Extraocular spectral photosensitivity in the tentacles of Hydra vulgaris.

Previous electrophysiological studies on the cnidarian Hydra vulgaris have shown that hydra have a highly developed and specific photoresponse despite their lack of any structure recognizable as a traditional photoreceptor. In an effort to identify the site of hydra's photoreceptors, we recorded extracellularly from single excised tentacles and from ablated hypostomes lacking tentacles in absolute darkness and during exposure to light of various wavelengths. During recording, after an initial period of absolute darkness, tentacles or hypostomes were exposed to light from 450nm to 600nm, red, and white light. Exposure to light caused a change in the pattern and frequency of impulses in the tentacles that varied with color. The number of large tentacle pulses (TPs) increased at 550 and 600nm relative to darkness, whereas the number of small tentacle pulses (STPs) tended to decrease in 500nm light. Impulse frequency was significantly different among the different wavelengths. In addition to bursts of tentacle contraction pulses, long trains of pulses were observed. A change in lighting caused a switch from bursting to trains or vice versa. In contrast to excised tentacles, no change in electrical activity was seen in ablated hypostomes at any of the wavelengths relative to each other or relative to darkness. These results indicate that isolated tentacles can distinguish among and respond to various colors across the visible spectrum and suggest that electromagnetic information is transmitted from the tentacles to the hypostome where it may be integrated by the hypostomal nervous system, ultimately contributing to hydra's photoreceptive behavior.

Evaluation of health and safety risks in municipal solid waste recycling plants.

Designers and managers of recycling processing plants need to be informed about the inherent occupational health and safety risks; however, there are few studies in the literature describing these risks. Therefore, the objectives of this project were to document the biological, chemical, physical, and ergonomic risks in three household-waste recycling plants. Bioaerosols (molds and bacteria) were measured using the methodology recommended by the American Society for Testing and Materials (ASTM). Chemical contaminants and physical agents suspected of being present in this type of environment were measured using the standard methods of the Quebec Occupational Health and Safety Research Institute (IRSST). The ergonomic part of the study identified the work requirements and risk factors causing the workers' physical symptoms. In summer, the average concentrations of total bacteria were greater than the Scandinavian guideline of 10,000 colony forming units per cubic meter of air (CFU/m3) in the receiving areas in plants 1 and 3, in the sorting areas of the three plants, and in shipping in plants 1 and 3. When the average concentrations of gram-negative bacteria were compared to the Scandinavian guideline of 1000 CFU/m3 of air, only the sorting department in plant 2 in summer exceeded this value. Average indoor concentrations of molds that were statistically significantly greater than those measured in the upwind outdoor air were measured in all departments in plants 1 and 3, regardless of the season, and only in sorting in plant 2 during the summer. The only chemical contaminant measured at average concentrations greater than 50% of the Threshold Limit Values (TLVs) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH) was CO in the sorting departments in plants 1 and 2 during the winter. Noise exceeded the ACGIH TLV in plant 2. The workers' physical symptoms seem to be caused by the posture and effort required while remaining in a stationary position. Action must be focused on improving aspects such as work organization and personal protection and on informing citizens of the need for cleanliness of the material to be recycled.

Aging and shiftwork: the effects of 20 years of rotating 12-hour shifts among petroleum refinery operators.

The survey was conducted in a Canadian refinery where operators have been working rotating 12-hour shifts for 20 years. A multidisciplinary approach was adopted, based on 12 sources of data. Descriptive statistics and chronoergonomic observations were used. The most marked consequences of the schedule were observed among former shiftworkers. Among current shift workers, sleep deficit, chronic fatigue, health problems, and disruption of social and family life were the most serious effects observed. Aging and under-staffing, however, interact with schedule by necessitating overtime and reducing the actual number of rest days, which in turn affects fatigue and reliability. In the near future, the low replacement rate of the workforce and the limitations on reassignment of aging workers to day shifts will probably prevent the selection process from playing its "protective" role. Besides, with the 5-year delay of the retirement age, the harmful effects in older operators active over the next 5-10 years may prove greater than those observed in this study.

Cardiopulmonary compromise after use of topical and submucosal alpha-agonists: possible added complication by the use of beta-blocker therapy.

We report the specifics of 12 cases of severe hypertension after the intraoperative use of topical phenylephrine, submucosal epinephrine, or both. Ten of these 12 patients also developed severe pulmonary edema. Seven of the twelve were treated with beta blockers; 3 of whom suffered cardiac arrest. We propose a common mechanism: the vasoconstrictors caused systemic hypertension, increased left ventricular afterload, decreased left ventricular compliance, and decreased cardiac output. In those patients treated with beta blockers, decreased contractility and inability to increase heart rate further compromised cardiopulmonary function.

Tantalum balloon-expandable stent: in vivo swine studies.

PURPOSE: The authors describe the experimental use of a balloon-expandable tantalum vascular stent in normal and atherosclerotic microswine. MATERIALS AND METHODS: Thirty-one stents (15 iliac, 13 aorta, two femoral, one renal) were placed in 11 animals. Stents were placed in both normal and stenotic atherosclerotic arteries. The animals were killed and the stents explanted 2-32 weeks after placement. Arteriography was performed just prior to death in all cases. RESULTS: All stents were patent arteriographically and on gross inspection. Histopathologic study showed a thin, smooth, endothelial-lined neointima over the segments with stents. This covering had a mean thickness of 2.9 x 10(-5) mm and appeared maximally developed 2-5 weeks after stent placement. The stent design incorporates the following engineering and clinical considerations: minimal profile and surface area and maximal expansion ratio, hoop strength, flexibility, fluoroscopic visibility, biocompatibility, and ease of placement. When compressed and mounted on the balloon catheter, the stent is flexible. This allows it to be easily maneuvered through tortuous or diseased vessels. On expansion, the stent becomes a semirigid tubular structure composed of multiple rhomboid cells. Stents with an expanded diameter of less than 11 mm can be introduced through a 7-F vascular sheath. CONCLUSION: Initial results suggest that this stent successfully incorporates a number of theoretically desirable features for a vascular prosthesis, and it may offer some advantages over previously described devices.

Linear nevus sebaceous syndrome: megalencephaly and heterotopic gray matter.

A 3-month-old white male with linear nevus sebaceous syndrome (LNSS), facial deformities, brain malformations, and cortical blindness is presented. Facial deformities included left ear hypertrophy and a left-sided hamartomatous neck mass. Magnetic resonance imaging suggested that a central nervous system (CNS) abnormality, involving gray and white matter, should be linked with LNSS. Magnetic resonance imaging was more useful than computed tomography in demonstrating the full spectrum of CNS anomalies, including unilateral lissencephaly, a paucity of white matter, excessive and heterotopic gray matter, apparent left schizencephaly, and unilateral left colpocephaly (dilation of atrium and posterior horn of lateral ventricle). Postmortem examination revealed left hemisphere megalencephaly with a dilated posterior horn of the lateral ventricle. The impressive gray matter heterotopias likely were the source of the patient's seizures and perhaps the ultimate cause of death. Megalencephaly and other deviations of neuronal migration should be considered as a dramatic component of LNSS.

Cerebrospinal fluid shunts. Evaluation, complications, and crisis management.

This article describes commonly used shunt systems and the simple methods that can be used to identify them. Evaluation of shunt system function, definition of site of shunt dysfunction, and immediate intracranial decompression therapy are discussed. Other complications of CSF shunt therapy and their treatments are also presented.

Traumatic rupture of right mainstem bronchus in a child.

We report a case of a 7-year-old boy who sustained a ruptured right mainstem bronchus in a motor vehicle accident. The clinical presentation, pathophysiology, and diagnosis of tracheobronchial injuries secondary to nonpenetrating thoracic trauma are discussed.

Toxic-shock syndrome associated with nasal packing: analogy to tampon-associated illness.

A pure culture of migmatoxin-producing Staphylococcus aureus was isolated from the purulent nasal packing removed from a 13-year-old premenarchal girl with toxic-shock syndrome after rhinoplasty. The similarities between this case and the tampon-associated illness are examined. An increased awareness of these similarities and the identification of predisposing factors may lead to earlier detection and treatment of toxic-shock syndrome.

Intracranial volume pressure response in infants and children: preliminary report of a predictive marker in metabolic coma.

Intracranial volume-pressure response was assessed in 6 children suffering from metabolic coma and ranging in age 2 months-13 years. No untoward pressure or infectious complications occurred. The relationship between baseline mean intracranial pressure (MICP) and volume-pressure response assessment (VPRA) in these patients seems to be exponential rather than linear. By itself, the test is no better than baseline MICP at identifying patients at greatest risk of developing significantly increased intracranial pressure (ICP). When used in conjunction with baseline MICP, this method of VPRA identifies a population with an 80% risk of developing serious ICP elevations within a 4 h time period. Patients with best overall prognosis had significantly lower mean VPRA values than those with poorest overall prognosis.