Effects of short and prolonged transcutaneous vagus nerve stimulation on heart rate variability in healthy subjects.

The vagus nerve is strategically located in the body, and has multiple homeostatic and health-promoting effects. Low vagal activity predicts onset and progression of diseases. These are the reasons to activate this nerve. This study examined the effects of transcutaneous vagus nerve stimulation (t-VNS) on a main index of vagal activity, namely heart rate variability (HRV). In Study 1, we compared short (10min) left versus right ear t-VNS versus sham (no stimulation) in a within-subjects experimental design. Results revealed significant increases in only one HRV parameter (standard deviation of the RR intervals (SDNN)) following right-ear t-VNS. Study 2 examined the prolonged effects of t-VNS (1h) in the right ear. Compared to baseline, right-t-VNS significantly increased the LF and LF/HF components of HRV, and SDNN in women, but not in men. These results show limited effects of t-VNS on HRV, and are discussed in light of neuroanatomical and statistical considerations and future directions are proposed.

Anxious women do not show the expected decrease in cardiovascular stress responsiveness as pregnancy advances.

Altered stress responsiveness is a risk factor for mental and physical illness. In non-pregnant populations, it is well-known that anxiety can alter the physiological regulation of stress reactivity. Characterization of corresponding risks for pregnant women and their offspring requires greater understanding of how stress reactivity and recovery are influenced by pregnancy and women's anxiety feelings. In the current study, women were presented repeatedly with mental arithmetic stress tasks in the first and third pregnancy trimester and reported their trait anxiety using the state trait anxiety inventory. Cardiovascular stress reactivity in late pregnancy was lower than reactivity in the first pregnancy trimester (heart rate (HR): t(197)=4.98, p<.001; high frequency heart rate variability (HF HRV): t(196)=-2.09, p=.04). Less attenuation of stress reactivity occurred in more anxious women (HR: b=0.15, SE=0.06, p=.008; HF HRV: b=-10.97, SE=4.79, p=.02). The study design did not allow the influence of habituation to repeated stress task exposure to be assessed separately from the influence of pregnancy progression. Although this is a limitation, the clear differences between anxious and non-anxious pregnant women are important, regardless of the extent to which differing habituation between the groups is responsible. Less dampened stress reactivity through pregnancy may pose long-term risks for anxious women and their offspring. Follow-up studies are required to determine these risks.

The rate of treatment of chronic hepatitis C in patients co-infected with HIV in an urban medical centre.

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection is common. HIV co-infection results in a higher rate of histologic progression and shorter interval to HCV-related cirrhosis. Successful treatment of HCV with interferon-based therapy reduces the morbidity and mortality of patients. Significant factors may limit the availability of treatment in co-infected patients. The rate of treatment of HCV and limiting factors to treatment in a co-infected population in an urban setting were determined. A retrospective review of co-infected patients was conducted at our liver and gastrointestinal (GI) clinics for treatment of HCV from July 2001 to June 2002. Treatment of HCV and reasons for nontreatment were recorded. A total of 104 HCV/HIV co-infected patients were identified. Seventy-two per cent were males. Mean age was 47.2 years (32-72). Seventy-four of the 82 (90%) with identifiable risk factors for HCV infection had a history of intravenous drug use (IVDU). Twenty per cent (21/104) of the total underwent a liver biopsy. Sixty-seven per cent who had a liver biopsy were treated. Overall, sixteen patients were treated. Eighty-eight (85%) patients were not treated for the following reasons: 13 refused treatment, and 75 were ineligible. Of the ineligible patients, 40% were noncompliant with visits, 15% were active substance abusers, 13% had decompensated cirrhosis, 8% had significant active psychiatric conditions and 24% had significant co-morbid disease. A majority of patients co-infected with HCV/HIV had a IVDU history. Most co-infected patients were not eligible for HCV treatment. A majority of noncandidates had potentially modifiable psychosocial factors leading to nontreatment.

Causes of low vision and blindness in rural Indonesia.

AIM: To determine the prevalence rates and major contributing causes of low vision and blindness in adults in a rural setting in Indonesia METHODS: A population based prevalence survey of adults 21 years or older (n=989) was conducted in five rural villages and one provincial town in Sumatra, Indonesia. One stage household cluster sampling procedure was employed where 100 households were randomly selected from each village or town. Bilateral low vision was defined as habitual VA (measured using tumbling "E" logMAR charts) in the better eye worse than 6/18 and 3/60 or better, based on the WHO criteria. Bilateral blindness was defined as habitual VA worse than 3/60 in the better eye. The anterior segment and lens of subjects with low vision or blindness (both unilateral and bilateral) (n=66) were examined using a portable slit lamp and fundus examination was performed using indirect ophthalmoscopy. RESULTS: The overall age adjusted (adjusted to the 1990 Indonesia census population) prevalence rate of bilateral low vision was 5.8% (95% confidence interval (CI) 4.2 to 7.4) and bilateral blindness was 2.2% (95% CI 1.1 to 3.2). The rates of low vision and blindness increased with age. The major contributing causes for bilateral low vision were cataract (61.3%), uncorrected refractive error (12.9%), and amblyopia (12.9%), and the major cause of bilateral blindness was cataract (62.5%). The major causes of unilateral low vision were cataract (48.0%) and uncorrected refractive error (12.0%), and major causes of unilateral blindness were amblyopia (50.0%) and trauma (50.0%). CONCLUSIONS: The rates of habitual low vision and blindness in provincial Sumatra, Indonesia, are similar to other developing rural countries in Asia. Blindness is largely preventable, as the major contributing causes (cataract and uncorrected refractive error) are amenable to treatment.

Pterygium in Indonesia: prevalence, severity and risk factors.

AIM: To determine prevalence rates, severity, and risk factors for pterygium in adults in provincial Indonesia and to validate a clinical grading scheme in a population based setting. METHODS: A population based prevalence survey of 1210 adults aged 21 years and above was conducted in five rural villages and one provincial town in Riau province, Sumatra, Indonesia, an area near to the equator. A one stage household cluster sampling procedure was employed: 100 households were randomly selected from each village or town. Pterygia were graded for severity (T1 to T3, by visibility of episcleral vessels) and the basal and apical extent measured by an ophthalmologist (GG) with a hand held slit lamp. Refraction was measured by hand held autorefractor (Retinomax). Face to face household interviews assessed outdoor activity, occupation, and smoking. The participation rate was 96.7%. RESULTS: The mean age was 36.6 years (SD 13.1), 612 were male. The age adjusted prevalence rate of any pterygium was 10.0% (95% confidence intervals (CI) 8.2 to 11.7) and of bilateral pterygia was 4.1% (95% CI 2.9 to 5.3). There was a significant dose-response relation with age (2.9% (95% CI 0.4 to 5.8) for 21-29 years versus 17.3% (95% CI 10.4 to 24.2) 50 years and above; p for trend <0.001) and occupations with more time outdoors (p for trend = 0.02). This was true for both sexes, all grades of lesion (T1 to T3), and bilateral disease. A multivariate logistic regression model showed pterygium was independently related to increasing age and outdoor activity 10 years earlier. The mean basal diameter = 3.3 mm (SD 1.51, range 0.1-9.5) and extent from limbus = 1.4 mm (SD 1.18, range 0.1-8.0). Higher grade pterygia were larger for basal and apical extent (p for trend <0.001). The presence of pterygium was associated with astigmatism (defined as cylinder at least -0.5 dioptres (D); p <0.001). This association increased with increasing grade of lesion (p for trend <0.001). Median cylinder for those with pterygium (-0.50 D) was greater than for those without (-0.25D), (p <0.001), and increased with higher grade of lesion (p for trend <0.001). For eyes with pterygia, magnitude of astigmatism was associated with greatest extent from the limbus, (p = 0.03), but not basal width (p = 0.99). CONCLUSIONS: There is a high prevalence rate of pterygia in provincial Sumatra. The independent increase with age and past outdoor activity (a surrogate for sun exposure) is consistent with previous findings. Clinical grading of pterygium morphology by the opacity of the lesion was a useful additional marker of severity.

Prevalence and risk factors associated with dry eye symptoms: a population based study in Indonesia.

AIM: To determine the prevalence and identify associated risk factors for dry eye syndrome in a population in Sumatra, Indonesia. METHODS: A one stage cluster sampling procedure was conducted to randomly select 100 households in each of the five rural villages and one provincial town of the Riau province, Indonesia, from April to June 2001. Interviewers collected demographic, lifestyle, and medical data from 1058 participants aged 21 years or over. Symptoms of dry eye were assessed using a six item validated questionnaire. Presence of one or more of the six dry eye symptoms often or all the time was analysed. Presence of pterygium was documented. RESULTS: Prevalence of one or more of the six dry eye symptoms often or all the time adjusted for age was 27.5% (95% confidence interval (CI) 24.8 to 30.2). After adjusting for all significant variables, independent risk factors for dry eye were pterygium (p<0.001, multivariate odds ratio (OR) 1.8; 95% CI 1.4 to 2.5) and a history of current cigarette smoking (p=0.05, multivariate OR 1.5; 95% CI 1.0 to 2.2). CONCLUSIONS: This population based study provides prevalence rates of dry eye symptoms in a tropical developing nation. From our findings, pterygium is a possible independent risk factor for dry eye symptoms.