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Biomedical subjects

T Levitt

Publications and source records attributed to T Levitt.

9 recordsLinked to original sources

Maxillary growth in patients with clefts following secondary alveolar bone grafting.

OBJECTIVE: This investigation evaluated the effects of secondary alveolar bone grafting on subsequent maxillary growth in cleft patients. DESIGN: This was a retrospective longitudinal cephalometric study. Nineteen patients who had received secondary alveolar bone grafts were matched to a control sample by sex, cleft, availability of longitudinal records, and presurgical cranial base dimensions and growth direction. All patients had at least two lateral cephalometric radiographs before surgery and two radiographs after surgery. SETTING: The records were obtained from the Longitudinal Growth Study of the Lancaster (Pennsylvania) Cleft Palate Clinic. INTERVENTIONS: All patients had received similar primary surgical procedures by the same surgeon, no orthopedics, and similar mixed-dentition orthodontics. Secondary alveolar bone grafting was the only surgical intervention different between the two groups. MAIN OUTCOME MEASURES: Six measures of maxillary sagittal and vertical growth were taken from 235 radiographs. Slopes of the regression lines for each growth dimension were compared between groups both pre- and postsurgically. RESULTS: There were no significant between-group differences in maxillary sagittal or vertical growth following the grafting procedure. Anterior maxillary vertical growth rates decreased in the grafted group when their pre- and postsurgical rates were compared. Several growth trends in the postsurgical period were found to be continuations of the rates documented presurgically and unrelated to the grafting procedure. CONCLUSIONS: When evaluated longitudinally, maxillary growth in patients having received secondary alveolar bone grafting did not differ from a group of matched controls.

Adolescent↗

Paraquat poisoning: significance of plasma-paraquat concentrations.

Plasma-paraquat concentrations were measured in 79 patients who had ingested liquid or granular weedkillers containing paraquat. At any given time after ingestion, the plasma-paraquat concentrations in the patients who died usually exceeded those in the survivors. It is suggested that measurement of plasma-paraquat concentrations is useful in assessing the severity and predicting the outcome of poisoning. Patients whose plasma concentrations do not exceed 2.0, 0.6, 0.3, 0.16, and 0.1 mg/l at 4, 6, 10, 16, and 24 h respectively are likely to survive.

Accidents↗

An heretical view of management science.

This article is introduced with the statement, "There is only one way to manage, and that is to keep it simple." The author is highly critical of the new managerial tools and decision-making modes developed by management scientists in business schools. He asserts that the use of these tools encourages a "corporations zeal for managerial perfection and threatens it with an excessive and paralyzing professionalism." Instead, Levitt suggests using "common sense" and "logical simplicity" in management by subdividing work into organizational units. This approach is viewed as an easy way to avoid being bogged down by "imagined facts" found in mathematical models. Levitt states that sense and moderation are the keys to success.

Humans↗

A rapid gas-liquid chromatographic estimation of nicotine in biological fluids.

A rapid gas-liquid chromatographic method for the estimation of nicotine in plasma is described. Nicotine is extracted from alkalinized plasma into diethyl ether. This is then concentrated by evaporation and, after an acid back extraction is re-extracted into n-heptane (nitrogen detector) or dichloromethane (flame ionization detector) before injection onto the gas chromatography. Thirty samples a day can be analysed by this method which enables concentrations of 0.1 ng ml- minus 1 nicotine to be measured. It is thus possible to measure nicotine in plasma and urine samples from non-smokers.

Chromatography, Gas↗