RESUMO

Foram avaliados os efeitos da radiação gama nas doses de 1,5 e 3,0kGy, em peitos de frango embalados em embalagem convencional e a vácuo. As amostras embaladas foram submetidas à irradiação e estocadas sob refrigeração (4ºC) por 30 dias. A radiação mostrou-se eficiente na redução de mesófilos aeróbios estritos e facultativos viáveis, coliformes totais e termotolerantes, com destaque para Salmonella spp. Os bolores e leveduras mostraram-se bastante resistentes à radiação. Os resultados sugerem que a dose de 3,0kGy pode ser utilizada no controle da microbiota do peito de frango armazenado sob refrigeração, sendo uma alternativa para o aumento da vida de prateleira por até 10 dias, ao garantir a segurança do consumidor pela eliminação de possíveis patógenos.

The effects of gamma radiation doses of 1.5 and 3.0kGy on chicken breasts packed under conventional or vacuum atmosphere were evaluated. The packed samples were subjected to irradiation and stored under refrigeration (4ºC) for 30 days. The radiation was efficient in reducing strict and facultative aerobic mesophiles, total and fecal coliforms, and mainly Salmonella spp. The molds and yeasts were very resistant to radiation. The results suggest that gamma radiation at 3.0kGy can be used to control the microbiota in chicken breast stored under refrigeration, as an alternative to extend the shelf-life for more than ten days and ensure the food safety by eliminating potential pathogens.

Assuntos

RESUMO

Foram avaliados os efeitos da radiação gama nas doses de 1,5 e 3,0kGy, em peitos de frango embalados em embalagem convencional e a vácuo. As amostras embaladas foram submetidas à irradiação e estocadas sob refrigeração (4ºC) por 30 dias. A radiação mostrou-se eficiente na redução de mesófilos aeróbios estritos e facultativos viáveis, coliformes totais e termotolerantes, com destaque para Salmonella spp. Os bolores e leveduras mostraram-se bastante resistentes à radiação. Os resultados sugerem que a dose de 3,0kGy pode ser utilizada no controle da microbiota do peito de frango armazenado sob refrigeração, sendo uma alternativa para o aumento da vida de prateleira por até 10 dias, ao garantir a segurança do consumidor pela eliminação de possíveis patógenos.(AU)

The effects of gamma radiation doses of 1.5 and 3.0kGy on chicken breasts packed under conventional or vacuum atmosphere were evaluated. The packed samples were subjected to irradiation and stored under refrigeration (4ºC) for 30 days. The radiation was efficient in reducing strict and facultative aerobic mesophiles, total and fecal coliforms, and mainly Salmonella spp. The molds and yeasts were very resistant to radiation. The results suggest that gamma radiation at 3.0kGy can be used to control the microbiota in chicken breast stored under refrigeration, as an alternative to extend the shelf-life for more than ten days and ensure the food safety by eliminating potential pathogens.(AU)

Assuntos

RESUMO

UNLABELLED: In 1987, Costa Rica implemented a national salt fluoridation programme using sodium fluoride (225-275 mg F/kg). OBJECTIVE: To evaluate the prevalence and severity of enamel fluorosis (EF) in Costa Rican schoolchildren as part of the biological monitoring of the salt fluoridation programme. BASIC RESEARCH DESIGN: In 1999, eight calibrated examiners (interexaminer Kappa = 0.73) recorded EF in the maxillary anterior teeth and first bicuspids (FDI's teeth 14 to 24) using Dean's Index and artificial light without drying. The multistrata probability sample included 12 and 15-year-old schoolchildren (n = 2,499), representing seven regions of the country. Data were analyzed in SAS and SUDAAN to account for sampling design. SETTING: Costa Rican schoolchildren. The 12-year-old cohort was born when salt fluoridation started. PARTICIPANTS: 3,758 children in selected age groups. MAIN OUTCOME MEASURES: Dean's index was calculated for cuspid to cuspid (teeth 13 to 23) and premolar to premolar (teeth 14 to 24). RESULTS: Prevalence of EF (very mild or higher) at age 12 years was 17% for teeth 13 to 23 and 32% when teeth 14 and 24 were included. At age 15 years, the prevalence was 12% for teeth 13 to 23 and 25% when teeth 14 and 24 were included. Large regional differences were observed: from 10% to 76% among 12-year-old children and from 6% to 50% among 15-year-old children. CONCLUSIONS: In the aggregate, EF prevalence is within the range expected for a salt fluoridation programme, but regions with higher severity need further investigation on additional sources of fluoride including environmental sources. Prevalence figures were higher in the cohort born at time of fluoridation.

Assuntos

RESUMO

Serine-proteases are involved in vital processes in virtually all species. They are important targets for researchers studying the relationships between protein structure and activity, for the rational design of new pharmaceuticals. Trypsin was used as a model to assess a possible differential contribution of hydration water to the binding of two synthetic inhibitors. Thermodynamic parameters for the association of bovine beta-trypsin (homogeneous material, observed 23,294.4 +/- 0.2 Da, theoretical 23,292.5 Da) with the inhibitors benzamidine and berenil at pH 8.0, 25 degrees C and with 25 mM CaCl2, were determined using isothermal titration calorimetry and the osmotic stress method. The association constant for berenil was about 12 times higher compared to the one for benzamidine (binding constants are K = 596,599 +/- 25,057 and 49,513 +/- 2,732 M(-1), respectively; the number of binding sites is the same for both ligands, N = 0.99 +/- 0.05). Apparently the driving force responsible for this large difference of affinity is not due to hydrophobic interactions because the variation in heat capacity (DeltaCp), a characteristic signature of these interactions, was similar in both systems tested (-464.7 +/- 23.9 and -477.1 +/- 86.8 J K(-1) mol(-1) for berenil and benzamidine, respectively). The results also indicated that the enzyme has a net gain of about 21 water molecules regardless of the inhibitor tested. It was shown that the difference in affinity could be due to a larger number of interactions between berenil and the enzyme based on computational modeling. The data support the view that pharmaceuticals derived from benzamidine that enable hydrogen bond formation outside the catalytic binding pocket of beta-trypsin may result in more effective inhibitors.

Assuntos

RESUMO

Serine-proteases are involved in vital processes in virtually all species. They are important targets for researchers studying the relationships between protein structure and activity, for the rational design of new pharmaceuticals. Trypsin was used as a model to assess a possible differential contribution of hydration water to the binding of two synthetic inhibitors. Thermodynamic parameters for the association of bovine ß-trypsin (homogeneous material, observed 23,294.4 ± 0.2 Da, theoretical 23,292.5 Da) with the inhibitors benzamidine and berenil at pH 8.0, 25°C and with 25 mM CaCl2, were determined using isothermal titration calorimetry and the osmotic stress method. The association constant for berenil was about 12 times higher compared to the one for benzamidine (binding constants are K = 596,599 ± 25,057 and 49,513 ± 2,732 M-1, respectively; the number of binding sites is the same for both ligands, N = 0.99 ± 0.05). Apparently the driving force responsible for this large difference of affinity is not due to hydrophobic interactions because the variation in heat capacity (DCp), a characteristic signature of these interactions, was similar in both systems tested (-464.7 ± 23.9 and -477.1 ± 86.8 J K-1 mol-1 for berenil and benzamidine, respectively). The results also indicated that the enzyme has a net gain of about 21 water molecules regardless of the inhibitor tested. It was shown that the difference in affinity could be due to a larger number of interactions between berenil and the enzyme based on computational modeling. The data support the view that pharmaceuticals derived from benzamidine that enable hydrogen bond formation outside the catalytic binding pocket of ß-trypsin may result in more effective inhibitors.

Assuntos

RESUMO

Foram utilizados para esta revisão trabalhos que estudassem o congelamento do sêmen canino. Os resultados na maioria das pesquisas constataram que o sêmen canino é de baixa qualidade. Publicações relatam obtenção de melhores resultados utilizando o tris-frutose-ácido cítrico como diluidor, glicerol como crioprotetor, método de congelamento lento e descongelamento em água a 37º C.

Assuntos

RESUMO

We describe the purification of a cysteine proteinase from latex of Carica candamarcensis, hereby designated CC23. The enzyme has been purified by ion-exchange chromatography and behaves electrophoretically as a monomer of M(r) 23,000 and optimal pH of 8.0. It displays a basic isoelectric point, has one cysteine residue in the active site by titration with E-64, confirmed by DNA sequencing, and responds to proteinase inhibitors as a classic cysteine proteinase. The K(m) and k(cat)/K(m) for CC23 using BAPNA were respectively 14.7 +/- 1.8 x 10(-4) M and 1.3 x 10(3) M(-1) s(-1). Therefore, the catalytic efficiency of CC23 is sixfold higher than that of CC-I, another proteinase from the same plant. DNA primers were designed to amplify by PCR a genomic sequence related to this enzyme. An 895-bp DNA fragment was cloned and sequenced. It shows strong homology with chymopapain isoform IV from C. papaya. The translated sequence is similar to that of chymopapain isoform II (73%) and CC-III (77%) from C. candamarcensis.

Assuntos

RESUMO

We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of 60Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58%) was seen 24 h after irradiation, followed by a decrease at 48 h (11%). At the high radiation dose (20 Gy) a low protective effect was also seen (35%). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 (N-(2-mercaptoethyl)-1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.

Assuntos

RESUMO

We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of (60)Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58 per cent) was seen 24 h after irradiation, followed by a decrease at 48 h (11 per cent). At the high radiation dose (20 Gy) a low protective effect was also seen (35 per cent). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 N-(2-mercaptoethyl) - 1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.

Assuntos

RESUMO

Report of an unusual case of myopathy in an HIV infected patient, responsive only to the immunosuppressor drug methotrexate. The patient was a 39 year old homosexual male with no past history of HIV-related manifestations. One month prior to admission he noticed that his left thigh was swollen and painful. Two weeks later both arms became enlarged and tender. A few days before admission he noticed intermittent fever and progressive dyspnea. Upon admission, oral thrush, dyspnea and global enlargement of both arms was noted. There was no articular involvement. Fiberoptic bronchoscopy revealed Pneumocystis carinii pneumonia (PCP). Serology for HIV was positive. Tests for antinuclear antibodies were negative. Serum CPK level was 1019 IU. Capillaroscopy was compatible with vasculitis. Muscle biopsy revealed multifocal myonecrosis. PCP was successfully treated with standard doses of TMP/SMZ. Although indomethacin, prednisone and dexamethasone were administered in succession, there was relentless progression of myopathy and persistence of fever. Six days after administration of methotrexate, the patient defervesced, volume of arms and legs diminished. CPK levels returned to normal after a second course of methotrexate. Upon reduction of the dose thigh enlargement recrudesced. The patient remained asymptomatic on weekly doses of methotrexate. He died five months later of acute respiratory failure.

PIP: Myopathy may be associated with the syndrome of seroconversion in individuals infected by the human immunodeficiency virus (HIV) or may represent the initial symptom of AIDS. In 1990, 39-year old white, single homosexual who was admitted 1 month prior had experienced an episode of edema and pain in the left thigh that faded with the use of nonhormonal antiinflammatory drugs. 15 days later both forearms became enlarged accompanied by pain and erythema. Erythromycin and cefalexine were used without success. Intermittent fever started to appear before admission accompanied by dyspnea when straining. Examination showed tachypnea, oral candidiasis, and enlargement of both upper arms with pain and local erythema without articular involvement. Neurological examination revealed hypotonia and generalized hyperreflexia with intact muscle strength. Serology was positive for HIV, rheumatic activity tests were negative, and muscle biopsy indicated multifocal myonecrosis. Creatinine phosphokinase was 1019 IU (decrease to 44 IU after treatment), aldolase was 19 IU (decrease to 5.6 IU), and glutamic-pyruvic transminase was 50 IU (decrease to 22 IU). Radiography of the thorax indicated interstitial infiltration. Fiberoptic bronchoscopy indicated Pneumocystis carinii pneumonia. Sulfamethoxazole and trimetropim treatment cured the dyspnea and hypoxemia, but the enlargement of both arms progressed. Capillaroscopy indicated vasculitis that was treated without success with indomethacin (150 mg/day), for 7 days; prednisone (40-80 mg/day) for 10 days; and dexamethasone (280 mg/day) for 2 days. 6 days after methotrexate (50 mg/dose/week) treatment the fever disappeared and the enlargement in the extremities receded, but a lower dose of 7.5 mg caused the return of fever and edema in the right thigh. The myopathy remained asymptomatic for 5 months with a weekly dose of 15 mg of methotrexate.

Assuntos

RESUMO

Foram testadas 95 estirpes de Bacillus e 10 de Staphylococcus aureus quanto a sensibilidade face a 14 fagos recem isolados de B. subtilis e 16 de B. pumilus.Todas as estirpes de S. aureus e 65 de Bacillus mostraram-se resistentes a lise por quaisquer dos fagos de Bacillus.Entre as estirpes de referencia, apenas aquelas de B.subtilis e B. pumilus foram lisadas por fagos de ambos os hospedeiros. As estirpes sensiveis recentemente isoladas foram identificadas como B. subtilis e B. pumilus Todos os fagos de B. subtilis eram especies especificos; no entanto, a maioria dos fagos de B. pumilus lisava ambas as especies. Tais dados confirmam a proximidade taxonomica destas especies

Assuntos