Determination of orthophosphoric and orthophosphorous acids in the workplace air using ion chromatography

The authors elaborated a method measuring air level of orthophosphorous and orthophosphoric acids by means of ion chromatography within the range of 0.1-25 mg/cu m. The samples are extracted through concentration on a filter. The analysis regime includes depression of the background levels. The separating column (4 x 200 mm) is filled with anion exchanger BT IAN, the suppressing column (6 x 150 mm) is filled with cation exchanger Dowex 50 x 8, the elutriating agent is 1.5 mM of sodium carbonate, the detector is conductometric. Minimal amounts of ions that could be detected in the analyzed solution are 7-10 ng (HPO32-), 10-15 ng (HPO 42-). The method is designed to analyze the air of workplace.     

Chemistry of the pyrrolo[1,2-alpha]benzimidazole antitumor agents: influence of the 7-substituent on the ability to alkylate DNA and inhibit topoisomerase II

This study addresses the influence the 7-substituent on the cytotoxicity of pyrrolo[1,2-alpha]-benzimidazole quinones possessing a 6-aziridinyl group (PBIs) and a 6-acetamido group (APBIs). Reduction of a PBI to the aziridinyl hydroquinone results in both nucleophile trapping (alkylation) and 1,5-sigmatropic shift reactions. The latter process is essentially an internal redox reaction wherein the hydroquinone causes reductive opening of the aziridinyl ring. The 7-substituent controls the fate of the aziridinyl ring by means of steric and electronic effects. An electron-rich 7-substituent favors the 1,5-sigmatropic shift reaction. If the 7-substituent distorts the 6-aziridinyl group from the conformation required for the 1,5-sigmatropic shift, then nucleophile trapping occurs. The 7-methyl substituent results in significant nucleophilic trapping, and the 7-unsubstituted and 7-methoxy substituents favor the 1,5-sigmatropic reaction. Thus, the 7-methyl PBIs show the most cytotoxicity of the analogues studied. The APBIs are cytotoxic only as quinones, and reduction to the hydroquinone results in loss of activity. Consistent with this observation, the change from 7-methyl to the more electron-rich 7-methoxy results in a substantial loss of APBI cytotoxicity as well as decreased topoisomerase II inhibition. The mechanism of inhibition is thought to involve the interacalation of only electron deficient APBIs into DNA.     

Genomic imprinting in the brain

Biopsies of cervix uteri from 166 patients with benign and malignant lesions (12 normal, 48 inflammatory lesion, 6 adenocarcinoma, 2 adenosquamous carcinoma and 98 from squamous cell carcinomas) were studied histochemically. The stains used were PAS with/without diastase, AB/PAS (pH 2.5) and OR/AB. In inflammatory lesions neutral mucin was predominent which was replaced by sialomucin and sulphomucin in endocervical polyps. In malignant lesions sulphomucin was predominent. Seventeen percent cases of squamous cell carcinomas needed reclassification after mucin staining. Of the fourteen large cell non-keratinizing squamous cell carcinomas, 12 were reclassified as squamous cell carcinoma with mucin secretion and 2 as adenosquamous carcinoma. One case of small cell non-keratinizing squamous cell carcinoma was reclassified as moderately differentiated adenocarcinoma. None of the keratinizing carcinomas had evidence of mucin secretion. Mucin histochemistry should be done routinely on non-keratinizing squamous cell carcinomas to pick up more cases of carcinoma with evidence of mucin secretion which can be missed on routine haematoxylin and eosin stains. Such carcinomas are known to pursue a more aggressive clinical course and have a poorer prognosis than non-mucin secreting type of squamous cell carcinoma.     

The activity of acid phosphatase and its isoenzymes in patients with food poisonings

Changes in the activity of acid phosphatase (AP) and its isoenzymes (tartrate-insensitive AP and formalin-insensitive AP) were investigated in patients with food poisoning in the course of the disease. The activity of AP and its isoenzymes in the serum started to grow in early convalescence and reached maximum in late convalescence. Total activity of AP in food toxic infections consists primarily of the activity of its platelet fraction. AP activity may serve as an additional criterion to predict vascular platelet involvement of hemostasis.     

B7 blockade prevents activation-induced cell death of thymocytes

Although both B7 and its counter-receptor CD28 are expressed in the thymus, the role of B7 in thymic selection is not clear. We investigated the role of B7 in intrathymic deletion of antigen-specific T cells using a TCR transgenic model specific for antigen ovalbumin (OVA) and H-2Ad. Intraperitoneal injection of OVA induced apoptosis of thymocytes and drastic reduction of thymocyte numbers. This was significantly inhibited by co-injection of CTLA-4-Ig which blocks B7 co-stimulation. Deletion of T cells in the thymus following i.p. injection of OVA was associated with T cell pre-activation as demonstrated by T cell proliferation and cytokine production. Injection of CTLA-4-Ig blocked all these activation events and rescued thymocytes from activation-induced cell death. These results demonstrate that B7 is required for the activation-induced cell death of MHC class II-restricted thymocytes in vivo.     

Structural determination of N-2''-hydroxyoctadecenoyl-1-O-beta-D-glucopyranosyl-9-methyl-4, 8-sphingadienine from species of Aspergillus

The barrier function, surface biochemistry, and morphology of confluent monolayers of endothelial cells isolated from different segments of the bovine lung vasculature [microvessels (BLMVEC), vein (BPVEC) and artery (BPAEC)] were grown in culture and compared. A number of common cell surface proteins were identified along with two proteins of 46 and 48 kDa found exclusively on BPVEC. Lectin affinity chromatography revealed multiple glycosylation differences. The lectins, Arachis hypogaea (AHA) and Lycopersicum esculentum (LEA) agglutinins, interacted with several glycoproteins of BLMVEC but not of BPAEC. Bandeiraea simplicifolia (BS-1) and Caragana arborescens (CAA) agglutinins recognized several glycoproteins of BPVEC and BPAEC but not BLMVEC. Permeabilities were much lower for BLMVEC than BPAEC or BPVEC monolayers, with a range of about 16-fold less for sucrose to 2-fold less for albumin. Electron microscopy revealed that BLMVEC have a greater surface density of plasmalemmal vesicles (approximately 4-fold) and more extensively developed intercellular junctions with more focal membrane adhesion sites per junction (approximately 9-fold) than the other cells. We conclude that: i) BLMVEC monolayers form a much more restrictive barrier to molecular transport as a result of the tighter junctional formation; and ii) endothelial surface glycoproteins may be differentially glycosylated depending on their segmental location within the vasculature.     

Monoamine oxidase inhibitors inhibit [3H]quinpirole binding in rat striatal membranes

The paper deals with methods facilitating the preparation of oncospheres of the cestode, Hymenolepis diminuta, for experimental studies. Described in detail are procedures for the infection of the definitive hosts with the oncospheres; collection and artificial hatching of oncospheres; purification of hexacanths; preparation of extracts from the hexacanths; and preparation of hexacanths for electronmicroscopic studies.     

Transfected glucocorticoid receptor and certain GR fragments evoke cell death in malignant lymphoid, not myeloid cell lines

We compared the data from four growth hormone (GH) immunoassays for analyzing 24-h GH profiles in four apparently normal subjects and four obese subjects (508 serum samples). The detection limit was 0.02 microgram/L for one immunochemiluminometric assay (ICMA), 0.1 microgram/L for two IRMAs, and 0.4 microgram/L for one RIA. All GH pulses with a peak ICMA value > 1 microgram/L were detected by each of the other methods. Overall, the correlation coefficient between the values obtained with all four assays exceeded 0.90. However, for GH concentrations < or = 0.25 microgram/L, acceptable concordance (r2 > or = 0.80) was reached only between the ICMA and one IRMA; between the ICMA and the RIA, concordance was acceptable only for GH concentrations > or = 10 micrograms/L. In the normal subjects, the percentage of undetectable values was 0% with the ICMA but 29% with one of the IRMAs; in obese subjects, the corresponding values were 12% and 38%.     

Reproducibility of functional transcranial Doppler sonography in determining hemispheric language lateralization

BACKGROUND AND PURPOSE: Since functional transcranial Doppler ultrasonography (fTCD) allows convenient and fully automated quantification of language lateralization, it seems ideal for longitudinal studies of perfusion changes during deterioration as well as recovery of language functions. However, during serial examinations, the technical, stochastic, and physiological variabilities of cerebral blood flow velocities (CBFV) have to be considered. Therefore, before fTCD is accepted as a tool for evaluation of changes in lateralization in the diseased state, its reliability in healthy subjects needs to be determined. METHODS: We performed fTCD during a word generation task based on a previously validated technique with automated calculation of the averaged CBFV differences in the middle cerebral arteries providing an index of lateralization (LI). RESULTS: (1) The accuracy of the LI as assessed by the confidence interval was better than 1% of the mean hemispheric difference. (2) On repeated examination, LIs obtained from 10 subjects showed a high test-retest reproducibility (Pearson product moment correlation coefficient r = 0.95, P < 0.0001). (3) On 10 repeated assessments of LI in the same subject, no practice effects were detected. CONCLUSIONS: Functional TCD is a suitable and very robust tool for the longitudinal quantitative measurement of cerebral language lateralization.     

Effect of ethanol on platelet phospholipase A2

Platelet aggregation is known to be inhibited by ethanol, and this has been suggested to be one of the attenuating effects of ethanol in cardiovascular disease. Recent studies have implicated an inhibition of phospholipase A₂ induced arachidonic acid release, since the production of prostanoids that are formed from arachidonic acid and are involved in the aggregation process has been shown to be diminished by ethanol. Phospholipase A₂ is found in platelets in both a cytosolic form, from where it may translocate to the plasma membrane to release arachidonic acid, and in a secretory form which is released extracellularly upon activition. In the present study, the effect of ethanol on the secretion of phospholipase A₂ and on its activity was determined. It was found that ethanol inhibited trast, the activity of the cytosolic form of phospholipase A₂ was inhibited by ethanol.