Effects of different perfusates on functional parameters of isolated perfused dog kidneys.

BACKGROUND: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys. In contrast to haemoperfusion, synthetic perfusion media can be standardized and can prevent the initiation of blood-mediated reperfusion reactions. Thus, an additional aim was to determine whether blood could be replaced by synthetic cell-free perfusion solutions. METHODS: Canine kidneys (n = 30) were harvested from donors euthanized in veterinary practices for causes unrelated to the present study. The kidneys were isolated and perfused with autologous blood or cell-free synthetic electrolyte buffer (Tyrode solution). During perfusion, we monitored renal perfusate flow (RPF), glomerular filtration rate (GFR), electrolyte and glucose reabsorption, oxygen consumption and urine concentration. RESULTS: Changes in perfusion medium did not affect the RPF. In contrast, GFR, urine concentration and oxygen consumption were significantly higher, whereas fractional excretion of sodium and glucose were significantly lower in blood- than in Tyrode-perfused kidneys. CONCLUSIONS: This system offers a simple model for studying whole-organ functional alterations after acute renal ischaemia. Renal function indicators were below values reported during in vivo physiological conditions. These functions were better conserved when kidneys were perfused with autologous blood than with Tyrode.     

A systemically administered neurotensin agonist blocks disruption of prepulse inhibition produced by a serotonin-2A agonist.

Prepulse inhibition (PPI) of the startle reflex can be disrupted by drugs that act as agonists at the serotonin (5-HT) 2A receptor, such as DOI, and this effect is blocked by drugs that inhibit 5-HT2A transmission. We tested the effects of systemic administration of PD149163, a neurotensin agonist, on DOI-induced disruption of PPI in Sprague-Dawley rats. PD149163 completely and dose dependently blocked the PPI deficits produced by DOI. These findings suggest that, in addition to their established ability to inhibit dopamine transmission, neurotensin agonists may also inhibit 5-HT2A transmission, a pharmacological feature associated with atypical antipsychotic drugs.     

Differential role of serotonergic projections arising from the dorsal and median raphe nuclei in locomotor hyperactivity and prepulse inhibition.

While an involvement of brain serotonin systems in schizophrenia has been suggested by many studies, the relative role of different serotonergic projections in the brain remains unclear. We therefore examined the effects of selective brain serotonin depletion on psychotropic drug-induced locomotor hyperactivity and prepulse inhibition, two animal models of aspects of schizophrenia. Pentobarbital-anesthetized (60 mg/kg, i.p.) male Sprague-Dawley rats were stereotaxically microinjected with 1 microl of a 5 microg/microl solution of the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into either the dorsal or median raphe nucleus. At 2 weeks after the surgery, rats with dorsal raphe lesions did not show changes in psychotropic drug-induced locomotor hyperactivity, but displayed partial disruption of prepulse inhibition. In contrast, rats with median raphe lesions showed significant enhancement of phencyclidine-induced, but not amphetamine-induced locomotor hyperactivity and a marked disruption of prepulse inhibition. These results provide evidence for differential involvement of serotonergic projections in locomotor hyperactivity and prepulse inhibition. This study may help to explain the role of different serotonin projections in the brain in the pathophysiology of schizophrenia.     

Use of recombinant factor VIIa in infants with severe coagulopathy.

The risk of hemorrhage in infants with severe coagulopathies unresponsive to fresh frozen plasma (FFP) infusions may preclude therapeutic invasive interventional procedures. We describe the successful use of recombinant factor VIIa (rFVIIa) in two such infants, the first with cirrhosis requiring paracentesis and the second with necrotizing enterocolitis requiring laparotomy. This report reviews the current concepts on the mechanism of action of the drug rFVIIa and considers its expanded use in infants unresponsive to FFP replacement.     

Parenting stress among caregivers of children with congenital cataracts.

OBJECTIVE: To examine parenting stress among caregivers of young children with congenital cataracts and to assess whether diagnostic and/or treatment differences are associated with differences in perceived parenting stress. METHODS: Parents of 41 preschool-age children with congenital cataracts (13 with bilateral cataracts [BCCs] and 28 with unilateral cataracts [UCCs], of whom 14 were aphakic and 14 were pseudophakic) completed the Parenting Stress Index (PSI) and/or a disease-specific parental stress measure, ie, the Ocular Treatment Index (OTI). RESULTS: The 28-item OTI had excellent internal consistency (alpha = 0.94) and supported three of four a priori validity hypotheses. Parents of children with congenital cataracts reported normal parenting stress levels on the PSI. Parents of children with UCCs tended to report higher levels of stress, but not significantly so, than did parents of children with BCCs. Among parents of children with UCCs, those whose children were aphakic reported higher levels of stress on the OTI and all of the PSI subscales than did parents of pseudophakic children. These differences were statistically significant for two subscales (Adaptability [P =.03] and Mood [P =.01]). CONCLUSIONS: Although parents of children with congenital cataracts generally did not report increased parenting stress levels, clinicians should be aware that parenting stress can adversely impact patients' families. We did observe higher stress levels in parents with children who had UCCs and did not receive an intraocular lens-particularly stress related to their child's reaction to sensory stimulation and mood-compared with parents of pseudophakic children. Thus, clinicians may want to consider parenting stress levels when choosing a treatment for children with UCCs, especially because such stress has been associated with poor treatment compliance for children with other chronic conditions.     

Basic sciences in problem-based learning and conventional curricula: students' attitudes

The purpose of this study was to compare the attitudes toward basic sciences of students in a preclinical problem-based curriculum and a conventional lecture-based curriculum at the end of their second year of medical school. The results showed that the PBL class had more positive attitudes toward basic sciences than students in the conventional class. These results may reflect a learning environment where students meet many scientist role models as teachers and where basic science is learnt in the context of clinical problems.     

Assessment of immunization as a technique to extend the chilled storage life of vacuum‐packaged lamb

The growth at — 1.5°C of Lactobacillus delbrueckii, a meat spoilage organism, was evaluated on vacuum‐packaged lamb legs obtained from animals immunized against that organism. Growth was significantly lower than that on similarly treated legs obtained from non‐immunized lambs. These findings suggest that immunization against spoilage organisms may contribute toward increasing the chilled storage life of fresh meat.     

A small angle light scattering device for planar connective tissue microstructural analysis

The planar fibrous connective tissues of the body are composed of a dense extracellular network of collagen and elastin fibers embedded in a ground matrix, and thus can be thought of as biocomposites. Thus, the quantification of fiber architecture is an important step in developing an understanding of the mechanics of planar tissues in health and disease. We have used small angle light scattering (SALS) to map the gross fiber orientation of several soft membrane connective tissues. However, the device and analysis methods used in these studies required extensive manual intervention and were unsuitable for largescale fiber architectural mapping studies. We have developed an improved SALS device that allows for rapid data acquisition, automated high spatial resolution specimen positioning, and new analysis methods suitable for large-scale mapping studies. Extensive validation experiments revealed that the SALS device can accurately measure fiber orientation for up to a tissue thickness of at least 500 μm to an angular resolution of∼1^o and a spatial resolution of±254 μm. To demonstrate the new device’s capabilities, structural measurements from porcine aortic valve leaflets are presented. Results indicate that the new SALS device provides an accurate method for rapid quantification of the gross fiber structure of planar connective tissues.