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Biomedical subjects

J B Powell

Publications and source records attributed to J B Powell.

17 recordsLinked to original sources
PubMed1990

Glutathione protects cardiac and skeletal muscle from cyclophosphamide-induced toxicity.

Administration of cyclophosphamide at a dose which is lethal to 10% of control athymic nude mice resulted in sudden death within 3 h in all mice that had been pretreated with the glutathione synthesis inhibitor L-buthionine-SR-sulfoximine. In Fischer 344 rats pretreated with L-buthionine-SR-sulfoximine, the cyclophosphamide dose producing 100% acute toxicity was lowered from 500-150 mg/kg; cardiac monitoring revealed ventricular fibrillation to be the cause of death. These and additional studies reported demonstrate that cytoplasmic glutathione is an important protectant against the cardiac and skeletal muscle toxicity of cyclophosphamide and indicate that such toxicity may be substantially increased by glutathione depletion. Since diet and many drugs (including cyclophosphamide itself) are known to affect glutathione levels, the present studies suggest that cardiac and skeletal muscle glutathione content is likely to be a clinically significant determinant of the frequency and severity of the adverse drug interactions and systemic toxicity sometimes observed during cyclophosphamide therapy.

Animals↗
PubMed1988

Chronic fatigue in primary care. Prevalence, patient characteristics, and outcome.

Although fatigue is one of the most common complaints in ambulatory care, research has been minimal. Of the 1159 consecutive patients surveyed in two adult primary-care clinics, 276 (24%) indicated that fatigue was a major problem. Fatigue was more prevalent in women than in men (28% vs 19%). Extensive clinical, laboratory, psychometric, and functional data were gathered for 102 fatigued patients and 26 controls. Laboratory testing was not useful in detecting unsuspected medical conditions or in determining the cause of fatigue. Depression or somatic anxiety or both were suggested by screening psychometric instruments in 82 fatigued patients (80%) compared with three controls (12%). Global dysfunction was marked, as reported by patients on the Sickness Impact Profile. The mean score on the Sickness Impact Profile of 11.3 for fatigued patients is similar to that reported for patients with major medical illnesses. After one year of follow-up, only 29 fatigued patients (28%) had improved. The high prevalence, persistence, and functional consequences of fatigue mandate a search for effective therapy.

Adult↗
PubMed1983

Nasolacriminal dysfunction.

This investigation describes the normal function of the lacrimal drainage system of the eye. The intent of the presentation is to illustrate by clinical examples and pertinent literature, those alterations of normal function occurring from obstruction, trauma, or neoplasm. Sixty-nine patients with lacrimal dysfunction are included; 19 are offered in detail to illustrate principles of surgical management. It is not within the scope of this discussion to examine any condition which may cause primary hyperlacrimation or hypolacrimation, but to discuss: 1. the role of trauma as a cause of lacrimal drainage dysfunction. 2. the role of surgery in the prevention of lacrimal dysfunction, and 3. the role of surgery in the restoration of function. Among 18 patients with non-traumatic obstruction treated by silicone stenting, previous multiple dilatations treatment was associated with a higher rate of failure than in those patients not previously treated by multiple dilatations. Forty percent of 96 patients with facial fractures of the medial orbit had obstructive nasolacrimal symptoms; 79% of the 96 patients' symptoms cleared spontaneously; 15% required treatment. No incidence of significant iatrogenic trauma (requiring surgical treatment) was found in reviewing 1292 cases of rhinoplasty, rhinoseptoplasty, blepharoplasty, or sinus surgery. Normal function and physiology are reviewed. From the experiences of 69 patients emerge clinically proven methods of surgical management of lacrimal system obstruction. These methods are defined and then compared and contrasted to traditional methods and concepts. When there is disagreement or no consensus, alternate theories are discussed in attempting to explain those clinical conditions which seem to defy accepted principles. This presentation includes cases which have been managed by surgeons other than the author and who have been trained in fields other than otolaryngology. The cases offered in detail have been managed by the author.

Adult↗
PubMed1983

Adenoma of the middle ear.

Benign adenoma of the middle ear emerged as a distinct entity following a review of 20 cases as reported from the Armed Forces Institute of Pathology in 1976. We report 4 additional cases and note that the pathologic diagnosis is not so clear cut. Benign primary adenoma may be confused with adenocarcinoma, ceruminoma, and glomus tumor. The otologic surgeon must take a hard look at the clinical signs and symptoms to determine if they are compatible with the diagnosis of primary middle ear adenoma. While middle ear adenoma has recently been implicated as a cause of facial paralysis (including a case herein), bone destruction should never be found in concert with this neoplasm.

Adenocarcinoma↗
PubMedDate not supplied

Quantitation of the nitrosamine 2-ethylhexyl-4-(N-methyl-N-nitrosoamino) benzoate (NPABAO) in sunscreen products.

We have devised a method to quantitate the nitrosamine, 2-ethylhexyl-4-(N-methyl-N-nitrosoamino) benzoate (NPABAO), in commercial products containing the sunscreen ingredient, Padimate O. The method involves a minimum of cleanup steps to afford a nonaqueous extract from product emulsions suitable for analysis by a liquid chromatograph interfaced to a thermal energy analyzer (LC/TEA). The method is applicable to lotions, creams, and gels. Oils are normally soluble in the mobile phase and can be analyzed directly on the LC/TEA without additional cleanup procedures. The method has a minimum detectable limit of about 30 ppb and yields greater than 80% recovery. It is highly reproducible and generates no NPABAO artifactually prior to quantitation on the LC/TEA. Application of the method to 22 different commercial product formulas disclosed that the level of NPABAO in each of the products is below 250 ppb, with 18 of the products containing less than 100 ppb. Of interest was the observation that musk ketone, a common fragrance constituent, produces a false-positive TEA response that can interfere with accurate analysis of NPABAO content in typical commercial products.

Aniline Compounds↗