Amit Bhattacharya

Nanotube electrodes and biosensors

This article reviews the state of the art in carbon nanotube electrode and biosensor research. Carbon nanotubes have unique mechanical, electrical, and geometrical properties that are ideal for developing different types of nanoscale electrodes and biosensors. Carbon nanotube synthesis and subsequent functionalization strategies to immobilize special biomolecules are discussed first. Then different types of carbon nanotube biosensors and electroanalytical methods are reviewed particularly considering their capabilities for low detection limits, point-of-care applications, and label-free use. Detection strategies for proteins and nucleic acids, as well as mammalian and bacterial cells are also outlined. We conclude with some speculations and predictions on future exciting and challenging directions for nanotube biosensor research and applications.

EFFECT OF WORK LOAN AND RESPIRATOR WEAR ON POSTURAL STABILITY, HEART RATE, AND PERCEIVED EXERTION

The effects on postural stability (sway) were investigated for different work loads under conditions of wearing a full facepiece respirator and not wearing any respiratory protection device. Fifteen subjects accomplished light (40 W), moderate (85 W), and heavy (125 W) work loads under the two conditions. Measurements of postural sway were made immediately after each load by using a multicomponent, strain gage-type force platform. Changes in each subjects movement pattern of the center of pressure were quantitated and compared to their initial baseline sway tests. Each subjects heart rate and perceived exertion were also recorded during each condition. A statistically significant effect (p = 0.007) caused by work load was observed for total length of sway with or without a respirator. An interaction approaching statistical significance (p = 0.056) between work load and respirator use was found. This indicated that sway increased more quickly and in a more consistently linear fashion with increasing work load under the respirator condition (p = 0.02) compared to the nonrespirator condition. The results from the respirator condition showed linear increases in postural sway length across the entire range of work loads, but sway length in the nonrespirator condition showed an increase only at 125-W work loads. The greater increase in sway during the postural balance test could be attributable to the increasing work load-induced proprioceptive fatigue effect on the nervous systems ability to process signals from proprioception systems incongruent with body sway. The heart rate was significantly higher during respirator wear (an increase in heart rate averaging 5.62 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of work related musculoskeletal disorders in active union carpenters.

OBJECTIVES: To determine the prevalence and risk factors for work related musculoskeletal disorders among union carpenters. METHODS: A detailed questionnaire on musculoskeletal symptoms and work history was administered to 522 carpenters. The symptom questions assessed if carpenters experienced pain, numbness, or tingling in a particular body region. A subset of this group then received a physical examination of the upper extremities and knees. RESULTS: The study group was primarily white (94.9%) and male (97.8%) with a mean age of 42.3 years. The highest prevalence of work related musculoskeletal disorders cases by carpentry specialty ranged from 20%-24% for those doing drywall or ceiling, finishing or framing, and the building of concrete forms. Generally, as duration of employment increased, the prevalence of symptoms increased. An adjusted logistic regression analysis showed that the group with the longest (> or = 20 years) duration of employment in carpentry was significantly associated with work related musculoskeletal disorders of the shoulders (odds ratio (OR) 3.2, 95% confidence interval (95% CI) 1.1 to 8.9), hands or wrists (OR 3.1, 95% CI 1.1 to 8.4), and knees (OR 3.5, 95% CI 1.3 to 9.2). Also, analyses showed that carpenters who reported that they had little or no influence over their work schedule had significant increases of work related musculoskeletal disorders of the shoulders, hips, and knees with ORs of 1.9 (95% CI 1.1 to 3.2), 2.9 (95% CI 1.1 to 7.2), and 2.3 (95% CI 1.2 to 4.1), respectively. Feeling exhausted at the end of day was also a significant risk factor for work related musculoskeletal disorders of the knee (OR 1.8, 95% CI 1.1 to 3.1). Upper extremity disorders were the most prevalent work related musculoskeletal disorders reported among all carpenters. Drywall or ceiling activities involve a considerable amount of repetitive motion and awkward postures often with arms raised holding heavy dry walls in place, whereas form work is notable for extensive lumbar flexion and had the two highest rates of work related musculoskeletal disorders. The psychosocial element of job control was associated with both upper and lower extremity disorders. These union carpenters, who were relatively young, already were experiencing considerable work related physical problems. CONCLUSION: This study supports the need for vigilant ergonomic intervention at job sites and early ergonomic education as an integral part of apprenticeship school training to ensure that carpenters remain fit and healthy throughout their working lifetime.

Non-invasive estimation of afferent inputs for postural stability under low levels of alcohol

The maintenance of human equilibrium is a complex process. Several physiological systems provide afferent information for postural stabilization. This study describes a noninvasive methodology to estimate the relative roles of interacting afferent inputs relevant for postural control. A multiaxis force platform in conjunction with specially designed test procedure provided semi-quantitative insight into the roles of vision, proprioceptors and vestibular apparatus in controlling postural sway when it was perturbed by a central nervous system perturbator such as alcohol. Experiments were conducted on 10 male and 10 female subjects. The males did not show statistically significant increases in body sway at these low levels of alcohol. For the females, the present methodology could detect subtle changes in postural sway at low blood alcohol levels ranging between 0.015% and 0.03%. At these low levels of alcohol, the results from females show that when the vision was excluded and the proprioception was modified, the postural sway was most affected. The postural instability experienced in this condition is probably due to inappropriate responses to proprioceptive inputs and lack of vision. Both male and female subjects showed a strong “eyes by standing surface” interaction. The proprioceptor manipulation alone did not affect the postural stability.

Tiny Medicine: Nanomaterial-Based Biosensors

Tiny medicine refers to the development of small easy to use devices that can help in the early diagnosis and treatment of disease. Early diagnosis is the key to successfully treating many diseases. Nanomaterial-based biosensors utilize the unique properties of biological and physical nanomaterials to recognize a target molecule and effect transduction of an electronic signal. In general, the advantages of nanomaterial-based biosensors are fast response, small size, high sensitivity, and portability compared to existing large electrodes and sensors. Systems integration is the core technology that enables tiny medicine. Integration of nanomaterials, microfluidics, automatic samplers, and transduction devices on a single chip provides many advantages for point of care devices such as biosensors. Biosensors are also being used as new analytical tools to study medicine. Thus this paper reviews how nanomaterials can be used to build biosensors and how these biosensors can help now and in the future to detect disease and monitor therapies.

Postural Sway Measurements: A Potential Safety Monitoring Technique for Workers Wearing Personal Protective Equipment

This study investigated the use of postural sway measurements as a potential safety monitoring technique. Sixteen healthy male volunteers (age: 41.8+/-9.3 years) participated in this study. The level of neurophysiological strain and the ability to maintain upright balance for workers wearing personal protective equipment (PPE) were investigated. Three levels of PPE, the United States Environmental Protection Agency (USEPA)-defined levels A, B, and C, were worn in random order while performing two randomly ordered tasks, resting and a workload. After the workload task, the perceived exertion and discomfort were recorded. Postural sway, measured using a microprocessor-based force platform system, was assessed after each task. The variables of sway area and sway length were calculated from stabilograms. These measurements were taken for three sway tests: 1) Eyes open (EO), 2) Eyes closed on a four-inch foam (FC), and 3) a dynamic test with the subject reaching for a weight placed in front, lifting it to his or her chest, and lowering back to the shelf four times (RE). The heart rate was significantly higher for the workload task (p < 0.05), and the levels A and B PPE demonstrated significantly higher perceived exertion results than level C PPE (p < 0.05). The heart rate and perceived exertion were not significantly correlated with the sway measurements. Level A produced significant self-reported discomfort results for the upper back, lower back, and thighs. The sway variables showed significant differences with the PPE levels and the task. The workload task produced significantly higher sway length than the resting task (p < 0.05) for all test conditions. The PPE level B produced significantly higher sway length than PPE level A (p < 0.05) in the FC test condition. These results indicate that postural stability is altered with PPE use and with fatigued postural muscles. In summary, postural sway measurements may be used as a potential safety monitoring technique.

EFFECT OF EARLY LEAD EXPOSURE ON CHILDREN'S POSTURAL BALANCE

This study investigated the effect of chronic exposure to lead on childrens ability to maintain upright postural balance as a biological marker of lead‐induced modifications of the neuromotor system. For this study, 162 six‐year‐old children, with a five‐year geometric mean lead concentration in blood of 11.9μg/dL (range 4.0–28.0μg/dL), were tested for postural balance with a microprocessor‐based force platform system. An increase in blood lead was significantly associated with an increase in the variable postural sway–implying poorer postural balance. This association was not influenced by socio‐economic, racial or environmental factors. This simple, objective and quick technique may be useful for assessing gross motor functions in children who are at or below the United Slates Centers for Disease Controls class III category and/or for monitoring the effectiveness of medical interventions aimed at reversing lead‐associated impairment of upright postural balance.

Postural balance changes in on-duty firefighters: effect of gear and long work shifts.

Objective: The objective of this study was to investigate the impact of long work shifts and turnout gear, including the self-contained breathing apparatus (SCBA) on firefighters’ postural stability. Methods: Sixteen firefighters were assessed using a portable forceplate system at the fire station. Postural sway parameters were recorded at the beginning of the work shift and repeated until the work shift ended. Results: Task had the greatest impact on postural stability for all sway parameters. Turnout gear, with and without SCBA, improved postural stability. Postural stability decreased as firefighters spent more time on duty. Conclusions: Prolonged work shifts may be an important contributor to the high prevalence of slips and falls among firefighters. In all, the results indicate that many aspects of the firefighters’ job may adversely impact their postural stability and potentially increase the risk of falling.

Postural stability assessment in sewer workers

In this study, postural stability was measured with a microcomputer-based force platform as an indirect assessment of central nervous system effect in 28 sewer workers (age range 23.4 to 64.5 years, standard deviation of 8.7 years). All workers performed four 30-second postural sway tests. The organic-solvent exposure was measured by a photo-ionization detector. The photo-ionization detector was calibrated to measure volatile organic solvents in total benzene equivalence, and concentrations were measured in various parts of the plant. The mean exposure was .32 parts per million (ppm) benzene equivalent (range of .02 to .95 ppm, standard deviation .19 ppm). Based on a covariate adjusted linear multiple-regression model, a statistically significant (p < .05) positive correlation was demonstrated between postural sway and organic-solvent exposure. These workers also had increased postural sway compared with a nonexposed population. The statistically significant correlation between postural sway determinations and organic-solvent exposure was surprising given the very low exposures measured. It is possible that the organic-solvent exposure might not be the causative agent, but rather that the solvents themselves correlate with some other causative exposure, ie, total volatile organics as implicated in the cause of sick-building syndrome.

Effect of chronic low level manganese exposure on postural balance: a pilot study of residents in southern Ohio.

Objective:The objective of this study was to determine the effect of non-occupational exposure to manganese (Mn) on postural balance. Methods:Residents living near a ferromanganese refinery provided hair and blood samples after postural balance testing. The relationship between hair Mn and postural balance was analyzed with logistic regression. Following covariate adjustment, postural balance was compared with control data by analysis of covariance. Results:Mean hair Mn was 4.4 &mgr;g/g. A significantly positive association was found between hair Mn and sway area (eyes open on the platform, P = 0.05; eyes closed on the platform, P = 0.04) and sway length (eyes open on the platform, P = 0.05; eyes closed on the platform, P = 0.04). Postural balance of residents was significantly larger than controls in 5 out of 8 postural balance outcomes. Conclusion:Preliminary findings suggest subclinical impairment in postural balance among residents chronically exposed to ambient Mn. A prospective study with a larger sample size is warranted.