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1.
BMJ Mil Health ; 167(6): 418-423, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32086260

RESUMO

INTRODUCTION: Musculoskeletal injuries to the lower extremities are major factors contributing to drop out from military tasks. The aim of the present study was to determine the incidence of musculoskeletal injuries and the parameters that differentiate between the soldiers who incurred these injuries and those who did not along 14 weeks of an infantry commanders course. METHODS: One-hundred and sixty-eight participants were recruited from an infantry commanders course. The soldiers were tested before (pre), in the middle (middle) and at the end (last) of the course for anthropometric measurements, proprioceptive ability and dynamic postural balance (DPB), and filled out an ankle stability questionnaire (Cumberland Ankle Instability Tool (CAIT). A physiotherapist followed and recorded all musculoskeletal injuries incurred by the participants during the course. RESULTS: Fifty-eight participants out of the 168 (34.5%) reported some pain/injury. Time effects were found for body mass index, DPB asymmetry, DPB in posterior-medial (P-M) direction and proprioception ability. Injury effects were found for DPB asymmetry, DPB in P-M direction, CAIT and proprioception ability. An interaction was found for proprioception ability. The Cox regression showed that the variables that are mostly effecting injuries were pretesting proprioception ability, DPB asymmetry and CAIT. CONCLUSIONS: More than one out of three participants incurred musculoskeletal injuries, with deficits in proprioception ability, DPB and ankle stability in pretesting as major factors contributing to injuries. Further studies should look at the effect of specific exercises such as proprioception, DPB and ankle stability exercises for prevention and treatment of musculoskeletal injuries among combat soldiers.


Assuntos
Instabilidade Articular , Militares , Humanos , Incidência , Equilíbrio Postural , Propriocepção
2.
J R Army Med Corps ; 164(1): 52-57, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28916583

RESUMO

BACKGROUND: Optimal functioning of the lower extremities under repeated movements on unstable surfaces is essential for military effectiveness. Intervention training to promote proprioceptive ability should be considered in order to limit the risk for musculoskeletal injuries. The aim of this study was to assess the effect of a proprioceptive intervention programme on static and dynamic postural balance among Israel Defense Forces combat soldiers. METHODS: Twenty-seven male soldiers, aged 18-20 years, from a physical fitness instructor's course, were randomly divided into two groups matched by age and army unit. The intervention group (INT) underwent 4 weeks of proprioceptive exercises for 10 min daily; the control group underwent 4 weeks of upper body stretching exercises for 10 min daily. All participants were tested pre and postintervention for both static and dynamic postural balance. RESULTS: Significant interaction (condition*pre-post-test*group) was found for static postural balance, indicating that for the INT group, in condition 3 (on an unstable surface-BOSU), the post-test result was significantly better compared with the pretest result (p<0.05). Following intervention, the INT group showed significant correlations between static postural stability in condition 2 (eyes closed) and the dynamic postural stability (length of time walked on the beam following fatigue) (r ranged from 0.647 to 0.822; p<0.05). CONCLUSIONS: The proprioceptive intervention programme for combat soldiers improved static postural balance on unstable surfaces, and improved the correlation between static postural balance in the eyes closed condition and dynamic postural balance following fatigue. Further longitudinal studies are needed to verify the relationship between proprioception programmes, additional weight bearing and the reduction of subsequent injuries in combat soldiers.


Assuntos
Exercício Físico , Militares , Equilíbrio Postural , Propriocepção , Adolescente , Humanos , Israel , Masculino , Distribuição Aleatória , Desempenho Profissional , Adulto Jovem
3.
Int J Sports Med ; 36(13): 1093-9, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26332901

RESUMO

This study sought to determine whether textured insoles inserted in the sports shoes of young dancers improved their inversion and eversion ankle movement discrimination. 26 ballet dancers (14 female, 12 male) from the Australian Ballet School, ages 14-19 years, were divided into 2 groups according to sex and class levels. During the first 4 weeks, the first intervention group (GRP1) was asked to wear textured insoles in their sports shoes during non-class periods, and the second intervention group (GRP2) followed standard practice. In the next 4 weeks, GRP2 was asked to wear the textured insoles and GRP1 did not wear the textured insoles. Participants were tested pre-intervention, after 4 weeks, and at 8 weeks for both inversion and eversion ankle discrimination. In both inversion and eversion testing positions, interaction was found between the 2 groups and the 3 testing times (p<0.001), with significant differences between the first testing and the second testing (p=0.038 and p=0.019, respectively), and between the third testing and the second testing (p=0.003 and p=0.029, respectively). In conclusion, the stimulation to the proprioceptive system arising from textured insoles worn for 4 weeks was sufficient to improve the ankle proprioception of ballet dancers, in both inversion and eversion movements.


Assuntos
Articulação do Tornozelo/fisiologia , Dança , Propriocepção/fisiologia , Sapatos , Adolescente , Austrália , Feminino , Humanos , Masculino , Movimento , Adulto Jovem
4.
Fungal Genet Biol ; 79: 118-24, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26092798

RESUMO

Understanding the cellular organization and biology of fungal pathogens requires accurate methods for genomic integration of mutant alleles or fluorescent fusion-protein constructs. In Zymoseptoria tritici, this can be achieved by integrating of plasmid DNA randomly into the genome of this wheat pathogen. However, untargeted ectopic integration carries the risk of unwanted side effects, such as altered gene expression, due to targeting regulatory elements, or gene disruption following integration into protein-coding regions of the genome. Here, we establish the succinate dehydrogenase (sdi1) locus as a single "soft-landing" site for targeted ectopic integration of genetic constructs by using a carboxin-resistant sdi1(R) allele, carrying the point-mutation H267L. We use various green and red fluorescent fusion constructs and show that 97% of all transformants integrate correctly into the sdi1 locus as single copies. We also demonstrate that such integration does not affect the pathogenicity of Z. tritici, and thus the sdi1 locus is a useful tool for virulence analysis in genetically modified Z. tritici strains. Furthermore, we have developed a vector which facilitates yeast recombination cloning and thus allows assembly of multiple overlapping DNA fragments in a single cloning step for high throughput vector and strain generation.


Assuntos
Ascomicetos/genética , Loci Gênicos , Genética Microbiana/métodos , Biologia Molecular/métodos , Mutagênese Insercional/métodos , Recombinação Genética , Expressão Gênica , Succinato Desidrogenase/genética
5.
Int J Sports Med ; 36(1): 67-74, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25144433

RESUMO

Very little is known about the relationship between proximal joint alignment and hallux valgus among young dancers. This study sought to determine the extent to which spinal and lower extremity alignments are involved in hallux valgus, and to identify predicting variables for its development in young dancers. A group of 1336 young female dancers aged 8-16 years, and 226 control participants of the same age cohort were screened for the presence of hallux valgus, body physique characteristics, joint range of motion, and anatomical anomalies. Hallux valgus was common in the 2 young female populations studied. Among the dancers, 40.0% had bilateral hallux valgus and 7.3% unilateral. Among the controls, 32.3% had bilateral and 1.8% unilateral hallux valgus (χ2=8.27, df=1, p=0.004). Following logistic regression analysis, age (OR=1.028, 95% CI=0.968-1.091), genu varum (OR=1.514; CI=1.139-2.013) and scoliosis (OR=2.089; CI=1.113-3.921) were found to be significant predicting factors for hallux valgus in the dancer group, whereas in the control group, the predicting factors were age (OR=0.911, 95% CI=0.801-1.036) and ankle plantar flexion range of motion (OR=0.972; CI=0.951-0.992). In conclusion, it was found that spinal deformity, lower extremity alignment, and joint range of motion are strongly related to hallux valgus.


Assuntos
Dança/lesões , Hallux Valgus/fisiopatologia , Articulação do Dedo do Pé/fisiopatologia , Adolescente , Fatores Etários , Articulação do Tornozelo/fisiologia , Criança , Dança/fisiologia , Feminino , Articulações do Pé/fisiologia , Articulação do Quadril/fisiologia , Humanos , Postura , Amplitude de Movimento Articular , Escoliose/fisiopatologia , Coluna Vertebral/fisiologia
6.
Int J Sports Med ; 35(3): 238-44, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23900897

RESUMO

The aim of the present study was to characterize the injuries of young dancers attending Centres for Advanced Training. 806 dancers, ages 10-18 years responded to surveys regarding their biological profile, dance experience and injury history, and were examined for their anthropometric profile. Of the 806 dancers, 347 reported an injury. Based on 4 age groups, the total hours of practice per week increased significantly with increasing age. Incidence of injuries per 1000 h of dance practice for dancers ages 11-12 were found to be significantly higher compared to the incidence for dancers ages 13-18 (p<0.05). Foot and ankle and other lower extremities were the most common injury location, and muscle injuries were the most common type of injury. Total months in CAT training (OR=1.044, 95% CI=1.014-1.075) and hours per week in creative style practice (OR=1.282, 95% CI=1.068-1.539) were found to be significantly associated with injuries. In conclusion, both young and mature dancers are exposed to extensive risk of injury. The intensity of training (such as number of months and number of hours of training per week) is important factor that should be taken into account in order to decrease future injuries among young dancers.


Assuntos
Dança/lesões , Adolescente , Distribuição por Idade , Antropometria , Traumatismos em Atletas/epidemiologia , Criança , Feminino , Humanos , Incidência , Extremidade Inferior/lesões , Masculino , Menarca , Músculo Esquelético/lesões , Educação Física e Treinamento , Prevalência , Fatores de Risco , Distribuição por Sexo , Fatores de Tempo , Reino Unido/epidemiologia
7.
Int J Sports Med ; 33(7): 561-6, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22562733

RESUMO

The aim of the present study was to determine the association between joint range of motion (ROM) and patellofemoral pain syndrome (PFPS) in young female dancers. The study population included 1 359 female dancers, aged 8-20 years. All dancers were clinically examined for current PFPS, and their joint ROM was measured at the lumbar spine and the lower extremities. 321 of the 1 359 dancers (23.6%) experienced PFPS. Prevalence of the syndrome increased with the dancer's age (p<0.001). Dancers with hypo ROM in hip external rotation, ankle plantar-flexion, ankle/foot pointe, hip abduction, hip extension, and limited hamstrings and lumbar spine were significantly less prone to developing PFPS compared to dancers with average ROM: 19.2% vs. 26.2% (p=0.014); 13.7% vs. 26.1% (p<0.001); 12.2% vs. 26.2% (p<0.001); 10.0% vs. 25.3% (p<0.001); 12.6% vs. 24.2% (p<0.001); and 9.3% vs. 28.2% (p<0.001), respectively. The group with the smallest prevalence of PFPS (10.2%) manifested restricted ROM at both the hip and ankle/foot joints. Dancers with decreased hip and ankle/foot joints ROM are less prone to develop PFPS. When making an association between joint ROM and injuries, not only the ROM at the targeted joint should be considered, but also the ROM at neighboring joints.


Assuntos
Dança/lesões , Articulação Patelofemoral/patologia , Síndrome da Dor Patelofemoral/etiologia , Adolescente , Fatores Etários , Criança , Feminino , Articulações do Pé/patologia , Articulação do Quadril/patologia , Humanos , Prevalência , Amplitude de Movimento Articular , Rotação , Adulto Jovem
8.
Endocrinology ; 150(5): 2334-41, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19116339

RESUMO

We have shown previously that Ser10 phosphorylation of histone H3 occurs in rat pinealocytes after stimulation with norepinephrine (NE) and that histone modifications such as acetylation appear to play an important role in pineal gene transcription. Here we report the nocturnal phosphorylation of a Ser10 histone H3 kinase, Aurora C, in the rat pineal gland. The time profile of this phosphorylation parallels the increase in the level of phospho-Ser10 histone H3. Studies with cultured pinealocytes indicate that Aurora C phosphorylation is induced by NE and this induction can be blocked by cotreatment with propranolol or KT5720, a protein kinase A inhibitor. Moreover, only treatment with dibutyryl cAMP, but not other kinase activators, mimics the effect of NE on Aurora C phosphorylation. These results indicate that Aurora C is phosphorylated primarily by a beta-adrenergic/protein kinase A-mediated mechanism. Treatment with an Aurora C inhibitor reduces the NE-induced histone H3 phosphorylation and suppresses the NE-stimulated induction of arylalkylamine N-acetyltransferase (AA-NAT), the rhythm-controlling enzyme of melatonin synthesis, and melatonin production. The effects of Aurora C inhibitors on adrenergic-induced genes in rat pinealocytes are gene specific: inhibitory for Aa-nat and inducible cAMP repressor but stimulatory for c-fos. Together our results support a role for the NE-stimulated phosphorylation of Aurora C and the subsequent remodeling of chromatin in NE-stimulated Aa-nat transcription. This phenomenon suggests that activation of this mitotic kinase can be induced by extracellular signals to participate in the transcriptional induction of a subset of genes in the rat pineal gland.


Assuntos
Ritmo Circadiano/fisiologia , Histonas/genética , Histonas/metabolismo , Norepinefrina/farmacologia , Glândula Pineal/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/fisiologia , Animais , Aurora Quinases , Células Cultivadas , Ritmo Circadiano/genética , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/fisiologia , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Especificidade de Órgãos/efeitos dos fármacos , Especificidade de Órgãos/genética , Fosforilação/efeitos dos fármacos , Glândula Pineal/efeitos dos fármacos , Protamina Quinase/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Ratos , Ratos Sprague-Dawley
9.
Endocrinology ; 148(10): 4592-600, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17628002

RESUMO

In this study we investigated the effect of histone acetylation on the transcription of adrenergic-induced genes in rat pinealocytes. We found that treatment of pinealocytes with trichostatin A (TSA), a histone deacetylase inhibitor, caused hyperacetylation of histone H3 (H3) Lys14 at nanomolar concentrations. Hyperacetylation of H3 was also observed after treatment with scriptaid, a structurally unrelated histone deacetylase inhibitor. The effects of TSA and scriptaid were inhibitory on the adrenergic induction of arylalkylamine-n-acetyltransferase (aa-nat) mRNA, protein, and enzyme activity, and on melatonin production. TSA at higher concentrations also inhibited the adrenergic induction of mapk phosphatase-1 (mkp-1) and inducible cAMP early repressor mRNAs. In contrast, the effect of TSA on the norepinephrine induction of the c-fos mRNA was stimulatory. Moreover, the effect of TSA on adrenergic-induced gene transcription was dependent on the time of its addition; its effect was only observed during the active phase of transcription. Chromatin immunoprecipitation with antibodies against acetylated Lys14 of H3 showed an increase in DNA recovery of the promoter regions of aa-nat, mkp-1, and c-fos after treatment with TSA. Together, our results demonstrate that histone acetylation differentially influences the transcription of adrenergic-induced genes, an enhancing effect for c-fos but inhibitory for aa-nat, mkp-1, and inducible cAMP early repressor. Moreover, both inhibitory and enhancing effects appear to be mediated through specific modification of promoter-bound histones during gene transcription.


Assuntos
Adrenérgicos/farmacologia , Histonas/metabolismo , Glândula Pineal/metabolismo , Transcrição Gênica/efeitos dos fármacos , Acetilação , Agonistas alfa-Adrenérgicos/administração & dosagem , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Arilalquilamina N-Acetiltransferase/antagonistas & inibidores , Arilalquilamina N-Acetiltransferase/genética , Arilalquilamina N-Acetiltransferase/metabolismo , Proteínas de Ciclo Celular/genética , Células Cultivadas , Modulador de Elemento de Resposta do AMP Cíclico/genética , Esquema de Medicação , Fosfatase 1 de Especificidade Dupla , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacologia , Inibidores de Histona Desacetilases , Ácidos Hidroxâmicos/administração & dosagem , Ácidos Hidroxâmicos/farmacologia , Hidroxilaminas/farmacologia , Proteínas Imediatamente Precoces/genética , Melatonina/biossíntese , Norepinefrina/administração & dosagem , Norepinefrina/farmacologia , Fosfoproteínas Fosfatases/genética , Glândula Pineal/citologia , Proteína Fosfatase 1 , Proteínas Tirosina Fosfatases/genética , Proteínas Proto-Oncogênicas c-fos/genética , Quinolinas/farmacologia , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/metabolismo , Ratos
10.
Homo ; 56(1): 69-74, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15901119

RESUMO

This study uses metrical characteristics of the patella to derive population specific equations for sex determination in South Africa. Six measurements were taken from 120 normal and undamaged left patellae in a sample of known race, equally distributed by sex, obtained from the Raymond A Dart collection of human skeletons. These data were subjected to discriminant analysis. Maximum height and maximum breadth were selected in the stepwise analysis with an average accuracy of 83% in correct sex classification. Four functions were derived from the direct analysis with a range of average accuracy between 77% and 85%. While most individual variables showed high misclassification rates and may not be useful on their own, maximum height and maximum breadth have an average accuracy of 85 and 79%, respectively.


Assuntos
Patela/anatomia & histologia , Caracteres Sexuais , População Branca , Feminino , Humanos , Masculino , Valores de Referência , África do Sul
12.
J Comp Pathol ; 119(4): 467-72, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9839207

RESUMO

Immunohistochemical evaluation of equine tissue necessitates the use of antibodies reactive with cells from a heterogeneous population. Lymphoid tissues from 12 horses were fixed in Bouin's fluid, ethanol or formalin and examined for immunohistochemical reactivity with anti-equine and anti-human monoclonal antibodies (MAbs) specific for MHC Class II antigens, T and B lymphocytes, and macrophages. Only a few of the anti-equine MAbs tested were reactive with fixed, paraffin wax-embedded tissue. Anti-human MAbs expanded the desired range of reactivity and increased the consistency in different animals. The anti-equine MAbs conferred species specificity and anti-human MAbs provided an increased spectrum of reactivity.


Assuntos
Anticorpos Monoclonais/metabolismo , Especificidade de Anticorpos/imunologia , Cavalos/imunologia , Imuno-Histoquímica , Ácido Acético/imunologia , Animais , Linfócitos B/imunologia , Etanol/imunologia , Formaldeído/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , Linfonodos/imunologia , Tonsila Palatina/imunologia , Picratos/imunologia , Linfócitos T/imunologia , Fixação de Tecidos
13.
Appl Environ Microbiol ; 58(1): 426-8, 1992 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16348638

RESUMO

An anaerobic, freshwater enrichment grew with either nitrate or selenate as an electron acceptor. With both ions present, nitrate reduction preceded selenate reduction. An isolate from the enrichment grew on either ion, but the presence of nitrate precluded the reduction of selenate. Stock cultures of denitrifiers grew anaerobically on nitrate but not on selenate.

14.
J Bacteriol ; 173(22): 7324-9, 1991 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1938924

RESUMO

Pure cultures of the symbiotic cyanobacterium-bryophyte association with Anthoceros punctatus were reconstituted by using Nostoc sp. strain UCD 7801 or its 3-(3,4-dichlorophenol)-1,1-dimethylurea (DCMU)-resistant mutant strain, UCD 218. The cultures were grown under high light intensity with CO2 as the sole carbon source and then incubated in the dark to deplete endogenous reductant pools before measurements of nitrogenase activities (acetylene reduction). High rates of light-dependent acetylene reduction were obtained both before starvation in the dark and after recovery from starvation, regardless of which of the two Nostoc strains was reconstituted in the association. Rates of acetylene reduction by symbiotic tissue with the wild-type Nostoc strain decreased 99 and 96% after 28 h of incubation in the dark and after reexposure to light in the presence of 5 microM DCMU, respectively. Supplementation of the medium with glucose restored nitrogenase activity in the dark to a rate that was 64% of the illuminated rate. In the light and in the presence of 5 microM DCMU, acetylene reduction could be restored to 91% of the uninhibited rate by the exogenous presence of various carbohydrates. The rate of acetylene reduction in the presence of DCMU was 34% of the uninhibited rate of tissue in association with the DCMU-resistant strain UCD 218. This result implies that photosynthates produced immediately by the cyanobacterium can supply at least one-third of the reductant required for nitrogenase activity on a short-term basis in the symbiotic association. However, high steady-state rates of nitrogenase activity by symbiotic Nostoc strains appear to depend on endogenous carbohydrate reserves, which are presumably supplied as photosynthate from both A. punctatus tissue and the Nostoc strain.


Assuntos
Cianobactérias/fisiologia , Fixação de Nitrogênio , Fenômenos Fisiológicos Vegetais , Acetileno/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/metabolismo , Escuridão , Diurona/farmacologia , Cinética , Luz , Nitrogenase/metabolismo , Oxirredução , Plantas/efeitos dos fármacos , Simbiose
15.
Appl Environ Microbiol ; 57(2): 615-7, 1991 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-2014995

RESUMO

Dissimilatory in situ selenate reduction to elemental selenium in sediments from irrigated agricultural drainage regions of western Nevada was measured at ambient Se oxyanion concentrations. Selenate reduction was rapid, with turnover rate constants ranging from 0.04 to 1.8 h-1 at total Se concentrations in pore water of 13 to 455 nM. Estimates of removal rates of selenium oxyanions were 14.38, and 155 mumol m-2 day-1 for South Lead Lake, Massie Slough, and Hunter Drain, respectively.


Assuntos
Agricultura , Bactérias/metabolismo , Compostos de Selênio , Selênio/metabolismo , Microbiologia da Água , Inativação Metabólica , Cinética , Nevada , Oxirredução , Ácido Selênico , Selênio/farmacocinética
16.
Appl Environ Microbiol ; 56(11): 3550-7, 1990 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16348359

RESUMO

We measured potential rates of bacterial dissimilatory reduction of SeO(4) to Se in a diversity of sediment types, with salinities ranging from freshwater (salinity = 1 g/liter) to hypersaline (salinity = 320 g/liter and with pH values ranging from 7.1 to 9.8. Significant biological selenate reduction occurred in all samples with salinities from 1 to 250 g/liter but not in samples with a salinity of 320 g/liter. Potential selenate reduction rates (25 nmol of SeO(4) per ml of sediment added with isotope) ranged from 0.07 to 22 mumol of SeO(4) reduced liter h. Activity followed Michaelis-Menten kinetics in relation to SeO(4) concentration (K(m) of selenate = 7.9 to 720 muM). There was no linear correlation between potential rates of SeO(4) reduction and salinity, pH, concentrations of total Se, porosity, or organic carbon in the sediments. However, potential selenate reduction was correlated with apparent K(m) for selenate and with potential rates of denitrification (r = 0.92 and 0.81, respectively). NO(3), NO(2), MoO(4), and WO(4) inhibited selenate reduction activity to different extents in sediments from both Hunter Drain and Massie Slough, Nev. Sulfate partially inhibited activity in sediment from freshwater (salinity = 1 g/liter) Massie Slough samples but not from the saline (salinity = 60 g/liter) Hunter Drain samples. We conclude that dissimilatory selenate reduction in sediments is widespread in nature. In addition, in situ selenate reduction is a first-order reaction, because the ambient concentrations of selenium oxyanions in the sediments were orders of magnitude less than their K(m)s.

17.
Biochem Int ; 21(6): 1043-50, 1990 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-1964378

RESUMO

A number of sulphydryl reagents inhibit AChE of Torpedo california with pseudo-first-order kinetics, and inhibition can be retarded by quaternary ligands which bind at either the catalytic or peripheral anionic binding sites. Colorimetric determination with one of the inhibitory sulphydryl agents, 5,5'-dithiobis (2-nitrobenzoic acid), reveals the presence of a single thiol group per catalytic subunit; our data thus suggest that inhibition is achieved by reaction with the single free sulphydryl group of Cys231.


Assuntos
Inibidores da Colinesterase , Reagentes de Sulfidrila/farmacologia , Torpedo/metabolismo , 4-Cloromercuriobenzenossulfonato/farmacologia , Animais , Etilmaleimida/farmacologia , Cinética , Ligantes , Paraoxon/farmacologia , Compostos de Quinolínio/farmacologia
18.
J Bacteriol ; 171(11): 6227-33, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2509431

RESUMO

The cyanobacterium Nostoc sp. strain UCD 7801, immediately after separation from pure cultures of a reconstituted symbiotic association with the bryophyte Anthoceros punctatus, exhibited a rate of light-dependent CO2 fixation that was eightfold lower than that measured in the free-living growth state. Ribulose bisphosphate carboxylase/oxygenase (RuBPC/O) specific activity was also eightfold lower in cell extracts of symbiotic strain 7801 relative to that in free-living cultures. The in vitro activity from symbiotic strain 7801 could not be increased by incubation under the standard RuBPC/O activation conditions. Polyclonal antibodies against the RuBPC/O large subunit were used in an enzyme-linked immunosorbent assay to determine that RuBPC/O accounted for 4.3 and 5.2% of the total protein in cell extracts of strain 7801 grown in symbiotic and free-living states, respectively. The results imply that the regulation of RuBPC/O activity in the symbiotic growth state is by a posttranslational mechanism rather than by an alteration in RuBPC/O protein synthesis. The amount of carboxyarabinitol bisphosphate required to irreversibly inhibit RuBPC/O activity of sybiotic cell extracts was 80% of that required for extracts of free-living cultures. This result indicates that any covalent modification of RuBPC/O in symbiotically associated Nostoc cells did not interfere with the ribulose bisphosphate binding site, since inactive enzyme also bound carboxyarabinitol bisphosphate.


Assuntos
Cianobactérias/metabolismo , Fotossíntese , Fenômenos Fisiológicos Vegetais , Ribulose-Bifosfato Carboxilase/metabolismo , Western Blotting , Dióxido de Carbono/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/fisiologia , Diurona/farmacologia , Resistência a Medicamentos , Ensaio de Imunoadsorção Enzimática , Cinética , Luz , Substâncias Macromoleculares , Peso Molecular , Ribulose-Bifosfato Carboxilase/isolamento & purificação , Simbiose
19.
Biochem Pharmacol ; 38(19): 3157-68, 1989 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-2818617

RESUMO

Homologous pairs of non-aged and aged pyrene-containing phosphoryl conjugates of chymotrypsin were prepared in order to characterize by NMR and optical spectroscopy putative differences in the conformation of non-aged and aged organophosphoryl conjugates of serine hydrolases. Pyrenebutyl-O-P(O)(OC2H5)F and pyrenebutyl-O-P(O)(OC2H5)Cl were used to obtain the non-aged form pyrenebutyl-O-P(O)(OC2H5)-Cht, whereas pyrenebutyl-O-P(O)Cl2, pyrenebutyl-O-P(O)(p-nitrophenoxy)Cl, and pyrenebutyl-O-P(O)(p-nitrophenoxy)2 were used to produce the aged conjugate pyrenebutyl-O-P(O)(O )-Cht. These ligands bind covalently to the active site of serine hydrolases. The absorption spectra of both the non-aged and aged conjugates fitted approximately a 1:1 stoichiometry of bound organophosphate and enzyme in the non-aged and aged conjugates. Pyrenebutyl-O-P(O)(OC2H5)-Cht could be reactivated by pyridine-3-aldoxime methiodide, whereas no reactivation was observed for the similarly treated pyrenebutyl-O-P(O)(O-)-Cht. The 31P-NMR and reactivation data taken together strongly support the hypothesis that the aged form of the OP-Cht conjugate contains a P--O- bond. These results provide a partial interpretation for the known resistance of the aged conjugates of serine hydrolases to reactivation.


Assuntos
Quimotripsina/antagonistas & inibidores , Compostos Organofosforados/síntese química , Quimotripsina/análise , Quimotripsina/síntese química , Remoção de Radical Alquila , Ativação Enzimática , Fluorescência , Espectroscopia de Ressonância Magnética , Compostos Organofosforados/análise , Compostos Organofosforados/farmacologia , Conformação Proteica , Pirenos/análise
20.
Biochemistry ; 28(3): 1248-53, 1989 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-2713362

RESUMO

Homologous aged and nonaged fluorescent organophosphorus conjugates of alpha-chymotrypsin (Cht) were used in a comparative spectroscopic study of the conformation of their active sites, employing the pyrene group as the fluorescent probe. Steady-state fluorescence measurements showed that the quantum yield of the pyrene probe which is stoichiometrically attached to the active site is ca. 20% lower in the aged conjugate, pyrenebutyl-O-P(O)(O-)-Cht (PBP-Cht), than in the nonaged conjugate, pyrenebutyl-O-P-(O)(OC2H5)-Cht (PBEP-Cht). Furthermore, fluorescence decay data indicate that quenching is dynamic and is not caused by oxygen. These data, together with collisional quenching data, imply that quenching originates in an internal interaction of the fluorophore with a group within the protein. Thus, interaction of the pyrene moiety with the polypeptide chain is significantly stronger in the aged than in the nonaged conjugate, implying a different orientation of the fluorophore with respect to the protein. Circular dichroism measurements, which reflect the asymmetry of the bound pyrene in the ground state, as well as circularly polarized luminescence studies, which reflect its asymmetry in the excited state, also show that the relative configuration of the pyrene moiety and the polypeptide chain is significantly altered upon aging. Aged conjugates obtained by use of various fluorescenct organophosphates [pyrenebutyl-O-P(O)Cl2, pyrenebutyl-O-P(O)(p-nitrophenoxy)Cl, pyrenebutyl-O-P(O)(p-nitrophenoxy)2] exhibit similar spectroscopic features, thus substantiating the hypothesis that instantaneous aging, by use of pyrenebutyl-O-P(O)Cl2, and dynamic aging, by gradual removal of an aryloxy group, yield a similar product. This finding provides strong support for the formation of a P-O- moiety in the aged conjugates, since the only expected common product of the two processes is PB-O-P(O)(O-)-Cht. Formation of excimers of the pyrene-containing organophosphorylchymotrypsin conjugates at concentrations above 3 X 10(-6) M is also reported.


Assuntos
Quimotripsina/metabolismo , Compostos Organofosforados/metabolismo , Pirenos/metabolismo , Dicroísmo Circular , Ligação Proteica , Conformação Proteica , Espectrofotometria , Relação Estrutura-Atividade
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