Predicting sediment toxicity using logistic regression: a concentration-addition approach

The question posed in this article is how useful the chemical concentration measurements for predicting the outcome of sediment toxicity tests are. Using matched data on sediment toxicity and sediment chemical concentrations from a number of studies, we investigated several approaches for predicting toxicity based on multiple logistic regression with concentration-addition models. Three models were found to meet criteria for acceptability. The first model uses individual chemicals selected using stepwise selection. The second uses derived variables to reflect combined metal contamination, polycyclic aromatic hydrocarbon (PAH) contamination, and the interaction between metals and PAHs. The third and final model is a separate species model with derived variables. Overall, these models suggest that toxicity may be correctly predicted approximately 77% of the time, although prediction is better for samples identified as nontoxic than for those known to be toxic.     

Profile of urinary arsenic metabolites during pregnancy

Chronic exposure to inorganic arsenic (In-As) from drinking water is associated with different health effects, including skin, lung, bladder, and kidney cancer as well as vascular and possibly reproductive effects. In-As is metabolized through the process of methylation, resulting in the production and excretion of methylated species, mainly monomethylarsenate (MMA) and dimethylarsenate (DMA). Because a large percentage of the dose is excreted in urine, the distribution of urinary In-As, MMA, and DMA is considered a useful indicator of methylation patterns in human populations. Several factors affect these patterns, including sex and exposure level. In this study, we investigated the profile of urinary In-As, MMA, and DMA of pregnant women. Periodic urine samples were collected from early to late pregnancy among 29 pregnant women living in Antofagasta, Chile, who drank tap water containing 40 micro g/L In-As. The total urinary arsenic across four sampling periods increased with increasing weeks of gestation, from an initial mean value of 36.1 to a final value of 54.3 micro g/L. This increase was mainly due to an increase in DMA, resulting in lower percentages of In-As and MMA and a higher percentage of DMA. Our findings indicate that among women exposed to moderate arsenic from drinking water during pregnancy, changes occur in the pattern of urinary arsenic excretion and metabolite distribution. The toxicologic significance of this is not clear, given recent evidence suggesting that intermediate methylated species may be highly toxic. Nevertheless, this study suggests that arsenic metabolism changes throughout the course of pregnancy, which in turn may have toxicologic effects on the developing fetus. Key words: arsenic, arsenic metabolism, arsenic methylation, Chile, pregnancy, urinary arsenic.     

Association of co-occurring psychosocial health problems and increased vulnerability to HIV/AIDS among urban men who have sex with men

OBJECTIVES: We measured the extent to which a set of psychosocial health problems have an additive effect on increasing HIV risk among men who have sex with men (MSM). METHODS: We conducted a cross-sectional household probability telephone sample of MSM in Chicago, Los Angeles, New York, and San Francisco. RESULTS: Psychosocial health problems are highly intercorrelated among urban MSM. Greater numbers of health problems are significantly and positively associated with high-risk sexual behavior and HIV infection. CONCLUSIONS: AIDS prevention among MSM has overwhelmingly focused on sexual risk alone. Other health problems among MSM not only are important in their own right, but also may interact to increase HIV risk. HIV prevention might become more effective by addressing the broader health concerns of MSM while also focusing on sexual risks.     

Open-lung protective ventilation with pressure control ventilation, high-frequency oscillation, and intratracheal pulmonary ventilation results in similar gas exchange, hemodynamics, and lung mechanics

BACKGROUND: Pressure control ventilation (PCV), high-frequency oscillation (HFO), and intratracheal pulmonary ventilation (ITPV) may all be used to provide lung protective ventilation in acute respiratory distress syndrome, but the specific approach that is optimal remains controversial. METHODS: Saline lavage was used to produce acute respiratory distress syndrome in 21 sheep randomly assigned to receive PCV, HFO, or ITPV as follows: positive end-expiratory pressure (PCV and ITPV) and mean airway pressure (HFO) were set in a pressure-decreasing manner after lung recruitment that achieved a ratio of Pao2/Fio2 > 400 mmHg. Respiratory rates were 30 breaths/min, 120 breaths/min, and 8 Hz, respectively, for PCV, ITPV, and HFO. Eucapnia was targeted with peak carinal pressure of no more than 35 cm H2O. Animals were then ventilated for 4 h. RESULTS: There were no differences among groups in gas exchange, lung mechanics, or hemodynamics. Tidal volume (PCV, 8.9 +/- 2.1 ml/kg; ITPV, 2.7 +/- 0.8 ml/kg; HFO, approximately 2.0 ml/kg) and peak carinal pressure (PCV, 30.6 +/- 2.6 cm H2O; ITPV, 22.3 +/- 4.8 cm H2O; HFO, approximately 24.3 cm H2O) were higher in PCV. Pilot histologic data showed greater interstitial hemorrhage and alveolar septal expansion in PCV than in HFO or ITPV. CONCLUSION: These data indicate that HFO, ITPV, and PCV when applied with an open-lung protective ventilatory strategy results in the same gas exchange, lung mechanics, and hemodynamic response, but pilot data indicate that lung injury may be greater with PCV.     

Long-term function after Charnley total hip arthroplasty

The purpose of this study was to report the functional results and mortality rates of a consecutive series of patients younger than 50 years after Charnley total hip arthroplasty. The original group of 69 patients (93 hips) was followed up until death or a minimum of 25 years after surgery. Of the original 93 hips, 29 had been revised at some point. Functional outcomes included the Short Form-36, Western Ontario and McMaster University University Osteoarthritis Index (WOMAC), 6-minute walk distance, Noyes activity scale, and Harris hip scores and included followup in 42 of 43 living patients. The functional outcome of patients was good, with comparable Short Form-36 scores compared with normative values of healthy age-matched subjects. The 6-minute walk distances and WOMAC scores were slightly lower than healthy normatives but were thought to be influenced by medical comorbidities. Although comorbid medical and musculoskeletal conditions significantly hindered most measures of function, revision surgery or radiographic loosening of components had no significant influence on function. The mortality rates of this cohort of patients were similar to normative values at both 10 and 25 years after surgery.     

A randomized,placebo controlled,multicenter study to evaluate the safety and efficacy of rofecoxib in the treatment of chronic nonbacterial prostatitis

PURPOSE: We determine the effects of treatment with rofecoxib and placebo in patients with chronic prostatitis. MATERIALS AND METHODS: Patients diagnosed with chronic nonbacterial prostatitis were randomized to 6 weeks of 25 or 50 mg., rofecoxib or placebo in a double-blind multicenter study with a 1-week run in of placebo. End points included the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) (average pain score item 4 primary end point), and patient global assessment questions of pain, disease activity and response to therapy. RESULTS: A total of 161 patients were randomized in the study. The NIH-CPSI total, domain and pain scores significantly decreased from baseline in all groups and, although the mean scores numerically favored the rofecoxib groups, the difference was not significantly different among groups. There was a trend for the percentage of patients with a 25% (or 6 point) improvement in total score being superior on rofecoxib versus placebo with the difference being significantly different (p <0.05) for the 50 mg. rofecoxib group. Patient global assessment of pain, response to therapy and disease activity also favored rofecoxib over placebo (p <0.05, p = 0.07, p = 0.06, respectively). Of the patients 79% on 50 mg. rofecoxib versus 59% on placebo reported no or mild pain, and 56% of patients on 50 mg. rofecoxib versus 27% on placebo experienced significant improvement in quality of life (p <0.005). Rofecoxib was generally well tolerated. CONCLUSIONS: To our knowledge this study is the first to evaluate rofecoxib versus placebo in patients with prostatitis and the first large multicenter treatment study to use the NIH-CPSI. Subjective assessment with patient global questions may be more sensitive to change than the NIH-CPSI and, therefore, may be a better tool to use in future therapeutic trials. Although 6 weeks of rofecoxib treatment appear to benefit many men diagnosed with chronic prostatitis/chronic pelvic pain syndrome further studies are needed.     

Prostate biopsy culture findings of men with chronic pelvic pain syndrome do not differ from those of healthy controls

PURPOSE: Previous reports have identified bacteria in the prostate of men with chronic pelvic pain syndrome. To examine whether prostatic bacteria are more prevalent among patients with chronic pelvic pain syndrome than among those without pelvic pain, we compared 4-glass urine test and prostate biopsy results. MATERIALS AND METHODS: A total of 120 patients with types IIIa and IIIb chronic pelvic pain syndrome and 60 asymptomatic controls underwent a standard 4-glass urine test, examination of expressed prostatic secretion leukocytes by hemocytometer and transperineal, digitally guided prostate biopsies. Tissue was cultured for aerobes, anaerobes, Trichomonas vaginalis, Chlamydia trachomatis and herpes simplex virus. Skin cultures were performed on a subset of patients and controls. RESULTS: Positive prostate biopsy cultures were obtained from patients and controls. Bacteria were found in 45 of 118 pain patients (38%) and in 21 of 59 controls (36%) (p = 0.74). Older men were more likely to have positive cultures. Men with type IIIa chronic pelvic pain syndrome were more likely than those with type IIIb to have positive prostate biopsy cultures. CONCLUSIONS: Bacteria cultured from transperineal prostatic biopsies do not differ between men with and without chronic pelvic pain syndrome. Prostatic bacteria obtained by biopsy are probably not etiologically related to the symptoms in the majority of men with chronic pelvic pain syndrome.     

Computer-aided detection (CAD) in screening mammography: sensitivity of commercial CAD systems for detecting architectural distortion

OBJECTIVE: Computer-aided detection (CAD) algorithms have successfully revealed breast masses and microcalcifications on screening mammography. The purpose of our study was to evaluate the sensitivity of commercially available CAD systems for revealing architectural distortion, the third most common appearance of breast cancer. MATERIALS AND METHODS: Two commercially available CAD systems were used to evaluate screening mammograms obtained in 43 patients with 45 mammographically detected regions of architectural distortion. For each CAD system, we determined the sensitivity for revealing architectural distortion on at least one image of the two-view mammographic examination (case sensitivity) and for each individual mammogram (image sensitivity). Surgical biopsy results were available for each case of architectural distortion. RESULTS: Architectural distortion was deemed present and actionable by a panel of expert breast imagers in 80 views of the 45 cases. One CAD system detected distortion in 22 of 45 cases of distortion (case sensitivity, 49%) and in 30 of 80 mammograms (image sensitivity, 38%); it displayed 0.7 false-positive marks per image. Another CAD system identified distortion in 15 of 45 cases (case sensitivity, 33%) and 17 of 80 mammograms (image sensitivity, 21%); it displayed 1.27 false-positive marks per image. Sensitivity for malignancy-caused distortion was similar to or lower than sensitivity for all causes of distortion. CONCLUSION: Fewer than one half of the cases of architectural distortion were detected by the two most widely available CAD systems used for interpretations of screening mammograms. Considerable improvement in the sensitivity of CAD systems is needed for detecting this type of lesion. Practicing breast imagers who use CAD systems should remain vigilant for architectural distortion.     

The need for phase-encoding flow compensation in high-resolution intracranial magnetic resonance angiography

PURPOSE: To demonstrate that the time delay between phase and frequency encoding and the presence of pulsatile blood flow in high-resolution time-of-flight (TOF) imaging of the intracranial arteries (especially near the circle of Willis) can distort the appearance of blood vessels and result in a cross-hatch-appearing artifact in surrounding tissue. MATERIALS AND METHODS: Two techniques to reduce the artifact, tri-directional flow compensation (3DFC) and elliptical-centric (EC) phase-encoding order, are investigated in five volunteer studies. RESULTS: 3DFC eliminates the pulsation-related artifacts and the vessel distortion. A residual amplitude variation artifact is observed. EC phase encoding nearly eliminates the pulsatile motion-related artifact, but it does not eliminate vessel distortion. CONCLUSION: The combination of 3DFC and EC phase encoding appears to provide the greatest artifact reduction in the five volunteer studies performed.