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Biomedical subjects

J Fowler

Publications and source records attributed to J Fowler.

At least 127 records · Page 7Linked to original sources
PubMed1987

Orbital cyst formation associated with Gelfilm use.

Two patients developed cystic lesions in the anterior orbit 21 and 26 months after repair of blow-out fracture with orbital floor Gelfilm implants. Both patients had associated motility disturbances. Both lesions were surgically excised and found to be cystic in nature and filled with glistening gelatinous material consistent with partially absorbed, encysted gelatin film (Gelfilm). Histologically, a fibrous capsule was present; the contents of the cyst were not pathologically identifiable since they dissolved during fixation. Postoperatively, the motility disturbances improved in each patient.

Adult↗
PubMed1986

Sustained hyperexcitability elicited by repetitive electric stimulation of organotypic hippocampal explants.

Sustained or complex evoked extracellular slow-wave field potentials were recorded in the CA3/2 areas of organotypic hippocampal explants following stimulation of the dentate area. After repetitive electric stimulation, these discharges became more complex and/or self-sustaining. Self-sustaining discharges continued to occur for the duration of the experiment (15 min-10 h). These slow-wave discharges were evoked (or occurred spontaneously) over a wide range of extracellular K+ concentrations (3-9 mM) without addition of pharmacologic inhibitory antagonists, whereas in some explants raising extracellular K+ from 5.9 to 8-9 mM resulted in spontaneous discharges. The observation that epileptiform discharges in hippocampal explants often occurred spontaneously, were elicited by repetitive electric stimulation, and were recorded at K+ levels which are generally ineffective in acute adult hippocampal slices, indicates that excitability of these CNS explants may be significantly increased following altered neuronal and synaptic development (and/or reorganization) under isolated conditions in culture.

Animals↗
PubMed1986

Dendritic patterns of granule cells in organotypic explants of fetal and neonatal mouse hippocampal formation.

Granule and granule-like neurons were labeled by Golgi and HRP techniques in the dentate area of fetal and neonatal organotypic hippocampal explants after 1 day-8 weeks in vitro. These cells resembled granule cells labeled in situ with similar techniques, although the dendritic pattern and spine development were not as elaborate as observed on granule cells from adult rodents. Many of these neurons retained basilar or multiple dendrites after 8 weeks in culture, a characteristic often associated with immature granule cells, granule cells in the reeler mutant mouse and tissues removed from human epileptic foci.

Animals↗
PubMed1985

Glucose metabolic rate kinetic model parameter determination in humans: the lumped constants and rate constants for [18F]fluorodeoxyglucose and [11C]deoxyglucose.

The rate constants and lumped constants (LCs) for [18F]fluorodeoxyglucose ([18F]FDG) and [11C]deoxyglucose ([11C]DG) were determined in humans for the glucose metabolic rate kinetic model used to measure local cerebral glucose consumption. The mean values (+/- SE) of the LCs for [18F]FDG and [11C]DG are 0.52 +/- 0.028 (n = 9) and 0.56 +/- 0.043 (n = 6), respectively. The mean values (+/- SE) of the rate constants k*1, k*2, k*3, and k*4 for [18F]FDG for gray matter are 0.095 +/- 0.005, 0.125 +/- 0.002, 0.069 +/- 0.002, and 0.0055 +/- 0.0003, respectively. The corresponding values for white matter are 0.065 +/- 0.005, 0.126 +/- 0.003, 0.066 +/- 0.002, and 0.0054 +/- 0.0006, respectively. Using these values and previously published values for the rate constants for [11C]DG, the average whole-brain metabolic rates for glucose in normal subjects measured with [18F]FDG and [11C]DG are 5.66 +/- 0.37 (n = 6) and 4.99 +/- 0.23 (n = 6) mg/100 g/min, respectively. These values are not significantly different (t = 1.56, p greater than 0.10) and agree well with reported values in the literature determined by means of the Kety-Schmidt technique.

Adolescent↗
PubMed1985

Persistence of cerebral metabolic abnormalities in chronic schizophrenia as determined by positron emission tomography.

Local cerebral metabolic rates were determined by positron emission tomography and the deoxyglucose method in a group of 10 chronic schizophrenic subjects before and after somatic treatment and in eight normal subjects. Before treatment, schizophrenic subjects had markedly lower absolute metabolic activity than did normal controls in both frontal and temporal regions and a trend toward relative hyperactivity in the basal ganglia area. After treatment, their metabolic rates approached those seen in normal subjects in nearly all regions except frontal. Persistence of diminished frontal metabolism was manifested as significant relative hypofrontality. These findings suggest specific loci of aberrant cerebral functioning in chronic schizophrenia and the utility of positron emission tomography in characterizing these abnormalities.

Adult↗
PubMed1984

Hyperexcitability in organotypic mouse hippocampal explants.

We have developed an organotypic hippocampal tissue culture model for analyses of sustained hyperexcitability in which repetitive electric stimulation of the dentate area enhances the amplitude and complexity of evoked normal and epileptiform field potentials recorded extracellularly from CA3/2 areas of neonatal mouse hippocampal explants. In explants where spontaneous field potentials are not detectable at the onset of the experiment, brief repetitive electric stimulation elicits self-sustained epileptiform discharges that continue for the duration of the recorded period (2-10 hours). Lowering the extracellular Ca++ level to 0.1-0.2 mM markedly attenuates these discharges and repetitive stimulation during a 2-4 hr period fails to elicit hyperexcitability. When tested after return to normal media repetitive stimulation can elicit hyperexcitability. Raising the extracellular K+ levels to 8-9 mM enhances the complexity of evoked as well as spontaneous field potentials and, in some cases, elicits self-sustained epileptiform discharges in the absence of repetitive electric stimulation.

Animals↗
PubMed1982

Use of 2-deoxy-D[1-11C]glucose for the determination of local cerebral glucose metabolism in humans: variation within and between subjects.

The deoxyglucose technique for the measurement of local cerebral glucose metabolism (LCMRgl) has been widely applied in animals utilizing 14C-deoxyglucose and in humans employing 18F-fluorodeoxyglucose. Repeat studies in humans over a relatively brief period of time have not been possible because of the 110-min half-life of fluorine-18. With the synthesis of 11C-deoxyglucose it has now become possible to utilize this short-lived (20 min) tracer for the measurement of LCMRgl and to determine its variability within subjects over a 2-h period. The kinetic rate constants for 11C-deoxyglucose were determined for gray and white matter and found to be very similar to those for 18F-fluorodeoxyglucose, suggesting that these two analogues of glucose have similar affinities for the facilitated transport system and are similar substrates for hexokinase in the brain. The coefficient of variation of repeated measurements of LCMRgl in a series of six normal subjects was 5.5% to 8.7% for various gray matter structures and 9.7% and 14.0% for white matter structures. The pattern of cerebral metabolic rates is relatively constant in a given individual when the conditions of the study are unchanged. The ability to make repeat measurements in the same subject reduces the variance due to between-subject differences, allowing smaller changes in LCMRgl to be detected with confidence.

Brain↗
PubMed1981

Metabolic mapping of functional activity in human subjects with the [18F]fluorodeoxyglucose technique.

The 2-[18F]fluoro-2-deoxy-D-glucose technique was used to measure regional cerebral glucose utilization by human subjects during functional activation. Normal male volunteers subjected to one or more sensory stimuli (tactile, visual, or auditory) exhibited focal increases in glucose metabolism in response to the stimulus. Unilateral visual hemifield stimulation caused the contralateral striate cortex to become more metabolically active than the striate cortex ipsilateral to the stimulated hemifield. Similarly, stroking the fingers and hand of one arm with brush produced an increase in metabolism in the contralateral postcentral gyrus, compared with the homologous ipsilateral region. The auditory stimulus, which consisted of a monaurally presented factual story caused an increase in glucose metabolism in the auditory cortex in the hemisphere contralateral to the stimulated ear. These results demonstrate that the technique is capable of providing functional maps in vivo related to both body region and submodality of sensory information in the human brain.

Adult↗
PubMed1981

Are fibre supplements really necessary in diverticular disease of the colon? A controlled clinical trial.

Fifty-eight patients with uncomplicated diverticular disease of the colon took bran crispbread, ispaghula drink, and placebo for four months each in a randomised, cross-over, double-blind controlled trial. Assessments were made subjectively, using a monthly self-administered questionnaire, and objectively, by examining a seven-day stool collection at the end of each treatment period. In terms of a pain score, lower bowel symptom score (the pain score and sensation of incomplete emptying, straining, stool consistency, flatus, and aperients taken), and total symptom score (belching, nausea, vomiting, dyspepsia, and abdominal distension) fibre supplementation conferred no benefit. Symptoms of constipation, however, when assessed alone, were significantly relieved. Both fibre regimens produced the expected changes in stool weight, consistency, and frequency. It is concluded that dietary fibre supplements in the commonly used doses do no more than relieve constipation. Perhaps the impression that fibre helps diverticular disease is simply a manifestation of Western civilisation's obsession with the need for regular frequent defecation.

Adult↗