Physiologic changes with abdominal wall reconstruction in a porcine abdominal compartment syndrome model.

PURPOSE: Abdominal compartment syndrome (ACS) is a severe complication of ventral hernia repair. The aims of this study were to investigate the effects of intra-abdominal pressure on the physiologic changes of abdominal wall reconstruction and component separation in a porcine model. METHODS: Ventral hernia repair (VHR) was simulated by abdominal fascial imbrication of a 10 × 15 cm defect in 45 Yorkshire pigs assigned to five experimental groups. ACS was simulated by a Stryker endoscopy insufflator with intra-abdominal pressure elevated to 20 mmHg in two groups. Component separation was performed in one of these groups and in one group without ACS. Physiological parameters were measured before and after the procedures and monitored for 4 h. The animals were euthanized for histologic analysis of organ damage. RESULTS: VHR led to an increase in intra-abdominal pressure, bladder pressure, and central venous pressure by an average of 14.89, 13.93, and 14.69 mmHg (p < 0.001) in all animals. Component separation was performed in 25 animals and the three pressures reduced by 9.11, 8.00, 7.89 mmHg (p < 0.001). ACS correlated with higher percentages of large and small bowel necrosis compared to groups without abdominal compartment syndrome. CONCLUSIONS: The results confirm that primary repair of large abdominal wall defects leads to increased intra-abdominal pressure, which can be reduced with component separation. In animals with ACS, component separation may reduce the risk of organ damage. Central venous pressure, bladder pressure, and other physiologic parameters accurately correlated with elevated intra-abdominal pressure and may have utility as markers for diagnosis of ACS.

Reduction of pain-related behaviors with either cold or heat treatment in an animal model of acute arthritis.

OBJECTIVE: To assess the effects of heat and cold on quantifiable pain behaviors in an animal model of arthritis that minimizes the motivational-affective component of pain. DESIGN: The effects of superficial heat (40 degrees C) and cold (4 degrees C) on pain behaviors in rats with knee joint inflammation were tested before and after induction of inflammation and after treatment with heat or cold. SUBJECTS: Joint inflammation was induced in male Sprague-Dawley rats by intra-articular injection of the knee joint with 3% kaolin and 3% carrageenan. MAIN OUTCOME MEASURES: Withdrawal latency to heat applied to the paw (PWL) assessed secondary hyperalgesia; spontaneous pain behaviors assessed degree of weight bearing/ guarding; and joint circumference assessed joint swelling. RESULTS: Cold treatment of the inflamed knee joint significantly reversed the PWL immediately after treatment (p = .003) without affecting spontaneous pain behaviors orjoint circumference. In contrast, heat treatment produced a small but significant decrease in spontaneous pain behaviors (p = .03) without affecting PWL or joint circumference. CONCLUSION: Acute arthritic pain can be treated with either superficial heat for reducing guarding or with cold for reducing pain or hyperalgesia outside the injury site.

Unusual zwitterion of D,L-beta-carboxyaspartic acid: pKa and X-ray crystallographic measurements.

An investigation of the acidic properties and molecular structure of the new natural amino acid beta-carboxyaspartic acid (Asa) is described. The four pKas of Asa were determined by using a microtitration technique and are 0.8 +/- 0.2, 2.5 +/- 0.1, 4.7 +/- 0.1, and 10.9 +/- 0.1. The three pKas of 5-hydantoinmalonic acid were similarly measured and are 1.85 +/- 0.05, 4.63 +/- 0.05, and 10.20 +/- 0.05. 5-Hydantoinmalonic acid was used as a model for Asa with peptide bonds. Asa crystallizes in the monoclinic space group Cc with four molecules per unit cell of dimensions a = 13.112 (3) A, b = 8.207 (3) A, and c = 7.292 (2) A and beta = 108.03 (2) degrees. The structure was solved by direct methods and refined to final values for the discrepancy indices of R = 0.029 and wR = 0.036. The two molecules of Asa are linked by a very strong hydrogen bond between one of the beta-carboxyls and the alpha-carboxyl group of an adjacent molecule. Analysis of the pKa data indicates that the predominate zwitterion in solution results from ionization of a beta-carboxyl group. The X-ray data indicate that in the solid state the negative charge of the zwitterion is distributed approximately equally between one of the beta-carboxyls and the alpha-carboxyl group.