Impact of resident training on postoperative morbidity in patients undergoing single valve replacement. Department of Veterans Affairs Cooperative Study on Valvular Heart Disease

As one of the requirements of the Department of Veterans Affairs cooperative study on valvular heart disease, operative and postoperative data were prospectively collected in 964 patients undergoing single valve replacement. The procedure was performed either by a resident under the direct supervision of an attending surgeon (49.5%) or by an attending surgeon (50.5%). There was no difference in operative mortality between the two groups of surgeons when adjusted for patient-related and disease-related risk factors. The proportion of patients who had at least one postoperative complication was slightly but not significantly higher in the attending group (35.8% versus 30.4% for aortic valve replacement, 38% versus 28% for mitral valve replacement, and 36% versus 30% for all single valve replacement procedures). As the significance of each complication varies, we weighted each complication to the associated operative mortality to formulate the morbidity score. An expected complication rate for each group was derived from a multivariate logistic model, and the ratio of observed to expected morbidity was calculated to adjust observed morbidity according to the risk of patients. There was no difference in the observed/expected morbidity ratio between the two groups of surgeons. We conclude that currently used teaching techniques and philosophy to educate cardiac surgical residents, which allow them to take progressive responsibility for cardiac surgical procedures, are well justified, and patient care does not suffer when resident training is enhanced.     

Poisoning in children.

This study is a retrospective analysis of 670 cases of poisoning (including phenothiazine toxicity) admitted to this hospital in the past six years, accounting for 0.9% of all pediatric admissions. Nearly half (45%) of the cases were in the age group of 1-4 years. Medicines and chemicals were the commonest agents (53%), followed by pesticides (15%), kerosene (11.2%), plant poisons (9.4%), food poisoning (3.9%) and corrosives (1.9%). Accidental poisoning was the commonest (70%) followed by iatrogenic (29.6%) and suicidal (0.4%). Overall mortality was 1.8%. Stress is laid on judicious use of phenothiazines as antiemetics and replacing them with drugs of lesser toxicity.     

Acute and subacute toxicity study of inhaled methyl isocyanate in Charles Foster rats

Charles Foster male and female rats were exposed only once to 3.52 and 35.32 ppm doses of methyl isocyanate in separate experiments for 10 min each in an acute toxicity study, while in subacute toxicity experiments, they were exposed to 0.212, 0.265, and 0.349 ppm doses for 30 min daily, for 6 days, by inhalation. Clinical signs, mortality, body and organ weights, and changes in hematology and clinical pathology were routinely monitored to determine the principal organ sites damaged on exposure to the gas. During exposure, animals were observed to have congestion in eyes, lachrymation, nasal secretion and dyspnea, progressively increasing ataxia, and immobility. Uncoordinated movements were also observed, indicating effects on the nervous system. Upon microscopic examination of the viscera, pathological findings confined to bronchial tree, lung parenchyma, liver, and kidneys were observed.     

Optimal advertising for the Nerlove-Arrow Model under a replenishable budget

This paper considers an optimal control problem with two state variables for the dynamics of the Nerlove—Arrow advertising model. The optimal control is the rate of advertising expenditure required to maximize the present value of net profit streams over an infinite horizon subject to a replenishable budget. It is shown that an equilibrium level of advertising exists in all possible cases. It is interesting to note that this level happens to be non-singular in some cases. Also shown is the optimal transient approach to these equilibrium levels.     

Evidence for sequential utilization of fibronectin, vitronectin, and collagen during fibroblast-mediated collagen contraction

Contraction plays a major role in wound healing and is inevitably mediated through the mechanical interaction of fibroblast cytoskeleton and integrins with their extracellular matrix ligands. Cell-matrix attachment is critical for such events. In human dermal fibroblasts most such interactions are mediated by the beta1-type integrins. This study investigated the role played by key components in this system, notably fibronectin, vitronectin, and integrin subcomponents alpha2 and alpha5, which recognize collagen and fibronectin. Inhibition of adhesion through these ligands was studied either by antibody blocking or with fibronectin and/or vitronectin depletion. Functional effects of inhibition were monitored as force generation in collagen-glycosaminoglycan (IntegraTM) sponges, over 20 hours using a culture force monitor. Dose and time-course inhibition studies indicated that initial attachment and force generation (approx. 0-5 hours postseeding) was through fibronectin receptors and this was followed by vitronectin ligand and receptor utilization (4 hours onward). Utilization of the collagen integrin subcomponent alpha2 appeared to be increasingly important between 6 and 16 hours and dominant thereafter. Additionally, there was evidence for functional interdependence between the three ligand systems fibronectin, vitronectin, and collagen. We propose that there is a short cascade of sequential integrin-ligand interactions as cells attach to, extend through, and eventually contract their matrix. (WOUND REP REG 2002;10:-408)