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Biomedical subjects

M H Walter

Publications and source records attributed to M H Walter.

14 recordsLinked to original sources
PubMed1992

Computer-aided evaluation of occlusal load in complete dentures.

A computerized diagnostic system was tested for its capability to evaluate the occlusal equilibrium of complete dentures. Its electronic sensor foil was calibrated to intraorally compute a load index for the left and right sides of the denture. The index is calculated by the measured force and number of occlusal contacts. Perfect equilibrium is given by a ratio of load left-to-load right of 1:1. Centric occlusion of complete dentures was examined before and after remounting. A good correlation between load index and the occlusal relationship on the articulator could be observed. The system appears to be suitable for verifying the need for occlusal adjustment. However, improvements concerning the hardware and software are necessary.

Bite Force↗
PubMed1992

Non-cast titanium restorations in fixed prosthodontics.

The problems encountered in casting titanium in dentistry have not been completely resolved. The Procera system forms crowns by means of a combination of spark-erosion and milling. The accuracy of fit was examined before and after ceramic veneering both in vitro and in vivo. Before veneering, on conical surfaces space widths were approximately 53 microns in vitro and 69 microns in vivo. At shoulders and occlusal surfaces, spaces of about 430 microns were measured in vitro and of about 500 microns were measured in vivo. After ceramic veneering, slight increases in space widths could be observed. The metal-ceramic compound was tested by the 3-point bending test (DIN) and the bending test (ISO). The DIN test was satisfactory, but not the ISO test. It is concluded that titanium crowns processed by the Procera System are suitable for clinical usage, if the space widths at shoulders and the occlusal surface and the special requirements of tooth preparation are taken into account.

Ceramics↗
PubMed1990

Crystallization of tuna ferricytochrome c at low ionic strength.

Previous crystallographic studies of tuna ferricytochrome c have employed crystals grown from solutions of ammonium sulfate, corresponding to an ionic strength of 9.5 M (Takano, T., and Dickerson, R. E. (1981) J. Mol. Biol. 153, 95-115). To obtain a structure at a lower ionic strength, the ferric tuna protein was crystallized at neutral pH with polyethylene glycol at an ionic strength of 45 mM, These crystals (space group P2(1), a = 37.11 A, b = 107.66 A, c = 55.75 A, beta = 105.3 degrees) contain four molecules/asymmetric unit and grow to dimensions of 0.2 X 0.4 X 1.0 mm in 2-4 weeks. They diffract to beyond 1.8 A and are stable in the x-ray beam. We have recorded 28,198 unique Bragg reflections (83% of those possible) to a resolution of 1.89 A from a native crystal. We are undertaking a solution of this structure by the molecular replacement method.

Animals↗
PubMed1990

Bean pathogenesis-related (PR) proteins deduced from elicitor-induced transcripts are members of a ubiquitous new class of conserved PR proteins including pollen allergens.

We have searched for induced transcripts in a cDNA library derived from bean cell supension cultures treated with an elicitor from Colletotrichum lindemuthianum. Six independently isolated cDNAs corresponding to rapidly induced small mRNAs have been classified by their DNA sequence and slightly different induction behaviour into two groups. 5'- and 3'-untranslated regions exhibit little similarity, but the deduced small acidic proteins designated PvPR1 and PvPR2 are 89% identical. No relationship was found with the well-characterized PR1 proteins from tobacco. However, the PvPR proteins are closely related to pI49 in pea (64% identity), pSTH2 in potato (41% identity) and PcPR1-1 in parsley (39% identity), which are also induced in response to elicitor or microbial attack. Moreover, a major pollen allergen in birch (BetvI) has a 44% identity with PvPR1 proteins. These similarities establish a ubiquitous class of conserved defense-related proteins and suggest a common yet still unknown function. Southern blot analysis indicates that PvPR protein gene organization is highly complex with an estimated copy number of more than 12 genes.

Amino Acid Sequence↗
PubMed1990

Steady-state infusions of opioids in human. II. Concentration-effect relationships and therapeutic margins.

We used computer-controlled individually tailored infusions to study relationships between plasma drug concentration and opioid effects, and to evaluate the therapeutic margins of alfentanil, fentanyl and morphine in human subjects. In order to compare the 3 drugs, we infused each opioid to 3 different steady-state target plasma concentrations during separate 8 h test periods so that concentration-effect curves could be defined for each opioid and subject. Dental electrical stimulation produced a consistent degree of baseline experimental pain, and we measured the influence of increasing plasma opioid concentrations on pain intensity and the magnitude of pain-related evoked potentials. We also quantified ventilatory function and subjective side-effects during baseline (no drug), at the 3 target plasma concentrations with each drug. Finally, we measured actual plasma opioid concentrations during each phase of the infusion period. This procedure allowed us to calculate for each opioid the plasma concentration required to produce a 50% decrease in reported pain intensity and evoked potential amplitude (IC50). Subsequent calculation of side-effect magnitudes at the analgesic IC50s permitted direct comparisons of therapeutic margins between alfentanil, fentanyl and morphine. We found a robust relationship between plasma drug concentration and analgesic, ventilatory, and subjective-effect magnitudes for each opioid in this study. We conclude that the magnitudes of individual side-effects associated with equianalgesic, steady-state plasma concentrations of these 3 mu receptor-selective opioids do not differ across drugs.

Adult↗
PubMed1990

[The multidisciplinary outpatient pain clinic in relation to anesthesia. An important task for the anesthesiologist].

Anesthesiologists have always played a leading role in research into pain and its treatment. Their efforts, however, have been focused on acute or postoperative pain problems. It was the American anesthesiologist John J. Bonica who fought for an increased interest in chronic pain. The establishment of the first Multidisciplinary Pain Center at the University of Washington in Seattle, the foundation of the International Association for the Study of Pain (IASP) and Melzack and Wall's now 25 year old gate control theory were the driving forces behind rapid developments in research and treatment in the area of chronic pain. The realization that chronic pain was the most frequent cause of disability in the United States also gave an impetus for new efforts in treatment. The classic anesthesiological topics, such as operative anesthesia emergency medicine and intensive care, have been extended to include acute pain services and chronic pain treatment facilities. This reflects the understanding that anesthesiological knowledge and techniques can be valuable to patients in severe acute pain and those in lingering long-term chronic pain phases. Anesthesiologists are skilled in the use of opioid narcotics and in the administration of strong analgesics. Many severe pain problems can be solved by correct use of the analgesic regimen. Special ways of administering narcotic analgesics, such as epidural infusion or patient-controlled analgesia, have already alleviated the pain problems of many patients. Anesthesiological techniques are also crucial in diagnosis. Sequential differential blockade and simple nerve blocks can be helpful in the diagnosis and classification of the pain problems. Anesthesiological contributions to a chronic pain service are not restricted to medical interventions. Organizational skills are also needed for efficient running of multidisciplinary pain treatment facilities. Clinical practice in surgical anesthesia means that anesthesiologists are experienced in interdisciplinary work and familiar with the advantages and dangers of team work. Despite international acceptance of the multidisciplinary approach to chronic pain, there is still a lack of appropriate facilities in the German-speaking countries, and we consider it important that anesthesiologists commit themselves to increasing general awareness of what is needed.

Ambulatory Care Facilities↗
PubMed1988

Cinnamyl-alcohol dehydrogenase, a molecular marker specific for lignin synthesis: cDNA cloning and mRNA induction by fungal elicitor.

Cinnamyl-alcohol dehydrogenase (CAD; EC 1.1.1.195) catalyzes the final step in a branch of phenylpropanoid synthesis specific for production of lignin monomers. We have isolated a full-length cDNA clone encoding CAD, as a molecular marker specific for lignification, by immunoscreening a lambda gt11 library containing cDNAs complementary to mRNA from elicitor-treated cell cultures of bean (Phaseolus vulgaris L.). The clone comprises a single long open reading frame of 1767 base pairs, 31 base pairs of 5' leader, and 152 base pairs of 3' untranslated sequence. The deduced 65-kDa CAD polypeptide has several features that are strongly conserved in alcohol dehydrogenases. Addition of fungal elicitor to cell cultures stimulates CAD transcription, which leads to a remarkably rapid, but transient, accumulation of CAD mRNA, with no detectable lag and maximal levels after 1.5 hr. Southern blot analysis of bean genomic DNA indicates that elicitor-induced CAD is encoded by a single gene. The regulatory significance of the rapid activation of this CAD gene and the possible existence of a second, divergent CAD gene involved in lignification during xylogenesis are discussed.

Alcohol Oxidoreductases↗
PubMed1986

Dose effects of alfentanil in human analgesia.

Alfentanil, a rapidly acting opioid, was given in subanesthetic doses to 10 subjects in a laboratory setting. Analgesia was assessed from the subjects' responses to painful dental stimulation. A subjective pain report (PR) and brain evoked potential (EP) amplitude were obtained repeatedly before and after injection on each of 4 testing days, on which the following intravenous doses were administered: 0 (saline solution), 5, 10, and 15 micrograms/kg. Significant dose effects were observed for EP amplitude during but not beyond the distributional t1/2 of the drug, but significant effects on the PR extended beyond this time point. Mean volume of distribution, total body clearance, and distribution t1/2 did not differ significantly across the doses of alfentanil. Strong correlations between each effect measure and plasma drug concentration were observed at all doses and were significant at P less than 0.01. The EP scores tracked the distribution of alfentanil very closely, but the correlation between EP amplitude and plasma alfentanil concentration was lower during the elimination phase. In contrast, the PR effects closely tracked the elimination of alfentanil but not its distribution. These findings suggest that EP amplitude and the PR represent two different central effects in opioid analgesia.

Adult↗
PubMed1986

"Dermodress", a new temporary skin substitute: pilot study on donor sites.

"Dermodress" is a new temporary biological dressing (heterograft) composed of a pure neonatal bovine collagen I. The authors present their first trial with this skin substitute. Ten consecutive patients who required skin grafts were included in the pilot test group. The "Dermodress" was tested on their donor sites and compared with "Furacin" gauze. It was found that "Dermodress" provided a covering that adhered excellently to debrided surfaces, without disturbing the healing processes underneath, for up to three weeks after application. The results point to the potential value of the "Dermodress" for open wounds.

Adolescent↗
PubMed1985

Dermodress: a new, temporary skin substitute for extensive deep burn coverage.

A chemically treated bovine skin, Dermodress, is presented as a long-term skin substitute. Dermodress was applied over denuded surfaces of debrided deep burns and was kept in place for up to 56 days. Dermodress adheres to all contours of the debrided surfaces, has hemostatic effect and does not present any signs of infection or rejection. Dermodress can be removed in stages according to the availability of autografts, which may be applied immediately, since the exposed areas are clean and suitable for immediate grafting. Our clinical experience shows that Dermodress has most of the required properties of a long-term temporary skin substitute.

Adolescent↗
PubMedDate not supplied

Addition of enemas to oral lavage preparation for colonoscopy is not necessary.

To evaluate whether the addition of enemas to oral electrolyte lavage is helpful for colonoscopic preparation, we conducted a prospective, randomized, observer-blinded trial to compare oral lavage plus enemas with oral lavage alone. The quality of preparation, mucosal visualization, and the volume of retained colonic fluid did not differ between the two groups. Twenty-two percent of the patients in the group who received oral lavage plus enemas compared with 12% of the patients in the group that only received oral lavage stated that they would refuse to repeat the preparation for future colonoscopic examination. Seventeen percent of the patients in the group that received oral lavage plus enemas demonstrated anorectal trauma or inflammation compared with only 5% in the group that received oral lavage alone (p = 0.09). These results indicate that the addition of enemas to oral lavage preparation for colonoscopic evaluation cannot be routinely recommended. However, enemas may be considered on an individual basis in the occasional patient unable to consume the complete oral lavage or in whom residual stool is found during colonoscopic evaluation after oral lavage preparation.

Colonoscopy↗