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Biomedical subjects

A Brashear

Publications and source records attributed to A Brashear.

28 records · Page 2Linked to original sources
PubMed1997

Rapid-onset dystonia-parkinsonism in a second family.

Rapid-onset dystonia-parkinsonism (RDP), first described in a large Midwestern family, is now reported in a second, apparently unrelated, family in which four individuals have this same syndrome. All four developed sudden onset of dysarthria, dysphagia, severe dystonic spasms, bradykinesia, and postural instability over less than 1 hour to a few days. Three of the four had stable limb dystonia for several years preceding the onset of combined dystonia-parkinsonism. Treatment with levodopa/carbidopa provided little benefit. We propose diagnostic criteria for RDP and further define the spectrum of this unusual disease.

Adolescent↗
PubMed1997

Costs of treating dystonias and hemifacial spasm with botulinum toxin A.

Botulinum toxin (BTX) has become a safe and effective therapeutic tool in the treatment of a variety of neurological disorders, especially dystonias. One major disadvantage, however, is the high cost of a single injection of BTX. In this study of 835 patients, we calculated the cost of treatment with BTX serotype A (BTX-A) for different dystonias and hemifacial spasm. The annual expenditure per patient for BTX-A injections in this cohort totalled (mean +/- standard deviation) 1030 Deutschmarks (DM) [1996 values] +/- DM610 [$US570 +/- $US340; 230 +/- 130 pounds sterling (Pound)] for blepharospasm (n = 158), DM1450 +/- DM1520 ($US800 +/- $US830; 310 Pounds +/- 280 Pounds) for craniocervical dystonia (n = 148), and DM1480 +/- DM780 ($US810 +/- $US430; 330 Pounds +/- 180 Pounds) for oromandibular dystonia (n = 16), while the treatment of cervical dystonia consumed DM4590 +/- DM2060 ($US2520 +/- $US1130; 960 Pounds +/- 420 Pounds) [n = 362] per patient. In order to alleviate symptoms in patients with hemifacial spasm (n = 151), DM510 +/- DM270 ($US280 +/- $US150; 110 Pounds +/- 60 Pounds) had to be spent annually. The expenses for surgical therapy for cervical dystonia were DM10,120 +/- DM1900 (n = 54). No major differences concerning expenditure could be found in this study between the 2 available preparations of BTX. However, there appeared to be a lower rate of adverse effects with the Botox formulation, compared with the Dysport formulation, of BTX-A (this difference was statistically significant, i.e. p < 0.001). Although the cost of an individual injection is high, other cost factors also substantially contribute to the societal costs of adult-onset dystonias. Some of these costs may be attenuated with the use of BTX. The subjective and objective relief of these socially devastating and sometimes painful conditions rewards the expenditure associated with the use of BTX-A.

Adult↗
PubMed1996

The influence of the reference electrode on CMAP configuration: leg nerve observations and an alternative reference site.

Peroneal and tibial compound motor action potentials (CMAP) recorded using the standard belly-tendon montage have different configurations. The peroneal CMAP is a smooth dome shape, while the tibial CMAP has a slow-rising initial component followed by a higher amplitude negative peak. To evaluate possible causes of these differences we investigated the individual activity recordable at the belly and tendon electrodes by using a referential montage with the opposite foot as the reference. This type recording shows that the peroneal belly site produces most of the nerve CMAP, whereas the tendon site generates most of the high tibial CMAP. Some features and technical problems of referential CMAP recording using an opposite limb reference are shown. An alternative method using an ipsilateral distal leg reference site is described. A montage which separately records the activity at the belly or tendon electrodes may provide new insight into mechanisms of commonly observed nerve conduction phenomena.

Action Potentials↗
PubMed1996

Variable phenotype of rapid-onset dystonia-parkinsonism.

Rapid-onset dystonia-parkinsonism (RDP) is an autosomal dominant disorder characterized by the rapid onset of dystonic spasms and parkinsonism over a period of a few hours to weeks after their onset. We have seen two additional members of this previously reported family with RDP who present with a more gradual progression of their disorder over 6-18 months. One of these individuals experienced the rapid progression of symptoms 2 years after an initial stabilization of his condition. The RDP phenotype is variable, and presentation may be gradual in some cases. Cerebrospinal fluid neurotransmitter levels in these two and other family members suggest involvement of the dopaminergic pathways in RDP.

Adolescent↗
PubMed1996

Ethylene oxide neurotoxicity: a cluster of 12 nurses with peripheral and central nervous system toxicity.

Ethylene oxide (EO) is commonly used to sterilize heat-sensitive products used by hospital patients and personnel. Ethylene chlorohydrin (EC), a by-product, is considered highly toxic. We report a cluster of 12 operating-room nurses and technicians who developed symptoms after a 5-month exposure to high levels of EO and EC in disposable surgical gowns. All patients reported a rash on the wrist where contact was made with the gowns, headaches, and hand numbness with weakness. Ten of 12 patients complained of memory loss. Neurologic evaluation revealed neuropathy on examination in nine of the 12 patients, elevated vibration threshold in four of nine, abnormal pressure threshold in 10 of 11, atrophy on head MRI in three of 10, and neuropathy on conduction studies in four of 10. Neuropsychological testing demonstrated mild cognitive impairment in four of six patients. Sural nerve biopsy in the most severely affected patient showed findings of axonal injury. Several patients in this group display signs of peripheral and CNS dysfunction following exposure to EO. Possible mechanisms of neurotoxicity include direct exposure of peripheral nerves through cutaneous absorption and central involvement through inhalation and vascular dissemination. The frequency of central and peripheral nervous system symptoms, supported by objective testing in these EO-exposed patients, suggests other healthcare personnel may be at similar risk.

Adult↗
PubMed1993

The influence of the reference electrode on CMAP configuration.

The ulnar, hypothenar compound muscle action potential often shows a double-peaked configuration in the negative phase component while the median, thenar potential has a simple dome shape. To investigate the origin of these differences we evaluated the activity at the belly and tendon electrode locations by referencing those sites to an electrode on the contralateral hand. The tendon sites are not electrically inactive. The ulnar tendon electrode contributes a large amplitude potential which corresponds to the second peak of the ulnar belly-tendon potential. The median tendon electrode contributes only a minimal component to the negative phase of the belly-tendon potential. The distribution of such potentials throughout the hand is evaluated and possible mechanisms for the presence of a tendon potential as well as the differences between ulnar and median sites are discussed.

Action Potentials↗
PubMed1993

Rapid-onset dystonia-parkinsonism.

We studied a large family with a previously undescribed, autosomal dominant dystonia-parkinsonism syndrome. We chose to call the disorder "rapid-onset dystonia-parkinsonism" (RDP) based on the unusually rapid evolution of signs and symptoms. Affected individuals developed dystonia and parkinsonism between 14 and 45 years of age. The onset was acute in six individuals with the abrupt onset of symptoms over the course of several hours, and subacute in four others who had evolution over several days or weeks. Thereafter, progression of symptoms was usually very slow. Two had intermittent focal dystonia without parkinsonism, and one obligate gene carrier was asymptomatic at 68 years. CSF levels of homovanillic acid were decreased in the two individuals tested, but dopaminergic therapy provided only slight benefit. The DYT1 gene responsible for early-onset, generalized idiopathic torsion dystonia in Jewish and some non-Jewish families has been mapped to chromosome 9q34. Linkage analysis with three markers near the DYT1 gene showed several obligate recombinations, excluding DYT1 as a candidate gene for RDP. We believe RDP is unique and should be classified separately from other forms of hereditary dystonia-parkinsonism.

Adolescent↗
PubMed1983

A spectrophotometric, enzymatic assay for D-3-hydroxybutyrate that is not dependent on hydrazine.

Because of the potential carcinogenic properties of hydrazine and because of other health hazards associated with its use in the laboratory, an enzymatic assay has been developed for D-3-hydroxybutyrate that is not dependent on hydrazine to drive the reaction toward completion. The use of a high concentration of NAD+ and a buffer at pH 9.5 resulted in a favorable conversion of D-3-hydroxybutyrate to acetoacetate by D-3-hydroxybutyrate dehydrogenase even though the reaction favors D-3-hydroxybutyrate formation under physiological conditions. The assay was also completed faster than previous assays using hydrazine so that the amount of enzyme used for the assay could be reduced. The recovery of D-3-hydroxybutyrate added to liver samples was 98 +/- 1% (mean +/- SEM, n = 6). The assay was found to be suitable for the measurement of D-3-hydroxybutyrate in samples such as perchloric acid extracts of isolated hepatocytes even when the acetoacetate to D-3-hydroxybutyrate ratio was 4 to 1. This assay presents a reliable alternative to the use of hydrazine and may be used for the assay of D-3-hydroxybutyrate in a variety of physiological and experimental samples.

3-Hydroxybutyric Acid↗
PubMed1983

The ventilatory response to intravenous and ventriculo-cisternal theophylline.

The stimulatory effect of theophylline on ventilation was studied in nine anesthetized dogs. Theophylline infused intravenously (10 mg/kg bolus, then 1.00 mg/kg/hr) for 210 minutes significantly increased the minute volume of ventilation (P less than 0.05 at 210 minutes). After a recovery period of seven to fourteen days, ventriculo-cisternal perfusion was performed with mock cerebrospinal fluid (CSF). Theophylline added to the mock CSF did not significantly change the minute ventilation. ventriculo-cisternal perfusion utilizing mock CSF not containing theophylline combined with intravenous theophylline infusion stimulated ventilation similarly to the previous intravenous theophylline infusion. Therefore, stimulation of ventilation by theophylline appears to relate to the serum theophylline concentration and not the ventricular CSF theophylline concentration.

Aminophylline↗