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Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 721 records · Page 40Linked to original sources
PubMedDate not supplied

Lumbar spine and femoral neck bone mineral density in idiopathic scoliosis: a follow-up study.

A follow-up study of the bone mineral densities (BMD) of 22 female subjects with idiopathic scoliosis was performed using dual-photon absorptiometry at an average follow-up period of 30.8 months. Compared to the initial scans, statistically significant increases in lumbar spine and femoral neck BMD were observed. When compared to normal subjects, approximately half of the scoliotic subjects were markedly osteoporotic, having BMD measurements at least two standard deviations below the expected value. Scoliotic curvature data could not be correlated with the BMD data. The observed osteoporosis is not transient and appears characteristic of idiopathic scoliosis.

Absorptiometry, Photon↗
PubMedDate not supplied

An initial assessment of the optical properties of human laryngeal tissue.

The optical properties of human laryngeal tissue have been examined over the whole wavelength range from 400 to 2,200 nm to facilitate the development of new laser applications. Tissue samples were taken from healthy vocal fold and from vocal fold of patients with papillomatosis and with chronic, nonspecific laryngitis. The transmission and scattering properties of the tissue samples were recorded with a computer-guided integrating-sphere system. From the measured data the optical properties were calculated by means of the inverse Monte Carlo simulation. In the 500- to 600-nm range papilloma tissues had a considerably higher absorption than healthy vocal fold. When applying the optical tissue properties as a possible influencing factor of the effectiveness of laser systems, laser applications at this wavelength range may be useful in the ablation of papilloma tissue.

Anisotropy↗
PubMedDate not supplied

Extended high frequency audiometry in pre-school children.

Since adequate and reliable earphones are now available and standards have been established, clinical audiometry can be performed at extended high frequencies (EHFs). In the present study, 47 preschool children (aged 4-7 years) were examined with EHFs (8-16 kHz) using the new Sennheiser HDA 200 earphone. The hearing thresholds correspond to those of other studies; the median thresholds and range increase with increasing frequency. The medians and quartiles were: 10 kHz: 25 (5-35) dB(SPL), 11.2 kHz: 35 (20-40) dB(SPL), 14 kHz 40 (30-50) dB(SPL) and 16 kHz: 50 (40-60) dB(SPL). The hearing thresholds could be more reliably determined in the older children (> 5 years) and were 5 dB better than in the younger ones (< 5 years). Thresholds in the 10-12.5 kHz range correspond to those of adults but are more sensitive by 5-12 dB in the 14-16 kHz range.

Adolescent↗
PubMedDate not supplied

Sinus augmentation for single-tooth replacement in the posterior maxilla: a 3-year follow-up clinical report.

A technique for single-tooth sinus lift and simultaneous implant placement in the posterior maxilla is presented. Ten hydroxyapatite-coated cylindric implants, 13 to 15 mm in length, were placed together with a composite bone graft of demineralized freeze-dried bone allograft and autogenous bone in 10 adults. Surgical technique and anatomic considerations are discussed. Follow-up of 3 years showed successful function and no cervical bone loss in all patients.

Adult↗
PubMedDate not supplied

Microleakage at the abutment-implant interface of osseointegrated implants: a comparative study.

Microleakage can occur at the abutment-implant (A-I) interface in osseointegrated implants and may cause malodor and inflammation of peri-implant tissues. The degree of microleakage at the A-I interface of 5 implant systems was comparatively assessed at varying closing torques. Using colored tracing probes driven by a 2-atm pressure system, the interface microleakage of Brånemark, Sulzer Calcitek, 3i, ITI, and Steri-Oss implants was determined spectrophotometrically. Microleakage through the A-I interface occurred in all systems, with variability between systems, samples, and closing torques. As closing torque increased from 10 Ncm to 20 Ncm to manufacturers' recommended closing torques, microleakage decreased significantly (P < .005) for all systems. Analysis of variance showed significant interaction between closing torques and the time course of microleakage, and between systems and the time course of microleakage (P < .001). The results indicate that fluids and small molecules are capable of passing through the interface of all the A-I assemblies studied. Presumably in an in situ situation, fluids containing bacterial byproducts and nutrients required for bacterial growth may pass through the interface gap, contributing in part to clinically observed malodor and peri-implantitis.

Analysis of Variance↗
PubMedDate not supplied

Detection of Tropheryma whippelii DNA (Whipple's disease) in faeces.

To date the diagnosis of Whipple's disease is based mainly on the histopathological analysis of duodenal biopsies since Tropheryma whippelii cannot be cultured in vitro. We investigated the possibility to diagnose Whipple's disease by detection of bacterial DNA in faces. Nested polymerase chain reaction with amplification of part of the 16S rRNA gene of this bacterium in DNA extracted from faeces of a patient with Whipple's disease was performed. Sequencing of the polymerase chain reaction product revealed the sequence of Tropheryma whippelii. We conclude that Whipple's disease will be able to be diagnosed non-invasively by DNA analysis from the faeces as soon as more specific sequences of this bacteria are known.

Actinobacteria↗
PubMedDate not supplied

An investigation of heat transfer to the implant-bone interface related to exothermic heat generation during setting of autopolymerizing acrylic resins applied directly to an implant abutment.

Excessive heat generation at the implant-bone interface may cause bone damage and compromise osseointegration. Autopolymerizing acrylic resins are commonly used intraorally to join impression copings and suprastructure components for soldering. The effect of heat generation at the implant surface related to the exothermic setting reaction of autopolymerizing acrylic resins applied to an attached abutment was examined in vitro. Two brands of autopolymerizing acrylic resin, Duralay and GC Pattern Resin, were compared. Acrylic resin was applied to a titanium alloy abutment connected to a titanium alloy cylindric implant in varying controlled volumes, with both bulk application and brush paint-on techniques. The implant was embedded in an acrylic resin mandible in a 37 degrees C water bath. Temperature changes were recorded via embedded thermocouples at the cervical and apical of the implant surface. Analysis of variance for repeated measures was used to compare treatment groups. A mean maximum increase in temperature of 4 to 5 degrees C was seen at the implant cervical for both materials, with a maximum temperature increase of 6 degrees C. No difference between Duralay and GC Pattern Resin was seen, except for bulk application to medium-sized copper bands at the implant cervical (P < .05). No difference between the bulk and brush techniques was seen for all options, except for GC, where bulk application to medium-sized copper bands produced higher temperatures than the brush technique (P < .05). Spray coolant reduced temperatures for bulk application of both Duralay and GC (P < .05).

Acrylic Resins↗
PubMedDate not supplied

[Parkinson disease in neurologic general practice in Alsace-Lorraine. Characteristics and study of the treatment].

A study was performed in 220 out-patients with Parkinson's disease followed by general neurologists. The general characteristics of the patients are similar to those observed in the large epidemiological studies. The main conclusion concerns the low use of dopamine agonists. It confirms the discrepancy between drug prescription in general practice and the data from therapeutic drug trials.

Family Practice↗
PubMedDate not supplied

Comparative study of condylar settings of three semiadjustable articulators.

The reproducibility of arcon semiadjustable Whip Mix, Denar Mark II, and Hanau 158 articulators was tested using multiple protrusive and lateral edge-to-edge wax interarch registrations made with an interocclusal device. Photographic and cephalometric tracings verified an identical angulation between the axis-orbital craniofacial reference plane and the maxillary occlusal plane for the subject and both the Denar Mark II and Hanau 158 articulators. This angle was 2.5 degrees less in the Whip Mix instrument. Three operators made three settings for each of 12 protrusive and 24 lateral interarch registrations for each articulator. Results showed significant differences between instruments. Whip Mix consistently gave the highest.angulations and Hanau 158 the lowest. For protrusive records there was no significant difference between examiners, but for lateral records a significant difference in examiner registration was found. For both protrusive and nonworking registrations, interaction was seen between instrument and operator and between instrument and registration, and a significant difference was seen between records. This study supports previous studies showing that semiadjustable articulators using interarch records have a low level of reproducibility and are subject to variables of instrument, operator, and occlusal records.

Adult↗
PubMedDate not supplied

[Quantitative analysis of corneal excisions using argon fluoride excimer laser (193 nanometers)].

Excimer lasers represent a new and distinctive class of laser-tissue interaction termed photoablation. They can ablate materials with a high degree of precision and minimal damage to surrounding structures. The argon Fluoride excimer laser, which offers the possibility of non-contact corneal cutting, has a potential for clinical application of keratorefractive surgery. Since each pulse of excimer laser etches some amounts of tissue from the cornea, the repetitive pulses focused to a narrow line can create linear excisions. In this study, a quantitative analysis of both depth and width of corneal excisions was made on cadaver eyes at a given fluence (600 mj/cm2) and a constant repetitive rate (20Hz). The amount of ablation per pulse was not constant and the excisional depth did not show a linear correlation with pulse numbers. Both the depth and width of transversal excisions were more homogenous than those of radial excisions along the entire length of ablation.

Cornea↗
PubMedDate not supplied

Myopic keratomileusis by excimer laser on a lathe.

BACKGROUND: We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone. METHODS: A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses. RESULTS: Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34. CONCLUSIONS: The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

Animals↗
PubMedDate not supplied

An investigation on heat transfer to the implant-bone interface due to abutment preparation with high-speed cutting instruments.

Excessive heat generation at the implant-bone interface may cause irreversible bone damage and loss of osseointegration. The effect of heat generation in vitro at the implant surface caused by abutment reduction with medium- and extra-fine-grain diamond and tungsten burs in a high-speed dental turbine was examined. Titanium-alloy abutments connected to a titanium-alloy cylindrical implant embedded in an acrylic-resin mandible in a 37 degrees C water bath were reduced horizontally and vertically. Temperature changes were recorded via embedded thermocouples at the cervix and apex of the implant surface. Analysis of variance for repeated measures was used to compare seven treatment groups. Thirty seconds of continuous cutting with standard turbine coolant caused a mean temperature increase of 1 degrees C with a maximum of 2 degrees C. Similar tungsten cutting caused a mean increase of 2 degrees C with a maximum of 4.7 degrees C, significantly higher than diamond reduction. Additional air-water spray for continuous tungsten cutting had no significant effect, while intermittent cutting for 15-second increments reduced the temperature increase by 75%. Thus, abutment reduction with medium-grit diamonds using intermittent pressure and normal turbine coolant is unlikely to cause an interface-temperature increase sufficient to cause irreversible bone damage and compromise osseointegration.

Acrylic Resins↗
PubMedDate not supplied

The use of sumatriptan in the treatment of migraine.

Sumatriptan is a selective agonist of 5-hydroxytryptamine receptors, recommended for the acute treatment of migraine. The 5-HT1 receptor subtype is found in the cranial vasculature of many species including humans, and causes vasoconstriction of these vessels. Sumatriptan as a highly potent 5-HT1 agonist selectively constricts large intracranial blood vessels and also blocks neurogenic inflammation. Those treating patients with severe or inconveniently timed attacks will find sumatriptan the drug of choice.

Humans↗