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Biomedical subjects

W J Peters

Publications and source records attributed to W J Peters.

70 records · Page 4Linked to original sources
PubMed1968

Itoic acid synthesis in Bacillus subtilis.

Under conditions of iron deficiency, strains of Bacillus subtilis produced 2,3-dihydroxybenzoic acid (DHB), 2,3-dihydroxybenzolyglycine (DHBG), or both of these compounds. DHB(G) production [production of DHB(G) refers to the production of DHB, or DHBG, or both] was proportional to the amount of iron present and occurred logarithmically, paralleling growth. Supplementation of media with more than 150 mug of iron per liter at zero-time inhibited DHB accumulation completely. In the presence of DHB, lower levels of iron inhibited DHB(G) production, so that the actual inhibitor of synthesis may involve the Fe(3+):[DHB(G)](3) complex. The strains producing DHBG also produced coproporphyrin III during iron-deficient growth, whereas a strain producing DHB did not produce coproporphyrin III under these conditions. Accumulation of DHB(G) was influenced by the levels of aromatic amino acids and anthranilic acid in the medium. In vivo experiments with strain B-1471 demonstrated that DHB was coupled to added glycine to form DHBG. Metabolism of DHB(G) was observed in two of the strains studied.

Bacillus subtilis↗
PubMedDate not supplied

Serum interleukin-2 receptor as a possible mediator of immunosuppression after burn injury.

Concentrations of the interleukin-2 receptor are significantly elevated in serum after burn injury. To examine the immunoregulatory potential of this molecule, suppressive activity of sera from patients with major burns (n = 16; 40% to 80% total body surface area) was assessed before and after immunoaffinity adsorption with interleukin-2. The preadsorption level of interleukin-2 receptor in the pooled serum after burn injury was 6250 U/ml. This serum demonstrated a strong suppressive activity, inhibiting expression of cellular interleukin-2 receptor and proliferative responses of normal human lymphocytes to alloantigen and exogenous interleukin-2 by 60% to 90%. Adsorption of pooled serum after burn injury with interleukin-2 lowered the level of interleukin-2 receptor to 1800 U/ml and reduced its immunosuppressive activity. The percentage of interleukin-2 receptor-bearing cells, and cell proliferative responses, increased by 50% to 70% compared with sham adsorbed pooled serum after burn injury. Thus serum interleukin-2 receptor after burn injury may represent a specific mediator for downregulation of interleukin-2-dependent responses.

Adult↗
PubMedDate not supplied

Heterotopic ossification: can early surgery be performed, with a positive bone scan?

It has been previously suggested that the surgical removal of areas of heterotopic ossification in patients with burns should be delayed until bone scans return to normal. The present study describes a patient who underwent surgical removal of heterotopic ossification from both elbows, 1 year after burn injury, with strongly positive bone scans, because of progressive ulnar nerve compression. Subsequently, 7 years after burn injury and 6 years after this surgery, the patient maintained an excellent range of motion in both elbows. At this time, his bone scans continue to be strongly positive. Didronel (Norwich Eaton, Norwich, N.Y.), a diphosphonate, may have played a role in this patient's recovery by decreasing bony deposition following surgery.

Adult↗
PubMedDate not supplied

Severe multiple mononeuropathy in patients with major thermal burns.

Multiple mononeuropathy after thermal burns covering greater than 40% total body surface area occurred in nine of 121 of our burn center admissions for an incidence of 7.4%. The number of nerves involved per patient ranged from three to seven, with the average being 4.9. Upper-extremity nerves were more commonly involved than were lower extremity nerves (33 versus 11). All patients had burns over the involved areas. The source was believed to be due to a multiple crush syndrome, in which multiple different neuropathic factors in each patient summate to cause a multiple mononeuropathy. The outcome with conservative treatment was variable, with lower-extremity nerve lesions having a very good outcome and upper-extremity lesions not having as good an outcome, particularly when the median nerve was affected.

Burns↗
PubMedDate not supplied

Thermal injury-associated neopterin production: regulation by interleukin-2.

Pteridin neopterin production by monocytes/macrophages has been linked to the biologic activity of immune activation- and/or infection-related cytokines. In patients with thermal injuries who succumb to infections, serum levels of both interleukin-2 (IL-2) and neopterin are significantly increased. However, the relationship between these two markers of immune activation remains unclear. This study examines the role of IL-2 in the biosynthesis of neopterin after major burn. Up to 4 weeks after burn, the levels of plasma neopterin and endotoxin were elevated in all patients studied (N = 9, 30% to > 90% total body surface area). Intact (unsupplemented) peripheral blood mononuclear cell (PBMC) cultures from patients with sepsis secreted high levels of neopterin spontaneously. The spontaneous release of neopterin was significantly decreased (p < 0.05) after supplementation with exogenous IL-2. The reverse was observed in peripheral blood mononuclear cell cultures from infection-free or control groups where relatively low neopterin secretion was markedly augmented in the presence of IL-2. The effect of IL-2 in patient cultures was unrelated to the activity of endogenous interferon gamma, because the production of this cytokine was profoundly reduced. However, IL-2-induced alterations in neopterin secretion paralleled those in the production of tumor necrosis factor alpha. This suggests that after thermal injury, biologic responses of neopterin-secreting peripheral blood mononuclear cells are directly or indirectly regulated by IL-2.

Adult↗
PubMedDate not supplied

Acute and chronic respiratory complications of toxic epidermal necrolysis.

Toxic epidermal necrolysis (TEN) is a rare disease resulting in bullous necrosis of the epidermis with partial-thickness loss of skin and mucous membranes. Previous reports of TEN have not focused on respiratory complications. During a 6-year period, 12 patients with biopsy-proven TEN were referred to a regional burn unit at the Wellesley Hospital, Toronto. Five patients required mechanical ventilatory support, and nine showed roentgenographic evidence of respiratory complications that had developed. Intensive therapy in a critical care burn unit resulted in a 75% survival rate. The four nonsurvivors had severe preexisting multisystem disease. Four survivors were observed prospectively, with 3 monthly pulmonary function testings performed. The four survivors tested, even if they did not require mechanical ventilatory support, showed evidence of respiratory involvement. Three patients demonstrated a persistent reduction in carbon monoxide diffusing capacity of up to 35% to 40% below normal. From our case series we suggest that TEN, although primarily a dermatologic condition, may result in life-threatening acute respiratory decompensation requiring ventilatory support and long-term pulmonary function abnormalities. Patients with TEN should be closely monitored for pulmonary complications.

Acute Disease↗
PubMedDate not supplied

Validation of a new formula for calculating the energy requirements of burn patients.

In a previous study, we analyzed the roles of the estimated basal energy expenditure (EBEE) calculated by the Harris-Benedict equation, caloric intake (CI), total burn surface area (TBSA), body temperature (Temp) and number of post-burn days (PBD) in order to estimate the resting energy expenditure (EE) of burn patients. By multiple regression analysis we found that the measured EE (MEE) is best approximated by the following formula: -4343 + (10.5 x %TBSA) + (0.23 x CI) + (0.84 x EBEE) + (114 x Temp (degree C)) - (4.5 x PBD), r = 0.82, p less than 0.001, (Toronto formula (TF)). To validate this, 10 patients with a mean TBSA of 49.1 +/- 5.5% had their resting MEE done by indirect calorimetry when fed either by the TF or by 2 x EBEE. The caloric intake when on 2 x EBEE was 3260 +/- 45 kcal/day which significantly exceeded the MEE (2765 +/- 101 kcal/day, p less than 0.001). The caloric intake when on the TF was 2542 +/- 52 kcal/day and matches the MEE which was 2537 +/- 86 kcal/day (NS). These results show that the TF matches the MEE very closely. With the addition of a factor of activity for the 24-hr EE, it can be used to accurately feed individual burn patients.

Adult↗