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Biomedical subjects

W E Allen

Publications and source records attributed to W E Allen.

At least 145 records · Page 8Linked to original sources

Multiple myeloma mimicking pituitary adenoma.

A case of multiple myeloma which presented as a solitary intrasellar tumor is reported. The initial radiographic and light microscopic findings were interpreted as being consistent with pituitary adenoma. Subsequently, when systemic disease developed and a bone marrow biopsy demonstrated multiple myeloma, the histopathologic diagnosis of the sellar lesion was established retrospectively.

Adenoma↗

Effect of mannitol on the traumatized spinal cord. Microangiography, blood flow patterns, and electrophysiology.

The effects of mannitol on the spinal cord blood flow patterns in experimental traumatic paraplegia were correlated with microangiographic and electrophysiologic studies. At 1 hour following a therapeutic dose of mannitol (3 g/kg), an improved fluorescent intramedullary vascular pattern was detected among the mannitol-treated animals relative to those that were not treated. Within 4 hours, perfusion of many areas of the lateral white matter of the spinal cord often approximated normal in the mannitol-treated group. This pattern of perfusion was in striking contrast to that seen in the spinal cord of untreated animals, which displayed an almost total lack of fluorescing vessels at this later time. These findings correlated with an increased vascular caliber as revealed by microangiography and were postulated to be the result of a decrease in vasospasm and an expanded intramedullary blood volume following the administration of mannitol. Although mannitol therapy did not reverse the loss of the cortical evoked response observed during the 4-hour interval studied, the observation of improved blood flow patterns in the white matter is encouraging and warrants further study.

Angiography↗

Evaluation of the effects of fragmented steam exposure cycles on the survival of bacterial spores.

The purpose of this study was to examine the population and resistance characteristics of bacterial spores which have been exposed to an abbreviated steam sterilization cycle. The philosophy of many pharmaceutical manufacturers is to require a second complete terminal sterilization cycle in the event of an unplanned interruption during the terminal sterilization of a production batch. The impact of abbreviated steam sterilization cycles was examined for their effect on the survivability and resistance of bacterial spores following an inadequate sterilization cycle. Steam sterilization cycles of two minutes and four minutes were performed on separate groups of Biological Indicator spore strips. These groups were then held at room temperature and re-exposed to a range of sterilization conditions after 24, 48, and 72 hours, i.e., start cycle, abort, hold, start cycle, abort. Spore survivor curves were calculated and resistance estimations were determined. The results of the study indicated that the log level of the surviving spores remained fairly constant, but variability within groups increased as sterilization time increased. The resistance of these surviving spores, as measured by D value, also remained relatively constant throughout the holding period. Abbreviated cycles were similarly conducted on ampules containing a spore suspension, and the spore populations and moist heat resistances were determined over time. Contrary to the spore strip, the population of the subject ampules was less stable showing a gradual decline over the same observation period. The study also included a comparison of the surviving population of short and long fragmented cycles. The results of this study demonstrate that a second complete sterilization cycle is unnecessary to assure the absence of living matter in the sterilized units.

Spores, Bacterial↗