Chronopharmacological study of cephalexin in dogs

Recent studies have identified a 24 h rhythm in the expression and function of PEPT1 in rats, with significantly higher levels during the nighttime than daytime. Similarly, temporal variations have been described in glomerular filtration rate and renal blood flow, both being maximal during the activity phase and minimal during the rest phase in laboratory rodents. The aim of this study was to assess the hypothesis that the absorption of the first-generation cephalosporin antibiotic cephalexin by dogs would be less and the elimination would be slower after evening (rest span) compared to morning (activity span) administration, and whether such administration-time changes could impair the medication's predicted clinical efficacy. Six (3 male, 3 female; age 4.83+/-3.12 years) healthy beagle dogs were studied. Each dog received a single dose of 25 mg/kg of cephalexin monohydrate per os at 10:00 and 22:00 h, with a two-week interval of time between the two clock-time experiments. Plasma cephalexin concentrations were determined by microbiological assay. Cephalexin peak plasma concentration was significantly reduced to almost 77% of its value after the evening compared to morning (14.52+/-2.7 vs. 18.77+/-2.8 microg/mL) administration. The elimination half-life was prolonged 1.5-fold after the 22:00 h compared to the 10:00 h administration (2.69+/-0.9 vs. 1.79+/-0.2 h). The area under the curve and time to reach peak plasma concentration did not show significant administration-time differences. The duration of time that cephalexin concentrations remained above the minimal inhibitory concentrations (MIC) for staphylococci susceptiblity (MIC=0.5 microg/mL) was>70% of each of the 12 h dosing intervals (i.e., 10:00 and 22:00 h). It can be concluded that cephalexin pharmacokinetics vary with time of day administration. The findings of this acute single-dose study require confirmation by future steady-state, multiple-dose studies. If such studies are confirmatory, no administration-time dose adjustment is required to ensure drug efficacy in dogs receiving an oral suspension of cephalexin in a dosage of 25 mg/kg at 12 h intervals.     

Noninvasive Visualization of the Activated αvβ3 Integrin in Cancer Patients by Positron Emission Tomography and [18F]Galacto-RGD

BackgroundThe integrin αvβ3 plays an important role in angiogenesis and tumor cell metastasis, and is currently being evaluated as a target for new therapeutic approaches. Several techniques are being studied to enable noninvasive determination of αvβ3 expression. We developed [¹⁸F]Galacto-RGD, a ¹⁸F-labeled glycosylated αvβ3 antagonist, allowing monitoring of αvβ3 expression with positron emission tomography (PET).ConclusionsMolecular imaging with [¹⁸F]Galacto-RGD and PET can provide important information for planning and monitoring anti-angiogenic therapies targeting the αvβ3 integrins and can reveal the involvement and role of this integrin in metastatic and angiogenic processes in various diseases.     

Depleted genetic variation of the European ground squirrel in Central Europe in both microsatellites and the major histocompatibility complex gene: implications for conservation

Habitat fragmentation may influence the genetic make-up and adaptability of endangered populations. To facilitate genetic monitoring of the endangered European ground squirrel (EGS), we analyzed 382 individuals from 16 populations in Central Europe, covering almost half of its natural range. We tested how fragmentation affects the genetic architecture of presumably selectively neutral (12 microsatellites) and non-neutral (the major histocompatibility class II DRB gene) loci. Spatial genetic analyses defined two groups of populations, “western” and “eastern”, with a significantly higher level of habitat fragmentation in the former group. The highly fragmented western populations had significantly lower genetic diversity in both types of markers. Only one allele of the DRB gene predominated in populations of the western group, while four alleles were evenly distributed across the eastern populations. Coefficient of inbreeding values (F _IS) calculated from microsatellites were significantly higher in the western (0.27–0.79) than in eastern populations (−0.060–0.119). Inter-population differentiation was very high, but similar in both groups (western F _ST = 0.23, eastern F _ST = 0.25). The test of isolation by distance was significant for the whole dataset, as well as for the two groups analyzed separately. Comparison of genetic variability and structure on microsatellites and the DRB gene does not provide any evidence for contemporary selection on MHC genes. We suggest that genetic drift in small bottlenecked and fragmented populations may overact the role of balancing selection. Based on the resulting risk of inbreeding depression in the western populations, we support population management by crossbreeding between the western and eastern populations.     

Chromosomal insertion of human papillomavirus 18 sequences in HeLa cells detected by nonisotopic in situ hybridization and reflection contrast microscopy

Summary Genomic insertion of human papillomavirus (HPV) sequences is associated with the genesis of cervical carcinoma, and HPV-induced incipient cellular alterations may also present a requisite for the establishment of cell lines such as HeLa. Considering the theoretical importance of specific viral integration sites, we attempted to detect in HeLa cells the chromosomal location of DNA sequences homologous to HPV-16 and HPV-18 sequences by a nonisotopic high resolution in situ hybridization technique. Chromosome identification following in situ hybridization was possible by counterstaining of the same preparation with Chromomycin A₃, Distamycin A, and DAPI. Using this approach, we have assigned HPV-18 integration in HeLa cells to band 8q24 (a site including the locus of the myc-protooncogene), to an abnormal chromosome 22, and to a not yet identified marker chromosome possibly neighboring other oncogenic or activating sites. The sensitive detection technique described in this study presents a new approach involving in situ chromosome hybridization with biotinylated DNA probes in combination with reflection contrast microscopy and subsequent fluorescent R-and C-banding. The method allowed the assignment of a 7-kb HPV-18 DNA probe to human chromosomal sites important in growth regulation and cancerogenesis. It should prove useful in a number of similar studies using other viral and oncogenic DNA probes.     

Protein is linked to the 5' end of poliovirus RNA by a phosphodiester linkage to tyrosine.

Purification and partial characterization of the poliovirus RNA-linked protein (VPg) are described. VPg has been freed from the RNA by ribonuclease digestion and phenol extraction. Gel filtration chromatography of VPg-pUp (labeled with 32P) in 0.5% sodium dodecyl sulfate or 6 M guanidine HCl indicates that it has a molecular weight of about 12,000. VPg is bound to the 5' end of poliovirion RNA by a phosphodiester bond between a tyrosine residue in the VPg molecule and the 5'-terminal uridine. After acid hydrolysis of [3H]tyrosine-labeled VPg-pU, free tyrosine can be released by venom phosphodiesterase. Acid hydrolysis of VPg-p labeled with either 32P or [3H] tyrosine yields tyrosine-phosphate. There appears to be only 1 tyrosine residue per VPg molecule.     

Separation and quantitation of intracellular forms of poliovirus RNA by agarose gel electrophoresis.

Intracellular poliovirus-specific RNA species can be measured directly by electrophoresis of total cytoplasmic nucleic acids through 1% agarose gels, resulting in the separation of single- and double-stranded forms of poliovirus RNA from each other and from HeLa cell 28S ribosomal RNA. Single-stranded RNA molecules differing by only 15% in length are resolved in this gel system. RNA species can be visualized as fluorescen bands appearing after staining of the gels with ethidium bromide and observation under ultraviolet illumination. The total amount of RNA can be determined by densitometric quantitation of the fluorescent response. In this way, the amount of poliovirus-specific RNA within the cytoplasm of HeLa cells infected for various times has been estimated. At 170-min postinfection, there are 0.67 X 10(5) molecules of single-stranded poliovirus RNA per cell and at 230 min, the amount has increased to 3.7 X 10(5) molecules/cell. Poliovirus double-strnaded RNA reaches a maximum of 0.7 X 10(5) molecules/cell at 330 min after infection.     

MMP-9, TIMP-1 and inflammatory cells in sputum from COPD patients during exacerbation

Background

Irreversible airflow obstruction in Chronic Obstructive Pulmonary Disease (COPD) is thought to result from airway remodelling associated with aberrant inflammation. Patients who experience frequent episodes of acute deterioration in symptoms and lung function, termed exacerbations, experience a faster decline in their lung function, and thus over time greater disease severity However the mechanisms by which these episodes may contribute to decreased lung function are poorly understood.This study has prospectively examined changes in sputum levels of inflammatory cells, MMP-9 and TIMP-1 during exacerbations comparing with paired samples taken prior to exacerbation.

Methods

Nineteen COPD patients ((median, [IQR]) age 69 [63 to 74], forced expiratory volume in one second (FEV1) 1.0 [0.9 to1.2], FEV1% predicted 37.6 [27.3 to 46.2]) provided sputa at exacerbation. Of these, 12 were paired with a samples collected when the patient was stable, a median 4 months [2 to 8 months] beforehand.

Results

MMP-9 levels increased from 10.5 μg/g [1.2 to 21.1] prior to exacerbation to 17.1 μg/g [9.3 to 48.7] during exacerbation (P < 0.01). TIMP-1 levels decreased from 3.5 μg/g [0.6 to 7.8] to 1.5 μg/g [0.3 to 4.9] (P = 0.16). MMP-9/TIMP-1 Molar ratio significantly increased from 0.6 [0.2 to 1.1] to 3.6 [2.0 to 25.3] (P < 0.05). Neutrophil, eosinophil and lymphocyte counts all showed significant increase during exacerbation compared to before (P < 0.05). Macrophage numbers remained level. MMP-9 levels during exacerbation showed highly significant correlation with both neutrophil and lymphocyte counts (Rho = 0.7, P < 0.01).

Conclusion

During exacerbation, increased inflammatory burden coincides with an imbalance of the proteinase MMP-9 and its cognate inhibitor TIMP-1. This may suggest a pathway connecting frequent exacerbations with lung function decline.