Pelvic and Lower Gastrointestinal Tract Anatomical Characterization of the Average Male.

OBJECTIVE: Colorectal surgeons report difficulty in positioning surgical devices in males, particularly those with a narrower pelvis. The objectives of this study were to (1) characterize the anatomy of the pelvis and surrounding soft tissue from magnetic resonance and computed tomography scans from 10 average males (175 cm, 78 kg) and (2) develop a model representing the mean configuration to assess variability. METHODS: The anatomy was characterized from existing scans using segmentation and registration techniques. Size and shape variation in the pelvis and soft tissue morphology was characterized using the Generalized Procrustes Analysis to compute the mean configuration. RESULTS: There was considerable variability in volume of the psoas, connective tissue, and pelvis and in surface area of the mesorectum, pelvis, and connective tissue. Subject height was positively correlated with mesorectum surface area (P = .028, R2 = 0.47) and pelvis volume ( P = .041, R2 = 0.43). The anterior-posterior distance between the inferior pelvic floor muscle and pubic symphysis was positively correlated with subject height ( P = .043, r = 0.65). The angle between the superior mesorectum and sacral promontory was negatively correlated with subject height ( P = .042, r = -0.65). The pelvic inlet was positively correlated with subject weight ( P = .001, r = 0.89). CONCLUSIONS: There was considerable variability in organ volume and surface area among average males with some correlations to subject height and weight. A physical trainer model created from these data helped surgeons trial and assess device prototypes in a controllable environment.

Wireless capsule endoscopy color video segmentation.

This paper describes the use of color image analysis to automatically discriminate between oesophagus, stomach, small intestine, and colon tissue in wireless capsule endoscopy (WCE). WCE uses "pill-cam" technology to recover color video imagery from the entire gastrointestinal tract. Accurately reviewing and reporting this data is a vital part of the examination, but it is tedious and time consuming. Automatic image analysis tools play an important role in supporting the clinician and speeding up this process. Our approach first divides the WCE image into subimages and rejects all subimages in which tissue is not clearly visible. We then create a feature vector combining color, texture, and motion information of the entire image and valid subimages. Color features are derived from hue saturation histograms, compressed using a hybrid transform, incorporating the discrete cosine transform and principal component analysis. A second feature combining color and texture information is derived using local binary patterns. The video is segmented into meaningful parts using support vector or multivariate Gaussian classifiers built within the framework of a hidden Markov model. We present experimental results that demonstrate the effectiveness of this method.

Surgical exposure and anatomy of the female pelvis.

Female pelvic anatomy encompasses the reproductive, urologic, and gastrointestinal systems. Knowledge of the inherent relations between these organ systems, as well as the ability to develop pelvic spaces, will enable the surgeon to approach pelvic pathology confidently. This article highlights basic anatomy of the female pelvis and emphasizes points of caution during pelvic surgery, as well as reviews the essential principles of pelvic support.

Endocrine regulation of ion transport in the avian lower intestine.

The lower intestine (colon and coprodeum) of the domestic fowl maintains a very active, transporting epithelium, with a microvillus brush border, columnar epithelial cells, and a variety of transport systems. The colon of normal or high salt-acclimated hens expresses sodium-linked glucose and amino acid cotransporters, while the coprodeum is relatively inactive. Following acclimation to low salt diets, however, both colon and coprodeum shift to a pattern of high expression of electrogenic sodium channels, and the colonic cotransporter activity is simultaneously downregulated. These changes in the transport patterns seem to be regulated, at least in part, by aldosterone. Our recent work with this tissue has focused on whether aldosterone alone can account for the low salt pattern of transport. Other work has looked at the changes in morphology and in proportions of cell types that occur during chronic acclimation to high or low salt diets, and on a cAMP-activated chloride secretion pathway. Recent findings suggesting effects of other hormones on lower intestinal transport are also presented.

A physiologically based toxicokinetic model for dietary uptake of hydrophobic organic compounds by fish: I. Feeding studies with 2,2',5,5'-tetrachlorobiphenyl.

A physiologically based toxicokinetic (PBTK) model was developed to describe dietary uptake of hydrophobic organic compounds by fish. The gastrointestinal (GI) tract was modeled using four compartments corresponding to the stomach, pyloric ceca, upper intestine, and lower intestine, and the lumenal volume of each compartment was allowed to change in time as a function of bulk flow down the GI tract and (for the pyloric ceca and upper intestine) nutrient uptake. The model was developed using data from rainbow trout that were fed a single meal of 60-day-old fathead minnows contaminated with [UL-(14)C] 2,2',5,5'-tetrachlorobiphenyl ([(14)C] PCB 52). Chemical partitioning coefficients for the gut contents and tissues were adjusted to account for changes in chemical affinity associated with uptake of dietary lipid. Permeability constants for the absorbing gut segments were then fitted by modeling to measured [(14)C] PCB 52 concentrations in gut contents and tissues. The model accurately describes observed patterns of gastric evacuation and bulk flow of digesta, the concentration time course for [(14)C] PCB 52 in contents and tissues of the GI tract, and [(14)C] PCB 52 distribution to other major tissues. Most of the [(14)C] PCB 52 was taken up in the pyloric ceca and upper intestine during the period of peak lipid absorption. It is concluded, however, that a kinetic limitation acting along the entire length of the GI tract resulted in a chemical disequilibrium between feces and tissues of the lower intestine.