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Biomedical subjects

S Reid

Publications and source records attributed to S Reid.

At least 145 records · Page 8Linked to original sources
PubMed1990

Effects of axis placement on measurement of isokinetic flexion and extension torque in the lumbar spine.

We wanted to ascertain whether changing the machine axis placement relative to the anatomic landmarks of a tested subject in isokinetic flexion and extension trunk strength would influence the measurements obtained. Twenty healthy volunteers were tested with the machine axis intentionally displaced from a reference position at the lumbosacral junction. Displacing the axis 50 mm vertically produced on average 15% increase in the torque produced, and displacing it 10 mm horizontally produced approximately 5% reduction in torque, independent of the direction of displacement from the reference position. The angle at which maximum torque occurred and the ratio of extension to flexion torque were unaffected by axis placement. Intertester reliability in axis placement was found experimentally to produce variations of usually less than 10 mm. We conclude that isokinetic trunk strength measurement is affected by testing axis placement; this should be controlled, especially in repetitive testing of the same individual.

Adult↗
PubMed1989

Regression of experimental cancer by oral administration of combined alpha-tocopherol and beta-carotene.

alpha-Tocopherol (vitamin E) and beta-carotene have been shown to be capable of regressing established epidermoid carcinomas of hamster buccal pouch when injected locally into the tumor site. Neither has yet been shown to be effective in regressing cancer when administered by oral route. However, a combination of both alpha-tocopherol and beta-carotene was shown to be effective in regressing epidermoid carcinomas of hamster buccal pouch when the mixture was administered orally in vegetable oil. The epidermoid carcinomas were induced in the right buccal pouch of 100 Syrian hamsters by painting three times weekly for 14 weeks with a 0.5% solution of 7,12-dimethylbenz[a]anthracene in mineral oil. The animals were then divided into five equal groups of 20 animals. Group 1 animals received no further treatment and represented tumor controls. Group 2 animals received 200 micrograms beta-carotene and 200 micrograms dl-alpha-tocopherol acid succinate combined in 0.2 ml vegetable oil. Animals received the mixture daily by mouth using a 1-ml syringe. Groups 3 and 4 received beta-carotene and alpha-tocopherol individually in double amounts (400 micrograms in 0.2 ml vegetable oil). Group 5 animals received only the vegetable oil (0.2 ml daily) and were controls for vehicle. The animals in Groups 1, 3, 4, and 5 were killed after 22 weeks because the tumors were extensive, large, and necrotic and the animals were weak and cachectic. After 22 weeks, the tumors in Group 2 animals were small in 15 out of 20 animals. The tumors were reduced in size compared with tumor burden at 14 weeks, the point at which the beta-carotene/alpha-tocopherol was started.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Recurrent outbreaks of giardiasis in a child day care center, Wisconsin.

In the 19-month period September 1983-March 1985, three outbreaks of giardiasis occurred in one large child day care center. Control measures instituted during each outbreak included case finding; pharmacologic treatment and follow-up testing of stool specimens for cases of giardia infection in day care children and staff, and their household contacts; facilitating and stressing personal and environmental hygiene, including altering diapering practices and teaching appropriate hand washing techniques. In the first, second, and third outbreaks, overall attack rates (stool analysis positive for Giardia lamblia) were determined for those persons with greater than or equal to 2 stool specimens submitted; attack rates in children were 47, 17, and 37 per cent, respectively; for tested staff, the rates were 35, 13, and 9 per cent; and for tested household contacts were 18, 9, and 5 per cent. Attack rates were highest for ambulatory diapered children, children attending the day care center greater than or equal to 40 hours per week, and children who were infected with G. lamblia in the most recent previous outbreak. Despite extensive efforts to identify cases, a cure rate of greater than 90 per cent in treated cases, and improvements in personal and environmental hygiene practices, G. lamblia infections recurred in outbreak proportions.

Child Day Care Centers↗
PubMed1989

Functional restoration with behavioral support. A one-year prospective study of patients with chronic low-back pain.

Patients with chronic disabling low-back pain have poor prospects of returning to work. The authors tested a treatment program of functional restoration with behavioral support through 1 year prospective observation of patients disabled for an average of 19 months without evidence of surgically correctable disease. Ninety patients were studied: 59 program graduates, five program dropouts, 17 patients denied program authorization by their insurance carriers, and six crossover patients. Three patients were admitted but refused to participate in the treatment program. Initial demographic, physical, and self-assessment attributes were similar for all four groups. At year's end, 81% of program graduates, 40% of the dropouts, and 29% of those denied the program had returned to work. All six crossover patients were working 6 months after treatment. Program graduates showed significant improvements in self-assessed pain, disability, and depression, and in physical capacities after 3 weeks of treatment. These improvements were maintained through the year except for partial decreases in frequent lifting, cycling endurance, and isokinetic trunk extension strength. Functional restoration with behavioral support is an effective treatment for patients with chronic, disabling low-back pain, as measured by self-assessments, physical capacities, and return to work.

Back Pain↗
PubMed1989

Diagnosis of recessive X-linked ichthyosis: quantitative HPLC/mass spectrometric analysis of plasma for cholesterol sulfate.

A specific, accurate liquid-chromatographic/mass-spectrometric (HPLC/MS) method for measurement of cholesterol sulfate in plasma from normal individuals and patients with recessive X-linked ichthyosis (RXLI) is described. The method is superior to previously described techniques because it measures the analyte intact rather than after hydrolysis. Traces of free cholesterol in the sample analyzed do not add to the measured result. We used either [13C2]cholesterol sulfate or [2H6]cholesterol sulfate as internal standards, which we add to plasma before extraction. Use of such standards makes quantitative extraction unimportant. We use a single solid-phase extraction (SPE) C18 cartridge for plasma extraction. After the cartridge is washed with methanol/ammonium acetate solutions, the fraction containing the steroid sulfates is eluted with methanol, evaporated, and subjected to HPLC/MS analysis, wherein the molecular anions of analyte and internal standards are monitored. The peak ratio gives the cholesterol sulfate concentration directly. Using this method, we have diagnosed 24 patients with RXLI. Their concentration of cholesterol sulfate ranged between 41.7 and 185.3 mumol/L (mean 93.85, SD 31.2 mumol/L). In normal individuals (n = 9) the mean cholesterol sulfate concentration was 2.77 mumol/L (SD 0.62, range 2.05-3.95 mumol/L). The instrumentation required is complex, but the assay is simple: sample preparation takes about 30 min; mass spectrometry, 10 min. About 0.1 mL of plasma is required for cholesterol sulfate measurement in RXLI patients and 0.5-1 mL in normal individuals.

Adult↗
PubMed1988

Prevention of experimental oral cancer by extracts of Spirulina-Dunaliella algae.

An extract of Spirulina-Dunaliella algae was shown to prevent tumor development in hamster buccal pouch when a 0.1% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil was applied topically three times weekly for 28 weeks. The algae extract was delivered by mouth in continued dosages of 140 micrograms in 0.4 ml mineral oil three times per week. After 28 weeks, the animals given vehicle and untreated controls all presented gross tumors of the right buccal pouch. Animals fed canthaxanthin presented a notably and statistically significant reduction in tumor number and size compared with controls. Animals fed beta-carotene demonstrated a smaller but statistically significant reduction in tumor number and size. The algae animals presented a complete absence of gross tumors. However, microscopic sections of the buccal pouch in the algae group showed localized areas of dysplasia and early carcinoma-in-situ undergoing destruction.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Isokinetic trunk and lifting strength measurements: variability as an indicator of effort.

This study examines the hypothesis that force/distance curve variability distinguishes submaximal from maximal efforts in isokinetic trunk and lifting strength tests. Thirty normal subjects were tested on the Cybex Trunk Extension/Flexion (TEF) and Liftask (LT) machines during maximal (100%) and submaximal (50%) efforts. Considering each test separately, visual assessments of curve variability were indeterminate of degree of effort in 28% of TEF and 34% of LT tests. Measurement models of curve variability were more clearly discriminating. When a given subject's test curves were considered together, scaled visual assessments identified the degree of effort in 91% of TEF and 86% of LT results. The measurement models were accurate 90-92% of TEF and 79-92% of LT results. Clinical judgment is required in evaluating effort during tests of isokinetic trunk and lifting strength.

Adult↗
PubMed1988

Spinal pedicle fixation: reliability and validity of roentgenogram-based assessment and surgical factors on successful screw placement.

The increased popularity of pedicle fixation prompted research to address two issues: the reliability and validity of roentgenograms as a technique for evaluating the success of pedicle fixation, and the effects of surgical factors on successful fixation. Thus, does approach--the point and angle of screw insertion, surgeon experience, practice, level of the spine involved, and screw size--effect success of pedicle fixation? Eight fresh thoracolumbar spines were harvested and cleaned of all soft tissues. Two surgeons, one more experienced in pedicle fixation than the other, used two pedicle fixation approaches (Weinstein and Roy-Camille) on both the left and right sides at levels T11-S1 of each specimen. All screws were placed under anteroposterior (AP) and lateral c-arm control. For specimens 1 to 3, 5.5 mm screws were used at T11-L1, and 7.0 mm screws at L2-S1. Unacceptable failure rates at L2 and L3 for the first three specimens resulted in a change of instrumentation for the remaining specimens, with 5.5 mm screws used at T11-L3 and 7.0 mm screws at L4-S1. When surgeons completed the fixations for a specimen, AP and lateral roentgenograms were taken and both surgeons independently evaluated the films to assess the success of each fixation. Failure was defined as evidence of any cortical perforation on any side of the pedicle in or outside of the spinal canal. After completing the roentgenogram evaluation, the specimen was transected in the midline, and the success of each pedicle fixation was evaluated by visual/tactile inspection. There were no disagreements between surgeons on the visual/tactile evaluations of the specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Screws↗
PubMed1988

A competitive inhibition ELISA as a probe for studying the refolding of human serum albumin.

The refolding of iodoacetic acid-blocked human serum albumin (HSA) was studied using a modified competitive inhibition ELISA. A maximum of 89% native activity was detected 24 hours after initiating refolding using an albumin concentration of 600 micrograms/mL. The presence of both monomer and polymer HSA was studied using native polyacrylamide gel electrophoresis of thiol-blocked HSA samples. Monomer HSA was not detected until 2.5 hours after initiating refolding. Fractionated polymer and monomer HSA from a sample trapped at 72 hours after initiating refolding was determined to have 40% and 87% native activity respectively. Both polymer and monomer HSA fractions contribute to the overall immunological activity detected by the ELISA, at various times. The ELISA assay was able to detect the changing HSA conformation associated with refolding of totally reduced HSA.

Chromatography, Gel↗
PubMed1987

Use of nude mouse xenografts as preclinical screens. Characterization of xenograft-derived melanoma cell lines.

Cell lines derived from human melanoma xenografts were characterized for surface markers, karyotype abnormalities, and in vitro drug sensitivity. Xenografts were established using metastatic explants from untreated patients and passaged in nude mice. Cell lines were readily established from melanoma xenografts, and formed colonies when plated in semisolid media. The lines expressed human melanoma-associated and other surface antigens, human lactate dehydrogenase (LDH) isoenzymes, and contained only human chromosomes. They failed to express murine histocompatibility determinants and were negative for murine viruses by mouse antibody production assay. Karyotypes showed abnormalities of chromosomes 3, 6, and 7 similar to other melanomas. In vitro chemosensitivity profiles were compared using cell line and xenograft colony-forming assays. Values were similar for the original xenografts and their cell lines. Xenograft-derived human melanoma lines resemble other melanoma cell lines and primary melanomas with respect to surface antigens and karyotype abnormalities, and are appropriate models for studying in vitro drug sensitivity. When used as a model for transition from solid tumor to cell line, these studies suggest cell lines closely mirror in vitro chemosensitivities of parent tumor cells. However, occasional, unpredictable changes in sensitivity to some drugs occurs during this transition.

Animals↗
PubMed1987

Glycolysis--new concepts in an old pathway.

A survey of the existing data on the interactions of glycolytic enzymes with the cellular structure in mammalian tissues has substantiated the occurrence of an extensive degree of such associations in all tissues and during all stages of development. Furthermore, a considerable specificity was evident between the individual multiple forms of the enzymes in relation to these associations. In reviewing these data, a model has been developed which proposes that the glycolytic sequence is best described as consisting of a number of segments in vivo, each segment formed by a cluster of isozymes, many of which can interact with the actin containing filaments of the cytomatrix. The novel features of this segmentation and compartmentation have been described, and evidence has been provided that these phenomena collectively play a key role in meeting the different types of energy requirement in the cytoplasm of divergent cell types, with the wide selection of isozymes in this system offering the potential for increased flexibility and control in this important area of metabolism.

Animals↗
PubMed1987

Isozymes and the micro-organization of the glycolytic sequence.

A study of the ontogenic characteristics of glycolytic enzymes in mammalian tissues has demonstrated an extensive degree of association between these enzymic components and cellular structure in all tissues during development. Furthermore, these associations tended to be highly isozyme specific. In reviewing these data, a model has been developed which describes the novel features of this compartmentation-by-binding. The glycolytic sequence in vivo is depicted as a number of segments, each formed by a cluster of isozymes, many of which can interact with the actin-containing filaments of the cytomatrix. Evidence is provided that this form of compartmentation plays a key role in meeting the different types of energy requirement in the cytoplasm, with the wide selection of isozymes in this system providing increased flexibility and control in this important area of metabolism.

Animals↗