Sympathetic hyper-excitation in obesity and pulmonary hypertension: physiological relevance to the 'obesity paradox'.

BACKGROUND: Within the lung, sympathetic nerve activity (SNA) has an important role in facilitating pulmonary vasodilation. As SNA is elevated in obesity, we aimed to assess the impact of sympathetic hyper-excitation on pulmonary vascular homeostasis in obesity, and its potential role in ameliorating the severity of pulmonary hypertension (PH); the well-documented 'obesity paradox' phenomenon. METHODS: Zucker obese and lean rats were exposed to normoxia or chronic hypoxia (CH-10% O2) for 2 weeks. Subsequently, pulmonary SNA (pSNA) was recorded (electrophysiology), or the pulmonary microcirculation was visualized using Synchrotron microangiography. Acute hypoxic pulmonary vasoconstriction (HPV) was assessed before and after blockade of ß1-adrenergic receptors (ARs) (atenolol, 3 mg kg(-1)) and ß1+ß2-adrenergic (propranolol, 2 mg kg(-1)). RESULTS: pSNA of normoxic obese rats was higher than lean counterparts (2.4 and 0.5 µV s, respectively). SNA was enhanced following the development of PH in lean rats, but more so in obese rats (1.7 and 6.8 µV s, respectively). The magnitude of HPV was similar for all groups (for example, ~20% constriction of the 200-300 µm vessels). Although ß-blockade did not modify HPV in lean rats, it significantly augmented the HPV in normoxic obese rats (ß1 and ß2 blockade), and more so in obese rats with PH (ß2-blockade alone). Western blots showed, while the expression of pulmonary ß1-ARs was similar for all rats, the expression of ß2-ARs was downregulated in obesity and PH. CONCLUSIONS: This study suggests that sympathetic hyper-excitation in obesity may have an important role in constraining the severity of PH and, thus, contribute in part to the 'obesity paradox' in PH.

Dual implantation of a radio-telemeter and vascular access port allows repeated hemodynamic and pharmacological measures in conscious lean and obese rats.

Expansion of physiological knowledge increasingly requires examination of processes in the normal, conscious state. The current study describes a novel approach combining surgical implantation of radio-telemeters with vascular access ports (VAPs) to allow repeated hemodynamic and pharmacological measures in conscious rats. Dual implantation was conducted on 16-week-old male lean and obese Zucker rats. Continued viability one month after surgery was observed in 67% of lean and 44% of obese animals, giving an overall 54% completion rate. Over the five-week measurement period, reliable and reproducible basal mean arterial pressure and heart rate measures were observed. VAP patency and receptor-independent vascular reactivity were confirmed by consistent hemodynamic responses to sodium nitroprusside (6.25 µg/kg). Acutely, minimal hemodynamic responses to repeated bolus administration of 0.2 mL saline indicated no significant effect of increased blood volume or administration stress, making repeated acute measures viable. Similarly, repeated administration of the ß-adrenoceptor agonist dobutamine (30 µg/kg) at 10 min intervals resulted in reproducible hemodynamic changes in both lean and obese animals. Therefore, our study demonstrates that this new approach is viable for the acute and chronic assessment of hemodynamic and pharmacological responses in both lean and obese conscious rats. This technique reduces the demand for animal numbers and allows hemodynamic measures with minimal disruption to animals' welfare, while providing reliable and reproducible results over several weeks. In conclusion, dual implantation of a radio-telemeter and VAP introduces a valuable technique for undertaking comprehensive studies involving repeated pharmacological tests in conscious animals to address important physiological questions.

Production and characterization of 22 monoclonal antibodies directed against S 20499, a new potent 5-HT1A chiral agonist: influence of the hapten structure on specificity and stereorecognition.

PURPOSE: An immunoconjugate model was proposed to produce stereoselective monoclonal antibodies (MAbs) for the quantitation of a 5-HT1A agonist, S 20499. MAbs produced were characterized in terms of stereoselectivity and specificity towards the opposite enantiomer and structural analogs. METHODS: The immunogen was formed following the effective addition of a butanoic acid spacer arm between the parent S 20499 structure and bovine serum albumin (BSA). After fusion (modified Köhler and Milstein's procedure), specificity of MAbs was obtained using the Abraham's criteria. Experimental and calculated partition coefficients were determined. RESULTS: Twenty-two hybridoma cell lines were established secreting MAbs (apparent association constants ranging from 1.1 x 10(8) to 2.8 X 10(9) M(-1)). Several MAbs showed cross-reactivity levels of less than 5% with S 20500 (optical antipode), which could allow a stereospecific assay to be set up. Both chroman and azaspiro moieties were part of the epitopic site. Dealkylation and hydroxylation(s) led to various crossreactivity levels. Four antibody families were described in terms of specificity. CONCLUSIONS: This study highlighted the influence of the immunoconjugate construction (coupling site and type of spacer arm) in the immuno-stereospecificity of Abs. The results obtained for two monohydroxylated metabolites suggest that the lipophilicity behavior could be a valuable tool for predicting Ab-crossreactivity.

The path to a clinical pathway: collaborative care for the patient with an ostomy.

A colostomy and ileostomy clinical pathway was developed at a southeastern teaching hospital in 1990 in response to excessive lengths of stay and costs at our hospital compared with national data for this patient group. A multidisciplinary clinical pathway team was formed and charged with the development, implementation, and ongoing monitoring of the clinical pathway tool and its effect on the outcomes of the population of patients with colostomies and ileostomies. Through this multidisciplinary collaboration, length of stay and cost have been reduced while quality care indicators have been maintained. This article presents the sample pathway we developed and describes the pathway development process, documentation, the variance analysis process, and the outcomes achieved with implementation. A urostomy/urinary diversion pathway that was developed after variance analysis review of the colostomy and ileostomy clinical pathway is also presented.