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1.
Clin Microbiol Infect ; 26(8): 1091.e1-1091.e7, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31901491

RESUMO

OBJECTIVES: Chronic pulmonary aspergillosis (CPA) is an emerging global disease with tuberculosis (TB) being the most important risk factor. Epidemiologic data on the seroprevalence of Aspergillus IgG and prevalence of CPA in different areas, especially in country with intermediate burden of TB, are lacking. METHODS: We prospectively recruited healthy volunteers, TB close contacts, active TB patients and participants with old pulmonary TB in Taiwan during 2012-2019. We measured serum Aspergillus fumigatus and niger-specific IgG levels and assessed if the participants were having CPA. RESULTS: A total of 1242 participants (including 200 healthy volunteers, 326 TB close contacts, 524 active TB patients and 192 old TB cases) were recruited. Using 27 mgA/L (milligrams of antigen-specific antibodies per liter) as cut-off level, the seropositive rate of A. fumigatus-specific IgG was 33.0% (66/200), 37.7% (123/326), 26.5% (139/524) and 43.2% (83/192) among the four groups, respectively. In multivariate logistic regression, pulmonary cavitation (OR 1.73; 95% CI 1.07-2.80), female sex (OR 1.49; 95% CI 1.14-1.95), old TB (OR 1.59; 1.05-2.42) were independent risk factors for Aspergillus IgG positivity. One (0.2%) active TB patient and four (2.1%) old TB patients developed CPA. Correlation between A. fumigatus and A. niger-specific IgG was high (Spearman correlation coefficient: 0.942). DISCUSSION: Geographic variation in Aspergillus IgG seroprevalence and CPA prevalence exists. A universal cut-off value for Aspergillus IgG may not exist. In areas and populations in which background Aspergillus IgG level is unknown, Aspergillus IgG may be better used as a test of exclusion for CPA using prespecified cut-off level.


Assuntos
Aspergillus fumigatus/imunologia , Aspergillus niger/imunologia , Imunoglobulina G/sangue , Aspergilose Pulmonar/epidemiologia , Tuberculose Pulmonar/epidemiologia , Adulto , Idoso , Anticorpos Antifúngicos/sangue , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Aspergilose Pulmonar/sangue , Sensibilidade e Especificidade , Estudos Soroepidemiológicos , Caracteres Sexuais , Taiwan/epidemiologia , Adulto Jovem
2.
Int J Tuberc Lung Dis ; 22(1): 7-16, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29297421

RESUMO

In countries with low and moderate incidence of tuberculosis (TB), the disease tends to concentrate in specific high-risk populations such as people with diabetes mellitus (DM). We review the updated evidence on the association between 1) DM and active TB, and 2) DM and latent tuberculous infection (LTBI), and 3) we summarize the findings on the population-level impact of DM on TB epidemiology, with particular focus on low- and moderate-incidence settings. We conducted an updated review of studies on DM and active TB, and found 11 more cohort studies published after the previous systematic review from 2008. The updated pooled relative risk (RR) (2.03, 95%CI 1.62-2.55) of all the studies was substantially lower than the three-fold risk increase in the previous review. Substantial heterogeneity of RR across studies was found. Possible reasons for such heterogeneity include different levels of residual confounding, the effect of modification by age, and different levels of glycemic control in the population. In a recently published systematic review on DM and LTBI, one cohort study and 12 cross-sectional studies were identified. The results from cross-sectional studies suggest a significant but modestly increased risk of LTBI among patients with DM (pooled odds ratio 1.18, 95%CI 1.06-1.30). We reviewed evidence on the population-level impact of DM on TB epidemiology in studies using population-attributable fraction analysis and infectious disease modelling. Those studies revealed that DM accounted for a substantial TB burden in low- and moderate-incidence countries. Finally, we discussed the complex association of obesity, DM and TB risk and the impact of the global obesity pandemic on TB epidemiology.


Assuntos
Diabetes Mellitus/epidemiologia , Tuberculose Latente/epidemiologia , Tuberculose/epidemiologia , Efeitos Psicossociais da Doença , Saúde Global , Humanos , Incidência , Risco , Fatores de Risco
3.
J Helminthol ; 91(5): 642-646, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27628641

RESUMO

Sparganosis is one of the top three tissue-dwelling heterologous helminthic diseases, along with cysticercosis and paragonimiasis, in Korea. Due to a lack of effective early diagnosis and treatment methods, this parasitic disease is regarded as a public health threat. This study evaluated reactivity, against sparganum extracts, of sera from inhabitants of Cheorwon-gun, Goseong-gun and Ongjin-gun in Korea. The sera from 836 subjects were subjected to enzyme-linked immunosorbent assay and immunoblot analysis. The sera from 18 (5.8%) and 15 (5.1%) inhabitants in Cheorwon-gun (n = 312) and Goseong-gun (n = 294), respectively, exhibited highly positive reactions to the sparganum antigen, whereas only two (0.9%) inhabitants in Ongjin-gun (n = 230) showed positivity. We sought antigenic proteins for serodiagnosis of positive sera by immunoproteomic approaches. Total sparganum lysates were separated by two-dimensional electrophoresis and then subjected to immunoblot analysis with mixed sparganosis-positive sera. We found seven antigenic spots and identified paramyosin as an antigenic protein by liquid chromatography-mass spectrometry. By two-dimensional (2D)-based mass analysis and immunoblotting against sparganosis-positive sera, paramyosin was identified as a candidate antigen for serodiagnosis of sparganosis.


Assuntos
Anticorpos Anti-Helmínticos/sangue , Antígenos de Helmintos/imunologia , Testes Sorológicos/métodos , Esparganose/diagnóstico , Plerocercoide/imunologia , Tropomiosina/imunologia , Animais , Antígenos de Helmintos/análise , Cromatografia Líquida , Eletroforese em Gel Bidimensional , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Immunoblotting , Espectrometria de Massas , Proteoma/análise , República da Coreia , Plerocercoide/química , Tropomiosina/análise
4.
Leukemia ; 30(1): 144-53, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26202933

RESUMO

Although hematopoietic stem cells (HSC) are the best characterized and the most clinically used adult stem cells, efforts are still needed to understand how to best ex vivo expand these cells. Here we present our unexpected finding that OCT4 is involved in the enhancement of cytokine-induced expansion capabilities of human cord blood (CB) HSC. Activation of OCT4 by Oct4-activating compound 1 (OAC1) in CB CD34(+) cells enhanced ex vivo expansion of HSC, as determined by a rigorously defined set of markers for human HSC, and in vivo short-term and long-term repopulating ability in NSG mice. Limiting dilution analysis revealed that OAC1 treatment resulted in 3.5-fold increase in the number of SCID repopulating cells (SRCs) compared with that in day 0 uncultured CD34(+) cells and 6.3-fold increase compared with that in cells treated with control vehicle. Hematopoietic progenitor cells, as assessed by in vitro colony formation, were also enhanced. Furthermore, we showed that OAC1 treatment led to OCT4-mediated upregulation of HOXB4. Consistently, siRNA-mediated knockdown of HOXB4 expression suppressed effects of OAC1 on ex vivo expansion of HSC. Our study has identified the OCT4-HOXB4 axis in ex vivo expansion of human CB HSC.


Assuntos
Sangue Fetal/citologia , Células-Tronco Hematopoéticas/fisiologia , Proteínas de Homeodomínio/genética , Fator 3 de Transcrição de Octâmero/fisiologia , Fatores de Transcrição/genética , Animais , Células Cultivadas , Regulação da Expressão Gênica , Humanos , Camundongos
5.
Clin Microbiol Infect ; 21(3): 250.e1-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25658545

RESUMO

Very few studies have focused on the outcome and management of patients with a single sputum isolate of nontuberculous mycobacterium (NTM) on initial examination. Patients with a single isolate of Mycobacterium avium complex (MAC), M. chelonae-abscessus, M. kansasii, or M. fortuitum from at least three sputum samples collected within 1 month were retrospectively identified. Those with follow-up sputum samples within 1 year were included in the analysis. Among the 202 patients included, M. fortuitum (n = 71, 35.1%) and MAC (n = 70, 34.7%) were the most common NTM species isolated, followed by M. chelonae-abscessus (n = 40, 19.8%) and M. kansasii (n = 21, 10.4%). The mean clinical follow-up period was 26.2 months. Forty-four patients (21.8%) had subsequent positive cultures of the same NTM species, while eight (4.0%) had bronchiectasis and developed NTM lung disease (NTM-LD). Neither patients without bronchiectasis nor those with M. fortuitum subsequently developed NTM lung disease. Among bronchiectatic patients with NTM other than M. fortuitum, age ≤65 years (p 0.006, OR 32.13), malignancy (p 0.048, OR 14.35), and initial radiographic score >2 (p 0.027, OR 20.06) were associated with subsequent NTM-LD. In all of the NTM patients, bronchiectasis (p <0.001, OR 5.46) and age ≤65 years (p 0.002, OR 3.29) were significantly associated with subsequent positive NTM culture. In patients with a single isolation of NTM from respiratory specimens, the presence of bronchiectasis and younger age indicates higher risk of subsequent culture-positivity and NTM-LD. Single isolation of M. fortuitum is of little clinical significance. Other patients with NTM, younger age, and more severe radiographic pulmonary lesion also warrant further attention.


Assuntos
Infecções por Mycobacterium não Tuberculosas/epidemiologia , Infecções por Mycobacterium não Tuberculosas/microbiologia , Micobactérias não Tuberculosas/isolamento & purificação , Pneumonia Bacteriana/epidemiologia , Pneumonia Bacteriana/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Mycobacterium não Tuberculosas/diagnóstico , Razão de Chances , Pneumonia Bacteriana/diagnóstico , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Taiwan/epidemiologia , Adulto Jovem
6.
Cell Death Dis ; 5: e1113, 2014 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-24625972

RESUMO

Endoplasmic reticulum (ER) stress is considered one of the pathological mechanisms of idiopathic pulmonary fibrosis (IPF). Therefore, we examined whether an ER stress regulator, Bax inhibitor-1 (BI-1), regulates collagen accumulation, which is both a marker of fibrosis and a pathological mechanism of fibrosis. The presence of BI-1 inhibited the transforming growth factor-ß1-induced epithelial-mesenchymal transition of epithelial pulmonary cells and bleomycin-induced pulmonary fibrosis in a mouse model by enhancing collagen degradation, most likely by enhanced activation of the lysosomal V-ATPase through glycosylation. We also found a correlation between post-translational glycosylation of the V-ATPase and its associated chaperone, calnexin, in BI-1-overexpressing cells. BI-1-induced degradation of collagen through lysosomal V-ATPase glycosylation and the involvement of calnexin were confirmed in a bleomycin-induced fibrosis mouse model. These results highlight the regulatory role of BI-1 in IPF and reveal for the first time the role of lysosomal V-ATPase glycosylation in IPF.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Colágeno/metabolismo , Células Epiteliais/enzimologia , Pulmão/enzimologia , Proteínas de Membrana/metabolismo , Processamento de Proteína Pós-Traducional , Fibrose Pulmonar/enzimologia , ATPases Vacuolares Próton-Translocadoras/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Bleomicina , Calnexina/metabolismo , Calreticulina/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Estresse do Retículo Endoplasmático , Ativação Enzimática , Células Epiteliais/patologia , Transição Epitelial-Mesenquimal , Glicosilação , Humanos , Pulmão/patologia , Lisossomos/metabolismo , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Proteólise , Fibrose Pulmonar/induzido quimicamente , Fibrose Pulmonar/patologia , Fatores de Tempo , Transfecção , Fator de Crescimento Transformador beta1/metabolismo
7.
Eur J Clin Microbiol Infect Dis ; 33(7): 1143-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24458500

RESUMO

Stenotrophomonas maltophilia can cause various clinical diseases; however, pleural infections due to S. maltophilia are rare. We evaluated the clinical characteristics and outcomes of patients with pleural infections (complicated parapneumonic effusion or empyema) due to S. maltophilia who were treated at a medical center in Taiwan from 2004 to 2012. During the study period, 40 patients were treated for pleural infections due to S. maltophilia. The incidence of S. maltophilia pleural infections ranged from 2.66 per 1,000,000 patient-days in 2009 to 12.44 per 1,000,000 patient-days in 2011. Most of the patients with S. maltophilia pleural infections were immunocompromised male adults and all of the infections were acquired in healthcare settings. The majority of patients had polymicrobial pleural infections (n = 31, 77.5 %) and the most common pathogen was Pseudomonas aeruginosa (n = 12). The causes of pleural infections due to S. maltophilia were pneumonia due to S. maltophilia in two patients (5 %), post-surgical/tube thoracostomy in 26 (65 %) patients, and fistula (bronchopleural, esophagopleural and biliopleural) in 12 (30 %) patients. The 14-day and 30-day mortality rates were 32.5 % and 42.5 %, respectively. Pleural infections due to S. maltophilia are most commonly the result of surgical procedures, thoracostomy, and underlying fistulas. These infections are associated with a high mortality rate, especially among immunocompromised patients.


Assuntos
Empiema Pleural/patologia , Infecções por Bactérias Gram-Negativas/patologia , Derrame Pleural/patologia , Stenotrophomonas maltophilia/isolamento & purificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Coinfecção/epidemiologia , Coinfecção/microbiologia , Coinfecção/patologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/patologia , Empiema Pleural/epidemiologia , Empiema Pleural/microbiologia , Feminino , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Hospedeiro Imunocomprometido , Incidência , Masculino , Pessoa de Meia-Idade , Derrame Pleural/epidemiologia , Derrame Pleural/microbiologia , Infecção da Ferida Cirúrgica/epidemiologia , Infecção da Ferida Cirúrgica/microbiologia , Infecção da Ferida Cirúrgica/patologia , Taiwan/epidemiologia , Resultado do Tratamento , Adulto Jovem
8.
J Appl Microbiol ; 113(4): 807-14, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22805203

RESUMO

AIMS: This study examined the biotransformation pathway of ginsenoside Rb(1) by the fungus Esteya vermicola CNU 120806. METHODS AND RESULTS: Ginsenosides Rb(1) and Rd were extracted from the root of Panax ginseng. Liquid fermentation and purified enzyme hydrolysis were employed to investigate the biotransformation of ginsenoside Rb(1) . The metabolites were identified and confirmed using NMR analysis as gypenoside XVII and gypenoside LXXV. A mole yield of 95·4% gypenoside LXXV was obtained by enzymatic conversion (pH 5·0, temperature 50°C). Ginsenoside Rd was used to verify the transformation pathway under the same reaction condition. The product Compound K (mole yield 49·6%) proved a consecutive hydrolyses occurred at the C-3 position of ginsenoside Rb(1) . CONCLUSIONS: Strain CNU 120806 showed a high degree of specific ß-glucosidase activity to convert ginsenosides Rb(1) and Rd to gypenoside LXXV and Compound K, respectively. The maximal activity of the purified glucosidase for ginsenosides transformation occurred at 50°C and pH 5·0. Compared with its activity against pNPG (100%), the ß-glucosidase exhibited quite lower level of activity against other aryl-glycosides. Enzymatic hydrolysate, gypenoside LXXV and Compound K were produced by consecutive hydrolyses of the terminal and inner glucopyranosyl moieties at the C-3 carbon of ginsenoside Rb(1) and Rd, giving the pathway: ginsenoside Rb(1) → gypenoside XVII → gypenoside LXXV; ginsenoside Rd→F(2) →Compound K, but did not hydrolyse the 20-C, ß-(1-6)-glucoside of ginsenoside Rb(1) and Rd. SIGNIFICANCE AND IMPACT OF THE STUDY: The results showed an important practical application on the preparation of gypenoside LXXV. Additionally, this study for the first time provided a high efficient preparation method for gypenoside LXXV without further conversion, which also gives rise to a potential commercial enzyme application.


Assuntos
Ginsenosídeos/metabolismo , Ophiostomatales/metabolismo , Biotransformação , Fermentação , Glicosídeos/metabolismo , Gynostemma/metabolismo , Hidrólise , Ophiostomatales/enzimologia , Panax/química , Extratos Vegetais/metabolismo , Raízes de Plantas/química , beta-Glucosidase/metabolismo
9.
J Dairy Sci ; 94(6): 2692-700, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21605738

RESUMO

A curd-washing step is used in the manufacture of Colby cheese to decrease the residual lactose content and, thereby, decrease the potential formation of excessive levels of lactic acid. The objective of this study was to investigate the effect of different washing methods on the Ca equilibrium and rheological properties of Colby cheese. Four different methods of curd-washing were performed. One method was batch washing (BW), where cold water (10°C) was added to the vat, with and without stirring, where curds were in contact with cold water for 5 min. The other method used was continuous washing (CW), with or without stirring, where curds were rinsed with continuously running cold water for approximately 7 min and water was allowed to drain immediately. Both methods used a similar volume of water. The manufacturing pH values were similar in all 4 treatments. The insoluble (INSOL) Ca content of cheese was measured by juice and acid-base titration methods and the rheological properties were measured by small amplitude oscillatory rheology. The levels of lactose in cheese at 1 d were significantly higher in CW cheese (0.06-0.11%) than in BW cheeses (∼0.02%). The levels of lactic acid at 2 and 12 wk were significantly higher in CW cheese than in BW cheeses. No differences in the total Ca content of cheeses were found. Cheese pH increased during ripening from approximately 5.1 to approximately 5.4. A decrease in INSOL Ca content of all cheeses during ripening occurred, although a steady increase in pH took place. The initial INSOL Ca content as a percent of total Ca in cheese ranged from 75 to 78% in all cheeses. The INSOL Ca content of cheese was significantly affected by washing method. Stirring during manufacturing did not have a significant effect on the INSOL Ca content of cheese during ripening. Batch-washed cheeses had significantly higher INSOL Ca contents than did CW cheeses during the first 4 wk of ripening. The maximum loss tangent values (meltability index) of CW cheese at 1 d and 1 wk were significantly higher compared with those of BW cheeses. In conclusion, different curd washing methods have a significant effect on the levels of lactose, lactic acid, meltability, and INSOL Ca content of Colby cheese during ripening.


Assuntos
Cálcio/química , Queijo/análise , Manipulação de Alimentos/métodos , Animais , Reologia , Solubilidade
10.
J Hosp Infect ; 78(1): 45-9, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21269734

RESUMO

We studied twenty patients with Leuconostoc spp. bacteraemia at a tertiary hospital in northern Taiwan between 1995 and 2008. All isolates were identified to species level using conventional and commercial automated methods in conjunction with 16S rRNA sequencing analysis. Leuconostoc lactis (15/20, 75%) constituted the most common species but required molecular methods for accurate identification. Minimum inhibitory concentrations (MICs) of 10 antimicrobial agents were determined using the broth microdilution method. Among these 20 patients, 19 had healthcare-associated Leuconostoc spp. bacteraemia and 11 patients (55%) had underlying malignancies. Eleven had been hospitalised for more than 30 days (median: 32.5 days; range: 0-252 days) before the bacteraemic episode. At the time of bacteraemia, 11 had a Pitt bacteraemia score of ≥ 4 (median: 4; range: 0-7) and 12 had a modified Acute Physiological Assessment and Chronic Health Evaluation (APACHE II) score of ≥ 20 (median: 22; range: 5-37). Azithromycin (MIC: 0.12 µg/mL), moxifloxacin (MIC: 0.25-0.5 µg/mL), daptomycin (MIC: 0.03-0.25 µg/mL) and tigecycline (MIC: 0.06-0.12 µg/mL) exhibited good in vitro activity against Leuconostoc spp. although bacteraemia due to L. lactis was associated with high mortality in immunocompromised patients.


Assuntos
Bacteriemia/epidemiologia , Infecção Hospitalar/epidemiologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Leuconostoc/isolamento & purificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Bacteriemia/microbiologia , Bacteriemia/mortalidade , Técnicas Bacteriológicas/métodos , Criança , Infecção Hospitalar/microbiologia , Infecção Hospitalar/mortalidade , Feminino , Infecções por Bactérias Gram-Positivas/microbiologia , Infecções por Bactérias Gram-Positivas/mortalidade , Hospitais Universitários , Humanos , Leuconostoc/classificação , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Técnicas de Diagnóstico Molecular/métodos , Fatores de Risco , Taiwan/epidemiologia , Adulto Jovem
11.
Clin Microbiol Infect ; 17(8): 1226-31, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21040157

RESUMO

Human infections caused by Weissella confusa are rarely reported. Ten patients with bacteraemia caused by W. confusa who were treated at a tertiary-care hospital in Taiwan during 1997-2007 were studied. All isolates were initially misidentified as various Lactobacillus and Leuconostoc species by two commercial automated identification methods, and were confirmed to be W. confusa by 16S rRNA sequencing analysis. MICs of these isolates for ten antimicrobial agents were determined by the agar dilution method. The characteristics of these patients included underlying malignancy (n = 4), presence of a central catheter (n = 6), surgery within the previous 3 months (n = 4) and concomitant polymicrobial bacteraemia (n = 5, 50%). Mortality was directly attributed to bacteraemia in two patients. All isolates exhibited high trimethoprim-sulphamethoxazole and ceftazidime MICs (≥ 128 mg/L) and were inhibited by linezolid, daptomycin, ceftobiprole and tigecycline at 4, 0.12, 2 and 0.12 mg/L, respectively. In conclusion, W. confusa should be included in the list of organisms causing bacteraemia in immunocompromised hosts. Novel antibiotics, including daptomycin, moxifloxacin, doripenem and tigecycline, exert good activity against W. confusa.


Assuntos
Bacteriemia/epidemiologia , Infecções por Bactérias Gram-Positivas/epidemiologia , Hospitais Universitários/estatística & dados numéricos , Weissella/classificação , Weissella/isolamento & purificação , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Bacteriemia/microbiologia , Bacteriemia/mortalidade , Feminino , Infecções por Bactérias Gram-Positivas/microbiologia , Infecções por Bactérias Gram-Positivas/mortalidade , Humanos , Hospedeiro Imunocomprometido , Masculino , Testes de Sensibilidade Microbiana/métodos , Pessoa de Meia-Idade , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Taiwan/epidemiologia , Weissella/efeitos dos fármacos , Weissella/genética
12.
J Dairy Sci ; 93(5): 1844-53, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20412897

RESUMO

Colby cheese was made using different manufacturing conditions (i.e., varying the lactose content of milk and pH values at critical steps in the cheesemaking process) to alter the extent of acid development and the insoluble and total Ca contents of cheese. Milk was concentrated by reverse osmosis (RO) to increase the lactose content. Extent of acid development was modified by using high (HPM) and low (LPM) pH values at coagulant addition, whey drainage, and curd milling. Total Ca content was determined by atomic absorption spectroscopy, and the insoluble (INSOL) Ca content of cheese was measured by the cheese juice method. The rheological and melting properties of cheese were measured by small amplitude oscillatory rheometry and UW-Melt Profiler, respectively. There was very little change in pH during ripening even in cheese made from milk with high lactose content. The initial (d 1) cheese pH was in the range of 4.9 to 5.1. The INSOL Ca content of cheese decreased during the first 4 wk of ripening. Cheeses made with the LPM had lower INSOL Ca content during ripening compared with cheese made with HPM. There was an increase in melt and maximum loss tangent values during ripening except for LPM cheeses made with RO-concentrated milk, as this cheese had pH <4.9 and exhibited limited melt. Curd washing reduced the levels of lactic acid produced during ripening and resulted in significantly higher INSOL Ca content. The use of curd washing for cheeses made from high lactose milk prevented a large pH decrease during ripening; high rennet and draining pH values also retained more buffering constituents (i.e., INSOL Ca phosphate), which helped prevent a large pH decrease.


Assuntos
Cálcio/análise , Queijo/análise , Queijo/normas , Manipulação de Alimentos , Leite/química , Animais , Concentração de Íons de Hidrogênio , Lactose/química , Reologia , Fatores de Tempo
13.
J Dairy Sci ; 88(11): 3798-809, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16230685

RESUMO

Cheddar cheese was made from milk concentrated by reverse osmosis (RO) to increase the lactose content or from whole milk. Manufacturing parameters (pH at coagulant addition, whey drainage, and milling) were altered to produce cheeses with different total Ca contents and low pH values (i.e., <5.0) during ripening. The concentration of insoluble (INSOL) Ca in cheese was measured by cheese juice method, buffering by acid-base titration, rheological properties by small amplitude oscillatory rheometry, and melting properties by UW-Melt Profiler. The INSOL Ca content as a percentage of total Ca in all cheeses rapidly decreased during the first week of aging but surprisingly did not decrease below approximately 41% even in cheeses with a very low pH (e.g., approximately 4.7). Insoluble Ca content in cheese was positively correlated (r = 0.79) with cheese pH in both RO and nonRO treatments, reflecting the key role of pH and acid development in altering the extent of solubilization of INSOL Ca. The INSOL Ca content in cheese was positively correlated with the maximum loss tangent value from the rheology test and the degree of flow from the UW-Melt Profiler. When cheeses with pH <5.0 where heated in the rheometer the loss tangent values remained low (<0.5), which coincided with limited meltability of Cheddar cheeses. We believe that this lack of meltability was due to the dominant effects of reduced electrostatic repulsion between casein particles at low pH values (<5.0).


Assuntos
Cálcio/análise , Queijo/análise , Animais , Caseínas/análise , Caseínas/química , Fenômenos Químicos , Físico-Química , Manipulação de Alimentos/métodos , Concentração de Íons de Hidrogênio , Lactose/análise , Leite , Osmose , Reologia , Solubilidade , Eletricidade Estática
14.
Science ; 281(5380): 1165-8, 1998 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-9712574

RESUMO

Nanometer-size presolar diamonds from the Efremovka CV3 chondrite were physically separated into several grain size fractions by ultracentrifugation. The coarsest size fraction is the most enriched in carbon-12; the others have broadly similar carbon isotopic compositions. Measurement of noble gases shows that their concentration decreases with decreasing grain size. This effect is attributed to ion implantation. Such an episode could occur in the envelope of a supernova that produced the diamonds, or in interstellar space; in either case, ions with energies above a certain threshold pass completely through the smaller diamond grains without being captured. Concentrations of nitrogen show only minor variations with grain size, indicating a different mechanism of incorporation into the diamonds.

15.
Cryobiology ; 34(1): 70-9, 1997 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9028917

RESUMO

The heteropteran Pyrrhocoris apterus (L.) does not survive freezing of its body fluids; there is a good correlation between values of survival at subzero temperatures and the supercooling point (SCP), i.e., the temperature at which body fluids start to freeze. The decrease of the SCP and thus the increase in cold hardiness is regulated by photoperiod and temperature. The relative importance of these factors depends on the physiological state of the insect. The SCP is about -7°C at the onset of prediapause and a decrease of about 4-5°C is associated with the development of the diapause syndrome in adults; these processes both are induced by a short-day photoperiod with temperature playing a secondary role. The induction of the diapause syndrome is a prerequisite for the subsequent decrease of the SCP by about 5-6°C during cold acclimation. An intermediate temperature of 15°C, or fluctuating outdoor temperatures and short-day photoperiods, are more suitable for the decrease of SCP than 5°C in continuous darkness. The sensitivity to photoperiod gradually disappears during the development of diapause; after the termination of diapause around the winter solstice the SCP irreversibly increases at a high temperature of 26°C even if exposed to a short-day photoperiod. The SCPs of hemolymph, gut, fat body, and gonads were compared to whole-body SCP. The gut was identified as the primary site of ice nucleation because its SCP value was very similar to the value for the whole body in both short-day and long-day insects. The SCPs of other organs, including the hemolymph, were always lower than the whole body SCP. Food was not a source of ice nucleating agents because the SCP of freshly ecdysed adults remained high after 2 weeks of starvation. In contrast, feeding was a prerequisite for the decrease of the SCP during prediapause. In postdiapause insects, the SCP increased at high temperatures in spite of the absence of food.

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