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1.
J Fish Biol ; 88(5): 2067-74, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27060882

RESUMO

A combination of mark-recapture and genetic sampling was used to extend the minimum longevity of an elasmobranch species and the life span estimate of the lemon shark Negaprion brevirostris was increased conservatively from 20·2 to 37 years. This increase in longevity means higher vulnerability and a longer recovery time from exploitation.


Assuntos
Longevidade , Tubarões/genética , Animais , Feminino , Viviparidade não Mamífera
2.
J Fish Biol ; 87(6): 1322-41, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26709210

RESUMO

This study documents and discusses recent (2002-2015) sightings and captures of smalltooth sawfish Pristis pectinata in the Bahamas. Movement patterns and habitat preferences of five P. pectinata are examined: two tracked with acoustic telemetry in Bimini and three tagged with pop-up archival transmitting tags in Andros. Historically, P. pectinata may have been distributed throughout the Bahamas; however, since 2002 only 61 encounters were recorded including: Andros (30), Bimini (19) and a handful across other Islands (12). In Bimini, all P. pectinata were >225 cm (stretched total length, LST) suggesting that it is not used as a nursery area. Pristis pectinata in Andros ranged from c. 80 to 450 cm (LST) indicating that this island might be an important nursery and breeding habitat. Pristis pectinata tracked in both islands remained at depths <3 m, often adjacent to mangrove habitats, displaying residency from 42 days (Bimini) to 180 days (Andros). These preliminary findings confirm the Bahamas as an important habitat for P. pectinata and emphasize the urgent need for national protection and management of this population.


Assuntos
Comportamento Animal , Ecossistema , Rajidae/fisiologia , Animais , Bahamas , Espécies em Perigo de Extinção , Feminino , Comportamento de Retorno ao Território Vital , Masculino , Densidade Demográfica
3.
Dev Psychobiol ; 57(7): 809-17, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26095875

RESUMO

Maternal care experienced during postnatal development predicts long-term neurobiological and behavioral outcomes. However, the cascade of behavioral changes that emerge in response to maternal care has not been elucidated. In the current study, we examine naturally occurring variation in postnatal licking/grooming (LG) in C57BL/6J mice to determine its impact on preweaning maternal and pup behavior, the weaning process, the pace of developmental change, the emergence of social behavior, and indices of anxiety-like behavior in adulthood. Our analyses indicate that lower postnatal LG is associated with truncated and more infrequent maternal behavior during the preweaning period. Moreover, compared to High LG dams, Low LG dams are observed to actively wean their offspring sooner and have offspring that play more frequently. The heightened pace of developmental change observed in offspring of Low LG dams suggests a more rapid transition to behavioral and nutritional independence, which could have implications for future reproductive strategies.


Assuntos
Comportamento Animal/fisiologia , Comportamento Materno/fisiologia , Comportamento Social , Desmame , Animais , Animais Recém-Nascidos , Feminino , Asseio Animal/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
4.
Eur J Clin Microbiol Infect Dis ; 33(1): 135-41, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23907587

RESUMO

Candida osteomyelitis is associated with significant morbidity; however, data on the management of Candida osteomyelitis are limited. The Prospective Antifungal Therapy (PATH) Alliance® registry is a comprehensive, multicenter, prospective, observational registry that collected data on patients with invasive fungal infections between 2004 and 2008. The aim of this descriptive analysis was to evaluate the clinical characteristics, treatment, and outcomes of patients with Candida osteomyelitis. Using the PATH Alliance® registry, we performed a review of all patients with a proven diagnosis of Candida osteomyelitis who received a minimum of 14 days of antifungal treatment and/or a therapeutic surgical intervention (n = 53). The epidemiology, diagnosis, treatment, and outcomes of these patients were assessed at 12 weeks. C. albicans (56.6 %) was the most commonly identified organism, followed by C. parapsilosis (18.9 %), C. glabrata (9.4 %), and C. tropicalis (9.4 %). The mean treatment duration was 54.9 days. Multiple different treatment regimens were administered to patients. These included fluconazole (56.0 %), echinocandins (29.3 %), amphotericin B formulations (10.7 %), and voriconazole (4.0 %). Twenty-eight patients (52.8 %) also had a therapeutic surgical intervention. Clinical response was improved in 38 (71.7 %) patients (43.4 % complete and 28.3 % partial response), stable in 11 (20.8 %), and worse in one (1.9 %); three (5.7 %) patients had unknown response. The 12-week survival rate was 93.8 %. In summary, C. albicans was the predominant pathogen, and fluconazole was the most commonly administered agent. However, treatment patterns vary and remain non-standardized. Concurrent candidemia was infrequent, and 12-week survival was notably good in this series of 53 patients with Candida osteomyelitis.


Assuntos
Antifúngicos/uso terapêutico , Candida/isolamento & purificação , Candidíase/tratamento farmacológico , Candidíase/microbiologia , Osteomielite/tratamento farmacológico , Osteomielite/microbiologia , Adolescente , Adulto , Candida/classificação , Candidíase/epidemiologia , Candidíase/patologia , Criança , Desbridamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteomielite/epidemiologia , Osteomielite/patologia , Estudos Prospectivos , Sistema de Registros , Resultado do Tratamento , Adulto Jovem
6.
Am J Transplant ; 13(7): 1724-33, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23730730

RESUMO

Memory T cells play a central role in mediating allograft rejection and are a rational target for immunosuppressive therapy. Alefacept is a recombinant LFA3/IgG1 fusion protein that reduces the number of memory T cells in both psoriatic lesions and the peripheral circulation of psoriasis patients. This study evaluated the efficacy and safety of alefacept compared with placebo when combined with tacrolimus, mycophenolate mofetil and corticosteroids in de novo renal transplant recipients. Between December 2007 and March 2009 patients were randomized in a double-blind fashion to receive alefacept (n = 105) or placebo (n = 107) for 3 months and were then followed for a further 3 months. The primary efficacy endpoint was the incidence of biopsy-confirmed acute T cell mediated rejection (Banff grade ≥ 1) through Month 6. Memory T cell counts were significantly reduced in the alefacept group from Week 3 to study end compared with placebo. However, there was no significant difference between the alefacept and placebo groups for the primary efficacy endpoint (alefacept, 11.0% vs. placebo, 7.0%, p = 0.3). Patient and graft survival as well as renal function was similar between treatment groups. Safety and tolerability were generally similar between the treatment arms. Malignancy was higher in the alefacept treatment arm.


Assuntos
Rejeição de Enxerto/tratamento farmacológico , Terapia de Imunossupressão/métodos , Transplante de Rim , Metilprednisolona/uso terapêutico , Ácido Micofenólico/análogos & derivados , Proteínas Recombinantes de Fusão/uso terapêutico , Tacrolimo/uso terapêutico , Adolescente , Adulto , Idoso , Alefacept , Biópsia , Criança , Pré-Escolar , Relação Dose-Resposta a Droga , Método Duplo-Cego , Vias de Administração de Medicamentos , Quimioterapia Combinada , Seguimentos , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/patologia , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/uso terapêutico , Metilprednisolona/administração & dosagem , Pessoa de Meia-Idade , Ácido Micofenólico/administração & dosagem , Ácido Micofenólico/uso terapêutico , Proteínas Recombinantes de Fusão/administração & dosagem , Estudos Retrospectivos , Tacrolimo/administração & dosagem , Doadores de Tecidos , Resultado do Tratamento , Adulto Jovem
7.
Horm Behav ; 61(3): 454-61, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22300676

RESUMO

The relationship between anxiety and maternal behavior has been explored across species using a variety of approaches, yet there is no clear consensus on the nature or direction of this relationship. In the current study, we have assessed stable individual differences in anxiety-like behavior in a large cohort (n=57) of female F2 hybrid mice. Using open-field behavior as a continuous and categorical (high vs. low) measure we examined the relationship between the anxiety-like behavior of virgin F2 females and the subsequent maternal behavior of these females. In addition, we quantified oxytocin (OTR) and vasopressin (V1a) receptor density within the lateral septum to determine the possible correlation with anxiety-like and maternal behavior. We find that, though activity levels within the open-field do predict latency to engage in pup retrieval, anxiety-like measures on this test are otherwise not associated with subsequent maternal behavior. OTR density in the dorsal lateral septum was found to be negatively correlated with activity levels in the open-field and positively correlated with frequency of nursing behavior. V1a receptor density was significantly correlated with postpartum licking/grooming of pups. Though we do not find support for the hypothesis that individual differences in trait anxiety predict variation in maternal behavior, we do find evidence for the role of OTR and V1a receptors in predicting maternal behavior in mice and suggest possible methodological issues (such as distinguishing between trait and state anxiety) that will be a critical consideration for subsequent studies of the anxiety-maternal behavior relationship. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.


Assuntos
Ansiedade/metabolismo , Comportamento Materno/fisiologia , Receptores de Ocitocina/metabolismo , Receptores de Vasopressinas/metabolismo , Septo do Cérebro/metabolismo , Animais , Ansiedade/genética , Ansiedade/psicologia , Autorradiografia , Comportamento Animal/fisiologia , Comportamento Exploratório/fisiologia , Feminino , Asseio Animal , Individualidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/fisiologia , Receptores de Ocitocina/genética , Receptores de Vasopressinas/genética , Comportamento Social
8.
Res Q Exerc Sport ; 80(1): 1-11, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19408462

RESUMO

The AAHPER Youth Fitness Test, the first U.S. national fitness test, was published 50 years ago. The seminal work of Krause and Hirschland influenced the fitness world and continues to do so today. Important youth fitness test initiatives in the last half century are summarized. Key elements leading to continued interest in youth fitness testing at the start of the 21st century include (a) concerns about children and youth fitness levels, (b) AAHPER(D)-led youth fitness battery development, (c) differentiation between performance-related and health-related fitness testing, (d) the numerous youth fitness tests developed, (e) collaborative discussions on development and adoption of a unified national youth fitness battery, (f) computerization of youth fitness test results, (g) differentiation between norm-referenced and criterion-referenced evaluation of student results, and (h) concern about youth fitness levels (again, but with a focus on health). We have come full circle on youth fitness interests. This article summarizes the key youth fitness tests in the second half of the 20th century and projects future considerations.


Assuntos
Teste de Esforço/história , Promoção da Saúde , Aptidão Física , Marketing Social , Adolescente , Criança , Proteção da Criança/história , Pré-Escolar , Teste de Esforço/normas , Feminino , Promoção da Saúde/história , História do Século XX , História do Século XXI , Humanos , Masculino , Atividade Motora , Fatores de Tempo , Estados Unidos
9.
Am J Med Sci ; 328(2): 78-83, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15311165

RESUMO

BACKGROUND: Genetic and environmental hypotheses may explain why normotensive persons at high risk of developing hypertension often exhibit greater cardiovascular reactivity to stressors than those at low risk. METHODS: Pearson's correlation was used to evaluate reproducibility and independent t test to compare the cardiovascular responses to 30 W of exercise of normotensive young adult African-American women with positive and negative parental histories (PH) of hypertension (PH, n = 23; PH, n = 20). RESULTS: Correlations were significant for duplicate measurements. The effects of PH on blood pressure measured at rest and during exercise were not statistically significant (P > 0.1). A nearly significant trend for greater resting (.-)VO(2) (P = 0.08) was detected in the PH than in the PH group (3.67 +/- 0.18 versus 3.26 +/- 0.14 mL/kg/min). CONCLUSION: A hyper-reactive blood pressure response to exercise, characteristic of the evolution of hypertension, may not be present among the normotensive female offspring of hypertensive African Americans. The significance of an 11% intergroup difference in the mean resting (.-)VO(2) observed in this study is unclear.


Assuntos
Pressão Sanguínea , Exercício Físico , Hipertensão/genética , Hipertensão/patologia , Adolescente , Adulto , Negro ou Afro-Americano , População Negra , Sistema Cardiovascular , Estudos de Coortes , Saúde da Família , Feminino , Frequência Cardíaca , Humanos , Oxigênio/metabolismo , Pais , Estados Unidos
10.
Blood Press ; 11(4): 229-34, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12361191

RESUMO

An exaggerated exercise blood pressure response (EEBPR) may be associated with an increased risk of hypertension. We hypothesized that aerobic exercise training can decrease EEBPR and the risk for hypertension by decreasing arterial resistance. We studied the effects of aerobic training on the submaximal exercise blood pressure (BP) of eight normotensive young adult African-American men with an EEBPR. Subjects were trained on a stationary bicycle at an intensity of 70% peak oxygen uptake (VO2peak), for 30 min, three times per week, for 8 weeks. BP, heart rate, cardiac output (CO), stroke volume (SV) and total peripheral vascular resistance (TPR) were measured at rest and during submaximal exercise at a work intensity of 50% VO2peak. Significance of the training effects were evaluated by comparing the pre- and post-training measures (t-test, p < 0.05). A 15% post-training increase in VO2peak (34.6 +/- 1.4 to 40 +/- 1.4 ml/kg/min) and a 9.5 ml post-training increase in mean resting stroke volume were found. A 16.2 mmHg decrement in mean systolic BP, an 11.5 mmHg decrement in mean diastolic BP, a 120 dyne/s/cm5 decrement in TPR and a 1.2 l/min increase in CO were detected during the post-training submaximal exercise tests. These results suggest that reductions in TPR may attenuate the EEBPR of normotensive African-American males following an 8-week training regimen of stationary bicycling at 70% VO2peak. Aerobic exercise training may, therefore, reduce the risk of hypertension in normotensive African-American males by the mechanism of a reduction in TPR. Because of the limited number of subjects, the results of this study should be interpreted cautiously pending confirmation by a larger controlled trial.


Assuntos
Pressão Sanguínea/fisiologia , Exercício Físico/fisiologia , Adolescente , Adulto , Negro ou Afro-Americano , Débito Cardíaco , Frequência Cardíaca , Humanos , Masculino , Troca Gasosa Pulmonar , Volume Sistólico , Resistência Vascular
11.
Ethn Dis ; 11(2): 217-23, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11455996

RESUMO

The aim of our study was to examine whether there is an association between blood pressure reactivity to the cold pressor test in African Americans who engaged in different levels of physical activity. We examined the systolic pressure, diastolic pressure, mean arterial blood pressure, heart rate, cardiac index, total peripheral resistance, and forearm blood flow during a two-minute cold pressor test in 15 aerobic, physically active and 15 physically inactive, normotensive young adult African-American males. Peak oxygen consumption varied as a function of physical activity, and was significantly higher in the physically active than in the physically inactive subjects (54.5 +/- 1.5 vs 36.8 +/- 0.7 ml kg(-1) min(-1)) (P<.05). During the cold pressor test, consisting of immersing the foot in ice water, the change in cardiovascular responses were similar between the physically active and the physically inactive groups. These results suggest that regular physical activity may not contribute to an attenuated blood pressure response to behavioral stress of the cold pressor test in normotensive young adult African-American males.


Assuntos
Negro ou Afro-Americano , Pressão Sanguínea , Exercício Físico/fisiologia , Estresse Fisiológico/fisiopatologia , Adolescente , Adulto , Temperatura Baixa , Antebraço/irrigação sanguínea , Frequência Cardíaca , Humanos , Masculino , Consumo de Oxigênio , Fluxo Sanguíneo Regional
14.
Ethn Dis ; 9(1): 104-10, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10355479

RESUMO

Exaggerated blood pressure reactivity to behavioral stress has been observed in the African-American population, and such a pressor response is believed to play a role in hypertension. Regular aerobic exercise has been shown to exert an anti-hypertensive effect, and this may alter the blood pressure hyperreactivity observed in African Americans. To test the hypothesis that aerobic exercise attenuates pressor reactivity in African Americans, we studied eight healthy aerobically-trained normotensive African-American females and five similar sedentary females. The stress stimuli consisted of the cold pressor test with the foot immersed in ice water for two minutes. The aerobic exercise training protocol consisted of six weeks of jogging at 60-70% of peak oxygen uptake (VO2peak), three days/week for 35 min/exercise session. Systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, heart rate, cardiac output, total peripheral resistance, and forearm blood flow were measured. Manifestation of a training effect was illustrated by a 24.1 +/- 0.2% increase in VO2peak (26.9 +/- 1.2 mL x kg(-1) min(-1) vs 35.4 +/- 1.6 mL x kg(-1) min(-1)) (P<.05). Within the exercise-trained group there was a 6.3 +/- .15% decrease in systolic pressure (129 +/- 4.6 mm Hg vs. 121 +/- 5.4 mm Hg) (P<.05), and a 5.0 +/- .05% decrement in mean arterial blood pressure (99 +/- 3.3 mm Hg vs 94 +/- 3.6 mm Hg) (P<.05) during the cold pressor test. Pressor reactivity to cold stress did not change in the untrained group. Measures of heart rate, cardiac output, total peripheral resistance, and forearm blood flow were unaltered during conditions of the cold pressor test. We conclude that aerobic exercise attenuates the blood pressure reactivity to behavioral stress in young, adult normotensive African-American females. A lifestyle change such as exercising may play a role in reducing the risk of hypertension in African-American women.


Assuntos
População Negra , Pressão Sanguínea/fisiologia , Temperatura Baixa/efeitos adversos , Teste de Esforço , Terapia por Exercício/métodos , Hipertensão/prevenção & controle , Hipertensão/fisiopatologia , Adulto , Feminino , Frequência Cardíaca/fisiologia , Humanos , Hipertensão/diagnóstico , Hipertensão/genética , Estilo de Vida , Consumo de Oxigênio/fisiologia , Resistência Vascular/fisiologia
15.
J Cardiovasc Risk ; 3(5): 423-6, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9048256

RESUMO

OBJECTIVE: To determine whether peripheral hemodynamic differences exist in young adult normotensive African Americans and white Americans with a positive and negative parental history of hypertension. METHODS: The participants were healthy men of whom 13 were African Americans and nine white Americans with a positive parental history and 19 were African Americans and 13 white Americans with a negative parental history. Lower leg blood flows were obtained at rest and during reactive hyperemia. Lower leg minimum vascular resistance (Rmin) was computed from reactive hyperemic blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. RESULTS: Resting blood flow and mean arterial pressure were similar in all groups. A significant race x parental history interaction effect was observed for lower leg Rmin. In the white men the lower leg Rmin was significantly greater in the positive than the negative parental group (P < 0.05). Lower leg Rmin was significantly greater in African Americans than in white men without a parental histoy (P < 0.05). Mean arterial blood pressure and heart rate were similar among the groups. CONCLUSIONS: This study demonstrates that lower leg Rmin is greater in young white men with a positive parental history of hypertension than those with a negative parental history. In African Americans with either positive or negative parental histories, lower leg Rmin is not different. This finding suggests that heredity may have a greater influence in white populations than in African Americans on the structural changes in resistance vessels. The study also suggests that African Americans have an earlier structural change in the resistance vessels compared with white people, regardless of a parental history of hypertension. This suggests that factors other than heredity are of importance in changing the structure of the resistance vessels.


Assuntos
Hipertensão/etnologia , Hipertensão/genética , Resistência Vascular/fisiologia , Adulto , População Negra , Humanos , Hipertensão/fisiopatologia , Perna (Membro)/irrigação sanguínea , Masculino , Estudos Prospectivos , Fatores de Risco , Resistência Vascular/genética , População Branca
16.
Can J Appl Physiol ; 21(3): 209-17, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8792025

RESUMO

High-intensity resistance (HIR) training has been associated with muscle hypertrophy and decreased microvascular density that might produce a blood flow limitation. The effect of HIR training on lower leg maximal blood flow and minimum vascular resistance (Rmin) during reactive hyperemia were investigated in 7 healthy males. The gastrocnemius-soleus muscles of one leg were trained using maximal isokinetic concentric contractions for 4 weeks; the nontrained leg was the control. Lower leg blood flow was measured by venous occlusion plethysmography. Lower leg muscle volume was determined using magnetic resonance imaging. Peak isokinetic torque increased in both the trained (T) and nontrained (NT) legs (p < .05). Lower leg muscle volume increased by 2% in the T leg only (p < .05). In the T leg, maximal blood flow decreased and Rmin increased (p < .05); no hemodynamic change was detected in the NT leg. It is concluded that HIR training of the calf muscles is associated with a decrease in hyperemia-induced blood flow; thereby, indicating a blood flow limitation to the calf muscles.


Assuntos
Perna (Membro)/fisiologia , Músculo Esquelético/fisiologia , Adaptação Fisiológica , Adulto , Hemodinâmica , Humanos , Hiperemia/fisiopatologia , Hipertrofia , Perna (Membro)/irrigação sanguínea , Imageamento por Ressonância Magnética , Masculino , Microcirculação , Contração Muscular , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/patologia , Pletismografia , Fluxo Sanguíneo Regional , Torque , Resistência Vascular
17.
Cognition ; 59(3): 247-74, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8706378

RESUMO

The essentialist approach to word meaning has been used to undermine the fundamental assumptions of the cognitive psychology of concepts. Essentialism assumes that a word refers to a natural kind category in virtue of category members possessing essential properties. In support of this thesis, Kripke and Putnam deploy various intuitions concerning word use under circumstances in which discoveries about natural kinds are made. Although some studies employing counterfactual discoveries and related transformations appear to vindicate essentialism, we argue that the intuitions have not been investigated exhaustively. In particular, we argue that discoveries concerning the essential properties of whole categories (rather than simply of particular category members) are critical to the essentialist intuitions. The studies reported here examine such discovery contexts, and demonstrate that words and concepts are not used in accordance with essentialism. The results are, however, consistent with "representational change" views of concepts, which are broadly Fregean in their motivation. We conclude that since essentialism is not vindicated by ordinary word use, it fails to undermine the cognitive psychology of concepts.


Assuntos
Formação de Conceito , Filosofia , Psicolinguística , Semântica , Adulto , Feminino , Humanos , Masculino
18.
19.
Foot Ankle Int ; 16(5): 277-84, 1995 May.
Artigo em Inglês | MEDLINE | ID: mdl-7633584

RESUMO

Measurements of first ray mobility, pressure, and other variables were made on 19 diabetic patients with a history of ulceration at the first metatarsal head, 20 diabetic patients with a history of ulceration at other locations of the forefoot, 19 matched diabetic controls, and 19 matched nondiabetic controls. Patients with a history of first metatarsal head ulceration had significantly less first ray mobility and significantly higher pressure at the first metatarsal head compared with the other groups. Regression analysis found a moderate inverse linear relationship between first ray dorsiflexion and peak pressure at the first metatarsal head (R2 = 0.46, P < .0001). Results showed that sensory loss, duration of diabetes, and limited range of motion at the hip, ankle, and foot were related to ulcerations at all forefoot locations, Limited first ray mobility and high pressure at the first metatarsal head were related to ulcerations only at the first metatarsal head location.


Assuntos
Pé Diabético/fisiopatologia , Metatarso , Amplitude de Movimento Articular , Dedos do Pé/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pressão , Fatores de Risco
20.
J Biol Chem ; 269(13): 9721-8, 1994 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-8144563

RESUMO

Rates of radiolytic inactivation of bacteria suspended in N2O-saturated solutions were dramatically increased over normal background levels when the media contained chloride or bicarbonate ions. The bacteria could be protected from this enhanced toxicity by the addition of free radical scavengers (ethanol, ascorbate, hydrogen peroxide, mannitol, glucose, EDTA, picolinic acid), indicating that the lethal reactions were extracellular in origin. Prior irradiation of chloride-containing solutions led to formation of hypochlorous acid, which was identified by detection of ring-chlorinated products when reacted with fluorescein. Prolonged irradiation of other solutions did not lead to accumulation of bactericidal agents; however, irradiation of bicarbonate-containing solutions in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) led to formation of the EPR-detectable DMPO.CO3- adduct. The results are interpreted in terms of formation of secondary radicals, among which the carbonate and chlorine radicals are uniquely toxic to bacteria. From rate comparisons of the solution components, it was concluded that the reactions involving chloride ion are unlikely to be expressed in biological environments, but that the CO3- radical could be an important intermediary oxidant in peroxide-inflicted cellular damage, particularly in spatially confined environments such as the leukocyte phagosome.


Assuntos
Antibacterianos/toxicidade , Escherichia coli/efeitos dos fármacos , Radical Hidroxila/toxicidade , Lactococcus lactis/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Ácido Ascórbico/farmacologia , Sinergismo Farmacológico , Ácido Edético/farmacologia , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/efeitos da radiação , Etanol/farmacologia , Sequestradores de Radicais Livres , Raios gama , Glucose/farmacologia , Peróxido de Hidrogênio/farmacologia , Cinética , Lactococcus lactis/crescimento & desenvolvimento , Lactococcus lactis/efeitos da radiação , Luz , Manitol/farmacologia , Modelos Biológicos , Ácidos Picolínicos/farmacologia , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/efeitos da radiação
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