Acute toxicity of zinc to several aquatic species native to the Rocky Mountains.

National water-quality criteria for the protection of aquatic life are based on toxicity tests, often using organisms that are easy to culture in the laboratory. Species native to the Rocky Mountains are poorly represented in data sets used to derive national water-quality criteria. To provide additional data on the toxicity of zinc, several laboratory acute-toxicity tests were conducted with a diverse assortment of fish, benthic invertebrates, and an amphibian native to the Rocky Mountains. Tests with fish were conducted using three subspecies of cutthroat trout (Colorado River cutthroat trout Oncorhynchus clarkii pleuriticus, greenback cutthroat trout O. clarkii stomias, and Rio Grande cutthroat trout O. clarkii virginalis), mountain whitefish (Prosopium williamsoni), mottled sculpin (Cottus bairdi), longnose dace (Rhinichthys cataractae), and flathead chub (Platygobio gracilis). Aquatic invertebrate tests were conducted with mayflies (Baetis tricaudatus, Drunella doddsi, Cinygmula sp. and Ephemerella sp.), a stonefly (Chloroperlidae), and a caddis fly (Lepidostoma sp.). The amphibian test was conducted with tadpoles of the boreal toad (Bufo boreas). Median lethal concentrations (LC(50)s) ranged more than three orders of magnitude from 166 µg/L for Rio Grande cutthroat trout to >67,000 µg/L for several benthic invertebrates. Of the organisms tested, vertebrates were the most sensitive, and benthic invertebrates were the most tolerant.

Discovering the elusive underlying cause of a bilateral effusion combined with ascites.

A 77-year-old Asian man presented to the emergency department with bilateral pleural effusion and ascites accompanied with generalized weakness, dyspnea, tachycardia, and tachypnea. After an extensive workup that ruled out heart failure, pulmonary embolism, pneumonia, and malignancy-including extensive laboratory tests, electrocardiograms, chest x-ray, computed tomographic angiogram, computed tomography scans of the abdomen and pelvis, colonoscopy, thoracentesis, paracentesis, and exploratory laparoscopy-an elusive peritoneal tuberculosis was successfully identified. This case suggests that clinicians should consider extrapulmonary tuberculosis in their practice, given increasing immigration and the variety of populations present in our society. When tuberculosis is suspected, a negative smear for acid-fast bacillus, a lack of granulomas on histopathology, and failure to culture Mycobacterium tuberculosis do not exclude the diagnosis. Exploratory laparoscopy or minilaparotomy has a high level of sensitivity and specificity so should be considered.

Acute toxicity of aqueous copper, cadmium, and zinc to the mayfly Rhithrogena hageni.

Heptageniid mayfly nymphs have been suggested as sensitive indicators of metal contamination in streams based on biomonitoring studies, experimentation in situ, and experimentation in microcosm. Laboratory tests were conducted to evaluate the sensitivity of Rhithrogena hageni, a heptageniid mayfly, to waterborne copper, cadmium, and zinc. Tests were conducted with soft water (hardness = 40-50 mg/L) at about 12 degrees C. Toxicity endpoints were survival and moulting (%/day). Median 96 hr lethal concentrations were 0.137, 10.5, and 50.5 mg/L for copper, cadmium and zinc, respectively. The average daily moulting rate of survivors significantly decreased after exposure to these metals in solution.

Treatment of substance abuse during pregnancy and infant outcome.

The objective of this study is to analyze the effects of residential substance abuse treatment on pregnancy outcome among gravidas in a gender-specific program. All clients (cases) who entered a residential substance abuse program for pregnant and postpartum women were eligible for inclusion in the study (n=95). Only those who were in treatment at the time of delivery were included in the present analysis (n=57). Two comparison groups were used: (1) substance abusers who received no treatment during pregnancy (positive control group) and (2) pregnant women who were not substance abusers (negative control group). Cases were matched to controls on ethnicity (negative and positive controls) and drug of choice (positive controls only). Medical records were reviewed and abstracted for cases and controls. The primary drug of choice was cocaine for 56% of clients in the study, heroin 15.8%, and alcohol 10.8%. Average length of time in treatment before delivery was 11.7 weeks. The frequency of pregnancy complications allowing treatment and position controls was significantly higher than the negative control group (p<0.0001). The frequency of perinatal infant complications was increased among treatment group infants (p<0.0001). Two infants in the treatment group were positive for a substance of abuse at birth. In the treatment versus positive control group, mean birth weight (BW) was 3227 versus 2800 g (p<0.01), estimated gestational age (EGA) was 38.9 versus 39 weeks, average head circumference (FOC) was 33.8 versus 32.5 cm (p<0.05), and mean birth length (BLT) was 48.7 cm versus 46.9 (p<0.05). No significant differences were found between treatment and negative control groups. Maternal syphilis was increased in frequency in the positive control group compared with the negative control group (p<0.07). Thirty-percent of mothers had sexually transmitted diseases (STDs) for which infants were at risk and treated prophylactically; no infant in the treatment group contracted a vertically transmitted STD. For every 10 weeks in treatment, BW was increased 340 g, EGA 1 week, FOC 0.8 cm, and BLT 1.8 cm. Thus, substance abuse treatment for pregnant women in the program increased fetal growth, which significantly decreased the risk for poor neonatal outcomes. Importantly, maternal and infant perinatal complications in the treatment group were increased in frequency compared with the two control groups. This may possibly have occurred because healthcare providers were not blinded to maternal treatment status.