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Biomedical subjects

B Swartz

Publications and source records attributed to B Swartz.

18 recordsLinked to original sources
PubMed2006

Optimal evaluation of digital electroencephalograms.

Currently available digital EEG equipment provides considerably greater opportunities for clinical data analysis than is generally appreciated especially when appropriate software is used. Data from 7 different laboratories that had been obtained for routine diagnostic evaluations on 7 different EEG instruments and stored on compact disks were investigated. Since the instruments do not filter the data at input, ultra slow activity down to 0.01 Hz is currently being recorded but the attenuation factor is instrument dependent. Nevertheless, relevant clinical information is potentially available in these data and needs to be explored. Several examples in regard to epilepsy are presented. Determination of seizure onset may depend on the frequencies that are examined. The use of appropriate filter settings and viewing windows for the clinical question to be answered is stressed. Differentiation between simple and complex spike wave discharges, as well as spread of spikes, can readily be achieved by expanding the time base to 1 or 2 seconds and placing a cursor on the peak of the negative spike. Latencies in the millisecond range can then become apparent. EEGs co-registered with MEG should be evaluated with the same software in order to allow an adequate assessment of the similarities and differences between electrical and magnetic activity. An example of a comparison of EEG, planar gradiometers and magnetometers for an averaged spike is shown.

Brain Diseases↗
PubMed2000

Electropalatographic and spectrographic descriptions of allophonic variants of /1/.

Prevocalic and postvocalic /1/ were investigated in three adult subjects utilizing a combination of electropalatographic and acoustic techniques. Results indicated that prevocalic /1/ was characterized by both alveolar and lateral lingua-palatal contact, while postvocalic /1/ was primarily alveolar contact only. Acoustically, prevocalic /1/ had a lower first formant and higher second formant than postvocalic /1/. In addition, the second and third formants were often weak or absent for prevocalic but not postvocalic /1/. Vowel context had a greater effect on the electropalatographic and acoustic characteristics of prevocalic than postvocalic /1/. Models that relate physiological and acoustical aspects of speech were utilized to account for the observed results.

Adult↗
PubMed1996

Long-term changes in marginal and periapical periodontal conditions in patients with fixed prostheses: a radiographic study.

Patients treated at a prosthodontic department during the years 1968-73 with fixed restorations (at least five units) were followed up in 1991-92. The aim of the present study was to compare marginal and periapical periodontal conditions on radiographs from 1968-73 and 1991-92 and relate the changes to the results of the prosthodontic treatment. In the group in which the restorations remained unchanged, 90% of the abutments that were not root filled and showed no periapical radiolucency when the restorations were placed, were still not root filled and showed no periapical radiolucency at the follow-up examination. The corresponding figure for the group in which the restorations had been replaced was only 69%. The changes in marginal bone levels also differed between the groups. In the group with remaining restorations, 66% of the surfaces were given the same score on a five-point scale both in 1968-73 and in 1991-92. In the other group, only 54% were scored the same on both occasions. Thus, unfavourable changes in both periapical and marginal periodontal conditions were associated with poorer results for the fixed restorations.

Adult↗
PubMed1993

Correction of implant malalignment by segmental osteotomy: a case report.

This case report demonstrates that the position of malaligned osseointegrated implants can be corrected by a segmental osteotomy procedure with no loss of implants or bone support. The patient was a healthy teenage girl who sustained facial trauma with loss of teeth and alveolar bone. The defect was initially bone grafted. Brånemark implants were simultaneously placed in the graft. Their initial unfavorable positions and inclinations were later corrected by a segmental osteotomy.

Adolescent↗
PubMed1993

The effects of clozapine on severely aggressive psychiatric inpatients in a state hospital.

BACKGROUND: After noting a dramatic reduction in aggression and agitation in five psychotic inpatients residing on a specialized unit for the severely aggressive, the authors conducted a retrospective chart review to assess the possible role of clozapine treatment in this change. METHOD: The authors culled 12 months of nursing data, including progress notes, orders for seclusion, and mechanical and chemical restraint, to tabulate the frequency of aggression before and after the initiation of clozapine treatment, and looked at ratings on the Brief Psychiatric Rating Scale and periodic review reports to assess overall clinical change. RESULTS: The results of the review indicate that although psychotic symptoms were not greatly affected by the drug, the overall frequency of assaults, self-abuse, and the use of seclusion, mechanical restraint, and chemical restraint was reduced in the subjects. CONCLUSION: The authors conclude that because the reduction of aggression and agitation coincided with clozapine treatment, it is likely that clozapine was responsible for the change. The authors propose possible reasons for this effect and suggest that controlled studies are needed to substantiate these preliminary results.

Adult↗
PubMed1990

Effect of a denture adhesive on mandibular denture dislodgment.

The cineradiographic technique was used to assess the retention of complete mandibular dentures during chewing. The study comprised ten complete-denture wearers with severe alveolar ridge resorption in the mandible. Two cineradiographic recordings were performed, with and without a denture adhesive spread onto the base of the mandibular denture. The analysis of the cineradiographic films disclosed a significant decrease in denture dislodgment, expressed as maximal value, when a denture adhesive was used. The mean dislodgment also decreased, but not significantly.

Adhesives↗
PubMed1986

Responses of morphologically identified cortical neurons to intracellularly injected cyclic GMP.

Cyclic nucleotides are thought to act as second messengers of neurotransmission inside central neurons, and cyclic guanosine monophosphate (cGMP) has been postulated to act as a messenger for muscarinic, cholinergic transmission. Nonetheless, the action of cGMP has not yet been established in identified cortical neurons. We injected cGMP and horseradish peroxidase (HRP) intracellularly in neurons of the motor cortex of awake cats. Fifty-four percent of injected cells responded to cGMP and HRP with an increase in input resistance within 30 s after injection. None of a control group of cells injected with HRP without cGMP so responded. In cells receiving intracellular depolarizing current sufficient to produce repeated spike discharge at the time of injection, the increase in input resistance after cGMP persisted for as long as the cells could be held. There was no significant increase in firing rate after injection of cGMP. Cells responding to cGMP with an increased input resistance were identified as pyramidal cells of layer V. One inverted pyramidal cell of layer VI also showed an increase in input resistance in response to cGMP. Previous studies have suggested that muscarinic cholinergic agents produce an increased input resistance (thought to reflect a decreased potassium conductance) underlying an increased rate of discharge in neocortical neurons. Our results favor a dual action of muscarinic cholinergic transmission in mammalian cortical neurons--the increase in input resistance in layer V pyramidal cells mediated by cGMP, and the increase in rate of discharge mediated by other means.

Animals↗
PubMed1986

Malignant change in cysts of the skin.

The concept that squamous carcinoma arises with any frequency from common skin cysts is examined. We believe this to be extremely rare and suggest that many of the previously reported cases are pilar tumors or proliferating trichilemmal cysts, a benign but clinically impressive lesion occurring most commonly in the scalps of older women. An illustrative case is presented.

Carcinoma, Squamous Cell↗
PubMed1981

Denture adhesives - their effect on the mobility of full upper dentures during chewing. A cineradiographic study.

Using cineradiographic technique an assessment is made of the denture mobility during function in the upper jaw for full denture wearers without and using two types of denture adhesives. One of them with a new formula. Ten randomly selected edentulous patients with moderate alveolar ridge resorption took part in the study. They were rehabilitated with dentures of conventional design in the upper jaw. Cineradiographic registrations were performed in lateral projection without and with the two types of adhesives supplied to the denture base. The analysis of the cineradiographic films disclosed no significant differences for the denture mobility. Neither between the situation without and with denture adhesive nor between the two adhesives. This indicates an obvious limited effect of the denture adhesives, at least for denture wearers with moderate resorption of their alveolar ridges. The only positive effect of the adhesives discovered was a limited number of vertical loosening drops of the distal parts of the denture when the seal was broken.

Adhesives↗
PubMedDate not supplied

Implant-supported maxillary overdentures: outcome in planned and emergency cases.

At the Postgraduate Dental Education Center, Orebro, Sweden, maxillary implant-supported overdentures have mainly been used in either planned cases (where implants sufficient for a fixed prosthesis could not be placed) or emergency cases (originally planned for a fixed restoration but where implants lost during the healing period made such treatment impossible). Twenty-five cases were studied retrospectively. In the planned group, only two of 19 patients had lost an implant during the follow-up period with overdentures; in the emergency group, four subjects of six lost implant(s) during the same period. The total loss of implants during healing and overdenture function was 7% in the planned group and 72% in the emergency group. The curves for survival of overdentures without loss of supporting implants were significantly different (P = .00) for the planned group and the emergency group.

Adult↗
PubMedDate not supplied

Artificial crowns and fixed partial dentures 18 to 23 years after placement.

Patients receiving artificial crowns and fixed partial dentures at a prosthodontic clinic were examined 18 to 23 years after treatment. The long-term results were good, especially for the metal ceramic restorations: 79% remained unchanged and only 3% had been removed. The success rate for the gold-resin restorations was less favorable: 43% remained unchanged and 33% had been removed. The use of one cantilever extension unit had not negatively influenced the results for the fixed partial dentures. Generally, those abutment teeth that had been removed during the observation period had received previous endodontic treatment before restorations had been placed. Endodontic complications on abutment teeth were more frequent in the mandible than in the maxillae.

Adult↗
PubMedDate not supplied

Marginal bone levels around maxillary implants supporting overdentures or fixed prostheses: a comparative study using detailed narrow-beam radiographs.

The issue of changes in marginal bone levels around maxillary implants supporting overdentures has been studied very little because of radiographic difficulties when using conventional intraoral techniques. The present study used detailed narrow-beam radiography, which offers excellent opportunities to depict implants and the surrounding bone in severely resorbed maxillae. Marginal bone levels around implants in patients with overdentures were compared to corresponding bone levels in a group of matched control patients with fixed prostheses supported by osseointegrated implants. No statistically significant difference in marginal bone height was noted between the groups. This finding is not in accordance with an earlier report on continuous loss of marginal bone around many maxillary implants supporting overdentures.

Bone Resorption↗