A mechanism for matrikine regulation in acute inflammatory lung injury.

Proline-glycine-proline (PGP) and its acetylated form (Ac-PGP) are neutrophil chemoattractants generated by collagen degradation, and they have been shown to play a role in chronic inflammatory disease. However, the mechanism for matrikine regulation in acute inflammation has not been well established. Here, we show that these peptides are actively transported from the lung by the oligopeptide transporter, PEPT2. Following intratracheal instillation of Ac-PGP in a mouse model, there was a rapid decline in concentration of the labeled peptide in the bronchoalveolar lavage (BAL) over time and redistribution to extrapulmonary sites. In vitro knockdown of the PEPT2 transporter in airway epithelia or use of a competitive inhibitor of PEPT2, cefadroxil, significantly reduced uptake of Ac-PGP. Animals that received intratracheal Ac-PGP plus cefadroxil had higher levels of Ac-PGP in BAL and lung tissue. Utilizing an acute LPS-induced lung injury model, we demonstrate that PEPT2 blockade enhanced pulmonary Ac-PGP levels and lung inflammation. We further validated this effect using clinical samples from patients with acute lung injury in coculture with airway epithelia. This is the first study to our knowledge to determine the in vitro and in vivo significance of active matrikine transport as a mechanism of modulating acute inflammation and to demonstrate that it may serve as a potential therapeutic target.

Reanalysis of cefazolin surrogate susceptibility breakpoints utilized as guidances for oral cephalosporin treatments of uncomplicated urinary tract infections: caution concerning application to cefadroxil.

Based on antimicrobial susceptibility test interpretive breakpoint criteria from Clinical and Laboratory Standards Institute and United States Committee on Antimicrobial Susceptibility Testing, cefazolin uncomplicated urinary tract infection (uUTI) surrogate breakpoints do not accurately predict cefadroxil or cephradine susceptibility when testing indicated Enterobacteriaceae species isolates. Hence, these two orally-administered cephalosporins (OC) are not equivalent spectrum substitutes for cephalexin or six other related OC agents for contemporary uUTI therapy.

Fabrication, physical characterizations and in vitro antibacterial activity of cefadroxil-loaded chitosan/poly(vinyl alcohol) nanofibers against Staphylococcus aureus clinical isolates.

Particular attention is devoting to the design of electrospun nanofibers (NFs) as new drug delivery nanosystems to overcome bacterial resistance and toxicological issues. Their advantages include high encapsulation efficiency, great drug-loading capacity, easiness in production, cost-effectiveness, and controlled targeted drug delivery. We aim to characterize electrospun chitosan (CS)/poly(vinyl alcohol) (PVA) NFs (CPNFs) loaded with cefadroxil monohydrate (CFX), a broad spectrum antibiotic. The biodegradable and biocompatible carrier system was greenly fabricated by electrospinning at various CS/PVA ratios. CPNFs were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and UV-spectrometry. Their potential toxicity was evaluated in human epidermal keratinocytes by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Their antibacterial activity was tested by agar well diffusion method and MTT assay against clinical isolates of Staphylococcus aureus, a Gram-positive bacterium involved in serious skin infections. The thermostable CFX-loaded CPNFs at optimized 30:70 ratio revealed a burst and sustained release profile that occurred predominantly by diffusion following non-Fickian (anomalous) transport mechanism, as well as a more potent and safe antibacterial than free CFX. Thus, electrospun CFX-loaded CPNFs could be a new promising transdermal drug delivery system to activate the wound healing process and cost-effectively treat S. aureus-induced (resistant) skin infections.

[Susceptibility to first-generation Cephalosporins in Enterobacteriaceae isolated from urine culture according to CLSI and EUCAST breakpoints]. / Estudio de susceptibilidad a cefalosporinas de primera generación en enterobacterias aisladas de urocultivo, según criterios CLSI y EUCAST.

Currently, the use of cefazolin is recommended to determine the susceptibility to first-generation oral cephalosporins in strains of enterobacteria in uncomplicated UTI. We determined susceptibility differences to oral cephalosporins in urinary strains according to cefazolin or cefalotin breakpoints and the correlation of susceptibility between cefazolin and cefadroxil. We studied 52 strains with cefalotin and cefazolin by disk-diffusion and MIC (Kirby-Bauer and Vitek XL) and a subgroup by disk-diffusion for cefadroxil. Agreement among different methods was 100% for K. pneumoniae and Proteus spp. In Escherichia coli, agreement for Vitek and disk-diffusion were 0 and 50% respectively. Susceptibility to first generation cephalosporins in E. coli should be determined with cefazolin. Agreement between cefazolin and cefadroxil suggests that cefazolin could also predict the susceptibility of cefadroxil.

Estudio de susceptibilidad a cefalosporinas de primera generación en enterobacterias aisladas de urocultivo, según criterios CLSI y EUCAST / Susceptibility to first-generation Cephalosporins in Enterobacteriaceae isolated from urine culture according to CLSI and EUCAST breakpoints

Resumen Actualmente se recomienda el uso de cefazolina para determinar la susceptibilidad a cefalosporinas orales de primera generación en cepas de enterobacterias en ITU no complicada. Nuestro objetivo fue establecer la susceptibilidad a cefalosporinas orales en cepas urinarias según puntos de corte para cefalotina o cefazolina y la correlación de susceptibilidad entre cefazolina y cefadroxilo. Se estudió la concordancia entre cefalotina y cefazolina en 52 cepas por método de Kirby-Bauer y Vitek XL. En Escherichia coli fue de 0% para VitekXL y 50% para Kirby-Bauer. La concordancia entre cefazolina y cefadroxilo fue 95,6%. En el laboratorio debiera usarse cefazolina para determinar susceptibilidad a cefalosporinas orales de primera generación. La concordancia entre cefazolina y cefadroxilo sugiere que cefazolina podría predecir susceptibilidad para cefadroxilo.

Currently, the use of cefazolin is recommended to determine the susceptibility to first-generation oral cephalosporins in strains of enterobacteria in uncomplicated UTI. We determined susceptibility differences to oral cephalosporins in urinary strains according to cefazolin or cefalotin breakpoints and the correlation of susceptibility between cefazolin and cefadroxil. We studied 52 strains with cefalotin and cefazolin by disk-diffusion and MIC (Kirby-Bauer and Vitek XL) and a subgroup by disk-diffusion for cefadroxil. Agreement among different methods was 100% for K. pneumoniae and Proteus spp. In Escherichia coli, agreement for Vitek and disk-diffusion were 0 and 50% respectively. Susceptibility to first generation cephalosporins in E. coli should be determined with cefazolin. Agreement between cefazolin and cefadroxil suggests that cefazolin could also predict the susceptibility of cefadroxil.

Reconstrução mamária imediata com retalho do músculo grande dorsal e implante de silicone / Immediate breast reconstruction with latissimus dorsi flap and silicone implant

Introdução: O primeiro tratamento eficaz para o câncer de mama foi descrito em 1894. A partir das décadas de 60 e 70, cirurgias menos agressivas foram desenvolvidas, sem prejuízos oncológicos. Com evolução histórica semelhante, o retalho do músculo grande dorsal (RMGD) foi introduzido em 1906. Contudo, apenas 70 anos após sua primeira descrição, ele ganhou popularidade como uma opção para as reconstruções mamárias. Método: Estudo clínico retrospectivo realizado por meio da coleta de dados de 22 pacientes submetidas à reconstrução mamária imediata com emprego do RMGD associado a implante de silicone durante o período de fevereiro de 2012 a dezembro de 2013. Resultados: Não houve necrose do retalho de grande dorsal ou perda da reconstrução mamária nos casos estudados. Foram observados 10 casos (45%) de seroma em região dorsal, 3 casos (14%) de necrose parcial da pele da mastectomia e 3 casos (14%) de deiscência parcial da ferida operatória. Não foram evidenciados fatores de risco com significância estatística para as complicações apresentadas. Ocorreram 4 casos (18,18%) de alterações de cobertura do implante, com atrofia muscular e cutânea, e 2 casos (9,09%) de contratura capsular. Apenas um caso não foi associado à radioterapia. Contudo, não houve significância estatística em relação à radioterapia adjuvante e às complicações tardias apresentadas (p = 0,635). Conclusão: O RMGD associado ao implante de silicone é uma opção segura e confiável para a reconstrução mamária imediata após mastectomias.

Introduction: The first effective breast cancer treatment was described in 1894. Less aggressive surgeries were developed in the 1960s and 70s, without increased mortality due to cancer. With similar historical evolution, the latissimus dorsi muscle flap (LDMF) procedure was introduced in 1906. Seventy years after its first description, LDMF gained popularity as an option for breast reconstruction. Method: A retrospective clinical study was conducted using data obtained from 22 patients undergoing immediate breast reconstruction with LDMF and silicone implants between February 2012 and December 2013. Results: No latissimus dorsi flap necrosis or breast reconstruction losses were observed in this study. Ten cases (45%) of seroma were detected in the dorsal region, three cases (14%) of partial necrosis of the mastectomized skin, and three cases (14%) of partial surgical wound dehiscence. Statistical significant risk factors for the complications observed have not been emphasized. There were four cases (18.18%) of muscle and skin atrophy associated with implants, and two cases (9.09%) of capsular contracture. Only one case was not associated with radiotherapy. However, there were no statistically significant differences in adjuvant radiotherapy and late complications (p = 0.635). Conclusion: LDMF associated with silicone implants is a safe and reliable option for immediate breast reconstruction after mastectomies.

Expression and function of PEPT2 during transdifferentiation of alveolar epithelial cells.

AIMS: The purpose of this study was to clarify the expression and function of peptide transporter 2 (PEPT2) in primary cultured alveolar type II epithelial cells and in transdifferentiated type I-like cells. MAIN METHODS: Real-time PCR analysis, uptake study of [(3)H]Gly-Sar, and immunostaining were performed in alveolar epithelial cells. KEY FINDINGS: The expression of PEPT2 mRNA in type II cells isolated from rat lungs was highest at day 0, and decreased rapidly during culture of the cells. In accordance with this change, PEPT2 activity estimated as cefadroxil-sensitive [(3)H]Gly-Sar uptake also decreased along with transdifferentiation. The expression of PEPT2 protein in type II cells was confirmed by immunostaining and Western blot analysis. The uptake of [(3)H]Gly-Sar in type II cells was time- and pH-dependent. In contrast, minimal time-dependence and no pH-dependence of [(3)H]Gly-Sar uptake were observed in type I-like cells. The maximal [(3)H]Gly-Sar uptake was observed at pH6.0, and the uptake decreased at higher pHs in type II cells. The uptake of [(3)H]Gly-Sar in type II cells was inhibited by cefadroxil in a concentration-dependent manner, the IC50 value being 4.3 µM. On the other hand, no significant inhibition by cefadroxil was observed in type I-like cells. In addition, [(3)H]Gly-Sar uptake in type II cells was saturable, the Km value being 72.0 µM. SIGNIFICANCE: PEPT2 is functionally expressed in alveolar type II epithelial cells, but the expression decreases along with transdifferentiation, and PEPT2 would be almost completely lost in type I cells.

Kyotorphin transport and metabolism in rat and mouse neonatal astrocytes.

Neuropeptide inactivation is generally thought to occur via peptidase-mediated degradation. However, a recent study found increased analgesia after L-kyotorphin (L-Tyr-L-Arg; L-KTP) administration in mice lacking an oligopeptide transporter, PEPT2. The current study examines the role of PEPT2 in L-KTP uptake by astrocytes and compares it to astrocytic L-KTP degradation. L-[(3)H]KTP uptake was measured in primary cultures of neonatal astrocytes from rats and from Pept2(+/+) and Pept2(-/-) mice. Uptake was further characterized using potential inhibitors. L-[(3)H]KTP degradation was examined in primary astrocyte cultures from Pept2(-/-) mice by following the formation of L-[(3)H]tyrosine. The uptake of L-[(3)H]KTP in both rat and Pept2(+/+) mouse neonatal astrocytes was inhibited by known PEPT2 inhibitors. L-[(3)H]KTP uptake was also reduced in Pept2(-/-) astrocytes as compared to those from Pept2(+/+) mice. Kinetic analysis indicated the presence of a high affinity (K(m) approximately 50 microM) transporter for L-[(3)H]KTP, identified as Pept2, and a low affinity transporter (K(m) approximately 3-4 mM), inhibited by amastatin, bestatin and tyrosine. Astrocytes also degraded L-KTP through a low affinity peptidase (K(m) approximately 2 mM). Astrocytic clearance of L-KTP occurs via both peptidase activity and transport. These processes occur at similar rates and may be linked. This supports the contention that oligopeptide transport may have an impact on the extracellular clearance (and potentially activity) of certain neuropeptides.

In vitro activity of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements.

Evidences supporting the introduction of metallic elements in several biological processes are rapidly accumulating. Likewise, many drugs possess modified toxicological and pharmacological properties when in the form of metal complexes. In order to ascertain the role of various essential and trace element complexation on the antibacterial activity of various cephalosporins, the synergistic or antagonistic behavior of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements has been studied and compared with the parent drug. The essential and trace elements comprised of magnesium, calcium, chromium, manganese, ferric, cobalt, nickel, copper, zinc and cadmium in the form of their chloride. These studies were carried out by observing the minimum inhibitory concentration (MIC) using agar dilution method and compared with the MIC'S of the standard cephalosporins against various species of Gram (+) and Gram (-) microorganisms such as Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi and Shigella dysenteriae. Different dilutions of cephalosporins and salts of essential and trace elements were used in these studies. The ratio of the drug and metal salts was 1:1 and the reactions were carried out at two different temperatures as 37 degrees C and 60 degrees C in order to study the complex formation. The aim of our study was on one hand to evaluate the changes in microbiological activity of the standard cephalosporins after in vitro metal interactions to study the synergetic or antagonistic behavior of the later through the difference in MICs values of these cephalosporins and on the other hand to access the bioassay directed extent of drug metal complexations. Our investigation reveal that interaction of above cephalosporins with essential and trace elements cause antagonistic effect in many cases which was shown by decrease in antimicrobial activity of cephalosporins and MIC values were increased.

Extracción de amblyomma cajennense (fabricius, 1787) de un caso de otoacariasis humana en el Estado Sucre-Venezuela / Extraction of amblyomma cajennense (fabricius, 1787) a case of human otoacariasis in the State Sucre-Venezuela

El ingreso accidental de insectos y otros artrópodos en el canal auditivo es una etiología común de los cuerpos extraños en otorrinolaringología. La infestación humana con especies del genero Amblyomma es infrecuentemente reportada. Se reporta el caso de un paciente masculino de 7 años de edad, natural y procedente de Tunapuy, Municipio Libertador, Estado Sucre, cuya madre refiere la introducción de un "insecto" en el oído derecho en horas de la madrugada. El paciente presentó dolor de moderada a fuerte intensidad en el oído derecho. Al evaluarse el canal auditivo por otoscopia se evidenció la presencia de una garrapata de <5 mm de largo, la cual fue extraída con pinzas, posterior a la colocación directa de xilocaína al 2 por ciento en el canal auditivo. No se observaron signos de lesión significativa, inflamación o supuración. Se le indicó profilaxis antimicrobiana con cefadroxilo 30 mg/Kg/d bid vo, así como nimesulide 5 mg/kg/d bid vo, ambos por 5 días. El paciente fue reevaluado a los 14 días, no presentando sintomatología alguna, ni signos de enfermedad local o sistémica. Posteriormente la garrapata aislada del oído fue identificada taxonómicamente según las claves de Hoogstraal y Jones, como Amblyomma cajennense. Esta garrapata se ha descrito aislada de diversos hospedadores mamíferos, incluyendo al humano; reportándose en los Estados Amazonas, Anzoátegui, Apure, Bolívar, Carabobo, Falcón, Guárico, Lara, Miranda, Yaracuy y Zulia. De acuerdo a la revisión realizada, éste es el primer reporte de su descripción en el Estado Sucre.

Linezolid for the treatment of methicillin-resistant Staphylococcus aureus infections in children.

BACKGROUND: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are becoming increasingly prevalent. Linezolid is effective and well-tolerated in the treatment of adults with MRSA infections. OBJECTIVE: To evaluate the clinical efficacy and safety of iv/oral linezolid in children with MRSA infections. METHODS: Data were obtained from two independent clinical trials. In an outpatient trial children (5 to 17 years of age) with uncomplicated skin and skin structure infections (SSSIs) were treated with linezolid or cefadroxil. In an inpatient trial hospitalized children (0 to 11 years of age) with pneumonia, bacteremia or complicated SSSI caused by resistant Gram-positive pathogens were administered iv linezolid with the option to switch to oral suspension (patients >90 days of age) or iv vancomycin. A subset of patients with MRSA infections from the two clinical trials is analyzed herein. RESULTS: In the outpatient trial children with skin infections caused by MRSA were treated with linezolid (15 patients) and cefadroxil (10 patients). In the microbiologically evaluable population, the clinical cure rate was 92.3% in the linezolid group and 85.7% in the cefadroxil group (P = 0.64). The pathogen eradication rate for MRSA was 92.3 and 85.7% in the linezolid and cefadroxil groups, respectively (P = 0.64). There were very few adverse events or drug-related adverse events and no serious adverse events in the outpatient trial. In the inpatient trial 20 children treated with linezolid and 14 treated with vancomycin had infections caused by MRSA. In the microbiologically evaluable population, the clinical cure rate was 94.1% in the linezolid group and 90.0% in the vancomycin group (P = 0.69). Pathogen eradication rates were 88.2 and 90.0% for the linezolid and vancomycin groups, respectively (P = 0.89). Susceptibility patterns of the MRSA isolates showed distinct patterns between the outpatient and inpatient trials. In the inpatient trial fewer patients in the linezolid group had drug-related adverse events than did those in the vancomycin group (20% vs. 43%; P = 0.15). CONCLUSIONS: Intravenous/oral linezolid is effective and well-tolerated in children with MRSA infections.

Safety and tolerability of linezolid in children.

BACKGROUND: Linezolid, an oxazolidinone, is effective in the treatment of adults and children with community-acquired and nosocomial pneumonia and uncomplicated and complicated skin and skin structure infections (SSSIs), including infections caused by Gram-positive resistant pathogens. Because of the increasing use of linezolid, it is important to review the common adverse events (AEs) associated with its use in children with the use of data from clinical trials. OBJECTIVE: The safety and tolerability of linezolid in pediatric patients with Gram-positive infections were determined in four pediatric clinical studies. Study I included pediatric patients with community-acquired pneumonia; Study II included otitis media; Study III included SSSIs; and Study IV included complicated SSSIs, nosocomial pneumonia and bacteremia. METHODS: Studies I and II had no comparator arm. Study III was randomized and compared linezolid with cefadroxil. Study IV also was randomized and compared linezolid with vancomycin. Patients <12 years of age received linezolid 10 mg/kg; patients age 12 years and older received 600 mg (intravenous/oral). Dosing frequency (two to three times daily) varied depending on age and clinical diagnosis. The primary safety endpoints were AEs, drug-related AEs, serious AEs and selected laboratory tests. RESULTS: In the 4 studies 958 patients were included in the intent-to-treat analysis. In the linezolid vs. cefadroxil study (Study III), the most common AEs in patients treated with linezolid were diarrhea (7.8%), headache (6.5%) and upper respiratory tract infection (3.7%). In the linezolid vs. vancomycin study (Study IV), the most common AEs in the linezolid group were fever (14.1%), diarrhea (10.8%) and vomiting (9.4%). The most common drug-related AEs for linezolid in all 4 studies were diarrhea, vomiting, loose stools and nausea. None of these common AEs or drug-related AEs occurred more frequently in patients treated with linezolid than in those in the comparator group. CONCLUSIONS: Linezolid was safe and well-tolerated in pediatric patients with community-acquired pneumonia, otitis media, SSSIs and infections caused by Gram-positive resistant pathogens.

In-vitro and in-vivo antibacterial activity evaluation of a polyurethane matrix.

Various in-vitro and in-vivo methods for evaluation of the duration of antibacterial activity were compared using a controlled-release polyurethane matrix developed for the prevention of surface bacterial adhesion and growth. Cefadroxil was incorporated into this polyurethane matrix by a solvent casting method before the matrix was coated with polyurethane in tetrahydrofuran solution. The release of cefadroxil from the matrix into distilled water at 37 degrees C was measured by HPLC. The morphological change of matrices before and after release studies was investigated by scanning electron microscopy (SEM). The duration of antimicrobial activity of the matrix against Escherichia coli and Staphylococcus aureus was evaluated by measuring the diameters of the inhibition zone and the optical density of the broth. The matrices were also implanted subcutaneously in rats and the duration of the antibacterial activity was determined by measuring the inhibition zone. The results showed that duration of antibacterial activity of the polyurethane matrix was successfully determined in-vitro by these methods, and the results differed from the conventional in-vitro release study. It was also possible to determine the duration of action of the matrix in-vivo by implanting the matrix in rats, and then measuring the antibacterial activity of the matrix at predetermined time intervals. While a good correlation was observed between the in-vitro and in-vivo methods used in this study to evaluate the duration of the antibacterial activity of the polymeric matrix, the conventional in-vitro release study did not coincide with these results.

Interaction of human and rat organic anion transporter 2 with various cephalosporin antibiotics.

Cephalosporin antibiotics are thought to be excreted into the urine via organic anion transporters (OATs) and OAT can mediate nephrotoxicity by cephalosporins, particularly by cephaloridine. The purpose of this study was to elucidate the interaction of human-OAT2 and rat-OAT2 with cephalosporin antibiotics using proximal tubule cells stably expressing human-OAT2 and rat-OAT2. Human-OAT2 is localized to the basolateral side of the proximal tubule, whereas rat-OAT2 is localized to the apical side of the proximal tubule. Cephalosporins tested were cephalothin, cefoperazone, cefazolin, ceftriaxone, cephaloridine, cefotaxime, cefadroxil and cefamandole. These cephalosporins dose-dependently inhibited organic anion uptake mediated by human-OAT2 and rat-OAT2. There was no species difference observed for the effects of OAT2 with cephalosporins between human and rat transporters. Kinetic analysis revealed that the inhibitory effects for human-OAT2 were competitive. Cephaloridine significantly decreased the viability of cells stably expressing human-OAT2, human-OAT1, human-OAT3 and human-OAT4. The decreased viability of cells stably expressing human-OAT1, human-OAT3 and human-OAT4 but not human-OAT2 was reversed by probenecid. In conclusion, human-OAT2 interacts with cephalosporins, and thus, human-OAT2 may mediate the uptake of cephalosporins on the basolateral side of the proximal tubule. The interaction of human-OAT2 with cephalosporins was the weakest among the basolateral human-OATs tested. In addition, it is suggested that human-OATs mediate cephaloridine-induced nephrotoxicity.

Interaction of human organic anion transporters with various cephalosporin antibiotics.

Cephalosporin antibiotics are thought to be excreted into the urine via organic anion transporters (OATs). The purpose of this study was to elucidate the interaction of human-OATs with various cephalosporin antibiotics, using proximal tubule cells stably expressing human-OAT1, human-OAT3 and human-OAT4. Human-OAT1 and human-OAT3 are localized to the basolateral side of the proximal tubule, whereas human-OAT4 is localized to the apical side. The cephalosporin antibiotics tested were cephalothin, cefoperazone, cefazolin, ceftriaxone, cephaloridine, cefotaxime, cefadroxil and cefamandole. All of these cephalosporin antibiotics significantly inhibited organic anion uptake mediated by human-OAT1, human-OAT3 and human-OAT4. Kinetic analysis revealed that these inhibitions were competitive. The inhibition constant (K(i)) values of cefoperazone, cefazolin, ceftriaxone and cephaloridine for human-OAT1 were much lower than those for human-OAT3 and human-OAT4, whereas the K(i) values of cephalothin and cefotaxime for human-OAT3 were much lower than those for human-OAT1 and human-OAT4. Human-OAT4 mediated the bidirectional transport of estrone sulfate, an optimal substrate for human-OAT4. These results suggest that human-OAT1, human-OAT3 and human-OAT4 interact with various cephalosporin antibiotics, and that human-OAT1 and human-OAT3 play a distinct role in the basolateral uptake of cephalosporin antibiotics. Since the K(i) value of cephaloridine for human-OAT4-mediated organic uptake was much higher than that for human-OAT1, the results indicate the possibility that human-OAT4 limits the efflux of cephaloridine, leading to the accumulation of cephaloridine and the induction of nephrotoxicity.

Distribution and function of the peptide transporter PEPT2 in normal and cystic fibrosis human lung.

BACKGROUND: Aerosol administration of peptide based drugs has an important role in the treatment of various pulmonary and systemic diseases. The characterisation of pulmonary peptide transport pathways can lead to new strategies in aerosol drug treatment. METHODS: Immunohistochemistry and ex vivo uptake studies were established to assess the distribution and activity of the beta-lactam transporting high affinity proton coupled peptide transporter PEPT2 in normal and cystic fibrosis human airway tissue. RESULTS: PEPT2 immunoreactivity in normal human airways was localised to cells of the tracheal and bronchial epithelium and the endothelium of small vessels. In peripheral lung immunoreactivity was restricted to type II pneumocytes. In sections of cystic fibrosis lung a similar pattern of distribution was obtained with signals localised to endothelial cells, airway epithelium, and type II pneumocytes. Functional ex vivo uptake studies with fresh lung specimens led to an uptake of the fluorophore conjugated dipeptide derivative D-Ala-L-Lys-AMCA into bronchial epithelial cells and type II pneumocytes. This uptake was competitively inhibited by dipeptides and cephalosporins but not ACE inhibitors, indicating a substrate specificity as described for PEPT2. CONCLUSIONS: These findings provide evidence for the expression and function of the peptide transporter PEPT2 in the normal and cystic fibrosis human respiratory tract and suggest that PEPT2 is likely to play a role in the transport of pulmonary peptides and peptidomimetics.

No evidence for active peptide transport in forestomach epithelia of sheep.

The transport of peptides was studied with isolated preparations of rumen and omasum tissue of sheep by using the conventional Ussing-chamber method and isolated ruminal cells (REC). Mucosal addition of glycyl-L-glutamine, captopril (angiotensin converting enzyme inhibitor) or cefadroxil (beta-lactam antibiotic) did not change the short-circuit current (I(sc)), or tissue conductance (G(t)). The intracellular pH, pH(i), in isolated REC was not influenced by the addition of peptides to the buffer solution. These findings do not support the assumption of proton-coupled or electrogenic peptide transport. The determination of unidirectional flux rates of the peptide D-phenylalanyl-L-alanine (2,3-(3)H) showed that the flux rate in the serosal-mucosal direction, J(sm), was greater than J(ms), leading to a small net secretion of peptide. Transport was not significantly inhibited by the serosal addition of ouabain. Enhancing the paracelluIar permeability by an increase of osmotic pressure in the mucosal solution (FREYER and MARTENS, Proc. Soc. Nutr. Physiol. 8, 80, 1999) caused an increase of G(t) and significantly higher transport rates of peptide. The flux rates of peptides (in the nanomolar range) may therefore represent passive and possibly paracellular diffusion and are not of nutritional importance.

The effect of pore formers on the controlled release of cefadroxil from a polyurethane matrix.

The effect of various pore formers on the controlled release of an antibacterial agent from a polymeric device was examined in order to develop a novel biomaterial that prevents bacterial adhesion and growth on its surface. Cefadroxil was chosen as the model antibiotic and was incorporated into a polyurethane matrix by the solvent-casting method. Polyethylene glycol (PEG) 1450, D-mannitol, or bovine serum albumin (BSA) was used as a pore former. The amount of cefadroxil released from various formulations at 37 degrees C was measured by HPLC. The morphological change of matrices before and after release studies was investigated by scanning electron microscopy (SEM). The duration of antimicrobial activities of matrices against Escherichia coli and Bacillus subtilis was evaluated by measuring the diameters of the inhibition zone. Changing the weight fraction and particle size of the pore formers/drug mixtures could control the release of cefadroxil from the matrix. The release rate of cefadroxil increased as the loading dose of the pore former increased (15<20<25%). Cefadroxil released from these devices exhibited antibacterial activity for 5-6 days. These results imply that an antibiotic-loaded polymeric device that could prevent bacterial infection on its surface can be formulated using appropriate pore formers.