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1.
Int J Prison Health ; 2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36422644

RESUMO

PURPOSE: Rates of self-harm are elevated in prison, and there is limited evidence to support the efficacy of brief risk screening at reception to predict and prevent self-harm. This study aims to examine the predictive validity of the self-harm/suicide screening items embedded in a prison mental health screening tool from two key domains strongly associated with risk: previous suicidal/self-harm behaviour, and recent ideation. DESIGN/METHODOLOGY/APPROACH: A sample of men and women were screened on entry to prison, with eight screening items covering the two key domains of risk. Follow-up data on self-harm incidents were collected for 12 months post-screening. The predictive validity of individual screening items, item combinations and cumulative screening score was examined for the overall sample and for men and women separately. FINDINGS: Individual screening items across the two domains were all strongly associated with self-harm in the follow-up period, with odds ratios varying from 2.34 to 9.24. The predictive validity of both individual items, item scores and item combinations demonstrated high specificity but low to moderate sensitivity, and modest area under the curves (AUCs). Predictive validity was generally better for men than women; however, differences were not statistically significant. PRACTICAL IMPLICATIONS: Identifying those at risk of self-harm in prisons remains challenging and brief universal screening at prison entry should be only one component of a broader prison risk assessment and management strategy. ORIGINALITY/VALUE: To the best of the authors' knowledge, this study is one of very few to prospectively examine self-harm behaviour following risk screening. Predictive validity was examined in a representative sample of individuals in custody, and for men and women separately.

2.
Diagnostics (Basel) ; 12(9)2022 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-36140656

RESUMO

Body composition, including sarcopenia, adipose tissue, and myosteatosis, is associated with unfavorable clinical outcomes in patients with coronavirus disease (COVID-19). However, few studies have identified the impact of body composition, including pre-existing risk factors, on COVID-19 mortality. Therefore, this study aimed to evaluate the effect of body composition, including pre-existing risk factors, on mortality in hospitalized patients with COVID-19. This two-center retrospective study included 127 hospitalized patients with COVID-19 who underwent unenhanced chest computed tomography (CT) between February and April 2020. Using the cross-sectional CT images at the L2 vertebra level, we analyzed the body composition, including skeletal muscle mass, visceral to subcutaneous adipose tissue ratio (VSR), and muscle density using the Hounsfield unit (HU). Of 127 patients with COVID-19, 16 (12.6%) died. Compared with survivors, non-survivors had low muscle density (41.9 vs. 32.2 HU, p < 0.001) and high proportion of myosteatosis (4.5 vs. 62.5%, p < 0.001). Cox regression analyses revealed diabetes (hazard ratio [HR], 3.587), myosteatosis (HR, 3.667), and a high fibrosis-4 index (HR, 1.213) as significant risk factors for mortality in patients with COVID-19. Myosteatosis was associated with mortality in hospitalized patients with COVID-19, independent of pre-existing prognostic factors.

3.
Diagnostics (Basel) ; 11(6)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207587

RESUMO

Adipose tissue and skeletal muscle is associated with non-alcoholic fatty liver disease (NAFLD). This study evaluates the association between body composition and histologic severity in patients with NAFLD. Using the cross-sectional CT images at the level of L3 vertebra and the histologic findings of 178 patients with biopsy-proven NAFLD, we analyzed the correlation of the histologic findings to the skeletal muscle index (SMI), subcutaneous adipose tissue index (SATI), and visceral adipose tissue index (VATI), which is defined as the body composition area (cm2) by height squared (m2). The clinical and laboratory features with body composition were analyzed to determine the risk factors for advanced fibrosis. The VATI significantly increased in severe non-alcoholic steatohepatitis (NASH) or advanced fibrosis. In addition, the VATI was correlated with the NAFLD activity score (NAS) and the fibrosis stage. In multivariate analyses, age (odds ratio (OR), 1.09; 95% confidence interval (CI), 1.02-1.19; p = 0.025), severe NASH (OR, 8.66; 95% CI, 2.13-46.40; p = 0.005), and visceral adiposity (OR, 6.77; 95% CI, 1.81-29.90; p = 0.007) were independently associated with advanced fibrosis in patients with NAFLD. Visceral adiposity is correlated with the histologic severity of NAFLD, which is independently associated with advanced fibrosis.

4.
Int J Mol Sci ; 22(5)2021 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-33673727

RESUMO

In this study, synthetic allomelanin was prepared from wild-type Streptomyces glaucescens and recombinant Escherichia coli BL21(DE3) strains. S. glaucescens could produce 125.25 ± 6.01 mg/L of melanin with a supply of 5 mM caffeic acid within 144 h. The ABTS radical scavenging capacity of S. glaucescens melanin was determined to be approximately 7.89 mg/mL of IC50 value, which was comparable to L-tyrosine-based eumelanin. The isolated melanin was used in cotton fabric dyeing, and the effect of copper ions, laccase enzyme treatment, and the dyeing cycle on dyeing performance was investigated. Interestingly, dyeing fastness was greatly improved upon treatment with the laccase enzyme during the cotton dyeing process. Besides, the supply of C5-diamine, which was reported to lead to more complex crosslinking between melanin units, to caffeic acid-based melanin synthesis was also investigated for higher production and novel functionalities. To facilitate the supply of caffeic acid and C5-diamine, E. coli strains expressing each or combinations of tyrosine ammonia lyase/p-coumarate 3-hydroxylase, feruloyl-CoA synthetase/enoyl-CoA hydratase/aldolase, and tyrosinase/lysine decarboxylase enzymes were prepared and investigated for their eumelanin, C5-diamine, and allomelanin production from L-tyrosine and L-lysine, respectively. Finally, H-NMR, FT-IR, and MALDI-TOF analysis of the synthetic melanin pigments were attempted to obtain the chemical information.


Assuntos
Proteínas de Bactérias/metabolismo , Ácidos Cafeicos/química , Escherichia coli/metabolismo , Melaninas/metabolismo , Streptomyces/metabolismo , Tirosina/química , Antioxidantes/química , Escherichia coli/crescimento & desenvolvimento , Streptomyces/crescimento & desenvolvimento
5.
Polymers (Basel) ; 11(7)2019 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-31337154

RESUMO

Cadaverine is a C5 diamine monomer used for the production of bio-based polyamide 510. Cadaverine is produced by the decarboxylation of l-lysine using a lysine decarboxylase (LDC). In this study, we developed recombinant Escherichia coli strains for the expression of LDC from Hafnia alvei. The resulting recombinant XBHaLDC strain was used as a whole cell biocatalyst for the high-level bioconversion of l-lysine into cadaverine without the supplementation of isopropyl ß-d-1-thiogalactopyranoside (IPTG) for the induction of protein expression and pyridoxal phosphate (PLP), a key cofactor for an LDC reaction. The comparison of results from enzyme characterization of E. coli and H. alvei LDC revealed that H. alvei LDC exhibited greater bioconversion ability than E. coli LDC due to higher levels of protein expression in all cellular fractions and a higher specific activity at 37 °C (1825 U/mg protein > 1003 U/mg protein). The recombinant XBHaLDC and XBEcLDC strains were constructed for the high-level production of cadaverine. Recombinant XBHaLDC produced a 1.3-fold higher titer of cadaverine (6.1 g/L) than the XBEcLDC strain (4.8 g/L) from 10 g/L of l-lysine. Furthermore, XBHaLDC, concentrated to an optical density (OD600) of 50, efficiently produced 136 g/L of cadaverine from 200 g/L of l-lysine (97% molar yield) via an IPTG- and PLP-free whole cell bioconversion reaction. Cadaverine synthesized via a whole cell biocatalyst reaction using XBHaLDC was purified to polymer grade, and purified cadaverine was successfully used for the synthesis of polyamide 510. In conclusion, an IPTG- and PLP-free whole cell bioconversion process of l-lysine into cadaverine, using recombinant XBHaLDC, was successfully utilized for the production of bio-based polyamide 510, which has physical and thermal properties similar to polyamide 510 synthesized from chemical-grade cadaverine.

6.
Sensors (Basel) ; 19(7)2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30939799

RESUMO

An accurate method for detecting vital signs obtained from a Doppler radar sensor is proposed. A Doppler radar sensor can remotely obtain vital signs such as heartbeat and respiration rate, but the vital signs obtained by using the sensor do not show clear peaks like in electrocardiography (ECG) because of the operating characteristics of the radar. The proposed peak detection algorithm extracts the vital signs from the raw data. The algorithm shows the mean accuracy of 96.78% compared to the peak count from the reference ECG sensor and a processing time approximately two times faster than the gradient-based algorithm. To verify whether heart rate variability (HRV) analysis similar to that with an ECG sensor is possible for a radar sensor when applying the proposed method, the continuous parameter variations of the HRV in the time domain are analyzed using data processed with the proposed peak detection algorithm. Experimental results with six subjects show that the proposed method can obtain the heart rate with high accuracy but cannot obtain the information for an HRV analysis because the proposed method cannot overcome the characteristics of the radar sensor itself.


Assuntos
Algoritmos , Radar , Sinais Vitais , Adulto , Eletrocardiografia , Feminino , Frequência Cardíaca , Humanos , Masculino , Taxa Respiratória , Processamento de Sinais Assistido por Computador , Telemetria , Adulto Jovem
7.
Chembiochem ; 20(12): 1498-1507, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-30676678

RESUMO

With the rapid advances in single-molecule and live-cell imaging studies to investigate biological problems, the role of chemical probes to monitor reactions in a live cell has considerably increased. However, selective labeling of a target protein or a specific residue is highly challenging due to the high complexity of the biological system. In particular, biological macromolecules (such as proteins, DNA, or RNA) share many functional groups that potentially cross-react with exogenous chemical probes. Thus, there are high demands for perfect biocompatible reactions utilizing biologically unavailable chemistry. Metal-catalyzed reactions have been extensively investigated as synthetic methodology studies, including initial attempts in applying the chemistry in aqueous solutions in vitro or even in biological conditions. Herein, the latest developments and progress in metal-catalyzed bio-orthogonal reactions for biomolecule labeling are summarized.


Assuntos
DNA/química , Proteínas/química , RNA/química , Metais/química , Coloração e Rotulagem/métodos
8.
Chembiochem ; 19(24): 2545-2549, 2018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30325101

RESUMO

Many intracellular proteins are metabolically unstable, and their half-life was known to be controlled by the "N-end rule," that is, the N-terminal residue controlled protein stability. To visualize or measure the cellular stability of a protein, depending on the N-terminal residues, attention is being paid to the development of selective labeling methods for individual N-terminal amino acids. However, there are only a limited number of functional groups available for specific N-terminal amino acid labeling in a biological environment. Herein, we report a re-examination of salicylaldehyde ester for selective N-terminal residue tagging. Salicylaldehyde ester has been used for chemical ligation to N-terminal serine or threonine under pyridine/acetic acid conditions. Inspired by previous selective serine/threonine labeling, N-terminal labeling of salicylaldehyde ester in aqueous buffer has been examined by using boron-dipyrromethene (BODIPY), rhodamine, and coumarin probes. Surprisingly, the selectivity not only significantly differed, depending on the fluorophore incorporated in salicylaldehyde, but was also perturbed by the addition of a small fraction of phosphate-buffered saline. In particular, the coumarin-based salicylaldehyde ester probe showed notable selectivity against N-terminal cysteine under aqueous buffer conditions. This result reveals the serendipitous discovery of a new N-terminal cysteine labeling strategy.


Assuntos
Aldeídos/química , Cisteína/química , Ésteres/química , Corantes Fluorescentes/química , Sondas Moleculares/química , Proteínas/química , Soluções Tampão , Cumarínicos/química , Fluorescência
9.
Angew Chem Int Ed Engl ; 57(31): 9716-9721, 2018 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-29933516

RESUMO

The current gold-standard diagnosis method for avian influenza (AI) is an embryonic egg-based hemagglutination assay followed by immunoblotting or PCR sequencing to confirm subtypes. It requires, however, specialized facilities to handle egg inoculation and incubation, and the subtyping methods relied on costly reagents. Now, the first differential sensing approach to distinguish AI subtypes is demonstrated using series of cell lines and a fluorescent sensor. Susceptibility of AI virus differs depending on genetic backgrounds of host cells. Cells were examined from different organ origins, and the infection patterns against a panel of cells were utilized for AI virus subtyping. To quantify AI infection, a highly cell-permeable fluorescent superoxide sensor was designed to visualize infection. This differential sensing strategy successfully proved discriminations of AI subtypes and demonstrated as a useful primary screening platform to monitor a large number of samples.


Assuntos
Corantes Fluorescentes/química , Vírus da Influenza A/genética , Células Madin Darby de Rim Canino/virologia , Infecções por Orthomyxoviridae/diagnóstico por imagem , Ácidos Sulfônicos/química , Superóxidos/análise , Animais , Células CHO , Linhagem Celular , Cricetulus , Cães , Humanos , Infecções por Orthomyxoviridae/genética , Superóxidos/metabolismo
10.
Enzyme Microb Technol ; 112: 59-64, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29499781

RESUMO

In this study, we engineered E. coli cells to express l-tyrosine converting enzymes, including tyrosine ammonia-lyase (TAL), p-coumarate 3-hydroxylase (C3H), feruloyl-CoA synthetase (FCS), and enoyl-CoA hydratase/aldolase (ECH). A catabolic circuit, which consisted of the protocatechualdehyde and p-hydroxybenzaldehyde production pathways, was reconstituted through combinatorial production of discrete enzymes. First, cells expressing FCS and ECH could convert each 5mM of caffeic acid and ferulic acid into protocatechualdehyde (70.5%) and vanillin (96.5%), respectively. Second, TAL and C3H were co-expressed with FCS and ECH. This strain converted l-tyrosine into caffeic acid, which was then converted into protocatechualdehyde. Ascorbic acid was used as an inhibitor of catechol aldehyde-based melanin formation, and the production yields of protocatechualdehyde and p-hydroxybenzaldehyde were 31.0±5.6 and 24.0±4.2mg/L, respectively. Finally, caffeic acid-based melanin formation was observed with higher production rate of 40.9±6.2mg/L/h by co-expressing FCS and ECH in the presence of caffeic acid.


Assuntos
Coenzima A Ligases/metabolismo , Enoil-CoA Hidratase/metabolismo , Escherichia coli/metabolismo , Melaninas/biossíntese , Tirosina/metabolismo , Amônia-Liases/genética , Amônia-Liases/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Benzaldeídos/metabolismo , Burkholderia/enzimologia , Burkholderia/genética , Coenzima A Ligases/genética , Enoil-CoA Hidratase/genética , Escherichia coli/genética , Cinética , Engenharia Metabólica , Redes e Vias Metabólicas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transcinamato 4-Mono-Oxigenase/genética , Transcinamato 4-Mono-Oxigenase/metabolismo
11.
Angew Chem Int Ed Engl ; 57(11): 2851-2854, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29377425

RESUMO

Tumor initiating cells (TICs) have been implicated in clinical relapse and metastasis of a variety of epithelial cancers, including lung cancer. While efforts toward the development of specific probes for TIC detection and targeting are ongoing, a universal TIC probe has yet to be developed. We report the first TIC-specific fluorescent chemical probe, TiY, with identification of the molecular target as vimentin, a marker for epithelial-to-mesenchymal transition (EMT). TiY selectively stains TICs over differentiated tumor cells or normal cells, and facilitates the visualization and enrichment of functionally active TICs from patient tumors. At high concentration, TiY also shows anti-TIC activity with low toxicity to non-TICs. With the unexplored target vimentin, TiY shows potential as a first universal probe for TIC detection in different cancers.


Assuntos
Corantes Fluorescentes/química , Células-Tronco Neoplásicas/patologia , Bibliotecas de Moléculas Pequenas/química , Vimentina/análise , Animais , Biomarcadores Tumorais/análise , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Transição Epitelial-Mesenquimal , Humanos , Neoplasias Pulmonares/patologia , Camundongos
12.
Angew Chem Int Ed Engl ; 57(2): 579-583, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29193627

RESUMO

Chemical probes are powerful tools for interrogating small molecule-target interactions. With additional fluorescence Turn-ON functionality, such probes might enable direct measurements of target engagement in live mammalian cells. DNS-pE (and its terminal alkyne-containing version DNS-pE2) is the first small molecule that can selectively label endogenous 3-phosphoglycerate dehydrogenase (PHGDH) from various mammalian cells. Endowed with an electrophilic vinyl sulfone moiety that possesses fluorescence-quenching properties, DNS-pE/DNS-pE2 became highly fluorescent only upon irreversible covalent modification of PHGDH. With an inhibitory property (in vitro Ki =7.4 µm) comparable to that of known PHGDH inhibitors, our probes thus offer a promising approach to simultaneously image endogenous PHGDH activities and study its target engagement in live-cell settings.


Assuntos
Corantes Fluorescentes/química , Fosfoglicerato Desidrogenase/química , Sulfonas/química , Animais , Células COS , Chlorocebus aethiops , Fluorescência , Corantes Fluorescentes/síntese química , Células Hep G2 , Humanos , Células MCF-7 , Simulação de Acoplamento Molecular , Estrutura Molecular , Espectrometria de Fluorescência
13.
Chem Commun (Camb) ; 53(100): 13332-13335, 2017 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-29188262

RESUMO

We have developed a trifunctional cleavable fluorescence turn-ON linker for chemoproteomic applications. This novel linker, which became highly fluorescent only upon cleavage of the azo bond, was successfully used for in situ proteome profiling/target identification and studies on newly synthesised proteomes.


Assuntos
Fluorescência , Proteômica , Estrutura Molecular , Proteoma/síntese química , Proteoma/química
14.
Angew Chem Int Ed Engl ; 56(39): 11816-11821, 2017 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-28783236

RESUMO

Affinity-based probes (AfBPs) provide a powerful tool for large-scale chemoproteomic studies of drug-target interactions. The development of high-quality probes capable of recapitulating genuine drug-target engagement, however, could be challenging. "Minimalist" photo-crosslinkers, which contain an alkyl diazirine group and a chemically tractable tag, could alleviate such challenges, but few are currently available. Herein, we have developed new alkyl diazirine-containing photo-crosslinkers with different bioorthogonal tags. They were subsequently used to create a suite of AfBPs based on GW841819X (a small molecule inhibitor of BRD4). Through in vitro and in situ studies under conditions that emulated native drug-target interactions, we have obtained better insights into how a tag might affect the probe's performance. Finally, SILAC-based chemoproteomic studies have led to the discovery of a novel off-target, APEX1. Further studies showed GW841819X binds to APEX1 and caused up-regulation of endogenous DNMT1 expression under normoxia conditions.


Assuntos
Reagentes de Ligações Cruzadas/química , Proteínas Nucleares/antagonistas & inibidores , Processos Fotoquímicos , Proteômica , Fatores de Transcrição/antagonistas & inibidores , Proteínas de Ciclo Celular , Humanos
15.
Asian-Australas J Anim Sci ; 28(9): 1303-8, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26194228

RESUMO

This study was conducted to investigate changes in blood enzyme parameters and to evaluate the relationship between insulin-like growth factor-1 (IGF-1), antler growth and body weight during the antler growth of sika deer (Cervus nippon). Serum enzyme activity and IGF-1 concentrations were measured in blood samples collected from the jugular and femoral veins at regular intervals during the antler growth period. Blood samples were taken in the morning from fasted stags (n = 12) which were healthy and showed no clinical signs of disease. Alfalfa was available ad libitum and concentrates were given at 1% of body weight to all stags. The experimental diet was provided at 9 am with water available at all times. There were no significant differences in alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase during antler growth, but alkaline phosphatase concentrations increased with antler growth progression, and the highest alkaline phosphatase concentration was obtained 55 days after antler casting. Serum IGF-1 concentrations measured from blood samples taken from the jugular vein during antler growth, determined that levels of IGF-1 was associated with body weight and antler growth patterns. Serum IGF-1 concentrations were higher at the antler cutting date than other sampling dates. Antler length increased significantly during antler growth (p<0.001), and there was a similar trend to between right and left beams. Body weight increased with antler growth but was not significant. Consequently it appeared that serum alkaline phosphatase concentration was related to antler growth and both antler growth and body weight were associated positively with IGF-1 concentrations during antler growth.

16.
J Agric Food Chem ; 59(6): 2584-91, 2011 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-21271724

RESUMO

This study was performed to investigate the beneficial effects of powdered whole soy milk and its hydrolysate, compared to the processed soy milk and its hydrolysate, on the alteration of lipid metabolism and their possible effects on antiobesity in C57BL/6N mice fed a high-fat and -cholesterol diet. The mice were divided into a control group (20% casein) and four test groups for 5 weeks: soy milk (SM, 20% soy milk protein), soy milk hydrolysate (SMH, 20% hydrolyzed soy milk protein), whole soy milk (WSM, 20% whole soy milk protein), and whole soy milk hydrolysate (WSMH, 20% whole soy milk hydrolysate protein). The body weight and adipose tissue weights were significantly lowered in SMH, WSM, and WSMH groups compared to the control group despite providing an isoenergetic diet. Plasma lipid concentrations and hepatic fatty acid synthase (FAS) and glucose-6-phosphate dehydrogenase (G6PD) activities were significantly lowered in all soy milk groups; however, the hepatic lipid contents and malic enzyme (ME) activity were only significantly lowered in the WSM and WSMH groups, compared to the control group. Data suggest that powdered WSM or WSMH appears to be more beneficial than SM or SMH in overall antiobesity and antihyperlipidemic properties following in the order WSMH/WSM, SMH, SM, and casein.


Assuntos
Hiperlipidemias/tratamento farmacológico , Hipolipemiantes/administração & dosagem , Obesidade/dietoterapia , Hidrolisados de Proteína/administração & dosagem , Leite de Soja/administração & dosagem , Animais , Peso Corporal , Gorduras na Dieta/efeitos adversos , Modelos Animais de Doenças , Ácido Graxo Sintases/metabolismo , Glucosefosfato Desidrogenase/metabolismo , Humanos , Hiperlipidemias/enzimologia , Hiperlipidemias/metabolismo , Hipolipemiantes/química , Lipídeos/sangue , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/enzimologia , Obesidade/metabolismo , Leite de Soja/química
17.
Bioorg Med Chem Lett ; 17(12): 3468-72, 2007 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-17420125

RESUMO

This report describes the preparation of antibacterially active emulsified polyacrylate nanoparticles in which a penicillin antibiotic is covalently conjugated onto the polymeric framework. These nanoparticles were prepared in water by emulsion polymerization of an acrylated penicillin analogue pre-dissolved in a 7:3 (w:w) mixture of butyl acrylate and styrene in the presence of sodium dodecyl sulfate (surfactant) and potassium persulfate (radical initiator). Dynamic light scattering analysis and atomic force microscopy images show that the emulsions contain nanoparticles of approximately 40 nm in diameter. The nanoparticles have equipotent in vitro antibacterial properties against methicillin-susceptible and methicillin-resistant forms of Staphylococcus aureus and indefinite stability toward beta-lactamase.


Assuntos
Resinas Acrílicas/química , Antibacterianos/farmacologia , Resistência a Meticilina , Nanopartículas/química , Penicilinas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , beta-Lactamas/farmacologia , Antibacterianos/síntese química , Portadores de Fármacos/química , Meticilina/farmacologia , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Nanopartículas/ultraestrutura , Penicilinas/administração & dosagem , Penicilinas/química , Espalhamento de Radiação , beta-Lactamas/administração & dosagem , beta-Lactamas/química
18.
Bioorg Med Chem ; 15(6): 2453-67, 2007 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-17258460

RESUMO

This study focuses on the mechanism of action of N-alkylthio beta-lactams, a new family of antibacterial compounds that show promising activity against Staphylococcus and Bacillus microbes. Previous investigations have determined that these compounds are highly selective towards these bacteria, and possess completely unprecedented structure-activity profiles for a beta-lactam antibiotic. Unlike penicillin, which inhibits cell wall crosslinking proteins and affords a broad spectrum of bacteriocidal activity, these N-thiolated lactams are bacteriostatic in their behavior and act through a different mechanistic mode. Our current findings indicate that the compounds react rapidly within the bacterial cell with coenzyme A (CoA) through in vivo transfer of the N-thio group to produce an alkyl-CoA mixed disulfide species, which then interferes with fatty acid biosynthesis. Our studies on coenzyme A disulfide reductase show that the CoA thiol-redox buffer is not perturbed by these compounds; however, the lactams appear to act as prodrugs. The experimental evidence that these beta-lactams inhibit fatty acid biosynthesis in bacteria, and the elucidation of coenzyme A as a primary cellular target, offers opportunities for the discovery of other small organic compounds that can be developed as therapeutics for MRSA and anthrax infections.


Assuntos
Antibacterianos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Compostos de Sulfidrila/química , Ácidos Tiossulfônicos/farmacologia , beta-Lactamas/farmacologia , Coenzima A/antagonistas & inibidores , Coenzima A/metabolismo , Dissulfetos/farmacologia , Testes de Sensibilidade Microbiana , Oxirredução , Relação Estrutura-Atividade
19.
Bioorg Med Chem ; 14(11): 3775-84, 2006 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-16480881

RESUMO

A study on the structure-activity profiles of N-thiolated beta-lactams 1 is reported which demonstrates the importance of the N-organothio moiety on antibacterial activity. Our results indicate that elongation of the N-alkylthio residue beyond two carbons, or extensive branching within the organothio substituent, diminishes antibacterial effects. Of the derivatives we examined, the N-sec-butylthio beta-lactam derivative 5g possesses the strongest growth inhibitory activity against methicillin-resistant Staphylococcus aureus strains. Sulfur oxidation state is important, as the N-sulfenyl and N-sulfinyl groups provide for the best antibacterial activity, while lactams bearing the N-sulfonyl or N-sulfonic acid functionalities have much weaker or no anti-MRSA properties. Stereochemistry within the organothio chain does not seem to be a significant factor, although for N-sec-butylthio beta-lactams 15a-d, the 3R,4S-lactams 15c, d are more active than the 3S,4R-stereoisomers 15a, b in agar diffusion experiments. The N-methylthio lactams are the most sensitive to the presence of glutathione, followed by N-ethylthio and N-sec-butylthio lactams, which indicates that bioactivity and perhaps bacterial selectivity of the lactams may be related to the amount of organothiols in the bacterial cell. These results support the empirical model for the mechanism of action of the compounds in which the lactam transverses the bacterial membrane to deliver the organothio moiety to its cellular target.


Assuntos
Antibacterianos/farmacologia , Resistência a Meticilina , Staphylococcus aureus/efeitos dos fármacos , Compostos de Sulfidrila/química , beta-Lactamas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Resistência a Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Modelos Biológicos , Conformação Molecular , Estereoisomerismo , Relação Estrutura-Atividade , beta-Lactamas/síntese química , beta-Lactamas/química
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