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Biomedical subjects

R Schwartz

Publications and source records attributed to R Schwartz.

At least 163 records · Page 9Linked to original sources
PubMed1991

Orthopedic splint diagnostic system and fabrication.

This chapter presents a method of measuring casts in a scientifically duplicatable manner, using the orthopedic relator to diagnose the plane of occlusion. This allows the practitioner to determine if occlusal equilibration is a viable treatment modality for a particular patient. For patients who do not meet the criteria for occlusal equilibration, a detailed technique for correcting the occlusal plane discrepancies through use of the orthopedic splint is presented.

Dental Articulators↗
PubMed1991

Delayed cementation and bond strength of dual-cure cements.

The purpose of this study was to determine whether the shear bond strength to enamel of three dual-cure resin cements is affected by delaying the time between cement mix and application. Etched, silanated Dicor cylinders were bonded to etched enamel with each cement at various time intervals: Immediately after mix, just prior to chemical set and at an intermediate time. Shear bond values were determined using the Instron. No significant differences were found among any of the cements at any of the times. The clinical implication is that as long as these cements remain fluid, there will not be a significant change in the bond strength of Dicor to enamel.

Acrylic Resins↗
PubMed1991

[Clinical and experimental results with a new fully automatic self-tonometer].

In a clinical study 25 patients being treated at the Department of Ophthalmology in the Hamburg University were instructed in self-tonometry using a new automatic tonometer. In a first sequence, three self-measurements were taken by the patients within 1 min; then a control measurement with a motor-driven hand applanation tonometer (HAT) was taken by a physician. The procedure was repeated 6-10 min afterwards without new local anesthesia. In addition, a dynamometer was applied to 5 healthy eyes in order to test the self-tonometer at higher pressure levels. The correlation of repetitive measurements of the self-tonometer showed good results for the patient measurements (r1 = 0.97, SD1 = 1.66 mmHg, r2 = 0.96, SD2 = 1.47 mmHg) and slightly worse values for the measurements with the dynamometer (r3 = 0.97, SD3 = 2.02 mmHg), probably due to the non-physiological deformation of the eye induced by the dynamometer. To establish accuracy, the results were compared to the HAT. The following results were achieved: (r1 = 0.97, s1 = 1.71 mmHg, r2 = 0.96, s2 = 1.49 mmHg, r3 = 0.97, s3 = 2.69 mmHg). Other studies with the self-tonometer will follow in order to optimize its accuracy and design. Self-tonometry under conditions of microgravity is planned for the 2nd German Spacelab Mission and the Russian Space station MIR. In the future, self-tonometry will play an important part in the management of glaucoma.

Animals↗
PubMed1991

Infection control in the dental laboratory: a review of the literature.

The dental laboratory has been shown to be an area of potential disease transmission between patients and to laboratory personnel. This paper reviews pertinent literature on the subject and describes the "Barrier System," a proven infection control protocol to manage dental prostheses in the laboratory.

Communicable Disease Control↗
PubMed1990

Direct relationship of antepartum glucose control and fetal erythropoietin in human type 1 (insulin-dependent) diabetic pregnancy.

In the present study the antepartum relationship between maternal diabetic glucose control and fetal hypoxaemia was examined in 44 Type 1 (insulin-dependent) diabetic and 23 non-diabetic control pregnancies. Maternal HbA1C was used to assess maternal integrated blood glucose control while fetal metabolic control was evaluated by antepartum glucose, insulin, and C-peptide determinations in amniotic fluid at elective caesarean delivery. Fetal hypoxaemia was assessed indirectly by fetal umbilical vein plasma erythropoietin level at delivery. A prospectively developed statistical pathway model was used to examine the relationship of these variables. In applying forced stepwise multiple regression with this model, we observed in the diabetic subjects that mean maternal HbA1C during the last month of pregnancy correlated significantly with fetal umbilical venous erythropoietin at delivery (r = 0.57, p less than 0.001). Additional significant contributions to umbilical venous erythropoietin were found for amniotic fluid glucose and amniotic fluid insulin when these two independent variables were added in stepwise fashion (p less than 0.01). We conclude that in diabetic pregnancy, antepartum control of maternal hyperglycaemia is a significant factor associated with fetal hypoxaemia. We speculate that this effect is mediated through perturbations which accelerate fetal metabolism and which is expressed by amniotic fluid levels of glucose and insulin.

Amniotic Fluid↗
PubMed1990

Word fluency generation skills of head-injured patients in an acute trauma center.

Two hundred-eighteen acutely brain-injured trauma patients with confirmed diagnosis of initial closed head injury completed two types of word fluency generation tasks, animal naming and single-letter-based word generation. Numbers of responses and inferred strategy utilizations were examined and compared with established norms for non-brain-injured individuals using frequency counts and chi 2 analyses. Significant differences were noted in response quantity and quality between closed head-injury patients and normals. A positive relationship was noted between level of cognitive functioning and number of word associates generated. Same initial consonant-vowel syllable (see-seed), semantic association (ship-sail), and same initial consonant-consonant blend (tree-trick) strategies were used by all subjects regardless of severity of injury. Quantitative and qualitative differences were noted as a function of severity of cognitive disruption.

Adolescent↗
PubMed1990

Safe storage times for sterile dental packs.

Safe storage times were evaluated for three sterile packaging materials that are commonly used in dentistry. No significant differences were found among packaging materials. Only three packs of 300 produced positive cultures during the 1-year test period. There were no time-related trends. The contamination levels found were within the range that has been reported to occur as a result of inadvertent contamination during unpackaging and transfer of sterile instruments. The findings of this study support the proposal that contamination is event related, not time related; that is, sterile instrument packs remain sterile for at least 1 year unless a specific event causes contamination.

Dental Instruments↗
PubMed1990

Effect of changes in the relationship of the mandible to the maxilla on the dimensions of the external acoustic meatus.

A preliminary study of seven randomly selected subjects was initiated to assay if any changes occur in body posture and in the dimensions of the external acoustic meatus when the relationship of the mandible to the maxilla is changed. The anatomic configurations presented by body posture and the external acoustic meatus, when the mandible was in a position of intercuspation, were used as points of reference. The dimensions of body posture and the external acoustic meatus were recorded for all subjects, when their respective mandibles were in intercuspation, protrusive, retrusive, as well as a position produced by orthopedic splints. Although, the position of intercuspation was used as a point of reference, comparisons of results obtained by all positions used, were made. Changes in the dimensions of body posture and the dimensions of the external auditory meatus were noted with every one of the prescribed alterations of mandibular posture.

Dental Occlusion↗
PubMed1990

Randomized, double-blind trial of cefonicid and nafcillin in the treatment of skin and skin structure infections.

We compared treatment with one daily intravenous dose of cefonicid and multidose nafcillin in 65 patients with severe infections of the skin or skin structure. Clinical cure or improvement was achieved in 91% of the patients given cefonicid and in 87% of the patients given nafcillin (P = 0.97). The use of cefonicid may allow outpatient therapy of some severe infections.

Adolescent↗
PubMed1990

Impaired insulin secretion in the neonatal rhesus monkey after chronic hyperinsulinemia in utero.

The secretion of insulin by the pancreas of the newborn rhesus monkey that had been made experimentally hyperinsulinemic in utero was studied in 18 animals. Chronic in utero hyperinsulinemia was produced by the continuous subcutaneous delivery of 4.75 units of insulin per day for 18 +/- 1 days. After delivery, the insulin-containing pump was removed to allow neonatal insulin levels to drop to normal levels. By 6.5 +/- 1.0 hr after pump removal, plasma glucose, insulin, and C-peptide immunoreactivity (CPIR) were comparable in the control and experimental animals. At that point 300 micrograms of glucagon/kg body weight was given iv to stimulate insulin secretion. After 30 min a significant elevation (expressed as the percentage of basal levels) in plasma glucose by 250%, insulin by 200%, and CPIR by 200% was observed in the control animals. In contrast, no changes in plasma insulin or CPIR concentrations occurred, with an attenuated glucose response that was only one-fifth of the control response, in the experimental animals. These results along with the observed lowered concentrations of CPIR in the plasma and insulin in the pancreas at birth can be interpreted as evidence that insulin is an inhibitor of its synthesis and secretion in utero and that this abnormal intrauterine environment causes changes that persist into extrauterine life.

Animals↗