Modeling the rovibrationally excited C2H4OH radicals from the photodissociation of 2-bromoethanol at 193 nm.

This study photolytically generates, from 2-bromoethanol photodissociation, the 2-hydroxyethyl radical intermediate of the OH + ethene reaction and measures the velocity distribution of the stable radicals. We introduce an impulsive model to characterize the partitioning of internal energy in the C(2)H(4)OH fragment. It accounts for zero-point and thermal vibrational motion to determine the vibrational energy distribution of the nascent C(2)H(4)OH radicals and the distribution of total angular momentum, J, as a function of the total recoil kinetic energy imparted in the photodissociation. We render this system useful for the study of the subsequent dissociation of the 2-hydroxyethyl radical to the possible asymptotic channels of the OH + ethene reaction. The competition between these channels depends on the internal energy and the J distribution of the radicals. First, we use velocity map imaging to separately resolve the C(2)H(4)OH + Br((2)P(3/2)) and C(2)H(4)OH + Br((2)P(1/2)) photodissociation channels, allowing us to account for the 10.54 kcal/mol partitioned to the Br((2)P(1/2)) cofragment. We determine an improved resonance enhanced multiphoton ionization (REMPI) line strength for the Br transitions at 233.681 nm (5p (4)P(1/2) <-- 4p (2)P(3/2)) and 234.021 nm (5p (2)S(1/2) <-- 4p (2)P(1/2)) and obtain a spin-orbit branching ratio for Br((2)P(1/2)):Br((2)P(3/2)) of 0.26 +/- 0.03:1. Energy and momentum conservation give the distribution of total internal energy, rotational and vibrational, in the C(2)H(4)OH radicals. Then, using 10.5 eV photoionization, we measure the velocity distribution of the radicals that are stable to subsequent dissociation. The onset of dissociation occurs at internal energies much higher than those predicted by theoretical methods and reflects the significant amount of rotational energy imparted to the C(2)H(4)OH photofragment. Instead of estimating the mean rotational energy with an impulsive model from the equilibrium geometry of 2-bromoethanol, our model explicitly includes weighting over geometries across the quantum wave function with zero, one, and two quanta in the harmonic mode that most strongly alters the exit impact parameter. The model gives a nearly perfect prediction of the measured velocity distribution of stable radicals near the dissociation onset using a G4 prediction of the C-Br bond energy and the dissociation barrier for the OH + ethene channel calculated by Senosiain et al. (J. Phys. Chem. A 2006, 110, 6960). The model also indicates that the excited state dissociation proceeds primarily from a conformer of 2-bromoethanol that is trans across the C-C bond. We discuss the possible extensions of our model and the effect of the radical intermediate's J-distribution on the branching between the OH + ethene product channels.

Spinal cord and brain injury protection: testing concept for a protective device.

STUDY DESIGN: Test development for a device that could prevent both brain and spinal cord injuries during motorcycling and horseback riding. OBJECTIVE: The objective of this study was to develop a method and test a concept device that could protect against both spinal cord (SCI) and brain injuries (BI). SETTING: St Louis, Missouri, USA. METHODS: A Hybrid III dummy (that is, head, neck and torso) was used as a pendulum bob during three test conditions: (1) no protection, (2) standard motorcycle helmet and (3) SCI and BI test structure (SCIBITS). Triaxial accelerometers, a C1 force transducer and a video system were used to collect data as the dummy axially impacted a rigid barrier at speeds ranging from 10 to 605 cm s(-1). SCIBITS consisted of a fused fiberglass thoracic jacket/head shield unit. Separation between the dummy head and the head shield permitted freedom of head movement within safe limits as impact forces to the head shield were transferred from the head and neck to the upper thorax. The BI threshold was 200-300 g, and the SCI threshold was 3010 N. RESULTS: The SCIBITS protected against spinal cord injury, whereas the motorcycle helmet did not. The helmet protected against BI and the SCIBITS provided partial protection. CONCLUSIONS: The experiments describe the efficacy of an impact testing system utilizing an instrumented dummy suspended as a pendulum bob. The equipment will facilitate the design and construction of a functional device for protection against both SCI and BI in relation to both motorcycling and horseback riding.

Comparison of formal language therapy with supportive counseling for aphasia due to acute vascular accident.

A total of 60 right-handed patients with acute aphasia due to left hemispheral stroke were randomly assigned to two modes of therapy for six months, beginning one month after the ictus. Conventional speech therapy provided by professional speech pathologists twice weekly was compared with emotionally supportive counseling therapy, also provided by professional speech pathologists at the same intervals. Language function was tested periodically by the Porch Index of Communicative Ability. Fifty of the subjects were also tested at ten months after the ictus. There was no difference in the amount of improvement between the two groups.

Adrenoleukodystrophy carrier state presenting as a chronic nonprogressive spinal cord disorder.

Females who are heterozygous for adrenoleukodystrophy (ALD) can be identified biochemically. Since most carriers for this disease are asymptomatic, their diagnosis usually occurs only after neurologically abnormal male relatives have been investigated. We describe a woman with a chronic nonprogressive spinal cord syndrome secondary to the ALD heterozygote state. The neurologic condition in this patient suggests that the diagnosis of ALD should be considered in women with evidence of white matter disease.

Hereditary spastic paraplegia and hereditary ataxia, Part 2: A family demonstrating various phenotypic manifestations with the SCA3 genotype.

BACKGROUND: Clinical descriptions of the dominantly inherited ataxic motor syndromes in a 7-generation family of German origin were first reported in 1951. OBJECTIVE: To provide follow-up clinical, pathological, and genetic data for 9 patients in this family. DESIGN: Clinical histories and neurologic findings, gross and microscopic pathological features, and DNA analysis. RESULTS: Clinical presentations in this closely followed up portion of the family include fairly uniform ataxic and upper motor neuron symptoms. Nystagmus was a conspicuous and early sign, but generational anticipation was not evident. Although often present, amyotrophy was not a major source of disability. Major pathological degeneration was noted in the pons, spinal cord, and upper brainstem, where ubiquitin-immunoreactive intranuclear inclusion bodies were demonstrated. The diagnosis of Machado-Joseph disease (SCA3 [spinocerebellar ataxia type 3] genotype) was established from autopsy tissue in 1 patient and from blood specimens in 6 others. CONCLUSIONS: Clinical variation within this family and between this family and families with the SCA1 and SCA3 genotypes is so broad as to make the genetic diagnosis from clinical criteria alone practically impossible. The pathological definition of Machado-Joseph disease is more reliable, but some findings do overlap those of other genotypes. To our knowledge, the basis for the phenotypic variations in Machado-Joseph disease, genetic or otherwise, has not been established.

Acquired aphasia with convulsive disorder: course and prognosis.

Acquired aphasia with convulsive disorder is an unusual condition in childhood, characterized by loss of language function associated with a paroxysmal electroencephalogram. To determine the course and outcome of this disorder, we evaluated nine patients 10 to 28 years after the onset of aphasia. Four patients had recovered fully, one had mild language dysfunction, and four had moderate language disability. Four of the five patients with the best outcome had decreased visuoperceptive function as measured by the Revised Benton Visual Retention Test (RBVRT), whereas the three tested patients with moderate language dysfunction had normal RBVRT scores.

Congenital retardation and central motor defect with later evolution of seizure disorder, orofacial dysplasia, and amyotrophy. A clinicopathologic report.

Retarded mental and motor development was observed during the first year of life of a full-term female who had been delivered with difficulty. Generalized psychomotor seizures and dysplastic "acromegalic" facial changes began to develop when she was 8 years old, and generalized amyotrophy developed over the next several years. The course was generally progressive, and she died at age 31. A variety of clinical laboratory studies were nondiagnostic. Autopsy findings showed normal brain weight and normal-appearing cerebral hemispheres, a peculiar atrophy of the inferior portion of the cerebellar hemispheres, a demyelinating process in the dorsal columns of the cervical and thoracic spinal cord, and lateral column and motor neuron degeneration. The pathogenesis of the syndrome is undetermined.

Motor cortical neuronal activity patterns in monkeys performing several force tasks at the ankle.

Normal rhesus monkeys were conditioned at light signals to exert forces with both feet on fixed foot bars. The tasks included small and large sustained forces in plantar and dorsiflexion directions and large phasic forces in both directions. The tasks were selected to relate to behaviors known to be impaired in the upper motor neuron syndrome. Extracellular recordings were made from 226 area 4 motor cortex units (MCUs) in the hindlimb region of area 4. Ninety percent of the MCUs showed increased activity temporally related to force and EMG changes; 10% showed decreased activity exclusively. The 203 MCUs showing increased activity differed in their directional preference: half were active only in relation to development of force in one direction (unidirectional) and the remainder with forces in both directions (bidirectional). Only 28/101 of the bidirectional units were symmetric (equal activity with force in both directions). The majority were asymmetric with a greater degree of activity in one direction. Both unidirectional and bidirectional (symmetric and asymmetric) MCUs often developed increased activity not only with agonist force production but also with force relaxation in the antagonist muscles. Seventy-eight percent of the MCUs showing increased activity had phasic discharge qualities, lacking sustained activity during the prolonged force holds. Thirty-eight percent of the MCUs showing increased activity were more active with larger force, and 14% with smaller force; 48% had closely similar activity with both force levels. None of these characteristics was related to directionality. A spectrum of MCU behaviors was found that ranged in complexity from units which increased or decreased discharge with force in one direction to those responding with force production and force relaxation in both directions.

Neuronal multipotentiality: evidence for network representation of physiological function.

Extracellular action potentials of single neurons in motor cortex and rectified and integrated electromyographic activity (EMG) of gastrocnemius and anterior tibialis were recorded while a monkey performed isometric ankle plantar and dorsal flexion tasks. This study determined the consistency of neuronal behaviors across different tasks. Methods characterized neuronal behaviors by determining which behavioral event within a single task, such as the appearance of the 'go' signal, force onset, or agonist and antagonist EMG onset, was best related to changes in neuronal activity. Another method compared the temporal profiles of discharge modulation across different tasks. Of 220 neurons recorded, 44 were selected because they were consistently active in the tasks. Of these, 37 were in the precentral cortex and the remaining seven were in the postcentral cortex. Only 14 of the 33 in motor cortex were consistent in their behavioral correlations. Several had multiple changes in activity within a single task that were related to different behavioral events. Half were consistent for direction of force and a third were consistent for magnitude of force. Furthermore, there was little consistency in the temporal profiles of discharge activity for all 44 neurons across tasks. Similar modulations of discharge activity among neurons in one task were different in another task. Such inconsistencies are evidence against the cardinal cell hypothesis of physiological representation. We offer a new hypothesis analogous to connectionism in parallel distributed processing.

Resuscitation 2000: the need for improved databases in regard to neurological outcomes.

The Utstein protocol was developed to facilitate the collection of a consistent data base with which to evaluate the success or failure of resuscitative efforts. We urge redrafting of the section on neurological outcomes which should be an essential component of all outcome studies. Once this is accomplished, we believe that the use of this format should be demanded by every editor to whom an article on resuscitation is submitted.

Dorsal rhizotomy, a treatment of unproven efficacy.

On close examination of the available data, we conclude that convincing evidence of the efficacy of dorsal rhizotomy for improving motor function in cerebral palsy has yet to be shown, in spite of the fact that the operation has been used, with some variations in technique, for over 80 years. It is a procedure that is demanding of patient, family, and a large professional staff. While it does not entail a large operative risk, it must be uncomfortable during the acute and immediate recovery phases. Long-term complications and disabilities are unknown. Furthermore, at a time of soaring health costs, it is expensive. To justify its use will require carefully controlled and persuasive objective evidence of its benefits.