A simple method for the rapid generation of recombinant adenovirus vectors

Recombinant adenoviruses are useful vectors for basic research. When the vectors are used for delineating protein function, several viruses, each containing a mutated version of the transgene are compared at the same time. However, methods to generate multiple vectors simultaneously within a short time period are cumbersome. In this report, we show that a novel backbone plasmid, when cotransfected with routinely used shuttle vectors into HEK293 cells allowed for production of recombinant viruses in an average of 14 days. The recombinant viruses had no detectable wild-type virus contamination by A549 plaque assay and only three to 300 E1a copies per 109 adenovirus genomes by a sensitive PCR-based assay. Further culturing or serial amplification did not result in wild-type revertants nor did cultures show increased levels of E1a copy number by quantitative PCR. Thus, recombinant adenovirus vectors can be produced very simply, rapidly and with little to no contaminating wild-type particles. This system should facilitate the generation of multiple genetic variants by eliminating the need for time-consuming plaque purification and the need to manipulate and screen very large plasmids. We call this the RAPAd.I system.     

Mild hypoglycemia and impairment of brain stem and cortical evoked potentials in healthy subjects

To evaluate the impact of mild hypoglycemia on CNS function in healthy adults, we measured brain stem auditory evoked potentials and P300 potentials (elicited by cognitive processing of auditory stimuli) during hypoglycemic or euglycemic insulin clamps (80 mU.m-2.min-1). In the hypoglycemic clamp study (n = 8), plasma glucose was allowed to fall from 4.6 to 3 mM in hourly approximately 0.5-mM steps and subsequently returned to euglycemic baseline levels. In the euglycemic clamp study (n = 8), plasma glucose was maintained at baseline levels throughout. Neither brain stem nor P300 responses changed during the euglycemic control study; symptoms and counterregulatory hormones were also unaffected. During the hypoglycemia study, epinephrine and growth hormone rose once plasma glucose reached 3.4 +/- 0.1 mM. Brain stem and P300 potentials remained unchanged until the 3-mM glucose step, when neurophysiological changes suddenly developed in conjunction with reported symptoms. At this glucose level, the wave V component of the brain stem potential was selectively altered in 7 of 8 subjects. Furthermore, P300 latency significantly increased, and amplitude diminished. Changes in both brain stem and cortical (P300) responses reversed when euglycemia was restored. We conclude that modest reductions in plasma glucose (to 3 mM) produce marked alterations in both brain stem and cortical responses to auditory stimuli. These changes in neural function appear at the same time as symptoms and follow rather than precede the rise in counterregulatory hormones during hypoglycemia. Our data suggest that the adverse effects of mild hypoglycemia on brain function are not limited to higher centers but also involve the brain stem.     

Xanthogranuloma of the Anterior Skull Base: A Case Report

A case of a xanthogranuloma arising in the anterior skull base involving the bone of the left orbital roof, the dura mater, and the periorbit is presented. The lesion was completely removed by a supraorbital “eyebrow” skin incision using frameless stereotactic image guidance. A reconstruction of the orbital roof was performed using a titanium mesh graft. The neuropathological investigation revealed all the characteristics of a xanthogranuloma. Intracranially, xanthogranulomas appear as rare tumors of the dura or choroid plexus, usually arising in association with histocytosis X or familial hyperlipoproteinemia. One case not associated with these diseases is discussed.     

Intellectual and attitudinal characteristics of medical students selecting family practice.

Family practice residents were compared with residents in internal medicine, surgery, obstetrics-gynecology, and pediatrics in terms of cognitive and non-cognitive characteristics. Family practice residents were in most instances significantly different from the other four groups. On non-cognitive measures they scored higher on affiliation need and lower on aggression and materialism. Their scores on several cognitive measures were among the highest of the five groups. These results were contrary to others from earlier studies. However, if the trend reported here is confirmed on other samples, it is the more intellectually gifted and idealistic physician who is currently being attracted to the practice of family medicine.     

Epidural metastasis of a glioblastoma after stereotactic biopsy: case report.

Tumor seeding along the biopsy tract is a rare complication in stereotactic biopsy. We present the unique case of a 42-year-old male with epidural tumor seeding along the needle tract after computer tomography-guided stereotactic biopsy of a glioblastoma in the right basal ganglia. Three months after the biopsy and one week following fractionated radiation therapy, the patient died of brain edema and cardiac dilatation. Besides further tumor growth at the primary site, autopsy revealed a right frontal epidural, nodular metastatic tumor at the site of dura incision of the stereotactic biopsy. Histological examination showed a glioblastoma that spread epidurally along the needle tract. This is the first report of an epidural intracranial implantation metastasis of a glioblastoma after stereotactic biopsy.