Invited commentary

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41288/1/268_2005_Article_BF01658533.pd

Blood flow and distribution in the canine pancreas

Because of a tripartite arterial inflow, accurate determination of canine pancreatic blood flow (Qp) in experimental studies remains problematic. Assessment of blood flow using a single electromagnetic flow probe on the anterior pancreaticoduodenal artery (APDA) was compared to the radiolabeled microsphere method. Distribution of Qp was based on microsphere density. Qp determined simultaneously with the flow probe technique and the microsphere method were 86 +/- 17 and 23 +/- 8 ml/min, respectively, (P Qp measured by the flow probe increased to 94 +/- 27 ml/min (NS) and decreased to 19 +/- 4 ml/min (NS) using microspheres. Intrapancreatic distribution of Qp was not significantly altered by occlusion of the SA and PPDA. Intrapancreatic arterial collateral is adequate to maintain blood flow to the entire pancreas even when arterial inflow is restricted to the APDA. Flow probe determinations of Qp are artifactually high because they include flow to the duodenum and may also be subject to methodologic error.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26591/1/0000132.pd

Pancreatico-portal dissociation: A canine model to evaluate the hepatic maintenance effects of partial portal flow diversion and pancreatic hormone deprivation

Pancreatico-portal dissociation provides a viable canine experimental model for evaluating the effects of portal flow reduction and pancreatic hormone deprivation in liver mainenance. Initial studies indicate flow as a "vehicle" for substrate (and/or hormone) delivery and imply a possible contribution to hepatic maintenance of the gastrosplenic venous axis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23638/1/0000602.pd

Differential effects of portal diversion on hepatocyte function (HF) and hepatic reticuloendothelial cell (HRES) activity in the dog

End-to-side portocaval shunts (PCS) were constructed in six dogs to evaluate the effect of complete portal blood flow diversion on hepatocellular structure and function, hepatic reticuloendothelial (RE) activity, and serum opsonic activity (OA). RE activity remained normal after PCS despite a 40% reduction in estimated hepatic blood flow. Tissue distribution of injected colloid shifted away from liver to spleen, lung, and bone marrow. OA decreased to 40% of baseline values 6 weeks after PCS and remained low. Postshunt changes in hepatic morphology primarily affected hepatocytes and included deglycogenation and loss of rough endoplasmic reticulum. Significant changes in Kupffer cell morphology were not observed. Complete portal flow diversion in the dog caused profound alterations in hepatocellular structure and function without compromising Kupffer cell phagocytic and metabolic activity. Kupffer cells may be less dependent than hepatocytes upon hepatotrophic factors contained in portal blood. OA did not correlate with changes in vascular lipid clearance, suggesting that either phagocytosis of RES test lipid in the dog is not dependent on prior opsonization, or that the assay used was neither sensitive nor specific enough to measure a critical opsonic threshold required for effective phagocytosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23877/1/0000116.pd

Low molecular weight dextran in experimental pancreatitis: Effects on pancreatic microcirculation

Although low molecular weight (LMW) dextran has been said to decrease the lethality of experimental acute pancreatitis (AP) by reversing stasis in the pancreatic microcirculation, the actual mechanism(s) of action is unknown. This investigation was designed to measure the effects of low molecular weight dextran on pancreatic capillary flow (QCAP) and arteriovenous shunt flow (QAVS), and on pancreatic oxygen consumption (O2CP) following bile-trypsin-induced AP in dogs. Total pancreatic blood flow (QT) was measured with an electromagnetic flow probe on the superior pancreaticoduodenal artery (SPDA). QAVS was measured by liver trapping of 99mTc-albumin microspheres after SPDA injection. QCAP was calculated as QT minus QAVS. Seventeen dogs were treated with lactated Ringer's (LR) solution at 6.5 ml/kg/hr; 10 dogs were treated with LMW dextran 10% in normal saline at 1.5 ml/kg/hr plus LR at 5.0 ml/kg/hr. Mean arterial and central venous pressures remained constant throughout the 4-hr experiment. In the dogs receiving LR only, QT decreased from 42.7 to 24.4 ml/min (P QAVS remained constant at 1.35 +/- 0.04 ml/min. During the first 30 min O2CP decreased from 1.17 to 0.76 ml O2/min (P QT and QCAP without altering QAVS. The decrease in O2CP in association with a constant QAVS suggests a metabolic block to oxygen uptake at the cellular level. Continuous infusion of LMW dextran at a dose of 1.5 ml/kg/hr in the dog does not reverse these abnormalities.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25168/1/0000606.pd

Pancreatic response to crystalloid resuscitation in experimental pancreatitis

Restoration and maintenance of intravascular volume is crucial in acute pancreatitis to prevent hypotension and ensure normal organ perfusion. This study evaluated the hemodynamic and metabolic effects of adequate versus inadequate fluid replacement on the pancreas in a canine model of acute experimental pancreatitis. Bile-trypsin pancreatitis (BTP) was induced in 14 conditioned mongrel dogs. Lactated Ringer's solution was administered intravenously at high (HIR) and low (LIR) infusion rates (6.5 and 1.75 ml/kg/hr, respectively) to 7 dogs each for 4 h. Seven sham-operated controls (CON) received lactated Ringer's at 6.5 ml/kg/hr for 3 hr. Mean arterial pressure remained unchanged in all groups. Central venous pressure decreased in the LIR group (P P QP) decreased in the LIR group (73%) to a significantly greater extent than in the HIR (23%) and CON (8%) groups, and in the HIR group significantly more than in the CON group. The fall in pancreatic oxygen consumption (O2CP) in both the pancreatitis groups was significant compared to the rise in the CON group. Final changes in QP and O2CP from baseline were significant only in the LIR group. We conclude that inadequate crystalloid replacement after BTP results in a progressive fall in QP and O2CP. Vigorous fluid replacement incompletely prevents these effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26524/1/0000063.pd

Effects of portacaval shunt and portacaval transposition on hepatocellular and hepatic reticuloendothelial cell activity in the dog

Quantitative reduction of portal blood flow following a portacaval shunt (PCS) adversely affects hepatocyte function, but does not alter HRES activity[1.]. To determine whether similar changes occur after qualitative alteration of portal blood flow, portacaval transpositions (PCT) were constructed in six conditioned mongrel dogs. Estimated hepatic blood flow (EHBF) was determined scintigraphically by the rate of hepatic uptake of a 500-[mu]Ci dose of 99mTc-sulfur colloid (Tsc). Hepatic reticuloendothelial cell (RES) phagocytic (PI) and degradative (DI) indices were calculated from the half-time blood disappearance of 131I-labeled RES test lipid emulsion, and the half-time urine appearance of free 131I, respectively. Opsonic activity (OI) was determined by gelatin latex particle agglutination and normalized to control values. Hepatocellular function was assessed by serial determinations of albumin (Alb), and pyruvic and glutamic oxaloacetic transaminases (SGPT and SGOT). All studies were performed prior to and at 3, 6, and 9 weeks following PCS or PCT. Conclusions: In the dog, neither PCS nor PCT adversely affected HRES activity. Hepatocellular function and OI remained unchanged following PCT but deteriorated significantly after PCS. Observed changes in hepatocyte function and OI following PCS suggest that hepatocellular integrity and serum opsonic activity may be interrelated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24838/1/0000264.pd

EXPLICIT: a feasibility study of remote expert elicitation in health technology assessment

This is the final version of the article. Available from BioMed Central via the DOI in this recordBACKGROUND: Expert opinion is often sought to complement available information needed to inform model-based economic evaluations in health technology assessments. In this context, we define expert elicitation as the process of encoding expert opinion on a quantity of interest, together with associated uncertainty, as a probability distribution. When availability for face-to-face expert elicitation with a facilitator is limited, elicitation can be conducted remotely, overcoming challenges of finding an appropriate time to meet the expert and allowing access to experts situated too far away for practical face-to-face sessions. However, distance elicitation is associated with reduced response rates and limited assistance for the expert during the elicitation session. The aim of this study was to inform the development of a remote elicitation tool by exploring the influence of mode of elicitation on elicited beliefs. METHODS: An Excel-based tool (EXPLICIT) was developed to assist the elicitation session, including the preparation of the expert and recording of their responses. General practitioners (GPs) were invited to provide expert opinion about population alcohol consumption behaviours. They were randomised to complete the elicitation by either a face-to-face meeting or email. EXPLICIT was used in the elicitation sessions for both arms. RESULTS: Fifteen GPs completed the elicitation session. Those conducted by email were longer than the face-to-face sessions (13 min 30 s vs 10 min 26 s, p = 0.1) and the email-elicited estimates contained less uncertainty. However, the resulting aggregated distributions were comparable. CONCLUSIONS: EXPLICIT was useful in both facilitating the elicitation task and in obtaining expert opinion from experts via email. The findings support the opinion that remote, self-administered elicitation is a viable approach within the constraints of HTA to inform policy making, although poor response rates may be observed and additional time for individual sessions may be required.This paper presents independent research funded by the National Institute of Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) for the South West Peninsula

A comparison of dietary patterns derived by cluster and principal components analysis in a UK cohort of children

Background/Objectives: The objective of this study was to identify dietary patterns in a cohort of 7-year-old children through cluster analysis, compare with patterns derived by principal components analysis (PCA), and investigate associations with sociodemographic variables. Subjects/Methods: The main caregivers in the Avon Longitudinal Study of Parents and Children (ALSPAC) recorded dietary intakes of their children (8279 subjects) using a 94-item food frequency questionnaire. Items were then collapsed into 57 food groups. Dietary patterns were identified using k-means cluster analysis and associations with sociodemographic variables examined using multinomial logistic regression. Clusters were compared with patterns previously derived using PCA. Results: Three distinct clusters were derived: Processed (4177 subjects), associated with higher consumption of processed foods and white bread, Plant-based (2065 subjects), characterized by higher consumption of fruit, vegetables and non-white bread, and Traditional British (2037 subjects), associated with higher consumption of meat, vegetables and full-fat milk. Membership of the Processed cluster was positively associated with girls, younger mothers, snacking and older siblings. Membership of the Plant-based cluster was associated with higher educated mothers and vegetarians. The Traditional British cluster was associated with council housing and younger siblings. The three clusters were similar to the three dietary patterns obtained through PCA; each principal component score being higher on average in the corresponding cluster.Conclusions:Both cluster analysis and PCA identified three dietary patterns very similar both in the foods associated with them and sociodemographic characteristics. Both methods are useful for deriving meaningful dietary patterns. © 2011 Macmillan Publishers Limited All rights reserved

Interaction between Education and Household Wealth on the Risk of Obesity in Women in Egypt

Obesity is a growing problem in lower income countries particularly among women. There are few studies exploring individual socioeconomic status indicators in depth. This study examines the interaction of education and wealth in relation to obesity, hypothesising that education protects against the obesogenic effect of wealth