Interesterification selectivity in lipase catalyzed reactions of low molecular weight triglycerides

Summary In the absence of an organic solvent, a buffer to enzyme weight ratio of 1 gives maximum selectivity to interesterification over hydrolysis in a lipase-catalyzed mixture of triacetin and tributyrin. Addition of hexane enhances interesterification as does a reversed micelle configuration.     

Platelet activating factor induces expression of early response genes c-fos and TIS-1 in human epidermoid carcinoma A-431 cells

The effect of platelet activating factor (PAF) on the induction of early response genes was investigated in A-431 cells (human epidermal carcinoma cells). PAF induced a transient expression of c-fos and TIS-1 mRNA in a time- and dose-dependent manner. As low as 10(-10) M PAF caused detectable expression of these genes with a maximum observed at 10(-7) M. In the presence of cycloheximide, increases in the gene expression were noticeable at 20 min and peaked between 30-60 min. A lack of induction with lyso-PAF, an inactive PAF metabolite, confirmed the specificity of PAF towards this expression. The cells pretreated with CV-6209, a PAF receptor antagonist, did not show any induction of these genes by PAF. It is concluded that PAF causes induction of the early response genes c-fos and TIS-1 in a structurally specific and receptor dependent manner. This finding offers a new role for PAF at the nuclear level and may have important implications in the long term effects of PAF in pathophysiological conditions.     

Evaluation of the leaf juice of some higher plants for their toxicity against soil borne pathogens

Out of the leaf juices of eighteen plant species screened, only Eupatorium cannabinum exhibited complete toxicity against Pythium debaryanum, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Shade drying of the leaves had no adverse effect, while oven drying produced an adverse effect on the fungitoxicity of the leaves of E. cannabinum. The crude leaf juice of E. cannabinum successfully inhibited damping-off (Fusarium oxysporum) infection of Pisum sativum seedlings.     

Lipid fluidity and composition of the erythrocyte membrane from healthy dogs and labrador retrievers with hereditary muscular dystrophy

Erythrocyte membranes and their liposomes were prepared from clinically normal dogs and Labrador retrievers with hereditary muscular dystrophy. The static and dynamic components of fluidity of each membrane were then assessed by steady-state fluorescence polarization techniques using limiting hindered fluorescence anisotropy and order parameter values of 1,6-diphenyl-1,3,5-hexatriene (DPH) and fluorescence anisotropy values ofdl-2-(9-anthroyl)-stearic acid anddl-12-(9-anthroyl)-stearic acid, respectively. Membrane lipids were extracted and analyzed by thin-layer chromatography and gas chromatography. The results of these studies demonstrated that the lipid fluidity of erythrocyte membranes, and their liposomes, prepared from dystrophic dogs were found to possess significantly lower static and dynamic components of fluidity than control counterparts. Analysis of the composition of membranes from dystrophic dogs revealed a higher ratio of saturated fatty acyl chain/unsaturated chains (w/w) and lower double-bond index. Alterations in the fatty acid composition such as decrease in levels of linoleic (18:2) and arachidonic (20:4) acids and increase in palmitic (16:0) and stearic (18:0) acids were also observed in the membranes of dystrophic animals. These associated fatty acyl alterations could explain, at least in part, the differences in membrane fluidity between dystrophic and control dogs.     

Role of calcium channel in postvagal potentiation of contraction as evident from the effects of Mn2+, La3+, D-600, and deoxycholate on isolated guinea pig atria-vagus nerve preparation

The role of the calcium channel in the first large contraction (postvagal potentiation, PVP) of the atria at the end of the inhibitory phase of its response (IPR) to vagal stimulation has been investigated by studying the effects of agents acting on the calcium channel (e.g., Ca2+, Mn2+, La3+, and D-600) or sarcoplasmic reticulum (SR) (e.g., deoxycholate (DOC)). IPR was potentiated by high [Ca2+]o (3-16 mM) and also by the calcium channel blockers, Mn2+ (1 microM-0.5 mM), La3+ (0.1 microM-0.5 mM), D-600 (1.0-10 microM), and DOC (1 microM-0.5 mM). PVP was also potentiated by enhanced [Ca2+]o, but the PVP ratio, which employs a correction for the simultaneous changes in the force of spontaneous contraction was inhibited. This indicated greater potentiation of contractility during spontaneous activity by Ca2+ than during PVP. Mn2+, La3+, and D-600 and even DOC in the above concentrations inhibited PVP but increased the PVP ratio. High concentrations of DOC (greater than 1 mM), which disrupt SR, strongly inhibited PVP. It is concluded that the calcium channel plays a more prominent role in spontaneous contractions than in PVP in guinea pig atria. PVP is suggested to be generated by excessive triggered release of Ca2+ from SR leading to a marked increase in [Ca2+]i. The calcium channel and the calcium trapped in the glycocalyx also play significant roles in PVP.     

Forearm skin and muscle vasoconstriction during lower body negative pressure

In view of conflicting reports of skeletal muscle and skin blood flow participation in baroreceptor-mediated reflexes, we studied the effects of graded lower body negative pressure (LBNP) on cutaneous and muscular components of forearm blood flow (FBF) in seven male subjects at 28 degrees C. FBF was measured by venous occlusion plethysmography and cutaneous flow by laser-Doppler velocimetry, the difference being the muscular flow. Mean FBF decreased by 39 and 56% from control at LBNP of 20 and 50 Torr, respectively. Skin flow decreased linearly with graded LBNP contributing 32% of the decrease of total blood flow at 20 Torr and then 50% of total decrease of blood flow at 50 Torr. Conversely, the decrease in muscle flow represented 68% of the total decrease at LBNP of 20 Torr and then 50% of the total decrease at LBNP of 50 Torr. We concluded that both skin and muscle circulations participate in sustained peripheral vasoconstriction during LBNP, with muscle flow achieving near maximum vasoconstriction by 20 Torr and skin showing a graded vasoconstriction to decreases in LBNP.     

Isolation of a hydroxyproline-secreting pigment-deficient mutant ofNostoc sp. by metronidazole selection

Summary A pigment-deficient mutant ofNostoc sp. was induced by N-methyl-N-nitro-N-nitrosoguanidine and selected in a medium containing metronidazole. It formed chains of heterocysts, grew more slowly than the control, and excreted hydroxyproline into the medium, imparting a pinkish-brown colour to the cultures.

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Aislamiento de un mutante do Nostoc sp. deficiente en pigmentos y secretor de hidroxiprolina en un medio selectivo con metronidazol

Resumen Un mutante pigmento-deficiente deNostoc sp. fue inducido mediante N-metil-N-nitro-N-nitrosoguanidina y seleccionado en un medio conteniendo metronidazol. La cepa mutante creció más lentamente que la control formando cadenas de heterocistos y excretando hidroxiprolina al medio lo cual confirió una coloración rosa-parduzca a los cultivos.

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Isolement par sélection avec le métronidazole d'un mutant de Nostoc sp. excrétant de l'hydroxyproline et déficient en pigment

Résumé Un mutant deNostoc sp. déficient en pigment a été induit par la N-méthyl-N-nitro-N-nitrosoguanidine et sélectionné dans un milieu contenant du métronidazole. Ce mutant forme des chaînes d'hétérocystes, pousse plus lentement que le contrôle, et excréte de l'hydroxyproline dans le milieu, conférant aux cultures une coloration brun rosâtre.

     

Antagonistic effects of estradiol dipropionate and progesterone on the histology of the vagina and uterus of the mouse

Administration of estradiol dipropionate (20 micrograms/day; 7 days) to ovariectomized mice caused heavy epithelial proliferation and intense cornification in the vagina and cellular as well as glandular proliferation in uterine tissues. Endometrial hypertrophy with cystlike appearance of uterine glands was seen in response to a long-term (14 days) administration of estradiol dipropionate. Daily injection of progesterone (2 mg; 7 days) to ovariectomized mice resulted in desquamating mucosa, without any trace of vaginal cornification, and the presence of dense uterine connective tissue in the stromal region with typical uterine glands. However, treatment of estradiol depropionate in combination with progesterone at 1:100 dose ratio for 7 days produced vaginal histology similar to that in proestrus and uterine histology equivalent to the ovariectomized condition. The results revealed that progesterone antagonized the estrogenic effects and also that estradiol dipropionate antagonized the effects of progesterone. The effects of the two female sex steroids (estradiol dipropionate and progesterone) in vivo appeared to be more potent in the uterus than in the vagina.     

Studies on Antifungal Properties of Essential Oil of Trachyspermum ammi (L.) Sprague

The essential oil from the fruits of Trachyspermum ammi exhibited toxicity at 800 ppm against Aspergillus flavus and A. niger, the nature of toxicity being cidal. The toxicity of the oil was not affected by autoclaving, temperature treatment and storage upto 365 days. The oil killed the test fungi within 50 seconds; withstood heavy inoculum density and was inhibitory to as many as 21 fungi at its minimum inhibitory concentration. However the seeds of Arachis hypogea whentreated with oil at 5000 ppm and stored for 12 months did not show the appearance of any fungi indicating thereby the grain protectant activity of the oil. The oil was characterized by various physico chemical properties and on chemical investigation Thymol and p-cymene were isolated as antifungal principles of the oil exhibiting toxicity against the test fungi at 1000 ppm.