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Biomedical subjects

J S Schultz

Publications and source records attributed to J S Schultz.

At least 19 recordsLinked to original sources
PubMed1997

A familial predisposition toward lumbar disc injury.

STUDY DESIGN: A retrospective case-control study was performed. OBJECTIVES: To test the hypothesis that there is a familial predisposition to lumbar disc pain and injury. SUMMARY OF BACKGROUND DATA: The few studies that have addressed this question have suggested that a familial predisposition is present, but the techniques used for identifying discogenic pain and accounting for potentially confounding extrinsic factors make it difficult to formulate a clear conclusion. METHODS: Immediate relatives of index patients who had surgically proven lumbar disc herniations (disc/case subjects) or repetitive upper extremity overuse syndromes (upper extremity/control subjects) were given a questionnaire that had been tested previously and found to reliably identify discogenic lower back pain. The prevalence of lumbar disc pain and injury was determined in the two groups of patients; logistic regression was used to control for demographic factors and activities known to increase risk for lumbar disc injury. RESULTS: The questionnaire was returned by 60 (59%) of 102 disc subjects and 41 (50%) of 81 upper extremity subjects. Sixteen (28%) disc subjects and one (2%) of the upper extremity subjects met questionnaire criteria for discogenic lumbar pain; seven (12%) disc subjects and no upper extremity subjects had received surgical therapy for lumbar disc pain. Logistic regression analysis identified familial grouping and a history of lifting as the only variables associated with a positive response on the questionnaire. Information obtained from index patients about their nonresponding relatives' history of significant back pain suggested similar findings. CONCLUSIONS: There is a familial predisposition toward lumbar disc pain and injury. This information may be helpful in occupational counseling or for targeting specific populations with preventative, interventional strategies.

Adult↗
PubMed1994

Chemical sensors and biosensors for fluoride: current status and developing technologies.

Portable sensors for bioanalytes are becoming of increasing interest, because their development will permit analyses of biological samples at the point of sampling, i.e., at the time when an individual is being examined by a health professional. In this paper, the design requirements for a fluoride sensor are outlined. Currently, commercially available fluoride sensors, ion-selective electrodes, do provide the capability to measure fluoride content in samples directly. However, the sensitivity of these devices is lower than the normal content of fluoride in plasma, and thus, samples must be concentrated before measurement. Recent progress in improving the sensitivity of chemical sensors for fluoride shows sensitivities up to 0.1 mumol/L, which is within the range of interest. In addition, the use of biological systems for developing sensors (biosensors) is expanding rapidly, because of the potential of achieving high selectivity and sensitivity through the use of the amplification power of enzymes. However, relatively few enzyme systems have been discovered that are affected by fluoride--thus the need for expanded research to find appropriate enzymes for this purpose. The characteristics of some enzymes, such as adenylate cyclase, that could be used in the development of a fluoride biosensor are discussed.

Biosensing Techniques↗
PubMed1992

Enhancement of cell production in long-term bone marrow culture.

In an effort to increase the long-term production of hematopoietic cells in vitro, Origen hybridoma cloning factor (HCF) was added at the initiation of Dexter type cultures, in which whole bone marrow (BM) was seeded into tissue culture flasks and formed an adherent stromal layer that supported the proliferation and differentiation of primitive cells. After about six weeks, all the cultures were fully established, and continuous production of nonadherent cells was maintained for at least 27 weeks. In the groups with 20% HCF, there was a significant (three- to fourfold) increase in the steady-state cell production of 106 +/- 17 x 10(4) cells/ml compared to 26 +/- 10 x 10(4) in controls. In some cases the ability of HCF to increase productivity was limited by the nutrients and metabolic products in the culture medium. Cell number varied inversely with glucose and pH. HCF increased the concentration and absolute number of myeloid progenitors (granulocyte-macrophage colony forming units and spleen colony forming units) in the nonadherent layer and shifted the differentiation of granulocyte-macrophage colony forming units toward the production of cells of the monocyte/macrophage lineage. Spleen colonies produced from 10(5) cells from cultures with HCF were more numerous (8 +/- 2 versus 4 +/- 2) and larger than those from control cultures (2.6 versus 0.2 mg/colony), but they contained the usual cell lineages (erythrocytic, granulocytic and megakaryocytic).

Animals↗
PubMed1992

Long thoracic neuropathy from athletic activity.

Four cases of long thoracic mononeuropathy associated with sports participation are presented. Each patient developed shoulder pain or dysfunction after an acute event or vigorous activity, and demonstrated scapular winging consistent with serratus anterior weakness. The diagnosis was confirmed with electromyography in each case. It is suggested that the athletic activity caused a stretch injury to the long thoracic nerve. Conservative management, consisting of range of motion exercises for the shoulder and strengthening of the serratus anterior muscle, resulted in a favorable outcome in all patients.

Adolescent↗
PubMed1991

Determining the extent of labeling for tetramethylrhodamine protein conjugates.

A new, relatively simple, spectrophotometric technique has been developed which is useful for accurately determining the extent of chromophore labeling of proteins. Often the absorbance spectra and extinction coefficients of dye/protein conjugates are strongly affected by changes in the chromophore microenvironment that may occur at high dye/protein ratios. In the method being presented, the microenvironment effects have been significantly reduced by denaturing the dye/protein complex in 6 M guanidine hydrochloride prior to making the necessary spectrophotometric measurements. With this approach, extinction coefficients were obtained under native and denatured conditions for tetramethylrhodamine isothiocyanate (TRITC) when bound to a model protein receptor, the sugar binding protein concanavalin A (ConA). The extinction coefficients used for TRITC/ConA conjugates under native and denaturing conditions were 6.52 x 10(4) M-1 cm-1 and 6.96 x 10(4) M-1 cm-1, respectively. These values were obtained from a model dye complex formed between TRITC and epsilon-amino-n-caproic acid which closely resembles the sidechain of lysine residues. Additional dye/ConA conjugates were prepared with tetramethylrhodamine succinimidyl ester (RHS) and eosin isothiocyanate (EITC), and the effects of microenvironment changes on these conjugates were examined. Extinction coefficients for these dyes in native and denaturing conditions, as a function of the degree of labeling, were not appreciably different indicating that changes in the microenvironment did not have a significant affect on the spectral properties of these two dyes. In summary, with this new approach it is quite easy to accurately determine the dye/protein ratio for TRITC conjugates. Also, it is expected that RHS would be a better dye than TRITC for protein conjugation because more accurate values for dye/protein ratios can be obtained under native conditions.

Concanavalin A↗
PubMed1991

Biosensors.

Explore the source record for details and available documents.

Biosensing Techniques↗
PubMed1991

Arm ergometry exercise testing in patients with dysvascular amputations.

The purpose of this study was to test the agreement between the heart rate (HR) response and rating of perceived exertion (RPE) on an arm ergometry graded exercise test (GXT) in deconditioned persons with acute dysvascular amputations before and after an inpatient rehabilitation program. Twenty-six men were studied at admission, and 11 were retested after completion of the program. After obtaining resting measurements of HR and systolic and diastolic blood pressures, each patient performed the GXT using an arm ergometer. Patients maintained a cranking rate of 50rpm, which was monitored electronically. The workloads started with a warm-up period of 0 watts (stage 1) and increased by increments of 5 watts. Each stage lasted three minutes-2.5 minutes of exercise and 30 seconds of rest. The RPE was taken five seconds before the end of each exercise stage. During the rest period, HR and blood pressures were recorded. Scatter plots and linear regression analyses revealed no statistically significant relationship, either at early stages of GXT or at peak work, between HR and RPE. The results suggest that RPE cannot be used reliably as a surrogate for direct pulse measurement in exercise training of persons with acute dysvascular amputations.

Aged↗
PubMed1990

Rehospitalization after initial rehabilitation for acute spinal cord injury: incidence and risk factors.

Many acute spinal cord injury (SCI) patients require rehospitalization after discharge from initial rehabilitation. Previous studies of rehospitalization for these patients have been cross-sectional with respect to time since injury (in years), and have not allowed for comparison of patients with equal exposure to the risk of medical complications once they have reentered the community. To examine the incidence, cause, and monetary cost of rehospitalizations during the first year after discharge from initial rehabilitative care (day 365), the medical records of 88 consecutive, acute SCI patients who completed initial rehabilitation at a regional model SCI care system were reviewed. Cases were excluded from the study if the patient was lost to follow-up before day 365. All readmissions to the regional SCI care system during the follow-up period were reviewed for primary diagnosis, length of stay (LOS), and hospital charges incurred. Thirty-four patients (39%) were readmitted at least once by day 365. There was a total of 47 readmissions; mean LOS was 11.9 +/- 2.1 days per admission (+/- 1SE), and mean hospital charge per admission was $9,683. Univariate comparisons between the characteristics of patients who were readmitted vs those who were not indicated that the readmitted group was less educated (11.8 +/- 2.1 years vs 12.9 +/- 0.3 years, p less than 0.05) and had a substantially longer initial rehabilitation LOS (88.9 +/- 6.6 days vs 72.9 +/- 5.1 days, p less than 0.05). Readmissions were less common among patients who were discharged at Frankel class C or D (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Intraocular pressure and visual field defects after argon laser trabeculoplasty in chronic open-angle glaucoma.

Nineteen patients undergoing argon laser trabeculoplasty for open-angle glaucoma were studied prospectively. All patients had glaucomatous visual field defects with inadequate medical control of intraocular pressure (IOP) before laser treatment. All patients had two automated visual fields immediately before laser treatment. They also had follow-up automated perimetry at 1, 4, 8, and 12 months posttreatment. The serial visual fields were compared using a one-way analysis of variance and trend analysis. After the laser trabeculoplasty, six patients showed visual field improvement, eight showed no change, and five showed progressive visual field deterioration. Patients with little fluctuation of IOP measurements after laser treatment had a better prognosis for visual field retention. The mean IOP level, however, was a poor predictor of visual field progression. Patients with more extensive visual field damage before laser treatment did not do worse than patients with less extensive visual field loss.

Aged↗
PubMed1987

Sensitivity and dynamics of bioreceptor-based biosensors.

Bioreceptors can provide the basis for specific and sensitive biosensors. There are many sources of bioreceptors in nature for biochemicals of interest in biotechnology and biomedicine. These bioreceptors (antibodies, enzymes, membrane proteins, binding proteins) can be modified and produced in large quantities using modern biotechnological techniques. The characteristics of the biosensor can also be fine-tuned by modifying the structure of the analog-analyte, which will also provide several orders of magnitude of range sensitivity with a given bioreceptor. The ultimate sensitivity of the biosensor may be limited by the dissociation kinetics of the reaction between analyte and bioreceptor because there is a trade-off between sensitivity and sensor response rate to changes in analyte concentration.

Antibodies↗
PubMed1986

Kinetic analysis in single, intact cells by microspectrophotometry: evidence for two populations of erythrocytes in an individual heterozygous for glucose-6-phosphate dehydrogenase deficiency.

A microspectrophotometric technique was used to measure the kinetics of methemoglobin reduction in intact, unaltered human erythrocytes. Reduction was catalyzed by endogenous NADPH-methemoglobin reductase in the presence of Nile Blue. The technique was applied to the study of erythrocytes from a female donor with decreased glucose-6-phosphate dehydrogenase (G-6-PD) activity. The individual was shown to be heterozygous for deficiency of G-6-PD. The kinetic study revealed two distinct populations of erythrocytes that were nearly equal in number. One cell population showed reduction rates between 0 and 25% of normal, whereas the second cell population displayed rates within the range seen for normal cells. Single-cell indices of cell size, cell hemoglobin content, and ratio of cell hemoglobin to cell size did not correlate with single-cell reduction rates and were not significantly different between the two populations. These results provide quantitative support for the X-inactivation hypothesis in G-6-PD deficiency.

Adult↗
PubMed1986

Accelerated autoimmune disease and lymphoreticular neoplasms in F1 hybrid PN/NZB and NZB/PN mice.

This report describes the first studies of inheritance of autoimmunity in inbred Palmerston North (PN) mice, a model of systemic lupus erythematosus (SLE). Mating of PN mice with the nonautoimmune DBA/2 strain produced evidence that PN disease had a recessive mode of inheritance. When PN mice were crossed with autoimmune NZB mice, female offspring from both crosses developed anti-DNA antibodies and died prematurely with vasculitis, renal disease, and lymphomas. In contrast, reciprocal hybrid males had different patterns of mortality; PN/NZB males from the PN female X NZB male mating had moderately prolonged life spans, whereas NZB/PN males from the opposite cross (NZB female X PN male) had prolonged survival to the mean age of 104 weeks. To determine if testicular hormones were solely responsible for increased longevity in hybrid males, PN/NZB and NZB/PN mice were castrated at 2 weeks of age and compared to sham-operated littermate controls. Prepubertal castration did not influence longevity in PN/NZB males, but loss of gonadal hormones significantly reduced life spans in reciprocal NZB/PN males. Female hybrids were not affected by oophorectomy. Because castration changed disease expression only in male hybrids from the NZB female X PN male cross, it was concluded that parentage influenced sensitivity to the protective effects of male hormones. Although surgical sterilization had disparate effects on males, castrated PN/NZB and NZB/PN males consistently outlived oophorectomized females. The lack of clear-cut reversal of disease in males subjected to early castration suggested that nonhormonal, possibly genetic, factors contributed to longevity in both groups of male hybrids.

Animals↗