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Biomedical subjects

J Cone

Publications and source records attributed to J Cone.

At least 37 records · Page 2Linked to original sources
PubMed1991

Expectations and high school change: teacher-researcher collaboration to prevent school failure.

Describes the multilevel outcomes of a collaborative preventive intervention for ninth-graders at risk for school failure using qualitative and quasi-experimental methods. Teachers, administrators, and researchers implemented innovative practices communicating positive expectations for low-achieving adolescents in their transition to high school. Changes were made in the practices of curriculum, grouping, evaluation, motivation, student responsibility, and relationships (in the classroom, with parents, and in the school). Both implementation and evaluation evolved as a function of collaboration. Change was promising but not uniform. Project teachers became more positive about students and colleagues, expanded their roles, and changed school tracking policies. The 158 project students, in contrast to the 154 comparison students showed improved grades and disciplinary referrals post-intervention and increased retention in school 1 year later, but their absences rose and improved performance was not maintained. The implications of this analysis for school-based interventions and its evaluation are discussed.

Adolescent↗
PubMed1991

CARET, the beta-carotene and retinol efficacy trial to prevent lung cancer in asbestos-exposed workers and in smokers.

CARET is a two-armed, double-blind, randomized chemo-prevention trial to test the hypothesis that oral administration of beta-carotene 30 mg/day plus retinyl palmitate 25,000 IU/day will decrease the incidence of lung cancer in high-risk populations: heavy smokers and asbestos-exposed workers who have smoked. The agents combine anti-oxidant and nuclear tumor suppressor mechanisms. Fastidious monitoring for possible side effects is facilitated by inclusion of a Vanguard population. As of 31 December 1990, 6,105 participants of the 18,000 needed have been randomized in the trial. Efficacy results are expected in 1999.

Aged↗
PubMed1991

Neuropsychological impairment among former microelectronics workers.

Although chemicals posing potential neurotoxic hazards are commonly used in the microelectronics industry, there has been no systematic study of possible chronic nervous system effects in microelectronics workers. The objective of the present study was to assess neuropsychological functions of a group of former microelectronics plant assembly workers and a group of referents, using a matched pair design. During employment, the former microelectronics workers had been exposed to multiple organic solvents, including trichloroethylene, xylene, chlorofluorocarbons and trichloroethane. Referents were recruited from the same geographic region. From a pool of 180 former workers and 157 referents, 67 pairs were matched on the basis of age, sex, ethnicity, educational level, sex and number of children. Comparison of results on the subtests of the California Neuropsychological Screening Battery-Revised (CNS-R) revealed significantly lower performance by the former microelectronics workers on tests of attention/concentration, verbal ability, memory functions, visuospatial functions, visuomotor speed, cognitive flexibility, psychomotor speed, and reaction time (t-test for pairs or Wilcoxon Signed Rank p less than 0.05). No significant differences were observed for performance on tests assessing mental status, visual recall, tactile function and learning. This overall pattern of impairment is consistent with organic solvent-related chronic toxic encephalopathy, and possible early stages of dementia. These findings underline the need for more studies among workers currently or previously employed in microelectronics industries.

Adult↗
PubMed1990

Blood conservation techniques in orthopaedic surgery.

In summary, reduction of blood loss and coincidental decrease in the number of blood transfusions is now of paramount importance in orthopaedic surgery. Methods to reduce blood loss include preoperative planning, hypotensive anesthesia, and meticulous surgical technique. If transfusion is necessary, autologous replacement is always preferable. Overall, the goals in blood conservation in surgery are first to decrease the amount of blood lost, and second to be sensible in replacement of this loss.

Blood Transfusion↗
PubMed1990

Blood products: optimal use, conservation, and safety.

A review of our experience in total joint arthroplasty revealed that the cell saver was not cost-effective in the case of routine primary hip or knee replacement. Its use should be restricted to cases of revision hip and knee surgery in which infection has been ruled out. Preoperative aspiration remains the most reliable method for accomplishing this. However, if the aspiration is negative and the intra-articular fluid obtained at the time of surgery is suspicious for infection, either in appearance or on Gram stain or cell count, it is best to abandon use of the cell saver. Predonation should be routine for all hip replacement cases unless there are specific contraindications. In general, there is good acceptance of this program by patients, although a few have specifically indicated they would prefer to run the risk of homologous transfusion. Two units available for primary replacement are more than ample. In cases of revisions, a first revision justifies a minimum of 3 units. For complex revision cases involving patients with three or more previous procedures on the hip, or those requiring significant bone resection or large segment grafting, the maximum possible number of units should be obtained. Autologous blood reinfusion should be done for essentially the same indications as homologous transfusion even though risks are sharply reduced. The local source for autologous collection will then follow its own specific protocol for the disposition of remaining units. In every case, the surgical technique should be careful and directed toward limiting intraoperative blood loss.

Blood Transfusion, Autologous↗
PubMed1990

Methylene chloride intoxication in a furniture refinisher. A comparison of exposure estimates utilizing workplace air sampling and blood carboxyhemoglobin measurements.

A 35-year-old furniture refinisher came to the occupational medicine clinic with complaints of upper respiratory irritation, fatigue, and lightheadedness occurring on a daily basis after using a methylene chloride-containing paint stripper. Determinations of blood carboxyhemoglobin (COHb) on three occasions showed an apparently linear elevation of COHb as a function of hours worked on the day of sampling. COHb levels predicted from spot industrial hygiene measurements were in close concordance with those observed in the patient, indicating the potential usefulness of COHb monitoring in estimating airborne exposure levels. Methylene chloride (or dichloromethane) is an organic solvent that has found wide use as a degreaser, paint remover, aerosol propellant, and a blowing agent for polyurethane foams, and as a solvent in food processing, photographic film production, and plastics manufacturing. Discovery of its unusual metabolic fate--conversion to carbon monoxide in vivo--has earned the compound a special place in the solvent toxicology literature. Demonstration of oncogenicity in experimental animals has occasioned a reconsideration of exposure limits, with emphasis upon stricter controls. In some workplaces, conditions prevail in which controls are inadequate to prevent even acute toxicity, much less long-term exposure risks.

Adult↗
PubMed1988

Correlated in vivo 31P-NMR and NADH fluorometric studies on gerbil brain in graded hypoxia and hyperoxia.

Mitochondrial energy coupling in the gerbil brain was characterized by the relationship between intracellular phosphocreatine (PCr)/inorganic phosphate (Pi), phosphorylation ratio, and the mitochondrial redox state in graded hypoxia. Phosphorus-nuclear magnetic resonance (NMR) spectra of the brain and whole head were taken by surface and saddle coil, respectively. The NADH level of the brain cortex was monitored by in vivo fluororeflectometry. The PCr and Pi of the head and brain did not change between 100 and 10% O2 inhalation. PCr progressively decreased and Pi progressively increased with 6 and 4% 0% inhalation in the head. The PCr/Pi of the brain decreased by 44% at 6% fraction of inhaled oxygen (FIO2) and 57% at 4% FIO2. The ATP level did not change during hypoxia. The calculated phosphorylation ratio of the brain ([PCr] Kck[H+]/[Cr][Pi]) = ([ATP]/[ADP][Pi]) was 4.1 X 10(4) M-1 in normoxia. Hypoxia of increasing severity induced increasing NAD reduction of the brain cortex with 17% NAD reduction at 10% FIO2 when there was no change in phosphorylation ratio. The phosphorylation ratio decreased, i.e., the mitochondria failed to maintain the energy level of the brain when the magnitude of the change in NAD reduction to hypoxia was half of the total redox change between hyperoxia and anoxia. These studies demonstrated the feasibility of combined 31P-NMR and NADH fluorometry measurements on brain in vivo. The observations show similarities between the responses of mitochondrial oxidative phosphorylation to hypoxia in vivo and in vitro.

Algorithms↗
PubMed1986

31P NMR detection of mobile dog brain phospholipids.

The in vivo dog brain 31P NMR spectrum has a large peak in the phosphodiester region accounting for more than 35% of the total observable phosphorus metabolites. It is possible to reduce the intensity of this peak by off-resonance saturation. To characterize the nature of this peak, extracts of dog brain frozen in situ were analyzed by high resolution 31P NMR. ATP, phosphocreatine, inorganic phosphate, and phosphomonoesters were recovered in appropriate amounts in the methanol:HCl extract. However, acid soluble phosphodiesters accounted for only 8% of the observable phosphorus. More NMR observable phosphodiesters were selectively recovered following CHCl3:methanol extraction of phospholipids. These results suggest that the in vivo phosphodiester resonance has substantial contributions from a fraction of mobile brain phospholipids.

Animals↗
PubMed1986

Purification of murine erythropoietin produced in serum-free cultures of erythroleukemia cells.

We previously documented that several erythroleukemia cell lines released factors that stimulated erythropoiesis in vivo and in vitro. A simple five-step scheme has been devised that allows purification of this erythropoietic activity to apparent homogeneity. The methods employed included lectin affinity chromatography (wheat germ agglutinin), gel filtration (ultro gel ACA44), ion exchange, hydroxylapatite, and high performance liquid chromatography. Following polyacrylamide gel electrophoresis, biologic activity was recovered in an area corresponding to a molecular weight of 35,000 daltons. Silver staining of a polyacrylamide gel after electrophoresis of our most purified preparation revealed a single band at 35,000 daltons.

Animals↗
PubMed1984

Somatosensory evoked potential monitoring during the management of aneurysmal SAH.

Somatosensory evoked responses to median nerve stimulation have been recorded during the management of subarachnoid hemorrhage from intracranial aneurysms. The type of measurement was central conduction time (CCT), the time interval between the N14 peak (at C-2) and the N20 peak (at the cortex). Significant differences were found between patients with aneurysms in clinical Grade 4 and normal individuals, although there was no significant difference between most aneurysm patients in Grades 1 through 3. The prolongation of CCT was found of prognostic value. Significant prolongation (mean plus two standard deviations) from the normal period of 5.4 +/- 0.4 msec was found significantly useful to predict a less than satisfactory outcome (a patient with neurological signs or disabled) at 2 months, and these differences were detectable as early as 48 hours postoperatively. Differences between conduction time in the two hemispheres could also be used prognostically, although the significance of the differences did not appear until 48 to 72 hours after surgery, and was in any event less than that of CCT.

Adult↗
PubMed1979

Computerized tomographic scan and gunshot wounds of the head: indications and radiographic findings.

The authors document their experience with the computerized tomographic (CT) scanner for evaluating gunshot wounds of the head. Only those patients who were considered to be operative candidates and who were neurologically stable were scanned. In the postoperative period, patients who were not scanned preoperatively and those whose condition did not improve were also scanned. In the preoperative period the CT scanner is useful for identifying and localizing missile tracks, bony and metallic fragments, intra- and extraparenchymal hematomas, intracranial air, and brain swelling. In the postoperative period the CT scanner may demonstrate retained bone fragments, edema, brain abscess, and intracranial air. The limitations of the CT scan in evaluating gunshot wounds include an inability to define vascular lesions suchas traumatic aneurysms and post-traumatic spasm. Metallic scatter from missile fragments may render certain CT cuts uninterpretable. In addition, the CT scan may appear minimally abnormal in spite of immediate and irreversible injury caused by a shock wave transmitted to brain stem structures. The CT scanner has superceded angiography as a diagnostic tool for evaluating gunshot wounds of the head because it is noninvasive and rapid, allows visualization of the entire head, can resolve very small lesions that produce little or no mass effect, can help to determine the nature of intracranial lesions and may quantitate the amount of hemorrhage and edema. Because it enables physicians to visualize intracranial structures in three dimensions, the CT scan may precisely define missile tracks and contiguous lesions in a manner not heretofore possible with other diagnostic modalities. Thus, it is invaluable for the rational planning of surgical therapy.

Brain Injuries↗
PubMed1976

Transplantation in miniature swine. I. Fixation of the major histocompatibility complex.

Three strains of miniature swine, each homozygous for a different allele of the major histocompatibility locus (MHC), have been developed by a selective breeding scheme based on tissue typing of the offspring of each generation. Prior to breeding, the original parents were reciprocally immunized by skin grafts and lymphocyte injections to produce lymphocytotoxic antisera. These antisera were then used to assess the MHC genotype of the offspring by an analysis based on selective absorption of cytotoxicity. Offspring inheriting the same serologically determined genotype were then bred sequentially. Subsequent mixed lymphocyte cultures showed a pattern of reactivity consistent with the serological genotyping, further confirming the homology between the MHC of these miniature swine and those of man and mouse. In addition to their usefulness as a model for large animal surgical transplantation, these animals provide an abundant homozygous source of histocompatibility antigens and of antihistocompatibility antisera for use in chemical characterization of products of the MHC.

Animals↗
PubMedDate not supplied

Colour vision loss among disabled workers with neuropsychological impairment.

Test performance on a neurobehavioural battery was examined with respect to acquired colour vision loss among patients with a history of neurotoxin exposure. The study group included 14 men and 7 women with clinically diagnosed neuropsychological impairment (mean age: 41.3 +/- 8.1 years; mean educational level: 13.4 +/- 1.4 years). Verbal and visual ability, memory and psychomotor function were assessed with the California Neuropsychological Screening Battery. Colour vision was assessed with the Lanthony D-15 desaturated colour arrangement panel. Acquired dyschromatopsia was present in 17 patients (80.9%), 11 of whom manifested patterns of Type II colour vision loss. Simple regression analysis of neuropsychological test performance with respect to colour vision loss, using age-adjusted Z-scores, revealed significant relationships (p less than or equal to 0.05) solely for tests which rely heavily on the visual system. Significant differences in visual task test scores were also observed with the type of dyschromatopsia (Kruskal-Wallis, p less than or equal to 0.05). These findings suggest that poor performance on visual tasks and colour vision loss may both result from damage to neuro-ophthalmic pathways or that loss of integrity of the peripheral visual pathways may affect visual task performance. The authors propose that visual testing should be incorporated into neurobehavioural test batteries.

Adult↗