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Biomedical subjects

E Berg

Publications and source records attributed to E Berg.

At least 19 recordsLinked to original sources

A method for testing denture adhesives.

An in vitro test is described that simulates the in vivo fate of a denture adhesive, namely destruction, dilution, and dissolution of the adhesive, by repeated measurement of tensile bond strength for the adhesive in isotonic saline over time. The bond strengths were measured under two different settings of the testing machine. The main compositions of three denture adhesive pastes, Fittydent, Fixodent, and Super Poli-Grip and one powder adhesive, Super Wernet's, were determined by infrared spectroscopy. The tensile bond strengths of these adhesives and those of pure tragacanth gum were subjected to a three-way analysis of variance. The Fittydent and Super Poli-Grip adhesives exhibited the best results over time. The most appropriate of the described methods for testing denture adhesives seem useful; however, when seen in relation to the results of a published clinical study where the patients were asked to evaluate the retention and the duration of some of these adhesives, there are indications that the clinical validity of the method might be improved if paste adhesives are tested at temperatures above 35 degrees C.

Adhesives

Mechanical properties of laser-welded cast and wrought titanium.

This study evaluated the mechanical properties of laser-welded cast and wrought titanium base and compared them with those of a brazed type IV casting gold alloy. Ultimate tensile strength, 0.2% yield strength, and percent elongation were recorded for joined and unjoined bars of the previously mentioned materials. Sections of titanium bars were laser-welded, and gold alloy bars were brazed. Both joining methods significantly reduced the ductility of the material. The strength of the cast gold alloy was superior to that of titanium. However, the strength of the laser-welded titanium equaled that of the brazed gold alloy, which suggests that dental restorations made of cast and wrought titanium would satisfy ordinary clinical requirements.

Analysis of Variance

A non-electrostatic spacer for aerosol delivery.

A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide pressurised metered dose inhaler (p-MDI) to minimise the electrostatic charge on the plastic. The procedure prolonged the half life (t1/2) of the aerosol in the Nebuhaler from nine to 32 seconds. A normal cleaning procedure reduced the aerosol t1/2 back to baseline. The t1/2 of the aerosol in the metal spacer was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 45% from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months to 6 years, suspected to have asthma the non-electrostatic spacer delivered a mean total dose of budesonide aerosol of 39% of the nominal dose, which was significantly higher than the Babyhaler (28%), the Nebuhaler (21%), and the AeroChamber (19%). These differences were most pronounced in children younger than 4 years. The improved dose delivery from the small volume non-electrostatic spacer is probably related to the non-electrostatic spacer material and the valves which assured unidirectional airflow from the spacer without adding any dead space in the inspiratory channel. The non-electro-static spacer should improve the cost effectiveness of aerosol treatment and, as the counteracting effects of proming and recharging of the plastic from cleaning are avoided, should deliver a more reliable dose.

Aerosols

Manual therapy with steroid injections--a new approach to treatment of low back pain. A controlled multicenter trial with an evaluation by orthopedic surgeons.

Fifty-three acute or subacute patients with low back pain were given standardized but optimized activating conventional treatment by primary health care teams. Forty-eight patients received an experimental treatment that included specific manual treatment, such as manipulation and specific mobilization, muscle stretching, auto-traction, and cortisone injections. After 4 months, the experimental group had a less restricted range of movement in extension, less restricted side-bending to the right and to the left, less local pain caused by extension and side-bending to the right, less pain radiating to the right leg caused by side-bending to the left, and a less positive straight leg raising test (both sides) than the conventionally treated group. Manual treatment was superior to the conventional activating treatment in normalizing pathologic findings on physical examination of the lower back. These results agree with the positive influence on pain, drug consumption, sick-leave, disability rating, and quality of life reported in other reports from the same study.

Adult

In vivo characterization of the inflammatory properties of poly(tetrafluoroethylene) particulates.

Suburothelial injections of particulate poly(tetrafluoroethylene) (PTFE) is becoming a widely accepted treatment for a number of urological disorders. Because little is known about the long-term histologic morphology of the injection site, this animal study was performed. Three populations, each consisting of two mongrel dogs, five New Zealand White rabbits, and 10 BALB/c mice, were injected with poly(tetrafluoroethylene) particulate in a glycerine carrier (Polytef Paste) and were followed for a period of 1 week, 3 months, 6 months, and 1 year. Mice received one subcutaneous dorsal injection each, rabbits received two subareolar injections each, and dogs received three subareolar injections each in addition to two periurethral injections. Histologic examination of the biopsy sites revealed a persistent chronic inflammatory reaction with progressive growth of the involved tissue volume. In addition to giant cells and macrophages, lymphocytes became apparent at 3 months and constituted up to 40% of the cellular infiltrate by 1 year. Plasma cells were also noted at the 1-year period in the rabbit model. The progressive growth of the inflammatory pseudo-tumors evoked by injected PTFE may compromise the long-term safety of certain urological procedures involving particulate PTFE.

Acute Disease

Auranofin treatment in early rheumatoid arthritis may postpone early retirement. Results from a 2-year double blind trial.

The effect of early vs delayed initiation of slow acting antirheumatic drug (SAARD) therapy on the ability to maintain regular work, was evaluated in 83 patients with early rheumatoid arthritis (RA) in a placebo controlled, double blind 24-month study. The estimated probability to maintain working ability was higher in the early treatment group, especially during the second study year. Predicting factors were age, type of work, degree of disability and number of swollen joints. Despite the difficulties in interpreting the results due to the complexity of the underlying socioeconomical and labor market situation, the study supports early treatment in RA with regard to the maintenance of normal life.

Arthritis, Rheumatoid

Time-dependent modifications of ferric-adriamycin.

The biological and chemical properties of the ferric-Adriamycin complex changed with time after its preparation. Our experiments demonstrated that the toxicity of the iron-chelate in mice decreased as a function of its age. The reduced toxicity can be correlated with changes in the difference spectrum of ferric-Adriamycin vs Adriamycin (ADR), where a peak around 610 nm shifted to the 570 nm region. When ferric-Adriamycin "aged", the affinity of the drug for iron increased. Concurrently, the redox properties of the chelate changed, such that the bound iron was no longer reduced by glutathione or cysteine. The time-dependent changes observed did not involve the formation of polynuclear iron, as shown by electron spin resonance. Thin-layer chromatography showed that ADR undergoes accelerated degradation in the presence of iron. The iron-catalyzed degradation was oxygen independent. The changes evolving in the spectral and chemical properties of the chelate were shown to stem from transfer of the iron from ADR to one of the degradation products.

Anaerobiosis

Primary structure and glycosylation of the S-layer protein of Haloferax volcanii.

The outer surface of the archaebacterium Haloferax volcanii (formerly named Halobacterium volcanii) is covered with a hexagonally packed surface (S) layer. The gene coding for the S-layer protein was cloned and sequenced. The mature polypeptide is composed of 794 amino acids and is preceded by a typical signal sequence of 34 amino acid residues. A highly hydrophobic stretch of 20 amino acids at the C-terminal end probably serves as a transmembrane domain. Clusters of threonine residues are located adjacent to this membrane anchor. The S-layer protein is a glycoprotein containing both N- and O-glycosidic bonds. Glucosyl-(1----2)-galactose disaccharides are linked to threonine residues. The primary structure and the glycosylation pattern of the S-layer glycoproteins from Haloferax volcanii and from Halobacterium halobium were compared and found to exhibit distinct differences, despite the fact that three-dimensional reconstructions from electron micrographs revealed no structural differences at least to the 2.5-nm level attained so far (M. Kessel, I. Wildhaber, S. Cohe, and W. Baumeister, EMBO J. 7:1549-1554, 1988).

Amino Acid Sequence

Animal model for evaluating bone repair with and without adjunctive hyperbaric oxygen therapy (HBO): comparing dose schedules.

The effect of hyperbaric oxygen (HBO) on the healing of standardized metaphyseal defects in the cortices of rat femurs was studied. The question was whether a known total amount of HBO given twice a day (BID) would have a different effect than once a day (QD) treatments. A microvascular casting technique was developed whereby vessel ingrowth at the repair site could be monitored using scanning electron microscopy (SEM). Bone repair morphology was evaluated by light microscopy (LM) and various tissue components were quantified by histomorphometry (HM). Animals were sacrificed 1, 2, 3, or 5 weeks postoperatively. SEM revealed that endosteal bone ingrowth was totally responsible for the repair of the cortical defects. Moreover, endosteal vessel ingrowth did not differ between controls and either group of HBO treated animals. LM displayed enchondral ossification in controls and BID treated animals and a pronounced osteoclastic activity in the latter group throughout the repair process. By contrast the QD treated group healed by primary ossification. Judged by the HM data, QD treatment appeared to accelerate bone repair and vessel ingrowth compared to controls, while BID treatment seemed to retard these processes.

Animals

Auranofin (SK&F) in early rheumatoid arthritis: results from a 24-month double-blind, placebo-controlled study. Effect on clinical and biochemical assessments.

In a 2-year, randomized, double-blind Nordic multicentre trial, auranofin was compared with placebo in early (disease duration less than or equal to 2 years), active rheumatoid arthritis (RA). Efficacy and safety were analysed in 67 patients receiving auranofin and 65 receiving placebo. Life table analysis demonstrated a significantly higher withdrawal rate due to insufficient therapeutic effect in the placebo group, whereas more patients dropped out due to side effects in the auranofin group. More auranofin than placebo patients (35 vs. 24) completed the 2 years. Clinical and inflammatory activity improved in both groups, but consistently more so in the auranofin group, in spite of the greater consumption of local steroids and NSAIDs in the placebo group. The most frequent side effects leading to withdrawal in the auranofin group were cutaneous and gastrointestinal reactions. The study demonstrated that most patients exhibit improvement in clinical signs and symptoms and about half of all patients with early RA continue to take auranofin for at least 2 years.

Anti-Inflammatory Agents, Non-Steroidal

The use of adjunctive hyperbaric oxygen in treatment of orthopedic infections and problem wounds: an overview and case reports.

We summarize indications, contraindications, and therapeutic guidelines for the use of adjunctive hyperbaric oxygen therapy (HBO) in problem wounds and selected orthopaedic infections. Three typical cases that all were successfully treated with HBO are presented: a chronic osteomyelitis which was a sequela to an open tibia fracture, a second- and third-degree burn injury of the entire lower extremity, and a case of chronic osteomyelitis in an insulin-dependent diabetic.

Adult