Incorporation of 18O2 into brain serotonin in vivo as a procedure for estimating turnover: a feasibility study in animals.

Serotonin (5HT) containing ¹⁸0 instead of ¹⁶0 was found in brain after exposing rats to an atmosphere of ¹⁸0₂. The ¹⁸0 incorporation appeared linear with time and 22% of the 5HT in striatum contained ¹⁸0 after one hour of exposure. ¹⁸0 entered 5HT by enzymatic reaction rather than by isotope exchange as treatment with p-chlorophenylalanine, to block tryptophan hydroxylase, prevented incorporation, while more ¹⁸0-5HT than normal was found in brain after treatment with pargyline, to block monoamine oxidase. Our studies suggest that the incorporation of ¹⁸0₂ into brain 5HT might be a feasible approach for evaluating 5HT turnover in animals and with some modification might be applied in man.     

Adaptation to chronic hypobaric hypoxia and sexual hormones

The role of the gonads and their hormones on body weight was studied in rats of both sexes submitted to chronic hypoxia and their controls at sea level atmospheric pressure. Intact rats were exposed to either 4 700 or 6 000 m simulated altitude in a hypopressure chamber. Castrated rats and castrated rats daily injected with either 0.5 mg of testosterone or 20 microgram of estradiol or the vehicle, were exposed to the higher altitude. The rat weight was recorded for a period of at least eight weeks. All groups of hypoxic male animals increased their weight significantly less than the controls at sea level. Also in castrated females and in castrated injected with testosterone or the vehicle the same pattern of weight curves was observed. On the contrary, groups of intact females and castrated females injected with estradiol did not show significant differences between hypoxic and control animals. Only in a group of smaller intact females (50-80 g) the body weight increase was significantly diminished by exposure to either 4 700 or 6 000 m simulated altitude.     

Studies on the adenosine 3′,5′-monophosphate-dependent protein kinase of Blastocladiella emersonii

Using a combination of Chromatographic and sucrose density gradient techniques under carefully controlled conditions of pH and protease inhibitors, we demonstrate that there is only one form of adenosine 3′,5′-monophosphate-dependent protein kinase in the cytosol fraction of the Blastocladiella emersonii zoospore. If any of these conditions are omitted during extract preparation, one obtains what are apparently multiple forms of the enzyme, which are in reality artifacts due to extensive endogenous proteolytic activity. This endogenous protease is stimulated by alkaline pH and inhibited by antipain. The zoospore protein kinase is similar to type II protein kinase from mammalian cells in several aspects including Chromatographic behavior on DEAE-cellulose column, conditions for subunit dissociation and reassociation, as well as the molecular weight value of the regulatory subunit.     

Periodontal disease in the prehistoric Ipiutak and Tigara skeletal remains from Point Hope,Alaska

Two large groups of prehistoric Eskimo skeletons from Point Hope, Alaska, were evaluated for dental wear and several measures of periodontal disease. Occlusal attrition was found to increase steadily with increasing age. Crown height decreased proportionately. Assessing periodontal disease by inspecting apparent alveolar recession was judged ineffective due to possible supereruption. Infrabony pockets, the result of severe localized periodontal disease indicated that in Ipiutak people between the ages of 25 and 30, and Tigara people between 35 and 40, more dental sites were affected by periodontal disease than were not. This suggests a cultural, genetic, or dietary difference between the two groups. Male/female differences were slight in all parameters studied.     

Sulfur-containing cyclic ketimines and imino acids. A novel family of endogenous products in the search for a role.

Aminoethylcysteine, lanthionine, cystathionine and cystine are mono-deaminated either by L-amino-acid oxidase or by a transaminase exhibiting the properties described for glutamine transaminase. The deaminated products cyclize producing the respective ketimines. Authentic samples of each ketimine were prepared by reacting the appropriate aminothiol compound with bromopyruvate, except cystine ketimine which required the interaction of thiopyruvate with cystine sulfoxide. Reduction of the first three mentioned ketimines with NaBH4 yields the respective derivatives with the saturated rings of thiomorpholine and hexahydrothiazepine. The same reduction is carried out enzymically by a reductase extracted from mammalian tissues. Properties of the members of this family of compounds are described. Gas chromatography followed by mass spectrometry permits the identification of most of these products. HPLC is very useful for the determination of the ketimines by taking advantage of specific absorbance at 380 nm obtained by prior derivatization with phenylisothiocyanate. Adaptation of these and other analytical procedures to biological samples disclosed the presence of most of these compounds in bovine brain and in human urine. By using [35S]lanthionine ketimine as a representative member of the ketimine group, the specific, high-affinity, saturable and reversible binding to bovine brain membranes has been demonstrated. The binding is removed by aminoethylcysteine ketimine and by cystathionine ketimine indicating the occurrence in bovine brain of a common binding site for ketimines. The reduced ketimines are totally ineffective in competing with [35S]lanthionine ketimine. Alltogether these findings are highly indicative for the existence in mammals of a novel class of endogenous sulfur-containing cyclic products provided with a possible neurochemical function to be investigated further.     

The effect of feeding on plasma immunoreactive ACTH and beta-endorphin levels in newborn infant.

In order to clarify whether an interaction between endogenous opioids and feeding occurs at birth, we studied Beta-endorphin (beta-EP) and ACTH plasma levels in response to a feed of 10% glucose, or formula, in 120 healthy full-term infants. Neither postprandial beta-EP nor ACTH increases were found at the 24th hour or on the fourth day of life. beta-EP physiology in newborn infants seems to be different from adults.     

Effects of progesterone and estradiol on the proliferation of phytohemagglutinin-stimulated human lymphocytes

In this paper we report on a study to elucidate whether the response of human lymphocytes to mitogenic stimulation was modified by physiological changes which occur during the menstrual cycle. Experiments with untreated cultures showed intra-individual variation to mitogen stimulation in female lymphocyte cultures, but a significant correlation between the menstrual cycle and the proliferation kinetics of lymphocytes was not found. Consequently, we performed experiments in which two of the hormones that regulate the menstrual cycle in women, estradiol and progesterone, were added to cultured human lymphocytes obtained from both men and women. The results indicate that both hormones at physiological concentrations have the capacity to modify the proliferation of PHA-stimulated human lymphocytes. Therefore, both hormones could play a role in the induction of the intra-individual variation observed in the untreated female cultures. However, in vivo other factors could also modify the proliferation kinetics of human lymphocytes preventing the demonstration of the effects of a single factor, such as the hormonal changes occurring during the menstrual cycle.     

Gastrulation in Drosophila: the formation of the ventral furrow and posterior midgut invaginations

The ventral furrow and posterior midgut invaginations bring mesodermal and endodermal precursor cells into the interior of the Drosophila embryo during gastrulation. Both invaginations proceed through a similar sequence of rapid cell shape changes, which include apical flattening, constriction of the apical diameter, cell elongation and subsequent shortening. Based on the time course of apical constriction in the ventral furrow and posterior midgut, we identify two phases in this process: first, a slow stochastic phase in which some individual cells begin to constrict and, second, a rapid phase in which the remaining unconstricted cells constrict. Mutations in the concertina or folded gastrulation genes appear to block the transition to the second phase in both the ventral furrow and the posterior midgut invaginations.