Effects of pretraining and water temperature on female rats' performance in the Morris water maze.

The water maze is a complex spatial task that requires the coordination of multiple systems to perform efficiently. Various factors have been shown to influence performance in this task, including motivational state and prior experience. Although a consistent sex difference has been observed in acquiring the water maze in rats, the contribution of the various factors in female rat performance has not been fully assessed. Therefore, the current study tested the effects of motivation as manipulated by water temperature of the maze and prior experience in the maze on the performance of female rats. It was hypothesized that females pretrained in the maze would perform better than those without exposure to the water maze, regardless of water temperature, but in naïve rats, colder water would improve performance as shown previously in male rats. For pretraining, female rats were taught to find a visible platform in cold (19 °C, 4 trials on one day) and warm (25 °C, 4 trials on one day) water before acquisition trials, with the order of the water temperature randomly assigned. Control rats were not given any training and were naïve to the water maze procedure. Pretrained and control rats were then tested to locate a hidden platform in either cold or warm water for 5 consecutive days. Overall, pretraining had a significant effect on distance, latency, and directness of path to the platform. Water temperature did not show a significant effect on any measure or a significant interaction with pretraining. Thus, while our hypothesis that pretraining would improve performance was supported, the results did not support the prediction that water temperature would also significantly influence performance. These results show that non-spatial pretraining can critically improve the performance of females in acquiring a place strategy for the hidden platform, irrespective of water temperature.

Advancing my health care practice in aromatherapy.

This paper describes a clinical trial to examine the effects of aromatherapy on stress reduction in haemodialysis patients. The author used a social readjustment rating scale (SRRS), health assessment questionnaire and reflective journal in the collection and analysis of data.

Acrylic resins reinforced with woven highly drawn linear polyethylene fibres. 2. Water sorption and clinical trials.

The results reported in this paper are part of a continuing study of the reinforcement of acrylic denture base resins with highly drawn linear polyethylene fibres. Water sorption is significantly reduced by incorporation of these fibres, even though the water diffusion processes as such remain broadly unaffected. Clinical trials are encouraging and the reinforced dentures have been well accepted by all the patients.

Acrylic resins reinforced with highly drawn linear polyethylene woven fibres. 1. Construction of upper denture bases.

This paper presents a detailed description of the construction of complete acrylic upper dentures reinforced with highly drawn linear polyethylene fibres. The work forms part of a continuing project to elucidate the properties and potential of the new system.

Diastema preservation in resin-bonded fixed partial dentures.

The etched-metal, resin-bonded fixed partial denture has evolved rapidly from its origination as an extracoronal splint. Technologic advancements in both resin chemistry and retentive surface etching techniques have markedly improved the quality of the prosthesis. Today, resin-bonded fixed partial dentures are an effective, conservative means of replacing missing teeth when specific contra-indications--long spans, insufficient sound enamel, malocclusion, pathologic occlusal habits--are identified and avoided. A universally-accepted standard preparation does not exist for resin-bonded fixed partial dentures; rather, common principles of tooth reduction are agreed upon by most authors. This case report details necessary modifications in typical preparation and framework design that must be included to maintain a midline diastema when such spacing is required or preferred by the patient.

Numerical models of extragalactic radio sources.

Numerical simulations with supercomputers allow analysis of the wide range of nonlinear physics inherent in the hydrodynamic and magnetohydrodynamic equations. When applied to extragalactic radio sources, these numerical models have begun to reproduce many of the complex structures observed on telescopic images. This combination of telescopic and numerical observations provides powerful probes of the physics of radio galaxies. In this review, some of the recent results from both two-dimensional and three-dimensional numerical simulations of the formation and evolution of extended radio morphologies are described. These numerical models have allowed the exploration of important physical phenomena including the role of magnetic fields in the dynamics and emissivity of extended radio galaxies, intermittent outflow from the cores of active galaxies, instabilities and disruption of fluid jets, and the bending of collimated outflows by motion through the intergalactic medium.

Protection of agammaglobulinemic piglets from porcine rotavirus infection by antibody against simian rotavirus SA-11.

Rotavirus, a double-stranded RNA virus, has been implicated as a diarrhea-provoking agent in a variety of animal species. Several previous reports have shown that immunization with a single serotype may result in increased in vitro neutralization titers against serotypes not represented in the immunogen. This study was undertaken to determine whether antibody from cows immunized against simian rotavirus strain SA-11 (which is alien to pigs) could protect neonatal piglets from infection with a North Carolina isolate of porcine rotavirus. Accordingly, cows were immunized with SA-11 and an immunoglobulin G (IgG)-rich fraction was isolated from their colostrum. An IgG-rich fraction was similarly isolated from colostrum of nonimmunized cows. At equal concentrations, IgG from SA-11-immunized cows had two- to fourfold higher neutralization titers to seven of eight test strains of rotavirus, including SA-11 (serotype 3); human rotavirus serotypes 1, 3, and 4; North Carolina porcine rotavirus (serotype undetermined); Ohio State porcine rotavirus (serotype 5); and bovine rotavirus (serotype 6). The IgG-rich fractions were fed as dietary supplements to agammaglobulinemic piglets infected with the North Carolina porcine rotavirus. IgG from the SA-11-immunized cows was about eightfold more effective in protecting piglets than was IgG from nonimmunized cows.

Pharmacokinetics of xamoterol after intravenous and oral administration to volunteers.

The pharmacokinetics of xamoterol, a beta-adrenoceptor partial agonist under clinical evaluation for the treatment of mild to moderate heart failure, have been studied in 12 healthy male subjects. They received 14 mg i.v. and oral doses of 50 and 200 mg as a tablet and 200 mg as a solution in a 4 way cross-over design. After i.v. dosing the elimination half-life was 7.7 h, the total body clearance was 224 ml.min-1 and the volume of distribution at steady-state (Vss) was 48 l. Sixty-two percent of the dose was recovered unchanged in urine. After oral doses, the absolute bioavailability of xamoterol was shown to be 5% irrespective of whether the dose was administered as a tablet or solution. Peak plasma concentrations occurred at about 2 h for the tablet dose and slightly earlier (1.4 h) for the solution. Peak plasma concentration, AUC and urinary recovery of unchanged drug increased in proportion to dose. The apparent elimination half-life after oral doses (16 h) was significantly longer than that observed after an intravenous dose. Despite the low bioavailability, the degree of inter-subject variability of oral bioavailability was small probably indicating that the controlling factor is the hydrophilic nature of the molecule rather than extensive first pass metabolism or poor dissolution of xamoterol from the tablet formulation.

Erythrocyte cation cotransport and countertransport in essential hypertension.

We studied erythrocyte cation cotransport and countertransport systems in 21 and 27 patients with essential hypertension, respectively, all of whom were under 50 years of age, had a diastolic blood pressure level greater than 100 mm Hg, and had a family history of hypertension. The following parameters were normal in nearly all patients: total erythrocyte Na+ and K+ concentrations, the maximal rate (Vmax) of inward cotransport, the affinity of cotransport with Rb+ as the substrate, the net outward cotransport of Na+ ions, the passive "leak" influx of Rb,+ and the maximal rate of Li+-Na+ countertransport. Only four patients gave clearly abnormal results; in two the maximal rate of both cotransport and countertransport was double the normal values, while another two patients demonstrated a greater than twofold increase in passive "leak" influx to Rb+ ions. Most of the patients with moderate to severe essential hypertension in this Australian study were characterized by normal erythrocyte cation fluxes, but a few showed elevation of both cotransport and countertransport of cations.

Serum cholesterol levels in selected air force cadets compared with levels in the West Point study.

In the USAFSAM Cardiovascular Disease Followup Study, the surprising rise in average cholesterol levels in West Point cadets during the 6 years following their entry into the U.S. Military Academy in 1952 implied a significant increase in risk of heart disease in later years. To ascertain whether that pattern of change suggested increased risk is characteristic of cadets at military academies, a similar study on a smaller scale was conducted on U.S. Air Force Academy cadets beginning in 1972. Randomly selected cadets were monitored throughout their 4-year training at the U.S. Air Force Academy. Mean levels of serum cholesterol were similar at the beginning and end of the study; values between those times were generally somewhat lower. Average body fat never exceeded 12.6%; the average remained close to 12% during the last 3 years. Possible reasons for the differences between the pattern of change in serum cholesterol in the West Point cadets in earlier years (1952-56) and in the U.S. Air Force Academy cadets are discussed. Differences in exercise or stress levels were ruled out as likely explanations. Changes in dietary fat intakes may account for the differences, while unidentified changes in the social environment are possible contributory factors.

Inactivation of metronidazole by anaerobic and aerobic bacteria.

The rate of inactivation of metronidazole in vitro was determined during the course of time-kill curves against anaerobic and aerobic bacteria in the stationary phase of growth. Metronidazole at a concentration of 10 mug/ml, as measured by bioassay, was rapidly inactivated in broth culture by susceptible anaerobic bacteria (minimum bactericidal concentration 1,500 mug/ml). Three of four aerobic bacteria also inactivated metronidazole, although at generally slower rates than the anaerobes, but this was not associated with a bactericidal effect against these organisms. The presence of aerobic bacteria in mixed cultures with Bacteroides fragilis did not, moreover, inhibit the bactericidal activity of metronidazole against the latter organism. However, the possibility still remains that, in vivo, aerobic bacteria capable of inactivating metronidazole could inhibit the action of the drug against anaerobes in mixed infections.

Mixed leukocyte reaction in rheumatoid arthritis.

The mixed leukocyte reaction (MLR) responses of 29 patients with classic rheumatoid arthritis (RA) were compared with those of 24 age- and sex-matched healthy controls. Pools of stimulating cells were selected to include the major cross-reacting HL-A specificities. In pooled human serum the MLR response of the RA lymphocytes was significantly enhanced relative to the response controls (P less than 0.05). In autologous serum there was suppression of the MLR response in patients with RA which correlated with disease activity. The data suggest the presence of an intrinsically enhanced cellular reactivity of RA lymphocytes suppressed by serologic factor(s). The mechanisms of this enhancement of suppression are discussed.