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A 7-year-old neutered Maltese dog weighing 5.1 kg was presented, with a tibial plateau-leveling osteotomy (TPLO) on the right hindlimb 42 days prior. The patient's right hind limb showed lameness, intermittent limping, and atrophy, and the patient had not experienced rehabilitation since TPLO surgery. The patient showed a pain reaction at the end of the stifle extension, and an increased body temperature was identified on the medial side of the right hindlimb when compared with the left hindlimb using a digital thermal imaging device. In addition, a type of lameness, only partial weight bearing in the right hindlimb, was also identified during the gait analysis. The pain was relieved by applying a cold pack and transcutaneous electrical nerve stimulation, and the patient's weak muscles were strengthened through treadmill exercises. In this study, physical therapy and rehabilitation exercises controlled pain and induced rapid recovery, indicating that rehabilitative intervention is required after TPLO surgery.
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A two-year-old male Pomeranian dog was presented to a veterinary hospital due to the side effects of a surgical correction for patellar luxation. Stifle joint arthrodesis (SJA) was performed on the patient's right leg using autologous bone-grafting techniques. The right femur and tibial joint were angled 120-130°, and an SJA plate was fixed on the front of the two bones. After performing joint fusion of the right limb, medial-patellar-luxation-(MPL)-corrective surgery was performed to cut the tibial tuberosity on the left leg, and the fixing force was increased using the figure-of-eight-tension-band-wiring technique. Results were recorded regarding the dog's ability to walk and trot in the right hind limb; these results were evaluated for 27 days after surgery. It was difficult for the patient to walk because weight-bearing had not been carried out for 3 days after the surgery; short strides and partial weight bearing were possible 5 to 7 days after surgery. After 10 days, the patient was able to move while bearing weight with a slight disruption. With regard to trotting, the patient showed intermittent normal steps 5 to 7 days after surgery, but the disruption continued. After 14 days, trotting was possible, and it was observed that movement could be maintained during everyday activities.
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Artificial intelligence (AI) is an emerging technology that is revolutionizing the discovery of new materials. One key application of AI is virtual screening of chemical libraries, which enables the accelerated discovery of materials with desired properties. In this study, we developed computational models to predict the dispersancy efficiency of oil and lubricant additives, a critical property in their design that can be estimated through a quantity named blotter spot. We propose a comprehensive approach that combines machine learning techniques with visual analytics strategies in an interactive tool that supports domain experts' decision-making. We evaluated the proposed models quantitatively and illustrated their benefits through a case study. Specifically, we analyzed a series of virtual polyisobutylene succinimide (PIBSI) molecules derived from a known reference substrate. Our best-performing probabilistic model was Bayesian Additive Regression Trees (BART), which achieved a mean absolute error of 5.50±0.34 and a root mean square error of 7.56±0.47, as estimated through 5-fold cross-validation. To facilitate future research, we have made the dataset, including the potential dispersants used for modeling, publicly available. Our approach can help accelerate the discovery of new oil and lubricant additives, and our interactive tool can aid domain experts in making informed decisions based on blotter spot and other key properties.
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The exceptional versatility of sulfones has been extensively exploited in organic synthesis across several decades. Since the first demonstration in 2005 that sulfones can participate in Pd-catalysed Suzuki-Miyaura type reactions, tremendous advances in catalytic desulfitative functionalizations have opened a new area of research with burgeoning activity in recent years. This emerging field is displaying sulfone derivatives as a new class of substrates enabling catalytic C-C and C-X bond construction. In this review, we will discuss new facets of sulfone reactivity toward further expanding the flexibility of C-S bonds, with an emphasis on key mechanistic features. The inherent challenges confronting the development of these strategies will be presented, along with the potential application of this chemistry for the synthesis of natural products. Taken together, this knowledge should stimulate impactful improvements on the use of sulfones in catalytic desulfitative C-C and C-X bond formation. A main goal of this article is to bring this technology to the mainstream catalysis practice and to serve as inspiration for new perspectives in catalytic transformations.
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Metales , Sulfonas , CatálisisRESUMEN
A method for the annulation of amines and carboxylic acids to form pharmaceutically relevant azaheterocycles via organophosphorus PIII/PV redox catalysis is reported. The method employs a phosphetane catalyst together with a mild bromenium oxidant and terminal hydrosilane reductant to drive successive C-N and C-C bond-forming dehydration events via the serial action of a catalytic bromophosphonium intermediate. These results demonstrate the capacity of PIII/PV redox catalysis to enable iterative redox-neutral transformations in complement to the common reductive driving force of the PIII/PV couple.
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Aminas/química , Ácidos Carboxílicos/química , Compuestos Heterocíclicos/síntesis química , Carbono/química , Catálisis , Ciclización , Nitrógeno/química , Oxidación-ReducciónRESUMEN
A method for electrophilic sulfenylation by organophosphorus-catalyzed deoxygenative O-atom transfer from sulfonyl chlorides is reported. This C-S bond-forming reaction is catalyzed by a readily available small-ring phosphine (phosphetane) in conjunction with a hydrosilane terminal reductant to afford a general entry to sulfenyl electrophiles, including valuable trifluoromethyl, perfluoroalkyl, and heteroaryl derivatives that are otherwise difficult to access. Mechanistic investigations indicate that the twofold deoxygenation of the sulfonyl substrate proceeds by the intervention of an off-cycle resting state thiophosphonium ion. The catalytic method represents an operationally simple protocol using a stable phosphine oxide as a precatalyst and exhibits broad functional-group tolerance.
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Hidrocarburos Fluorados/química , Compuestos Organofosforados/química , Oxígeno/química , Ácidos Sulfénicos/química , Ácidos Sulfínicos/química , Catálisis , Estructura Molecular , Oxidación-ReducciónRESUMEN
This study aimed to investigate the associations between peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) gene Gly482Ser polymorphism (rs8192678) and parameters of insulin resistance in a sample of Korean children. A total of 286 children aged 10 to 12 years old were recruited from local elementary schools. Measured variables included body fat, blood pressures, blood lipids, glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and accelerometer-based physical activity (PA). Significant differences in percentage body fat (P = .016), insulin (P = .013), and HOMA-IR (P = .007) were found according to Gly482Ser genotype, with no significant genotype differences in the other measured variables. The genotype-specific differences in insulin (P = .136) and HOMA-IR (P = .067) were significantly attenuated when adjusted for age, sex, Tanner stage, body fat, and PA. The findings of the study suggest that the genetic effects of the PGC-1α genotypes on parameters of insulin resistance might be modulated by lifestyle factors, including PA and body fatness.
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Resistencia a la Insulina/genética , Síndrome Metabólico/genética , Factores de Transcripción/genética , Adiposidad , Glucemia , Presión Sanguínea , Niño , Femenino , Genotipo , Humanos , Lípidos/sangre , Masculino , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Polimorfismo Genético , República de Corea/epidemiologíaRESUMEN
PURPOSE: Severe hyperkalemia leads to significant morbidity and mortality if it is not immediately recognized and treated. The concentration of potassium (Kâº) in the serum increases along with deteriorating renal function. The use of point-of-care K⺠(POC-Kâº) in chronic kidney disease (CKD) could reduce the time for an accurate diagnosis and treatment, saving lives. We hypothesized that POC-K⺠would accurately report K⺠serum level without significant differences compared to reference testing, regardless of the renal function of the patient. MATERIALS AND METHODS: The retrospective study was performed between January 2008 and September 2011 at an urban hospital in Seoul. The screening program using POC was conducted as a critical pathway for rapid evaluation and treatment of hyperkalemia since 2008. When a patient with CKD had at least one warning symptom or sign of hyperkalemia, both POC-K⺠and routine laboratory tests were simultaneously ordered. The reliability of the two assays for serum-creatinine was assessed by intra-class correlation coefficient (ICC) analysis using absolute agreement of two-way mixed model. RESULTS: High levels of reliability were found between POC and the laboratory reference tests for K⺠(ICC=0.913, 95% CI 0.903-0.922) and between two tests for K⺠according to changes in the serum-creatinine levels in CKD patients. CONCLUSION: The results of POC-K⺠correlate well with values obtained from reference laboratory tests and coincide with changes in serum-creatinine of patients with CKD.
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Hiperpotasemia/diagnóstico , Potasio/sangre , Insuficiencia Renal Crónica/sangre , Análisis Químico de la Sangre/métodos , Servicio de Urgencia en Hospital , Humanos , Sistemas de Atención de Punto , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Admission on weekends and off-hours has been associated with poor outcomes and mortality from acute stroke. The purpose of this study was to investigate whether an organized clinical pathway (CP) for ischemic stroke can effectively reduce the time from arrival to evaluation and treatment in the emergency department (ED) and improve outcomes, regardless of the time from arrival in the ED. METHODS: We conducted a retrospective analysis of all consecutive patients included in the prospective registry database in the Brain Salvage through Emergency Stroke Therapy program, which uses the computerized physician order entry (CPOE) system. Patients were classified based on their time of arrival in the ED: group 1, normal working hours on weekdays; group 2, off-hours on weekdays; group 3, normal working hours on weekends; and group 4, off-hours on weekends. Clinical outcomes were categorized according to 30 days in-hospital mortality, in-hospital mortality, and the modified Rankin score during a single length of stay (LOS). RESULTS: No time intervals differed significantly among the 4 patient groups who received intravenous administration of tissue plasminogen activator (IV-tPA). Use of IV-tPA (P = .5110) was not affected by arrival in the ED on off-days or weekends. The overall mortality rate was 3.9%, and the median LOS was 7 days (Interquartile range (IQR), 5-10). By Kaplan-Meier analysis, the cumulative probability of mortality and survival did not differ significantly among the 4 groups over 30 days (P = .1557). CONCLUSION: An organized CP, based on CPOE, for ischemic stroke can effectively attenuate disparities in the time interval between ED arrival to evaluation and treatment regardless of ED arrival time. This pathway may also help to eliminate off-hour and weekend effects on outcomes from ischemic stroke.
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Vías Clínicas , Servicio de Urgencia en Hospital/organización & administración , Sistemas de Entrada de Órdenes Médicas , Accidente Cerebrovascular/terapia , Administración Intravenosa , Adulto , Anciano , Anciano de 80 o más Años , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Fibrinolíticos/administración & dosificación , Fibrinolíticos/uso terapéutico , Mortalidad Hospitalaria , Humanos , Estimación de Kaplan-Meier , Tiempo de Internación , Masculino , Persona de Mediana Edad , Evaluación del Resultado de la Atención al Paciente , Sistema de Registros/estadística & datos numéricos , Estudios Retrospectivos , Accidente Cerebrovascular/tratamiento farmacológico , Factores de Tiempo , Activador de Tejido Plasminógeno/administración & dosificación , Activador de Tejido Plasminógeno/uso terapéutico , Adulto JovenRESUMEN
PURPOSE: This study examined the relations of serum vitamin D levels to body fatness, cardiorespiratory fitness (CRF), and metabolic risk factors in young adults in Korea. METHODS: Between 2007 and 2009, 799 young men completed a health examination. Body fatness, CRF based on a maximal treadmill exercise test, and measurements of metabolic risk factors were measured in study participants. Participants were classified by serum vitamin D levels as deficient (<12.5 ng·mL), insufficient (≥12.5 to <20 ng·mL), and sufficient (>20 ng·mL) and by CRF as unfit (lowest 20%) and fit (remaining 80%) based on age-standardized distribution of VËO2max values in this study population. Body fatness, CRF, and metabolic risk factors were evaluated according to serum vitamin D classification. A clustered metabolic risk score was computed by summing standardized scores for waist circumference, resting blood pressures, triacylglycerols, the inverse of high-density lipoprotein cholesterol, glucose, and insulin. RESULTS: Linear decreases in body fatness and metabolic risk factors were observed, as was a linear increase for CRF across incremental vitamin D categories. A linear decrease was found in the clustered metabolic risk score across incremental vitamin D categories. Compared to the fit group (reference), the unfit group had significantly higher risks for serum vitamin D inadequacy before and after adjusting for age, smoking, and body fatness parameters. CONCLUSIONS: The findings of the study suggest that increasing vitamin D intake, eating a healthy diet, and getting enough outdoor physical activity should be promoted as nonpharmacologic means to improve CRF and prevent a clustering of metabolic risk factors in young adults.
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Síndrome Metabólico/etiología , Deficiencia de Vitamina D/complicaciones , Vitamina D/sangre , Adulto , Composición Corporal/fisiología , Estudios Transversales , Humanos , Masculino , Oportunidad Relativa , Consumo de Oxígeno , Examen Físico , Aptitud Física/fisiología , República de Corea , Factores de Riesgo , Vitamina D/metabolismo , Adulto JovenRESUMEN
Substantia nigra and striatum are vulnerable to hypoxic ischemia brain injury. Physical exercise promotes cell survival and functional recovery after brain injury. However, the effects of treadmill exercise on nigro-striatal dopaminergic neuronal loss induced by hypoxic ischemia brain injury in neonatal stage are largely unknown. We determined the effects of treadmill exercise on survival of dopamine neurons in the substantia nigra and dopaminergic fibers in the striatum after hypoxic ischemia brain injury. On postnatal 7 day, left common carotid artery of the neonatal rats ligated for two hours and the neonatal rats were exposed to hypoxia conditions for one hour. The rat pups in the exercise groups were forced to run on a motorized treadmill for 30 min once a day for 12 weeks, starting 22 days after induction of hypoxic ischemia brain injury. Spatial learning ability in rat pups was determined by Morris water maze test after last treadmill exercise. The viability of dopamine neurons in the substantia nigra and dopamine fibers in the striatum were analyzed using immunohistochemistry. In this study, hypoxic ischemia injury caused loss of dopamine neurons in the substantia nigra and dopaminergic fibers in the striatum. Induction of hypoxic ischemia deteriorated spatial learning ability. Treadmill exercise ameliorated nigro-striatal dopaminergic neuronal loss, resulting in the improvement of spatial learning ability. The present study suggests the possibility that treadmill exercise in early adolescent period may provide a useful strategy for the recovery after neonatal hypoxic ischemia brain injury.
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PURPOSE: Prenatal environmental conditions affect the development of the fetus. In the present study, we investigated the effects of exposure to music and noise during pregnancy on neurogenesis and thickness in the motor and somatosensory cortex of rat pups. METHODS: The pregnant rats in the music-applied group were exposed to 65 dB of comfortable music for 1 hour, once per day, from the 15th day of pregnancy until delivery. The pregnant rats in the noise-applied group were exposed to 95 dB of sound from a supersonic sound machine for 1 hour, once per day, from the 15th day of pregnancy until delivery. After birth, the offspring were left undisturbed together with their mother. The rat pups were sacrificed at 21 days after birth. RESULTS: Exposure to music during pregnancy increased neurogenesis in the motor and somatosensory cortex of rat pups. In contrast, rat pups exposed to noise during pregnancy showed decreased neurogenesis and thickness in the motor and somatosensory cortex. CONCLUSIONS: Our study suggests that music and noise during the developmental period are important factors influencing brain development and urogenital disorders.
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BACKGROUND: Despite the usefulness of the Cincinnati Prehospital Stroke Scale (CPSS) for rapid recognition of acute stroke, its ability to assess stroke severity is unclear. We investigated the usefulness of CPSS for assessment of stroke severity by comparing CPSS and National Institutes of Health Stroke Scale (NIHSS) scores in patients who were candidates for thrombolytic therapy at hospital admission within 6 hours of symptom onset. METHODS: We conducted a retrospective analysis of a prospective registry database of consecutive patients included in the brain salvage through emergency stroke therapy program. In the emergency department, CPSS score was determined by emergency medical technicians. A CPSS cut-off score was estimated for candidates of thrombolytic therapy by comparing CPSS and NIHSS scores of patients who actually received thrombolytic therapy. Clinical outcomes were compared among patients with scores near the cut-off. Independent predictors of outcome were evaluated by multivariate logistic regression analysis. RESULTS: Strong correlations were observed between CPSS and NIHSS scores within 3 hours (R = 0.778) and 6 hours (R = 0.769) of symptom onset. The optimal cut-off score was 2 for CPSS was associated with actual usage of intravenous tissue plasminogen activator (odds ratio [OR] 34.455; 95% confidence interval [CI] 7.924-149.817, P < .0001) and actual usage of thrombolytic therapy overall (intravenous tissue plasminogen activator or intra-arterial urokinase) (OR 36.310; 95% CI 10.826-121.782, P < .0001). CONCLUSION: The CPSS is an effective prehospital stroke scale for the determination of stroke severity and identification of candidates for thrombolytic therapy.
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Isquemia Encefálica/tratamiento farmacológico , Fibrinolíticos/uso terapéutico , Selección de Paciente , Accidente Cerebrovascular/tratamiento farmacológico , Terapia Trombolítica/métodos , Activador de Tejido Plasminógeno/uso terapéutico , Activador de Plasminógeno de Tipo Uroquinasa/uso terapéutico , Anciano , Estudios de Cohortes , Servicios Médicos de Urgencia/métodos , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Resultado del TratamientoRESUMEN
Thyroid hormones play a crucial role in new neuron production and maturation during brain development. Physical exercise is known to promote cell survival and functional recovery after brain injuries. In the present study, we investigated the effects of treadmill exercise on short-term memory, spatial learning ability, neurogenesis, and apoptosis in hypothyroidism rat pups. On the 14th perinatal day, the pregnant rats were divided into two groups: the maternal control group and the maternal methimazole (MMI)-treated group. For the induction of hypothyroidism in rat pups, MMI was added to the drinking water (0.02%, wt/vol), from the 14th prenatal day to the 49th postnatal day. After delivery, the male rat pups born from the maternal control group were assigned into the control group and the control and exercise group. The rat pups born from the maternal MMI-treated group were divided into the hypothyroidism-induction group and the hypothyroidism-induction and treadmill exercise group. The rat pups in the exercise groups were forced to run on a motorized treadmill for 30min once a day, starting on the 22nd postnatal day for 4 weeks. Induction of hypothyroidism during the fetal and early postnatal period showed suppression of neurogenesis and enhancement of apoptosis in the hippocampus. Short-term memory and spatial learning ability were deteriorated in the hypothyroidism rat pups. Treadmill exercise during the postnatal period increased neurogenesis and inhibited apoptosis, and resulted in the improvement of short-term memory and spatial learning ability in the hypothyroidism rat pups.
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Apoptosis/fisiología , Hipocampo/fisiología , Hipotiroidismo/fisiopatología , Neurogénesis/fisiología , Condicionamiento Físico Animal/fisiología , Animales , Femenino , Hipotiroidismo/inducido químicamente , Masculino , Aprendizaje por Laberinto/fisiología , Metimazol , Ratas , Ratas Sprague-Dawley , Tiroxina/sangre , Triyodotironina/sangreRESUMEN
PURPOSE: The purpose of this study was to investigate the relationship of serum vitamin D levels with lifestyle factors, including body fatness and physical activity (PA) parameters, and the clustering of metabolic risk factors in the Korean pediatric population. METHODS: Serum 25-hydroxyvitamin D levels, accelerometer-based PA, and body fatness and metabolic syndrome parameters were assessed in a sample of children of Korean descent (N = 310). Correlation and multivariate linear regression were used to explore the relationships among serum vitamin D levels, lifestyle factors, and the clustering of metabolic risk factors in the study sample. RESULTS: Serum vitamin D levels were negatively associated with body fatness parameters, including body mass index, percent body fat, and waist circumference, but positively associated with accelerometer-based PA including low, moderate, and vigorous levels. In addition, serum vitamin D levels were inversely related to total cholesterol, triglycerides, fasting glucose, and insulin. A stepwise linear regression model showed that both low serum vitamin D levels and decreased vigorous PA were independent predictors for individual variation in the clustering of metabolic risk factors in this study sample. CONCLUSION: The results of this study suggest that an increase in vigorous PA and vitamin D intake should be two major targets of public health inventions against the clustering of metabolic risk factors in the Korean pediatric population.
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Adiposidad , Síndrome Metabólico/etiología , Actividad Motora , Deficiencia de Vitamina D/complicaciones , Vitamina D/análogos & derivados , Acelerometría , Biomarcadores/sangre , Niño , Estudios Transversales , Dieta , Femenino , Humanos , Modelos Lineales , Masculino , Síndrome Metabólico/sangre , Síndrome Metabólico/diagnóstico , República de Corea , Factores de Riesgo , Vitamina D/sangre , Deficiencia de Vitamina D/sangre , Deficiencia de Vitamina D/diagnósticoRESUMEN
OBJECTIVE: To correlate high resolution dynamic MR features with prognostic factors in breast cancer. MATERIALS AND METHODS: One hundred and ninety-four women with invasive ductal carcinomas underwent dynamic MR imaging using T1-weighted three-dimensional fast low-angle shot (3D-FLASH) sequence within two weeks prior to surgery. Morphological and kinetic MR features were determined based on the breast imaging and reporting data system (BI-RADS) MR imaging lexicon. Histological specimens were analyzed for tumor size, axillary lymph node status, histological grade, expression of estrogen receptor (ER), expression of progesterone receptor (PR), and expression of p53, c-erbB-2, and Ki-67. Correlations between the MR features and prognostic factors were determined using the Pearson chi(2) test, linear-by-linear association, and logistic regression analysis. RESULTS: By multivariate analysis, a spiculated margin was a significant, independent predictor of a lower histological grade (p < 0.001), and lower expression of Ki-67 (p = 0.007). Rim enhancement was significant, independent predictor of a higher histological grade (p < 0.001), negative expression of ER (p = 0.001), negative expression of PR (p < 0.001) and a larger tumor size (p = 0.006). A washout curve may predict a higher level of Ki-67 (p = 0.05). Most of the parameters of the initial enhancement phase cannot predict the status of the prognostic factors. Only the enhancement ratio may predict a larger tumor size (p = 0.05). CONCLUSION: Of the BI-RADS-MR features, a spiculated margin may predict favorable prognosis, whereas rim enhancement or washout may predict unfavorable prognosis of breast cancer.
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Neoplasias de la Mama/patología , Carcinoma Ductal/patología , Imagen por Resonancia Magnética/métodos , Adulto , Anciano , Distribución de Chi-Cuadrado , Medios de Contraste , Femenino , Gadolinio DTPA , Humanos , Procesamiento de Imagen Asistido por Computador , Modelos Logísticos , Persona de Mediana Edad , Invasividad Neoplásica , Pronóstico , Estudios RetrospectivosRESUMEN
Physicochemical, binding, and antibacterial properties of chitosans prepared without and with deproteinization (DP) process (5, 10, 15, and 30 min at 15 psi/121 degrees C) were compared. Chitosan from DP 0 min had comparable nitrogen content, lower degree of deacetylation and solubility, but higher molecular weight and viscosity than chitosans from DP 5-30 min. The latter four chitosans showed differences only in molecular weight. Deproteinization treatment resulted in slightly decreased L values and increased a and b values compared with those of DP 0 min. Chitosan from DP 0 min had comparable water and fat-binding capacity (FBC) except for chitosan from DP 15 min, which had a higher FBC but lower dye-binding capacity than those of the four chitosans from DP 5-30 min. The antibacterial activities of chitosans against seven different bacteria showed that the inhibitory effects varied with the deproteinization time and the particular bacterium.
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Antibacterianos/farmacología , Quitina/análogos & derivados , Quitina/química , Proteínas/análisis , Acetilación , Animales , Braquiuros/química , Fenómenos Químicos , Química Física , Quitina/metabolismo , Quitina/farmacología , Quitosano , Peso Molecular , Nitrógeno/análisis , Solubilidad , ViscosidadRESUMEN
Antibacterial activities of six chitosans and six chitosan oligomers with different molecular weights (Mws) were examined against four gram-negative (Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Vibrio parahaemolyticus) and seven gram-positive bacteria (Listeria monocytogenes, Bacillus megaterium, B. cereus, Staphylococcus aureus, Lactobacillus plantarum, L. brevis, and L. bulgaricus). Chitosans showed higher antibacterial activities than chitosan oligomers and markedly inhibited growth of most bacteria tested although inhibitory effects differed with Mws of chitosan and the particular bacterium. Chitosan generally showed stronger bactericidal effects with gram-positive bacteria than gram-negative bacteria in the presence of 0.1% chitosan. The minimum inhibitory concentration (MIC) of chitosans ranged from 0.05% to >0.1% depending on the bacteria and Mws of chitosan. As a chitosan solvent, 1% acetic acid was effective in inhibiting the growth of most of the bacteria tested except for lactic acid bacteria that were more effectively suppressed with 1% lactic or formic acids. Antibacterial activity of chitosan was inversely affected by pH (pH 4.5-5.9 range tested), with higher activity at lower pH value.
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Antibacterianos/farmacología , Quitina/farmacología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Quitina/análogos & derivados , Quitosano , Relación Dosis-Respuesta a Droga , Bacterias Gramnegativas/crecimiento & desarrollo , Bacterias Grampositivas/crecimiento & desarrollo , Concentración de Iones de Hidrógeno , Pruebas de Sensibilidad Microbiana , Peso MolecularRESUMEN
The fate of Listeria monocytogenes was determined during kimchi fermentation and in the presence of kimchi ingredients. The lag phase was increased in tryptic soy broth at 35°C in the presence of 3% garlic, ginger, and NaCl, but not in the presence of 5% red pepper. Low levels (104 CFU/ml) of kimchi microflora did not inhibit the growth of Listeria in brain heart infusion (BHI) broth at 35°C. The growth of L. monocytogenes was inhibited in BHI broth containing a mixture of kimchi ingredients and 3% (wt/vol)NaC1 at 21°C. During kimchi fermentation at 21and 35°C, the numbers of viable cells of L. monocytogenes increased for the first 2 days of fermentation, but decreased during the next 10days. The decrease at 35°C was more rapid. L. monocytogenes was largely inactivated by kimchi ingredients and low pH, but viable cells still remained after 10 days of fermentation. These results show that kimchi is a safe product with respect to low levels of Listeria contamination which can be achieved by using ingredients of good microbiological quality.
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Inactivation by hypochlorite of Listeria monocytogenes cells adherent to stainless steel was determined. Adherent cell populations were prepared by incubating stainless steel slides with a 24 h culture of L. monocytogenes for 4 h at 21°C. Adherent microcolonies were prepared by growing L. monocytogenes on stainless steel slides submerged in a 1:15 dilution of tryptic soy broth at 21°C. The slides were then rinsed and transferred to fresh sterile broth every 2 d with a total incubation time of 8 d. Although the 4 h and 8 d adherent populations were at similar levels, 8 d adherent cells were over 100 times more resistant than the 4 h adherent cell population when exposed to 200 ppm hypochlorite for 30 s. When stainless steel slides containing adherent cells were heated at 72°C both adherent cell populations were inactivated after 1 min. Detectable numbers of L. monocytogenes remained on stainless steel slides after treatment at 65°C for 3 min when adherent 8 d cells were tested but not when adherent 4 h cells were used.