Characteristics and determinants of osmotic lysis in chromaffin granules

(1) Using isolated bovine chromaffin granules, we demonstrate that osmotic lysis is not a random process and establish the osmotic pressure dependence of osmotic lysis in chromaffin granules, the so-called osmotic fragility curve. (2) We show by measuring the release of constituents of the granule core and correlating these with changes in spectroscopic parameters (turbidity and endogenous catecholamine fluorescence), that the latter can be safely used to measure lysis. (3) Within a particular granule population, noradrenaline granules lyse at higher osmolarities than adrenaline granules, suggesting a higher core osmolarity of the noradrenaline granules. (4) The size distribution of chromaffin granules as a function of lysis was determined by the use of whole mount electron microscopy. It is shown that the mean size of chromaffin granules decreases as a function of lysis. (5) On the basis of theoretical considerations three alternative models of the sequence of osmotic lysis in chromaffin granules are proposed. The experimental results best support a model which postulates that during partial osmotic lysis, granule membranes reseal into smaller vesicles after graded release of contents. The osmotic fragility would represent several cycles of lysis and resealing and would not be a reflection of the distribution of osmotic pressures in the granule population.     

Menstruation and marital sex

This paper explores differences in sexual behavior between menstrual and nonmenstrual days, using daily report data from 85 husbands and wives for about 100 days each. Most of the men were in graduate school and the wives had a mean education of 16 years. All couples practiced contraception, but not a hormonal or rhythm method. Husband's desire for intercourse was reduced by 6%, the wife's by 19%. A sexual frustration index is arrived at by taking the % of nonintercourse days on which the respondents nevertheless reported wanting intercourse. Husbands showed a frustration index of 22% on nonmenstrual days and 36% on menstrual days. Wives demonstrated a 15% sexual frustration level when not menstruating, 19% during menstruation. The frustration reduction index (arrived at by counting the number of "want intercourse days" on which orgasm occurred without intercourse), was 17% in husbands on menstrual days, 10% on nonmenstrual days; for wives the index was 7% on menstrual days, 6% on nonmenstrual days. The authors conclude that in the highly educated group studied, intercourse and orgasm are reduced during menstruation, in association with impressively less female desire for intercourse during menstruation. The women respond to a resultant potential increase in male sexual frustration by providing the husbands an increase in noncoital orgasm on menstrual days. However, the wives do not experience an increased intercourse frustration level during menstruation and their heterosexual noncoital orgasm rate is relatively stable throughout the cycle. The different patterns of desire levels for husbands and wives may have a biological base, and the different behavior observed represent a sociological compromise.     

Hippocampal electrical activity and gamma-aminobutyrate metabolism in brain tissue following administration of homocysteine

Abstract: The concentration of γ-aminobutyrate (GABA) and the activity of glutamate decarboxylase and GABA-transaminase were measured in extracts of mouse brain before the onset and during the course of generalized seizures induced by systemic administration of homocysteine thiolactone. The results indicate that whole brain GABA metabolism is unaffected by subconvulsive and convulsive doses of homocysteine at all stages of the generalized seizure. Electroencephalographic monitoring of rat brain electrical activity via hippocampal electrode implantation allowed the course of homocysteine-induced seizures to be followed and afforded a means of quantifying such seizures.     

The effects of adrenal and gonadal steroids and K+-canrenoate on the metabolism of aldosterone by rat liver microsomes

The synthesis of polar aldosterone metabolites by rat liver microsomes at physiological concentrations of aldosterone (21.5 nM), was markedly inhibited by progesterone, testosterone, corticosterone, K+-canrenoate and estradiol-17 beta. In contrast, corticosterone and estradiol-17 beta significantly increased the synthesis of reduced aldosterone metabolites by 8- and 15-fold respectively, the majority of which were 5 alpha-reduced products of aldosterone. In experiments at higher substrate (aldosterone) concentrations (20-200 microM) the synthesis of ring A-reduced aldosterone metabolites by liver microsomes followed Michaelis-Menten kinetics with a Km[app] for aldosterone of 160 microM and Vmax[app] of 12.2 nmoles/mg protein/5 min. In these experiments progesterone, testosterone and K+-canrenoate all competitively inhibited the synthesis of reduced metabolites with inhibition constants (Ki [app]) of 70, 85 and 55 microM respectively; however, corticosterone did not. In contrast, estradiol-17 beta increased the rate of synthesis of reduced products by 40%, lowering the Km[app] to 83 microM.     

DNA replication and repair in ataxia telangiectasia cells exposed to bleomycin

A marked increase in sensitivity to bleomycin was observed in two ataxia telangiectasia (AT) lymphoblastoid cell lines compared to that in cell lines from two normal individuals. This sensitivity was obtained at two different concentrations of bleomycin. While normal cells showed a rapid recovery of ability to divide, there was no indication of such a recovery in AT cells up to 120 h after bleomycin treatment. A similar level of breakage of DNA occurred in both cell types after incubation with bleomycin. The rate of repair of these breaks was also the same. DNA synthesis was found to be more resistant to bleomycin in AT cells than in control cells. The latter data are in keeping with results previously obtained using ionizing radiation.     

Studies of a spring phytoplankton bloom in an enclosed experimental ecosystem. I. Biochemical changes in relation to the nutrient chemistry of water

A spring bloom of diatoms which occurred in large enclosed ecosystem bags at Loch Ewe, Scotland, during 1980, has been the subject of a chemical study. Changes observed in the general biochemical composition of the diatoms during the bloom are compared with the species distribution and changes in the nutrient chemistry of the bag water. The results indicate that major changes in cell biochemistry are associated with the growth, development, and decay of a diatom bloom, particularly if one or more nutrients become limiting.     

Immunoassay of muscle-specific creatine kinase with a monoclonal antibody and application to myogenesis and muscular dystrophy.

A competition e.l.i.s.a. (enzyme-linked immunosorbent assay) is described that enables direct measurement of the muscle-specific polypeptide of chick creatine kinase (M-CK) in extracts of differentiating muscle-cell cultures and in blood plasma samples, even in the presence of embryonic, or brain-type, creatine kinase. The characteristics of the assay can be considerably improved by the use of a monoclonal antibody, CK-ART, instead of rabbit antisera, and we offer an explanation for this in terms of heterogeneity of antibody affinities in polyclonal antisera. In addition to native enzyme, the assay will measure creatine kinase unfolded and inactivated by 8 M-urea treatment. During chick muscle differentiation in vitro, M-CK increased from 7.5% of the total creatine kinase at 24h to 76.0% at 143h, in good agreement with isoenzyme separation data. As a percentage of the total cell protein, M-CK increased by 156-340-fold over the same period and constituted 0.38-0.56% of the total protein in late cultures. E.l.i.s.a. measurements on 17-20-day embryonic thigh-muscle extracts, which contain almost exclusively M-CK, agree well with enzyme activity and radioimmunoassay. M-CK constituted 0.7-1.6% of the total protein in 17-19-day embryonic thigh muscle. Plasma M-CK concentrations in normal 2-8-week-old chickens were found to be in the range 0.5-0.9 micrograms/ml. Plasma concentrations of 32-56 micrograms/ml were found in 8-week-old dystrophic chickens by both e.l.i.s.a. and enzyme-activity measurements. The results suggest that inactive or unfolded forms of M-CK do not normally exist, in any significant amounts, in cell and tissue extracts or in freshly prepared samples of plasma.     

Immunohistochemistry of tonin in rat submandibular gland during development, lactation and secretion

Tonin is a serine protease found in high concentrations in the submandibular gland (SMG) of the adult rat where it has been localized by immunohistochemistry in the granular ducts. The present study examined the development of tonin in the SMG, the effect of lactation and of stimulation of tonin release, using the peroxidase-antiperoxidase technique and antitonin. Tonin-like immunoreactivity first appeared in the primitive striated duct of the SMG on day 19 foetal and increased in intensity as the ducts developed into granular ducts. Reaction product in granules was seen on day 17 postpartum. Its localization within granules was established by immunochemistry of Sepharose beads to which had been coupled the contents of granules isolated from adult rats. The granular ducts of female rats, which are less developed than in the male, showed a marked increase in tonin-immunoreactivity during lactation. Stimulation of tonin secretion by isoprenaline caused massive discharge of tonin-like immunoreactivity into the lumen of the granular ducts during in vitro incubation. However, within one hour complete regranulation was apparent. The secretion was prevented by propranolol. The results indicate that tonin or a tonin-like substance appears in the rat submandibular gland late in gestation in ducts that presumably develop into granular ducts where it is found in abundance in granules in the adult, that the amount in females is increased during lactation, and that most of the granules are discharged during stimulation, only to be rapidly replaced.     

Chicken lens delta-crystallin gene expression and methylation in several non-lens tissues.

RNA sequences coding for the most abundant chicken lens proteins, delta-crystallin, were detected at very low levels in day old post hatch chick lung, heart, kidney and liver, and in 6 day embryo headless bodies. The pattern of cytosine methylation within the CCGG sequences of the delta-crystallin genes was also examined and shown to vary in several non-lens tissues, from several stages of development. Embryonic neural retina, which expresses a higher level of delta-crystallin RNA than the above tissues, is no less methylated in the sites studied than the tissues which have no association with the eye, and is actually more heavily methylated than the kidney. Thus no obvious correlation was found between undermethylation and gene expression.