Phospholipase A2 in human placental serum

Intervillous blood was collected from term placentae at delivery, and sera were tested for phospholipase A2 under various experimental conditions. Enzyme activity was found to develop upon extended storage in the cold or at 37 degrees C. The enzyme is reversibly inhibited by dithiothreitol, requires Ca++ ions for activity, and tolerates various detergents. The apparent molecular weight is 42 kDa. In all these parameters the serum enzyme behaves similar to the 42 kDa phospholipase A2 which we recently purified to homogeneity from thoroughly washed placental tissue. Serum phospholipase A2 appears to be generated by proteolytic processing from a slightly larger inactive precursor which was detected immunochemically. Most likely this protein originates from fetal cells and may be released by membrane damage. We conclude that both placental serum and tissue harbour a novel type of phospholipase A2 which is distinct from cytosolic and secretory phospholipases A2. Preference for arachidonate containing substrate suggests a role in eicosanoid production within gestational tissues.     

Substantial narrowing of the Niemann-Pick C candidate interval by yeast artificial chromosome complementation

Niemann-Pick disease type C (NP-C) is an autosomal recessive lipidosis linked to chromosome 18q11-12, characterized by lysosomal accumulation of unesterified cholesterol and delayed induction of cholesterol-mediated homeostatic responses. This cellular phenotype is identifiable cytologically by filipin staining and biochemically by measurement of low-density lipoprotein-derived cholesterol esterification. The mutant Chinese hamster ovary cell line (CT60), which displays the NP-C cellular phenotype, was used as the recipient for a complementation assay after somatic cell fusions with normal and NP-C murine cells suggested that this Chinese hamster ovary cell line carries an alteration(s) in the hamster homolog(s) of NP-C. To narrow rapidly the candidate interval for NP-C, three overlapping yeast artificial chromosomes (YACs) spanning the 1 centimorgan human NP-C interval were introduced stably into CT60 cells and analyzed for correction of the cellular phenotype. Only YAC 911D5 complemented the NP-C phenotype, as evidenced by cytological and biochemical analyses, whereas no complementation was obtained from the other two YACs within the interval or from a YAC derived from chromosome 7. Fluorescent in situ hybridization indicated that YAC 911D5 was integrated at a single site per CT60 genome. These data substantially narrow the NP-C critical interval and should greatly simplify the identification of the gene responsible in mouse and man. This is the first demonstration of YAC complementation as a valuable adjunct strategy for positional cloning of a human gene.     

Refractory IBD: medical management

Refractory inflammatory bowel disease (IBD) can be defined as persistent acute symptomatic disease despite anti-inflammatory therapy or as chronically active disease requiring continuous treatment for relief of symptoms. Treatment options include azathioprine (AZA), 6-mercaptopurine (6-MP), methotrexate (MTX), cyclosporine (CYA), and experimental therapies that are cytokines or cytokine antagonists. AZA and 6-MP have identical actions in IBD. 6-MP is effective in about 75% of patients with inflammatory Crohn's disease. The mean time until the onset of action is 3.1 months. AZA is effective in ulcerative colitis as a steroid-sparing agent. Side-effects occur in 10-15% of patients on AZA or 6-MP for IBD. MTX induces symptomatic remission in about 40% of patients with Crohn's disease. The potential for hepatic fibrosis from MTX is a concern. CYA appears effective in the acute management of severe ulcerative colitis. CYA has not proven useful in the long-term management of Crohn's disease. Potentially serious side-effects include hypertension and renal insufficiency. The cytokine antagonist, anti-tumor-necrosis-factor-alpha antibody, and the anti-inflammatory cytokine, interleukin 10, appear promising for the treatment of Crohn's disease.     

Developmental toxicity of 1,2-dichloropropane (PDC) in rats and rabbits following oral gavage

The ST-16 antigenic specificity of the HLA-B locus is defined as a B39 variant of Mexican-Americans. Nucleotide sequencing of cDNA shows the ST-16 allele (B*3905) differs from B*39011 by a single substitution that substitutes tyrosine for aspartic acid at position 74 of the mature class I heavy chain. The complete coding region sequence for the common caucasoid allele encoding the B38 antigen has been determined. This B*3801 allele differs from B*3802 at two nucleotide substitutions within the Bw4 sequence motif. B*3801 and B*3802 may have been derived independently from B*39011 by conversion events with B alleles donating distinctive Bw4 motifs. A novel allele B*39022 derived from a Colombian Indian differs from the B*39021 allele of Japanese origin at two widely separated silent substitutions. Comparison of sequences for the known B16 alleles suggest that B*39021 and B*39022 were independently derived by recombination from B*39013 and B*39011 respectively.     

Pretreatment hemoglobin level influences local control and survival of T1-T2 squamous cell carcinomas of the glottic larynx

PURPOSE: A number of reports have documented the relationship between pretreatment hemoglobin level and local control and/or survival in the treatment of cervix, bladder, and advanced head and neck tumors. Consideration of correcting anemia before initiation of radiation therapy may prove increasingly important as clinical trials use intensive induction chemotherapy in the treatment of head and neck carcinomas. Neoadjuvant chemotherapy may produce anemia, which in turn may reduce the effectiveness of subsequent irradiation. MATERIALS AND METHODS: One hundred nine patients with T1-2N0 squamous cell carcinoma of the glottic larynx were treated with definitive radiotherapy at the Fox Chase Cancer Center between June 1980 and November 1990. Follow-up times ranged from 26 to 165 months (median, 82). RESULTS: The 2-year local control rate for patients who presented with a hemoglobin level < or = 13 g/dL was 66%, compared with 95% for patients with a hemoglobin level more than 13 g/dL (P = .0018). The 2-year survival rate for patients with a hemoglobin level < or = 13 g/dL was 46%, compared with 88% for patients with a hemoglobin level more than 13 g/dL (P < .001). Cox proportional hazards regression analysis showed that hemoglobin level (P = .0016) was the only variable that significantly influenced local control (P = .0016) and survival (P < .0001). CONCLUSION: Patients who presented with hemoglobin levels more than 13 g/dL had significantly higher local control and survival rates. The strong apparent correlation between hemoglobin level, local control, and survival supports consideration of correcting anemia before initiation of radiation therapy.     

Alcohol intake of P rats is regulated by muscarinic receptors in the pedunculopontine nucleus and VTA

The CtpA protein in the cyanobacterium Synechocystis 6803 is a C-terminal processing protease that is essential for the assembly of the manganese cluster of the photosystem II complex. When fused to different chloroplast-targeting transit peptides, CtpA can be imported into isolated spinach chloroplasts and is subsequently translocated into the thylakoid lumen. Thylakoid transport is mediated by the cyanobacterial signal peptide which demonstrates that the protein transport machinery in thylakoid membranes is functionally conserved between chloroplasts and cyanobacteria. Transport of CtpA across spinach thylakoid membranes is affected by both nigericin and sodium azide indicating that the SecA protein and a transthylakoidal proton gradient are involved in this process. Saturation of the Sec-dependent thylakoid transport route by high concentrations of the precursor of the 33-kDa subunit of the oxygen-evolving system leads to a strongly reduced rate of thylakoid translocation of CtpA which demonstrates transport by the Sec pathway. However, thylakoid transport of CtpA is affected also by excess amounts of the 23-kDa subunit of the oxygen-evolving system, though to a lesser extent. This suggests that the cyanobacterial protein is capable of also interacing with components of the deltapH-dependent route and that transport of a protein across the thylakoid membrane may not always be restricted to a single pathway.     

Determination of dopexamine hydrochloride in human blood by high-performance liquid chromatography with electrochemical detection

A method is described for the determination of dopexamine hydrochloride at concentrations of 5 to 100 ng/ml in human blood using electrochemical detection. The method uses a Hypersil ODS column and a mobile phase containing heptane sulphonate, orthophosphoric acid, diisopropylamine and disodium EDTA. Blood samples are stabilised immediately after collection by the use of dipotassium EDTA and a high concentration of sodium metabisulphite. The sample preparation procedure consists of a simple de-proteinisation with perchloric acid. The method is accurate, with inter-assay accuracies ranging from 100 to 104%, and is free of interference by blood from different individuals. Known and potential metabolites of dopexamine hydrochloride and a wide range of drugs do not interfere with the method. The method is precise with inter-assay coefficients of variation of 10.6% at 5 ng/ml and of less than 4.2% at higher concentrations. Stabilised blood samples may be stored for over six months at -25 degrees C prior to analysis.