A new non-uremic rat model of long-term peritoneal dialysis.

Together with the development of peritoneal dialysis (PD), appropriate animal models play an important role in the investigation of physiological, pathophysiological and clinical aspects of PD. However, there is still not an ideal experimental PD animal model. In this study, 45 Sprague-Dawley rats were divided into three groups. Group 1 (n=15) was receiving daily peritoneal injection through the catheter connected to the abdominal cavity, using PD solution containing 3.86 % D-glucose. Group 2 (n=15) was receiving daily peritoneal injection of 0.9 % physiological saline through a catheter. Group 3 (n=15), which was subjected to sham operation, served as controls. Our results showed that WBC counts in peritoneal effluent of Group 1 were slightly higher than those of Group 2 and control group, respectively (p<0.05). However, there was no episode of infection in any group. In addition, there was no significant difference in neutrophils fractions among these three groups. Hematoxylin-eosin and Masson's trichrome staining demonstrated a dramatic increase in thickness of the mesothelium-to-muscle layer of peritoneum exposed to high glucose (Group 1) compared to Group 2 and controls (p<0.01). These data indicated that we established a novel rat model of PD with a modified catheter insertion method. This model is more practical, easy to operate, not too expensive and it will facilitate the investigate of long-term effects of PD.

Prevention of total parenteral nutrition-induced cholestasis by low non-protein energy supply: an animal experiment and clinical study.

30 cecum-ligated rats were divided into 3 groups: group OS fed with stock diet; group HTPN (high-energy total parenteral nutrition) infused with 260 kcal/kg/d of non-protein energy (NPE), which was isoenergetic to the first group; and group LTPN (low-energy total parenteral nutrition) infused with 160 kcal/kg/d. All rats received approximately 1.4 g/kg/d of nitrogen. Positive nitrogen balances were obtained in all 3 groups, although the values were lower in group LTPN. Serum albumin remained normal. Total bilirubin, lipoprotein-X, alkaline phosphatase (AKP), gamma-glutamyl trans-peptidase (gamma-GT) and glutamic-pyruvic transminase (GPT) were significantly lower in group LTPN than in group HTPN. Histological examination with both light and electron microscopy revealed more severe bile stasis in the canaliculi in group HTPN than in group LTPN. In a separate clinical study, lasting more than 4 weeks, two groups of surgical patients received isonitrogenous TPN regimes containing different amounts of energy (40 kcal/kg/d and 30 kcal/kg/d, respectively). 40% of the NPE was infused as fat. The patients were matched for age, clinical condition and nutritional support technique. There were no differences between the groups in nitrogen balance or serum albumin. However serum AKP and gamma-GT increased in the HTPN group after 2 weeks of nutritional support, whilst in the LTPN group the increase did not occur until the fourth week. Our results suggest that TPN-induced cholestasis can be prevented or delayed by reducing the intake of NPE.

Parenteral nutrition support in major abdominal trauma patients.

32 out of 111 patients with major abdominal trauma were studied to evaluate the effects of total parenteral nutrition (TPN). There were 24 men and 8 women with average age of 31 years. 25 cases were recorded as blunt trauma. The others had penetrating wounds. An Abdominal Trauma Index (ATI) was used to score the injury severity. 68% (22 32 ) of the patients had a score of more than 15, and 25% (8 32 ) had a score over 25. TPN was carried out in 11 patients with complicated injuries of the pancreas and duodenum, in 15 cases with small bowel fistula secondary to extended intestinal trauma, and in 6 patients with severe intraabdominal abscesses after injury. The TPN mixture contained 32-42 kcal/kg/day of nonprotein energy and 0.21-0.30 g/kg/day of nitrogen. The average period of TPN support was 26 days. No TPN-related complication developed except 2 cases of catheter-related sepsis. The results demonstrated no significant change in body weight during TPN support. Weekly cumulative nitrogen balances were increased significantly after the use of TPN (from 15.5 g/week at the first week to 48.2 g/week at the fourth week, p < 0.01). There were increases in serum albumin, prealbumin, fibronectin and transferrin following TPN support (from 30.6 g/L, 142.8 mg/L, 103.3 mg/L and 1.2 g/L at day 0 to 35.7 g/L, p < 0.01, 256.3 mg/L, p < 0.01, 184.5 mg/L, p < 0.01, and 1.9 g/L, p < 0.05, at day 21 respectively). Blood sugar, cholesterol and triglyceride remained normal. In 4 patients with duodenal fistula and 6 cases with small bowel fistula (n = 15), the fistulae closed spontaneously. There were no deaths during TPN. We conclude that total parenteral nutrition is of value in the treatment of severe abdominal traumatic patients.

Spectral motion produces an auditory after-effect.

Distortions of perception following prolonged exposure to an unvarying sensory stimulus have been observed since at least the third century BC. The motion after-effect is a familiar experience in which, after a few minutes of viewing objects moving in a single direction, a stationary object appears to move in the opposite direction. Similar after-effects have been observed for many visual stimuli, including tilted lines, colours, stereoscopic depth, curvature, spatial frequency, contrast, rotation and motion in depth. In contrast to the rich variety of visual after-effects reported since the 1960s, reports of analogous auditory adaptation effects only appeared in the 1970s, but have continued since then. Some effects of sound source spatial movement perception after adaptation to a spatially moving sound source have been reported. Here we report an auditory perceptual after-effect analogous to the visual motion after-effect, which is caused by adaptation to auditory spectral (frequency) motion. After a few minutes of listening to a simple spectral pattern moving upwards or downwards in frequency space, the same pattern sounds as though it is drifting in the opposite direction when it is stationary. The effect shows binaural transfer, implying that it is generated at the level after binaural interaction. After-effects produced by the motion of spectral peaks are independent of those produced by spectral notches, suggesting separate processing channels for spectral peaks and notches.

Histopathologic study of cholestasis induced by total parenteral nutrition or intraperitoneal sepsis in rats.

Wistar rats were divided into two groups, intraperitoneal sepsis group (group IS) and total parenteral nutrition group (group TPN), to evaluate the characteristics of pathologic alterations in rats with cholestasis. Biochemical assay showed that cholestasis developed in both groups after 10 days. Light microscopic examination of liver specimens revealed that the degeneration in the intermediate and external zone of hepatolobules was the major alteration in group IS, and group TPN showed characteristic dilation of central veins and hepatic sinuses and the proliferation of Kupffer cells with marked phagocytosis. Electron microscopic pictures presented the enlargement of bile canaliculi with altered microvilli in group IS and many highly electron-dense bile particles within cytoplasm and secondary lysosomes near dilated bile canaliculi in group TPN. It is concluded that there were different histopathologic alterations of liver specimens in TPN-supported animals and septic animals when cholestasis developed. It is unsuitable to take intraperitoneal sepsis as a unique factor of cholestasis in TPN-supported rats. Bile stasis is only one sign of TPN-induced hepatic lesion, which needs further exploration to determine its causes and mechanisms.