Quantifying repetitive hand activity for epidemiological research on musculoskeletal disorders--part I: individual exposure assessment

An exposure measurement approach is described for quantifying repetitive hand activity of individual workers in a prospective epidemiological study on work-related upper extremity musculoskeletal disorders. A total of 733 subjects were involved in this study at the baseline. Hand activities were quantified by force and repetition. Force levels were measured by workers' self-reports, ergonomists' estimates based on observation and measurements with instrumentation. Repetition levels were measured by detailed time-motion analyses using two repetitive hand activity definitions and ergonomists' estimates using scales for the American Conference of Governmental Industrial Hygienists hand activity level and the Strain Index. Results showed that the present exposure assessment approach seems to be able to quantify force level and repetitiveness of hand activities. Repetitive hand activity is quantified differently depending on whether forceful hand exertion or repetitive muscle activity is used as the definition. These hand activity definitions may quantify different physical exposure phenomena. Individual exposure assessment is important in epidemiological research of musculoskeletal disorders as there are interactions between the individual subjects and the measured parameters. These interactions may vary between exposure parameters.

Quantifying repetitive hand activity for epidemiological research on musculoskeletal disorders--part II: comparison of different methods of measuring force level and repetitiveness

This paper focuses on comparisons between the different methods of assessing repetitive hand activities. Various methods were used to measure hand force and repetitiveness of hand activities on 733 subjects in the study described by Bao et al. (2006). Two definitions of repetitiveness were used in analysis of detailed time studies of repetitive hand activities and four parameters of the American Conference of Governmental Industrial Hygienists (ACGIH) hand activity level (HAL) and the Strain Index methods were estimated by ergonomists and used to quantify repetitiveness. Hand forces were measured or estimated using three different methods: 1) measured with a force gauge or mimicked on a force gauge (force matching); 2) estimated by ergonomists using rating scales; 3) self-reports by subjects. The jobs were also evaluated using the ACGIH HAL and Strain Index methods when different repetitiveness quantification methods were used. Results showed that different definitions of repetitive exertion might lead to measuring different physical exposure phenomena and produce very different results. There were poor correlations between the measures of repetitiveness estimated by the different methods. Correlations between force quantifications using different methods were also poor. This suggests that parameters measured by different methods might not be interchangeable. Both the ACGIH HAL and Strain Index methods identified more 'hazardous' jobs when repetitiveness was estimated by ergonomists than when it was calculated by detailed time studies of forceful hand exertions. The Strain Index method identified more 'hazardous' jobs than the ACGIH HAL method. Overall, the between-methods agreements were found to be moderate to substantial.

Compensation in pre-synaptic dopaminergic function following nigrostriatal damage in primates

Clinical symptoms of Parkinson's disease only become evident after 70-80% reductions in striatal dopamine. To investigate the importance of pre-synaptic dopaminergic mechanisms in this compensation, we determined the effect of nigrostriatal damage on dopaminergic markers and function in primates. MPTP treatment resulted in a graded dopamine loss with moderate to severe declines in ventromedial striatum (approximately 60-95%) and the greatest reductions (approximately 95-99%) in dorsolateral striatum. A somewhat less severe pattern of loss was observed for striatal nicotinic receptor, tyrosine hydroxylase and vesicular monoamine transporter expression. Declines in striatal dopamine uptake and transporter sites were also less severe than the reduction in dopamine levels, with enhanced dopamine turnover in the dorsolateral striatum after lesioning. The greatest degree of adaptation occurred for nicotine-evoked [(3)H]dopamine release from striatal synaptosomes, which was relatively intact in ventromedial striatum after lesioning, despite > 50% declines in dopamine. This maintenance of evoked release was not due to compensatory alterations in nicotinic receptor characteristics. Rather, there appeared to be a generalized preservation of release processes in ventromedial striatum, with K(+)-evoked release also near control levels after lesioning. These combined compensatory mechanisms help explain the finding that Parkinson's disease symptomatology develops only with major losses of striatal dopamine.

Overexpression of RAN1 in rice and Arabidopsis alters primordial meristem, mitotic progress, and sensitivity to auxin

Ran is an evolutionarily conserved eukaryotic GTPase. We previously identified a cDNA of TaRAN1, a novel Ran GTPase homologous gene in wheat (Triticum aestivum) and demonstrated that TaRAN1 is associated with regulation of genome integrity and cell division in yeast (Saccharomyces cerevisiae) systems. However, much less is known about the function of RAN in plant development. To analyze the possible biological roles of Ran GTPase, we overexpressed TaRAN1 in transgenic Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). TaRAN1 overexpression increased the proportion of cells in the G2 phase of the cell cycle, which resulted in an elevated mitotic index and prolonged life cycle. Furthermore, it led to increased primordial tissue, reduced number of lateral roots, and stimulated hypersensitivity to exogenous auxin. The results suggest that Ran protein was involved in the regulation of mitotic progress, either in the shoot apical meristem or the root meristem zone in plants, where auxin signaling is involved. This article determines the function of RAN in plant development mediated by the cell cycle and its novel role in meristem initiation mediated by auxin signaling.

Evaluation of clinical and serological data from Taenia solium cysticercosis patients in eastern Inner Mongolia Autonomous Region, China

Neurocysticercosis (NCC) is one of the major causes of neurological disease in China. ELISA and immunoblotting using glycoproteins purified by preparative isoelectric focusing were used to detect human cysticercosis in Tongliao area, Inner Mongolia, China in 1998. Approximately 89% (39 of 44 inpatients and outpatients with suspected NCC at Tongliao City Hospital) were residents of Inner Mongolia. About 53% were male and 77% were of working age (18-59 years), and 32% were farmers. Immunoblotting and ELISA showed a high correlation. Of the 44 patients, 31 positive by cerebral computed tomography (CT) scan were confirmed serologically to have cysticercosis. In the ELISA, patients with no lesions by CT scan had lower OD values, similar to those of normal serum. These findings confirm that both ELISA and immunoblotting assays are sufficiently sensitive to detect asymptomatic or symptomatic cysticercosis patients.

Disruption of the Rad9/Rad1/Hus1 (9–1–1) complex leads to checkpoint signaling and replication defects

The checkpoint sliding-clamp complex, Rad9/Rad1/Hus1, plays a critical role during initiation of checkpoint signals in response to DNA damage and replication disruption. We investigated the impact of loss of Rad1 on checkpoint function and on DNA replication in mammalian cells. We show that RAD1 is an essential gene for sustained cell proliferation and that loss of Rad1 causes destabilization of Rad9 and Hus1 and consequently disintegration of the sliding-clamp complex. In Rad1-depleted cells, Atr-dependent Chk1 activation was impaired whereas Atm-mediated Chk2 activation was unaffected, suggesting that the sliding clamp is required primarily in Atr-dependent signal activation. Disruption of sliding-clamp function also caused a major defect in S-phase control. Rad1-depleted cells exhibited an RDS phenotype, indicating that damage-induced S-phase arrest was compromised by Rad1 loss. Furthermore, lack of Rad1 also affected the efficiency of replication recovery from DNA synthesis blockage, resulting in a prolonged S phase. These deficiencies may perpetually generate DNA strand breakage as we have found chromosomal abnormalities in Rad1-depleted cells. We conclude that the Rad9/Rad1/Hus1 complex is essential for Atr-dependent checkpoint signaling, which may play critical roles in the facilitation of DNA replication and in the maintenance of genomic integrity.

IkappaB kinase promotes tumorigenesis through inhibition of forkhead FOXO3a

Nuclear exclusion of the forkhead transcription factor FOXO3a by protein kinase Akt contributes to cell survival. We investigated the pathological relationship between phosphoylated-Akt (Akt-p) and FOXO3a in primary tumors. Surprisingly, FOXO3a was found to be excluded from the nuclei of some tumors lacking Akt-p, suggesting an Akt-independent mechanism of regulating FOXO3a localization. We provide evidence for such a mechanism by showing that IkappaB kinase (IKK) physically interacts with, phosphorylates, and inhibits FOXO3a independent of Akt and causes proteolysis of FOXO3a via the Ub-dependent proteasome pathway. Cytoplasmic FOXO3a correlates with expression of IKKbeta or Akt-p in many tumors and associates with poor survival in breast cancer. Further, constitutive expression of IKKbeta promotes cell proliferation and tumorigenesis that can be overridden by FOXO3a. These results suggest the negative regulation of FOXO factors by IKK as a key mechanism for promoting cell growth and tumorigenesis.

Microsatellites in starch-synthesizing genes in relation to starch physicochemical properties in waxy rice ( Oryza sativa L.)

Rice starch is composed of amylose and amylopectin. Amylose content, an important determinant of rice starch quality, is primarily controlled by the waxy gene, encoding granule-bound starch synthase (GBSS). The starch branching enzyme (SBE) and soluble starch synthase (SSS) play major roles in the synthesis of amylopectin. Microsatellite polymorphisms in the three genes, the wx gene encoding granule-bound starch synthase I, the SBE gene encoding starch branching enzyme I and the SSS gene encoding soluble starch synthase I, were studied for 56 accessions of waxy rice ( Oryza sativa L.). Four (CT)(n) microsatellite alleles, (CT)(16), (CT)(17), (CT)(18) and (CT)(19), at the wx locus were detected in this set of waxy rice, of which (CT)(17) was the most frequent. Three (CT)(n) microsatellite allele classes were found at the SBE locus, (CT)(8) or (CT)(10) together with an insertion sequence of CTCTCGGGCGA, and (CT)(8) alone without the insertion. There were multiple microsatellites clustered at the SSS locus. However, these alleles can also be grouped into three classes, i.e. the allele class SSS-A = (AC)(2) em leader TCC(TC)(11) em leader (TC)(5)C(ACC)(11), the allele class SSS-B = (AC)(3) em leader TCT(TC)(6) em leader (TC)(4)C(ACC)(9), and the allele class SSS-C = (AC)(3) em leader TCT(TC)(6) em leader (TC)(4)C(ACC)(8). The analyses of starch physicochemical properties among different microsatellite genotypes indicated that the waxy rice group with the (CT)(19) allele, the SBE-A allele and the SSS-B allele was quite different from other groups. Nine out of 15 accessions with a high gelatinization temperature (GT) belonged to the wx (CT)(19) group, all of them belonged to the SBE-A group and 13 of them belonged to the SSS-B group. These microsatellites might be useful in marker-assisted breeding for the improvement of rice grain quality.

Induction and repair of HZE induced cytogenetic damage

Wistar rats were exposed to high-mass, high energy (HZE) 56Fe particles (1000 GeV/AMU) using the Alternating Gradient Synchrotron (AGS). The animals were sacrificed at 1-5 hours or after a 30-day recovery period. The frequency of micronuclei in the tracheal and the deep lung epithelial cells were evaluated. The relative effectiveness of 56Fe, for the induction of initial chromosome damage in the form of micronuclei, was compared to damage produced in the same biological system exposed to other types of high and low-LET radiation. It was demonstrated that for animals sacrificed at short times after exposure, the tracheal and lung epithelial cells, the 56Fe particles were 3.3 and 1.3 times as effective as 60Co in production of micronuclei, respectively. The effectiveness was also compared to that for exposure to inhaled radon. With this comparison, the 56Fe exposure of the tracheal epithelial cells and the lung epithelial cells were only 0.18 and 0.20 times as effective as radon in the production of the initial cytogenetic damage. It was suggested that the low relative effectiveness was related to potential for 'wasted energy' from the core of the 56Fe particles. When the animals were sacrificed after 30 days, the slopes of the dose-response relationships, which reflect the remaining level of damage, decreased by a factor of 10 for both the tracheal and lung epithelial cells. In both cases, the slope of the dose-response lines were no longer significantly different from zero, and the r2 values were very high. Lung epithelial cells, isolated from the animals sacrificed hours after exposure, were maintained in culture, and the micronuclei frequency evaluated after 4 and 6 subcultures. These cells were harvested at 24 and 36 days after the exposure. There was no dose-response detected in these cultures and no signs of genomic instability at either sample time.

A practical method for ergonomic and usability evaluation of hand tools: a comparison of three random orbital sander configurations

Tool and equipment purchasing decisions are constantly made by companies and workers, often with little objective information beyond word of mouth and marketing information. This study presents a pilot investigation of random orbital sanders using ergonomic and usability assessment techniques which can easily be applied in any industry. Three subjects performed a sanding task using three different tool configurations: 1) the current model sander, 2) current model with hose-swivel attachment, and 3) the new "ergonomically designed" model. Physical measurements were taken of muscle activity and wrist motion to complement think-aloud testing and a usability questionnaire. No significant differences were found in physical measurements between the three configurations. Participants strongly preferred the current model over the new model, reporting less perceived discomfort and vibration, despite what appeared to be improvements in the new design. Workplace changes intended to reduce the risk of injury sometimes may have no effect after significant capital investment, or in some cases even increase the risk of injury. Practical assessment of new tools or modifications can quickly determine whether the outcome is indeed an improvement. The results of this tool assessment highlight the need for objective information in tool and equipment design decisions.

Persistent and specific influences of early acoustic environments on primary auditory cortex

This study demonstrates that the adult form of 'tonotopic maps' of sound frequency in the rat primary auditory cortex (A1) arises from parallel developmental processes involving two cortical zones: the progressive differentiation and refinement of selectively tone-responsive receptive fields within an initially broadly-tuned posterior zone, and the progressive loss of tone-evoked, short-latency response over an initially large, very broadly tuned anterior zone. The formation of tonotopic maps in A1 was specifically influenced by a rat pup's early acoustic environments. Exposure to pulsed tones resulted in accelerated emergence and an expansion of A1 representations of those specific tone frequencies, as well as a deteriorated tonotopicity and broader-than-normal receptive fields. Thus, auditory experiences during early postnatal development are important in shaping the functional development of auditory cortical representations of specific acoustic environments.

The Drosophila double-timeS mutation delays the nuclear accumulation of period protein and affects the feedback regulation of period mRNA

The Drosophila double-time (dbt) gene, which encodes a protein similar to vertebrate epsilon and delta isoforms of casein kinase I, is essential for circadian rhythmicity because it regulates the phosphorylation and stability of period (per) protein. Here, the circadian phenotype of a short-period dbt mutant allele (dbt(S)) was examined. The circadian period of the dbt(S) locomotor activity rhythm varied little when tested at constant temperatures ranging from 20 to 29 degrees C. However, per(L);dbt(S) flies exhibited a lack of temperature compensation like that of the long-period mutant (per(L)) flies. Light-pulse phase-response curves were obtained for wild-type, the short-period (per(S)), and dbt(S) genotypes. For the per(S) and dbt(S) genotypes, phase changes were larger than those for wild-type flies, the transition period from delays to advances was shorter, and the light-insensitive period was shorter. Immunohistochemical analysis of per protein levels demonstrated that per protein accumulates in photoreceptor nuclei later in dbt(S) than in wild-type and per(S) flies, and that it declines to lower levels in nuclei of dbt(S) flies than in nuclei of wild-type flies. Immunoblot analysis of per protein levels demonstrated that total per protein accumulation in dbt(S) heads is neither delayed nor reduced, whereas RNase protection analysis demonstrated that per mRNA accumulates later and declines sooner in dbt(S) heads than in wild-type heads. These results suggest that dbt can regulate the feedback of per protein on its mRNA by delaying the time at which it is translocated to nuclei and altering the level of nuclear PER during the declining phase of the cycle.

Molecular adsorption bond lengths at metal oxide surfaces: failure of current theoretical methods

New experimental structure determinations for molecular adsorbates on NiO(100) reveal much shorter Ni-C and Ni-N bond lengths for adsorbed CO and NH3 as well as NO (2.07, 1.88, 2.07 A) than previously computed theoretical values, with discrepancies up to 0.79 A, highlighting a major weakness of current theoretical descriptions of oxide-molecule bonding. Comparisons with experimentally determined bond lengths of the same species adsorbed atop Ni on metallic Ni(111) show values on the oxide surface that are consistently larger (0.1-0.3 A) than on the metal, indicating somewhat weaker bonding.

Basal forebrain stimulation changes cortical sensitivities to complex sound

Experience affects how brains respond to sound. Here, we examined how the sensitivity and selectivity of auditory cortical neuronal responses were affected in adult rats by the repeated presentation of a complex sound that was paired with basal forebrain stimulation. The auditory cortical region that was responsive to complex sound was 2-5 five times greater in area in paired-stimulation rats than in naive rats. Magnitudes of neuronal responses evoked by complex sounds were also greatly increased by associative pairing, as were the percentages of neurons that responded selectively to the specific spectrotemporal features that were paired with stimulation. These findings demonstrate that feature selectivity within the auditory cortex can be flexibly altered in adult mammals through appropriate intensive training.

Defective gp130-mediated signal transducer and activator of transcription (STAT) signaling results in degenerative joint disease, gastrointestinal ulceration, and failure of uterine implantation

The receptor subunit gp130 transduces multiple cell type-specific activities of the leukemia inhibitory factor (LIF)/interleukin (IL)-6 family of cytokines through the signal transducer and activator of transcription (STAT) and src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2/ras/Erk pathways. To define STAT-dependent physiological responses, we generated mice with a COOH-terminal gp130(DeltaSTAT) "knock-in" mutation which deleted all STAT-binding sites. gp130(DeltaSTAT) mice phenocopyed mice deficient for IL-6 (impaired humoral and mucosal immune and hepatic acute phase responses) and LIF (failure of blastocyst implantation). However, unlike mice with null mutations in any of the components in the gp130 signaling pathway, gp130(DeltaSTAT) mice also displayed gastrointestinal ulceration and a severe joint disease with features of chronic synovitis, cartilaginous metaplasia, and degradation of the articular cartilage. Mitogenic hyperresponsiveness of synovial cells to the LIF/IL-6 family of cyto-kines was caused by sustained gp130-mediated SHP-2/ras/Erk activation due to impaired STAT-mediated induction of suppressor of cytokine signaling (SOCS) proteins which normally limits gp130 signaling. Therefore, the joint pathology in gp130(DeltaSTAT) mice is likely to arise from the disturbance of the otherwise balanced activation of the SHP-2/ras/Erk and STAT signaling cascades emanating from gp130.

Cortical remodelling induced by activity of ventral tegmental dopamine neurons

Representations of sensory stimuli in the cerebral cortex can undergo progressive remodelling according to the behavioural importance of the stimuli. The cortex receives widespread projections from dopamine neurons in the ventral tegmental area (VTA), which are activated by new stimuli or unpredicted rewards, and are believed to provide a reinforcement signal for such learning-related cortical reorganization. In the primary auditory cortex (AI) dopamine release has been observed during auditory learning that remodels the sound-frequency representations. Furthermore, dopamine modulates long-term potentiation, a putative cellular mechanism underlying plasticity. Here we show that stimulating the VTA together with an auditory stimulus of a particular tone increases the cortical area and selectivity of the neural responses to that sound stimulus in AI. Conversely, the AI representations of nearby sound frequencies are selectively decreased. Strong, sharply tuned responses to the paired tones also emerge in a second cortical area, whereas the same stimuli evoke only poor or non-selective responses in this second cortical field in naive animals. In addition, we found that strong long-range coherence of neuronal discharge emerges between AI and this secondary auditory cortical area.

Pattern of cyanophycin accumulation in nitrogen-fixing and non-nitrogen-fixing cyanobacteria

The temporal and spatial accumulation of cyanophycin was studied in two unicellular strains of cyanobacteria, the diazotrophic Cyanothece sp. strain ATCC 51142 and the non-diazotrophic Synechocystis sp. strain PCC 6803. Biochemistry and electron microscopy were used to monitor the dynamics of cyanophycin accumulation under nitrogen-sufficient and nitrogen-deficient conditions. In Cyanothece sp. ATCC 51142 grown under 12 h light/12 h dark nitrogen-fixing conditions, cyanophycin was temporally regulated relative to nitrogenase activity and accumulated in granules after nitrogenase activity commenced. Cyanophycin granules reached a maximum after the peak of nitrogenase activity and eventually were utilized completely. Knock-out mutants were constructed in Synechocystis sp. PCC 6803 cphA and cphB genes to analyze the function of these genes and cyanophycin accumulation under nitrogen-deficient growth conditions. The mutants grew under such conditions, but needed to degrade phycobilisomes as a nitrogen reserve. Granules could be seen in some wild-type cells after treatment with chloramphenicol, but were never found in Delta cphA and Delta cphB mutants. These results led to the conclusion that cyanophycin is temporally and spatially regulated in nitrogen-fixing strains such as Cyanothece sp. ATCC 51142 and represents a key nitrogen reserve in these organisms. However, cyanophycin appeared to play a less important role in the non-diazotrophic unicellular strains and phycobilisomes appeared to be the main nitrogen reserve.

Effects of exogenous interleukin-6 during Pseudomonas aeruginosa corneal infection

Lack of interleukin-6 (IL-6) during Pseudomonas aeruginosa corneal infection leads to more severe disease with changes in neutrophil recruitment. Exogenous IL-6 leads to increased efficiency of neutrophil recruitment and reduced bacterial loads in corneal infection in both IL-6 gene knockout and wild-type mice. This may be mediated by IL-6 increasing the production of corneal macrophage inflammatory protein 2 and intercellular cell adhesion molecule 1. We conclude that effective recruitment of neutrophils into the cornea is dependent on the production of IL-6 and that early augmentation of IL-6 may be protective in corneal infection.

ATR/ATM-mediated phosphorylation of human Rad17 is required for genotoxic stress responses

Genotoxic stress triggers the activation of checkpoints that delay cell-cycle progression to allow for DNA repair. Studies in fission yeast implicate members of the Rad family of checkpoint proteins, which includes Rad17, Rad1, Rad9 and Hus1, as key early-response elements during the activation of both the DNA damage and replication checkpoints. Here we demonstrate a direct regulatory linkage between the human Rad17 homologue (hRad17) and the checkpoint kinases, ATM and ATR. Treatment of human cells with genotoxic agents induced ATM/ATR-dependent phosphorylation of hRad17 at Ser 635 and Ser 645. Overexpression of a hRad17 mutant (hRad17AA) bearing Ala substitutions at both phosphorylation sites abrogated the DNA-damage-induced G2 checkpoint, and sensitized human fibroblasts to genotoxic stress. In contrast to wild-type hRad17, the hRad17AA mutant showed no ionizing-radiation-inducible association with hRad1, a component of the hRad1-hRad9-hHus1 checkpoint complex. These findings demonstrate that ATR/ATM-dependent phosphorylation of hRad17 is a critical early event during checkpoint signalling in DNA-damaged cells.

The presence of functional luteinizing hormone/chorionic gonadotropin receptors in human sperm

The functional receptors that bind human CG (hCG) and LH have recently been identified in a number of nongonadal human tissues. The current experiments tested the hypothesis that human ejaculated sperm may also contain them. The data revealed that they, indeed, do as determined by the presence of receptor messenger RNA and receptor protein that can bind (125)I-hCG. The receptors were functional, as indicated by an increase in cyclic AMP levels and activation of sperm protein kinase A following treatment with hCG or LH. Treatment with these hormones, on the other hand, had no effect on sperm protein kinase C activity. Now that the functional LH/hCG receptors are found in human sperm, it is important to determine whether hCG treatment could improve the outcome of infertility procedures.