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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
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↗
PubMed1981

Mapping of functional activity in brain with 18F-fluoro-deoxyglucose.

The efficacy of using the 18F-fluoro-deoxyglucose (18F-DG) for measuring regional cerebral glucose utilization in man during functional activation is demonstrated. Normal male volunteers subjected to sensory stimuli (visual, auditory, tactile) exhibited focal increases in glucose metabolism in response to the stimulus. Unilateral visual hemifield stimulation caused the contralateral striate cortex to become more active metabolically than the striate cortex ipsilateral to the stimulated hemifield. Similarly, stroking of the fingers and hand of one arm with a brush produced an increase in metabolism in the contralateral postcentral gyrus compared to the homologous ipsilateral region. The auditory stimulus, which consisted of monaural listening to either a meaningful or nonmeaningful story, caused an increase in glucose metabolism in the right temporal cortex independent of which ear was stimulated. These results demonstrate that the 18F-DG technique is capable of providing functional maps in vivo in the human brain.

Adult↗
PubMed1979

Bed occupancy by diabetic patients.

The Royal Newcastle Hospital Diabetic Education and Stabilization Centre was instituted primarily to improve diabetics' understanding of their disease and its everyday management. Simultaneously with a five-day education course, stabilization if insulin-dependent diabetics was undertaken on an outpatient basis. In order to disseminate diabetic education as widely as possible, trained nurses from near and far were included in each course. It is believed that these nurses will be able to offer good advice to diabetics who have no other source of reliable information. By actively attempting to reduce hospital bed occupancy by diabetics there has been a reduction of 1400 bed days per year. It is recommended that similar centres be instituted throughout Australia.

Acidosis↗
PubMed1979

The [18F]fluorodeoxyglucose method for the measurement of local cerebral glucose utilization in man.

A method has been developed to measure local glucose consumption in the various structures of the brain in man with three-dimensional resolution. [18F]-2-deoxy-2-fluoro-D-glucose is used as a tracer for the exchange of glucose between plasma and brain and its phosphorylation by hexokinase in the tissue. A mathematical model and derived operational equation are used which enable local cerebral glucose consumption to be calculated in terms of the following measurable variables. An intravenous bolus of [18F]-2-deoxy-2-fluoro-D-glucose is given and the arterial specific activity monitored for a predetermined period of from 30 to 120 minutes. Starting at 30 minutes, the activity in a series of sections through the brain is determined with three-dimensional resolution by an emission tomographic scanner. The method was used to measure local cerebral glucose consumption in two normal volunteers. The values in gray matter structures range from 5.79 mg/100 g per minute in the cerebellar cortex to 10.27 in the visual cortex, whereas, in white matter structures, the values range from 3.64 mg/100 g per minute in the corpus callosum to 4.22 in the occipital lobe. Average values for gray matter, white matter, and whole brain metabolic rates, calculated as a weighted average based on the approximate volume of each structure, are 8.05, 3.80, and 5.90 mg/100 g per minute, respectively. The value of 5.9 mg/100 g per minute compares favorably with values previously reported.

Adult↗
PubMed1979

Selective mass treatment in a venereal disease control program.

To control syphilis among prostitutes and seasonal farm workers in Fresno County, California, we developed a program of selective mass treatment of prostitutes. From August 1976 to July 1977, 512 women entered the program. Overall, 4.6 per cent of women treated prophylactically for syphilis were actually infected. Compared to cases in the previous year, infectious syphilis cases among prostitutes and seasonal farm workers decreased 51.3 per cent and 26.8 per cent, respectively.

Adult↗
PubMed1978

Toward the measurement of primary care.

The renaissance of rhetoric about primary care--"continuous, coordinated, comprehensive, family-centered"--has paralleled the growth of entrants into formal training programs. The extent to which primary care is actually practiced this way has not been examined, nor have the routes to preparing for it. A preliminary set of measurements is suggested.

Adolescent↗