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1.
Rev Sci Instrum ; 93(9): 093517, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36182496

RESUMO

K-shell x-ray emission spectroscopy is a standard tool used to diagnose the plasma conditions created in high-energy-density physics experiments. In the simplest approach, the emissivity-weighted average temperature of the plasma can be extracted by fitting an emission spectrum to a single temperature condition. It is known, however, that a range of plasma conditions can contribute to the measured spectra due to a combination of the evolution of the sample and spatial gradients. In this work, we define a parameterized model of the temperature distribution and use Markov Chain Monte Carlo sampling of the input parameters, yielding uncertainties in the fit parameters to assess the uniqueness of the inferred temperature distribution. We present the analysis of time-integrated S and Fe x-ray spectroscopic data from the Orion laser facility and demonstrate that while fitting each spectral region to a single temperature yields two different temperatures, both spectra can be fit simultaneously with a single temperature distribution. We find that fitting both spectral regions together requires a maximum temperature of 1310-70 +90 eV with significant contributions from temperatures down to 200 eV.

2.
J Endocrinol Invest ; 44(10): 2175-2193, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33586025

RESUMO

PURPOSE: Low free testosterone (T) level in men is independently associated with presence and severity of Non-Alcoholic Steatohepatitis (NASH). The histological and molecular effects of oral testosterone prodrug LPCN 1144 treatment on hepatic fibrosis and NASH features are unknown. A metabolic syndrome-induced NASH model in rabbits consuming high fat diet (HFD) has been previously used to assess treatment effects of injectable T on hepatic fibrosis and NASH features. Here we present results on LPCN 1144 in this HFD-induced, NASH preclinical model. METHODS: Male rabbits were randomly assigned to five groups: regular diet (RD), HFD, HFD + 1144 vehicle (HFD + Veh), HFD + 1144 (1144), and HFD + 1144 + α-tocopherol (1144 + ALPHA). Rabbits were sacrificed after 12 weeks for liver histological, biochemical and genetic analyses. Histological scores were obtained through Giemsa (inflammation), Masson's trichrome (steatosis and ballooning), and Picrosirius Red (fibrosis) staining. RESULTS: Compared to RD, HFD and HFD + Veh significantly worsened NASH features and hepatic fibrosis. Considering HFD and HFD + Veh arms, histological and biomarker features were not significantly different. Both 1144 and 1144 + ALPHA arms improved mean histological scores of NASH as compared to HFD arm. Importantly, percentage of fibrosis was improved in both 1144 (p < 0.05) and 1144 + ALPHA (p = 0.05) treatment arms vs. HFD. Both treatment arms also reduced HFD-induced inflammation and fibrosis mRNA markers. Furthermore, 1144 treatments significantly improved HFD-induced metabolic dysfunctions. CONCLUSIONS: Histological and biomarker analyses demonstrate that LPCN 1144 improved HFD-induced hepatic fibrosis and NASH biochemical, biomolecular and histochemical features. These preclinical findings support a therapeutic potential of LPCN 1144 in the treatment of NASH and of hepatic fibrosis.


Assuntos
Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Fibrose/tratamento farmacológico , Inflamação/tratamento farmacológico , Síndrome Metabólica/complicações , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Testosterona/análogos & derivados , Androgênios/farmacologia , Animais , Fibrose/etiologia , Fibrose/patologia , Inflamação/etiologia , Inflamação/patologia , Masculino , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/patologia , Pró-Fármacos/farmacologia , Coelhos , Testosterona/farmacologia
3.
Sci Rep ; 11(1): 1773, 2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33469053

RESUMO

Regulation of endometrial (EM) CD8+T cells is essential for successful reproduction and protection against pathogens. Suppression of CD8+T cells is necessary for a tolerogenic environment that promotes implantation and pregnancy. However, the mechanisms regulating this process remain unclear. Sex hormones are known to control immune responses directly on immune cells and indirectly through the tissue environment. When the actions of estradiol (E2), progesterone (P) and TGFß on EM CD8+T cells were evaluated, cytotoxic activity, perforin and granzymes were directly suppressed by E2 and TGFß but not P. Moreover, incubation of polarized EM epithelial cells with P, but not E2, increased TGFß secretion. These findings suggest that E2 acts directly on CD8+T cell to suppress cytotoxic activity while P acts indirectly through induction of TGFß production. Understanding the mechanisms involved in regulating endometrial CD8+T cells is essential for optimizing reproductive success and developing protective strategies against genital infections and gynecological cancers.


Assuntos
Endométrio/citologia , Endométrio/imunologia , Estradiol/metabolismo , Progesterona/metabolismo , Linfócitos T Citotóxicos/imunologia , Fator de Crescimento Transformador beta1/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Citotoxicidade Imunológica/imunologia , Implantação do Embrião/imunologia , Implantação do Embrião/fisiologia , Feminino , Granzimas/biossíntese , Humanos , Pessoa de Meia-Idade , Perforina/biossíntese , Gravidez
4.
Artigo em Inglês | MEDLINE | ID: mdl-30670419

RESUMO

WCK 5222 is a combination of cefepime and the high-affinity PBP2-binding ß-lactam enhancer zidebactam. The cefepime-zidebactam combination is active against multidrug-resistant Gram-negative bacteria, including carbapenemase-expressing Acinetobacter baumannii The mechanism of action of the combination involves concurrent multiple penicillin binding protein inhibition, leading to the enhanced bactericidal action of cefepime. The aim of the present study was to assess the impact of the zidebactam-mediated enhanced in vitro bactericidal action in modulating the percentage of the time that the free drug concentration remains above the MIC (percent fT>MIC) for cefepime required for the in vivo killing of A. baumannii Cefepime and cefepime-zidebactam MICs were comparable and ranged from 2 to 16 mg/liter for the A. baumannii strains (n = 5) employed in the study. Time-kill studies revealed the improved killing of these strains by the cefepime-zidebactam combination compared to that by the constituents alone. Employing a neutropenic mouse lung infection model, exposure-response analyses for all the A. baumannii strains showed that the cefepime fT>MIC required for 1-log10 kill was 38.9%. In the presence of a noneffective dose of zidebactam, the cefepime fT>MIC requirement dropped significantly to 15.5%, but it still rendered a 1-log10 kill effect. Thus, zidebactam mediated the improvement in cefepime's bactericidal effect observed in time-kill studies, manifested in vivo through the lowering of cefepime's pharmacodynamic requirement. This is a first-ever study demonstrating a ß-lactam enhancer role of zidebactam that helps augment the in vivo activity of cefepime by reducing the magnitude of its pharmacodynamically relevant exposures against A. baumannii.


Assuntos
Infecções por Acinetobacter/tratamento farmacológico , Antibacterianos/farmacologia , Compostos Azabicíclicos/farmacologia , Cefepima/farmacologia , Cefalosporinas/farmacologia , Ciclo-Octanos/farmacologia , Piperidinas/farmacologia , Infecções Respiratórias/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Animais , Antibacterianos/farmacocinética , Compostos Azabicíclicos/farmacocinética , Proteínas de Bactérias/biossíntese , Cefepima/farmacocinética , Cefalosporinas/farmacocinética , Ciclo-Octanos/farmacocinética , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla , Sinergismo Farmacológico , Pulmão/microbiologia , Pulmão/patologia , Camundongos , Testes de Sensibilidade Microbiana , Piperidinas/farmacocinética , Infecções Respiratórias/microbiologia , beta-Lactamases/biossíntese
5.
Vet World ; 8(11): 1370-4, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27047045

RESUMO

AIM: Tropical theileriosis is fatal hemoprotozoal disease of dairy animals caused by Theileria annulata. The aim of the present study was to detect the T. annulata and comparison of results of molecular and microscopic techniques. MATERIALS AND METHODS: A total of 52 blood samples were collected from the cattle suspected for theileriosis across the Banaskantha district. All the samples were screened for theileriosis using Giemsa's staining technique and polymerase chain reaction (PCR). RESULTS: Total of 17 (32.69%) and 24 (46.15%) samples were found positive for theileriosis by microscopic examination and PCR test, respectively. It revealed that the study area is endemic for theileriosis, and the microscopic technique has 70.83% sensitivity and 100% specificity with respect to PCR technique. CONCLUSION: It may be concluded from the present study that the PCR is comparatively sensitive technique than microscopic examination and may be recommended to use in the field for screening of theileriosis in the study area, where a high prevalence of diseases have been reported due to intensive dairy farming.

6.
J Reprod Immunol ; 88(2): 185-94, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21353708

RESUMO

This review examines the multiple levels of pre-existing immunity in the upper and lower female reproductive tract. In addition, we highlight the need for further research of innate and adaptive immune protection of mucosal surfaces in the female reproductive tract. Innate mechanisms include the mucus lining, a tight epithelial barrier and the secretion of antimicrobial peptides and cytokines by epithelial and innate immune cells. Stimulation of the innate immune system also serves to bridge the adaptive arm resulting in the generation of pathogen-specific humoral and cell-mediated immunity. Less understood are the multiple components that act in a coordinated way to provide a network of ongoing protection. Innate and adaptive immunity in the human female reproductive tract are influenced by the stage of menstrual cycle and are directly regulated by the sex steroid hormones, progesterone and estradiol. Furthermore, the effect of hormones on immunity is mediated both directly on immune and epithelial cells and indirectly by stimulating growth factor secretion from stromal cells. The goal of this review is to focus on the diverse aspects of the innate and adaptive immune systems that contribute to a unique network of protection throughout the female reproductive tract.


Assuntos
Genitália Feminina/imunologia , Infecções/imunologia , Mucosa/imunologia , Infecções Sexualmente Transmissíveis/imunologia , Imunidade Adaptativa , Animais , Feminino , Humanos , Imunidade Inata , Infecções/transmissão , Gravidez , Infecções Sexualmente Transmissíveis/transmissão
7.
Rev Sci Instrum ; 81(10): 10D335, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21033855

RESUMO

Numerical modeling of the neutron imaging system for the National Ignition Facility (NIF), forward from calculated target neutron emission to a camera image, will guide both the reduction of data and the future development of the system. Located 28 m from target chamber center, the system can produce two images at different neutron energies by gating on neutron arrival time. The brighter image, using neutrons near 14 MeV, reflects the size and symmetry of the implosion "hot spot." A second image in scattered neutrons, 10-12 MeV, reflects the size and symmetry of colder, denser fuel, but with only ∼1%-7% of the neutrons. A misalignment of the pinhole assembly up to ±175 µm is covered by a set of 37 subapertures with different pointings. The model includes the variability of the pinhole point spread function across the field of view. Omega experiments provided absolute calibration, scintillator spatial broadening, and the level of residual light in the down-scattered image from the primary neutrons. Application of the model to light decay measurements of EJ399, BC422, BCF99-55, Xylene, DPAC-30, and Liquid A suggests that DPAC-30 and Liquid A would be preferred over the BCF99-55 scintillator chosen for the first NIF system, if they could be fabricated into detectors with sufficient resolution.

8.
J Chromatogr B Analyt Technol Biomed Life Sci ; 846(1-2): 306-12, 2007 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-17027349

RESUMO

A simple, rapid, specific, precise, accurate and sensitive method for determination of WCK 771 in human serum has been developed. The method uses high performance liquid chromatography with tandem mass spectrometric detection. Sample preparation involves protein precipitation method by addition of acetonitrile. Gatifloxacin was used as internal standard. The response was found to be linear from 0.312 to 40 microg/ml of serum with correlation coefficient greater than 0.99. Limit of detection and lower limit of quantification for WCK 771 was found to be 0.078 microg/ml and 0.312 microg/ml, respectively. The intra-day precision and accuracy from analysis of quality control (QC) samples at four concentrations was in the range of 2.36-2.58% and from 96.71 to 103.2%, respectively. The inter-day precision and accuracy from analysis of quality control samples at four concentrations was in the range of 3.14-6.82% and from 96.84 to 105.76%, respectively. WCK 771 was found to be stable for 24 h at auto-injector environment. WCK 771 was also found to be stable for 2h in serum at 25+/-3 degrees C and for 3 months at -20 degrees C. Mean absolute recovery at four different concentrations was 86.92% with standard deviation of 1.79. Throughput of the method is approximately one sample every 4 min. The method was also reproduced with monkey serum. The method was employed for estimation of drug serum levels during pre-clinical and clinical trials.


Assuntos
Fluoroquinolonas/sangue , Resistência a Meticilina , Staphylococcus aureus/efeitos dos fármacos , Espectrometria de Massas em Tandem/métodos , Animais , Fluoroquinolonas/farmacologia , Haplorrinos , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
J Chromatogr A ; 1108(1): 38-42, 2006 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-16426621

RESUMO

A sensitive, simple, specific, precise, accurate and rugged method for the assay and determination of enantiomeric purity of S-(-)-9-fluoro-6,7-dihydro-8-(4-hydroxypiperidin-1-yl)-5-methyl-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acid L-arginine salt tetrahydrate (WCK 771) in bulk drug has been developed. The method is RP-HPLC using endcapped C-18 stationary phase and chiral mobile phase. Chirality to the mobile phase was imparted with addition of beta-cyclodextrin. The UV-vis detector was operated at 290 nm. The flow rate of mobile phase was 2 ml/min. The method offers excellent separation of two enantiomers with resolution more than 2 and tailing factor less than 1.5. The method was validated for the assay of WCK 771 and quantification of R-(+)-enantiomer impurity in bulk drug. The calibration curves showed excellent linearity over the concentration range of 0.05-0.15 mg/ml for WCK 771 and 0.5-7.5 microg/ml for R-(+)-enantiomer. The precision (RSD) of the assay was 0.23%. The limit of detection and limit of quantitation of the method for WCK 771 were 0.015 and 0.06 microg/ml, respectively. The limit of detection and limit of quantitation for R-(+)-enantiomer were 0.025 and 0.09 microg/ml, respectively. The average recovery of the R-(+)-enantiomer was 100.5%. Same method was applied for the assay and determination of enantiomeric purity of WCK 771 in the intravenous formulation.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Fluoroquinolonas/análise , Cromatografia Líquida de Alta Pressão/economia , Resistência a Meticilina , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta , Staphylococcus aureus/efeitos dos fármacos , Estereoisomerismo , beta-Ciclodextrinas/química
10.
Clin Microbiol Infect ; 11(1): 9-14, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15649298

RESUMO

The activity of WCK 771, a new experimental quinolone being developed to overcome quinolone resistance in staphylococci, against quinolone-susceptible and -resistant pneumococci was determined. Comparative activities of ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, clinafloxacin, vancomycin, linezolid, amoxycillin, cefuroxime, azithromycin and clarithromycin were determined with MIC and time-kill experiments. Animal experiments were also performed to test the in-vivo anti-pneumococcal activity of WCK 771 compared to levofloxacin. WCK 771 MIC50/90 values for 300 quinolone-susceptible Streptococcus pneumoniae isolates (108 penicillin-susceptible, 92 penicillin-intermediate and 100 penicillin-resistant) were 0.5/0.5 mg/L; the MICs of beta-lactams and macrolides rose with those of penicillin G, and all isolates were susceptible to vancomycin and linezolid. WCK 771 MIC50/90 values for 25 quinolone-resistant pneumococcal isolates were 4/8 mg/L, compared to 0.5/1 mg/L for clinafloxacin, 2/4 mg/L for gatifloxacin and moxifloxacin, 8/16 mg/L for levofloxacin, and 16/>32 mg/L for ciprofloxacin. Time-kill studies showed that WCK 771 was bactericidal against pneumococci after 24 h at 4 x MIC, as were the other quinolones tested. Animal model studies showed that WCK 771 had efficacy comparable to that of levofloxacin, by both the oral and subcutaneous routes, for systemic infection caused by three quinolone-susceptible isolates of pneumococci. Overall, WCK 771 was potent both in vivo and in vitro against quinolone-susceptible, but not quinolone-resistant, S. pneumoniae, regardless of penicillin susceptibility.


Assuntos
Bacteriemia/tratamento farmacológico , Fluoroquinolonas/farmacologia , Pneumonia Pneumocócica/tratamento farmacológico , Streptococcus pneumoniae/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bacteriemia/microbiologia , Farmacorresistência Bacteriana , Fluoroquinolonas/uso terapêutico , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Pneumonia Pneumocócica/microbiologia , Resultado do Tratamento
11.
J Med Chem ; 44(6): 988-1002, 2001 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-11300880

RESUMO

A critical early event in the inflammatory cascade is the induced expression of cell adhesion molecules on the lumenal surface of vascular endothelial cells. These adhesion molecules include E-selectin, ICAM-1, and VCAM-1, which serve to recruit circulating leukocytes to the site of the inflammation. These adhesive interactions allow the leukocytes to firmly adhere to and cross the vascular endothelium and migrate to the site of tissue injury. Pharmaceutical agents which would prevent the induced expression of one or more of the cell adhesion molecules on the endothelium might be expected to provide a novel mechanism to attenuate the inflammatory responses associated with chronic inflammatory diseases. A thieno[2,3-d]pyrimidine, A-155918, was identified from a whole-cell high-throughput assay for compounds which inhibited the tumor necrosis factor-alpha (TNFalpha)-induced expression of E-selectin, ICAM-1, or VCAM-1 on human vascular endothelial cells. Traditional medicinal chemistry methods were applied to this low-micromolar inhibitor, resulting in the 2,4-disubstituted thieno[2,3-c]pyridine A-205804, a potent and selective lead inhibitor of E-selectin and ICAM-1 expression (IC(50) = 20 and 25 nM, respectively). The relative position of the nitrogen atom in the thienopyridine isomer was shown to be critical for activity, as was a small amide 2-substituent.


Assuntos
Selectina E/metabolismo , Endotélio Vascular/efeitos dos fármacos , Molécula 1 de Adesão Intercelular/metabolismo , Pirimidinas/síntese química , Administração Oral , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Depressão Química , Selectina E/genética , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Ensaio de Imunoadsorção Enzimática , Genes Reporter , Humanos , Molécula 1 de Adesão Intercelular/genética , Luciferases/genética , Regiões Promotoras Genéticas , Pirimidinas/química , Pirimidinas/farmacologia , Pirimidinas/toxicidade , Ratos , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfa/farmacologia , Veias Umbilicais/citologia , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/metabolismo
12.
J Invest Dermatol ; 117(6): 1559-65, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11886523

RESUMO

DAX-1 and SF-1 are members of the orphan nuclear receptor superfamily that are critical regulatory components of the hypothalamic-pituitary-adrenal-gonadal axis. In adrenal and gonadal tissues they regulate the expression of the cytochrome P450 steroid hydroxylase genes, key mediators of steroidogenesis. The identification of a number of steroid hydroxylases in human skin prompted us to investigate the presence of DAX-1 and SF-1. Immuno histochemical analysis of human skin revealed a distinctive staining pattern for DAX-1 and SF-1 in skin and its appendages. Prominent staining for DAX-1 was confined to the epidermis, sebaceous glands, sweat glands, and outer root sheath of the hair follicle with weaker expression in the inner root sheath, matrix cells, and dermal papilla cells. Similarly, SF-1 was also detected in the epidermis but displayed a scattered nuclear pattern across all layers. SF-1 immunoreactivity was also detected in the exocrine glands and was stronger than DAX-1 in the inner root sheath, matrix cells, and dermal papilla cells. Co-localization of DAX-1 and SF-1 was demonstrated by immunocytochemistry in the HaCaT keratinocyte cell line, primary keratinocytes, preadipocytes, and dermal papilla cells. Reverse transcriptase-polymerase chain reaction analysis demonstrated the expression of DAX-1 and SF-1 mRNA in whole human skin and Western analysis also confirmed the presence of DAX-1 protein in skin-derived cells. Our investigations demonstrate that two important regulators of steroidogeneisis are present in human skin and its appendages. These transcription factors may have a role in cutaneous steroidogenesis and thus be involved in hair follicle cycling or pathologies associated with steroids. Further studies are needed to determine the functional roles of DAX-1 and SF-1 in human skin.


Assuntos
Proteínas de Ligação a DNA/genética , Epiderme/fisiologia , Receptores do Ácido Retinoico/genética , Proteínas Repressoras , Fatores de Transcrição/genética , Células 3T3 , Animais , Western Blotting , Receptor Nuclear Órfão DAX-1 , Proteínas de Ligação a DNA/análise , Células Epidérmicas , Epiderme/química , Fatores de Transcrição Fushi Tarazu , Expressão Gênica/fisiologia , Folículo Piloso/química , Folículo Piloso/citologia , Folículo Piloso/fisiologia , Proteínas de Homeodomínio , Humanos , Imuno-Histoquímica , Queratinócitos/citologia , Queratinócitos/fisiologia , Camundongos , RNA Mensageiro/análise , Receptores Citoplasmáticos e Nucleares , Receptores do Ácido Retinoico/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator Esteroidogênico 1 , Glândulas Sudoríparas/química , Glândulas Sudoríparas/citologia , Glândulas Sudoríparas/fisiologia , Fatores de Transcrição/análise
13.
J Pharm Sci ; 88(4): 454-8, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10187757

RESUMO

Intravenous lipid emulsions are used for total parenteral nutrition and as carriers for lipophilic drugs. Exposure to the high temperature (121 degrees C) required for steam sterilization may cause coalescence and an increase in droplet size. The purpose of this study was to investigate whether an increase in the electrostatic repulsive force between oil droplets produced by formulation modification improves the thermal stability of lipid emulsions during autoclaving. The addition of a small amount, 0.66 or 1.32 mmol/kg (mm), of purified anionic phospholipid fractions (phosphatidic acid, phosphatidylglycerol, or phosphatidylinositol) to the standard formula increased the zeta potential from its normal value of -11 mV to -39 mV. Emulsions with the larger negative zeta potential did not exhibit any change in oil droplet size or distribution during steam sterilization at 121 degrees C for 15 min. The autoclaved emulsions having the larger negative zeta potential did not exhibit any evidence of coalescence when samples were stored for 1 month at 4 degrees C, room temperature, or 40 degrees C. Reduction of the negative surface charge of the oil droplets by the addition of stearylamine confirmed that the surface charge was an important factor, as emulsions having a reduced negative surface charge separated into two phases during autoclaving.


Assuntos
Emulsões/química , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Eletroquímica , Ácidos Graxos não Esterificados/química , Concentração de Íons de Hidrogênio , Fosfolipídeos/química , Esterilização , Propriedades de Superfície , Temperatura , Triglicerídeos/química
14.
J Pharm Sci ; 86(11): 1293-8, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9383743

RESUMO

A semiempirical formula was developed for the diffusion coefficient, Dp, of polymer within the diffusion layer adjacent to a matrix undergoing swelling and dissolution. This formula of Dp was a key element in a comprehensive mathematical model that described the swelling and dissolution of polymer and the release of drug. For hydroxypropyl methylcellulose (HPMC), Dp can be related to molecular weight (M) and concentration (Cp) of HPMC as Dp approximately 7.24 x 10(-5) M-0.6 [1+ 700(M/ 96000)0.7Cp/8]-2. Consistent with literature results, this formula yields Dp infinity M-0.64 under a dilute condition and Dp infinity Cp-7/4M-2 under a semidilute condition. Accordingly, the average Dp within the diffusion layer, was determined as infinity M-0.53, suggesting that the average mobility of HPMC within the diffusion layer decreases with M. This scaling law, combined with the relationship of Cp.dis infinity M-0.8, led to an important scaling law for matrix dissolution flux, Jp infinity M-1.15. The parameter Cp.dis, defined as the polymer disentanglement concentration or the polymer concentration at the tablet-diffusion layer interface, was a key parameter in that mathematical-model. The scaling law of Jp infinity M-1.15 indicates that the matrix dissolution rate decrease sharply with M at low M and gradually approaches a plateau as M becomes large. The plateau characteristics of Jp with M is consistent with the limiting drug release rate observed for HPMC-containing matrices, suggesting the critical role matrix dissolution plays in drug release.


Assuntos
Lactose/análogos & derivados , Metilcelulose/análogos & derivados , Difusão , Lactose/química , Metilcelulose/química , Oxazinas , Solubilidade
15.
J Pharm Sci ; 84(12): 1455-63, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8748329

RESUMO

Two scaling laws for predicting polymer and drug release profiles from hydrophilic matrices were developed. They were developed on the basis of the diffusion layer and the polymer disentanglement concentration, rho p,dis, the critical polymer concentration below which polymer chains detach off a gelled matrix that is undergoing simultaneous swelling and dissolution. The relation between rho p,dis and molecular weight, M1 for (hydroxypropyl)methylcellulose (HPMC) in water was established as rho p,dis (g/mL) varies M-0.8. This power-law relationship for rho p,dis, along with the diffusion layer adjacent to the gelled matrix, leads to the scaling law of mp(t)/mp(infinity) varies Meq-1.15, where mp(t)/mp(infinity) is the fractional HPMC release. The scaling law explains the observation that polymer and drug release rates decreased sharply with M at low M and approach limiting values at high M. Experimentally, mp(t)/mp(infinity) was found to scale with Meq as mp(t)/mp(infinity) varies Meq-0.93, where Meq is the equivalent matrix molecular weight. Moreover, fractional drug release, md(t)/md(infinity), followed Meq as md(t)/md(infinity) varies Meq-0.48. These two scaling laws imply that, if the release profiles are known for one composition, release profiles for other compositions can be predicted. The above two power laws lead to two master curves for mp(t)/mp(infinity) and md(t)/md(infinity), suggesting that the release mechanism for soluble drugs from HPMC matrices is independent of matrix compositions, presumably via a diffusion-controlled process. Limitations of the power laws are discussed.


Assuntos
Benzodiazepinas/química , Preparações de Ação Retardada/química , Metilcelulose/análogos & derivados , Química Farmacêutica , Derivados da Hipromelose , Metilcelulose/química , Modelos Químicos , Peso Molecular , Solubilidade , Comprimidos/química , Teofilina/química
16.
J Pharm Sci ; 84(12): 1464-77, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8748330

RESUMO

A comprehensive model is developed to describe the swelling/dissolution behaviors and drug release from hydrophilic matrices. The major thrust of this model is to employ an important physical property of the polymer, the polymer disentanglement concentration, rho p,dis, the polymer concentration below which polymer chains detach off the gelled matrix. For (hydroxypropyl)methylcellulose (HPMC) in water, we estimate that rho p,dis scales with HPMC molecular weight, M, as rho p,dis varies M-0.8. Further, matrix dissolution is considered similar to the dissolution of an object immersed in a fluid. As a result, a diffusion layer separating the matrix from the bulk solution is incorporated into the transport regime. An anisotropic expansion model is also introduced to account for the anisotropic expansion of the matrix where surface area in the radial direction dominates over the axial surface area. The model predicts that the overall tablet size and the characteristic swelling time correlate with rho p,dis qualitatively. Two scaling laws are established for fractional polymer (mp(t)/mp(infinity)) and drug (md(t)/md(infinity)) released as mp(t)/mp(infinity) varies M-1.05 and md(t)/md(infinity) varies M-0.24, consistent with the limiting polymer molecular weight effect on drug release. Model predictions for polymer and drug release agree well with observations, within 15% error. Evolution of water concentration profiles and the detailed structure of a swollen matrix are discussed.


Assuntos
Benzodiazepinas/química , Preparações de Ação Retardada/química , Metilcelulose/análogos & derivados , Química Farmacêutica , Derivados da Hipromelose , Matemática , Metilcelulose/química , Modelos Químicos , Peso Molecular
18.
J Antibiot (Tokyo) ; 47(3): 334-41, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8175486

RESUMO

A new glycopeptide antibiotic, balhimycin, has been isolated from the fermentation broth of a Amycolatopsis sp. Y-86,21022. Balhimycin belongs to the vancomycin class of glycopeptides and contains a dehydrovancosamine sugar. The biological activity of balhimycin has been compared extensively with that of vancomycin against methicillin resistant staphylococci and also against anaerobes. Balhimycin is marginally superior to vancomycin in its in vitro activity against anaerobes and in its bactericidal properties.


Assuntos
Antibacterianos , Vancomicina/análogos & derivados , Actinobacteria/classificação , Actinobacteria/metabolismo , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Proteínas Sanguíneas/metabolismo , Resistência Microbiana a Medicamentos , Fermentação , Testes de Sensibilidade Microbiana , Ligação Proteica , Staphylococcus/efeitos dos fármacos , Vancomicina/biossíntese , Vancomicina/química , Vancomicina/isolamento & purificação , Vancomicina/metabolismo , Vancomicina/farmacologia
19.
J Postgrad Med ; 37(3): 179-80, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1784035

RESUMO

A 22-year-old patient presented with a clinical picture of unilateral optic neuropathy following blunt trauma to the orbit. Clinical findings, fundus fluorescein angiography and neurophysiological studies were suggestive of an ischaemia, a rare etiology.


Assuntos
Isquemia/etiologia , Doenças do Nervo Óptico/etiologia , Nervo Óptico/irrigação sanguínea , Órbita/lesões , Ferimentos não Penetrantes/complicações , Adulto , Humanos , Masculino
20.
J Dent Res ; 66(9): 1425-30, 1987 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3040833

RESUMO

The influence of acid type (pKa effects) of weak organic acid buffers on dissolution kinetics of dental enamel was critically examined for rigorous testing of the behavioral validity of the physical model of Patel et al. (1987). Quantitative evaluation of this model indicated that monitoring initial dissolution rates was a viable approach to critical testing of the model. Initial dissolution rates were determined in 0.1 mol/L acetate (pKa = 4.77), benzoate (pKa = 4.20), and salicylate (pKa = 2.98) buffers (pH = 4.50, mu = 0.50), with ground bovine enamel blocks of known surface area mounted in a rotating disk apparatus. The Levich theory was used to study dependence of dissolution rates on stirring rates in these buffers. The experimental data were analyzed by the physical model which includes pKa effects, complexation of the buffer anion with the other ions, surface kinetics, simultaneous diffusion and equilibrium of all species in enamel pores, diffusion layer thickness, and bulk solution composition. The KIAP (formula: see text) governing the dissolution reaction and the surface resistance factor were deduced from the model. Dissolution kinetics was also followed in these buffers in the presence of calcium or phosphate common ions. In effect, by conducting both the stirring rate studies and common ion experiments, we derived the driving force function independently by these two techniques. The results obtained in this study were consistent with the model, indicating that pKa effects on the dissolution of dental enamel can be accounted for quantitatively by the model, and it was found that weak acids do not influence either the apparent solubility or the surface reaction process of bovine dental enamel.


Assuntos
Ácidos Carboxílicos/farmacologia , Cárie Dentária/metabolismo , Solubilidade do Esmalte Dentário/efeitos dos fármacos , Acetatos/farmacologia , Animais , Benzoatos/farmacologia , Cálcio/análise , Bovinos , Fenômenos Químicos , Físico-Química , Esmalte Dentário/análise , Durapatita , Hidroxiapatitas/análise , Cinética , Matemática , Fosfatos/análise , Salicilatos/farmacologia
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