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1.
Environ Sci Process Impacts ; 23(1): 132-143, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33367373

RESUMO

Nitrogen (N) loss from rice production systems in the form of ammonia (NH3) can be a significant N loss pathway causing significant economic and environmental costs. Yet, data on NH3 fluxes in wetland rice ecosystems are still very scarce which limits the accuracy of national and global NH3 budgets. We measured the NH3 fluxes in situ in a wetland rice field and estimated emission factors (EF) under two soil management systems (i.e. conventional tillage, CT and strip tillage, ST); two residue retention levels (i.e. 15%, LR and 40% crop residue by height, HR); and three N fertilization rates (i.e. 108, 144 and 180 kg N ha-1) in two consecutive years (2019 and 2020). The highest NH3 peaks were observed within the first 3 days after urea application. The mean and cumulative NH3 fluxes significantly increased with the increases in N fertilization rates and were 18.5% and 18.6% higher in ST than in CT in 2020 but not in 2019. Overall, the highest mean NH3 fluxes were in 180 kg N ha-1 coupled with either HR or LR and ST or CT. In 2019, the NH3 EF was unchanged by any treatments. In 2020, the lower EF was in CT coupled with LR (15%) than all other treatment combinations, where ST with HR showed the highest EF (20%). Likewise, the lowest N rate (108 kg N ha-1) in ST had the highest NH3 EF (20%) that was similar to higher N rates (144 and 180 kg N ha-1) in the same tillage treatment and to 180 kg N ha-1 in CT. Our results highlight that NH3 fluxes in rice field particularly the effects of ST correlated with higher soil pH and NH4+ content and lower redox potential. Our results highlight that NH3 fluxes are a potentially large N loss pathway in wetland rice under conventional and decreased soil disturbance regimes.


Assuntos
Amônia , Oryza , Agricultura , Amônia/análise , Ecossistema , Fertilizantes/análise , Nitrogênio/análise , Solo , Áreas Alagadas
2.
Mymensingh Med J ; 29(3): 516-522, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32844788

RESUMO

The surgical procedures of post traumatic posterior urethral stricture and distraction defects range from the extremely simple to the extremely radical. In oral Mucosal Graft Augmented Anastomotic Urethroplasty (OMG AAU) the stricture segment is excised followed by partially re-anastomosis of the dorsal or ventral urethral wall then the reconstruction is completed by placement of oral mucosal graft into the remaining urethral defect. The aim of this study is to determine the impact and assess the effectiveness of this technique, discuss the procedure and outcome and to refine them where found lacking. A prospectively collected review of records was done from September 2010 to April 2019. A total 100 patients with post traumatic urethral stricture and distraction defect were treated by dorsal onlay oral mucosal graft augmented anastomotic urethroplasty by same surgeon in a single centre. All were followed up every 3 and 6 monthly for 1-2 years with uroflowmetry. Retrograde urethrogram/Micturating cysto-urethrogram (RGU/MCU) and cystoscopy were reserved for those who had complained of obstructive symptoms and uroflowmetry evidence of outflow obstruction. The etiology of trauma was road traffic accident (RTA) (69%), falling astride (28%) and traumatic catheterization (3%). Mean excised stricture length was 1.5cm (Range 1.0-2.2). The mean length of dorsal onlay considering excised stricture length and 1cm spatulations was 4.25cm (range 2.0-6.5). The successful recovery was observed in 94% cases. On conclusion the technique of OMG AAU is very easy to do, reliable and has high success rates. This is also the procedure of choice for long segment obliterative strictures. For post traumatic obliterative strictures and distraction defects we strongly recommend the procedure for successful and patient satisfactory outcome.


Assuntos
Procedimentos Cirúrgicos Reconstrutivos , Estreitamento Uretral/cirurgia , Humanos , Masculino , Mucosa Bucal , Estudos Retrospectivos , Resultado do Tratamento , Uretra/cirurgia , Procedimentos Cirúrgicos Urológicos Masculinos
3.
Sci Total Environ ; 610-611: 1029-1037, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-28847096

RESUMO

In the San Francisco Estuary, California, the largest estuary on the Pacific Coast of North America, the frequency and intensity of drought and associated cyanobacteria blooms are predicted to increase with climate change. To assess the impact of water quality conditions on estuarine fish health during successive severe drought years with Microcystis blooms, we performed fish embryo toxicity testing with Delta Smelt and Medaka. Fish embryos were exposed to filtered ambient water collected from the San Francisco Estuary during the Microcystis bloom season in 2014 and 2015, the third and fourth most severe recorded drought years in California. Medaka embryos incubated in filtered ambient waters exhibited high mortality rates (>77%), which was mainly due to bacterial growth. Medaka mortality data was negatively correlated with chloride, and positively correlated with water temperature, total and dissolved organic carbon, and ambient and net chlorophyll a concentration. Delta Smelt embryo mortality rates were lower (<42%) and no prominent seasonal or geographic trend was observed. There was no significant correlation between the Delta Smelt mortality data and water quality parameters. Aeromonas was the dominant bacteria that adversely affected Medaka. The growth of Aeromonas was suppressed when salinity was greater than or equal to 1psu and resulted in a significant reduction in mortality rate. Bacterial growth test demonstrated that the lysate of Microcystis cells enhanced the growth of Aeromonas. Toxin production by Microcystis is a major environmental concern, however, we conclude that dissolved substances released from Microcystis blooms could result in water quality deterioration by promoting growth of bacteria. Furthermore, a distinctive developmental deformity was observed in Medaka during the toxicity tests; somite formation was inhibited at the same time that cardiogenesis occurred and the functional heart was observed to be beating. The exact cause of the embryonic developmental deformity is still unknown.


Assuntos
Secas , Embrião não Mamífero/efeitos dos fármacos , Monitoramento Ambiental/métodos , Estuários , Microcistinas/toxicidade , Microcystis/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Clorofila , Clorofila A , Mudança Climática , Cianobactérias , Proliferação Nociva de Algas , Osmeriformes/embriologia , São Francisco
4.
Mymensingh Med J ; 25(3): 559-63, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27612907

RESUMO

Angiomyolipoma (AML) is a benign tumor commonly found in kidney than extra renal sites. Most of the small renal angiomyolipomas are diagnosed incidentally on ultrasound and other imaging studies. Some renal AMLs present clinically when become very big, giant renal angiomyolipoma. Although almost all cases are benign, a relatively rare variant of epitheloid angiomyolipoma has got malignant potential and can even metastasize. Ultrasonography, CT and MRI scan are usually used for diagnosis of angiomyolipoma with high level of accuracy; even though some lesions may be confused as renal cell carcinoma on imaging studies. Here, a 48 year old man presented with a large intra-abdominal mass preoperatively diagnosed as a case of right renal cell carcinoma and radical nephrectomy was performed. Histopathology revealed epitheloid angiomyolipoma (EAML).


Assuntos
Angiomiolipoma , Carcinoma de Células Renais , Neoplasias Renais , Angiomiolipoma/diagnóstico , Angiomiolipoma/cirurgia , Carcinoma de Células Renais/diagnóstico por imagem , Humanos , Neoplasias Renais/diagnóstico , Neoplasias Renais/cirurgia , Masculino , Pessoa de Meia-Idade , Nefrectomia
5.
Toxicol Rep ; 3: 346-350, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28959555

RESUMO

This study is aimed to assess the heavy metals contamination and health risk in Shrimp (Macrobrachium rosenbergii and Penaeus monodon) collected from Khulna-Satkhira region in Bangladesh. The results showed that the Pb concentrations (0.52-1.16 mg/kg) in all shrimp samples of farms were higher than the recommended limit. The Cd levels (0.05-0.13 mg/kg) in all samples and Cr levels in all farms except tissue content at Satkhira farm were higher than the permissible limits. The individual concentration of Pb, Cd, and Cr between shrimp tissue and shell in all rivers and farms were not statistically significant (P > 0.05). Target hazard quotient (THQ) and hazard index (HI) were estimated to assess the non-carcinogenic health risks. Shrimp samples from all locations under the current study were found to be safe for consumption, the possibility of health risk associated with non-carcinogenic effect is very low for continuous consumption for 30 years.

6.
Avian Pathol ; 43(2): 183-94, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24689433

RESUMO

In Bangladesh, highly pathogenic avian influenza (HPAI) virus subtype H5N1 was first detected in February 2007. Since then the virus has become entrenched in poultry farms of Bangladesh. There have so far been seven human cases of H5N1 HPAI infection in Bangladesh with one death. The objective of the present study was to investigate the molecular evolution of H5N1 HPAI viruses during 2007 to 2012. Partial or complete nucleotide sequences of all eight gene segments of two chicken isolates, five gene segments of a duck isolate and the haemagglutinin gene segment of 18 isolates from Bangladesh were established in the present study and subjected to molecular analysis. In addition, full-length sequences of different gene segments of other Bangladeshi H5N1 isolates available in GenBank were included in the analysis. The analysis revealed that the first introduction of clade 2.2 virus in Bangladesh in 2007 was followed by the introduction of clade 2.3.2.1 and 2.3.4 viruses in 2011. However, only clade 2.3.2.1 viruses could be isolated in 2012, indicating progressive replacement of clade 2.2 and 2.3.4 viruses. There has been an event of segment re-assortment between H5N1 and H9N2 viruses in Bangladesh, where H5N1 virus acquired the PB1 gene from a H9N2 virus. Point mutations have accumulated in Bangladeshi isolates over the last 5 years with potential modification of receptor binding site and antigenic sites. Extensive and continuous molecular epidemiological studies are necessary to monitor the evolution of circulating avian influenza viruses in Bangladesh.


Assuntos
Galinhas/virologia , Patos/virologia , Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Sequência de Aminoácidos , Animais , Bangladesh/epidemiologia , Sequência de Bases , Evolução Molecular , Humanos , Virus da Influenza A Subtipo H5N1/patogenicidade , Influenza Aviária/epidemiologia , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Filogenia , Doenças das Aves Domésticas/epidemiologia , Alinhamento de Sequência/veterinária , Análise de Sequência de DNA/veterinária , Proteínas Virais/genética
7.
Mymensingh Med J ; 21(4): 696-701, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23134920

RESUMO

The use of oral mucous membrane graft onlay urethroplasty represents the most widespread method of bulbar urethral stricture repair. We investigated the short term result of oral mucous membrane graft placed on the ventral surface for management of bulbar urethral stricture. Patients with Bulbar urethral stricture of any length, infection free urinary tract and informed consent for oral mucosa harvesting and urethroplasty were selected for study. We enrolled 108 cases of bulbar urethral stricture patients from January 2004 to July 2009. The mean ± SD preoperative maximum flow rate of 5.2 ± 2.6 ml/sec and mean ± SD PVR 87 ± 58.3 ml were treated by substitution urethroplasty with oral mucous membrane by a single surgical team in a private hospital. Causes of stricture were trauma 26(24.1%), infection 58(53.7%), catheter induced 8(7.4%), post TURP 11(10.2%) and unknown 5(4.6%). Oral mucous membrane was harvested from the cheek or from the inner side of lower lip. Defect of the urethra displayed by longitudinal ventral urethrotomy and the graft was sutured over the edges of the incised urethral mucosa over a 14 Fr latex Foley's catheter. Spongiosum tissue was closed over the graft. Pericatheter urethrogram was performed in all cases to check for the anastomotic leakage and the Catheter was removed after 2 weeks of the procedure. After removal of catheter uroflowmetry & ultrasound scan of bladder were performed to estimate the maximum flow rate and post voidal residue. The patient was followed-up every 3 months with uroflowmetry & ultrasonography. The median (range) age of the patients was 32(21-72) years. Mean follow up period was 36 months (range 12-54). Mean ± SD stricture length was 3.7 ± 2.6 cm. The overall success rate was 91.7%. Mean ± SD flow rate was 23 ± 4.2 ml/sec, mean ± SD post void residue was 25 ± 15.5 ml and patient quality of life (QOL) was excellent in almost all patients. Overall complications were seen in 9(8.3%) cases. Of which, restricture occurred in 6 patients; periurethral fistulae seen in 2 cases and per urethral bleeding in 1 patient. No significant complications were observed at the donor site. Oral numbness and mild discomfort complained by 67.6% patients which were managed by reassurance only. In our experience ventral placement of oral mucous membrane graft along with spongioplasty is a very easy procedure with very encouraging short term result.


Assuntos
Retalhos de Tecido Biológico , Mucosa Bucal/transplante , Estreitamento Uretral/cirurgia , Adulto , Idoso , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Adulto Jovem
8.
Mymensingh Med J ; 21(2): 300-5, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22561775

RESUMO

To evaluate the predictive value of urine cultures in the assessment of ureteral stent colonization and to investigate the frequency of double J stent colonization and stent associated bacteriuria. This observational study was conducted in the department of Urology, Dhaka Medical College Hospital from December 2006 to March 2009. A total of 100 patients (mean age 39.2 ± 9.9 years, range 18-60 years, 69 male and 31 female) needing internal ureteral stent placement for different sorts of urinary tract operations were included in the study. Sterile urine samples were obtained from each patient before stenting and all patients had been given short-term prophylactic antibiotic (5-12 days). On the day of stent removal midstream urine were obtained from all patients for microbiological culture. Stents removed by aseptic precaution. Proximal and distal tip segments (3-5 cm) were also sent for culture. The lowest and highest durations of stenting were 10 and 86 days respectively (median 35 days). Both bacteriuria and bacterial colonization was significantly higher as duration of stenting increases (p=0.045 and p<0.001). E. coli was the most common microorganism isolated from both urine and stent culture. However, colonization rate of stents was much higher (45%) than positive urine cultures (21%) indicating that urine culture is less sensitive to diagnose stent colonization (k-value = 0.49). The study concludes that bacterial colonization significantly increases with indwelling time of stent and sterile culture of urine does not rule out that the stent itself is colonized.


Assuntos
Stents/microbiologia , Urina/microbiologia , Adolescente , Adulto , Contagem de Colônia Microbiana , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Fatores de Tempo , Obstrução Ureteral/terapia , Adulto Jovem
9.
Transbound Emerg Dis ; 59(5): 460-3, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22212904

RESUMO

Since the first outbreak of highly pathogenic H5N1 avian inafluenza (HPAI) in Bangladesh in February 2007, a total of 519 disease events have been reported till 22 October 2011. Partial HA gene sequences of 11 selected H5N1 HPAI isolates of 2007 to 2011 were determined and subjected to phylogenetic analysis. The study revealed a recent introduction of clade 2.3.2 and 2.3.4 viruses into Bangladesh in 2011 in addition to clade 2.2 viruses that had been in circulation since 2007. Clade 2.3.2 virus isolates from Bangladesh are phylogenetically related to the newly designated clade 2.3.2.1 viruses, reported recently from Asia and Eastern Europe.


Assuntos
Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/virologia , Animais , Bangladesh/epidemiologia , Aves , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Aviária/epidemiologia , Dados de Sequência Molecular , Filogenia
10.
Mymensingh Med J ; 20(1): 78-82, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21240167

RESUMO

Adiponectin is an adipocyte derived hormone, a modulator of lipid metabolism and systemic inflammation. It has potential anti-atherogenic property. Adiponectin is present in low concentration in patients with obesity, insulin resistance (IR), Type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD). In this case control study, we studied the association of Serum adiponectin with CHD. Sixty-four subjects were enrolled. Consecutive 31 CHD patients (Group I) and 33 healthy controls (Group II) were included. Serum adiponectin & lipid profile were estimated in all. Serum adiponectin was significantly lower in CHD patients (3.90±2.21µg/ml) in comparison with controls (5.09±2.13µg/ml)(P<0.05). There was no significant difference of any fraction of lipid profile between cases and controls. Significant negative correlation was observed between Serum adiponectin and Serum triacylglyceride (STG) in cases (P<0.01). It may be concluded that low serum adiponectin may have some important role in development of CHD and probably low adiponectin and dyslipidemia are linked in the development of atherosclerosis. Further study is recommended with larger sample size to explore the role of hypoadiponectinemia in the causation of CHD.


Assuntos
Adiponectina/sangue , Doença das Coronárias/sangue , Adulto , Idoso , Índice de Massa Corporal , Estudos de Casos e Controles , Humanos , Lipídeos/sangue , Pessoa de Meia-Idade
11.
Mymensingh Med J ; 19(3): 366-71, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20639828

RESUMO

To assess the frequency of bacterial colonization on internal ureteral stent and stent associated bacteriuria in different periods of indwelling time, a total of 100 patients (mean age 39.2+/-9.9 years, range 18-60 years, 69 male and 31 female) needing internal ureteral stent placement for different sorts of urinary tract operation in the department of Urology, Dhaka Medical College Hospital from December 2006 to May 2008 were included in the study. Sterile urine samples were obtained from each patient before stenting and all patients had been given short-term prophylactic antibiotics (5-12 days). Midstream urine obtained from each patient on the day of stent removal and submitted for microbiological culture. Stent removed by aseptic precautions. Proximal and distal stent tip segments (3-5) were also sent for culture. The median duration of stenting was 35 days (10-86 days). Bacterial colonies were found in 45% of the stent. Colonization rate was 71.4% in stents removed after 6 weeks compared to 33.3% in 4-6 weeks and 23.5% before 4 weeks (p<0.001). Bacteriuria was found only in 21% patients. Escherichia coli was the common organism isolated from both stent and urine. The study concludes that bacterial colonization significantly increases with indwelling time of stent and absence of growth in urine culture does not rule out that the stent itself is colonized.


Assuntos
Infecções Bacterianas/etiologia , Biofilmes , Infecções Relacionadas à Prótese/etiologia , Stents/efeitos adversos , Obstrução Ureteral/terapia , Infecções Urinárias/etiologia , Adolescente , Adulto , Infecções Bacterianas/microbiologia , Infecções Bacterianas/prevenção & controle , Células Cultivadas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Infecções Relacionadas à Prótese/microbiologia , Infecções Relacionadas à Prótese/prevenção & controle , Fatores de Tempo , Infecções Urinárias/microbiologia , Infecções Urinárias/prevenção & controle
12.
Biomed Mater Eng ; 16(3): 223-8, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16518021

RESUMO

Poly(vinyl alcohol) (PVA) can be modified to polymer hydrogels by radiation crosslinking and can be used in different biomedical applications. A study was done on the optimization of ingredients concentration for preparing good quality PVA hydrogels with natural polysaccharides. The synthesized hydrogels were also characterized by measuring the different physical properties e.g. gel fraction, swelling and absorption rate. Besides these, sterility test were also performed. Good quality hydrogels were obtained from PVA and natural polysaccharides solutions with 27 kGy radiation dose. There is an influence of natural polysaccharides on the gel fraction of hydrogel. The increase in the amount of polysaccharide causes a decrease in gel fraction that is decrease in the crosslinking density of PVA hydrogel network. The prepared hydrogels were found to be sterile.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/efeitos da radiação , Hidrogéis/química , Hidrogéis/efeitos da radiação , Polissacarídeos/química , Álcool de Polivinil/química , Álcool de Polivinil/efeitos da radiação , Implantes Absorvíveis , Raios gama , Teste de Materiais , Polissacarídeos/efeitos da radiação , Esterilização/métodos
13.
Biochemistry ; 40(47): 14243-51, 2001 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-11714278

RESUMO

The effects of hemagglutinin (HA) fusion peptide (X-31) on poly(ethylene glycol)- (PEG-) mediated vesicle fusion in three different vesicle systems have been compared: dioleoylphosphatidylcholine (DOPC) small unilamellar vesicles (SUV) and large unilamellar vesicles (LUV) and palmitoyloleoylphosphatidylcholine (POPC) large unilamellar perturbed vesicles (pert. LUV). POPC LUVs were asymmetrically perturbed by hydrolyzing 2.5% of the outer leaflet lipid with phospholipase A(2) and removing hydrolysis products with BSA. The mixing of vesicle contents showed that these perturbed vesicles fused in the presence of PEG as did DOPC SUV, but unperturbed LUV did not. Fusion peptide had different effects on the fusion of these different types of vesicles: fusion was not induced in the absence of PEG or in unperturbed DOPC LUV even in the presence of PEG. Fusion was enhanced in DOPC SUV at low peptide surface occupancy but hindered at high surface occupancy. Finally, fusion was hindered in proportion to peptide concentration in perturbed POPC LUV. Contents leakage assays demonstrated that the peptide enhanced leakage in all vesicles. The peptide enhanced lipid transfer between both fusogenic and nonfusogenic vesicles. Peptide binding was detected in terms of enhanced tryptophan fluorescence or through transfer of tryptophan excited-state energy to membrane-bound diphenylhexatriene (DPH). The peptide had a higher affinity for vesicles with packing defects (SUV and perturbed LUV). Quasi-elastic light scattering (QELS) indicated that the peptide caused vesicles to aggregate. We conclude that binding of the fusion peptide to vesicle membranes has a significant effect on membrane properties but does not induce fusion. Indeed, the fusion peptide inhibited fusion of perturbed LUV. It can, however, enhance fusion between highly curved membranes that normally fuse when brought into close contact by PEG.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/farmacologia , Fusão de Membrana/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Polietilenoglicóis/farmacologia , Proteínas Virais de Fusão/farmacologia , Lipossomos , Peptídeos , Fosfatidilcolinas
14.
Neurochem Res ; 26(4): 401-6, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11495351

RESUMO

The relationship between locomotor activity and monoamine levels in gerbils after single and/or double forebrain ischemic insult was studied. Locomotor hyperactivity was observed after the first ischemic episode, but the gerbils failed to show hyperactivity after the second ischemic episode induced one week later. The monoamine levels were determined in order to clarify the biochemical basis of post-ischemic locomotor hyperactivity. Norepinephrine increased in response to first ischemic episode but remained at normal levels after the second episode of ischemia. Metabolites of dopamine and serotonin increased after both the first and second ischemic insults, which indicates that these monoamines do not play significant roles in post-ischemic locomotor activity. Therefore, increases in norepinephrine after first ischemic insult may play a role in increasing locomotor activity during the period following such an episode.


Assuntos
Monoaminas Biogênicas/metabolismo , Isquemia Encefálica/metabolismo , Atividade Motora , Prosencéfalo/irrigação sanguínea , Animais , Gerbillinae
15.
Biochemistry ; 40(28): 8292-9, 2001 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-11444975

RESUMO

A number of fluorescent probes have been used to follow membrane fusion events, particularly intermixing of lipids. None of them is ideal. The most popular pair of probes is NBD-PE and Rh-PE, in which the fluorescent groups are attached to the lipid headgroups, making them sensitive to changes in the surrounding medium. Here we present a new assay for monitoring lipid transfer during membrane fusion using the acyl chain tagged fluorescent probes BODIPY500-PC and BODIPY530-PE. Like the NBD-PE/Rh-PE assay, this assay is based on fluorescence resonance energy transfer (FRET) between the donor, BODIPY500, and the acceptor, BODIPY530. The magnitude of FRET is sensitive to the probe surface concentration, allowing one to detect movement of probes from labeled to unlabeled vesicles during fusion. The high quantum yield of fluorescence, high efficiency of FRET (R(o) is estimated to be approximately 60 A), photostability, and localization in the central hydrophobic region of a bilayer all make this pair of probes quite promising for detecting fusion. We have compared this and two other lipid mixing assays for their abilities to detect the initial events of poly(ethylene glycol) (PEG)-mediated fusion of small unilamellar vesicles (SUVs). We found that the BODIPY500/530 assay showed lipid transfer rates consistent with those obtained using the DPHpPC self-quenching assay, while lipid mixing rates measured with the NBD-PE/Rh-PE RET assay were significantly slower. We speculate that the bulky labeled headgroups of NBD-PE and especially Rh-PE molecules hamper movement of probes through the stalk between fusing vesicles, and thus reduce the apparent rate of lipid mixing.


Assuntos
Compostos de Boro/química , Corantes Fluorescentes/química , Fusão de Membrana , Lipídeos de Membrana/química , Fosfatidilcolinas/química , Fosfatidiletanolaminas/química , Calibragem , Transferência de Energia , Glicerofosfolipídeos/química , Lipossomos/química , Polietilenoglicóis/química , Rodaminas/química , Espectrometria de Fluorescência/métodos
16.
Fitoterapia ; 72(4): 412-4, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11395266

RESUMO

The flowers of Nyctanthes arbor-tristis showed interesting antibacterial activity against some gram-positive and gram-negative microorganisms (chloroform and ethyl acetate extracts) and significant cytotoxic activity (petroleum ether, chloroform and ethyl acetate extracts).


Assuntos
Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Magnoliopsida , Plantas Medicinais , Animais , Artemia/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia
17.
Neurochem Res ; 26(1): 31-6, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11358279

RESUMO

We have previously reported that ropinirole, a non-ergot dopamine agonist, has neuroprotective effects against 6-hydroxydopamine in mice based on in vivo antioxidant properties such as the glutathione (GSH)-activating effect. In the present study, we determined that the effects of ropinirole on the level of expression of GSH-related enzyme mRNA, these enzymes were shown to regulate GSH contents in the brain. This study focused on the mechanism of GSH enhancement by ropinirole. Striatal GSH contents were significantly increased by 7-day daily administration of ropinirole. Furthermore, the expression levels of gamma-glutamylcysteine synthetase (gamma-GCS), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) mRNA increased following daily injections of ropinirole for 7 days. In addition, ropinirole treatment for 7 days suppressed auto-oxidation in mouse striatal homogenates, in contrast to the vehicle treatment. In conclusion, ropinirole was able to suppress auto-oxidation, most probably by increasing GSH levels due to an increase of GSH synthesis. In addition, it is likely that auto-oxidation was also suppressed by the activation of GSH-regulating enzymes such as GPx, GR, and GST in the mouse striatum. Thus, our results indicate that the GSH-activating effect of ropinirole may render this dopamine agonist beneficial as a neuroprotective drug.


Assuntos
Agonistas de Dopamina/farmacologia , Glutationa/metabolismo , Indóis/farmacologia , Receptores de Dopamina D2/agonistas , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/enzimologia , Corpo Estriado/metabolismo , Esquema de Medicação , Glutationa/genética , Masculino , Camundongos , Camundongos Endogâmicos ICR , Oxirredução/efeitos dos fármacos , RNA Mensageiro/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
18.
Biochemistry ; 40(14): 4340-8, 2001 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-11284690

RESUMO

Poly(ethylene glycol) (PEG)-mediated fusion of phosphatidylcholine model membranes has been shown to mimic the protein-mediated biomembrane process [Lee, J., and Lentz, B. R. (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 9274-9279]. Unlike the simple model membranes used in this earlier study, the lipid composition of fusogenic biomembranes is quite complex. The purpose of this paper was to examine PEG-mediated fusion of highly curved (SUV) and largely uncurved (LUV) membrane vesicles composed of different lipids in order to identify lipid compositions that produce highly fusogenic membranes. Starting with liposomes composed of five lipids with different physical properties, dioleoylphosphatidylcholine (DOPC), dioleoylphosphatidylethanolamine (DOPE), dioleoylphosphatidylserine (DOPS), bovine brain sphingomyelin (SM), and cholesterol (CH), we systematically varied the composition and tested for the extent of PEG-mediated fusion after 5 min of treatment. We found that a vesicle system composed of four lipids, DOPC/DOPE/SM/CH, fused optimally at a 35/30/15/20 molar ratio. Each lipid seemed to play a part in optimizing the membrane for fusion. PE disrupted outer leaflet packing as demonstrated with TMA-DPH lifetime, C(6)-NBD-PC partitioning, and DPH anisotropy measurements, and thus significantly enhanced fusion and rupture, without significantly altering interbilayer approach (X-ray diffraction). An optimal ratio of PC/PE (35/30) produced a balance between fusion and rupture. CH and SM, when present at an optimal ratio of 3/4 in vesicles containing the optimal PC/PE ratio, reduced rupture without significantly reducing fusion. This optimal CH/SM ratio also enhanced outer leaflet packing, suggesting that fusion is dependent not only on outer leaflet packing but also on the properties of the inner leaflet. Addition of CH without SM enhanced rupture relative to fusion, while SM alone reduced both rupture and fusion. The optimal lipid composition is very close to the natural synaptic vesicle composition, suggesting that the synaptic vesicle composition is optimized with respect to fusogenicity.


Assuntos
Bicamadas Lipídicas/química , Lipossomos/química , Fusão de Membrana/efeitos dos fármacos , Lipídeos de Membrana/química , Polietilenoglicóis/farmacologia , Colesterol/química , Difenilexatrieno/análogos & derivados , Difenilexatrieno/química , Polarização de Fluorescência , Corantes Fluorescentes/química , Meia-Vida , Lipídeos de Membrana/análise , Filtros Microporos , Modelos Químicos , Pressão Osmótica , Fosfatidilcolinas/química , Fosfatidiletanolaminas/química , Sonicação , Espectrometria de Fluorescência , Esfingomielinas/química , Propriedades de Superfície , Ultracentrifugação , Difração de Raios X
19.
Fitoterapia ; 71(6): 704-6, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11077181

RESUMO

The extracts of Trapa bispinosa showed interesting antimicrobial activity against Gram-positive and Gram-negative test organisms and significant cytotoxic activity.


Assuntos
Antibacterianos/farmacologia , Artemia/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Animais , Antibacterianos/toxicidade , Humanos , Testes de Sensibilidade Microbiana , Extratos Vegetais/toxicidade
20.
Curr Opin Struct Biol ; 10(5): 607-15, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11042461

RESUMO

Protein machines and lipid bilayers both play central roles in cell membrane fusion, a process crucial to life. Recent results provide clues to how both components function in fusion. Recent observations suggest a common mechanism by which very different fusion machines (from lipid-enveloped viruses and synaptic vesicles) may function to produce compartment-joining pores. This mechanism presumes that fusion proteins act as machines that use stored conformational energy to assemble closely juxtaposed lipid bilayers, bend these to form fusion-competent structures, stabilize unfavorable lipid structures and destabilize a committed intermediate to drive fusion pore formation.


Assuntos
Bicamadas Lipídicas , Fusão de Membrana , Proteínas de Membrana/fisiologia
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