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PubMedDate not supplied

Circadian rhythms in human performance efficiency under free-running conditions.

A series of four experiments is described in which two men and two women (age range 22-79 years) were allowed to 'free-run' under conditions of isolation from all time cues. The circadian rhythms of performance efficiency were studied for three tasks: serial search, verbal reasoning, and manual dexterity (left and right hand versions). Strong evidence was obtained to suggest that different tasks are under the control of different circadian oscillators. The circadian rhythm in verbal reasoning performance tends to run at a shorter circadian period than that in more simple repetitive tasks, and slight differences in circadian behavior can occur between left- and right-handed dexterity.

Adult↗
PubMed1983

Central nervous system reactions during heliox and trimix dives to 51 ATA, DEEP EX 81.

UNLABELLED: Two groups of divers were compressed to 500 msw with heliox (n = 3) and trimix (n = 3). They were followed with repeated neuropsychological and neurological tests during compression, at stable intermediate depths, and at 500 msw. For the heliox group there was a marked increase in tremor and EEG slow waves and reduction in handgrip strength. For the trimix group the tremor increase did not occur, but the EEG changes were the same as in the heliox group. On motor tests only the trimix group showed impaired finger dexterity and manual dexterity. The same occurred for fine visuomotor coordination, but both groups had increased intentional tremor. On cognitive tests the same difference occurred. The trimix group was markedly impaired in reasoning and long-term memory, while only a mild impairment was found in the heliox group. Dizziness and other symptoms of high pressure nervous syndrome (HPNS) occurred in both groups. CONCLUSION: There were marked HPNS effects during compression for both groups. Only tremor was inhibited by the nitrogen. In addition, the trimix group was impaired because of nitrogen narcosis. These data indicated that 10% nitrogen did not inhibit HPNS effects during compression to 500 msw, but the considerable differences between subjects shows that susceptibility to compression must be an important area for future research.

Adult↗
PubMed1993

Cytokine expression from bone marrow derived macrophages.

Monocytes and macrophages show marked phenotypic variation dependent on their tissue of origin. Peripheral blood monocytes have been found to be sources of a variety of cytokines, but isolated marrow macrophages have not been characterized in this regard. Marrow macrophages form a predominant component of murine adherent Dexter stromal cells and can be isolated by sequential explant culture in colony-stimulating factor-1 (CSF-1). We have studied murine (Balb/c) bone marrow macrophage (BMM) cytokine production in the presence or absence of CSF-1, the lectin pokeweed mitogen (PWM) or interleukin-3 (IL-3). Biologic activity in conditioned media (cm) from control and induced BMM was assessed using the factor-dependent cell lines 32D, NFS-60, T1165, MC-6 and FDC-P1. Cell line stimulation and antibody blocking indicated the presence of c-kit ligand, interleukin-6 (IL-6) and granulocyte colony-stimulating factor (G-CSF). This stimulatory activity was increased by exposure to PWM or the combination of CSF-1 and PWM or CSF-1 and IL-3. CSF-1, as determined by radioimmunoassay (RIA), was essentially undetectable in baseline cm and induction was not seen with PWM or CSF-1. Baseline or "constitutive" expression of BMM and mRNA for CSF-1 and c-kit ligand was seen. Uninduced BMM did not express mRNA for G-CSF, granulocyte-macrophage CSF (GM-CSF), IL-6 or IL-3. CSF-1 induced increased expression of IL-6 mRNA, PWM induced increased expression of G-CSF and IL-6 mRNA and the combination of PWM and CSF-1 induced expression of CSF-1, G-CSF and IL-6 mRNA. Varying levels of CSF-1 had differential effects on cytokine production. Increasing levels of CSF-1 increased IL-6 mRNA and downmodulated CSF-1 mRNA expression. There was a biphasic response of c-kit ligand mRNA expression to CSF-1 exposure; low levels of CSF-1 (50 U/mL) induced, while higher levels (2000 U/mL) inhibited, expression. These data indicate that BMM (and by analogy the macrophage component of Dexter culture stroma), are important sources of CSF-1 and c-kit ligand but not GM-CSF or IL-3. BMM can also be induced to express IL-6 and/or G-CSF. Lastly, CSF-1, by differentially modulating BMM cytokine production in a holocrine or autocrine manner, may function as a central regulator of stromal based hematopoiesis.

Animals↗
PubMed1994

Can a simple test of visual-motor skill predict the performance of microsurgeons?

A new test of manual dexterity and a test of spatial ability were administered to 37 participants of a microsurgery training course. Performance on microsurgical tasks undertaken by the trainees to assess their surgical skill correlated significantly (rho = -0.54, P < or = 0.01) with manual dexterity and (rho = 0.36, P < or = 0.05) spatial ability. The first of these findings is contrary to those of studies concerned with general surgery whereas the second confirms the results of reported research. Explanation for the results is given in terms of the specific nature of microsurgical skill compared with general surgery.

Adult↗
PubMed1994

Immunologically mediated aplastic anemia in mice: evidence of hematopoietic stromal injury and injury to hematopoietic stem cells.

Immunologically mediated aplastic anemia (AA) results when lymph node cells (LNC) from C3H/He mice are injected intravenously (i.v.) into H-2 identical CBA/J mice previously given 600 cGy sublethal total-body gamma irradiation (TBI). Previously, we showed that T lymphocytes injure pluripotent hematopoietic stem cells and cause severe pancytopenia and death in 80 to 100% of mice within 3 to 4 weeks, with changes in the bone marrow suggesting stromal injury. The following models were used to study the stroma: (1) Transplantation of femurs from AA mice into normal syngeneic CBA/J mice. After 6 weeks, colony-forming unit-spleen (CFU-S) levels in the femur implants were measured in both AA and control mice (600 cGy TBI only). (2) Development of Dexter long-term bone marrow cultures from AA and control mice, which were used to support hematopoietic bone marrow cells (colony-forming units-granulocyte/macrophage [CFU-GM]) from normal mice. (3) Cellulose ester membranes (CEM) were coated with hematopoietic stroma from AA and control mice and then implanted intraperitoneally (i.p.) into syngeneic CBA/J mice. Six months later, the CEM were removed and analyzed for the presence of trilineal hematopoiesis and bone. Injury to the hematopoietic stroma was documented by the following: (1) Femurs from AA mice had a decreased number of CFU-S compared to controls; (2) Dexter cultures from AA mice formed abnormal stromal layers with a decreased capacity to support CFU-GM from normal donor mice; and (3) CEM coated with stromal cells from AA mice had a decreased capacity to support trilineal hematopoiesis and bone compared to CEM coated with marrow stroma from control mice.

Anemia, Aplastic↗
PubMed1994

Efficient retrovirus-mediated gene transduction into murine hematopoietic stem cells and long-lasting expression using a Transwell coculture system.

The neomycin phosphotransferase (neo) gene was transduced into murine hematopoietic stem cells by culturing a recombinant retrovirus-producing cell line in a Transwell (Costar, Cambridge, MA) (bottomed with a porous membrane) hung into a Dexter-type long-term bone marrow (BM) culture. Gene transduction into stem cells retaining long-term reconstitution ability was successfully performed by using protocols of total 15 to 18 days of culture including establishment of the Dexter culture, transduction, and G418 selection. In the irradiated recipients of these cells, a large majority of the BM, thymus, and spleen cells as well as peripheral blood (PB) leukocytes were of donor origin and the neo gene was present in these organs up to 21 weeks after cell transfer. One third to two thirds of the in vitro colony-forming cells in the BM of the recipient mice were resistant to cultivation with G418. It was further found that the hematopoietic system of secondary recipients given BM cells from a primary recipient mouse was predominated by original donor-type cells. The transduced neo gene was detected in the PB, BM, thymus, and spleen cells of these secondary recipients. These results indicate that our procedure of retroviral vector-mediated gene transfer is highly effective in safely introducing a gene into pluripotent hematopoietic stem cells.

Animals↗
PubMed1994

Efficient transfer of selectable and membrane reporter genes in hematopoietic progenitor and stem cells purified from human peripheral blood.

We have utilized highly purified hematopoietic progenitor and stem cells (HPCs, HSCs) from normal peripheral blood to develop methodology for: (a) efficient transfer into HPCs of a non-hematopoietic membrane reporter, i.e., the nerve growth factor receptor complementary DNA; and (b) effective gene transduction of putative HSCs, i.e., cells initiating Dexter-type long-term culture (LTC-ICs). Purified HPCs induced into cycling by growth factors (interleukin 3, interleukin 6, c-kit ligand) were transduced with the N2 retroviral vector containing the neomycin resistance (neor) gene. More than 80% of transduced HPCs were resistant to the toxic G418 level. Thereafter, the HPCs were effectively transduced with the LNSN retroviral vector containing a nerve growth factor receptor complementary DNA; the nerve growth factor receptor was detected on > or = 18% of the transduced HPCs. These experiments provide a new tool from which (a) to monitor expression of a transduced membrane report on hematopoietic cells, particularly at the level of HPCs/HSCs, and (b) to characterize the transduced cells by double- and triple-labeling membrane antigen analysis. Purified HPCs/HSCs grown in Dexter-type LTC were transduced at 1 week by exposure to supernatant N2 retroviral particles in the absence of exogenous hematopoietic growth factors. The procedure, devoid of toxic effects, allowed an efficient neor transduction into LTC-ICs. Thus, we consistently detected neomycin-resistant mRNA in the clonal progeny of HPCs produced in LTC at 5-8 weeks in both the nonadherent and adherent fractions; this timing of expression coincides with that of HPC production by LTC-ICs, thereby indicating the effective transduction of the LTC-ICs. These experiments represent a first step toward development of preclinical models for gene transfer into human peripheral blood HSCs by complex retroviral vectors.

Adult↗
PubMed1994

Assessment of cold stress in outdoor work.

The evaluation of cold stress in working life was done in 13, mainly outdoor, occupations and 143 workers using local temperatures, body cooling and thermal sensations. The subjects in the study were young, healthy men and they wore the type of winter clothing generally used in those ambient temperatures (+6...-29 degrees C), for in a work load of from 112 to 480 W. Local temperatures on finger skin indicated that manual dexterity was often reduced in outdoor work. A risk of frostbite was frequently found on the cheek and the wind chill index predicted the risk quite well. Body cooling was often temporarily too high when measured by heat debt and mean skin temperature. Thermal sensations were cool or cold occasionally in 28% of the workers interviewed. The insulation of clothing worn was often lower than the IREQmin-value recommends. The results showed that in outdoor work in winter time cold stress frequently reduced (70%) working ability at least for a short period. Mean skin temperature seems to be, in practice, a useful indicator for body cooling and the IREQmin-value was suitable, especially in light work, to indicate body cooling. A very sensitive factor for the expression of cold stress was finger temperature, at least as an indicator of finger dexterity. Due to the adverse health effects found the cold stress should also be evaluated more systematically in occupational health and safety with health examinations, with protective clothing and technical preventive means.

Adult↗
PubMed1993

Kinematic problems of manipulators for minimal invasive surgery.

The article discusses handling problems in endoscopic surgery and concepts for the augmentation of instrument dexterity. The authors present a kinematic concept for improved surgical tool positioning and orientation. Using a trunk mechanism it is possible to assure augmented dexterity and stiffness for endoscopic handling. The paper addresses the use of steerable endoscopic instruments in a manipulator system for minimal invasive surgery.

Biomechanical Phenomena↗
PubMed1993

A randomized controlled trial of home exercise on the rheumatoid hand.

OBJECTIVE: To study differing home hand exercise interventions to determine effects on grip strength, and secondarily any immediate or short term effects on range of motion, pain, deformities, hand disease activity, and dexterity. METHODS: Randomized controlled trial of 12 weeks of home hand exercise performed for 10-20 min twice daily. Study exercise interventions were range of motion exercises, balanced resistive exercises, and range of motion plus balanced resistive exercises. RESULTS: Aside from transient, mild to moderate discomfort, exercises were well tolerated. Range of motion exercises were associated with improved right hand joint count. Range of motion plus balanced resistive exercises were associated with increased left hand dexterity. Home hand exercise (exercise groups combined) significantly increased left grip strength. CONCLUSIONS: Temporary use of home hand exercise has acceptable side effects and is an effective means of increasing grip strength.

Ambulatory Care↗
PubMed1993

[Arthrodesis of the wrist. Indication, technique and functional consequences for the hand and wrist].

Three studies conducted in our center demonstrated an improved technical success rate and elimination of preoperative pain in patients undergoing wrist fusions, with no significant difference in the ability to perform rapid movements requiring manual dexterity in the course of activities of daily living compared with patients who had undergone motion-preserving limited arthrodeses. The only absolute drawback of wrist fusion is that it obviously does not allow for any wrist motion at all. Limited intercarpal arthrodesis preserves some motion, but according to our results never leads to increased motion postoperatively. Several specific skills were found to present difficulty in patients who had undergone total wrist fusion. These included those requiring volar flexion in a limited space, where it would be difficult to have recourse to compensatory motion imparted by the shoulder and elbow, and those requiring forceful pronation and supination with simultaneous strong grasping. For patients involved in certain occupations requiring fine manual dexterity in tight spaces, wrist fusion might not be the most appropriate procedure. It is interesting that there appears to be a learning curve to the patient's ability to undertake specific activities postoperatively. A strong practice effect is present for the first 3-6 postoperative months, during which time a significant improvement in the patient's overall function is noted. Total wrist arthrodesis gives highly predictable results in the treatment of wrist pain and instability. The ability to perform normal activities of daily living and strenuous manual tasks was comparable to that after alternative motion-preserving procedures. We have not observed improved wrist motion after any wrist motion-preserving procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1996

Antibody ligation of CD9 modifies production of myeloid cells in long-term cultures.

The KMC8.8 monoclonal antibody was made by immunizing rats with the BMS2 stromal cell clone, and was selected for further study because its ability to inhibit production of myeloid cells in Dexter cultures but not that of lymphoid cells in Whitlock-Witte cultures. The influence on myeloid progenitors might have been indirect, since the antibody did not prevent responsiveness to colony-stimulating factors in semisolid agar cultures. Furthermore, there was no inhibition, and some augmentation, of cell production when the antibody was added to established Dexter cultures. A cDNA clone that encoded the KMC8.8-recognized molecule was isolated by expression cloning and found to be identical in sequence to a previously published murine CD9 homologue. The antibody and cDNA clone were used to establish that CD9 is expressed by stromal cells, megakaryocytes, platelets, myeloid cells, and subpopulations of mature lymphocytes in mice. Treatment with the KMC8.8/CD9 antibody slightly augmented adhesion between myeloid cells and stromal cells, consistent with previous reports that this member of the tetraspan family of proteins can transmit proadhesive signals to human platelets and lymphoid cells. CD9 might participate in cell-cell interactions critical for correct orientation and movement of maturing myeloid cells in bone marrow.

Animals↗
PubMed1996

Is there a correlation between mobility of the thumb and mechanical hand function?

Is there a correlation between thumb mobility and mechanical hand function? The metacarpophalangeal mobility, the web, grip force and dexterity were measured on volunteers. Statistical analysis showed a good correlation between the dominant and nondominant hand. Thumb mobility shows no correlation with grip force and dexterity while the width of the webspace has a clear influence on them. We could not find a compensatory mechanism between thumb mobility and the first web.

Adolescent↗
PubMed1996

Diminished autonomic nervous system responsiveness in rheumatoid arthritis of recent onset.

OBJECTIVE: To investigate responsiveness of the autonomic nervous system in rheumatoid arthritis (RA) of recent onset. METHODS: 21 patients (17 women, mean age 55.7 years) and 20 healthy controls (16 women, mean age 52.7 years) were subjected to 4 tasks eliciting divergent autonomic reactions: film watching, mild physical exercise, cognitive discrimination, and the Stroop color-word interference test. Changes in heart rate, diastolic (DBP) and systolic (SBP) blood pressure, and skin conductance relative to pretask baseline values were computed and related to erythrocyte sedimentation rate, pain, mobility, and dexterity. RESULTS: Mean autonomic levels of patients were normal, as well as autonomic responses to film watching and mild physical exercise. Diminished autonomic responses were observed during cognitive discrimination and during the Stroop test. Blood pressure responses were negatively related to pain severity, but positively to impaired dexterity. CONCLUSION: Diminished autonomic nervous system response is observed in RA of recent onset, most clearly in patients with more severe pain. This suggests that it is associated with primary pathophysiological mechanisms.

Adult↗
PubMedDate not supplied

[Comparative study of lipid fraction content in different areas of the rabbit myocardium].

Comparative study of content of main lipid fractions was carried out in five parts of rabbit myocardium by means of thin-layer chromatography on silicagel with subsequent quantitative estimation. Increased concentrations of free and esterified cholesterol, free fatty acids and triglycerides were observed in atrium dextrum and triglycerides in ventriculus dexter as compared with either the corresponding left-side parts of the heart muscle or with septum interventriculare. Content of cholesterol esters, free fatty acids and triglycerides was higher in atrium dextrum as compared with ventriculus dexter. The lowest concentration of phospholipids was approximately the same in other parts of the heart muscle.

Animals↗
PubMedDate not supplied

Repeated neurobehavioral investigations in workers exposed to mercury in a chloralkali plant.

Mercury exposed workers of a chloralkali electrolysis plant were investigated with neurobehavioral methods. At the beginning of the investigation an average exposure of 12 years was stated. Four periods of investigations were carried out over the course of 7 years. A low exposed group (n = 34-50, 21-26 micrograms Hg/l Urine) and a high exposed group (n = 14-21, 111-152 micrograms/l Urine) were defined for each of the time periods using 53 micrograms/l Urine as discriminating level. Controls (n = 37-43) were recruited from non-exposed departments of the factory. Age, verbal intelligence and gender were controlled statistically to reduce potential confounding. Symptoms and personality traits did not covary significantly with the exposure. Finger dexterity, tapping, and aiming were variables out of 13 performance measurements, which showed repeatedly a lower level of performance corresponding with increasing current exposure. However, dose-response relations could not be demonstrated by partial correlations to the concentration of mercury in Urine. Subgroups of 30 controls, 37 low exposed and 14 high exposed workers were examined in a follow-up study with repeated measurements. Significant exposure effects were shown for finger dexterity and aiming.

Adult↗
PubMed1997

Financial and career losses due to rheumatoid arthritis: a pilot study.

OBJECTIVE: To use a novel method of estimating income loss associated with rheumatoid arthritis (RA). METHODS: For the 26 RA patients (16 female and 10 male, mean age 52.77 yrs) participating in our study, job histories were used to estimate earning potential based on the United States Department of Labor job analysis. To estimate current function, work samples were performed using the Valpar Instrument Battery. The tests include measures of motor coordination, finger dexterity, and manual dexterity. Databases were used to estimate current earning potential on the basis of these performance measures. RESULTS: Estimated earnings decreased from $18,409 to $13,900 per yr. Furthermore, it was estimated that the number of jobs patients could perform dropped from 11.5 million to 2.6 million. CONCLUSION: These preliminary estimates suggest that RA causes significant reductions in earning potential and in the number of jobs that can be performed. This methodology, using a small sample of patients, produced results consistent with larger population studies.

Arthritis, Rheumatoid↗
PubMed1998

A randomized controlled trial of double-versus single-gloving in vascular surgery.

With the increasing incidence of hepatitis B and HIV, and the increasing awareness of the risk and prevalence of hepatitis C, it is becoming even more necessary to adopt stricter policies to safeguard personnel and to reduce the risk of transmission. Previous studies have shown a need for eye protection, protective clothing and the use of double-gloving during operative or interventional procedures. The risk of infection is much less with unbroken skin and conversely more likely when hollow needles are used. Arguments against the routine use of double-gloving include the loss of dexterity and the discomfort incurred, and the potential loss of dexterity that might theoretically result in more rather than fewer needle-stick injuries.

Gloves, Surgical↗