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Biomedical subjects

K D Green

Publications and source records attributed to K D Green.

11 recordsLinked to original sources
PubMed1999

Neurocytoma of the cauda equina. Case report.

A case of a neurocytoma involving a nerve root of the cauda equina in a 46-year-old woman is reported. The patient presented with a 2-month history of progressive left lower-extremity weakness and pain and decreased ability to walk, as well as complaints of incomplete voiding. A magnetic resonance image revealed a 7-mm oval mass that was located intrathecally and extended from T-12 to L-1 and was adjacent to a nerve root. No lesions were identified at higher vertebral levels. The mass was excised. On histological examination it was found to have classical features of a neurocytoma. To the best of the authors' knowledge, this is the first report of a neurocytoma occurring in that region. A detailed histological description of this case and review of the pertinent literature are provided.

Cauda Equina↗
PubMed1996

Selective kallikrein-kinin system activation in inbred rats differentially susceptible to granulomatous enterocolitis.

BACKGROUND & AIMS: Crohn's disease is characterized by unrestrained inflammation with a genetic component. Genetic susceptibility and activation of the kalli-krein-kinin (contact) system were investigated in experimental enterocolitis and extraintestinal inflammation induced by bacterial polymers. METHODS: Kinetics of inflammation in inbred Lewis and Buffalo rats injected subserosally with peptidoglycan-polysaccharide polymers were correlated with in vivo and in vitro activation of the contact system. RESULTS: Lewis rats had a biphasic course of enterocolitis. Acute inflammation peaked 1 day after injection, gradually decreasing until day 14 when intestinal inflammation spontaneously reactivated and persisted for 16 weeks, accompanied by arthritis, granulomatous hepatitis, anemia, and leukocytosis. Self-limited acute enterocolitis in Buffalo rats resolved by 24 days without extraintestinal involvement. Consumption of the precursor proteins prekalli-krein and high-molecular-weight kininogen indicated activation of the plasma contact system in Lewis rats and closely correlated with chronic intestinal inflammation. Contact system activation did not occur in Buffalo rats, even during acute inflammation. In vitro studies showed a decreased rate of kininogen cleavage in Buffalo plasma. CONCLUSIONS: Selective in vivo and in vitro activation of the contact system in susceptible Lewis rats suggests that this pathway is one determinant of genetic susceptibility to granulomatous enterocolitis and systemic complications.

Acute-Phase Proteins↗
PubMed1994

Aneurysm of the left middle cerebral artery caused by myxoid degeneration of the vessel wall.

BACKGROUND: Myxoid degeneration of arterial walls may result in dissection and dissecting aneurysms in extracranial and intracranial portions of cerebral arteries. Rarely, saccular aneurysms may also develop on that basis, but thus far these have only been reported in the cervical portions of the carotid arteries. We describe a case of a nondissecting aneurysm of the left middle cerebral artery caused by myxoid degeneration of the media. CASE DESCRIPTION: A 39-year-old man had acute onset of frontal headache and neck stiffness. Computed tomographic scan and lumbar puncture established the presence of subarachnoid hemorrhage. Angiography demonstrated a left middle cerebral artery aneurysm. This was clipped and the wall biopsied. Microscopically the entire thickness of the vascular wall showed marked myxoid alterations. No dissection was present. The patient had an uneventful recovery. CONCLUSIONS: This observation confirms that myxoid degeneration of arterial walls may cause aneurysms with eventual rupture even in the absence of dissection. Rare cases of this type of aneurysm have been reported to occur in the cervical portions of the carotid arteries, but this is the first reported observation of such changes involving an intracerebral artery.

Adult↗
PubMed1993

Brain stem auditory evoked potentials from bone stimulation in dogs.

Brain stem auditory evoked potential (BAEP) testing with air-conducted click stimuli can be used to diagnose sensorineural deafness in dogs if conductive deafness can be ruled out. Detection of conductive deafness can be performed by recording BAEP elicited by a vibratory stimulus transducer placed against the skull. Air- and bone-conducted BAEP were compared in dogs, varying bone stimulator placement, click polarity, and stimulus intensity. Optimal bone stimulator placement was determined to be over the mastoid process, followed by the mandible and the zygomatic arch. Condensation polarity clicks gave responses preferable to those elicited by rarefaction or alternating polarity. Bone-conducted BAEP peak latencies were significantly longer than air-conducted latencies after correction of the latencies for the air conduction time accompanying air-conducted stimuli. Significant differences between stimulus modalities were not seen for BAEP peak amplitudes or interpeak latencies. Latency-intensity and amplitude-intensity regressions had similar effects for both modalities: latencies decreased and amplitudes increased as stimulus intensity increased.

Acoustic Stimulation↗
PubMed1990

Depressive effect of isoflurane anesthesia on motor evoked potentials.

The influence of the volatile anesthetic isoflurane (Forane) on motor evoked potentials was examined in rats. To record motor evoked potentials, single-shock electrical stimulation was delivered to the forelimb representation of the motor cortex. This resulted in elicitation of a compound muscle action potential from the contralateral extensor muscles. The effect of isoflurane was examined at various concentrations ranging from 0.2 to 1.5%. With increasing concentrations of isoflurane there was a progressive increase in onset latency of the compound muscle action potential and a decrease in peak-to-peak amplitude and duration. Latencies were significantly increased over baseline values for concentrations of isoflurane from 0.5 to 1.5% (P values were 0.001 to 0.007). For the amplitude and the duration, responses at 0.5 to 1.5% isoflurane were significantly lower than baseline (P values were 0.001 to 0.007). We conclude that isoflurane anesthesia significantly changes the muscle response evoked by motor cortex stimulation in experimental animals.

Anesthesia↗
PubMed1990

Suppression of motor evoked potentials by inhalation anesthetics.

The purpose of this study was to record evoked action potentials from forearm muscles in response to single-shock supramaximal electrical stimulation of motor cortex in room air and under different concentrations (0.5-1.5%) of isoflurane, enflurane, and halothane anesthesia in rats. Anesthesia was induced with a mixture of fentanyl and droperiodol, which was then followed by 10-min inhalation of each gas anesthetic under controlled ventilation. Increasing concentrations of isoflurane (n = 12) caused a progressive increase in onset latency and a decrease in peak-to-peak amplitude and duration. Similar increases in latency and decreases in amplitude and duration occurred under enflurane (n = 10) and halothane (n = 10) anesthesia. The three anesthetics caused a significant latency increase over baseline (room air) values for concentrations from 0.5 to 1.5% (p < 0.01). The amplitude and duration of muscle responses under all three volatile anesthetics at 0.5-1.5% concentrations were significantly lower than baseline (p < 0.01). Isoflurane, enflurane, and halothane anesthesia significantly altered the muscle response evoked by motor cortex stimulation in experimental animals.

Journal Article↗
PubMed1981

Progressive and self-induced relaxation training: their relative effects on subjective and autonomic arousal to fearful stimuli.

Compared progressive relaxation training (PRT), self-induced relaxation training (SRT), and a rest quietly (RQ) control condition on measures of tonic physiological arousal and phasic physiological and subjective reactions to fearful stimuli. The Mutilation Anxiety Questionnaire was used to identify 48 male and female participants for the two training assessment sessions. Evaluation of tonic reductions in sympathetic arousal indicated: In session one, PRT and SRT were equivalent; in session two, PRT was superior to SRT. Evaluation of subjective response to fearful stimuli favored PRT/SRT over RQ for low, moderately stressful stimuli; PRT was superior to SRT for the most stressful stimuli. An analysis of reported practice between sessions indicated a negative relationship between practice of relaxation skills and response to stressful tonic physiological arousal and attenuating subjective response to stressful stimuli. The interaction between the cognitive and physiological systems and its implication for therapy are discussed.

Adult↗
PubMed1980

Validity of teacher nominations of child behavior problems.

The purpose of this study was to examine the validity of teachers' identification of problem children. Ninety-five third-grade children served as subjects. Teachers nominated children as a conduct problem, withdrawal problem, or normal, resulting in 16, 14 and 65 children being assigned to the three groups. Behavioral observation, peer sociometric ratings, and academic achievement scores were collected. The results indicated that conduct problem children differed from normal children on behavioral, sociomeptric, and academic measures, whereas withdrawal children differed from normals on the latter two measures. Conduct problem and withdrawal problem children did not differ on any of the dependent measures. The results suggest that teachers can identify children who are having difficulties in class but may be less accurate in differentiating between different types of problem children.

Child↗
PubMed1977

Effects of a procedure derived from the overcorrection principle on manipulated and nonmanipulated behaviors.

Positive practice overcorrection has been shown to be effective in reducing stereotypic self-stimulatory behaviors displayed by retarded and autistic individuals. In addition, the procedure also may increase the occurrence of appropriate behavior through intensive practice. In the present study, several stereotypic and one appropriate behavior (appropriate toy play1 displayed by two autistic children were measured before and during treatment by a positive practice in appropriate toy play overcorrection procedure. Overcorrection was introduced for each of the targeted inappropriate behaviors in sucession for both children. Results showed that overcorrection reduced all stereotypic behaviors displayed by both children. In addition, one subject displayed marked increases in the behavior practiced during overcorrection, appropriate toy play, relative to its baseline rate of occurrence. The results indicate that for some individuals, overcorrection may be effective in teaching and motivating appropriate forms of behavior as well as in reducing stereotypy.

Autistic Disorder↗