BOLD signal physiology: Models and applications.

The BOLD contrast mechanism has a complex relationship with functional brain activity, oxygen metabolism, and neurovascular factors. Accurate interpretation of the BOLD signal for neuroscience and clinical applications necessitates a clear understanding of the sources of BOLD contrast and its relationship to underlying physiology. This review describes the physiological components that contribute to the BOLD signal and the steady-state calibrated BOLD models that enable quantification of functional changes with a separate challenge paradigm. The principles derived from these biophysical models are then used to interpret BOLD measurements in different neurological disorders in the presence of confounding vascular factors related to disease.

Quantitative imaging of bone-cartilage interactions in ACL-injured patients with PET-MRI.

OBJECTIVE: To investigate changes in bone metabolism by positron emission tomography (PET), as well as spatial relationships between bone metabolism and magnetic resonance imaging (MRI) quantitative markers of early cartilage degradation, in anterior cruciate ligament (ACL)-reconstructed knees. DESIGN: Both knees of 15 participants with unilateral reconstructed ACL tears and unaffected contralateral knees were scanned using a simultaneous 3.0T PET-MRI system following injection of 18F-sodium fluoride (18F-NaF). The maximum pixel standardized uptake value (SUVmax) in the subchondral bone and the average T2 relaxation time in cartilage were measured in each knee in eight knee compartments. We tested differences in SUVmax and cartilage T2 relaxation times between the ACL-injured knee and the contralateral control knee as well as spatial relationships between these bone and cartilage changes. RESULTS: Significantly increased subchondral bone 18F-NaF SUVmax and cartilage T2 times were observed in the ACL-reconstructed knees (median [inter-quartile-range (IQR)]: 5.0 [5.8], 36.8 [3.6] ms) compared to the contralateral knees (median [IQR]: 1.9 [1.4], 34.4 [3.8] ms). A spatial relationship between the two markers was also seen. Using the contralateral knee as a control, we observed a significant correlation of r = 0.59 between the difference in subchondral bone SUVmax (between injured and contralateral knees) and the adjacent cartilage T2 (between the two knees) [P < 0.001], with a slope of 0.49 ms/a.u. This correlation and slope were higher in deep layers (r = 0.73, slope = 0.60 ms/a.u.) of cartilage compared to superficial layers (r = 0.40, slope = 0.43 ms/a.u.). CONCLUSIONS: 18F-NaF PET-MR imaging enables detection of increased subchondral bone metabolism in ACL-reconstructed knees and may serve as an important marker of early osteoarthritis (OA) progression. Spatial relationships observed between early OA changes across bone and cartilage support the need to study whole-joint disease mechanisms in OA.

Tobacco control in Vietnam.

OBJECTIVES: To investigate the use of tobacco in Vietnam. STUDY DESIGN: Review study. METHODS: Data were collected through a review of tobacco-related literature in Vietnam. Grey literature and web content from agencies such as the World Health Organization and the US Centers for Disease Control and Prevention were consulted. RESULTS: Tobacco smoking is still common in Vietnam, although numerous policies have been issued and implemented over the last two decades. Based on the most recent data (2010), the prevalence of smoking among adults aged >15 years was 23.8%, with a higher percentage among males (47.4%) than females (1.4%). The prevalence of smoking among students aged 13-15 was 3.8% (2007), with a similar gender pattern. The prevalence of exposure to secondhand smoke is of concern, with 73.1% and 55.9% of adults reporting exposure to secondhand smoke at home and at work or other places, respectively. Of the adult respondents, 55.5% believed that smoking may cause lung cancer, stroke and heart disease. Most students (93.4%) and adults (91.6%) had seen anti-smoking media messages. Of the students, 56.4% had seen pro-cigarette advertisements on billboards, 36.9% had seen pro-cigarette advertisements in newspapers or magazines, and 8.2% had been offered free cigarettes by tobacco company representatives. The price of cigarettes decreased by approximately 5% between 1995 and 2006, whereas gross domestic product per capita increased by more than 150%. On average, smokers smoked 13.5 cigarettes per day, and spent US$86 on cigarettes per year. Despite such high levels of tobacco exposure in Vietnam, the total tax on cigarettes remains at 45% of the retail price. Furthermore, only 29.7% of smokers had been advised to quit by a healthcare provider in the past 12 months. CONCLUSION: Strong enforcement and evidence-based regulations which rounded on MPOWER are needed to help protect current smokers and non-smokers from the devastating effects of tobacco.

Medical education in Vietnam.

BACKGROUND: Vietnam is one of the most populous countries in Southeast Asia, yet it displays an unsettling lack of doctors. AIMS: Medical education is an important factor contributing to this issue, yet little is known about the system currently in place in Vietnam. METHODS: Through an extensive literary search of medical schools' and Ministry of Health's data, we have examined the current medical education system in Vietnam. RESULTS: At present, there are 12 medical universities, and the general curriculum at each university follows a national framework but tends to vary from university to university. Medical training lasts either 4 or 6 years, with competitive graduates attending residency programs following graduation. While examinations are required to graduate, the lack of a national licensing exam makes it difficult to ensure that a nation-wide standard of quality exists, both at the medical universities themselves as well as amongst the doctors graduating from them. CONCLUSIONS: The development and institution of a national exam would introduce a standard of training throughout Vietnam's medical education system. Further, a substantial portion of a doctor's education is in subjects that are loosely related to medicine. When looking forward it will be important to evaluate whether or not these non-medical subjects detract from the quality of medical training.

A longitudinal study of the impact of interviews on medical school admissions in Taiwan.

Medical schools in Taiwan have recently adopted the U.S. medical school admissions model by incorporating interviews into the selection process. The objective of this study was to investigate factors that contribute to successful medical school applications through the national entrance examination and interview admission routes. The sample consisted of survey data from five entry cohorts of medical students admitted to the National Yang-Ming University Faculty of Medicine from 2003 to 2007. Of the 513 students, 62% were admitted through the traditional national entrance examination route and 38% were admitted early after achieving a threshold score on the composite national exam followed by a structured interview. Students admitted through the interview route were more likely to be female, with an odds ratio (OR) of 2.17 (1.20-3.93). Maternal education level was an independent predictor of both early admission through a successful interview and higher medical school grade point average (GPA). Students admitted through the interview route had a 3.20 point higher first-year medical school GPA (p < .001) as determined by regression analyses. Those students who were admitted via interview did not have significantly different personality traits than those admitted through the traditional route. This study calls into question the ability of an admissions interview to select for noncognitive character traits.

Longitudinal study assessing the joint effects of socio-economic status and birth risks on adult emotional and nervous conditions.

BACKGROUND: Previous investigations into the impact of birth complications and social environment have generally followed their subjects only at young ages. AIMS: To assess the long-range impact of socio-economic status (SES) and birth risks on the development of emotional and nervous conditions through adulthood. METHOD: The Johns Hopkins Pathways Study interviewed 1824 subjects born between 1960 and 1965. The median household income of the children at age 7-8 years was used to divide the cohort into high and low income categories. Differences in life time prevalence of emotional and nervous conditions through adulthood between the two income groups were identified. RESULTS: Children in the lower income group were 1.86 times more likely to report an emotional or nervous condition as adults. Boys in the lower income group at age 7-8 years were 3.2 times more likely to do so. The risks of difficult birth for adult mental disturbance were accentuated in the low-income group. CONCLUSIONS: Children who experience birth complications are at increased risk of developing adult mental disturbances; this increase is mitigated by higher SES.

Association of prenatal and perinatal complications with subsequent bipolar disorder and schizophrenia.

This paper presents an overview of the recent literature on the association between prenatal and perinatal complications (PPCs) and schizophrenia, then systematically reviews papers published later than 1965 examining the association of PPCs and bipolar disorder. Three of the four studies comparing bipolar cases with normal controls indicated a positive association of PPCs with the development of bipolar disorder in adult life; the four odds ratios ranged from 1.0 to 12.0. The proportion of PPCs among the bipolar samples without comparison subjects ranged from 3.8% to 50.0%. Issues of study design, measurement and severity of exposure, and outcome are addressed. This review suggests that further investigation of genetic interactions, gender differences, and the specificity of effects in the association between PPCs and mental disorders other than schizophrenia is warranted.