Granuloma formation to Capillaria hepatica eggs. I. Descriptive definition

The course of the cellular response in the liver to nonembryonated Capillaria hepatica (Bancroft, 1893) eggs given by intravenous injection into the portal circulation of unsensitized and sensitized mice was studied qualitatively and quantitatively. A gradual infiltration of predominantly mononuclear cells occurred around the eggs in the liver, leading to the formation of distinct granulomatous lesions characterized by macrophages and lymphocytes. This was followed by an infiltration of eosinophils. Previous intraperitoneal sensitization led to an earlier and an enhanced reaction to an intravenous challenge with eggs. Specificity of the cellular response was suggested by the lack of an enhanced reaction to presensitization with eggs of a closely related species, Trichuris muris. These studies indicate that granuloma formation to C. hepatica eggs has an immunological basis and furthermore the cell composition of the granuloma would suggest that a cell-mediated component may be involved as part of the specific response.     

A variable minisatellite sequence in the chloroplast genome of Sorbus L. (Rosaceae: Maloideae).

The chloroplast genome is now known to be more variable than was once thought. Reports of RFLP (restriction fragment length polymorphism) and sequence variation, as well as variation in chloroplast microsatellites, are common. Here, data are presented on the variability of a minisatellite sequence in the chloroplast genome of Sorbus species. RFLP analysis of a PCR product comprising the region between the trnM and rbcL genes of nine Sorbus species identified seven size variants. Sequencing revealed the observed size polymorphism to be due to differences in the number of copies of an imperfect 9-bp motif. A more intensive survey of the variability of the minisatellite was undertaken in populations of Sorbus aucuparia. The potential uses of such regions in chloroplast DNA are discussed and a possible mechanism for the evolution of the minisatellite is presented.     

Deprivation and repletion of androgen in vivo modifies triacylglycerol synthesis by rat hepatocytes

Given the same quantity of fatty acid, livers from male rats esterify less fatty acid and secrete less triacylglycerol in very-low-density lipoprotein than do livers from female animals. To elucidate the role of testosterone in maintenance of this male pattern, conversion of [1-14C]oleic acid into triacylglycerol was assessed in vitro by rat hepatocytes (male) following gonadectomy and replacement with testosterone. Following castration, incorporation of fatty acid into triacylglycerol was increased. In contrast, esterification of exogenous fatty acid into phospholipid, cholesteryl esters, and diacylglycerol was unchanged. Treatment with testosterone (75 micrograms/day) reduced incorporation of exogenous fatty acid into triacylglycerol. Higher doses of testosterone (200 or 100 micrograms/day) modified the effect, such that inhibition was observed only at low oleate (0.5 mM) concentrations. At higher substrate concentrations (1.0-2.0 mM) the inhibitory effect was no longer observed. Further, a similar dose-dependent effect of testosterone was observed following in vivo treatment of castrate females with testosterone. These data support the concept of a regulatory role of testosterone in hepatic triacylglycerol synthesis. These findings also demonstrate a biphasic effect of testosterone, an effect that is dependent not only upon the dose of testosterone administered, but also on the concentration of fatty acid to which the hepatocyte is exposed in vitro.     

Effects of selective cholecystokinin antagonists L364,718 and L365,260 on food intake in rats

The selective type A and B cholecystokinin (CCK) receptor antagonists L364,718 and L365,260 were used to identify the receptor subtype that mediates the satiety effect of endogenous CCK. Male rats (n = 12–13/group), fed ground rat chow ad lib, received L364,718 (0, 1, 10, 100, or 1000 μg/kg IP) or L365,260 (0, 0.1, 1, 10, 100, 1000, or 10,000 μg/kg IP) 2 h after lights off, and food intake was measured 1.5, 3.5, and 5.5 h later. L364,718 significantly stimulated 1.5-h food intake by more than 40% at 10 μg/kg and higher doses; cumulative intake at 3.5 and 5.5 h remained elevated by about 20% at 1000 and 100 μg/kg of L364,718, respectively. In contrast, L365,260 had no significant stimulatory effect on feeding at any dose. The potency of L365,260 for antagonizing gastrin-stimulated gastric acid secretion was examined in unanesthetized rats. Male rats (n = 14), prepared with gastric and jugular vein cannulas, received doubling doses of gastrin (G-17I) (0.16–5 nmol/kg/h IV), each dose for 30 min, and gastric juice was collected for each 30-min period. G-17I stimulated gastric acid output dose dependently; the minimal effective dose was 0.16 nmol/kg/h, while maximal output (5-fold above basal) occurred at 5 nmol/kg/h. L365,260 (0, 1, 10, 100, 1000, or 10,000 μg/kg IV), administered 30 min before continuous infusion of G-17I (1.25 or 5 nmol/kg/h), significantly inhibited acid output only at 10,000 μg/kg; cumulative 60-min output was decreased by 60%. These results suggest that CCK acts at CCK-A receptors to produce satiety during the dark period in ad lib-feeding rats.     

A simple sensitive radioreceptor assay for calcium antagonist drugs

A radioreceptor assay for calcium channel antagonist drugs described here is based on the ability of these drugs to affect ³H-nitrendipine binding to calcium channels. All the known calcium channel antagonists may be assayed in this manner. The assay can detect 10–100 nM (4 – 40 ng/ml) nimodipine, 10–100 nM (3.5 – 35 ng/ml) nifedipine, 3–30 μM (1.2 – 12 μm/ml) prenylamine, 0.1 – 1.0 μM (49 – 490 ng/ml) verapamil and 3–30 μM (1.2 – 12 μg/ml) diltiazem. These values cover the range of concentrations of calcium channel antagonists that are clinically important. As the radioreceptor assay detects active metabolites as well as the parent drugs, it should prove a useful adjunct in cardiovascular therapy. The method is more reproducible, simpler and less expensive than other methods such as high pressure liquid chromatography.     

Structure and function in the excretory systems of some terrestrial prosobranch snails (Cyclophoridae)

The excretory systems of terrestrial prosobranch snails of the family Cyclophoridae, collected in Jamaica, Costa Rica and South Africa, have been examined physiologically and as regards their gross and fine structure. The process of urine formation commences in the heart, where fluid is filtered across the wall of the ventricle. Filtration through the auricular wall is believed to be negligible. The kidney, which contains three types of cell, modifies the composition of the filtrate. One type of resorptive cell, characterized by basal infoldings associated with mitochondria, takes up salts. Another type, with basal subcellular spaces, may be responsible for taking up water. The third type of cell is secretory, producing concretions of uric acid and phospholipid which are liberated into the kidney lumen when the cell degenerates.
The rate and mechanism of urine production have been investigated using injections of inulin. The filtration rate at 25°C is 0.5 μl/g/min, and in 100% R.H. the average rate of urine production is 0–39 μl/g/min.
An accessory excretory organ has been developed from the hypobranchial gland of aquatic forms. It is composed of groups of subepithelial tubular glands opening into the mantle cavity by one or a series of pores, and secreting purines, phospholipids and mucus. There is evidence that this organ becomes progressively more complex in forms occupying drier habitats.
The systems of excretion and osmoregulation in the Cyclophoridae are considered to be very similar to those in their aquatic relatives, the Viviparidae and Ampullariidae. Certainly the cyclophorids are not as well adapted to a terrestrial life as are the Pulmonata, and in many respects they may be considered "aquatic" snails living on land.