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Biomedical subjects

P Zimmermann

Publications and source records attributed to P Zimmermann.

At least 109 records · Page 6Linked to original sources
PubMed1986

Event-related brain potentials (P300) and neuropsychological deficit in patients with focal brain lesions.

Sixteen patients with chronic focal brain lesions were investigated with an acoustic P300 test and psychological tests of spatial abilities (Maze Tracing Speed Test, Form Board Test), cognitive speed (Sequential Number Connection Test), categorization (Figure Sorting Test), verbal fluency and vigilance. Neither the psychological battery nor P300 analysis discriminated frontal from retrorolandic brain lesions. Abnormalities of P300 significantly correlated with impairments in those psychological tests which had a spinal component in common. We suggest that abnormality of the P300 with focal brain damage rather indicates higher mental function impairment than direct effects of the lesion.

Adult↗
PubMed1985

Long-term effects of partial callosal lesions. Preliminary report.

Ten patients with partial callosal lesions were investigated with a broad scale neuropsychological assessment. Nine patients with a variety of lesions affecting midline structures have been operated using a direct transcallosal approach, one patient with a callosal lipoma remained unoperated. Sophisticated studies of the interhemispheric transfer of somaesthetic and perceptual motor tasks, as well as psychometric testing related to parameters of memory and attention performance were applied. The results indicate that there is no clear correlation between the site of callosal lesion and clinical symptoms. Although special disconnecting symptoms due to callosal dissection could be found, they didn't reach clinical significance. The most severe symptoms of impairment were caused by the extracallosal pathology. The results indicate that the transcallosal approach is a safe and feasible alternative in the management of pathological lesions in the midline region.

Adolescent↗
PubMed1985

Collaborative WHO xylitol field studies in Hungary. I. Three-year caries activity in institutionalized children.

The aim of this 3-year field study was to assess the value of partial substitution of sucrose with peroral xylitol (14-20 g/day) as a caries-preventive measure (X group) in comparison with systemic administration of fluoride (F group) and restorative treatment procedures solely (C group). An F dentifrice was used unsupervised in the X and F groups, the former containing 10% xylitol. The C group used customary, predominantly F-free dentifrices distributed by the local health authorities. The final material consisted of 689 institutionalized children (6-11 years). Caries was scored yearly in duplicate by two continuously calibrated teams. At base line the X group had a significantly higher caries prevalence than the F and C groups. The 3-year DMFS increment was 4.2 in the X group, 6.5 in the F group, and 7.7 in the C group. The corresponding ratio (RS) between caries incidence and the tooth surface population at risk was RSx, 4.9; RSF, 6.6; and RSC, 8.6. It is concluded that dietary xylitol in solid sweets resulted in a lower increment of caries than obtained in the F and C groups (p less than 0.001, covariance analysis, with base-line prevalence, number of permanent teeth, and visible plaque index as covariants).

Animals↗
PubMed1985

Collaborative WHO xylitol field studies in Hungary. VII. Two-year caries incidence in 976 institutionalized children.

The aim was to assess caries increment as influenced by partial substitution of sucrose by xylitol (X group) over a 2-year period in comparison with systemic fluoride (F group) and restorative treatment only (C group). The study differed from the 3-year field study of the same series primarily in that existing base-line differences were eliminated because the protocol required that all the new subjects entering the institutions in the 1st year were to be included for a 2-year trial. During this period the number of dropouts was 243 (19.9% of all subjects), the final material consisting of 976 children (6-12 years old). The 2-year DMFS increment was 3.8 in the X group, 4.8 in the F group, and 6.0 in the C group. The corresponding ratio (RS) between caries incidence and the tooth surface population at risk was RSX, 4.5; RSF, 5.5; and RSC, 7.5. The xylitol regimen resulted in a lower increment of caries than measured in the F and C groups (p less than 0.001; convariance analysis, with base-line prevalence, number of permanent teeth, and visible plaque index as covariants.

Cariostatic Agents↗
PubMed1984

Effects of a GABA-mimetic drug (sodium valproate) on visually evoked potentials in chronic schizophrenics.

Data were obtained from 14 chronically schizophrenic women (age 40-59) living in the same ward of a psychiatric hospital (Marburg, FRG), and having been treated with clozapine (450-600 mg/day) during the last 2 years. The uncontrolled study was initiated by the addition of sodium valproate (900 mg/day) for 3 months. The observation commenced after the discontinuation of the valproate medication with the evaluation of the symptoms (Brief Psychiatric Rating Scale, BPRS) and the visually evoked potentials (VEP). The VEP were recorded after 3, 12 and 30 days and the rating was repeated after 4 weeks. No significant changes in symptomatology were obtained with the BPRS in patients under combination therapy in comparison with the scores 30 days after discontinuation of the valproate medication. On the other hand, after single flash stimulation, the amplitudes of the components N110, P260, and N300 of the VEP were significantly (p less than 0.05) increased during the same time interval. These findings are interpreted as an expression of an inhibiting action of the GABA system on the reactivity of the visual system in chronic schizophrenics induced by the comedication of sodium valproate.

Adult↗
PubMed1984

Variability of evoked-potential response to regularly repeated stimulation with checkerboard pattern-reversal and flashlight in healthy volunteers.

Pattern-reversal and flash-evoked potentials (EP) were analyzed in 20 healthy male volunteers (age 40-49 years) to investigate the response variability to monotonously repeated stimulation. The EPs were recorded over O2-T6. Each stimulus train consisted of 256 sweeps. The digitized signals were averaged in four consecutive, non-overlapping blocks, each consisting of 64 sweeps. The subjects were classified according to Q-factor analysis on the basis of five primary personality factors. Two-factorial analyses of variance (repeated measurement) were calculated on the baseline differences with the personality type as grouping factor. The amplitudes of the pattern-reversal EP were increased, those of the flash EP, with one exception, decreased as the stimuli were successively repeated. Differential effects of the personality type on the latencies of the positive components of both VEPs were observed.

Adult↗
PubMed1983

Testosterone-induced alterations in the reactivity pattern of the neurons in the arcuate nucleus of male mice. A karyometric study.

The effects of testosterone administration on the hypothalamic arcuate nucleus were studied in adult male mice by means of karyometry. Four animals per group were sacrificed 1, 2, and 3 h after intramuscular injection of 100 micrograms testosterone propionate/100 g body weight. The nuclear diameter of neurons was measured in serial coronal sections. Testosterone induced an increase in the nuclear diameter of neurons located in the dorsal and medial periventricular zones of the arcuate nucleus. The neurons exhibiting the greatest changes in nuclear diameter were situated in the rostral portion of the nuclear area examined. In the central portion of the arcuate nucleus no response to testosterone was found. The present data support previous observations showing mosaically arranged nerve-cell groups in this hypothalamic nucleus.

Animals↗
PubMed1983

Effect of fluoridated milk on caries: 3-year results.

The effect of fluoridated milk consumption has been investigated in a follow-up study of 269 children aged 3-9 years. Children consumed 200 ml of milk daily, fluoridated in the groups 3-5 years with 0.4 mg F-, and in those aged 6-9 years with 0.75 mg F-, for 300 days yearly. The caries data were analyzed with special regard to changes in the DMF values of the permanent first molars, the yearly examination data of the corresponding age groups compared and correlated with the length of fluoridated milk consumption. Statistical analysis of the permanent first molar data showed significant negative correlation between DMF means and length of fluoridated milk consumption in children 5-6 years old at the time of evaluation. The caries reduction after 3 years was 74% and statistically significant (P less than 0.001). In children 7-9 years old the caries reduction of the permanent first molars was less, and statistically not significant. A slight reduction of DMFS mean values in the front teeth of this group could be observed.

Animals↗
PubMed1983

Diurnal periodicity of lateral asymmetries of the visual evoked potential in healthy volunteers.

Visual evoked potential (VEP) was analyzed in 24 healthy male volunteers (age: 25-35 years) between 7.00 a.m. and 4.00 p.m. to evaluate possible diurnal variation in hemispheric differences of the response to a diffuse or 1 degree flash and checkerboard pattern-reversal (stimulation: binocular). VEP was recorded over O1-A1 and O2-A2, and 64 exposures were averaged during each session. After diffuse and 1 degree flash stimulation the amplitudes of early components (latencies less than 140 ms) were higher over the right hemisphere (O2-A2) than over the left (O1-A1) in the morning. These differences disappeared during the afternoon. Late components (latencies greater than 250 ms) exhibited higher amplitudes over the left than over the right hemisphere during the whole experiment. With checkerboard pattern-reversal stimulation such a time-dependent change in the amplitudes of VEP between both hemispheres was not measurable.

Adult↗
PubMed1982

Estrogen-dependent changes in the functional interrelationships among neurons, ependymal cells and glial cells of the arcuate nucleus. Cytometric studies in the female albino mouse.

The synchronizing effect of ethinylestradiol (4 micrograms/g b.w.) on neurons of the arcuate nucleus 700-950 micrometers caudal to the posterior edge of the optic chiasma was studied by karyometry in 6-week-old albino mice during proestrus. The caudal portion of the arcuate nucleus was identified as the most estrogen-sensitive subdivision; all neurons showed an increase in their nuclear area (mean transect, profile area of the nucleus) 1 h following administration of ethinylestradiol. This hypothalamic region was selected for the subsequent electron-microscopic cytometric study to analyze functional interrelationships among neurons, ependymal cells and glial cells. Six and 12 days after ovariectomy no significant change in the nuclear area of neurons and ependymal cells was found 850-950 micrometers behind the posterior slope of the optic chiasma, but the neurons exhibited a decrease in the number of polyribosomes, the volume fraction (Vvmi) and the surface density of the inner membrane of mitochondria (Svmi). A similar decrease in Vvmi and Svmi was measured in the apical part of ependymal cells and in the pericapillary profiles of ependymal and glial cells, which was accompanied by a reduction in the surface density of ependymal processes extending into the ventricular lumen. In addition, no change of Vvmi and Svmi was seen in the basal subnuclear part of ependymal cells. This bipolar functional reaction of ependymal cells after ovariectomy is discussed as an indicator of ependymal control of neuronal activity by sequestering biologically active agents, e.g., transmitters of neurohormones, in their apical and basal extensions facing the ventricular surface or the pericapillary space.

Animals↗