Octreotide increases thresholds of colonic visceral perception in IBS patients without modifying muscle tone

Effects of octreotide (1.25 µg/kg subcutaneously) on colonic tone and visceral perception were evaluated in 10 IBS patients, using a barostat and compared to placebo in a double-blind crossover study. Colonic sensory thresholds were also studied in healthy controls for comparison with IBS patients. Colonic tone was reflected by variations in volume of the barostat balloon. Baseline volume was 117±38 ml and was not modified by placebo (122±40 ml) or octreotide (106±42 ml). After the meal, maximal decrease in balloon volume was 75±4% following placebo (P<0.001) beginning after 9±3 min and lasting 136±17 min. Following octreotide, the maximal decrease was 69±16% (NS vs placebo), after 10±3 min and lasting 140±22 min. In the second part, discomfort and pain thresholds were evaluated during isobaric distensions (4 mm Hg increments, 5-min duration, 5-min interval with return to pressure 0 between each). The pressure inducing discomfort was 21.2±5.9 mm Hg following placebo vs 29.6±6.6 mm Hg following octreotide (P<0.01). The pressure inducing pain was 24.8±7.3 mm Hg following placebo vs 33.2±7.3 mm Hg following octreotide (P<0.01). In healthy subjects, discomfort and pain were induced by colonic distensions at a mean intraballoon pressure of 32.7±5.8 mm Hg and 36.7±3.9 mm Hg, respectively. Compliance curves were not different following placebo and octreotide. Octreotide significantly increases thresholds for visceral perception in IBS patients without modifying compliance during distension nor colonic tone.     

A new finite element approach for near real‐time simulation of light propagation in locally advanced head and neck tumors

Background and Objectives

Several clinical studies suggest that interstitial photodynamic therapy (I‐PDT) may benefit patients with locally advanced head and neck cancer (LAHNC). For I‐PDT, the therapeutic light is delivered through optical fibers inserted into the target tumor. The complex anatomy of the head and neck requires careful planning of fiber insertions. Often the fibers' location and tumor optical properties may vary from the original plan therefore pretreatment planning needs near real‐time updating to account for any changes. The purpose of this work was to develop a finite element analysis (FEA) approach for near real‐time simulation of light propagation in LAHNC.

Methods

Our previously developed FEA for modeling light propagation in skin tissue was modified to simulate light propagation from interstitial optical fibers. The modified model was validated by comparing the calculations with measurements in a phantom mimicking tumor optical properties. We investigated the impact of mesh element size and growth rate on the computation time, and defined optimal settings for the FEA. We demonstrated how the optimized FEA can be used for simulating light propagation in two cases of LAHNC amenable to I‐PDT, as proof‐of‐concept.

Results

The modified FEA was in agreement with the measurements (P = 0.0271). The optimal maximum mesh size and growth rate were 0.005–0.02 m and 2–2.5 m/m, respectively. Using these settings the computation time for simulating light propagation in LAHNC was reduced from 25.9 to 3.7 minutes in one case, and 10.1 to 4 minutes in another case. There were minor differences (1.62%, 1.13%) between the radiant exposures calculated with either mesh in both cases.

Conclusions

Our FEA approach can be used to model light propagation from diffused optical fibers in complex heterogeneous geometries representing LAHNC. There is a range of maximum element size (MES) and maximum element growth rate (MEGR) that can be used to minimize the computation time of the FEA to 4 minutes. Lasers Surg. Med. 47:60–67, 2015. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.     

Biochemical Markers for Alcoholism

A panel of blood tests, purportedly markers for alcohol abuse, were examined in 543 relatively healthy alcoholics entering ambulatory rehabilitation treatment. Individual tests were too low in sensitivity: gamma-glutamyl transpeptidase was abnormally high in only 49%, then mean corpuscular volume (45%), high density lipoprotein cholesterol (HDLC) (25%), serum glutamic oxaloacetic transaminase (SGOT) (28%), and blood alcohol (21%). HDLC was of low sensitivity, generally unaffected by liver disease, and related to quantitation of recent alcohol consumed. Combining seven markers, 82% of males and 71% females had at least one abnormally high value. Histories of heavy recent drinking, positive blood alcohol levels on admission, and manifest liver disease on physical examination or by hyperbilirubinemia were associated with high sensitivities of individual and pooled markers. The biochemical markers studied can be useful to suggest alcohol abuse, especially in some populations of drivers. In other populations of alcoholics, especially with intermittent alcohol or recent abstinence, their sensitivities were so low as to discourage extensive reliance on their use. The diagnosis of alcoholism continues to depend on clinical history of alcohol-related problems, including social, familial, legal, medical, psychological, and economic.     

Development of isolated perfused whole stomach for motility study in rat and cat

An isolatedex vivo perfused mammalian stomach preparation is an ideal model for the study of motility avoiding central nervous influence and circulating humoral factors. In this paper, we describe the technique of such preparation in two different species: rat and cat, and its implication for motility study. While the isolated stomach was perfused with Krebs-Ringer solution via celiac artery, motility of the antrum was recorded using an open-tip tube in rats and a bipolar platinum electrode and a strain gauge in cats. The spontaneous antral motility and its response to drugs, such as dopamine and domperidone proved that the preparation would be a useful model to study motility devoid of influences of the central nervous system and circulating humoral agents.Dr. S.K. Odaibo was supported by a special postdoctoral clinical research fellowship award PG/256/168 from the University of Ilorin, Ilorin, Nigeria.Presented in part at the American Gastroenterological Association Meeting, Washington, DC, May 1983.