Effects of methylphenidate and d-amphetamine on timing in the rat

Rats were trained to press a lever for food pellets provided according to a fixed interval 60-sec schedule of reinforcement. Probe trials (peak trials) assessed responding over two-min periods with no pellet delivered. The low rates of responding found early and late in probe trials were increased by methylphenidate and 1.0 mg/kg d-amphetamine (rate-dependent effect). Further, the mean time of responding (peak time) was shortened for both drugs (timing effect).     

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

Effects of Ethanol, Chlordiazepoxide, and MK-801 on Performance in the Elevated-Plus Maze and on Locomotor Activity

The effects of ethanol, chlordiazepoxide, and MK-801 on performance in the elevated-plus maze and on activity measured in a circular activity monitor were compared in Sprague-Dawley rats to determine whether these effects of ethanol could be explained by its action on either GABA_A or NMDA receptors. Both ethanol and chlordiarepoxide produced an increase in the time spent in the open arms of the elevated-plus maze and in the ratio of open arm to total arm entries, indicative of an anxiolytic action of these drugs. MK-801 did not alter either the time spent in the open arms or the ratio of open to total arm entries. Chlordiazepoxide and MK-801 produced an increase in total arm entries that suggested that these compounds were increasing locomotor activity. Ethanol also increased total arm entries, but the effect was not statistically reliable. Following habituation to an activity monitor, neither ethanol nor chlordiazepoxide increased activity in this task, whereas MK-801 produced a robust increase in locomotion. Additionally, neither ethanol nor chlordiazepoxide blocked the MK-801-induced locomotor stimulation. The latter finding suggests that the effects of ethanol on GABAA receptors was not Mocking an increased activity level produced by its antagonism of NMDA. Additionally, these results indicate that the anxiolytic and locomotor action of ethanol in rats parallel the effects of a benzodiazepine and not those of an NMDA antagonist. Finally, these results suggest that the consequence of ethanol's antagonism of NMDA receptor function is more restricted than that produced by MK-801.     

Decreased mucosal interleukin-4 (IL-4) production in gut inflammation.

AIMS--To determine the prevalence of cells secreting interleukin-4 (IL-4) in the gut mucosa of children with chronic inflammatory bowel disease. METHODS--Mononuclear cells were isolated from intestinal biopsy specimens from control children (n = 10) and children with active inflammatory bowel disease (Crohn's disease n = 15, ulcerative colitis n = 9, indeterminate colitis n = 3). Spontaneous IL-4 production was then measured by SPOT-enzyme linked immunosorbant assay (ELISA) using a pair of non-competing anti-IL-4 monoclonal antibodies. The percentage of T cells in the isolated cells were also determined and the prevalence of IL-4 secreting cells calculated per 10,000 T cells. RESULTS--In control children the mean number of IL-4 secreting cells was 15.1 per 10,000 T cells. In Crohn's disease and ulcerative colitis the means were 5.3 and 5.2, respectively. In two children with indeterminate colitis numbers were also low. There was no difference in the percentage of T cells in the cell preparations isolated from each patient group. The reduction of IL-4 secreting cells in patients with Crohn's disease was not caused by steroids. CONCLUSIONS--In idiopathic inflammatory bowel disease IL-4 secreting cells are reduced in diseased mucosa.     

Topography of basal glucose utilization in the hippocampus determined with [1-14C]glucose and [6-14C]glucose

The activity of the pentose phosphate shunt was assessed under basal conditions in subregions of the hippocampus by measuring the uptake and retention of [1-14C]glucose and [6-14C]glucose and their 14C-labelled metabolites. The relative and absolute retention of carbon-14 from each of the two compounds was nearly identical in all regions examined. For each compound, the highest accumulation of 14C occurred in the granule cell layer of the dentate gyrus and in the pyramidal cell layer. Relatively high retention of radioactivity was also found in the molecular layer of dentate gyrus and in the stratum lacunosum-molecular. The stratum radiatum and stratum oriens contained the lowest levels of radioactivity among hippocampal regions. The equal retention of radioactivity from [1-14C]glucose and [6-14C]glucose implies that pentose phosphate shunt activity is very low throughout the hippocampus under the conditions of this study. The uptake and retention of radioactivity was evaluated in different hippocampal regions 10 or 30 min following intravenous injection of [1-14C]glucose. Although there was significantly more radioactivity at 30 min than at 10 min, the same topographic pattern of radioactivity within the hippocampus was observed in rats after both survival periods, indicating that an equal fraction of the [1-14C]glucose utilized in different hippocampal regions is oxidized to 14CO2 under these conditions. Most regions of high glucose utilization in the hippocampus determined with [1-14C]glucose and [6-14C]glucose correspond to regions of intense histochemical staining for cytochrome oxidase reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)     

Virus-like particles occurring in cultures of stable pig kidney cell lines

Summary Virus-like particles resembling those seen in baby hamster kidney (BHK-21) cell cultures and in mouse leukemia have been found in two stable pig kidney cell lines, PK-13 and IB-RS-2. The particle's average outer diameter is c. 90 m, while the core is c. 60 m.     

The nitric oxide pathway in pre-eclampsia: pathophysiological implications

Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with N^G-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined.