Gastric cytoprotection by intracisternal interleukin-1 beta in the rat

The effects of intracisternal (ic) injection of recombinant interleukin-1 beta (IL-1) on absolute ethanol-induced gastric necrotic lesions were studied in conscious rats. IL-1 given ic inhibited ethanol-induced gastric lesions. The cytoprotective effect was dose dependent (ED175 ng/rat), long lasting with a maximal action when given 1-3 h prior to ethanol, blocked by ic injection of a IL-1 receptor antagonist protein (IRAP), and by intraperitoneal injection of indomethacin. IL-1, injected ic, was detected in the peripheral blood. However, IL-1 serum levels were lower after IL-1 injection ic than after ip at a dose giving equal gastric protection. These data show that ic IL-1 induces long lasting gastric protection mediated by interaction with IL-1 receptors and prostaglandin pathways at central and/or peripheral sites that remain to be localized.     

In vitro and in vivo growth and casein gene expression of mouse mammary tumor epithelial cells in response to hormones

Cells from autochthonous mouse mammary carcinomas which display estrogen-independent growth _vivo were studied for their hormonal responses in primary culture. A culture system employing insulin-supplemented, serum-free medium and basement membrane Matrigel as a substratum was used to cultivate tumor cells. The cells did not exhibit in vitro estrogenor prolactin-dependent growth. Primary tumors still displayed a constitutional expression of α-, β-, and γ-casein mRNAs. These messages were dramatically reduced during the culture period. However, seven to eightfold increases in α- and β-casein mRNAs were inducible in the 5-day cultures by treatment with prolactin and hydrocortisone. If the hormones were present through a 2-week culture period, the levels of α-, β-, and γ-casein mRNAs in the cells were maintained and displayed in a time-dependent increase with a peak at 10–14 days. The accumulation of β-casein mRNA in vitro did not require DNA synthesis. Administration of prolactin directly into the growing tumors in vivo could also enhance β-casein mRNA levels in the tumor cells. Morphological studies of the cells cultured in the presence of prolactin and hydrocortisone did not reveal visible changes compared with those without hormonal treatment. Transplantation of tumor cells cultured in the presence or absence of hormones resulted in the development of tumors in mice at approximately the same time. The current studies suggest that the autochthonous mammary tumor cells, independent of estrogen for cell growth, were still inducible for casein gene expression in vitro and in vivo by appropriate hormones. The induction and maintenance of casein messages by a single hormonal treatment did not appear to correlate with morphology and DNA synthesis of cells in vitro or with tumor-producing capacities in vivo.     

Comparison of the folding of 2-Keto-3-deoxy-6-phosphogluconate aldolase,triosephosphate isomerase and pyruvate kinase: Implications in molecular evolution

The 8-fold α/β barrel conformation of 2-keto-3-deoxy-6-phosphogluconate aldolase has been compared to that of triosephosphate isomerase and the A-domain of pyruvate kinase. There are eight supersecondary structure units (α/β) in each of these proteins, and the comparisons were carried out in orientations corresponding to each of the possible congruences, i.e. first to first, first to second,… of the supersecondary structure units. The comparison of the C_α structure of the main chain folding of the three enzymes indicated about 150 equivalences with rootmean-square differences of about 3.1 Å, with no orientational preference, including the aldolase with itself. In addition, there is no sequence homology between the aldolase and the isomerase, and no indication of gene duplication in the former. The lack of orientational preference among the three enzymes suggests convergence to a fold of exceptional stability. However, all three enzymes activate a CH bond adjacent to a carbonyl, and their active sites correspond to the f strand, F helix region of the α/β barrel, thus contradicting the foregoing and suggesting divergent evolution from a common precursor. Other and similar arguments are also presented for and against convergent evolution of these three strikingly similar enzymes.     

Selective high-performance liquid chromatographic assays for hydralazine and its metabolites in plasma of man

Selective high-performance liquid chromatographic assays for hydralazine (I), hydralazine pyruvic acid hydrazone (II) and the acetylation metabolites, namely s-triazolo[3,4-a]-phthalazine (V) and 3-hydroxymethyl (VI) and 3-methyl-s-triazolo[3,4-a]phthalazine (VII) in human plasma were developed. Utilizing the fluorescence of these compounds or their derivatives the limits of detection could be extended down to 5 nmole/l (1 ng/ml) for I, 1 nmole/l (0.2 ng/ml) for II and 0.5 nmole/l (0.1 ng/ml) for V–VII. The intra-assay coefficients of variation for the assays ranged from 2 to 7% over the concentration range 5.0 to 0.05 μmole/l and the inter-assay variability in the slope of the standard curves ranged from 4 to 8%. An improved method for measuring the sum of I plus all its hydrazones (apparent I) was also developed. On addition of I to fresh plasma at 37°, half the added I was converted to II within 15 min and there was no detectable level of I, 2 h after the addition. The plasma level—time course of I, and its metabolites in a healthy volunteer (slow acetylator) following separate oral and intravenous administrations of I indicated that I contributed only a small fraction (4.3 and 4.7% respectively) to the area under the plasma level—time curve of apparent hydralazine.     

The α-keto acids of branched-chain amino acids: Simplified derivatization for physiological samples and complete separation as quinoxalinols by packed column gas chromatography

By use of a relatively new mixed stationary phase, complete separation of the branched-chain α-keto acids as O-trimethylsilyl-quinoxalinol derivatives is achieved within 10 min by packed column gas chromatography. Precise quantification of less than 5 nmol of α-keto acids in biological samples is possible. In small aqueous samples the α-keto acids are directly derivatized without prior purification. Plasma need only be deproteinized by perchlorate and neutralized before derivatization. Average relative precision for determination of the three main branched-chain α-keto acids is ± 5.8%.     

The cole-moore effect in nodal membrane of the frogRana ridibunda: Evidence for fast and slow potassium channels

Summary The K conductance (g _K) kinetics were studied in voltage-clamped frog nodes (Rana ridibunda) in double-pulse experiments. The Cole-Moore translation forg _K–t curves associated with different initial potentials (E) was only observed with a small percentage of fibers. The absence of the translation was found to be caused by the involvement of an additional, slow,g _K component. This component cannot be attributed to a multiple-state performance of the K channel. It can only be accounted for by a separate, slow K channel, the fast channel being the same as then ⁴ K channel inR. pipiens.The slow K channel is characterized by weaker sensitivity to TEA, smaller density, weaker potential (E) dependence, and somewhat more negativeE range of activation than the fast K channel. According to characteristics of the slow K system, three types of fibers were found. In Type I fibers (most numerous) the slow K channel behaves as ann ⁴ HH channel. In Type II fibers (the second largest group found) the slow K channel obeys the HH kinetics within a certainE range only; beyond this range the exponential decline of the slowg _K component is preceded by anE-dependent delay, its kinetics after the delay being the same as those in Type I fibers. In Type III fibers (rare) the slow K channel is lacking, and it is only in these fibers that the Cole-Moore translation of the measuredg _K–t curves can be observed directly.The physiological role of the fast and slow K channel in amphibian nerves is briefly discussed.     

The identification of an epoxy-hydroxy acid as a product from the incubation of arachidonic acid with washed blood platelets

An epoxy-hydroxy compound, 10-hydroxy-11,12-epoxy-eicosa-5,8,14-trienoic acid, has been identified as a product on incubation of arachidonic acid with washed blood platelets from human, horse, cat, dog and rabbit. Gas chromatographic - mass spectrometric (GC-MS) evidence of structure is discussed.     

Homing behavior of pigeons not disturbed by application of an olfactory stimulus

Summary In a second attempt to repeat recently published experiments that appear to support an hypothesis that olfactory cues play an important role in pigeon navigation, we have conducted 15 experiments in which-pinene in vaseline was applied to the birds' beak and nostrils prior to release, a procedure reported by Benvenutiet al. (1973) to cause a decrement in homing performance. Our results show no consistent difference between the experimental and control birds in any of the three parameters (initial orientation, rapidity of orientation, homing speed) measured by Benvenutiet al. We thank our colleagues Timothy Larkin, Marilyn Yodlowski, and Lindsay Goodloe for their help in conducting the releases. This research was supported by Grant BMS 72-02198-AO2 from the National Science Foundation.