Small bowel and colon glucose absorption study in rats by an adaptation of Sols and Ponz method.

An adaptation of the Sols and Ponz method for the study of glucose intestinal absorption was developed by considering the special conditions of our line research. The glucose absorption was studied in proximal jejunum, distal ileum and distal colon in Wistar rat. The main adaptations in the method for successive absorptions with intestinal perfusions in vivo were the length of the intestinal segment and the change of the pumping system. The results are very similar to those obtained with the original method.     

Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.     

Effects of methotrexate-carcinoembryonic-antigen-antibody immunoconjugates on GW-39 human tumors in nude mice

Summary Methotrexate (MTX) was conjugated to an anti-carcinoembryonic antigen monoclonal antibody (NP2) by using amino-dextran as an intermediate carrier. The drug was chemically linked to amino-dextran (averageM _r = 40000), and the resulting MTX-dextran was then site-specifically attached to the carbohydrate moiety of the antibody. Athymic nude mice that carried human colonic GW-39 tumors (s. c.) were treated with the immunoconjugate. In this study, the specific conjugate caused a greater inhibition of the tumor growth than either free MTX or its conjugate with dextran and an irrelevant antibody. The intermediate MTX-dextran and the unlinked mixture of MTX-dextran with NP2 were both relatively ineffective in inhibiting tumor growth. The greatly reduced host toxicity permitted the use of the MTX-dextran-NP2 in a high-dose therapy of this tumor system.Supported in part by U.S.P.H.S. grant CA39 841 from the NIH     

Intraspecific variation in resistance to desiccation and climatic gradients in the distribution of the land snail Xeropicta vestalis

Land snails are subject to desiccating conditions in their terrestrial habitat. Our previous studies have revealed significant differences in resistance to desiccation among closely related species and among genera that share a similar life style, suggesting that the distribution pattern is correlated with the abiotic regime in its specific habitat. Our present study extends the scope of comparison to the intraspecific level, by examining the resistance to desiccation in five populations of Xeropicta vestalis , a Mediterranean-dwelling species that ranges from the 1000 mm to the 200 mm isohyet.
The resistance to desiccation varied among populations in correlation with the specific habitat of each population and with the north-to-south and the west-to-easl climatic gradients. Furthermore, in one case it exceeded the resistance of other, desert-dwelling species ( Trochoidea simulata, Sphincterochila zonata). We suggest that, in spite of its physiological capacity to invade deserts, X. vestalis is prevented from doing so because it is an annual, semelparous species. The Negev Desert is an unpredictable environment, susceptible to year-to-year fluctuations to such an extent that one rainless year would wipe out all its populations.     

Cyclic AMP and adenylate cyclase activators stimulate Trypanosoma cruzi differentiation

A chemically defined in vitro differentiating condition was used to study the potential role of cyclic AMP (cAMP) and adenylate cyclase activators on the transformation of Trypanosoma cruzi epimastigotes to the infective metacyclic trypomastigotes (metacyclogenesis). It was observed that both addition of cAMP analogs or adenylate cyclase activators to the differentiating medium stimulated the transformation of epimastigotes to metacyclic trypomastigotes. These results were further corroborated by showing that inhibitors of cAMP phosphodiesterase were stimulatory while activators of this enzyme inhibited the metacyclogenesis process. On the other hand, inhibitors of calmodulin inhibited the transformation of epimastigotes to metacyclic trypomastigotes, suggesting that T. cruzi adenylate cyclase might be activated by calmodulin. In addition, the results strongly suggest that guanine nucleotide binding proteins are involved in T. cruzi adenylate cyclase activation. This system may be useful for studying cell differentiation mechanisms in eukaryotes.     

Inhibition of prostaglandin biosynthesis by SQ 28,852, a 7-oxabicyclo[2.2.1]heptane analog

7-Oxabicyclo[2.2.1]heptane analogs of prostaglandin (PG) H2 can act as thromboxane (Tx) A2 receptor antagonists or agonists, PGI2 and/or PGD2 receptor agonists, or exhibit a mixture of the above activities. SQ 28,852, a new analog with a hexyloxymethyl omega side chain, is a potent inhibitor of PG synthesis. SQ 28,852 inhibited collagen and arachidonic acid (AA)-induced platelet aggregation and TxB2 and PGE2 formation, but did not block platelet aggregation induced by ADP or the TxA2 mimics, 9,11-azo PGH2, SQ 26,655, and U-46,619. It also blocked conversion of AA to TxB2, PGE2, and 6-keto PGF1 alpha by microsomal preparations of human platelets, bovine seminal vesicles, and bovine aortas, respectively, but did not inhibit the conversion of PGH2 to TxA2 by the platelet microsomal preparation. SQ 28,852 (p.o.) protected mice against the lethal effects of AA (75 mg/kg, i.v.). The I50 values for SQ 28,852, indomethacin and aspirin were 0.025, 0.05 and 15 mg/kg, respectively. Neither SQ 28,852 nor indomethacin protected mice from death caused by 9,11-azo PGH2. SQ 28,852 (0.01 to 1 mg/kg, i.v.) inhibited AA-induced bronchoconstriction in anesthetized guinea pigs for at least 60 min. As an inhibitor of AA-induced bronchoconstriction, SQ 28,852 was 16- and 45-times more potent than indomethacin at 3 and 60 min after i.v. administration, respectively. SQ 28,852 did not inhibit bronchoconstriction induced by histamine or 9,11-azo PGH2, indicating its specificity of action in vivo. SQ 28,852 is the first example of a new class of cyclooxygenase inhibitors whose structure is similar to that of the naturally occurring endoperoxide, PGH2.     

IDIOPATHIC PULMONARY HEMOSIDEROSIS

Idiopathic pulmonary hemosiderosis is a rare condition manifested by recurrent pulmonary hemorrhage of unknown cause, diffuse radiologic abnormalities, cough, hemoptysis and moderate to severe hypochromic anemia. Diagnosis can be confirmed by iron stains of the sputum or lung aspiration or by biopsy. Prolonged spontaneous remission may occur without the use of corticosteroid therapy. Studies here reported indicated that the anemia is hypochromic and microcytic anemia of blood loss and iron deficiency, in spite of the presence of large amounts of iron in the pulmonary tissue. Correction of the anemia by intensive iron therapy and transfusion is considered an important part of therapy.