ-induced monopolar mitoses showed a punctate staining of centrosomes when evaluated with an anti-gamma-tubulin antibody. The extent of phosphorylation of mitotic proteins was not affected by drug treatment, as shown by staining the cells with an antibody against mitotic phosphorylated proteins (MPM-2). After recovery of DZ, nearly 20% of anaphases were abnormal and mainly consisted of multipolar anaphases and lagging chromosomes; this was consistent with a high frequency of kinetochore-containing micronuclei as evaluated by CREST antibody staining in cells that had divided only once after drug removal, i.e. binucleate cells obtained by cytochalasin-B treatment. Our data confirmed that DZ is a powerful inducer of chromosome loss in cultured rodent cells. Moreover, our results indicate that DZ interfered with the correct assembly of centrosomes.     

Interaction of the two proteins of the methoxylation system involved in cephamycin C biosynthesis. Immunoaffinity, protein cross-linking, and fluorescence spectroscopy studies

Cephamycin C-producing microorganisms contain a two-protein enzyme system that converts cephalosporins to 7-methoxycephalosporins. Interaction between the two component proteins P7 (Mr 27,000) and P8 (Mr 32,000) has been studied by immunoaffinity chromatography using anti-P7 and anti-P8 antibodies, cross-linking with glutaraldehyde, and fluorescence spectroscopy analysis. Co-renaturation of the P7 and P8 polypeptides resulted in the formation of a protein complex with a molecular mass of 59 kDa, which corresponds to a heterodimer of P7 and P8. Glutaraldehyde cross-linking of the polypeptides after assembly of the protein complex showed the presence of a single heterodimer form that reacted with antibodies against P7 and P8. Each separate protein did not associate with itself into multimers. The P7.P8 complex co-purified by immunoaffinity chromatography from extracts of Nocardia lactamdurans and Streptomyces clavuligerus, suggesting that both proteins are present as an aggregate in vivo. Fluorescence spectroscopy studies of 5-methylaminonaphthalene-1-sulfonyl-P7 in response to increasing concentrations of P8 showed a blue shift in the fluorophore emission, indicating a conformational change of P7 in response to the interaction of P8 with an apparent dissociation constant of 47 microM. NADH showed affinity for the P7 component. The P7.P8 complex interacted strongly with the substrates S-adenosylmethionine and cephalosporin C, differently from that occurring with the separate P7 or P8 components, resulting in a strong blue shift in the fluorescence emission spectra of the complex.     

Neuro-otologic findings in the lightning-injured patient

To determine whether endoplasmic reticulum (ER) proliferation in hepatocytes after phenobarbital (PB) administration relates closely to cytochrome P-450 (P-450) increase, we have measured the amount of total P-450 per unit cytoplasmic volume (P-450 content) by microphotometry and estimated the area of ER per unit cytoplasmic volume (ER area) by morphometry in periportal, midzonal, and perivenular hepatocytes of mice injected daily with PB (100 mg/kg), or with PB (100 mg/kg) plus cobalt chloride (50 mg/kg) for three days. After injection of PB, the P-450 content and ER area increased in hepatocytes of the three sublobular zones. In mice treated with PB plus cobalt chloride, however, the ER area increased, but the P-450 content decreased or remained unchanged in hepatocytes of the three zones. We conclude that cobalt chloride inhibits the increase in total P-450 but has no effect on the proliferation of ER of hepatocytes in mice treated with PB, indicating a dissociation of ER proliferation and P-450 increase after administration of PB.     

Oxidation of phenolic compounds by lactoperoxidase. Evidence for the presence of a low-potential compound II during catalytic turnover

The lactoperoxidase (LPO)-catalyzed oxidation of p-phenols by hydrogen peroxide has been studied. The behavior of the enzyme differs from that of other peroxidases in this reaction. In particular LPO shows several catalytic intermediates during the catalytic cycle because of its capability to delocalize an oxidizing equivalent on a protein amino acid residue. In the phenol oxidation the enzyme Compound I species, containing an iron-oxo and a protein radical, uses the iron-oxo group at acidic pH and the protein radical in neutral or basic medium. Kinetic and spectroscopic studies indicate that the ionization state of an amino acid residue with pKa 5.8 +/- 0.2, probably the distal histidine, controls the enzyme intermediate forms at different pH. LPO undergoes inactivation during the oxidation of phenols. The inactivation is reversible and depends on the easy formation of Compound III even at low oxidant concentration. The inactivation is due to the substrate redox potential since the best substrate is that with lowest redox potential, while the worst substrate has the highest potential. This strongly indicates that Compound II, formed during catalytic turnover, has a low redox potential, making easier its oxidation by hydrogen peroxide to Compound III. The dependence of LPO activity on the phenols redox potential suggests that the protein radical where an oxidizing equivalent can be localized is a tyrosyl residue.     

Vagal regulation during bottle feeding in low-birthweight neonates: support for the gustatory-vagal hypothesis

BACKGROUND AND PURPOSE: Linear accelerators equipped with multileaf collimators (MLCs) are becoming more common and are widely available from most commercial manufacturers. There is a need to ensure they retain their commissioning specification using a preventative maintenance and quality control (QC) programme. This paper considers the design criteria of the Philips MLC which are important to the production of a comprehensive quality control programme. MATERIALS AND METHODS: The specific QC problems related to MLCs are identified as the positional accuracy of the leaves and their relationship to the back-up collimators, leakage considerations, the relationship of X-ray to light field and the influence of gravity on the positioning and leakage characteristics of the leaves. These problems are considered in relation to the general design considerations of the MLC, and methods of performing routine quality control checks are discussed. RESULTS AND CONCLUSIONS: The introduction of MLCs into clinical use results in new QC procedures being developed but it can be concluded that for the Philips MLC only an extra 30 min of QC time is needed per month and that its use has added little to the general down-time of this department.     

Differences in polymeric proteins among grains in spring wheat spikes

A uniform amount and size distribution of polymeric proteins within grains in a spike might determine the stability of wheat quality. Two cultivars were grown to maturity in solution culture in a climate chamber. Nitrogen (N) in the form of nitrate was added daily and replaced with ¹⁵N before harvest. Plants were harvested during grain development. Protein composition and relationships of labelled N in grains from different spikelets within the spike were determined. Higher percentages of large unextractable polymeric proteins (%‐LUPP) and total unextractable polymeric proteins (%‐TUPP) were found in the lower‐ and uppermost spikelets in the spike compared with the middle ones for cv. WL, but not for cv. Sport. Both cultivars showed variations in the percentage of large unextractable monomeric proteins (%‐LUMP) and total SDS‐extractable protein (Tote) in the spikelets within the spike. The amount of total SDS‐unextractable protein (Totu) did not vary for either of the cultivars. The spikelets within the spike showing high and low %‐LUMP and Tote at maturity showed a similar behaviour shortly after flowering in cv. WL, but not in cv. Sport. The N concentration of SDS and sonicated extracts varied along the spikelets of the spike for both cultivars. The atom‐% excess ¹⁵N decreased in cv. Sport SDS‐extractable and ‐unextractable proteins and cv. WL albumins + globulins, gliadins and glutenins from grains at different spikelet positions along the spike. Copyright © 2005 Society of Chemical Industry     

Preventive health care for children

This article discusses immunization, development, vision, blood pressure, dentition, behavioral, and environmental screening for preschool children. The authors then discuss screening for children in the early school years. Injury and violence prevention and topics of sexuality for the preadolescent are also presented.     

Separating group supervision from group therapy: Avoiding epistemological confusion.

Comments on M. T. Riva and J. A. Erickson's (see record 1996-09446-001) article examining group supervision practices in psychology predoctoral internships. The author argues that extant research in the area of group supervision has already provided evidence that suggests therapy-based group supervision environments or processes are likely not effective approaches to use with trainees. It is concluded that approaching group supervision primarily as a process of learning that is best informed by pedagogy, rather than as an activity similar to group therapy in its processes and goals, may assist supervisors and researchers in finding effective and ethical methods to train psychology students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)