Biomedical subjects

S M Fiser

Publications and source records attributed to S M Fiser.

23 records · Page 2Linked to original sources

PubMed1998

Resource utilization in traumatic brain injury: the role of magnetic resonance imaging.

Cerebral CT scanning is routine in the acute evaluation of traumatic brain injury (TBI) patients. MRI has been reported to identify cerebral lesions better than CT scan. The purpose of this study was to determine whether MRI influenced the acute diagnosis and management of TBI patients. A retrospective medical records review was performed on all TBI patients undergoing cerebral CT scan and MRI admitted to a regional trauma center during a 2-year period. Patient data collected included demography, extent of TBI, CT scan and MRI use, and therapeutic interventions. Forty TBI patients (initial Glascow Coma Scale, 8.8+/-0.7) underwent 79 CT scans and 40 MRIs. Time to initial CT scan was 6.3+/-4.3 hours and time to MRI was 2.9+/-3.1 days. Nine patients (22.5%) had injuries on CT scan but not on MRI, most commonly skull fractures or small subarachnoid hemorrhages. Twenty-four patients (60%) had injuries on MRI but not on CT scan, most commonly corpus callosum shear injuries. There were two cases of child abuse and both had injuries of varying ages identified by MRI, but not CT. All injuries requiring a therapeutic intervention or change in management were identified by CT scan. Magnetic resonance angiography identified one patient with a traumatic internal carotid artery thrombosis. The performance of MRI resulted in additional charges of $75,640 or $3,152/patient identified with a new lesion. Although MRI identifies lesions not evident on CT scan, MRI does not alter management plans and is of limited value in the acute management of TBI. MRI may be of medicolegal benefit in cases of child abuse.

Adult↗

PubMed1997

Excess putrescine accumulation inhibits the formation of modified eukaryotic initiation factor 5A (eIF-5A) and induces apoptosis.

DH23A cells, an alpha-difluoromethylornithine-resistant variant of the parental hepatoma tissue culture cells, express high levels of stable ornithine decarboxylase. Aberrantly high expression of ornithine decarboxylase results in a large accumulation of endogenous putrescine and increased apoptosis in DH23A cells when alpha-difluoromethylornithine is removed from the culture. Treatment of DH23A cells with exogenous putrescine in the presence of alpha-difluoromethylornithine mimics the effect of drug removal, suggesting that putrescine is a causative agent or trigger of apoptosis. Accumulation of excess intracellular putrescine inhibits the formation of hypusine in vivo, a reaction that proceeds by the transfer of the butylamine moiety of spermidine to a lysine residue in eukaryotic initiation factor 5A (eIF-5A). Treatment of DH23A cells with diaminoheptane, a competitive inhibitor of the post-translational modification of eIF-5A, causes both the suppression of eIF-5A modification in vivo and induction of apoptosis. These data support the hypothesis that rapid degradation of ornithine decarboxylase is a protective mechanism to avoid cell toxicity from putrescine accumulation. Further, these data suggest that suppression of modified eIF-5A formation is one mechanism by which cells may be induced to undergo apoptosis.

Animals↗

PubMed1997

Lower extremity iatrogenic nerve injury due to compression during intraabdominal surgery.

BACKGROUND: latrogenic nerve injury due to poor positioning and external compression is a common surgical complication. However, sciatic neuropathy from external compression and femoral nerve injury after self-retaining retraction are less-published complications. METHODS: Surgical Morbidity and Mortality Reports from 1986 through 1995 were reviewed to identify femoral and sciatic neuropathies following intraabdominal vascular and general surgeries. RESULTS: Two sciatic and 5 femoral neuropathies were reported, an incidence of approximately 0.17% of abdominal cases. Sciatic injuries were attributed to external compression, whereas femoral neuropathies were due to compression by self-retaining retraction. The 3 female and 4 male patients had a mean age of 53.4 years, and no patient had a prior history of peripheral neuropathy. Mean operating time for sciatic injuries was 8.2 hours, versus 4.3 hours for femoral neuropathies. Both patients with sciatic neuropathy had complete resolution of symptoms, compared with 1 femoral neuropathy patient. Two femoral neuropathies were permanent, 1 had partial resolution and 1 had improvement at 4 months but was lost to follow-up. CONCLUSIONS: Sciatic and femoral compression neuropathies are rare but serious complications of abdominal surgery. When retracting in the deep pelvis, consideration should be given to using small, well-padded retractor blades and repositioning these regularly. Prevention of sciatic nerve compression requires careful padding of the table surface, especially for longer cases.

Abdomen↗

PubMed1994

Consequences of aberrant ornithine decarboxylase regulation in rat hepatoma cells.

DH23A cells, an alpha-difluoromethylornithine (DFMO)-resistant variant of rat hepatoma tissue culture cells (HTC), contain high levels of very stable ornithine decarboxylase (ODC). In the absence of DFMO, the high ODC activity results in a large accumulation of endogenous putrescine. Concomitant with the putrescine increase is a period of cytostasis and a subsequent loss of viable cells. In contrast, HTC cells with a moderate polyamine content can be maintained in exponential growth. This suggests that a moderate polyamine concentration is necessary for both optimal cell growth and survival. The cytotoxicity observed in the DH23A cells is apparently not due to byproducts of polyamine oxidation or alterations in steady state intracellular pH or free [Ca2+]. It is possible to mimic the effects of high levels of stable ODC by treatment of cells with exogenous putrescine in the presence of DFMO. This suggests that overaccumulation of putrescine is the causative agent in the observed cytotoxicity, although the mechanism is unclear. These data support the hypothesis that downregulation of ODC may be necessary to prevent accumulation of cytotoxic concentrations of the polyamines.

Amine Oxidase (Copper-Containing)↗

PubMedDate not supplied

Carotid arteriography impacts carotid stenosis management.

Recent literature advocates carotid endarterectomy on duplex alone. The authors hypothesized that carotid angiography adds information that alters clinical management in a substantial number of patients compared to the use of carotid duplex examination alone. The records of 182 consecutive patients who underwent carotid artery duplex and subsequent carotid/cerebral angiography for suspected carotid artery stenosis between January 1998 and April 1999 were reviewed retrospectively. Carotid artery duplex examinations were stratified based on stenosis: < or =39%, 40% to 59%, 60% to 79% (moderate), 80% to 99% (severe), 100%. Carotid stenosis on angiograms was determined by NASCET criteria. New information found at angiography included vertebral, subclavian, or arch atherosclerosis, intracranial pathosis, or a change in duplex stenosis category to a degree of stenosis not requiring surgery. Clinical importance was attributed to angiograms that altered the patients' management plan. Angiography provided additional information in 53% (97/182) of patients. Vertebral disease was found in 25.1%, subclavian disease in 16.4%, intracranial disease in 15.3%, aortic arch disease in 3.3%. Patient treatment was altered in 30% (55/182). Angiographic findings downgraded the stenosis to medical therapy in 20.9% (38/182). The surgical plan was influenced in 5.5% (10/182). Nine intracranial aneurysms were discovered. Carotid angiography was essential for vascular bypass surgery planning in 3.3% (6/182). Angioplasty was performed in 2.2% (4/182). The accurate determination of stenosis is critical in determining optimal treatment of patients with carotid artery stenosis. Routine carotid angiography remains valuable in the clinical treatment of these patients.

Aged↗