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Biomedical subjects

R Gerlach

Publications and source records attributed to R Gerlach.

50 records · Page 3Linked to original sources
PubMed1985

Stimulus intensity and inter-stimulus interval effects on pain-related cerebral potentials.

The inter-relationship between stimulus intensity and inter-stimulus interval (ISI) on pain-related evoked vertex potentials was studied. Sixteen subjects were tested with 4 stimulus intensities at 4 different ISIs forming 16 averaged event-related potentials for each subject. Data were analyzed in 2 ways: first by multiple regression analysis of peak-to-peak amplitudes and secondly by single-trial analysis for each subject based on a linear model employing principal component loadings as basis functions, from which were derived separate time-dependent functions describing the contributions of intensity and ISI. Peak-to-peak amplitudes of the averaged waves increased with increases in either intensity of ISI. There were no significant interactions. However, single-trial analysis revealed subtle, but consistent, differences in the peak latencies between stimulus and ISI components, suggesting that the components arise from distinct sources.

Adolescent↗
PubMed1985

Peak latency differences in evoked potentials elicited by painful dental and cutaneous stimulation.

Long-latency evoked potentials (EPs) (50-400 msec) have been obtained from humans during both noxious stimulation of tooth and cutaneous sites in studies of pain and analgesic states. This study investigated whether EPs elicited by tooth and lip stimulation differed in peak latency and whether EPs obtained during painful cutaneous stimulation showed increasing peak latency values with increased conduction distance. Twelve volunteers received painful electrical stimulation at four sites: tooth, lip, thumb, and toe in counterbalanced orders. Evoked potentials recorded at vertex were summation averaged over 128 trials. Multivariate stepwise discriminate analysis was used to determine whether any of the peak latencies of the event-related potentials differed across stimulation sites. No significant latency differences were observed across lip, thumb or toe at any of the major peaks. Since peaks of these EPs did not vary in latency with conduction distance, they appear to reflect processing at higher levels rather than sensory transmission. The negative 140 msec peak of the dental waveform occurred significantly later than the same peak at cutaneous sites.

Adult↗
PubMed1984

[Amniotic band syndrome in ultrasound].

Ultrasonographic examination during pregnancy is of great value in detecting changes in the amniotic fluid such as oligohydramnios, and severe fetal malformations, before the 24th week of pregnancy. A case of ADAM syndrome in the 22nd week of pregnancy is reported. In this case, the sonographic findings were very marked. The pathogenesis of the malformation is discussed.

Amniotic Band Syndrome↗
PubMed1983

Effects of nitrous oxide, transcutaneous electrical stimulation, and their combination on brain potentials elicited by painful stimulation.

Combinations of transcutaneous electrical stimulation (TES) and inhalation of nitrous oxide with oxygen have been used for surgical pain control and this report explored the possible synergism of these two treatments. During painful dental stimulation, 18 subjects gave pain reports while event-related potentials were recorded at vertex. Electrical stimulation was delivered bilaterally at the LI-4 acupuncture points on the hands at 20 Hz, mean = 9.65 mA intensity. Inhalation treatment was nitrous oxide 33% with oxygen. Testing was done on two days to permit evaluation of each treatment alone and their combination. Treatment sequence was counterbalanced. Base-to-peak amplitude and peak latency scores were derived for the event-related potentials under each testing condition. Both stimulation and inhalation treatments altered event-related potential scores and pain report. The combination treatment was significantly more effective than stimulation alone but was not significantly more effective than nitrous oxide alone. Nitrous oxide with oxygen alone reduced peak amplitude at 250 ms and 350 ms, as well as pain report. It increased peak latency at 100 ms. Transcutaneous electrical stimulation alone decreased peak amplitude and latency at 150 ms and increased peak latency at 350 ms. Decreased peak amplitude at 250 ms and increased peak latency at 150 ms were observed when inhalation was added to stimulation, and there was also a significant reduction in pain report. Nine control subjects were studied to demonstrate that analgesic changes were not due to repeated testing. These outcomes demonstrated no synergism between the stimulation and inhalation treatments. The data suggest that nitrous oxide blocks the effects of electrical stimulation at LI-4.

Adult↗
PubMed1982

[Sensitivity of the computer perimeter Competer in early glaucomatous loss of visual field. A controlled study].

Comparative examinations were carried out under controlled conditions in 101 eyes of 66 open-angle glaucoma patients with field defects (Stages I-III according to Aulhorn) with the Octopus and Competer computerized perimeters. The results of the Octopus perimetry were selected as a reference system to evaluate the sensitivity of the Competer in identifying early glaucomatous field defects. The interpretation of qualitative and quantitative discrepancies between the two instruments took into account the different sizes of the test fields. Of the glaucomatous field defects identified with the Octopus perimeter, 84.1% could be recognized with the Competer as well; 4% were questionably pathologic and 11.9% appeared to be false-negative in the Competers. The 11.9% false-negative results of the Competer were all due to the fact that they were scotomas beyond the test eccentricity of this perimeter. In 16.9% of the positive Competer findings the scotomas were outside the Competer test field by more than 50% of their total extent, whereas 83.1% were within the Competer test field by more than 50% of their total extent. In the light of these results it may be concluded that the Competer provides good sensitivity to detect early glaucomatous field defects once these are within 20 degrees eccentricity, while more peripherally situated scotomas will be missed. It would be advisable to enlarge the test field of the Competer to 30 degrees eccentricity. The relation of early glaucomatous field changes to disk morphology revealed that in 42.5% of the eyes definite glaucomatous disk changes were not recognized.

Adult↗
PubMed1982

[Topography of early glaucomatous visual field defects in computerized perimetry].

A total of 301 visual fields of 215 glaucoma patients exhibiting early glaucomatous field loss up to Stage II according to Aulhorn were investigated to determine the frequency distribution of absolute and relative defects at the 73 test points of Program 31 of the Octopus computer perimeter. The following results were obtained: (1) The frequency of absolute and relative defects was higher in the upper half of the visual field; (2) The frequency of both absolute and relative defects increased from 6 to 30 degrees eccentricity in the upper visual field, predominantly in the upper nasal quadrant, whereas in the temporal lower quadrant there were less absolute defects but equally frequent relative defects; (3) Defects in the nasal quadrant and above the horizontal meridian are most frequent (between 18 and 30 degrees absolute, between 12 and 30 degrees relative), while temporally of the blind spot and below the horizontal meridian they are quite rare; (4) In the upper half of the field, defects are closer to the fixation point and blind spot; the area between blind spot and macula largely free of defects. --In 71 eyes of 69 patients a similar frequency distribution was found with the Competer computer perimeter (test field 15-20 degrees eccentricity) giving good correlation with the Octopus results. --In 301 eyes of 215 patients with early glaucomatous defects the four test points in the region of the blind spot were evaluated and compared with the results of 121 eyes of 71 patients with ocular hypertension and no field changes. It appears highly probable that an increase in the size of the blind spot is associated with the incidence of field defects. --The distribution of early glaucomatous field defects in 214 eyes revealed a combination of paracentral scotomata with peripheral defects in 75.2%, exclusively peripheral scotomata in 19.6% and exclusively paracentral scotomata in 5.1%. The significance of the results with regard to the pathophysiology of glaucomatous visual field loss is discussed.

Computers↗
PubMed1982

Varying electrical acupuncture stimulation intensity: effects on dental pain-evoked potentials.

Electrical acupunctural stimulation (EAS) has repeatedly been shown in the laboratory to diminish human dental pain perception. This study compared the effects of low, medium, and high EAS levels on event-related potentials elicited by painful dental stimulation and on subjective pain report. Acupuncture was performed bilaterally at LI-4 on the hands, and each subject received all EAS levels, counterbalanced for order. Only the highest level of EAS was effective, and it reduced the pain report in addition to the amplitudes of the positive event-related potential deflections from base line at 100 and 250 msec. No dose-response effect was observed for EAS levels. The outcome suggests that the analgesic effect occurs abruptly when stimulation reaches a strong level and a subnoxious pounding sensation is elicited.

Acupuncture Therapy↗
PubMed1980

The time-distance diagram: a new method to analyze ureteral peristalsis by cineradiography.

We assessed ureteral peristalsis in dogs by cineradiography and analyzed the films in a single frame follow-up by measuring the position of bolus front and rear end in relation to the bladder and the kidney. The data were plotted as function of time in a time-distance diagram. The bolus rear end which is the active contractile rings, as proven by electromyography, travels with constant velocity. The bolus front shows remarkable changes in propagation velocity which can be explained by differences in wall forces that resist the opening of the ureteral lumen. Thus, the time-distance diagram describes precisely the constantly changing dynamics of ureteral peristalsis along the entire ureter.

Animals↗
PubMed1979

The role of Pityrosporum pachydermatis in otitis externa of dogs: evaluation of a treatment with miconazole.

The bacterial and mycotic flora were assessed in 158 ears of dogs with otitis externa and in 101 ears of healthy control dogs. Pityrosporum pachydermatis occurred in 57 per cent of ears with otitis externa and in 17 per cent of clinically healthy ears. Staphylococci and Pseudomonas aeruginosa were the predominant bacteria in otitic ears, micrococci and Bacillus spp were the most frequent isolates from clinically healthy ears. P pachydermatis, Ps aeruginosa and Candida tropicalis occurred in monoculture in a significant number of mainly chronic cases of otitis externa. A combination preparation, containing miconazole, polymyzin B and prednisolone, was highly effective in controlling the clinical signs of otitis externa and eliminating flora from the affected ears. The data presented suggest that yeasts, and especially P pachydermatis, may be significant pathogens in otitis externa and that antimycotic treatment is an essential part of the treatment of otitis externa in dogs.

Animals↗
PubMed1977

[Impulse-cytophotometric studies of spermatozoa for the demonstration of fertility disorders].

Sperm populations from 65 patients with fertility disturbances were investigated by pulse cytophotometry. The determination of the cell number showed 21 normospermias, 14 hypospermias, 19 oligospermias, 9 polyspermias, and 2 cryptospermias. As controls were used sperm samples of fertile men. The pulse cytophotometric DNA histograms were made full use quantitative and qualitative. The results of these investigations represent a methodical contribution for the diagnosis of fertility disturbances of men.

DNA↗
PubMedDate not supplied

Prospective cerebral MR study of HIV seropositive and seronegative men: correlation of MR findings with neurologic, neuropsychologic, and cerebrospinal fluid analysis.

PURPOSE: As part of a longitudinal study of human immunodeficiency virus type 1 (HIV) infection, we attempted to identify early cerebral MR findings that might correlate to clinical evidence of central nervous system involvement. METHODS: We studied 65 seropositive and 40 seronegative homosexual males using cranial MR, neurologic, immunologic, and neuropsychologic examinations. RESULTS: The incidence of mildly enlarged ventricles, sulci, and punctate areas of abnormal signal in both groups was similar in both groups. Diffuse, poorly defined areas of abnormal white matter signal were difficult to consistently identify in seropositives. Enlarged adenoidal lymphoid tissue was found in 30 (46%) of seropositives and 2 (5%) of seronegatives (P = .0001). The incidence of sinus inflammatory change was similar in the two groups. CONCLUSION: MR of intracranial contents is substantially normal in a non-AIDS HIV(+) population.

Adult↗