Early pleural decortication for thoracic empyema in immunosuppressed patients

Patients with empyema and impaired immune response often remain in a toxic condition after tube thoracostomy because the infection is not localized and walled off satisfactorily. Consequently, the reported mortality rate is extremely high. Despite the expectation of a high mortality rate from thoracotomy and débridement in this category of critically ill patients, we were forced to perform pleural decortication in eight patients after lesser procedures had failed. They were immunodeficient because of (1) high-dose steroids (HDS) for sagittal sinus thrombosis, (2) HDS for systemic lupus erythematosus, (3) HDS for chronic myelogenous leukemia and myelofibrosis, (4) HDS for multiple myeloma, (5) hemolytic anemia with pulmonary infiltrates, (6) chemotherapy for Hodgkin's disease, (7) diabetes mellitus with Kimmelstiel-Wilson disease, and (8) diabetes mellitus with chronic glomerulonephritis. Six of the eight patients survived and were discharged with completely healed incisions 3 to 6 weeks after operation. This compares well with the survival rates reported by others. Although risky, the over-all survival rate may be better with thoracotomy and decortication than with prolonged tube drainage and open drainage in immunodeficient patients with empyema, and the period of morbidity is shortened considerably.     

Noninvasive hemodynamic assessment of the internal mammary artery in myocardial revascularization

Using transthoracic B-mode imaging and Doppler spectrum analysis it was found that the luminal diameter of the internal mammary artery and its hemodynamics were not significantly different among 15 preoperative patients (64 +/- 10 years) who underwent myocardial revascularization using the left internal mammary artery and young and older control groups (25 +/- 3 years and 61 +/- 9 years, respectively). These data indicate that older age does not significantly adversely influence the degree of intimal thickening and compliance in the internal mammary artery. Doppler spectrum analysis of the internal mammary artery in the patients who were operated on revealed conversion from a triphasic systolic waveform preoperatively to a unidirectional combined systolic/diastolic waveform at 1 week and 2 and 6 months postoperatively, characterized by a significant increase in the diastolic blood flow velocity and a significant decrease in the systolic blood flow velocity and the pulsatility and resistance indices. This study indicates that transthoracic B-mode imaging and Doppler spectrum analysis are promising noninvasive techniques in the preoperative assessment of internal mammary artery morphology and physiology. In addition, Doppler spectrum analysis can also be used in the long-term serial assessment of the internal mammary artery conduit after myocardial revascularization.     

Phenserine: a physostigmine derivative that is a long-acting inhibitor of cholinesterase and demonstrates a wide dose range for attenuating a scopolamine-induced learning impairment of rats in a 14-unit T-maze

Phenserine ((-)-N-phenylcarbamoyl eseroline), a carbamate analog of physostigmine (Phy), is a long-acting inhibitor of cholinesterase. We have assessed the potential clinical value of phenserine for cholinomimetic therapy of cognitive impairments associated with aging and Alzheimer's disease by evaluating its duration of in vivo activity against rat plasma acetylcholinesterase (AChE) and its effect on attenuating a scopolamine-induced impairment in learning performance of young rats in a shock-motivated 14-unit T-maze. Phenserine achieved maximum AChE inhibition of 73.5% at 5 min and maintained a high and relatively constant inhibition for more than 8 h. For analysis of effects on learning performance, 69, 3-month-old male Fischer-344 rats were pretrained in a straight runway to avoid electric footshock. On the following day, each animal received 15 trials in the 14-unit T-maze. Sixty minutes prior to the maze training, each rat received the first IP injection of either vehicle (Tween 80, ethanol and 0.9% NaCl) or phenserine at 1.5, 3.0, 4.0, 5.0, 7.5, or 10.0 mg/kg. Then 30 min prior to the training, each animal received a second IP injection of either 0.9% NaCl or scopolamine hydrochloride (0.75 mg/kg; SCOP). Compared to the vehicle-SCOP group, all but the 7.5 mg/kg dose of phenserine significantly ameliorated error performance, runtime, shock frequency and shock duration in SCOP-treated rats at the final block of three trials. Appearing to have a long effect and a wide therapeutic window, phenserine deserves further study as a cognitive enhancer.     

Foscarnet penetrates the blood-brain barrier: rationale for therapy of cytomegalovirus encephalitis

Hypertension is a major complication of rHuEPO therapy in hemodialysis (HD) patients. We have previously reported that patients receiving rHuEPO intravenously (i.v.) had higher mean arterial pressure (MAP) and plasma endothelin-1 (ET-1) levels than those in which the hormone was administered subcutaneously (s.c.). To test whether the increased serum ET-1 levels associated with i.v. rHuEPO administration are the result of a direct effect of the hormone on ET-1 release by the endothelial cells (EC), we examined the effects of rHuEPO in vitro. Bovine pulmonary artery endothelial cells (BPAEC) were exposed to doses of rHuEPO of 0.8; 1.6; 3.3 and 6.6 U/ml. A 24 hour-time course showed maximal ET-1 production at 12 hours for all the doses tested. A significant increase in cell proliferation over controls was observed at 24 hours, for all rHuEPO doses, and no correlation was found between ET-1 values and cell proliferation. Inhibition of protein synthesis by cycloheximide (10 micrograms/ml) abolished the stimulation of ET-1 release by rHuEPO. Thrombin (4 U/ml) and angiotensin II (10(-7) M), two potent stimulators of ET-1 release, had additive effects to those of rHuEPO. Specific thrombin and angiotensin II antagonists blocked these additive effects, reducing ET-1 release to the level of rHuEPO stimulation alone. In summary, rHuEPO stimulates vascular EC in culture to increase ET-1 release through an increase in synthesis and in a time dependent fashion. The routes of stimulation seem to differ from other known ET-1 secretogoges. Our data also confirm a significant mitogenic effect of rHuEPO on the endothelial cell.     

The effect of hole diameter on the torsional mechanical properties of the equine third metacarpal bone

The torsional monotonic structural material properties of equine metacarpi with or without, either a 5/16 inch or 3/8 inch diameter bicortical lateromedial middiaphyseal hole were assessed to determine the effect of a hole on metacarpal strength. Torsional stiffness was not significantly effected by the presence of a bicortical hole, whereas yield and failure angles, torques and energies of metacarpi with a hole were 51% to 97% of those of intact bones. Significant differences were not apparent for yield and failure mechanical properties between metacarpi with a 5/16 inch diameter hole and metacarpi with a 3/8 inch diameter hole; however, postyield mechanical properties were lower for metacarpi with a 3/8 inch hole. Whereas some metacarpi with a 5/16 inch hole were capable of plastic deformation before failure, metacarpi with a 3/8 inch diameter hole appeared to have sufficient stress concentration to propagate complete fracture on structural yield.     

Individual differences in freezing and cortisol in infant and mother rhesus monkeys

Freezing is an adaptive defensive behavior that is expressed in response to an imminent threat. In prior studies with rhesus monkeys, stable individual differences in animals' propensities to freeze have been demonstrated. To understand the factors associated with these individual differences, freezing behavior was examined in infant rhesus monkeys and their mothers, in conjunction with levels of the stress-related hormone cortisol. In both mothers and infants, basal cortisol levels were positively correlated with freezing duration. Additionally, the number of offspring a mother had was negatively correlated with her infant's cortisol level. These findings suggest a link between basal cortisol levels and an animal's propensity to freeze, as well as a mechanism by which maternal experience may affect infants' cortisol levels.