[Pain in the legs and progressive neurological deterioration: tethered cord syndrome in adults]. / Pijn in de benen en progressieve neurologische uitval: gekluisterd-ruggenmergsyndroom bij volwassenen.

In four patients, women aged 58, 63 and 42 years, and a man aged 25 years, tethered cord syndrome was diagnosed. These patients suffered from progressive neurological symptoms, notably radiating pain in the legs in the first three patients, and muscle weakness and atrophy in the lower legs in the fourth patient. All four were treated surgically. Nowadays, the phrase tethered (spinal) cord is used for both occult and open closure defects of the neural tube. New neurological symptoms and signs can develop not only in childhood, but also in adults. Neurosurgical release of the tethered cord prevents further deterioration and often leads to significant subjective improvement of symptoms.

Contribution of incidental exposure pathways to total beryllium exposures.

Beryllium manufacturing processes are associated with the immune-mediated chronic beryllium disease (CBO). Recent workplace epidemiological studies have been relatively unsuccessful in correlating disease with workplace air concentrations of beryllium, thereby failing to support the hypothesis that dose by the respiratory route determines the risk of disease. This has led to consideration of the hypotheses that dermal or oral exposures to beryllium can influence disease risk, either as a cause of sensitization or to induced tolerance to beryllium. If so, the control of dermal and/or ingestion exposure to beryllium, which has heretofore been widely disregarded in the United States, would be of practical importance. Most of the literature of the past 50 years indicates that ingestion and dermal uptake of beryllium are unimportant routes of exposures. The toxicology data generally support this position. However, research is under way to determine whether sensitization to beryllium may occur following exposure via routes other than inhalation, raising the question of whether this sensitization from other routes of exposure makes the lungs more susceptible to inflammation when inhaled doses are encountered. Using published data on other metals, this article describes the likely range of doses that a worker might incur in the workplace due to incidental exposure pathways (i.e., exposures not directly related to inhalation of workplace air), such as hand-to-mouth exposure, dermal contact, and resuspension following deposition of beryllium onto clothing. This analysis indicates that these incidental routes of exposure could contribute to total absorbed doses of beryllium that exceed simple airborne inhalation exposures. Because the doses presented by these alternative exposure pathways could be appreciable compared with the airborne inhaled dose, and could continue even when respirators are worn, these pathways may represent the primary routes of entry of beryllium into the body. We believe that the potential for exposure from these incidental exposure pathways merits additional study.

Use of hydroxyurea in children ages 2 to 5 years with sickle cell disease.

The efficacy and side effects of hydroxyurea in young children with sickle cell disease are unknown. The authors followed-up eight young children (mean age 3.7 years) during therapy with hydroxyurea for an average of 137 weeks. Total and fetal hemoglobin levels rose with hydroxyurea therapy. Hospital admission rates and total hospital days decreased during hydroxyurea therapy. No unexpected toxicity occurred, and growth and development were unaffected. This pilot study suggests that hydroxyurea is safe and effective in young children with sickle cell disease.

Mutagen sensitivity in common cutaneous malignant melanoma and dysplastic naevus syndrome.

Sunlight (ultraviolet radiation) has been identified as the major environmental risk factor for the development of cutaneous malignant melanoma and dysplastic naevi. This is, however, not sufficient to explain all melanoma cases. In recent years much emphasis has been given to genetic susceptibility to melanoma. A biomarker of susceptibility to environmentally related cancer is mutagen sensitivity. This is measured as the number of chromatid breaks in lymphocytes which are exposed to bleomycin in the G2 phase of the cell cycle. It has been described that patients with common melanoma show an increased mutagen sensitivity compared with controls. In the present study mutagen sensitivity was measured in 10 dysplastic naevus syndrome patients and compared with that in 11 patients with common melanoma. We found similar results for common melanoma patients as have been reported earlier: a relatively high mean breaks per cell value (0.93 +/- 0.31). In contrast, melanoma patients with dysplastic naevi showed a significantly (P<0.01) lower mutagen sensitivity value (0.46 +/- 0.34). This phenomenon was even more pronounced when only hereditary dysplastic naevi patients (one or more family members with dysplastic naevi) were considered (n = 5; 0.24 +/- 0.05). These results suggest a difference in the initiation of the carcinogenic process in melanoma with a dysplastic naevus as a precursor and melanoma without dysplastic naevi.

Second moment method for evaluating human health risks from groundwater contaminated by trichloroethylene.

Pollutants in groundwater aquifers may constitute a significant human health risk. A large variation in response may result among human populations experiencing the same level and duration of exposure to pollutants. Variability in response, as a result of exposure to a carcinogenic contaminant such as trichloroethylene (TCE), can be represented by a distribution function of safe doses. Spatial variability in aquifer characteristics and contaminant transport parameters requires the use of stochastic transport models to quantify variability in exposure concentrations. A second moment method is used to evaluate the probability of exceeding safe dose levels for a contaminated aquifer. The name of this method stems from the fact that the formulation is based on the first and second moments of the random variables. With this method, the probability is a function of the variability of contaminant concentration (which incorporates variability in hydrogeologic parameters such as hydraulic conductivity) and the variability in response in the human population. In this manner, the severity of the health risk posed by a contaminated aquifer and the evaluation of appropriate strategies and technologies for aquifer remediation are a function of contaminant concentrations and human health risks. The applicability and limitations of this method are demonstrated with data on groundwater contaminated by TCE at Hill Air Force Base, Utah.