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Biomedical subjects

L R Thompson

Publications and source records attributed to L R Thompson.

At least 19 recordsLinked to original sources
PubMed1994

Prenatal drug use in Minneapolis-St Paul, Minn. A 4-year trend.

OBJECTIVES: To determine the rates of maternal ingestion of cocaine, marijuana, and opiates in women from Minneapolis-St Paul, Minn, in 1993 and compare them with rates observed in 1989; and to compare outcomes of newborns born to those women with and without evidence of prenatal drug ingestion. STUDY DESIGN: The meconium from newborns of a representative cluster-based sample of women from Minneapolis-St Paul was analyzed for metabolites of cocaine, marijuana, and opiates. The newborns were consecutive births in four urban and suburban hospitals. Maternal demographic information and newborn outcome data were collected and matched to the meconium samples. The race, age, and socioeconomic status of the mothers whose newborns were screened were the same as the demographic characteristics of all women delivering babies in Minneapolis-St Paul in 1990 and 1991. SETTING: Metropolitan hospitals of Minneapolis-St Paul. MAIN RESULTS: Of the 1333 samples, 27 (2.0%) were cocaine positive, 35 (2.6%) were tetrahydrocannabinol positive, and 16 (1.2%) were opiate positive. There were 168 women (22.6%) reporting that they smoked. Detection of tetrahydrocannabinol and cocaine was more common in newborns of women of color, those receiving medical assistance, and those over age 23 years. Newborns with meconium samples positive for cocaine or tetrahydrocannabinol had slightly lower average birth weights but were no more likely to be premature or to require neonatal intensive care unit admission than newborns with no drugs detected in their meconium. Newborns of mothers who smoked throughout pregnancy had lower average birth weights and higher rates of prematurity and neonatal intensive care unit admissions. Standardized rates of cocaine detection in the four hospitals decreased from 4.0% in 1989 to 2.0% in 1993. CONCLUSIONS: Rates of perinatal cocaine detection have declined in the Twin Cities of Minneapolis-St Paul over the past 4 years. In this population, self-reported smoking was associated with more serious adverse outcomes of the newborns than was the detection of cocaine, marijuana, or opiates.

Adolescent↗
PubMed1985

The prevalence of the ocular side effects of chlorpromazine in the Tuscaloosa Veterans Administration patient population.

Ninety-five patients were examined between the ages of 25 and 74 years of age at the Tuscaloosa Veterans Administration Hospital and the University of Alabama at Birmingham School of Optometry. Of the 95 patients 54.7% had never taken chlorpromazine and 45.3% were taking chlorpromazine. We analyzed the prevalence of ocular side effects of chlorpromazine and found that the most prevalent side effect was anterior lens capsule dusting followed by corneal stromal pigment dusting. Both of these changes occurred at a lower cumulative dosage level than had previously been reported. The prevalence of anterior corneal epithelial opacification, anterior corneal staining, cataracts, and pigment in the macula is also reported.

Adult↗
PubMed1984

In vivo studies on the carcinogenic potential of an orthodontic bonding resin.

Data from another laboratory have indicated that the individual components of an orthodontic bonding resin might contain a carcinogen. Since that report, the formulation of the product was changed. The purpose of this study was to determine whether the new product is safe. Three groups of rats were used for the experiment. One group served as a control, while the other groups ingested the sealant resin or sealant catalyst. The materials were suspended in an alcohol-aqueous mixture and the solutions were given to the animals as their only source of fluid. The exposure was for 1 year. After this period of time, all the rats were given tap water and observed until day 600. The animals were autopsied at time of death or at the end of the experiment. During the treatment, there were significant differences (p less than 0.01) in water intake among the three groups. The average intake per day for the animals in the control group, the resin group, and the catalyst group was 50.2 cc, 37.8 cc, and 42.2 cc, respectively. Several animals died during the experiment, but there was no significant differences in the life expectancy of the animals in the three groups. The autopsies uncovered one malignant neoplasm, an undifferentiated sarcoma, in a rat from the control group and four benign tumors in rats from the three groups. All of these results indicate that the new formulation of the orthodontic bonding resin is not carcinogenic when ingested at a dose level of 50 ppm.

Animals↗
PubMed1983

Validation of a whole blood method for cholinesterase monitoring.

Traditional cholinesterase monitoring methods requiring several milliliters of blood are too invasive for prolonged routine monitoring. After several years' experience with a whole blood method requiring only 50 microL of blood for each test, a statistical evaluation of 1 year's monitoring data was undertaken to determine the normal variation of the test procedures. The results showed excellent sensitivity and reproducibility. On the basis of these data and other obvious advantages, this method is recommended as a more acceptable procedure for cholinesterase monitoring in field situations as well as plant settings.

Analysis of Variance↗
PubMed1982

Leaching of unpolymerized materials from orthodontic bonding resin.

The unpolymerized material extracted from cured orthodontic bonding resin was analyzed by UV spectrophotometry. Under certain conditions, substantial amounts of the material (approximately 14%) were leached from bracketed teeth. The possible carcinogenicity of these unpolymerized materials is discussed.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1980

A technique for intraradicular dental implants.

A technique utilizing nonvital roots for the support of intraradicular dental implants has been developed and tested. Using this technique it may be possible to preserve the roots of teeth that would normally be lost because of periodontal involvement. In this technique, a suitable tooth is treated endodontically. The crown is then removed to the height of the alveolar crest, and the root is drilled and tapped to accept a threaded stainless steel Heli-Coil insert. The root is then covered with a gingival flap. This allows for the regeneration of periodontal tissues around the root while it isolated from the oral environment. Following the period of natural healing, a stainless steel post is threaded into the Heli-Coil root implant. In the present studies (canine roots in a rhesus monkey) the implant posts are fitted with Adaptic crowns. These implants have been in place for more than 6 months with no sign of implant failure.

Animals↗
PubMed1979

Effect of pneumatic tourniquet application to the distal extremities of the horse: blood gas, serum electrolyte, osmolality, and hematologic alterations.

With 120 minutes of pneumatic tourniquet application to the distal extremity in the horse, the following effects were noted in the tourniqueted limb vein (TLV): (i) local venous acidemia, (ii) increase in serum K+ concentrations, (iii) minimal changes in plasma total solids, Na+, or osmolality, and (iv) apparent reduction in hematocrit values when compared with the same measurements in the control leg. Tourniquet release after 120 minutes produced a prompt return to base line for PCV and PO2 in the TLV; however, pH, PCO2 and K+ values in the TLV required 10 to 15 minutes to reach base line (TLV or control leg vein).

Animals↗
PubMed1975

Dissociation of the DNA replicase system of bovine lymphocyte nuclei.

Exposure of S-phase nuclei or subnuclear preparations from phytohemagglutinin-stimulated bovine lymphocytes to 0.02 M ATP caused an immediate and almost total loss of their ability to replicate DNA in vitro. Other ribonucleoside and deoxyribonucleoside triphosphates caused a similar inhibition of DNA replication. Levels of ATP which inhibit replication cause the release of DNA polymerases alpha and beta and small pieces of DNA from these nuclei. This release occurs both at 4 and 37 degrees C. The data support the conclusion that high levels of ATP or other nucleoside triphosphates inhibit DNA replication in nuclei by dissolution of the DNA replication complex. The limited success in reconstitution of the DNA replicase complexes is discussed.

Adenosine Triphosphate↗
PubMed1975

DNA replication in nuclei isolated from bovine lymphocytes.

DNA replication was studied in nuclei isolated from phytohemagglutin-stimulated bovine lymphocytes. The mitogen treatment induced more than 60% of these cells to engage in DNA synthesis with a peak of synthetic activity occurring about 48 h after the addition of phytohemagglutinin. Throughout this response the ability of isolated nuclei and nuclear sonicates to synthesize DNA in vitro was proportional to the synthetic ability of the intact cells of origin. The subcellular systems appear to continue synthesis at replicative sites which were active in vivo. The rate of in vitro synthesis by both nuclei and nuclear sonicates was about two-thirds that of intact cells. The one cytoplasmic and two nuclear DNA polymerase activities separated from these cells were found to have properties similar to those of other eucaryotic cells.

Animals↗
PubMed1975

Chronic meningoencephalomyelitis with spastic spinal paralysis: a case report.

A case of chronic meningoencephalomyelitis in a 48-year-old housewife is presented. The onset was characterized by spastic paralysis of the lower extremities. The course was progressive with repeated remissions and exacerbations, and the patient died approximately seven years after the onset of disease. Laboratory tests showed slightly increased cell count in the spinal fluid, accelerated sedimentation rate, positive CRP and RA, and increased ASLO and gamma globulin levels. Neuropathologic examination revealed such changes as perivascular cellular infiltration, glial nodules, poorly demarcated demyelination and recent necrosis in the spinal cord and basal ganglia. Only mild inflammatory findings were noted in the telencephalon and brain stem. The clinico-pathologic findings in this case supported a diagnosis of chronic meningoencephalomyelitis which could not be classified as any known type of encephalomyelitis.

Chronic Disease↗