Aptamer based peptide enrichment for quantitative analysis of gonadotropin-releasing hormone by LC-MS/MS.

Over recent years threats to racing have expanded to include naturally occurring biological molecules, such as peptides and proteins, and their synthetic analogues. Traditionally, antibodies have been used to enable detection of these compounds as they allow purification and concentration of the analyte of interest. The rapid expansion of peptide-based therapeutics necessitates a similarly rapid development of suitable antibodies or other means of enrichment. Potential alternative enrichment strategies include the use of aptamers, which offer the significant advantage of chemical synthesis once the nucleic acid sequence is known. A method was developed for the enrichment, detection and quantitation of gonadotropin-releasing hormone (GnRH) in equine urine using aptamer-based enrichment and LC-MS/MS. The method achieved comparable limits of detection (1 pg/mL) and quantification (2.5 pg/mL) to previously published antibody-based enrichment methods. The intra- and inter-assay precision achieved was less than 10% at both 5 and 20 pg/mL, and displayed a working dynamic range of 2.5-100 pg/mL. Significant matrix enhancement (170 ± 8%) and low analytical recovery (29 ± 15%) was observed, although the use of an isotopically heavy labelled GnRH peptide, GnRH (Pro(13)C5,(15)N), as the internal standard provides compensation for these parameters. Within the current limits of detection GnRH was detectable up to 1h post administration in urine and identification of a urinary catabolite extended this detection window to 4h. Based on the results of this preliminary investigation we propose the use of aptamers as a viable alternative to antibodies in the enrichment of peptide targets from equine urine.

Can Horton hear the whos? The importance of scale in mosquito-borne disease.

The epidemiology of vector-borne pathogens is determined by mechanisms and interactions at different scales of biological organization, from individual-level cellular processes to community interactions between species and with the environment. Most research, however, focuses on one scale or level with little integration between scales or levels within scales. Understanding the interactions between levels and how they influence our perception of vector-borne pathogens is critical. Here two examples of biological scales (pathogen transmission and mosquito mortality) are presented to illustrate some of the issues of scale and to explore how processes on different levels may interact to influence mosquito-borne pathogen transmission cycles. Individual variation in survival, vector competence, and other traits affect population abundance, transmission potential, and community structure. Community structure affects interactions between individuals such as competition and predation, and thus influences the individual-level dynamics and transmission potential. Modeling is a valuable tool to assess interactions between scales and how processes at different levels can affect transmission dynamics. We expand an existing model to illustrate the types of studies needed, showing that individual-level variation in viral dose acquired or needed for infection can influence the number of infectious vectors. It is critical that interactions within and among biological scales and levels of biological organization are understood for greater understanding of pathogen transmission with the ultimate goal of improving control of vector-borne pathogens.

In vitro and in vivo effects of West Nile virus propagated in cells of different passage.

Tissue cultures are used to propagate viruses for use in mosquito infection studies and to detect live virus in field-collected specimens. Microscopic evaluation of cytopathic effects is used to visualize virus presence. In this study, both low-passage (LP; n = 35) and high-passage (HP; n = 218) lines of African green monkey kidney (Vero) cells were infected with West Nile virus, and virus growth kinetics were quantitated over different incubation periods (IPs) (2, 6, 10, 24, 48, 72, and 96 h postinfection). Virus titers were significantly (P < 0.05) higher in the HP compared with LP line 24, 48, and 96 h postinfection. No differences were observed in plaque morphology between the LP and HP lines. Culex pipiens quinquefasciatus were fed infectious blood meals created using supernatant from the 2 lines and maintained at 28 degrees C for a 12-day IP. Although the virus dose was higher (P < 0.05) in the HP compared with the LP line, there were no significant differences in mosquito infection or dissemination rates at the end of the IP. The significance of these observations for assessing virus presence and pathogenicity is discussed.

Pelvic arteriovenous malformation mimicking seminal vesicle cyst.

Congenital pelvic arteriovenous malformations are rare entities, especially in males. Presenting symptoms, if any at all, are commonly a mass, thrill, bruit, or pain. Treatment options include surgical extirpation, embolization, or a combination of both. This case provides support for the last option in a patient presenting with symptoms localized to the seminal vesicles.

[Detailed evaluation of sexual function after radical prostatectomy: is patient satisfaction correlated with the quality of erections?]. / Evaluation détaillée de la fonction sexuelle après prostatectomie radicale: la satisfaction des patients est-elle corrélée à la qualité des érections?

INTRODUCTION: Post radical prostatectomy potency rates, quantified on the basis of physician survey, have ranged up to 80%. Physician derived potency data, however, may not be representative of true post-prostatectomy potency rates or more importantly may not accurately portray patients' post-operative sexual satisfaction. We conducted a pilot study combining physician derived and patient derived subjective data with objective measures of erectile function. MATERIALS AND METHODS: Eleven men, mean age of 59 years, who were treated with nerve sparing radical retropubic prostatectomy formed the study group. Initially, the patients responded to a physician directed telephone survey on sexual status. Potency was then objectively assessed utilizing Rigiscan testing on two consecutive evenings. Lastly, the patients completed a validated short questionnaire directed to obtain a patients' subjective perception of sexual function. RESULTS: All the patients responded to the first part of the study by informing the physician that they were sexually active or potent after radical prostatectomy. Of these 11 patients, however, only 2 (18%) were mostly satisfied with their sex life according to the quality of life questionnaire. Rigiscan testing revealed that 8 of the 11 patients had nocturnal erections which were adequate for vaginal penetration. Of the 5 patients who stated that they were mostly dissatisfied with their sexual functioning, 3 had objective evidence of adequate erectile ability as documented by Rigiscan. Three of the four patients who were ambivalent with respect to their sexual function also demonstrated objective evidence of normal erectile activity. CONCLUSION: Although a patient may inform his care provider that he is sexually active or potent, he may not be satisfied with his present level of sexual functioning. In addition, we observed that some dissatisfied patients do have normal Rigiscan patterns indicating that a percentage of patients who are not happy with their level of sexual function after radical prostatectomy may have a psychogenic component to their problem.