Stress Modulates the Balance between Hippocampal and Motor Networks during Motor Memory Processing.

The functional interaction between hippocampo- and striato-cortical regions during motor sequence learning is essential to trigger optimal memory consolidation. Based on previous evidence from other memory domains that stress alters the balance between these systems, we investigated whether exposure to stress prior to motor learning modulates motor memory processes. Seventy-two healthy young individuals were exposed to a stressful or nonstressful control intervention prior to training on a motor sequence learning task in a magnetic resonance imaging (MRI) scanner. Consolidation was assessed with an MRI retest after a sleep episode. Behavioral results indicate that stress prior to learning did not influence motor performance. At the neural level, stress induced both a larger recruitment of sensorimotor regions and a greater disengagement of hippocampo-cortical networks during training. Brain-behavior regression analyses showed that while this stress-induced shift from (hippocampo-)fronto-parietal to motor networks was beneficial for initial performance, it was detrimental for consolidation. Our results provide the first experimental evidence that stress modulates the neural networks recruited during motor memory processing and therefore effectively unify concepts and mechanisms from diverse memory fields. Critically, our findings suggest that intersubject variability in brain responses to stress determines the impact of stress on motor learning and subsequent consolidation.

Genotoxic effects of ochratoxin A in human-derived hepatoma (HepG2) cells.

Ochratoxin A (OTA) is a widespread mycotoxin that occurs in many commodities from grains to coffee beans all over the world. Evidence is accumulating that OTA may cause cancer in humans. The compound was tested in micronucleus (MN) and single-cell gel electrophoresis (SCGE) assays in human-derived hepatoma (HepG2) cells and caused pronounced dose-dependent effects at exposure concentrations of 5 microg/ml and greater. On the contrary, no induction of His(+) revertants was found in Salmonella microsome assays with strains TA98 and TA100 with HepG2-derived enzyme (S9) mix in liquid incubation assays under identical exposure concentrations. Taken together, our results indicate that OTA is clastogenic in the human-derived cells. These findings support the assumption that this mycotoxin may cause genotoxic effects in hepatic tissue of humans.

Efficacy of ursodeoxycholic acid in the treatment of primary sclerosing cholangitis in children.

BACKGROUND: Ursodeoxycholic acid (UDCA) has been shown to be beneficial in reducing disease activity in adult patients with primary sclerosing cholangitis (PSC). However, there has been little published regarding PSC in children and no studies investigating the efficacy of UDCA as a treatment for PSC. METHODS: This retrospective study included 10 children who were found to have the diagnosis of PSC during the past 15 years at the Texas Children's Hospital and Herman Hospital, both in Houston, Texas. The male:female ratio was 8:2, the median age of onset was 12 years (range, 1-17 years), and eight patients had coexistent inflammatory bowel disease (IBD; six ulcerative colitis, one Crohn's disease, one unspecified). At the time of diagnosis, five patients were asymptomatic, all of whom had IBD with elevated liver enzymes and three of whom had hepatomegaly. Nine patients were treated with UDCA. The one patient who did not receive UDCA was lost to follow-up soon after diagnosis. The mean dose of UDCA was 17 mg/kg with the doses ranging from 9 to 37 mg/kg. RESULTS: There were no side effects from the medication recorded for any of the patients. These patients showed a significant reduction in alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase at 1, 3, 6, 15, and 20 months after treatment. CONCLUSIONS: This study demonstrates that children with PSC treated with UDCA have significant improvements in liver biochemical indices. However, the long-term effect of UDCA on clinical outcome is unknown.

Exposure to formaldehyde and phenol during an anatomy dissecting course: sensitizing potency of formaldehyde in medical students.

BACKGROUND: The sensitizing potency of formaldehyde and phenol during anatomy dissecting was investigated. The objective was to determine whether exposure induces specific IgE or IgG against formaldehyde-albumin or phenol-albumin. METHODS: In 27 medical students, specific IgE against formaldehyde-albumin by RAST plus ELISA and specific IgE against phenol-albumin by ELISA were assessed. In addition, specific IgG against formaldehyde-albumin was assessed in 23 students. Symptoms before and during dissecting were assessed, and indoor formaldehyde and phenol were measured. RESULTS: Mean indoor formaldehyde was 0.265 +/- 0.07 mg/m3, and mean indoor phenol was 4.65 +/- 2.96 mg/m3. Specific IgE/IgG against formaldehyde-albumin was not found at the beginning. Four students developed specific IgE against formaldehyde-albumin (RAST classes of > or =2.0), and all four also had specific IgE in the ELISA, but IgG against formaldehyde-albumin was not found. Specific IgE against phenol-albumin was not seen. Itch and paresthesia of the hands (P<0.00001), dizziness (P<0.008), burning eyes (P<0.01), headache, sneezing, epistaxis, gingival bleeding, oral or pharyngeal itch, and shortness of breath were experienced. CONCLUSIONS: Formaldehyde exposure during dissecting may induce specific IgE, but not IgG, against formaldehyde-albumin. Sensitization did not correlate with symptoms.

Formaldehyde and phenol exposure during an anatomy dissection course: a possible source of IgE-mediated sensitization?

The sensitizing potency of formaldehyde and phenol exposure during 4 weeks of an anatomy dissection course was assessed in 45 medical students. Specific IgE against formaldehyde by RAST and by ELISA and specific IgE against phenol by ELISA were assessed before and after the course. At the start of the course, symptoms, type I allergy, respiratory diseases, and smoking habits were noted. At the end of the course, only symptoms experienced during the dissection lessons were assessed. Indoor formaldehyde levels were measured continuously. The mean indoor formaldehyde level was 0.124 +/- 0.05 ppm, with a minimum of 0.059 ppm and a maximum of 0.219 ppm. Specific IgE against formaldehyde or phenol was found in none of the subjects at the beginning of the course, and no student showed specific IgE against formaldehyde or phenol after the course. Assessment of primarily irritant symptoms during the lesson revealed itch and paraesthesia of hands in 33/45 students (P < 0.00005), headache in 15/45 students, burning eyes in 13/45 students (P < 0.02), dizziness in 8/45 students (P < 0.008), sneezing in 4/45 students, epistaxis in 2/45 students, and shortness of breath in 1/45 students. According to our data, 1-month exposure to formaldehyde and phenol during an anatomy dissection course does not induce specific IgE against formaldehyde or phenol.

A systematic approach to health surveillance in the workplace.

This paper reviews the range of health surveillance activities which can be utilized in the workplace by occupational health professionals for assessing fitness for work and contributing to the prevention of occupational illness and promotion of good health. The systematic approach described categorizes health surveillance procedures into occupational or non-occupational, risk-based or unfocused, and as primary, secondary or tertiary preventive measures. All categories of health surveillance are currently being practised to some extent, but the type of surveillance may not match the needs of the workplace in some situation. In order to aid health professionals in deciding which procedures should be implemented, recommendations based on an assessment of health risks are made. The key proposal is to establish a minimum level of periodic health surveillance for all workers based on a targeted lifestyle health risk assessment and a structured health questionnaire. Additional procedures can then be added sequentially as appropriate to manage any health risks in the workplace. The role of the unfocused periodic general medical examination is discussed in the context of the systematic approach and allows occupational professionals to critically appraise its usefulness.

A simple approach to screening for microalbuminuria in a type 1 (insulin-dependent) diabetic population.

The reproducibility of albumin concentration in first-morning samples of urine was assessed in 334 insulin-dependent diabetic patients aged 18-60 years. The albumin excretion rate was determined immunoturbidimetrically in three sterile, Albustix-negative, first-morning urine samples submitted over a week. An abnormally high mean value, greater than or equal to 2.5 mg albumin per mmol creatinine (Ua/Uc), was found in 33 patients (9.9%). These patients were older (mean 42 vs 34 years, P less than 0.01), had longer disease duration (18 vs 14 years, P less than 0.01) and higher HbA1c values (6.8 vs 6.3%, P less than 0.05) than those without microalbuminuria. Although triplicate samples were collected within 7 days, Ua/Uc showed considerable intraindividual variation, with a mean coefficient of variation of 49%. Despite this it was found that Ua/Uc values greater than 1 mg/mmol on the first specimen had a sensitivity of 97% and a specificity of 82% for detecting those with a three-sample mean value greater than 2.5 mg/mmol. Thus virtually all those with microalbuminuria (32/33) had a single first-morning result greater than 1 mg/mmol, and in those with a lower ratio microalbuminuria was excluded with more than 99% certainty.

The application of a short anxiety and depression questionnaire to oil industry staff.

A short anxiety and depression questionnaire developed by Goldberg et al. was applied to 796 employees of an oil company operating offshore in the North Sea. Anxiety and depression scores were compared in offshore staff and their onshore counterparts at different levels of seniority. These scores were taken to be indicators of stress levels. No statistically significant differences in anxiety or depression scores were identified between groups working onshore or offshore.

Ultrastructural studies of influenza C. II. von Magnus phenomenon.

Influenza C was propagated by serial undiluted passage; conditions known to produce non-infectious (von Magnus) particles with influenza A and B. Following each passage infectious material was assayed for infectivity and haemagglutinating activity and the values related by calculating the log difference between infectivity and haemagglutinating titre (I:A ratio). Infectious material from each pass was examined for ultrastruct aberrations by negative strain electron microscopy. Influenza C exhibited a significantly smaller decrease in I:A ratio than exhibiyed by similarly propagated influenza A and B. Ultrastructural examination of the serially passed influenza C revealed no production of morphologically aberrant forms, whereas serially passed influenza B produced a strikingly altered morphology.