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1.
J Dairy Sci ; 107(7): 4381-4393, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38278298

RESUMO

The objectives of this retrospective observational study were to investigate the association between BCS at 21 d before calving with prepartum and postpartum DMI, energy balance (EB), and milk yield. Data from 427 multigravid cows from 11 different experiments conducted at the University of Florida (Gainesville, FL) were used. Cows were classified according to their BCS at 21 d before calving as fat (BCS ≥ 4.00; n = 83), moderate (BCS = 3.25-3.75; n = 287), and thin (BCS ≤ 3.00; n = 57). Daily DMI from -21 to -1 and from +1 to +28 DIM was individually recorded. Energy balance was calculated as the difference between net energy for lactation consumed and required. Dry matter intake in fat cows was lower than that in moderate and thin cows both prepartum (fat = 9.97 ± 0.21, moderate = 11.15 ± 0.14, and thin = 11.92 ± 0.22 kg/d) and postpartum (fat = 14.35 ± 0.49, moderate = 15.47 ± 0.38, and thin = 16.09 ± 0.47 kg/d). Dry matter intake was also lower for moderate cows compared with thin cows prepartum, but not postpartum. Energy balance in fat cows was lower than in moderate and thin cows both prepartum (fat = -4.16 ± 0.61, moderate = -1.20 ± 0.56, and thin = 0.88 ± 0.62 Mcal/d) and postpartum (fat = -12.77 ± 0.50, moderate = -10.13 ± 0.29, and thin = -6.14 ± 0.51 Mcal/d). Energy balance was also lower for moderate cows compared with thin cows both prepartum and postpartum. There was a quadratic association between BCS at 21 d before calving and milk yield. Increasing BCS from 2.5 to 3.5 was associated with an increase in daily milk yield of 6.0 kg and 28 d cumulative milk of 147 kg. Increasing BCS from 3.5 to 4.5 was associated with a decrease in daily milk yield of 4.4 kg and 28 d cumulative milk of 116 kg. In summary, a moderate BCS at 21 d before calving was associated with intermediate DMI and EB pre- and postpartum but greater milk yield compared with thinner and fatter cows. Our findings indicate that a moderate BCS is ideal for ensuring a successful lactation.


Assuntos
Metabolismo Energético , Lactação , Leite , Período Pós-Parto , Animais , Bovinos , Feminino , Leite/metabolismo , Gravidez , Estudos Retrospectivos , Dieta/veterinária
2.
J Dairy Sci ; 104(2): 2357-2368, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33246618

RESUMO

Multiparous, nonlactating pregnant cows are negatively affected by heat stress, but the effect of heat stress on more thermotolerant pregnant heifers has received less attention. Our objective was to characterize the effect of late-gestation heat abatement on thermoregulatory responses and subsequent milk production of nulliparous Holstein heifers. Pregnant heifers, blocked by body condition score (BCS) and predicted transmitting ability (PTA) for milk, were enrolled in either heat stress (HT, shade of freestall barn; n = 16) or cooling (CL, shade of freestall barn, water soakers, and fans; n = 15) environments during the last 60 d of pregnancy (~8 weeks). Rectal temperature (RT; thermometer), respiration rate (RR; breaths/min), sweating rate (SR; VapoMeter, Delfin Technologies, Kuopio, Finland), and skin temperature (ST; infrared thermometer) were measured thrice weekly from enrollment to calving. Vaginal temperature (VT; i-button intravaginal device) was measured every 10 min for 7 consecutive days at wk -8, -6, -4, and -2 relative to calving and averaged hourly. Daily thermoregulatory patterns assessed by SR and ST, were measured every 4 h over a 36-h time interval at wk -6, -4, and -2 relative to calving. Upon calving, milk, protein, and fat yields were recorded twice daily for 15 wk. The average temperature-humidity index (Hobo Pro temperature probe, Onset Computer Corporation, Pocasset, MA) in the barn during the precalving period was 77 (minimum of 72, maximum of 82). Only heifers that gave birth to a female calf (CL = 12, HT = 14) were included in the statistical analysis. In the precalving period, CL heifers had lower RR (44.3 vs. 60.0 ± 1.6 breaths/min), RT (38.7 vs. 38.8 ± 0.04°C), unshaved ST (34.7 vs. 35.3 ± 0.17°C), and unshaved SR (19.0 vs. 35.2 ± 1.9 g/m2h), relative to HT heifers. Additionally, VT was lower in CL heifers during wk -4, and -2, specifically during early morning and early afternoon hours. When measured over a 36-h time interval, ST and SR were lower in CL heifers, when compared with HT heifers for all weeks. Notably, ST was reduced overnight and SR was reduced during the daytime. Cooled heifers had higher milk yield (35.8 vs. 31.9 ± 1.4 kg/d), when compared with HT heifers. Similar to multiparous cows, our data indicate that actively cooling heifers in late pregnancy is effective in promoting thermoregulation and results in elevated milk production postcalving.


Assuntos
Regulação da Temperatura Corporal/fisiologia , Doenças dos Bovinos/prevenção & controle , Transtornos de Estresse por Calor/veterinária , Resposta ao Choque Térmico , Lactação/fisiologia , Animais , Bovinos , Temperatura Baixa , Indústria de Laticínios , Feminino , Finlândia , Idade Gestacional , Transtornos de Estresse por Calor/prevenção & controle , Temperatura Alta , Umidade , Leite , Gravidez , Taxa Respiratória , Temperatura
3.
J Dairy Sci ; 103(2): 1969-1981, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31864734

RESUMO

Eleven mid-lactation Holstein cows were milked twice daily during the first 2 experimental weeks. During wk 3 to 10, the cows were differentially milked: right quarters were milked thrice daily (3×) and left quarters were milked once daily (1×). During wk 11 to 14, all quarters were milked twice daily. After 4 wk of differential milking, the cows received daily i.m. injections of the dopamine antagonist domperidone (DOMP; 300 mg; n = 6) or of dimethyl sulfoxide as the control (CTL; n = 5) for 8 wk (wk 7-14). During the differential milking period (wk 3-6), milk production was greater for quarters milked 3× than for those milked 1× but did not differ between DOMP and CTL cows. During the differential milking + injection period (wk 7-10), milk production continued to differ according to milking frequency. However, DOMP injection did not have an effect or interact with milking frequency on milk production. During the injection period (wk 11-14), milk production remained greater in the quarters previously milked 3× and milk production increased in DOMP injected cows but not in CTL cows. Injections of DOMP increased prolactin concentration, which was greater in the serum of DOMP cows than in that of CTL cows during the differential milking + injection and the injection periods. The expression of genes that are directly related to milk synthesis (CSN2, LALBA, and ACACA) was greater in the 3× quarters than in the 1× quarters. In addition, DOMP increased CSN2 expression during the injection period. The expression of both isoforms of the PRLR gene was greater in the 3× quarters during the differential milking + injection and the injection periods. At the protein level, injections of DOMP tended to increase the number of long PRLR isoform during the differential milking + injection period. The number of short PRLR isoform was greater in the 1× quarters than in the 3× quarters during the differential milking, the differential milking + injection, and the injection periods. The total amount of STAT3 protein was greater in the 1× quarters during the differential milking and the differential milking + injection periods. The amount of phosphorylated STAT3 protein was greater in the 1× quarters during the differential milking period. The total amount of phosphorylated STAT5 protein was greater in the 3× quarters during the differential milking and the differential milking + injection periods. The results of this experiment support the hypothesis that the responsiveness of the mammary gland to PRL is modulated by milking frequency, although the underlying mechanism remains to be determined.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios/métodos , Domperidona/administração & dosagem , Antagonistas de Dopamina/administração & dosagem , Leite/metabolismo , Prolactina/sangue , Transdução de Sinais/efeitos dos fármacos , Animais , Feminino , Lactação/efeitos dos fármacos , Glândulas Mamárias Animais/fisiologia , Leite/química , Fosforilação , Prolactina/efeitos dos fármacos , Fator de Transcrição STAT5/metabolismo , Serotonina/análise , Fatores de Tempo
4.
Nature ; 482(7385): 375-8, 2012 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22337057

RESUMO

η Carinae is one of the most massive binary stars in the Milky Way. It became the second-brightest star in our sky during its mid-nineteenth-century 'Great Eruption', but then faded from view (with only naked-eye estimates of brightness). Its eruption is unique in that it exceeded the Eddington luminosity limit for ten years. Because it is only 2.3 kiloparsecs away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that during its nineteenth-century eruption, η Car ejected more than ten solar masses in an event that released ten per cent of the energy of a typical core-collapse supernova, without destroying the star. Here we report observations of light echoes of η Carinae from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km s(-1), in good agreement with predicted expansion speeds. The light-echo spectra correlate best with those of G2-to-G5 supergiants, which have effective temperatures of around 5,000 kelvin. In contrast to the class of extragalactic outbursts assumed to be analogues of the Great Eruption of η Carinae, the effective temperature of its outburst is significantly lower than that allowed by standard opaque wind models. This indicates that other physical mechanisms such as an energetic blast wave may have triggered and influenced the eruption.

5.
J Oral Rehabil ; 45(10): 819-835, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29908034

RESUMO

Temporomandibular disorder (TMD) is an umbrella condition presenting several signs and symptoms including pain in the temporomandibular joint (TMJ) and masticatory muscles, articular noises, earache, headache, irregular or restricted jaw function, chewing difficulty, and limited mouth opening. Such TMD impairment may cause disorders during the chewing process. Therefore, the purpose of this systematic review was to assess chewing dysfunctions measured by sEMG, and their association with TMD. A combination and variation in the descriptors "temporomandibular joint disorders", "masticatory dysfunctions", and electromyography were used to perform the searches across databases. The databases chosen were: LILACS, PubMed, Science Direct, Scopus, and Web of Science. Additionally, grey literature was assessed using Google Scholar, ProQuest, and OpenGrey. Studies in adults that diagnosed TMD through the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) or Helkimo Protocol were selected. Furthermore, those studies should have evaluated chewing processes through surface electromyography (sEMG). Risk of bias of the included studies was assessed through the Meta-Analysis of Statistics Assessment and Review Instrument (MAStARI) tool. Eleven included studies shown significant results; however, they evaluated discrepant parameters, presented high inconsistency in the application, and had chosen different tasks to analyse the sEMG and hence, there was no consensus in the results of studies. In conclusion, strength of recommendations was very low due to a series of limitations on studies and it was not possible to made categorical statement about association between TMD and chewing dysfunctions in adults when parameters of sEMG were analysed.


Assuntos
Bruxismo/fisiopatologia , Dor Facial/fisiopatologia , Cefaleia/fisiopatologia , Mastigação/fisiologia , Músculos da Mastigação/fisiopatologia , Transtornos da Articulação Temporomandibular/fisiopatologia , Eletromiografia , Dor Facial/etiologia , Cefaleia/etiologia , Humanos , Músculos da Mastigação/diagnóstico por imagem , Amplitude de Movimento Articular , Reprodutibilidade dos Testes , Transtornos da Articulação Temporomandibular/diagnóstico por imagem
6.
J Oral Rehabil ; 43(6): 468-79, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26749516

RESUMO

The most common temporomandibular disorders (TMD) signs and symptoms are related to muscle sensitivity through palpation, restricted mouth opening, asymmetric mandibular movements, joint sounds, pain and otologic signs and symptoms. To date, counselling, occlusal splints, exercises, biofeedback and acupuncture are examples of conservative modalities proposed for TMD therapy. The aim of this systematic review was to investigate the effect of these conservative therapies for TMD on otologic signs and symptoms. The authors searched the following electronic databases published up to 1st May 2015: PubMed, LILACS, Scopus, Web of Science and Science Direct with no time or language limitations. Using a two-phase selection process, the authors identified 08 articles and used them to conduct a qualitative analysis. Methodological quality of each article was performed with the aid of 'Quality Assessment of a Cohort Study' and 'Quality Assessment of a Randomized Clinical Trial', developed by the Dutch Cochrane Centre, a centre of the Cochrane Collaboration. This systematic review showed in seven of the eight studies included that a total or partial resolution of otologic complains occurred after counselling, exercise therapies and occlusal splint therapy. Upon the limitations of the studies included in this systematic review, the present outcomes suggested that there is insufficient evidence in favour or against the conservative therapies for TMD on changes in otologic signs and symptoms. Thus, further studies with a higher level of evidence and more representative samples should be conducted to better understand the relationship of TMD therapy changes on otologic complains.


Assuntos
Aconselhamento/métodos , Terapia por Exercício/métodos , Dor Facial/reabilitação , Placas Oclusais/estatística & dados numéricos , Autocuidado/métodos , Transtornos da Articulação Temporomandibular/reabilitação , Transtornos da Articulação Temporomandibular/terapia , Dor Facial/etiologia , Dor Facial/terapia , Humanos , Medição da Dor , Qualidade de Vida , Transtornos da Articulação Temporomandibular/complicações , Resultado do Tratamento
7.
JDS Commun ; 1(1): 21-24, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36340427

RESUMO

Previous studies have documented the negative effects of heat stress during the dry period on dairy cow performance during the next lactation, but an easy method to assess heat stress for dry cow management is lacking. In an effort to determine a threshold for heat stress based on the physiological response of respiration rate, an easily measured variable, an analysis including data collected from 6 different studies (n = 144 cows) was performed to summarize the correlations among rectal temperature (RT) and respiration rate (RR) during the dry period, milk production during the first 8 wk of lactation (MK), calf birth weight (CW), body weight at calving (BW), gestation length (GL), and dry matter intake (DMI) pre- and postpartum. Studies were conducted in Florida during the summer, and dry cows were assigned to 2 treatments: heat stress (only shade; HT, n = 75 cows) and cooling (shade, fans, and soakers; CL, n = 69 cows). Average RT (0.3°C) and RR [26 breaths per min (bpm)] of HT cows increased compared with CL. In addition, the CL group produced more milk (2.8 kg/d) during the first 8 wk of the subsequent lactation relative to HT. Correlation analysis indicated that RR of HT was negatively correlated with MK and GL. Within HT, RT was also negatively correlated with MK and GL and tended to be negatively correlated with CW. In addition to being negatively correlated with RT and RR, HT MK was positively correlated with CW, GL, and DMI postpartum. In CL, no correlations were observed for RR, but RT was positively correlated with BW, and MK was positively correlated with DMI postpartum and tended to be positively correlated with GL. Moreover, the overall RT was 39.1 ± 0.48°C and RR was 61 ± 19.5 bpm, which indicates that RR over 61 bpm is an indicator of heat stress in cows during the dry period and can be easily assessed at the cow level. In summary, the more heat load a cow carries in the dry period, the greater the negative effects are on subsequent milk production, which may suggest a threshold for the effects of heat stress. Also, variation among cows within the HT group indicates that cows with longer gestation length have heavier calves, eat more postpartum, and produce more milk, but not as much as CL cows.

8.
Water Res ; 42(15): 4163-71, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18762314

RESUMO

The main objective of this study was to analyze the effectiveness of technologies based on the use of ozone and activated carbon for the removal of nitroimidazoles from water, considering them as model of pharmaceutical compounds. A study was undertaken of the influence of the different operational variables on the effectiveness of each system studied (O(3), O(3)/activated carbon), and on the kinetics involved in each process. Ozone reaction kinetics showed that nitroimidazoles have a low reactivity, with K(O)(3) values <350 M(-1)s(-1) regardless of the nitroimidazole and solution pH considered. However, nitroimidazoles have a high affinity for HO radicals, with radical rate constant (k(HO)) values of around 10(10)M(-1)s(-1). Among the nitroimidazole ozonation by-products, nitrate ions and 3-acetyl-2-oxazolidinone were detected. The presence of activated carbon during nitroimidazole ozonation produces (i) an increase in the removal rate, (ii) a reduction in the toxicity of oxidation by-products, and (iii) a reduction in the concentration of dissolved organic matter. These results are explained by the generation of HO radicals at the O(3)-activated carbon interface.


Assuntos
Carbono/química , Nitroimidazóis/isolamento & purificação , Ozônio/química , Purificação da Água/métodos , Carvão Vegetal/química , Radical Hidroxila/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Nitroimidazóis/química
9.
Water Res ; 40(8): 1717-25, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16597457

RESUMO

A study was conducted on the efficacy of the system based on the simultaneous use of ozone and powdered activated carbon (PAC) in removing sodium dodecylbenzenesulphonate (SDBS) from drinking waters and on the influence of operational parameters (PAC dose, ozone dose and presence of radical scavengers [HCO3-]) on this process. Results obtained showed that low doses of PAC during SDBS ozonation markedly increased the rate of SDBS removal from the medium. These results are due to the combined effect of two processes: (i) SDBS adsorption on the activated carbon surface and (ii) transformation of the dissolved ozone into .OH radicals. At higher ozone and PAC doses, there was a higher rate of SDBS removal from the medium. The presence of HCO3- in the medium reduced the SDBS removal rate of the O3/PAC system. This finding confirms that the presence of PAC during SDBS ozonation favours ozone transformation into .OH radicals. Comparison of the O3/PAC system with systems based on the use of O3 or O3/H2O2 showed that the efficacy of the O3/PAC system to remove SDBS is much greater than that of the traditional oxidation methods. Thus, in the first 5 min of treatment (usual hydraulic retention time), the percentage of SDBS removed was 18% and 30% for the O3 and O3/H2O2 systems, respectively, compared with 70% for the O3/PAC system. SDBS ozonation in surface waters intended for human consumption demonstrated that the O3/PAC approach is the most efficacious of the studied systems, considerably increasing the SDBS removal rate and also reducing the concentration of dissolved organic carbon. Therefore, the results of this study show that the system based on O3/PAC is a highly attractive option for the treatment of drinking water.


Assuntos
Benzenossulfonatos/química , Carbono/química , Ozônio/química , Tensoativos/isolamento & purificação , Água/química , Adsorção , Tamanho da Partícula , Abastecimento de Água
10.
Diabetes ; 34(8): 780-6, 1985 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-4018415

RESUMO

Insulin binding to erythrocytes was sequentially studied in 12 healthy pregnant women during the anabolic (11-22 wk) and the catabolic (31-38 wk) gestational phases. For comparison, we studied 12 nonpregnant subjects at mid-luteal and mid-follicular menstrual phases. Oral glucose tolerance tests were also performed during these studies. There was a progressive worsening of the glucose tolerance from the anabolic to the catabolic phase associated with fasting hypoglycemia and hyperinsulinemia. The worsening of glucose tolerance was accompanied by a progressive increment of insulin secretion. Insulin binding to red blood cells increased progressively from the anabolic to the catabolic phase, due to an increased number of receptors per cell, associated with a reduction in the apparent affinity at the low occupancy levels. We concluded that the insulin resistance of pregnancy was not accompanied by an impaired binding of insulin to its receptors, at least in the RBC. The data suggest that the defect of insulin action lies at a site distal to the receptor.


Assuntos
Eritrócitos/metabolismo , Glucose/metabolismo , Gravidez , Receptor de Insulina/metabolismo , Adulto , Feminino , Fase Folicular , Teste de Tolerância a Glucose , Humanos , Fase Luteal , Primeiro Trimestre da Gravidez , Segundo Trimestre da Gravidez , Terceiro Trimestre da Gravidez , Estudos Prospectivos
11.
Water Res ; 37(8): 1905-11, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12697233

RESUMO

A study was undertaken of the regeneration of three activated carbons exhausted with ortho-chlorophenol. The regeneration process was carried out using liquid water at 623 K and 150 atm in the absence of oxygen. The efficiency of this procedure was analyzed by determining the rate and amount of ortho-chlorophenol adsorbed in successive adsorption-regeneration cycles. The present procedure showed a much greater efficiency than that reported for chemical and/or thermal regeneration. Effects of this regeneration on the adsorption kinetics, adsorption capacity and textural characteristics of the carbon were investigated. The increase in adsorption capacity of the regenerated carbon compared with that of the original carbon seems mainly due to the opening of porosity during the regeneration treatment.


Assuntos
Carbono/análise , Clorofenóis/química , Purificação da Água , Adsorção , Carbono/química , Cinética , Pressão , Temperatura
12.
Med Cutan Ibero Lat Am ; 6(1): 23-7, 1978.
Artigo em Espanhol | MEDLINE | ID: mdl-384110

RESUMO

The case of two brothers affected by alcaptonurie is reported. The activity of the homogenthisycasa enzyme has been determined by the material obtained through percutaneous biopsy. Concentrations of the aminoacids producing fenilalanina and thiroxina in their parents' blood have been investigated, the tests showing lack of liver enzyme and normal concentration of the amount of aminoacids in blood. Some aspects of skin lesion have been briefly reported and methods for treatment presented.


Assuntos
Ocronose/enzimologia , Adulto , Ácido Homogentísico/análise , Humanos , Masculino , Ocronose/genética , Linhagem
13.
Rev Esp Med Nucl Imagen Mol ; 33(5): 280-5, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25066253

RESUMO

OBJECTIVES: To investigate quantitative methods of tumor proliferation using 3'-[(18)F]fluoro-3'-deoxythymidine ([(18)F]FLT) PET in patients with breast cancer (BC), studied before and after one bevacizumab administration, and to correlate the [(18)F]FLT-PET uptake with the Ki67 index. MATERIAL AND METHODS: Thirty patients with newly diagnosed, untreated BC underwent a [(18)F]FLT-PET before and 14 days after bevacizumab treatment. A dynamic scan centered over the tumor began simultaneously with the injection of [(18)F]FLT (385 ± 56 MBq). Image derived input functions were obtained using regions of interest drawn on the left ventricle (LV) and descending aorta (DA). Metabolite corrected blood curves were used as input functions to obtain the kinetic Ki constant using the Patlak graphical analysis (time interval 10-60 min after injection). Maximum SUV values were derived for the intervals 40-60 min (SUV40) and 50-60 min (SUV50). PET parameters were correlated with the Ki67 index obtained staining tumor biopsies. RESULTS: [(18)F]FLT uptake parameters decreased significantly (p<0.001) after treatment: SUV50=3.09 ± 1.21 vs 2.22 ± 0.96; SUV40=3.00 ± 1.18 vs 2.14 ± 0.95, Ki_LV(10-3)=52[22-116] vs 38[13-80] and Ki_DA(10-3)=49[15-129] vs 33[11-98]. Consistency interclass correlation coefficients within SUV and within Ki were high. Changes of SUV50 and Ki_DA between baseline PET and after one bevacizumab dose PET correlated with changes in Ki67 index (r-Pearson=0.35 and 0.26, p=0.06 and 0.16, respectively). CONCLUSIONS: [(18)F]FLT-PET is useful to demonstrate proliferative changes after a dose of bevacizumab in patients with BC. Quantification of tumor proliferation by means of SUV and Ki has shown similar results, but SUV50 obtained better results. A correlation between [(18)F]FLT changes and Ki67 index was observed.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Didesoxinucleosídeos , Radioisótopos de Flúor , Tomografia por Emissão de Pósitrons , Adulto , Idoso , Inibidores da Angiogênese/uso terapêutico , Bevacizumab/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células , Feminino , Humanos , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Tomografia por Emissão de Pósitrons/métodos , Estudos Prospectivos
14.
J Hazard Mater ; 174(1-3): 880-6, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-19815338

RESUMO

The main objective of the present study was to analyze the efficacy of technologies based on ozone and activated carbon in dynamic regime to remove organic micropollutants from waters, using the antibiotic tinidazole (TNZ) as a model compound. Results obtained in static regime show that the presence of activated carbon (GAC) during tinidazole ozonation: (i) increases its removal rate, (ii) reduces oxidation by-product toxicity, and (iii) reduces the concentration of dissolved organic matter. Study of the ozone/activated carbon system in dynamic regime showed that ozonation of tinidazole before the adsorption process considerably improves column performance, increasing the volume of water treated. It was observed that the efficacy of the treatment considerably increased with a shorter contact time between TNZ and O(3) streams before entering the column allowing a much higher volume of TNZ solution to be treated compared with the use of activated carbon alone, and reducing by 75% the amount of activated carbon required per unit of treated water volume. TNZ removal by the O(3)/GAC system is lower in natural waters and especially in wastewaters, than in ultrapure water. The toxicity results obtained during TNZ treatment with O(3)/GAC system showed that toxicity was directly proportional to the concentration of TNZ in the effluent, verifying that oxidation of the organic matter in the natural waters did not increase the toxicity of the system.


Assuntos
Carbono/química , Ozônio/química , Tinidazol/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Cromatografia Líquida de Alta Pressão
16.
J Hazard Mater ; 170(1): 298-305, 2009 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-19464791

RESUMO

The objective of the present study was to analyse the behaviour of activated carbon with different chemical and textural properties in nitroimidazole adsorption, also assessing the combined use of microorganisms and activated carbon in the removal of these compounds from waters and the influence of the chemical nature of the solution (pH and ionic strength) on the adsorption process. Results indicate that the adsorption of nitroimidazoles is largely determined by activated carbon chemical properties. Application of the Langmuir equation to the adsorption isotherms showed an elevated adsorption capacity (X(m)=1.04-2.04 mmol/g) for all contaminants studied. Solution pH and electrolyte concentration did not have a major effect on the adsorption of these compounds on activated carbon, confirming that the principal interactions involved in the adsorption of these compounds are non-electrostatic. Nitroimidazoles are not degraded by microorganisms used in the biological stage of a wastewater treatment plant. However, the presence of microorganisms during nitroimidazole adsorption increased their adsorption on the activated carbon, although it weakened interactions between the adsorbate and carbon surface. In dynamic regime, the adsorptive capacity of activated carbon was markedly higher in surface water and groundwater than in urban wastewaters.


Assuntos
Antibacterianos/isolamento & purificação , Carvão Vegetal/química , Nitroimidazóis/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Bactérias , Recuperação e Remediação Ambiental/métodos , Concentração de Íons de Hidrogênio , Soluções , Purificação da Água/métodos
17.
Environ Sci Technol ; 39(16): 6246-50, 2005 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-16173588

RESUMO

The present study aimed to analyze the behavior of different activated carbons in the adsorption and removal of bisphenol A (2-2-bis-4-hydroxypheniyl propane) from aqueous solutions in order to identify the parameters that determine this process. Two commercial activated carbons and one prepared in our laboratory from almond shells were used; they were texturally and chemically characterized, obtaining the surface area, pore size distribution, mineral matter content, elemental analysis, oxygen surface groups, and pH of the point of zero charge (pH(PZC)), among other parameters. Adsorption isotherms of bisphenol A and adsorption capacities were obtained. The capacity of the carbons to remove bisphenol A was related to their characteristics. Thus, the adsorption of bisphenol A on activated carbon fundamentally depends on the chemical nature of the carbon surface and the pH of the solution. The most favorable experimental conditions for this process are those in which the net charge density of the carbon is zero and the bisphenol A is in molecular form. Under these conditions, the adsorbent-adsorbate interactions that govern the adsorption mechanism are enhanced. Influences of the mineral matter present in the carbon samples and the solution chemistry (pH and ionic strength) were also analyzed. The presence of mineral matter in carbons reduces their adsorption capacity because of the hydrophilic nature of the matter. The presence of electrolytes in the solution favor the adsorption process because of the screening effect produced between the positively charged carbon surface and the bisphenol A molecules, with a resulting increase in adsorbent-adsorbate interactions.


Assuntos
Carbono/química , Estrogênios não Esteroides/isolamento & purificação , Fenóis/isolamento & purificação , Purificação da Água/métodos , Adsorção , Compostos Benzidrílicos , Estrogênios não Esteroides/química , Concentração de Íons de Hidrogênio , Fenóis/química
18.
Arch Biochem Biophys ; 319(2): 519-24, 1995 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-7786037

RESUMO

The conidiation process of Neurospora crassa is characterized by three morphogenetic steps: hyphal adhesion, aerial hyphal formation, and production of conidia. Total protein oxidation and specific enzyme oxidation coincided with an increased oxygen-dependent chemiluminescence and indicated the occurrence of a hyperoxidant state at the onset of all three morphogenetic steps. Oxidation of NAD(P)H and excretion of glutathione disulfide was detected at the start of hyphae adhesion. Here we show that NAD(P)H and glutathione redox imbalance also occurred at the beginning of aerial hyphal growth and just before formation of conidia in the isolated cell structures. An increased loss and oxidation of NAD(P)(H) and glutathione were detected with each morphogenetic transition. These results give further support to our proposal that a hyperoxidant state develops at the start of each of the three morphogenetic processes during N. crassa conidiation.


Assuntos
Neurospora crassa/crescimento & desenvolvimento , Glutationa/metabolismo , NADP/metabolismo , Neurospora crassa/metabolismo , Oxirredução
19.
Microbiology (Reading) ; 140 ( Pt 9): 2391-7, 1994 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7952190

RESUMO

The conidiation process of Neurospora crassa is characterized by three morphogenetic steps: hyphal adhesion, aerial hyphal formation, and production of conidia. Previous data indicated the occurrence of a hyperoxidant state at the onset of all three morphogenetic steps. Because glutamine synthetase (GS) and the biosynthetic glutamate dehydrogenase [GDH(NADP)] enzymes are susceptible to inactivation by reactive oxygen species, we followed these enzyme activities during conidiation and under different physiological conditions and related them to the hyperoxidant states and morphogenesis. Loss of GS activity occurred prior to all three morphogenetic steps, coinciding with an increase in total protein oxidation. Oxidized GS polypeptides were detected during hyphal adhesion. Loss of GDH(NADP) activity also occurred during hyphal adhesion and before aerial hyphal formation; the enzyme polypeptide and activity decreased in the adhered hyphae to low values and no GDH(NADP) was detected in aerial hyphae. The catabolic GDH [GDH(NAD)] behaved in an opposite manner, increasing its activity during hyphal adhesion and aerial hyphae development. These results are discussed with regard to cell differentiation and the conidiation process in N. crassa.


Assuntos
Neurospora crassa/fisiologia , Glutamato Desidrogenase/antagonistas & inibidores , Glutamato-Amônia Ligase/antagonistas & inibidores , NAD/metabolismo , NADP/metabolismo , Neurospora crassa/enzimologia , Neurospora crassa/crescimento & desenvolvimento , Oxirredução , Esporos Fúngicos/fisiologia
20.
J Biol Chem ; 256(11): 5926-30, 1981 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-7240181

RESUMO

Insoluble collagen fibrils were obtained from Cysticercus cellulosae after homogenization and treatment with NaCl/mercaptoethanol solutions and were solubilized after limited pepsin digestion. Solubilized Cysticercus collagen shows two different alpha subunits in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent molecular weight of 100,000 and is readily degraded by bacterial collagenase. The amino acid composition is characteristic of collagen except that it contains no hydroxyproline. Segment long spacing crystallites measuring 280 nm in length were prepared. These segments showed a band pattern different from that of vertebrate and other invertebrate collagens. The denaturation temperature at neutral pH was 35 degrees C and correlated with the total pyrrolidine content as observed for other collagens. An intrinsic viscosity value of 15.3 dl/g was obtained for this collagen. Its possible evolutionary relationship with other collagens is discussed.


Assuntos
Colágeno/isolamento & purificação , Cysticercus/análise , Taenia/análise , Aminoácidos/análise , Animais , Cristalização , Microscopia Eletrônica , Fragmentos de Peptídeos/análise , Conformação Proteica , Desnaturação Proteica , Pele/análise , Viscosidade
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