Transport of protein in the abdominal wall during intraperitoneal therapy. I. Theoretical approach.
(41/508)
Intraperitoneal therapies such as peritoneal dialysis or regional chemotherapy use large volumes of solution within the peritoneal cavity. These volumes increase intraperitoneal hydrostatic pressure (P(ip)), which causes flow of the solution into tissues that surround the cavity. The goal of this paper is to integrate new experimental findings in a rigorous mathematical model to predict protein transport from the cavity into tissue. The model describes non-steady-state diffusion and convection of protein through a deformable porous medium with simultaneous exchange with the microcirculation and local tissue binding. Model parameters are dependent on local tissue pressure, which varies with P(ip). Solute interactions with the tissue in terms of local distribution volume (solute void space), local binding, and retardation relative to solvent flow are demonstrated to be major determinants of tissue concentration profiles and protein penetration from the peritoneal cavity. The model predicts the rate of fluid loss from the cavity to the abdominal wall in dialysis patients to be 94 ml/h, within the observed range of 60-100 ml/h. The model is fitted to published transport data of IgG, and the retardation coefficient f is estimated to be 0.3, which markedly reduces the rate of protein penetration and is far lower than previously published estimates. With the value of f = 0.3, model calculations predict that P(ip) of 4.4 mmHg and dialysis duration of 24 h result in several millimeters of protein penetration into the tissue. (+info)
Evidence for a second valve system in lymphatics: endothelial microvalves.
(42/508)
The mechanism for interstitial fluid uptake into the lymphatics remains speculative and unresolved. A system of intralymphatic valves exists that prevents reflow along the length of the lymphatic channels. However, these valves are not sufficient to provide unidirectional flow at the level of the initial lymphatics. We investigate here the hypothesis that initial lymphatics have a second, separate valve system that permits fluid to enter from the interstitium into the initial lymph channels but prevents escape back out into the tissue. The transport of fluorescent microspheres (0.31 microm) across endothelium of initial lymphatics in rat cremaster muscle was investigated with micropipette manipulation techniques. The results indicate that microspheres can readily pass from the interstitium across the endothelium into the lumen of the initial lymphatics. Once inside the lymphatic lumen, the microspheres cannot be forced out of the lumen even after elevation of the lymphatic pressure by outflow obstruction. Reaspiration of the microspheres inside the lymphatic lumen with a micropipette is blocked by the lymphatic endothelium. This blockade exists whether the aspiration is carried out at the microsphere entry site or anywhere along the initial lymphatics. Nevertheless, puncture of the initial lymphatic endothelium with the micropipette leads to rapid aspiration of intralymphatic microspheres. Investigation of lymphatic endothelial sections fixed during lymph pumping shows open interendothelial junctions not found in resting initial lymphatics. These results suggest that initial lymphatics have a (primary) valve system at the level of the endothelium. In conjunction with the classical (secondary) intralymphatic valves, the primary valves provide the mechanism that facilitates the unidirectional flow during periodic compression and expansion of initial lymphatics. (+info)
Association of airway obstruction, sleep, and phasic abdominal muscle activity after upper abdominal surgery.
(43/508)
We recorded nasal gas flow, sleep stage, and abdominal muscle EMG pattern in 11 patients throughout the night after abdominal surgery, to examine the association between phasic activity of the abdominal muscles, sleep stage, and flow disturbance. We used a miniaturized data logging system, and obtained satisfactory records in eight patients. The data were divided into 30-s epochs. Each epoch was classified as either awake or asleep. The epochs were also classified for the presence of phasic activity in the external oblique abdominal muscle, and for evidence of airway obstruction. Association between these features was tested by a quasi likelihood log linear model. Values given are median (quartiles) for the eight subjects. Sleep occurred for 62 (46-69)% of the study time. During sleep, inspiratory flow was normal for 69 (48-81)% of the time, whereas during wakefulness, the flow pattern was normal for 51 (28-77)% of the time. Phasic activity was present 16 (12-25)% of the time during sleep and 24 (19-37)% of the time during wakefulness (P<0.001). In the awake state, when breathing was normal, phasic activity was present 16 (11-30)% of the time. When breathing was obstructed, phasic activity was present 38 (25-44)% of the time (P<0.001). These surprising findings suggest that sleep may be seriously disturbed by airway obstruction, so that a stable sleep state is not reached. We could not confirm previous findings that disturbed breathing in post-operative patients only occurs during sleep. (+info)
The abdominal wall: an overlooked source of pain.
(44/508)
When abdominal pain is chronic and unremitting, with minimal or no relationship to eating or bowel function but often a relationship to posture (i.e., lying, sitting, standing), the abdominal wall should be suspected as the source of pain. Frequently, a localized, tender trigger point can be identified, although the pain may radiate over a diffuse area of the abdomen. If tenderness is unchanged or increased when abdominal muscles are tensed (positive Carnett's sign), the abdominal wall is the likely origin of pain. Most commonly, abdominal wall pain is related to cutaneous nerve root irritation or myofascial irritation. The pain can also result from structural conditions, such as localized endometriosis or rectus sheath hematoma, or from incisional or other abdominal wall hernias. If hernia or structural disease is excluded, injection of a local anesthetic with or without a corticosteroid into the pain trigger point can be diagnostic and therapeutic. (+info)
Abundant expression of myosin heavy-chain IIB RNA in a subset of human masseter muscle fibres.
(45/508)
Type IIB fast fibres are typically demonstrated in human skeletal muscle by histochemical staining for the ATPase activity of myosin heavy-chain (MyHC) isoforms. However, the monoclonal antibody specific for the mammalian IIB isoform does not detect MyHC IIB protein in man and MyHC IIX RNA is found in histochemically identified IIB fibres, suggesting that the IIB protein isoform may not be present in man; if this is not so, jaw-closing muscles, which express a diversity of isoforms, are likely candidates for their presence. ATPase histochemistry, immunohistochemistry polyacrylamide gel electrophoresis and in situ hybridization, which included a MyHC IIB-specific mRNA riboprobe, were used to compare the composition and RNA expression of MyHC isoforms in a human jaw-closing muscle, the masseter, an upper limb muscle, the triceps, an abdominal muscle, the external oblique, and a lower limb muscle, the gastrocnemius. The external oblique contained a mixture of histochemically defined type I, IIA and IIB fibres distributed in a mosaic pattern, while the triceps and gastrocnemius contained only type I and IIA fibres. Typical of limb muscle fibres, the MyHC I-specific mRNA probes hybridized with histochemically defined type I fibres, the IIA-specific probes with type IIA fibres and the IIX-specific probes with type IIB fibres. The MyHC IIB mRNA probe hybridized only with a few histochemically defined type I fibres in the sample from the external oblique; in addition to this IIB message, these fibres also expressed RNAs for MyHC I, IIA and IIX. MyHC IIB RNA was abundantly expressed in histochemical and immunohistochemical type IIA fibres of the masseter, together with transcripts for IIA and in some cases IIX. No MyHC IIB protein was detected in fibres and extracts of either the external oblique or masseter by immunohistochemistry, immunoblotting and electrophoresis. Thus, IIB RNA, but not protein, was found in the fibres of two different human skeletal muscles. It is believed this is the first report of the substantial expression of IIB mRNA in man as demonstrated in a subset of masseter fibres, but rarely in limb muscle, and in only a few fibres of the external oblique. These findings provide further evidence for the complexity of myosin gene expression, especially in jaw-closing muscles. (+info)
Significant abdominal wall hematoma from an umbilical port insertion.
(46/508)
Laparoscopists consider the umbilical and ventral midline area to be "vascular safe." On occasion, however, the insertion of the first trocar at the umbilical port may result in severe abdominal wall hematoma. (+info)
Videolaparoscopic cholecystectomy. Analysis of the clinical and functional aspects of mechanical lifting of the abdominal wall.
(47/508)
BACKGROUND: Mechanical lifting of the abdominal wall, a method based on traction and consequent elevation of the abdominal wall, is an alternative procedure to create enough intra-abdominal space necessary for videolaparoscopic surgery, dispensing the need for intraperitoneal gas insufflation. OBJECTIVE: This study aims to evaluate the technical feasibility of this procedure to carry out a videolaparoscopic cholecystectomy, while analyzing the clinical and functional aspects of this technique. PATIENTS AND METHODS: In the Digestive Tract Surgery Discipline of the Medical School at the University of Sao Paulo, Sao Paulo, SP, Brazil, was created the equipment to perform videolaparoscopic surgery using this method. The equipment has two sections: an external part which consisted of a frame attached to the operating table, inside which there is a sliding steel cable, moved by a ratched which is located at the lower end of one of the frame rods; the internal rod, the support, has an "L" shape, and its horizontal branch is made up of three turning rods and which is connected to the steel cable after insertion into the abdominal cavity. Ten patients underwent videolaparoscopic cholecystectomy using this equipment. The time taken to install the equipment, the operating area characteristics, the interference from the lifting equipment on surgical movements and on the intra-operative cholangiography, the measurements made of the force used during traction and extension of the abdominal wall elevation, and the medication required for postoperative analgesia were all evaluated. RESULTS: There were no intra-operative complications, and in none of the cases was it found necessary to convert to open surgery. We considered the insertion a safe and uncomplicated procedure, and the traction system efficient. Apart from the elevation of the abdominal wall, the distribution of the viscera inside the abdominal cavity is fundamental for the operating area. Depending on the position of the epigastric trocar, the lifting equipment can interfere with the surgical instruments mobility. It may be necessary to reposition the support to perform the intra-operative cholangiography. The tensional force applied to the peritoneal surface by the lifting rods is small, and no additional postoperative pain was observed using this procedure. CONCLUSION: These results show that using the equipment described in this study, mechanical lifting of the abdominal wall is a feasible alternative for undertaking videolaparoscopic cholecystectomy. (+info)
Groin injuries in athletes.
(48/508)
Groin injuries comprise 2 to 5 percent of all sports injuries. Early diagnosis and proper treatment are important to prevent these injuries from becoming chronic and potentially career-limiting. Adductor strains and osteitis pubis are the most common musculoskeletal causes of groin pain in athletes. These two conditions are often difficult to distinguish. Other etiologies of groin pain include sports hernia, groin disruption, iliopsoas bursitis, stress fractures, avulsion fractures, nerve compression and snapping hip syndrome. (+info)