Glutamate induces glutathione efflux mediated by glutamate/aspartate transporter in retinal cell cultures.

This study was undertaken in order to characterize the role of the glutamate/aspartate transporter (GLAST) in the glutathione (GSH) efflux induced by glutamate. Our results demonstrated that retinal cell cultures exhibit two mechanisms of GSH release, one Na(+)-independent and other Na(+)-dependent. Glutamate and aspartate induced GSH efflux only in presence of Na(+). Treatment with PCD (L-trans-Pyrrolidine-2,4-dicarboxylate), a transportable glutamate uptake blocker, increased GSH release indicating that GSH can be carried by glutamate transporters in retinal cell cultures. Added to this, treatment with zinc ion cultures, a recognized inhibitor of GLAST blocked GSH efflux evoked by glutamate. Treatment with NMDA antagonist (MK-801) did not have any effect on the GSH release induced by glutamate. These results suggest that glutamate induces GLAST-mediated release of GSH from retinal cell cultures and this could represent an important mechanism of cellular protection against glutamate toxicity in the CNS.

Local inhibition of nitrergic activity in tenotomized rats accelerates muscle regeneration by increasing fiber area and decreasing central core lesions.

Muscular atrophy is a progressive degeneration characterized by muscular proteolysis, loss of mass and decrease in fiber area. Tendon rupture induces muscular atrophy due to an intrinsic functional connection. Local inhibition of nitric oxide synthase (NOS) by Nω-nitro-L-arginine methyl ester (L-NAME) accelerates tendon histological recovery and induces functional improvement. Here we evaluate the effects of such local nitrergic inhibition on the pattern of soleus muscle regeneration after tenotomy. Adult male Wistar rats (240 to 280 g) were divided into four experimental groups: control (n=4), tenotomized (n=6), vehicle (n=6), and L-NAME (n=6). Muscular atrophy was induced by calcaneal tendon rupture in rats. Changes in muscle wet weight and total protein levels were determined by the Bradford method, and muscle fiber area and central core lesion (CCL) occurrence were evaluated by histochemical assays. Compared to tenotomized (69.3±22%) and vehicle groups (68.1%±17%), L-NAME treatment induced an increase in total protein level (108.3±21%) after 21 days post-injury. A reduction in fiber areas was observed in tenotomized (56.3±1.3%) and vehicle groups (53.9±3.9%). However, L-NAME treatment caused an increase in this parameter (69.3±1.6%). Such events were preceded by a remarkable reduction in the number of fibers with CCL in L-NAME-treated animals (12±2%), but not in tenotomized (21±2.5%) and vehicle groups (19.6±2.8%). Altogether, our data reveal that inhibition of tendon NOS contributed to the attenuation of atrophy and acceleration of muscle regeneration.

Brain-derived neurotrophic factor inhibits osmotic swelling of rat retinal glial (Müller) and bipolar cells by activation of basic fibroblast growth factor signaling.

Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Intravitreal administration of neurotrophins such as brain-derived neurotrophic factor (BDNF) is known to promote survival of retinal neurons. Here, we show that exogenous BDNF inhibits the osmotic swelling of Müller cell somata induced by superfusion of rat retinal slices or freshly isolated cells with a hypoosmotic solution containing barium ions. BDNF also inhibited the osmotic swelling of bipolar cell somata in retinal slices, but failed to inhibit the osmotic soma swelling of freshly isolated bipolar cells. The inhibitory effect of BDNF on Müller cell swelling was mediated by activation of tropomyosin-related kinase B (TrkB) and transactivation of fibroblast growth factor receptors. Exogenous basic fibroblast growth factor (bFGF) fully inhibited the osmotic swelling of Müller cell somata while it partially inhibited the osmotic swelling of bipolar cell somata. Isolated Müller cells displayed immunoreactivity of truncated TrkB, but not full-length TrkB. Isolated rod bipolar cells displayed immunoreactivities of both TrkB isoforms. Data suggest that the neuroprotective effect of exogenous BDNF in the retina is in part mediated by prevention of the cytotoxic swelling of retinal glial and bipolar cells. While BDNF directly acts on Müller cells by activation of TrkB, BDNF indirectly acts on bipolar cells by inducing glial release of factors like bFGF that inhibit bipolar cell swelling.

Morfoanatomia do eixo vegetativo aéreo de Ayapana triplinervis (Vahl) R.M. King & H. Rob. (Asteraceae) / Morphoanatomy of the vegetative aerial axis of Ayapana triplinervis (Vahl) RM King & H. Rob. (Asteraceae)

Ayapana triplinervis (Asteraceae) é uma erva medicinal da Amazônia conhecida como "Japana branca" e "Japana roxa" utilizada como tônico, digestivo, antidiarréico dentre outros. Objetivou-se caracterizar neste estudo a morfoanatomia caulinar e foliar de A. triplinervis, para corroborar se esta espécie apresenta morfotipos, além de fornecer dados para sua identificação. Amostras foram coletadas no Horto de Plantas Medicinais da Universidade Federal Rural da Amazônia e Embrapa Amazônia Oriental, analisadas morfologicamente e segundo técnicas usuais em anatomia vegetal. O caule é cilíndrico branco ou roxo, com epiderme unisseriada persistente e endoderme com bainha amilífera e estrias de Caspary. As folhas são simples, opostas, triplinervadas, com base atenuada ou decorrente. Possuem estômatos anomocíticos, cera em placas ou granular, glândulas peroladas, mesofilo dorsiventral com feixes colaterais e ductos secretores. A. triplinervis apresentou caracteres morfoanatômicos diferentes entre os tipos branca e roxa, o que possibilita a distinção dos dois morfotipos.

Ayapanatriplinervis (Asteraceae), also known as "Japana branca" and "Japana roxa" in Brazil, is a medicinal herb from the Amazon used as tonic, digestive, antidiarrheal, among others. This study aimed to characterize the morphoanatomy of the aerial vegetative axis of A. triplinervis to corroborate that this species has morphotypes, in order to provide data for their identification. Samples were collected in the Garden of Medicinal Plants of the Federal Rural University of Amazônia and Embrapa Amazônia Oriental, and they were analyzed morphologically and by the standardtechniques of plant anatomy. The stem is cylindrical, white or purple, with uniseriate epidermis, trichomes and endoderm with starch sheath and Casparian strips. The leaves are simple, opposite, with attenuate or arising basis; they have anomocytic stomata, epicuticular wax plates or granules, pearl glands, dorsiventral mesophyll with collateral vascular bundles and secretory ducts. Ayapana triplinervis showed different morphoanatomical features betweenthe white and purple types, which enablesthe distinction between the two morphotypes.

Experimental airborne transmission of Salmonella Agona and Salmonella Typhimurium in weaned pigs.

This study tested the hypothesis of airborne transmission of Salmonella Agona (Trial I) and Salmonella Typhimurium (Trial II) in weaned pigs. The trials were performed using stainless-steel/glass isolation cabinets connected by air ducts to permit an unidirectional airflow from cabinet 1 (two control pigs) to cabinet 3 (two sentinel pigs), passing through cabinet 2 (two inoculated pigs). Air samples, pooled faecal samples from the floor and rectal swabs were collected daily and assessed by culture and PCR. A fumigation chamber and rubber gloves coupled to the cabinets allowed sampling without opening the system. Trials I and II lasted 15 and 19 days respectively. The recovery of S. Agona and S. Typhimurium and detection of seroconversion in sentinel pigs indicate that airborne Salmonella transmission in weaned pigs over short distances is possible. Further studies on the role of aerosols in the epidemiology of Salmonella in intensive pig production should be performed.

Physician response to a prediction rule for the triage of emergency department patients with chest pain.

OBJECTIVE: To determine the response of physicians to a noncoercive prediction rule for the triage of emergency department patients with chest pain. DESIGN: Prospective time-series intervention study. SETTING: A university hospital emergency department. PARTICIPANTS/PATIENTS: 68 physicians, all of whom were responsible for the triage of at least one of 252 patients presenting to the emergency department with a chief complaint of acute chest pain. INTERVENTION: A previously validated algorithmic prediction rule that was attached to the back of patient data forms in the emergency department. MEASUREMENTS: Patients' clinical data were recorded by the examining physician in the emergency department or by a research nurse blinded to patient outcome. The physicians recorded their own estimates of the risk of acute myocardial infarction and their reactions to the prediction rule in a self-administered questionnaire completed at the time of triage. MAIN RESULTS AND CONCLUSIONS: The physicians reported that they looked at the prediction rule during the triage of 115 (46%) of the 252 patients. The likelihood of using the prediction rule decreased significantly with increasing level of physician training. The most common reasons given for disregarding the prediction rule were confidence in unaided decision making and lack of time. The physicians reported that of the 115 cases for which the prediction rule was used, only one triage decision (1%) was changed by it. Future research should explore how prediction rules can be designed and implemented to surmount the barriers highlighted by these data.

Failure of information as an intervention to modify clinical management. A time-series trial in patients with acute chest pain.

OBJECTIVE: To test whether a low-intensity, nonintrusive intervention improved the efficiency of management of patients with acute chest pain. DESIGN: Time-series trial with six 14-week cycles, each including a 5-week intervention period and a 5-week control period separated by 2-week "washout" periods. SETTING: Urban teaching hospital. PATIENTS: 1921 patients aged 30 years or older with acute chest pain unexplained by local trauma or chest radiograph. INTERVENTION: Risk estimates and triage recommendations were made available to physicians at the time of emergency department evaluation and, for hospitalized patients, on a daily basis before morning rounds. Flowsheets and stickers, but no direct human contact, were used to transmit this information. MEASUREMENTS: Rates of admission to the hospital and coronary care unit, inpatient costs, and lengths of stay. RESULTS: Rates of admission during intervention and control periods were similar in both the hospital (52% and 51%, respectively) and the coronary care unit (10% and 10%, respectively). Total lengths of stay in the hospital were similar (4.9 +/- 5.9 days and 4.9 +/- 5.7 days, respectively), as were average total costs ($7822 +/- $13,217 and $7955 +/- $13,400, respectively). No differences in management were detected for the subgroup of patients with low clinical risk for acute myocardial infarction. CONCLUSIONS: The use of information alone--without direct human contact--did not affect management of patients with acute chest pain at this hospital. Although this low-intensity intervention might be more effective for other conditions and in other settings, our data support the use of other strategies to affect physician decision making.

Triage decisions for emergency department patients with chest pain: do physicians' risk attitudes make the difference?

OBJECTIVE: To determine whether physicians' risk attitudes correlate with their triage decisions for emergency department patients with acute chest pain. DESIGN: Cohort. SETTING: The emergency department of a university teaching hospital. PATIENTS: Patients presenting to the emergency department with a chief complaint of acute chest pain. PHYSICIANS: All physicians who were primarily responsible for the emergency department triage of at least one patient with acute chest pain from July 1990 to July 1991. METHODS: The physicians' risk attitudes were assessed by two methods: 1) a new, six-question risk-taking scale adapted from the Jackson Personality Index (JPI), and 2) the Stress from Uncertainty Scale (SUS). RESULTS: The physicians who had high risk-taking scores ("risk seekers") admitted only 31% of the patients they evaluated, compared with admission rates of 44% for the medium scores and 53% for the physicians who had low risk-taking scores ("risk avoiders"), p < 0.001. After adjustment for clinical factors, the patients triaged by the risk-seeking physicians had half the odds of admission [odds ratio (OR) 0.51, 95% confidence interval (95% CI) 0.27 to 0.97], and the patients triaged by the risk-avoiding physicians had nearly twice the odds of admission (OR 1.83, 95% CI 1.10 to 3.03) of the patients triaged by the medium-risk scoring physicians. The SUS did not correlate significantly with admission rates. Of the 92 patients released home by the risk-seeking physicians, 91 (99%) were known to be alive four to six weeks afterwards and one was lost to follow-up; among the 66 patients released by the risk-avoiding physicians, 64 (97%) were known to be alive at four to six weeks, one was lost to follow-up, and one died of ischemic heart disease during a subsequent hospitalization (p = NS). CONCLUSIONS: The physicians' risk attitudes as measured by a brief risk-taking scale correlated significantly with their rates of admission for emergency department patients with acute chest pain. These data do not suggest that the risk-seeking physicians achieved lower admission rates by releasing more patients who needed to be in the hospital, but an adequate evaluation of the appropriateness of triage decisions of risk-seeking and risk-avoiding physicians will require further study.

Comparação da eficiência dos caldos de enriquecimento seletivo no isolamento de Salmonella Dublin / Comparison of the efficiency of selective enrichment broths for Salmonella Dublin isolation

The aim of this study was to compare three different selective enrichment broths: Rappaport-Vassiliadis (RV), selenite cystine (SC) and Muller-Kauffmann tetrathionate (MKT) for Salmonella Dublin isolation from faecal samples of calf experimentally infected. The bacteriological procedure involved pre-enrichment stages in Hajna-GN broth (only for the samples inoculated in RV broth), selective enrichment, culture in modified brilliant green agar (BGA), presumptive biochemistry tests (using triple-sugar-iron agar and lysine-agar) and slide agglutination test with poli-O and poli-H Salmonella antiserum. The effects of enrichment temperatures using RV broth were also evaluated (37ºC and 42ºC). SC broth was significantly more efficient in the isolation of Salmonella Dublin (P<0,05), whereas RV broth incubated at 42ºC had a lower efficiency in the microbiological isolation.