Sorbin in the porcine gastrointestinal tract and pancreas: an immunocytochemical analysis.

Sorbin is a 153-amino acid peptide that was initially discovered in the porcine duodenum. We have reported previously that this peptide regulates intestinal electrolyte transport and have described accumulation sites in the rat digestive tract. In the present study, we investigated the anatomical distribution and the site(s) of sorbin production in the porcine digestive tract using immunocytochemistry. The use of polyclonal antisera, which by cross-reaction studies were shown to be specific for different regions of the molecule, revealed a diversified distribution. Sorbin predominated in endocrine cells preferentially localized in the pyloric glands, duodenal crypts of Lieberkühn, and pancreatic islets; in the gastrointestinal tract, sorbin coexisted with Met-enkephalin or with substance P in a small fraction of serotonin-storing [enterochromaffin (ED)] cells, i.e. EC2 cells and EC1 cells, respectively; in the pancreas, sorbin coexisted with insulin in the beta-cells, also considered as serotonin-storing cells in the pig, and with EC cells in the exocrine pancreas. An enteric neuronal system containing sorbin was also reported. Our results demonstrate that sorbin is a component of the serotonin-storing cell type in the porcine gastrointestinal tract and pancreas, and suggest potential directions to investigate the functions of this new regulatory peptide.

Pharmacokinetics and organ distribution of the sorbin C-terminal peptides.

Sorbin is a 153 amino acid peptide isolated from porcine small intestine. The heptapeptide-amide is the minimal active site of the natural molecule. A comparison of the distribution of C-7 and C-20 sorbin, which have been shown to share the activity of sorbin in increasing intestinal absorption of electrolytes, was undertaken by radioimmunoassay, after perfusion of 200 micrograms/kg/h. A longer half-life in plasma was observed for C-20 sorbin than for C-7 sorbin, with a clearance rate of 18 +/- 4 ml/min/kg vs. 40.6 +/- 13.5 ml/min/kg and a distribution volume of 192 +/- 35 ml/kg vs. 286 +/- 123 ml/kg. The accumulation of tritiated C-7 sorbin was observed in enterocytes, serosal acini of the salivary glands, and fundus chief cells. The recovery of intact peptide in the intestine was 0.06% per gram of tissue. Eighteen percent of the peptide was detected in urine.

Extracorporeal high-intensity focused ultrasound for VX2 liver tumors in the rabbit.

High-Intensity Focused Ultrasound (HIFU) can produce radical tissue necrosis. We wanted to assess tumor destruction, proliferation, and tumorigenesis after HIFU, in an animal model of hepatic tumor. New Zealand rabbits bearing VX-2 solitary liver tumors were treated with extracorporeal HIFU under ultrasound (US) guidance and standardized conditions. Groups differed only for the administration of either one or two consecutive HIFU procedures. Tissue destruction was assessed by stereomicroscopy and planimetry, cell proliferation was estimated by in vivo intra-arterial injection of 1200 muCi [3H]thymidine, and tumorigenesis was tested by reimplantation of treated or untreated pieces of liver tumors into the thighs of nontumor-bearing animals. Mortality was 0. Tumor destruction rates were 76.3% +/- 16% after one procedure and 94.2% +/- 7.3% after two procedures. Nuclear staining was heavy in control tumors and was absent in treated tumors. Untreated hepatic tumors induced measurable tumors at 3 weeks in thighs of all recipients, 7.8 +/- 2.4 cm3 in volume. Hepatic tumors treated with one HIFU procedure induced tumors in the thigh of recipients in 31.3% of cases (0.47 +/- 0.06 cm3), and those treated with two HIFU procedures induced tumors in 0% even after 8 weeks of follow-up. In conclusion, HIFU allows a noninvasive approach to the destruction of liver tumors in this model, with little toxicity but significant effects on proliferation and tumorigenesis. The repetition of HIFU procedures may improve results.

In vivo effects of cavitation alone or in combination with chemotherapy in a peritoneal carcinomatosis in the rat.

Cavitation (volume oscillations and collapse of gas bubbles), as generated by a co-administration of shockwaves (SW) and microbubbles (SWB), induces cytotoxicity in vitro. Moreover, cavitation potentiates the effects of Fluorouracil (FUra) on colon cancer cells. We aimed at reproducing such effects in vivo. A peritoneal carcinomatosis was induced in BDIX rats by intraperitoneal (IP) injection of DHDK12PROb cells. Cavitation was produced by various SW regimens (250 to 750SW) combined with bubbles (air/gelatin emulsion) infused through an IP catheter. In two consecutive experiments, microtumours (day 3 after cell injection) were submitted to various combinations of cavitation and/or Fluorouracil (FUra) and Cisplatinum (CDDP) at either high or low doses. After 30 days, 100% of control animals were dead or presented carcinomatosis with ascites, vs 60% after FUra 5 mg kg dy, day 4 through 8, and 0% after 250 SWB, day 4 and 6 + FUra 5 mg kg dy, day 4 through 8 (P < 0.001); similar differences were found with CDDP. Survival after low dose FUra + SWB was comparable to high dose FUra (25 mg kg dy day through 8) and was improved as compared to low-dose FUra alone. Only a high dose FUra + SWB schedule induced 40% long term (> 150 days) disease-free survival, but also a higher undesirable toxicity (40% toxic deaths within 1 month). It is concluded that cavitation is cytotoxic in vivo and that it potentiates the effects of FUra and CDDP in this animal model.