Retention of topical liposomal formulations on the cornea

Summary The ability of liposomes composed of different kinds of phospholipid materials to adhere to the surface of the cornea was studied in the rabbit. The liposomes were labelled with tracer amounts of an I¹²⁵-labelled phosphatidylethanolamine derivative and were instilled in 10 l drops onto the cornea. The retention of radioactivity was monitored. The results show that liposomes containing positively charged phospholipids are better retained than an albumin control. Thus, it may be possible to develop a drug delivery, liposome system which would permit long-term sustained release of ophthalmic drugs onto the cornea.     

Hypothalamic histamine modulates adaptive behavior of rats at high environmental temperature

Summary Histamine content in the rat hypothalamus was lower at 4°C and higher at 31°C compared to that at 21°C. Pretreatment with -fluoromethylhistidine, a suicide inhibitor of histidine decarboxylase, attenuated both the increased level of hypothalamic histamine and rat adaptive behavior at 31°C. Increase of histamine content in the hypothalamus appears to be an important factor contributing to rat adaptive behavior to high environmental temperature.     

Effects of a new cholecystokinin antagonist (GE 410) on the smooth muscle of the guinea pig ileum

Summary Suc-Tyr-(SE)-Met-Gly-Trp-Met-Asp--phenethylamide (GE 410) competitively antagonized the contractions of smooth muscle strips from guinea pig ileum (pA₂=7.6, n=0.95) induced by cholecystokinin-octapeptide (CCK8). GE 410 inhibited the electrically-induced cholinergically mediated contractile responses and the [³H]ACh release in the ileum, as well as the CCK-stimulated electrical contractile responses and the [³H]ACh release in the cholinergic nerve terminals. The results suggest the existence of CCK-receptors not only in the smooth muscles but also on the neurons.     

Gigantecin: A novel antimitotic and cytotoxic acetogenin,with nonadjacent tetrahydrofuran rings,fromGoniothalamus giganteus (Annonaceae)

Summary Gigantecin (I), a novel tetrahydroxy-di-tetrahydrofuran fatty acid -lactone (acetogenin), was isolated from an ethanolic extract of the stem bark ofGoniothalamus giganteus Hook. f., Thomas (Annonaceae), by means of activity-directed fractionation (brine shrimp lethality test). This new compound is extremely cytotoxic to human tumor cells, inhibits crown gall tumors on potato discs, and is active in an assay designed to detect antimitotic agents (9 ASK).     

Evaluations of the beta probability integral by bayes and price

Summary The contribution of Bayes to statistical inference has been much discussed, whereas his evaluations of the beta probability integral have received little attention, and Price's improvements of these results have never been analysed in detail. It is the purpose of the present paper to redress this state of affairs and to show that the Bayes-Price approximation to the two-sided beta probability integral is considerably better than the normal approximation, which became popular under the influence of Laplace, although it had been stated by Price.The Bayes-Price results are obtained by approximating the skew beta density by a symmetric beta density times a factor tending to unity for n , the two functions having the same maximum and the same points of inflection. Since the symmetric beta density converges to the normal density, all the results of Laplace based on the normal distribution can be obtained as simple limits of the results of Bayes and Price. This fact was not observed either by Laplace or by Todhunter.     

Exogenous fibronectin modifies the aggregation of collagen-stimulated human platelets

Summary Fibronectins (FN) are adhesive glycoproteins whose role in platelet aggregation is unclear. Addition of 3, 6 and 12 g/ml of human plasma FN in vitro to isolated human platelets, which had been freed from plasma FN by gel filtration and subsequently stimulated with collagen, inhibited the last stage of platelet aggregation. With 3 and 6g/ml of FN a shortening of the lag-time was also observed. These data showed that FN may play a role in platelet-collagen interaction as well as in platelet-platelet interaction.     

Nitric oxide-related pancreatic endocrine responses to hyperglycaemia in the conscious calf

Mean plasma insulin concentration was reduced and mean plasma glucose concentration increased following the administration of N-nitro-L-arginine methyl ester (L-NAME; 100 mol kg^–1 i.a.) in conscious calves given continuous infusions of exogenous glucose (30–60 mol min^–1 kg^–1 i.v.). It is concluded that the rise in plasma insulin concentration which occurs in these animals in response to glucose is mediated, at least in part, by a nitric oxide-related factor (NOx).     

Variability of sterol utilization in stored-products insects

A comparison of sterol utilization by 3 stored-products insects revealed very different capabilities. The fluor beetle,Tribolium castaneum dealkylates and converts dietary sitosterol to about equal amounts of cholesterol (43.7%) and 7-dehydrocholeterol (39.8%), whereas another flour beetle,Tenebrio molitor, produces considerably less 7-dehydrocholesterol (16.8%) and relatively more cholesterol (66.7%) from sitosterol. The lepidopteran,Plodia interpunctella, utilized dietary sterol very similar to plant-feeding lepidoptera, producing primarily cholesterol (86.5%) from sitosterol.     

A novel mechanism for jumping in the indian ant<Emphasis Type="Italic">Harpegnathos saltator</Emphasis> (Jerdon) (Formicidae,Ponerinae)

The Indian antHarpegnathos saltator may be unique among insects in using its jumping capacity not only as an escape mechanism but also as a normal means of locomotion, and for catching its prey in flight. High-speed cinematography used to analyse the various phases of the jump suggests thatHarpegnathos employs a novel jumping mechanism to mediate these behaviours: namely the synchronous activation of its middle and hindlegs. Electrophysiological recordings from muscles or nerves in pairs of middle and hindlegs show remarkably synchronous activity during fictive jumping, supporting the synchronous activation hypothesis.Harpegnathos is not the only ant to jump, and a cladistic analysis suggests that jumping behaviour evolved independently three times during ant evolutionary history.