Effect of methylene blue on resuscitation after haemorrhagic shock.

OBJECTIVE: To compare prehospital hypotensive resuscitation with volume resuscitation, and find out whether reagents that inhibit free-oxygen radical formation, such as methylene blue, can improve resuscitation and survival. DESIGN: Randomised controlled trial. SETTING: Animal laboratory, Israel. ANIMALS: 48 adult male Wistar rats. INTERVENTIONS: After 30 minutes of controlled haemorrhage, rats were subjected to 60 minutes of uncontrolled haemorrhage with simultaneous resuscitation. Hartmann's solution alone, or with blood or with a bolus of methylene blue were infused to maintain the mean arterial pressure (MAP) at 80 or 40 mm Hg. Then haemorrhage was stopped and Hartmann's solution plus whole blood were infused to obtain a MAP that was within normal limits. MAIN OUTCOME MEASURES: Volumes of shed blood and resuscitation fluids, MAP, packed cell volume, blood pH and base deficit, and survival. RESULTS: During uncontrolled haemorrhage. a MAP of 80 mm Hg could not be reached in animals resuscitated with Hartmann's solution alone, and all died. All the rats given Hartmann's solution with a bolus of methylene blue or with whole blood achieved a higher MAP. MAP of 40 mm Hg was attained in all animals regardless of the resuscitation fluid. Only 15 of 24 animals resuscitated to a MAP of 80 mm Hg survived, compared with 22 survivors of the 24 rats resuscitated to a MAP of 40 mm Hg (p <0.04). Methylene blue or whole blood drastically reduced the volumes of shed blood and of fluids required, and moderated the reduction in packed cell volume, particularly during hypotensive resuscitation. CONCLUSION: Hypotensive protocols should be used to improve survival. Methylene blue given with the electrolyte solutions could negate their detrimental effects during resuscitation.

Reduction in formation of peritoneal adhesions by methylene blue in rats: a dose response study.

OBJECTIVE: To find out if the ability of methylene blue given intraperitoneally to reduce surgically-induced adhesions in rats is concentration dependent. DESIGN: Random, controlled prospective study. SETTING: Teaching hospital, Israel. ANIMALS: Seventy female Wistar rats. INTERVENTIONS: Intraperitoneal adhesions were generated in rats by scraping the anterior wall of the uterine horn. They were then given either saline or serially diluted methylene blue intraperitoneally. Additional rats received identical treatments, but without the serosal damage. OUTCOME MEASURES: Graded formation of adhesions, two weeks later. RESULTS: In the rats treated with methylene blue 1%, adhesion formation was similar to that in sham operated rats and was significantly lower (p < 0.001) than in all other groups. CONCLUSION: Methylene blue 1%, and to lesser degree 0.5%, had the best anti-adhesion potential. Lower methylene blue concentrations were only partially effective, and much high concentrations may cause adverse effects.

Comparative study of splenic wound healing in young and adult rats.

BACKGROUND: Nonoperative management (NOM) of splenic injuries is a common practice in stable trauma patients. Nevertheless, age-related differences in the success rate of NOM have prompted inclusion of age among the criteria of patient selection. Elucidation of the cellular mechanism of splenic wound healing in the young versus that of adults may explain why age can be related to the success of NOM in splenic injuries. METHODS: A laceration was made in the splenic antihilar surface of 40 young and 40 adult male rats. Postoperatively, at specified intervals extending until day 21, spleens were removed, fixed, and examined by routine histopathology. In addition, sections were stained histochemically for collagen fibers and immunohistochemically for myofibroblast histomorphometry. RESULTS: The intense local hemorrhage was resorbed within 48 hours in the young rats, and within 7 days in the adults. Disappearance of germinal centers and other splenic alterations started on the first day in both groups, but regeneration of splenic parenchyma was accomplished after 14 days in the young, whereas in the adults, on day 21 it was still incomplete. Maximal myofibroblast accumulation at the laceration site was seen after two days in the young, whereas in adults only on day 4 (p < 0.0001). Collagen scars were not present in either group. Thickening of the damaged capsule, composed of collagen fibers with yellowish-green polarization colors, was observed only in adult rats. CONCLUSION: Splenic wounds heal by regeneration and not by collagen scarring. In the young, myofibroblasts accumulate in the site of injury faster than in adults. These cells may enhance contraction and increase the rate of wound healing until parenchymatic regeneration is completed. Our results may indirectly explain the higher success rate of NOM of splenic injury in young patients.

[Kapoera--popular dance or martial art?].

Kapoera, a combination of acrobatics and coordinated athletic movement, is believed to have been introduced to South America during the 19th century by transported African slaves. The dance does not involve intentional physical contact, but during 6 months, 3 patients were admitted here for injuries induced by the forceful movements of this dance. 2 underwent exploratory laparotomy that revealed bowel perforations and 1 suffered a comminuted nasal bone fracture. Medical personnel should be familiar with the potential hazards of this dance and martial art.

The specificity and kinetic properties of trypsin ethylated at the binding site.

Treatment of trypsin with triethyloxonium tetrafluoroborate at pH 8, 25 degrees C, results in abolition of binding to the enzyme of specific cationic substrates and inhibitors. The binding constant of soybean trypsin inhibitor to ethylated trypsin is 10000-fold smaller than to intact trypsin. However, the intrinsic ability of trypsin to recognize and react with nonspecific neutral substrates and inhibitors is not lost, and in several cases even considerably enhanced. Thus ethylated trypsin (Tret) resembles chymotrypsin in its behavior. Trypsin-like enzymes are also affected in a similar manner.