Endogenous phosphorylation of retinal photoreceptor outer segment proteins by calcium phospholipid-dependent protein kinase

A calcium phospholipid-dependent protein kinase (C-kinase) activity was detected in the soluble fraction of rod outer segments (ROS) of the bovine retina. The enzyme required calcium, phosphatidylserine (PS) and diacylglycerol for maximal activity. In the presence of calcium and PS, C-kinase endogenously phosphorylated proteins with molecular weights of 95,000, 91,000, 31,000, 21,000, 19,000, 18,000, 16,000, 14,000 and 11,000. Addition of diolein in the reaction mixture further enhanced the endogenous phosphorylation of these proteins. Retinal was found to inhibit the phosphorylation of endogenous proteins by C-kinase in a concentration dependent manner. Half-maximal inhibition of enzyme activity was obtained at a retinal concentration of about 12μM. These results suggest that calcium, phospholipids and the C-kinase enzyme may play an important role in the functional regulation of rod photoreceptors and, with retinal, perhaps in the visual process as well.     

Nitrate reductase,nitrite reductase activities and leaf diffusive resistance in wheat under water deficit

The flag and second leaves of wheat showed physiological and biochemical differences in the normal and water stressed plants. Although the flag leaf had lower enzyme activities in the control plants, in stressed plants it could continue nitrate assimilation better than the second and other leaves. The flag leaf also exhibited a higher tendency to resume normal metabolic activity after the release of stress as is indicated by higher NRA, NiRa, lower r_ad and r_ab.     

Purification and properties of indole 2,3-dioxygenase from maize leaves

An indole 2,3-dioxygenase was purified ca 38-fold from maize leaves. The enzyme had an MW of about 98000, an optimum pH of 5.0 and the energy of activation was 9.1 kcal/mol. The K_max for indole was 1.4 × 10^?4 M. The enzyme was inhibited by diethyldithiocarbamate, salicylaldoxime and sodium dithionite. The inhibition by diethyldithiocarbamate was specifically reversed by Cu²⁺. The dialysed enzyme was stimulated by Cu²⁺. Four atoms of oxygen were utilized in the disappearance of 1 mole of indole. Inhibition of the enzyme by -SH compounds and -SH group inhibitors, and their partial removal by Cu²⁺ only, suggested the involvement of -SH groups in binding of Cu²⁺ at the catalytic site.     

Studies on the C-24 configurations of Δ7-sterols in theseeds of Cucurbita maxima

Uncertainties surrounding the structures of the Δ⁷-sterols in the seeds of Cucurbita maxima have been resolved. Seven components were found by TLC, GLC, HPLC, mass spectrometry and ¹H NMR. They were 24β-ethyl-5α-cholesta-7,22,25(27)-trien-3β-ol, 24β-ethyl-5α-cholesta-7,25(27)-dien-3gb-ol, avenasterol, spinasterol, 24-dihydrospinasterol, 24ζ-methyllathosterol and 25(27)-dehydrofungisterol. The ¹H NMR spectra indicated that the sterols with an ethyl substituent at C-24 occurred in the absence of their C-24 epimers. This seems to be the first instance of the detection of 25(27)-dehydrofungisterol in a higher plant.     

Kinetics of reabsorption of nutrients in renal brush border membrane vesicles from rats with experimental ascending pyelonephritis

The uptake of nutrients was investigated in the renal cortical brush border membrane (BBM) vesicles at different stages of ascending pyelonephritis. There was significant difference (p less than 0.05) in the uptake of D-glucose, L-alanine, L-aspartate, L-lysine and L-proline 3 days postinfection and onwards in both right unobstructed and left obstructed experimental kidneys as compared to the sham operated control. The uptake of D-glucose, L-lysine and L-proline was found to be significantly decreased (p less than 0.05) during the course of infection. While uptake of L-alanine and L-aspartate increased (p less than 0.05) in early stages and decreased (p less than 0.05) in later stages of infection. The differential effect was attributed to the compensatory measure and different kinds of transport systems for different types of amino acids.     

The pentylenetetrazol model of anxiety detects withdrawal from diazepam in rats

This experiment tested whether benzodiazepine withdrawal could be detected in an animal model of anxiety. Rats were trained in operant chambers using food reward to press one lever after pentylenetetrazol (PTZ), 20 mg/kg, injection and the other lever after saline injection. Previously, the PTZ cue has been shown to be simulated by anxiogenic drugs and blocked by anxiolytic drugs. After rats reliably performed this discrimination, they were injected with diazepam, 20 mg/kg, from 1 to 4 times a day for six days. For one group of subjects, on the third, fourth and sixth days, they were also injected with 40 mg/kg of RO 15-1788, a benzodiazepine receptor antagonist, and tested for lever selection: 50–80% of the subjects selected the PTZ lever; these results are in contrast to those obtained prior to chronic diazepam treatment in which RO 15-1788 did not generalize to PTZ. A second group of subjects was also injected for six days with diazepam and then allowed to withdraw spontaneously for eight days: PTZ lever selection over this period varied from 20 to 60% of rats. These data indicate that animals trained to discriminate a PTZ cue: 1) generalize the benzodiazepine withdrawal state to the PTZ cue, and 2) discriminate the withdrawal state for long periods of time, agreeing with clinical observations of long-lasting anxiety signs during benzodiazepine withdrawal.     

Discriminative stimulus properties of L-phenylisopropyl adenosine: blockade by caffeine and generalization to 2-chloroadenosine

Recent neurochemical data on the effects of activation and blockade of adenosine A1 receptors has suggested a direct role of adenosine in neurotransmission. The present research used a drug discrimination procedure to test the hypotheses that A1 adenosine receptor activation could serve as a discriminative stimulus and that caffeine, a drug believed to be an A1 receptor antagonist, could block the adenosine discrimination. Food-deprived rats were trained to press one of two levers on an FR 10 schedule of food-pellet delivery. Responses on one lever were reinforced following i.p. injection of N6 - (L-phenylisopropyl) adenosine (L-PIA); responses on the other lever were reinforced following i.p. injection of saline. L-PIA training dose was increased from 0.064 to 0.08 mg/kg L-PIA in the course of the study. Subjects required an average of 91 sessions to acquire this discrimination. Stimulus control by L-PIA was dose-dependent, with the ED-50 being approximately 0.03 mg/kg. 2-Chloroadenosine (2CA) generalized to L-PIA with a tenth the potency. Caffeine blocked L-PIA-induced lever selection. These results indicate that 1) rats can be trained to discriminate L-PIA from saline in a two-lever food-reinforced task and 2) the discriminative stimuli produced by L-PIA are based on its agonistic action at the adenosine A1 receptor.     

Clinical and experimental keratitis caused by the Colletotrichum state of Glomerella cingulata and Acrophialophora fusispora

Two cases of mycotic keratitis caused by the Colletotrichum state of Glomerella cingulata and Acrophialophora fusispora are reported for the first time. Both the isolates produced experimental corneal lesions in rabbit eyes but A. fusispora was more pathogenic. The experimental infection was more severe, with both the fungi, in rabbits pretreated with cortisone as compared with untreated animals. In vitro A. fusispora was most sensitive to miconazole and tolciclate followed by clotrimazole, amphotericin B and lactones while clotrimazole exerted maximum inhibitory effect on Colletotrichum followed by miconazole, lactones, amphotericin B and arnebins. Arnebins and tolciclate were inactive respectively against A. fusispora and Colletotrichum. Of the 3 drugs tested in vivo, against A. fusispora keratitis in rabbit, amphotericin B showed better results than tolciclate and miconazole.     

Oxo fatty acid esters from Cryptocoryne spiralis rhizomes

Two new compounds, isolated from the rhizomes of Cryptocoryne spiralis, have been characterized as ethyl 14-oxotetracosanoate and 15-oxoeicosanyl 14-oxoheptadecanoate by spectral data and chemical studies. Hentriacontane and sitosterol have also been isolated and identified.     

BCG-induced susceptibility of mice to challenge with Pseudomonas aeruginosa

Mice infected with Mycobacterium bovis, BCG, were shown to be highly susceptible to subsequent challenge with Pseudomonas aeruginosa. The susceptibility was characterized by the enhanced mortality and shortened survival after challenge with P. aeruginosa. BCG-treated mice did not show any enhanced susceptibility to challenge with Gram-positive bacteria such as Staphylococcus aureus or Listeria monocytogenes. BCG-treated mice eliminated P. aeruginosa from their organs in a pattern similar to that in untreated mice. There was no significant difference in the bactericidal activities of polymorphonuclear cells and macrophages between BCG-treated and untreated mice. An equal amount of endotoxin was detected by the Limulus lysate assay in the blood of both BCG-treated and untreated mice after challenge with P. aeruginosa. The enhanced susceptibility induced by BCG pretreatment could be decreased when the mice were rendered LPS-tolerant by injections of small amounts of LPS. These results suggest that BCG-induced susceptibility to P. aeruginosa can be ascribed to an enhanced susceptibility to the lethal effect of LPS produced by challenge bacteria, and not to the impairment of the ability to eliminate infected bacteria.