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Biomedical subjects

C A Lewis

Publications and source records attributed to C A Lewis.

139 records · Page 8Linked to original sources
PubMedDate not supplied

Early and late phase bronchoconstrictions in conscious sensitized guinea-pigs after macro- and microshock inhalation of allergen and associated airway accumulation of leukocytes.

Guinea-pigs were sensitized by i.p. injection of 10 micrograms OA and 100 mg aluminium hydroxide in 1 ml normal saline. Fourteen to twenty-one days after sensitization, animals were exposed to macroshock (1% OA for 2 min) or microshock (0.01% for 60 min) inhalation challenges with OA. Animals were protected against fatal anaphylaxis in the case of macroshocks with mepyramine (30mg/kg i.p.) 30 min before exposure. Specific airway conductance (sGaw) was measured in conscious animals by whole body plethysmography at intervals up to 72 h after challenge. An early phase bronchoconstriction peaked significantly (P < 0.05) at 15 min after both macroshock and microshock OA exposures, with maximum falls in sGaw of 70.8 +/- 3.8 and -40.0 +/- 5.9%, respectively. These had resolved after 5 h. A late phase bronchoconstriction peaked variably between 17 and 24 h: the mean peak falls in sGaw after the macro- and microshock challenges were significantly different from baseline (P < 0.05), at -21.6 +/- 3.7 and -38.0 +/- 3.9%, respectively. Control exposures of OA-sensitized guinea-pigs to saline for either 2 or 60 min, in place of OA, produced no significant variation in sGaw values over the predicted early and late phases. Bronchoalveolar lavage (BAL) performed at 5 or 24 h after OA challenge revealed significant increases in total cell numbers (P < 0.05) at 5 and 24 h after the OA macroshock challenge and at 24 h after the microshock, compared with saline challenges. Differential cell counts showed a significant (P < 0.05) increase in the proportion of neutrophils at 5 h and of neutrophils and eosinophils at 24 h after the macroshock exposure to OA, compared with saline controls. A significant (P < 0.05) increase in the proportion of eosinophils also occurred in BAL fluid at 24 h after microshock OA challenge. Neutrophils, however, did not alter at 24 h, yet a late phase bronchoconstriction was recorded. Thus, macroshock (with mepyramine cover) and microshock (without mepyramine cover) OA challenges result in both early and late phase bronchoconstrictions. The late phase is associated with influx of eosinophils in both models but neutrophils only appear after the macroshock, indicating that late phase responses may not involve neutrophil infiltration to the airways.

Administration, Inhalation↗
PubMedDate not supplied

The cervical cap: an alternative contraceptive.

The cervical cap is a convenient, inexpensive, nonhormonal and non-invasive contraceptive method. This method has potential for better effectiveness if custom-fit caps are manufactured. As more health care providers become knowledgeable in the use of the cap, more women will become aware of this contraceptive method as an alternative to oral contraceptives and intrauterine devices. Research is needed to document the most accurate method of cervical cap fitting and the effectiveness rate of the cervical cap. Nurse practitioners who counsel patients and fit them for caps are in the perfect position to start doing this research.

Contraceptive Devices, Female↗
PubMedDate not supplied

Influence of solid support, solvent and coupling reagent on the head-to-tail cyclization of resin-bound peptides.

Head-to-tail cyclization of peptides attached to insoluble supports by means of the side chains of aspartic acid or glutamic acid allows the rapid synthesis of cyclic peptides of widely varied amino acid sequence. However, two side reactions dramatically reduce the yield of the desired compound; these are (1) interpeptide condensation that creates dimers, trimers and higher-order oligomers and (2) racemization of the C-terminal residue. A comparison was made between benzotriazoyloxy-tris-(dimethyl-amino)phosphonium hexafluorophosphate (BOP) and diisopropylcarbodiimide (DIPCDI) as cyclization reagents on kieselguhr-supported polydimethylacrylamide, chloromethyl-PolyHipe, and two commercially available polystyrene supports using DMF, CH2Cl2 and THF as cyclization solvents. Both of the side reactions are dependent on the amino acid sequence, the reagent used to couple the ends of the peptide and the solid support.

Amino Acid Sequence↗