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)

Blunt rupture of the heart in a child.

The spectrum of blunt cardiac trauma ranges from injuries with no actual cellular damage (myocardial concussion) to cardiac chamber rupture. Although blunt injuries to the heart are common and potentially lethal, rupture of a cardiac chamber is rare. This injury should be suspected in any patient who presents with cardiac tamponade after blunt trauma. A child who sustained blunt rupture of the right atrium is presented, and the pathophysiology, diagnosis, and treatment of these injuries are discussed.

Wilms' tumor in horseshoe kidney: presentation due to ureteropelvic junction obstruction.

Children with horseshoe kidney usually develop urinary tract symptoms and often require operative correction of the anomaly. The incidence of Wilms' tumor in horseshoe kidney is higher than that for the general population. We present the case of a child whose Wilms' tumor was diagnosed early because of ureteropelvic junction obstruction secondary to a horseshoe kidney. A high index of suspicion should be maintained for Wilms' tumor in any child with a horseshoe kidney.

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 an arginine-free enteral diet on wound healing and immune function in the postsurgical rat.

Critically ill patients have increased rates of sepsis partly due to a down-regulated immune system. Nutrients may modulate the immune system. The following studies were performed to determine whether arginine is one of these "essential" nutrients for the immune system. Thirty-two male Sprague-Dawley rats (weighing 175 g) were divided into two groups that were pair-fed with either an elemental, arginine-supplemented enteral diet, or the same diet with arginine removed and replaced with glycine. Both diets were isocaloric, isoosmolar, and isonitrogenous. After 6 days on the diet, animals underwent testing. There were no significant differences between the arginine-supplemented and the arginine-free diet groups in blood glucose or hematocrit. The arginine-supplemented animals had higher serum albumin (4.1 +/- 0.1 mg/dL v 3.6 +/- 0.1 mg/dL; P = .035) and serum protein levels (5.2 +/- 0.1 mg/dL v 4.3 +/- 0.1 mg/dL; P = .041); and had higher thymus gland (0.53 +/- 0.03 g v 0.44 +/- 0.02 g; P less than .0001) and spleen weights (0.66 +/- 0.01 g v 0.57 +/- 0.01 g; P less than .01). Daily total urinary nitrogen excretion, nitrogen balance, and weight gain showed a tendency for the arginine-supplemented animals to retain more of their nitrogen calories. There was no difference in the amount of hydroxyproline (OHP) found in the wound cylinders of either group (both 25.6 micrograms OHP/cm polytetrafluoroethylene) but the arginine-supplemented group's wounds had greater wound bursting strengths (429 +/- 3 g/cm v 350 +/- 7 g/cm; P = .044).(ABSTRACT TRUNCATED AT 250 WORDS)

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)

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.

Pheochromocytoma and acute myocardial infarction.

When a pheochromocytoma is manifested as an acute myocardial illness, diagnosis may be difficult to make. If the tumor is suspected early enough, a workup can be done while the complications of the myocardial illness are being controlled (as in our case). The tumor can then be expeditiously removed before any further problems develop. The case presented here underscores the importance of maintaining a high index of suspicion for a pheochromocytoma in any patient who has an unexpected myocardial event.

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.