Behavioural and neurochemical sensitization of morphine-withdrawn rats to quinpirole

The sensitivity of dopamine D2-like receptors in morphine-withdrawn rats was studied using the selective agonist quinpirole. Morphine was administered twice daily increasing the daily dose from 20 to 50 mg/kg during 7 days. Twenty-four hours after the last morphine administration the rats were given quinpirole (0.01-1 mg/kg) and their behavior was assessed. Withdrawal from repeated morphine treatment enhanced yawning behavior and penile erections induced by small doses (0.01-0.1 mg/kg) as well as the intensity of stereotypy induced by a large dose (1.0 mg/kg) of quinpirole. In the morphine-withdrawn rats the dose of 1 mg/kg of quinpirole caused less yawning than in the control rats, whereas the number of erections induced by this dose was enhanced as compared with the control animals. In the control rats, the striatal and limbic concentrations of dopamine metabolites, 3,4-dihydroxphenylacetic acid (DOPAC), and homovanillic acid (HVA), were not clearly affected by the smallest dose of quinpirole. However, the small dose of quinpirole (0.01 mg/kg) significantly reduced the levels of DOPAC and HVA in the striatum and limbic forebrain of the rats withdrawn from morphine either for 24 or 48 h. These findings indicate that withdrawal from repeated morphine treatment enhances the sensitivity of dopamine D2-like receptors.     

Acute cocaine results in rapid rises in intracellular free calcium concentration in canine cerebral vascular smooth muscle cells: possible relation to etiology of stroke

We report the outcome of 177 consecutive primary Charnley total hip arthroplasties inserted with Boneloc cement between November 1991 and November 1993. There were 107 women and 70 men. The mean age at the time of the operation was 71 years. 11 patients (13 hips) died during the follow-up period and 3 patients were too weak to attend a follow-up examination. Of the 161 remaining hips, 4 had been revised because of deep infection. The mean follow-up time for the remaining 157 hips was 2 (0.5-3) years. 24 hips had been revised and 6 are waiting for revision because of stem loosening. Of the remaining 127 hips, 72 showed radiographic signs of stem loosening and 2 hips were probably loose. Osteolysis was seen around the femoral component in 56 hips.     

Calcium, magnesium, and potassium in hair of deer from areas of contrasting soil productivity

The endothelium, lining the inner surface of blood vessels, can be considered as the main local regulator of vascular wall homeostasis. It secretes various factors in response to mechanical and hormonal stimuli, which, in turn, influence smooth muscle cell contractility, vascular structure, blood fluidity, and other cell-to-cell interactions. Within the same species, there are, however, variations in endothelial cell function, depending not only on the vascular bed of origin, but also on the size of the vessel within the same vascular territory. Differences have been observed in phenotype, antigen expression, cell size and growth, secretory function, and G-protein expression. Furthermore, some pathological processes affect endothelial function selectively; that is, some vascular beds are sensitive to atherosclerosis while others are not. Understanding these distinctions is particularly important for a rational approach to the treatment of vascular disorders.     

Thermofluid-neutronic stability of the rotating, fluidized bed, space-power reactor

A rotating fluidized bed nuclear reactor has the potential of being a vary attractive option for ultra-high power space systems, especially for propulsion. Research has already examined fuel bed expansion due to variations in state variables, propellant flow rate, and rotational speed, and has also considered problems related to thermal stress. This paper describes the results of a coupled thermofluid-neutronic analysis where perturbations in fuel bed height caused by maneuvering changes in operating conditions alter power levels due to varying absorption of neutrons which would otherwise leak from the system, mainly through the nozzle. This first analysis was not a detailed stability analysis. Rather, it utilized simplified neutronic methods, and was intended to provide an order-of-magnitude assessment of the stability of the reactor with the intention to determine whether or not stability might be a “concept killer”.Stability was compared with a fixed-fuel-bed reactor of identical geometry for three different cases comprising a set of small, medium and large sizes/powers from 250 MW to 5 GW. It was found that power fluctuations in the fluidized bed reactor were larger by 100 db or more than expected in a packed bed reactor of the same geometry, but never resulted in power excursions. Margins to unit gain in some cases, however, were sufficiently small that the approximations in this quasi-2-dimensional model may not be sufficiently accurate to preclude significant excursions.     

Intranodal hemorrhagic spindle cell tumor

We describe an example of a rare benign intranodal haemorrhagic spindle cell tumour (also called intranodal myofibroblastoma), occurring in a lymph node of the right inguinal region of a 53 year-old male patient. This is the first documentation of this tumour in the Danish literature. The lesion presents typically as a unilateral, solitary, painless inguinal lump. The microscopic appearance is characterized by proliferating spindle-shaped cells, interstitial haemorrhage and amianthoid fibers. Differential diagnosis includes primary and secondary lymph node tumours, such as Kaposi's sarcoma; metastatic spindle cell carcinoma; melanoma; neurilemmoma and soft tissue sarcomas. The clinical behaviour of the tumour is benign and local excision is the treatment of choice.     

The installation and support of internationally distributed equipment for people with dementia

This paper describes the evaluation and support of assistive technology designed to increase the independence of people with dementia. Devices were evaluated by people with dementia in their own homes. Working with and supporting people with dementia requires relational skills not normally needed by installers and technical supporters.     

Imitation, copying, and the use of models: report writing in an introductory physics course

The article focuses on the use and misuse of models-both appropriate and inappropriate-in the report-writing practices of first year physics students, especially those from non-English speaking backgrounds. It analyzes the students' propensity to use any available text on a given topic as a source of model sentences. Examples of "copying" are provided and analyzed. It is argued that many forms of copying are legitimate learning strategies of novice writers, for the production of certain kinds of texts, but that this can become a problem when inappropriate models are used or when appropriate models are used inappropriately. Copying is discussed in relation to imitative learning and modeling as well as plagiarism, and some suggestions to improve teaching practice are made.