Jason G. Nirgiotis

Blunt trauma to the heart: The pathophysiology of injury

Blunt injuries to the heart are common and potentially lethal. These injuries often go undetected while more obvious problems are treated. A cardiac injury should be suspected in any patient who sustains severe chest trauma. The spectrum of cardiac trauma ranges from injuries with no actual cellular damage (myocardial concussion) to cardiac chamber rupture. The pathophysiology, diagnosis, and treatment of these injuries are discussed.

Continuous EGF application impairs long-term collagen accumulation during wound healing in rats

Continuous topical application of epidermal growth factor (EGF) to granulation tissue has been demonstrated to increase the rate of collagen accumulation in wounds. Studies from this laboratory have indicated that a single topical application of EGF leads to a short period of elevated wound collagen content, followed by a rapid breakdown of this newly acquired collagen. In light of recent clinical trials of EGF as an aid to wound healing, we studied the long-term effects of continuous EGF injection. Standard polytetrafluoroethylene (PTFE) wound cylinders were surgically placed in the dorsal midline of 40 male Sprague-Dawley rats. Rats received EGF daily for 14 days, at which time all injections ceased. Wound cylinders were removed for analysis from five test animals and five controls on study days 14, 21, 28, and 35. Wound collagen content in EGF-treated animals was significantly higher than in controls on the 14th day of the study (330% higher, P less than .002), but dropped to lower levels on each succeeding day (day 21: 97% of control, NS; day 28: 63% of control, NS; day 35: 72% of control, P less than .03). There was a significant increase in wound collagenase activity only on days 14 and 21, but not on days 28 and 35. We demonstrated that continuous application of EGF may artificially elevate wound collagen content, thereby leading to increased wound catabolism on cessation of treatment.

Low-fat, high-carbohydrate diets improve wound healing and increase protein levels in surgically stressed rats

The specific effects of omega 3 and omega 6 polyunsaturated fatty acids on wound healing, nutrition status, or immune function are controversial. Therefore, we investigated the effects of fatty acid supplementation on wound healing and nitrogen retention in a surgically stressed rat model. Male Sprague-Dawley rats (weighing 250 g) were placed into three isocaloric, isonitrogenous feeding groups (controls [standard Vivonex]; 30% safflower oil [omega 6]; or 30% fish oil [omega 3]) for 8 days prior to receiving subcutaneous vascular graft wound cylinders in their dorsal midline. Nitrogen balance was monitored daily. Wounds healed for 10 days, animals were then euthanized, serum was drawn, and wound cylinders were harvested for analyses. The low-fat, high-carbohydrate control group had higher serum albumin levels at 10 days than either fatty acid-supplemented group (3.5 +/- 0.4 g/dL v 2.9 +/- 0.3 g/dL and 2.7 +/- 0.2 g/dL, omega 3 and omega 6, respectively; both P less than .05) and had better nitrogen balance (8.6 +/- 0.8 mg N/d v -2.6 +/- 0.9 mg N/d and 0.8 +/- 1.2 mg N/d, omega 3 and omega 6, respectively; both P less than .05). They also had better healed wounds at 10 days (450 +/- 290 micrograms 5-hydroxyproline [OHP]/cm of wound cylinder v 150 +/- 40 micrograms OHP/cm and 145 +/- 90 micrograms OHP/cm, omega 3 and omega 6, respectively). Surgically stressed rats had higher protein levels, better nitrogen balance, and improved wound healing when fed a diet high in carbohydrates and low in fat.

The effects of age and various fat/carbohydrate caloric ratios on nitrogen retention and wound healing in rats

Recent reports have indicated a possible age-related component to the ability of various species to utilize either fat or carbohydrate as their preferential energy source. These studies have demonstrated that infant rats given a high-fat diet (50% fat, 35% carbohydrate, 15% protein) retain a significantly higher amount of nitrogen than do infant rats on a high-carbohydrate diet (82% carbohydrate, 3% fat, 15% protein). Conversely, adult rats maintain a higher positive nitrogen balance when given the high-carbohydrate diet. In light of these studies, and our interest in factors that contribute to wound healing in the surgical patient, we investigated the effects of low-, medium-, and high-fat enteral diets on wound healing and nitrogen balance in surgically stressed rats of various ages. Weanling (45 g) and young adult (175 g) male Sprague-Dawley rats (n = 16 per age group) were housed individually in metabolic cages. All animals had Impra vascular-graft wound cylinders placed subcutaneously in the dorsal midline and were placed in four dietary groups: high fat (50% kcal), medium fat (30% kcal), low fat (2.5% kcal), and chow (Purina Standard Laboratory Rodent Chow, 17% kcal as fat). All test diets were isonitrogenous (3.1 g nitrogen/1,000 kcal) and isocaloric for each age group. Animals in each age group were pair-fed (35 kcal/d, weanlings; 60 kcal/d, young adults) for 10 days and then euthanized. Wound cylinders were removed and analyzed for collagen content.(ABSTRACT TRUNCATED AT 250 WORDS)

Linoleic acid enhances mitogen response and survival of septic weanling rats

Immunologic responses to various dietary fats and concentrations remain controversial. The authors examined the effect of dietary omega-3 and omega-6 polyunsaturated fatty acids (PUFA) on the immune system of weanling rats. Male weanling Sprague-Dawley rats were fed special liquid diets based on a standard enteral formula: (I) control: 2.2% calories as safflower oil (linoleic acid), (II) omega-3: 2.2% calories as safflower oil and 30% calories as cod liver oil (linolenic acid), and (III) omega-6: 32.2% calories as safflower oil. Body weight and caloric intake were measured daily. Rats were fed special diets for 18 days, at which time they were subjected to either septic challenge with 2 x 10(3) colony forming units of Streptococcus pneumoniae (eight rats per diet group) or killed and a splenocyte mitogen assay performed (four rats per diet group). Supplementation with omega-6 resulted in prolonged survival after bacterial challenge (control, 30.5 +/- 0.5 hours; omega-3, 31.6 +/- 0.5; not significant; omega-6, 39.8 +/- 5.0; P < .05). A significant difference in mitogenic stimulation was seen with omega-3 and omega-6 in response to PHA (control, 10,856 +/- 3,342; omega-3, 14,605 +/- 3,042; P < .05; omega-6, 35,737 +/- 7,596; P < .05) and with omega-6 only in response to LPS (control, 3,543 +/- 1,083; omega-3, 8,777 +/- 1,269; omega-6, 10,101 +/- 3,008). Previous studies have suggested that diets high in omega-6 PUFA are immunosuppressive because of an increase in the production of the dienoic prostaglandins.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of Complex Duodenal Atresia with Duodenojejunostomy

The most common form of duodenal atresia presents as an obstruction in the second portion of the duodenum distal to the ampulla of Vater and is usually treated with duodenoduodenostomy. On occasion, h