Traumatic anterior shoulder instability.
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Arthroscopy↗
Biomedical subjects
B S Cohen
Publications and source records attributed to B S Cohen.
Detecting H+ in ultrafine ambient aerosol using iron nano-film detectors and scanning probe microscopy.
Recent epidemiological evidence strongly suggests that ambient-particle-associated acidity is more closely correlated with total mortality and hospital admissions for respiratory disease than indices of total particulate mass. In addition, evidence is accumulating to support the hypothesis that the number of ultrafine (d < or = 200 nm) acid particles, rather than ambient mass, is an important determining factor affecting lung injury. Both outdoor and indoor air environments are dominated by nanometer-sized particles. However, no data are currently available on the size distribution or number concentration of acidic ambient ultrafine particles largely because there are no suitable methods for measuring these important quantities. We have developed a method to accomplish these measurements based on the use of iron nano-films for detection of acid droplets. Detectors were prepared by vapor deposition of iron onto 12-mm-diameter glass cover slips. The detectors develop reaction sites when exposed to H2SO4 or NH4HSO4 particles. Exposures to non-acidic particle (NaCl and [(NH4)]2SO4) result in no detectable surface deformations. The nano-films are examined with scanning probe microscopy (SPM) for the enumeration of reaction sites. Until recently, direct visualization of individual objects smaller than 200 nm has been possible only with electron microscopy. The advancement of SPM provides the opportunity to examine the detector surface features with high quality three dimensional imaging.
Aerosols↗
Breathing zone concentration variations in the reinforced plastic industry; field measurements in a boat manufacturing plant.
Breathing zone samples are used to estimate worker exposure to airborne contaminants by collecting air from a vaguely defined zone surrounding the head. This zone is considered to have an airborne chemical concentration equivalent to the concentration breathed by the worker. It has been generally assumed that vapor is uniformly mixed in the breathing zone; therefore, samplers are placed on either lapel or on the chest of the worker. An extensive field investigation in a boat manufacturing plant was conducted where styrene air concentrations were measured by mounting four 3M one-stage diffusion samplers around the worker's breathing zone. Two job classes were studied: the spray gun operators and the rolling and tucking operators. Styrene air concentrations detected at the nose were significantly different than those concentrations detected at the other three locations and represented 90 percent, 84 percent, and 76 percent of the left lapel, right lapel, and chest samplers, respectively. This research revealed that the chest sampler provides a consistent relationship to the concentrations measured at the nose for a given job category. Additionally, this research identified the possible factors which could contribute to breathing zone concentration variations.
Air Pollutants, Occupational↗
A portable vapor/particle sampler.
The airborne particle and vapor phases of a volatile organic chemical (VOC) often coexist in the real workplace environment. Assessment of worker exposure to a VOC requires measuring not only the total airborne concentration but also the phase distribution because the deposition efficiency of the material in the respiratory tract will depend on the form in which it is inhaled. A prototype portable vapor/particle sampler (PVPS) has been designed for sampling and quantifying the phase distribution of volatile components in micrometer-sized airborne particles and coexisting gaseous phase based on differential inertia. The sampler was laboratory tested and validated. Tests included sampler performance assessment and comparison with current sampling methods for particles and organic vapors, i.e., glass fiber filter, charcoal sorbent tube, and diffusion monitors. The PVPS is a low-cost and lightweight device that can be driven by a single standard personal sampling pump. The mass quantities of materials collected by the sampler can be determined by standard analytical procedures. Combined with an appropriate size-selective inlet, the PVPS may be used as a personal inhalable or respirable volatile aerosol sampler for occupational VOC exposure assessment, especially in industrial, or household, spray work environments where the particle sizes are frequently large.
Aerosols↗
Deposition of charged particles on lung airways.
The effect of a single electric charge on the efficiency with which ultrafine particles deposit in human airways has been investigated. When inhaled short-lived radon progeny are attached to electrically neutral particles their deposition efficiency is controlled by diffusion. But most ambient particles carry one, or a few, charges. We measured and compared the deposition (DE) of singly charged, charge-neutralized, and zero-charge 20-nm and 125-nm particles in hollow-cast models of human airways. These particle sizes were selected because they are about where modal peaks occur for the activity of the short-lived radon progeny in indoor air. For singly charged 20-nm particles deposition (+/- standard error) in the casts was 3.4 +/- 0.3 times that for charge neutralized aerosols and 5.3 +/- 0.3 times the amount deposited for zero-charged particles. Corresponding ratios for the 125-nm particles were 2.3 +/- 0.3 and 6.2 +/- 0.7. Since most ambient particles are charged this effect must be considered when models are used to predict dose from inhaled ultrafine particles.
Adult↗
Effects of caffeine ingestion on endurance racing in heat and humidity.
A hot and humid environment can be detrimental to race performance. Caffeine, on the other hand, has been shown to be an ergogenic aid for improving endurance performance. To examine the influence of caffeine ingestion on race performance during high heat stress, seven endurance trained competitive road racers aged between 23 and 51 years (five men, two women) performed three maximal effort 21-km road races outdoors in hot and humid conditions. The caffeine dose, randomly assigned in a double-blind fashion, consisted of either 0, 5, or 9 mg.kg-1 body mass. During each run, the subjects were allowed to drink water ad libitum at each 5-km point. Blood samples were obtained immediately before and after each run and analysed for changes in concentrations of Na+, K+, glucose, lactate, and hematocrit. Pre and postrun data were also collected for body mass and tympanic membrane temperature. Race times were not significantly different among the races or caffeine doses, with the average times within 1.1% of each other. In addition, none of the other variables measured varied significantly among the races or caffeine doses. In summary, caffeine intake did not affect race performance. Therefore it was concluded from our study that caffeine is not of ergogenic benefit in endurance races during high heat stress.
Adult↗
Particle deposition in human and canine tracheobronchial casts: a determinant of radon dose to the critical cells of the respiratory tract.
The radiation dose to the sensitive cells of the bronchial epithelium from inhaled short-lived radon progeny depends critically on the efficiency with which the particles are deposited on the airway surfaces. Measurements of deposition for particles 50, 100, 180, and 400 nm in diameter have been carried out along three single pathways in full hollow airway casts of the human and canine tracheobronchial trees. The pathways are a major branch path, a minor branch path, and one which consists of alternating major and minor branches. The casts, prepared from whole lungs obtained at autopsy, extend to airways with diameters less than 1 mm. Monodisperse test aerosols were nebulized from either a 99mTc-ferric oxide or 99mTc-NaCl solution and size classified with an electrostatic classifier or formed by condensation of triphenyl phosphate onto 99mTc-salt nuclei. Measured deposition fractions (etaFs) form a family of curves with etaF being highest for the 50 nm particles and lowest for 400 nm. This agrees with expectations for this particle size range where diffusion is the dominant deposition mechanism. The etaF pattern is strongly influenced by the morphometry and resulting airflow distribution. Results of the experiments obtained in the human cast are compared with two predictive deposition models. The model, that is more explicit with respect to flow and geometric parameters, appears to be a marginally better predictor of the data.
Animals↗
Race and physical activity: cardiovascular and renal response to sodium loading.
Race and level of physical activity may be important factors affecting cardiovascular responsiveness to acute sodium intake. We examined the effects of a 4-day sodium loading procedure on heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure, 24-hour electrolyte excretion, and extracellular fluid volume (ECF) in African-American (n = 16) and Caucasian (n = 16) adult males. All subjects were normotensive with either moderately high (> or = 3 day/wk; > or = 20 min/day) or low (< or = 3 day/wk; < or = 20 min/day) physical activity levels. Subjects ingested either placebo or NaCl (0.2 g/kg/day) during two 4-day periods. Sodium loading increased SBP and decreased HR in all high physical activity subjects but not in low physical activity subjects (p < 0.05). Na+ excretion did not differ among groups, although urine volume and K+ excretion were lower, and Na+/K+ excretion ratio was higher in African-American compared to Caucasian subjects (p < 0.05). ECF, as measured by NaBr dilution, was greater in high physical activity subjects compared to low physical activity subjects (p < 0.05). These data suggest that high physical activity levels do not attenuate but rather exaggerate SBP response to a sodium load.
Adult↗
A simple method for vapor dosing of charcoal sorbent tubes.
A method for vapor-dosing of charcoal sorbent tubes (CST) that does not require the expense and effort of a test chamber was used to test the desorption efficiency (DE) of seven solvent vapors, representing six classes of solvents as follows: aromatic hydrocarbons (m-xylene); ether/alcohol (2-ethoxyethanol); vinyl monomers (styrene monomer, vinyl acetate); aliphatic hydrocarbons (n-hexane); aliphatic esters (n-butyl acetate); and aliphatic acrylic monomers (methyl methacrylate). The quantities of the solvents used in these experiments would represent eight-hour exposures to concentrations of approximately 0.2 to 10 ppm. The vapor-dosing experimental system consisted of a loaded filter cassette connected directly to a CST. Vapor was generated by injecting liquid solvent onto the glass fiber filter and drawing air through the system. The solvent was desorbed from the filter and charcoal for analysis. Vapor desorption efficiency was determined from the fraction of the injected solvent evaporated from the filter and the amount recovered from the charcoal. The measured DEs were similar to those reported for liquid dosed charcoal. Vapor dosing of sorbent tubes is more representative of samples collected for industrial hygiene exposure assessment. The system is simple to use and applicable for vapor dosing of any sorbent tube.
Atmosphere Exposure Chambers↗
Factors affecting distribution of airflow in a human tracheobronchial cast.
Air velocity was measured at end airways of hollow replicate casts of the human tracheobronchial tree in order to determine the flow distribution within casts extending to 3 mm diameter airways. Measurements were made by hot-wire anemometry for constant inspiratory flow rates of 7.5, 15, 30 and 60 L.min-1. Average flow distribution among the lung lobes was as follows: right upper, 18.5%; right middle, 9.2%; right lower, 32.3%; left upper, 15.7%; and left lower, 24.3%. An empirical model derived from the experimental flow distribution data demonstrated the effect of various morphometric parameters of the hollow cast on the distribution of airflow. Airway cross-sectional area, branching angle and total path-length were found to have the greatest influence. As the tracheal flow rate decreased from 60 to 7.5 L.min-1, the influence of branching angle was reduced, while total path-length became more influential. These results provide evidence for the transition of flow regimes within the TB tree within normal physiological flow ranges.
Adult↗
Relationship between anxiety disorders and depressive disorders in patients with cerebrovascular injury.
The interaction between anxiety disorder and major depressive disorder in patients with cerebrovascular lesions was examined in a controlled, 2 x 2 study design. A consecutive series of 24 patients who met criteria for major depression only were compared with 6 patients who met criteria for both major depression and generalized anxiety disorder, and 45 patients who did not meet criteria for either major depression of generalized anxiety. Among patients with positive computed tomographic scans, the anxious-depressed group (n = 19) showed a significantly higher frequency of cortical lesions, while patients with major depression only (n = 15) had a significantly higher frequency of subcortical (basal ganglia) strokes. No significant between-group differences were found in other variables, such as demographic variables, familial and personal history of psychiatric disorders, and neurologic deficits. These findings suggest that, in this mostly black, low-socioeconomic-status population, cortical vs subcortical lesion location may play an important role in determining whether severe anxiety occurs in patients with post-stroke major depression.
Anxiety Disorders↗
A method for monitoring dermal exposure to volatile chemicals.
Absorptive pads of charcoal cloth were developed and tested for monitoring the deposition of volatile toxic materials on skin. The dosimeters can retain over 60% of volatile deposits such as toluene or dichloropropene droplets over an 8-hr workday. Evaporation from liquid deposits and vapor adsorption onto the dosimeters are factors which can complicate the interpretation of exposure data. Evaporation was inversely proportional to the log of the deposit size (volume), vapor pressure, and the air humidity. Vapor adsorption was proportional to the vapor concentration, exposure duration, and the log of air velocity. A procedure is offered for estimating the initial size of the liquid deposit from retained mass. The charcoal cloth dosimeter's accuracy and precision are optimal in situations involving possible dermal exposure to toxic materials with low to moderate volatility or with low vapor concentration, i.e., those where dermal exposure may be equal to or more significant than respiratory exposure.
Adsorption↗
Flow distribution in human and canine tracheobronchial airway casts.
Measurements of flow rates through hollow casts of human and canine tracheobronchial airways, which extend from just below the larynx to airways 1 mm in diameter, show basic similarities in the distribution of air flow and also species differences which must be considered. The distribution of air flow, for both constant and pulsatile inspiratory flow, was measured for minute volumes equivalent to 6, 11, 17 and 22 L min-1 for the human and 3, 6, 8, and 11 L min-1 for the dog. Inertia of air flow (inertance) was found to carry more of the flow to airways of the lower lobes at higher flow rates. Basic differences in airway branching pattern result in a more distinct change in airflow distribution as flow rate changes for the canine cast as compared with the human cast. These differences should contribute to differing patterns of mass transfer of inhaled particles and gases in central airways of the two species.
Animals↗
Flow distribution through human and canine airways during inhalation and exhalation.
Airflow distribution through the tracheobronchial tree is influenced by many factors. In a hollow cast of the central airways, the only factors involved are resistance and inertia of the airflow. Distribution of steady flow during both inhalation and exhalation was measured at different total flow rates in human and canine tracheobronchial casts. The resulting airflow rates in peripheral segments were measured with a sensitive apparatus, which did not disturb the distribution of flow. Inertia of the airflow was found to be small but significant in airways of the human cast and substantially greater in the canine airway cast than in the human cast during inhalation. The influence of airflow inertia during inhalation was largely responsible for the different distributions of flow during inhalation and exhalation through the airway casts. Airflow resistance was found to be considerably greater during exhalation and may have contributed to the redistribution of flow. The forces involved are small but should be considered when modeling the in vivo distribution of airflow.
Airway Resistance↗
Antipanic drug effects during lactate infusion in lactate-refractory panic patients.
In previous articles we have reported on the total Acute Panic Inventory (API) score during lactate-induced panic. Even patients with panic disorder who do not panic during lactate infusion have higher API scores during the infusion than normal controls. In this post hoc analysis, we wished to determine whether specific API items were more sensitive to the beneficial effects of antipanic medication, either at baseline or during the infusion, in these lactate-insensitive panic patients. Four of the 17 items showed specific drug blockade of baseline severity. Five additional items showed specific drug blockade of lactate exacerbation of symptom severity. Medication apparently had no effect on severity of the remaining eight items. We suggest that the nine symptoms that responded to drug therapy are associated with hyperventilation. The study indicates that antipanic drugs may have a specific effect in blunting hyperventilation.
Adult↗
Industrial hygiene protection for the podiatric physician.
The podiatrist should remain alert to the potential for exposure to hazardous agents such as those discussed in this article. Exposures in the office or hospital may be evaluated by the methods of industrial hygiene. If control is needed, simple measures can frequently effect substantial reduction in exposure and afford protection to the physician, staff, and patient.
Air Pollutants, Occupational↗
Blood gas changes and hypophosphatemia in lactate-induced panic.
Alkalosis is prominent among the many physiologic and biochemical effects of sodium lactate infusion. Though this is partially due to the conversion of lactate to bicarbonate, the metabolic component, it may also be secondary to hyperventilation before and during the infusion, the respiratory component. We analyzed pH, carbon dioxide pressure, bicarbonate, and inorganic phosphate from patients with panic disorder and agoraphobia with panic attacks and from normal controls both before and during lactate infusion. Our findings extend earlier work demonstrating that many such patients are chronic hyperventilators. Both metabolic and respiratory alkalosis develop in all subjects during lactate infusion, but only hyperventilation-induced hypocapnia differentiates patients at the point of lactate-induced panic from nonpanicking patients and normal controls. Finally, low inorganic phosphate levels at baseline appear associated with patients who will panic during the subsequent lactate infusion. This last unexpected finding may reflect hyperventilation or an abnormality in intracellular glycolysis.
Adult↗
Resuspension of dust from work clothing as a source of inhalation exposure.
Workshirts which had been worn by employees at a beryllium refinery were tested to assess whether wear significantly affects the amount of resuspended Be containing dust. Sections of six work shirts--three "new" (one washed, two unwashed) and three "old" (one washed, two unwashed)--were analyzed to measure the concentration of Be in the fabric. Additional swatches were agitated to resuspend Be particles inside a closed steel glove box. Air samples were taken with filter cassette monitors. After sampling, the fabric and filter samples were analyzed for beryllium. As a group, the old shirts resuspended significantly higher quantities of Be to the air than did the washed and unwashed new shirts. A considerable fraction of the Be measured in air was respirable.
Air↗