Toxicity of methyl tert-butyl ether to plants (Avena sativa,Zea mays,Triticum aestivum,and Lactuca sativa)

Influence of methyl tert-butyl ether (MTBE) on the germination of seeds and growth of seedling plants were studied in laboratory experiments. Test plants were wild oats (Avena sativa), sweet corn (Zea mays), wheat (Triticum aestivum), and lettuce (Lactuca sativa). Seed germination, shoot growth, and root growth of plants exposed to different concentrations of MTBE in a moist soil were examined. Seed germination and seedling growth in MTBE-contaminated soil were markedly reduced in all test plants. The median lethal concentration values for seed germination tests and the median effective concentration values for shoot or root growth were calculated. The values for lettuce, wild oats, wheat, and sweet corn were in the range of 18 to 91, 362 to 459, 432 to 751, and 672 to 964 mg MTBE/kg soil as dry weight, respectively. Lettuce was most sensitive to MTBE, followed (in order of decreasing sensitivity) by wild oats, wheat, and sweet corn. Because MTBE can be readily absorbed by plants due to its high solubility in water, plant growth was a more sensitive endpoint than seed germination. Shoot length was more reduced in MTBE-contaminated soil than was the root length, which indicated that MTBE might be transported within the plant from the roots to the shoots.     

Temporal changes in collagen composition and metabolism during rodent palatogenesis

Cleft lip and palate is a common craniofacial malformation in man. The aetiology is multifactorial and not known. Since collagen is a major structural component of the developing palate, we studied its composition and metabolism during palate shelf formation and elevation in the rat. Palatal shelves were harvested at embryonic days (E) 15, 16 and 17 as well as post-partum. Palatal collagen increased threefold from E15 to E17 and tenfold from E17 to 5-day-old pups. Palatal calcification was seen in the main, post-partum. Collagen cross-linking, which may be important in shelf elevation and union, varied. The concentration of hydroxylysyl-pyridinolone cross-links was greatest prior to shelf elevation, declining thereafter. Similarly, the highest concentration of dihydroxylysinononorleucine was seen at E16 and this supports the concept of a compliant mesenchymal shelf responding to an intrinsic elevating force. We then determined if enzymes responsible for matrix degradation, matrix metalloproteinases (MMP) and the tissue inhibitors of metalloproteinases (TIMPs) altered over the same time periods. MMP-2, and TIMP-1 and TIMP-2 were identified by gelatin zymography and reverse zymography, respectively. MMP-3 activity was determined with a fluorogenic substrate assay. TIMP-1, TIMP-2 and MMP-3 levels remained constant from E15 to E17. The MMP-2 levels showed a significant elevation from E15 to E16 and E16 to E17. This suggests the regulation of extracellular matrix is likely to be of importance in palate morphogenesis.     

Creatinine related reference ranges for urinary homovanillic acid and vanillylmandelic acid at 6 months of age

The relationship between homovanillic acid (HVA), vanillylmandelic acid (VMA), and creatinine in the urine of 6 month old babies has been studied and reference ranges in the form of centiles constructed for HVA and VMA against creatinine. Over 10,000 urine samples were collected from babies in four health districts in the north of England. HVA and VMA concentration, either independently or when divided by creatinine concentration, were dependent upon the absolute concentration of creatinine in the sample. After adjustment for creatinine significant differences in the mean concentration of HVA were found between sexes. No such differences were found for VMA. HVA and VMA were also found to be age dependent. Centiles were constructed using a procedure which makes no distributional assumptions about the data. The net effect of utilising these centiles was to increase the predictive value of a positive screening test from 20% to 40% without any increase in the false negative rate.     

Initiating abstinence in cocaine abusing dually diagnosed homeless persons

This study measured effectiveness of behavioral day treatment plus abstinence contingent housing and work therapy (DT+) versus behavioral day treatment alone (DT). A randomized controlled trial assessed participants at baseline, 2 and 6 months. Participants (N=110) met criteria for cocaine abuse or dependence, non-psychotic mental disorders, and homelessness. DT+ achieved greater abstinence at 2 and 6 months and more days housed at 6 months than DT. Effectiveness of DT+ was demonstrated, with greatest impacts on abstinence outcomes. Results replicated earlier work demonstrating effectiveness of behavioral day treatment and contingency management as an effective combination for cocaine abusing homeless persons.     

Role of visual acuity, stereoacuity, and ocular dominance in monovision patient success.

Monovision (MV) contact lens correction of presbyopia induces substantial reductions in stereoacuity and small reductions in binocular visual acuity (VA). This study examined those effects in a group of successful and a group of unsuccessful MV patients. Compared to performance with a full binocular correction, the unsuccessful group demonstrated significant losses in both functions. These reductions were smaller in the successful group and of marginal statistical significance only for stereoacuity. Laterality of sighting dominance and laterality of distance/near correction had minimal effect on the results.     

Perinatal market penetration rate. A tool to evaluate regional perinatal programs

Very small babies born in tertiary centers fare better than outborn babies referred for tertiary care after birth. Viewing the 1001-1500 gm regional cohort of fetuses as a potential "market" for center delivery, and measuring a center's penetration into this market, quantitates how well a center draws to itself these small, high-risk fetuses for delivery. An Illinois center's annual penetration rate into its regional market for the years 1973-1983 is presented and significant increases are found. The penetration rates of nine Illinois perinatal centers are calculated and wide discrepancies are found. Defining a high-risk regional cohort as a market stresses a perinatal center's obligation to its region. The penetration rate into a defined market measures how well a center fulfills this obligation.     

Fibrinolytic response to moderate exercise in young male diabetics and non-diabetics

The euglobulin lysis time was measured in 25 young male insulin-dependent diabetics and 25 age- and sex-matched healthy controls before and after a standardized moderate treadmill exercise procedure. There was a statistically significant mean shorter resting euglobulin lysis time in the diabetic group but their ability to respond to the exercise procedure was significantly impaired. It is suggested that this impaired fibrinolytic reactivity may be related to the diminished vaso-active reactivity previously reported in young diabetics.     

Glucose-galactose malabsorption in an adult: Perfusion studies of sugar,electrolyte, and water transport

Glucose-galactose malabsorption, a rare congenital impairment of monosaccharide absorption which causes severe diarrhea, is described in an otherwise normal 21-year-old man. The diagnosis was made by sugar tolerance tests and confirmed by jejunal perfusion studies. Treatment by restriction of dietary sugars and by caloric supplements with fructose controlled the diarrhea effectively and resulted in weight gain. Perfusion studies of the jejunum documented decreased absorption of glucose and galactose and normal absorption of fructose. The basal potential difference of the jejunal mucosa was normal, but potential difference was unresponsive to the addition of intraluminal glucose. The jejunal mucosa secreted electrolytes and fluid, suggesting that a coupled glucose-sodium-water absorptive process may be defective in this condition.This investigation was supported in part by Research Grant AM-6908 from the National Institutes of Health, Public Health Service.