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Biomedical subjects

P A Rasmussen

Publications and source records attributed to P A Rasmussen.

14 recordsLinked to original sources
PubMed2000

Stent-assisted angioplasty of intracranial vertebrobasilar atherosclerosis: an initial experience.

OBJECT: Patients with intracranial vertebrobasilar artery (VBA) atherosclerotic occlusive disease have few therapeutic options. Unfortunately, VBA transient ischemic attacks (TIAs) herald a lethal or devastating event within 5 years in 25 to 30% of patients. The authors report their initial experience with eight patients in whom medically refractory TIAs secondary to intracranial posterior circulation atherosclerotic occlusive lesions were treated with stent-assisted angioplasty. METHODS: Eight patients (six men), ranging in age from 43 to 77 years, experienced signs and symptoms of VBA insufficiency despite combination therapy with warfarin and antiplatelet agents. Angiographic studies revealed severe distal vertebral (four patients), proximal basilar (one patient), or proximal and midbasilar stenoses (three patients). Aspirin and clopidogrel were administered for 3 days before primary angioplasty and stent placement, and this regimen was maintained by the patients on discharge. Patients underwent heparinization during the procedure and were given a bolus and 12-hour infusion of abciximab. A neurologist specializing in stroke evaluated all patients before and after the procedure. The VBAs in all patients were successfully revascularized with 7 to 28% residual stenosis. Six patients experienced no neurological complications. One patient died the evening of the procedure due to a massive subarachnoid hemorrhage. Two patients had groin hematomas, one developed congestive heart failure, and one had transient encephalopathy. All surviving patients are asymptomatic up to 8 months postoperatively. CONCLUSIONS: Although primary intracranial VBA angioplasty with stent insertion is technically feasible, complications associated with the procedure can be life threatening. As experience is gained with this procedure, it may be offered routinely as an alternative therapy to patients with medically refractory posterior circulation occlusive disease that may develop into catastrophic VBA insufficiency.

Abciximab↗
PubMed1996

Propofol inhibits epileptiform activity in rat hippocampal slices.

Propofol (2,6 di-isopropylphenol) is an intravenous general anesthetic used widely in neuroanesthesia, as a sedative in intensive care units, and has successfully aborted refractory status epilepticus. We investigated the effects of propofol on epileptiform activity in rat hippocampal slices. Interictal epileptiform activity was produced by bath applying one of the following: picrotoxin (PTX; 10 and 50 microM), bicucculine methiodide (BMI; 10 and 50 microM), 4-aminopyridine (4-AP; 50 microM), 8.5 mM [K+]o or 0 [Mg2+]o artificial cerebrospinal fluid. Propofol was then added in increasing concentrations and the effect on the rate of extracellular field epileptiform discharges was measured. Ictal-like discharges (> 2 Hz for > 2 s) were produced by 7.5 mM [K+]o and pilocarpine (10 microM). Propofol (30 micrograms/ml, 168 microM) completely abolished discharges induced by 8.5 mM [K+]o and at 60 micrograms/ml (337 mM) completely suppressed discharges induced by 4-AP and 0 [Mg2+]o. Propofol was less effective in reducing discharges produced by GABAA/Cl- receptor complex antagonists. Propofol at a concentration of 300 micrograms/ml (1.7 mM) was needed to reduce BMI-induced (50 microM) discharges by 77% and only reduced PTX-induced (50 microM) discharges by 20%. Ictal-like discharges produced by pilocarpine were disrupted by low concentrations of propofol (3-10 micrograms/ml, 16.9-56.2 microM) and the duration of the ictal-like discharge period was significantly reduced. We found that propofol has significant in vitro antiepileptic effects. Additionally, propofol was less effective against GABAA antagonists suggesting that the GABAA receptor complex is the site of its action.

Analysis of Variance↗
PubMed1994

Reduced transverse spinal area secondary to burst fractures: is there a relationship to neurologic injury?

A retrospective case-control study was undertaken to determine the best technique to measure neural canal encroachment at each lumbar level following burst fracture and its relationship to the presence of neurologic deficit. Only patients with postinjury CT scans demonstrating a disrupted posterior body with a retropulsed bone fragment were included. Patients were divided into groups based on the level of bony injury (T12-L5) and neurologic status. Neurologic injury was classified as follows: normal (N), root (R), or cauda equina/conus/paraplegic/paraparetic (C/P). The mean transverse spinal area (TSA, cm2), spinal canal percentage patency (PP), and midsagittal diameter (MSD) were determined for each neurologic group and lumbar level. A "calculated" TSA, based on midsagittal and anterior-posterior diameters, was also derived for each patient. The data were compared level by level and correlated with the patient's neurologic status. At L1, the critical TSA was 1.0 cm2. All patients with TSAs less than this were paraplegic. At both T12 and L1, TSAs in the range of 1.0-1.25 cm2 were observed in both normal and neurologically impaired patients. A critically significant TSA was not established for levels T12, L2, L3, L4, or L5; however, the data indicated that a smaller TSA can be tolerated at successively caudal levels without neurologic deficit. No meaningful correlation between root injury and TSA was observed. The data also indicated that measurement of TSA is a more accurate method for evaluating neural canal encroachment than PP or MSD. The "calculated" TSA is a simple, objective method for obtaining this information without the aid of a computer. This study suggests that absolute TSA should be utilized in future studies evaluating decompressive treatment of thoracolumbar pathology.

Adolescent↗
PubMed1977

Determination of 58Co-vitamin B12 absorption in pernicious anemia by use of whole-body counting: Reproducibility and control of gut transit time.

In 15 patients with pernicious anemia, the fractional retention of 58Co-cyanocobalamin (FRB12) without administration of intrinsic factor (IF) averaged 4.9% (range 0-12.7). With administration of IF, FRB12 averaged 32.7% (range 26.6--42.3) in the patients and 65.6% (range 38.8--84.6) in 16 control subjects. The gut transit time for vitamin B12 was evaluated from the excretion of radiopaque pellets given concomitantly with the 58Co-vitamin B12. The retention of the pellets was positively correlated to that of the non-absorbed 58Co-B12. Control of the gut transit time is recommended at each examination of FRB12 in order to avoid falsely high values due to the retention of non-absorbed 58Co-B12. We found a good reproducibility of FRB12 when determined in fasting subjects, and it is therefore unnecessary to give the patients a B12-free meal prior to the examination. As the FRB12 in all probability is only a little lower than the fractional absorption, the present method is applicalble for the determination of B12 absorption.

Administration, Oral↗
PubMed1976

Improvement of recalcitrant psoriasis vulgaris after tonsillectomy.

To study the effect of tonsillectomy as a possible part of the treatment of infection-released, relapsing and recalcitrant (to topical therapy and courses of penicillin) psoriasis vulgaris in children and adolescents and to test a possible correlation between tonsillitis and exacerbations of psoriasis vulgaris, a retrospective study (charts and questionnaires) of the course of psoriasis after tonsillectomy was undertaken in 74 patients with such psoriasis. Each patient served as his own control. At tonsillectomy the average age of patients and the duration of psoriasis were 14-2 years and 4-5 years, respectively, while the average follow-up period was 4-5 years. The clearing of psoriasis vulgaris was stastically significant, p less than 0-01, as 1/3 of the patients obtained clearing of psoriasis throughout the entire follow-up period, while an additional 1/3 noticed considerable improvement of their psoriasis. After having tried both topical therapy of various sorts and courses of penicillin, tonsillectomy might be taken into consideration in relapsing, recalcitrant psoriasis vulgaris in children and adolescents.

Adolescent↗
PubMed1975

Improvement of refractory psoriasis vulgaris after tonsillectomy.

In order to ascertain what effect tonsillectomy may have in the treatment of children and adolescents with recurring psoriasis vulgaris, refractory to topical therapy and courses of penicillin, and triggered by infection, and also to test a possible correlation between tonsillitis and exacerbations of psoriasis, a retrospective study of the course of psoriasis after tonsillectomy, using charts and questionnaires, was undertaken in 74 psoriatic patients. Each patient served as his won control. The average age of the patients at tonsillectomy and the duration of psoriasis were 14.2 years and 4.5 years, respectively, while the average follow-up period was 4.5 years. The clearing of the psoriasis was statistically significant (p less than 0.01) as it occurred throughout the entire follow-up period in one-third of the patients, while an additional third noticed considerable improvement of their psoriasis. After trying tropical therapies of various sorts as well as courses of penicillin, tonsillectomy might be considered for recurring, refractory psoriasis vulgaris in children and adolescents.

Adolescent↗
PubMedDate not supplied

Optimised cantilever biosensor with piezoresistive read-out.

We present a cantilever-based biochemical sensor with piezoresistive read-out which has been optimised for measuring surface stress. The resistors and the electrical wiring on the chip are encapsulated in low-pressure chemical vapor deposition (LPCVD) silicon nitride, so that the chip is well suited for operation in liquids. The wiring is titanium silicide which-in contrast to conventional metal wiring-is compatible with the high-temperature LPCVD coating process.

Journal Article↗