Leptin prevents the metabolic effects of adiponectin in L6 myotubes

AIMS/HYPOTHESIS

Adiponectin and leptin are negatively and positively correlated with human obesity respectively, and have both been shown to regulate energy metabolism in skeletal muscle. However, little is known about their signalling and functional crosstalk. Here we investigated the effects of leptin on metabolic actions of (1) globular adiponectin (gAd) and (2) full-length adiponectin (fAd) in L6 cells.

METHODS

Glucose uptake was measured upon gAd and fAd treatment after incubation with different doses (0.3, 0.6, 3, 6, 60 nmol/l) of leptin for 6, 12 and 24 h. We also measured adiponectin receptor (ADIPOR) expression and stimulation of downstream signalling by gAd and fAd using co-immunoprecipitation and western blotting following leptin pretreatment, as well as analysis of fatty acid uptake and oxidation using radiolabelled tracers.

RESULTS

Leptin attenuated the stimulation of glucose uptake by gAd and fAd in a dose- and time-dependent manner, a finding correlated with decreased levels of ADIPOR1 and ADIPOR2. gAd and fAd increased palmitate uptake via activation of AMP protein kinase (T172), enhanced expression of the fatty acid transporter CD36, phosphorylated acetyl-CoA carboxylase (S79) and enhanced palmitate oxidation, all of which were attenuated by leptin pretreatment. Adiponectin can also enhance insulin sensitivity via direct signalling crosstalk; here we show that enhanced insulin-stimulated IRS-1 (Y612) and Akt (T308) phosphorylation in response to fAd was attenuated by leptin. APPL1 was recently identified as a critical mediator of adiponectin action in skeletal muscle. We demonstrated that leptin attenuated binding of APPL1 to LKB1, a downstream target leading to AMPK phosphorylation.

CONCLUSIONS/INTERPRETATION

The direct metabolic and insulin-sensitising effects of adiponectin were attenuated in the presence of leptin.

'I felt I have grown up as an adult': caregiving experience of children affected by HIV/AIDS in China

BACKGROUND

The growing global epidemic of HIV/AIDS has a significant impact on the lives of both people living with HIV/AIDS and their family members including children. Children of parents with HIV/AIDS may experience an increased responsibility of caregiving in family. However, limited data are available regarding the caregiving experience and its impact on psychosocial well-being among these children. This study was designed to address these issues by using qualitative data collected from children affected by HIV/AIDS in China.

METHODS

The qualitative data were collected in 2006 in rural central China, where many residents were infected with HIV/AIDS through unhygienic blood collection procedures. In-depth individual interviews were conducted by trained interviewers with 47 children between 8 and 17 years of age who had lost one or both parents to AIDS.

RESULTS

Findings of this study suggest that many children affected by AIDS had experienced increased responsibilities in housework and caregiving for family members. Such caregiving included caring for self and younger siblings, caring for parents with illness and caring for elderly grandparents. Positive impacts from children's participation in family caregiving included personal growth and emotional maturity. Negative consequences included physical fatigue, psychological fear and anxiety and suboptimal schooling (dropping out from school, repeated absence from school and unable to concentrate in class).

CONCLUSION

While the increased caregiving responsibilities among children reflected some cultural beliefs and had some positive effect on personal growth, the caregiving experience generally negatively effected the children's physical and mental health and schooling. The findings in the current study suggest that community-based caregiving support is necessary in areas with high prevalence of HIV and limited resources, especially for the families lacking adult caregivers. In addition, social and psychological support should be made available for children participating in family caregiving.

Sibling separation and psychological problems of double AIDS orphans in rural China - a comparison analysis

OBJECTIVE

We investigated the psychological impact of sibling separation among children who lost both of their parents to AIDS and were placed in group care or kinship care settings in rural China.

METHODS

Comparative analysis of cross-sectional survey data among 155 children among whom 96 experienced sibling separation. Trauma symptoms (Anxiety, Depression, Anger, Post-traumatic stress, Dissociation, Sexual concerns) were compared between the AIDS orphans who experienced sibling separation and those who did not using analysis of variance and multivariate analysis of covariance.

RESULTS

Among the participants (47.7% girls) with an average age of 12.4 years, univariate and multivariate analyses showed that separation from siblings was associated with significantly higher scores in anxiety, depression, anger and dissociation before or after controlling for gender, age, care arrangement, number of household replacement, trusting relationship with the current caregivers and perceived quality of current living condition. Sibling separation among orphans was not associated with level of post-traumatic stress and sexual concerns.

CONCLUSION

AIDS orphans separated from their siblings suffered from increased psychological distress compared with those who remained with their siblings. The data in the current study suggest that care arrangement for AIDS orphan should include accommodating the siblings together or providing them with opportunities for frequent contact and/or communication with each other. Appropriate psychological counselling should be given to those orphans experiencing sibling separation.

Personal Social Capital Scale: an instrument for health and behavioral research

The concept of social capital has drawn much attention in social and behavioral epidemiology and health education research. The purpose of this study is to develop the 'Personal Social Capital Scale' for quantitative survey studies of social factors that are related to health and behavior. The instrument contained 10 composite items based on 42 items for assessing personally owned social capital, including bonding and bridging capitals. The instrument was assessed using cross-sectional survey data collected among 128 participants (64 women) with a participation rate of 95%. Results from correlation and confirmatory factor analysis indicated adequate reliability and internal consistency. The mean score of the scale was 25.9 (SD = 5.2) for total social capital, 15.2 (SD = 3.0) for bonding social capital and 10.8 (SD = 3.4) for bridging social capital. The scale scores significantly predicted a number of theoretically related factors, including people skills, being sociable, social capital investment, informational support, instrumental support, emotional support and collective efficacy. This instrument provides a new tool for cross-cultural research to assess personally owned social capital.

Optical coherence tomographic characteristics and surgical outcome of eyes with myopic foveoschisis

AIM

To describe the optical coherence topographic (OCT) characteristics and outcome of vitrectomy with triamcinolone acetonide (TA)-assisted epiretinal tissue removal and gas tamponade in eyes with myopic foveoschisis (MF).

METHODS

We examined 101 myopic eyes, and the OCT characteristics of 18 eyes (18%) with an MF were studied. Six eyes underwent vitrectomy with TA-assisted epiretinal tissue removal and gas tamponade. The postoperative outcome measures were best-corrected visual acuity (BCVA), resolution of the MF as determined by OCT, and complications.

RESULTS

OCT scans showed an isolated MF in three (17%) eyes, and the MF were associated with two or more macular anomalies in 15 (83%) eyes. A foveal detachment was found in 13 (72%), lamellar macular hole in 4 (22%), and a tractional epimacular membrane in 11 (61%) of the 18 eyes. Six eyes underwent surgery, in which the epiretinal tissue was made visible by intravitreal TA and completely removed. The median BCVA significantly improved from 20/400 preoperatively (range, 20/1000-20/160) to 20/160 postoperatively (range, 20/200-20/40; P=0.03, Wilcoxon signed-rank test). The mean VA improved by 5.6 lines. OCT showed a complete reattachment of the fovea in four (67%) eyes and a small subfoveal or parafoveal detachment in two (33%) eyes.

CONCLUSIONS

MF is commonly observed in highly myopic eyes and most are associated with one or more macular anomalies. Vitrectomy with TA-assisted complete removal of all tractional premacular structures followed by gas tamponade resulted in good visual and anatomical outcomes for treating MF.

Care arrangements, grief and psychological problems among children orphaned by AIDS in China

The China Ministry of Health has estimated that there are at least 100,000 AIDS orphans in China. The UNICEF China Office estimates that between 150,000 and 250,000 additional children will be orphaned by AIDS over the next five years. However, limited data are available regarding the sociodemographic characteristics, care arrangements, barriers to appropriate grief resolution and psychological problems among AIDS orphans in China. In this article, we review secondary data and reports from scientific literature, government, non-governmental organisations and public media regarding children orphaned by AIDS in China to address their living situation, bereavement process and psychological problems. Our review suggests that AIDS orphans in China are living in a stressful environment, with many orphans struggling with psychological problems and unmet basic needs such as food, shelter, education and medical care. Based on our review, we suggest that future studies should address the psychosocial needs of AIDS orphans in China and develop health promotion programmes to mitigate the negative impact of parental death on the physical and psychosocial well-being of these orphans.

Pathogenic characteristics of the Korean 2002 isolate of foot-and-mouth disease virus serotype O in pigs and cattle

Experimental infection of susceptible cattle and pigs showed that the O/SKR/AS/2002 pig strain of foot-and-mouth disease virus (FMDV) causes an infection that is highly virulent and contagious in pigs but very limited in cattle. Pigs directly inoculated with, or exposed to swine infected with, strain O/SKR/AS/2002 showed typical clinical signs, including gross vesicular lesions in mouth and pedal sites. In addition, FMDV was isolated from, and FMDV genomic RNA was detected in, blood, serum, nasal swabs and oesophageal-pharyngeal (OP) fluid early in the course of infection. Antibodies against the non-structural protein (NSP) 3ABC were detected in both directly inoculated and contact pigs, indicating active virus replication. In contrast, the disease in cattle was atypical. After inoculation, lesions were confined to the infection site. A transient viraemia occurred 1 and 2 days after inoculation, and this was followed by the production of antibodies to NSP 3ABC, indicating subclinical infection. No clinical disease was seen, and no antibodies to NSP 3ABC were present in contact cattle. Additionally, no virus or viral nucleic acid was detected in blood, nasal swab and OP fluid samples from contact cattle. Thus, the virus appeared not to be transmitted from infected cattle to contact cattle. In its behaviour in pigs and cattle, strain O/SKR/AS/2002 resembled the porcinophilic FMDV strain of Cathay origin, O/TAW/97. However, the latter, unlike O/SKR/AS/2002, has reduced ability to grow in bovine-derived cells. The porcinophilic character of O/TAW/97 has been attributed to a deletion in the 3A coding region of the viral genome. However, O/SKR/AS/2002 has an intact 3A coding region.

Neurogastroenterology of tegaserod (HTF 919) in the submucosal division of the guinea-pig and human enteric nervous system

Actions of the 5-HT(4) serotonergic receptor partial agonist, tegaserod, were investigated on mucosal secretion in the guinea-pig and human small intestine and on electrophysiological behaviour of secretomotor neurons in the guinea-pig small intestinal submucosal plexus. Expression of 5-HT(4) receptor protein and immunohistochemical localization of the 5-HT(4) receptor in the submucosal plexus in relation to expression and localization of choline acetyltransferase and the vesicular acetylcholine (ACh) transporter were determined for the enteric nervous system of human and guinea-pig small intestine. Immunoreactivity for the 5-HT(4) receptor was expressed as ring-like fluorescence surrounding the perimeter of the neuronal cell bodies and co-localized with the vesicular ACh transporter. Exposure of mucosal/submucosal preparations to tegaserod in Ussing chambers evoked increases in mucosal secretion reflected by stimulation of short-circuit current. Stimulation of secretion had a relative high EC(50) of 28.1 +/- 1.3 mumol L(-1), was resistant to neural blockade and appeared to be a direct action on the secretory epithelium. Tegaserod acted at presynaptic 5-HT(4) receptors to facilitate the release of ACh at nicotinic synapses on secretomotor neurons in the submucosal plexus. The 5-HT(2B) receptor subtype was not involved in actions at nicotinic synapses or stimulation of secretion.

Sources and outcome of bloodstream infections in cancer patients: the role of central venous catheters

Simultaneously drawn quantitative blood cultures are used to diagnose catheter-related bloodstream infections. We conducted this study to determine the frequency with which central venous catheters were the source of bloodstream infections detected through paired positive blood cultures drawn from cancer patients and the potential for quantitative blood cultures to help predict outcome in neutropenic and non-neutropenic patients. From September 1999 to November 2000, we identified 169 patients with bloodstream infections. Of all bloodstream infections, 56% were catheter-related bloodstream infections. Gram-positive bacteremia was found to be catheter-related in 55% and 69% of patients with hematologic malignancy and solid tumors, respectively, whereas gram-negative bacteremia was catheter-related in only 19% of patients with underlying hematologic malignancy and in 60% of patients with solid tumor (P = 0.01). By multivariate analysis, poor response was associated with critical illness and persistent neutropenia (P < 0.01). In neutropenic patients with catheter-related bloodstream infections, peripheral quantitative blood cultures of >or=100 CFU/mL was also associated with poor response (P = 0.05). Central venous catheters were the major source of bloodstream infection, particularly in patients with solid tumors. In addition to critical illness and persistent neutropenia, quantitative blood cultures might be useful in predicting outcomes for neutropenic patients with catheter-related bloodstream infections.

Surgical outcome after removal of idiopathic macular epiretinal membrane in young patients

PURPOSE

To report the clinical features of the eye of young patients with an idiopathic macular epiretinal membrane (ERM), and the visual outcomes after the surgical removal of the ERM.

METHODS

A retrospective review of the medical records of eight young patients (age, 23-39 years; mean, 32.5 years) with an idiopathic macular ERM was performed. The patients underwent vitrectomy and removal of the ERM with peeling of the internal limiting membrane (ILM). The pre- and postoperative visual acuity and intra- and postoperative complications were investigated.

RESULTS

Ophthalmoscopically, the ERMs in seven eyes were white, opaque, and dense, while one was grayish-white and less dense. A posterior vitreous detachment was not present and the ERM adhered strongly to the underlying retina in all eight eyes. The mean best-corrected visual acuity (BCVA) preoperatively was 20/140 (Snellen; range: 20/250-20/63), and the BCVA improved significantly to 20/30 (range: 20/40-20/20) postoperatively with an average follow-up of 14.6 months (range: 6-42 months; Wilcoxon sign-rank test, P<0.001). An improvement of >7 lines was observed in seven of eight eyes. A recurrence of an ERM without involving the macula was detected in one eye (12.5%).

CONCLUSIONS

The clinical features of the ERMs in young patients are different from those in elderly patients, eg, thicker, more adherent to the retina, and still attached to the vitreous. Vitrectomy and removal of ERM with ILM peeling are effective and safe surgical procedures. Removal of the ILM may minimize the recurrence of an ERM.

The impact of modifiable risk factors on mortality from prostate cancer in populations of the Asia-Pacific region

Mortality from cancer of the prostate is increasing in the Asia-Pacific, when much of this region is undergoing a transition to a Western lifestyle. The role that lifestyle factors play in prostate cancer appears limited, but existing data mainly are from the West. We conducted an individual participant data analysis of 24 cohort studies involving 320,852 men (83% in Asia). Cox proportional hazard models were used to quantify associations between risk factors and mortality from prostate cancer. There were 308 deaths from prostate cancer (14% in Asia) during 2.1 million person-years of follow-up. The age-adjusted hazard ratio (95% confidence interval; CI) for men with body mass index (BMI) 28 kg/m2 or more, compared with below 25, was 1.55 (1.12 - 2.16); no such significant relationship was found for height or waist circumference. The BMI result was unchanged after adjustment for other variables, was consistent between Asia and Australia/New Zealand (ANZ) and did not differ with age. There was no significant relationship with diabetes, glucose or total cholesterol (p > or = 0.18). Smoking, alone, showed different effects in the two regions, possibly due to the relative immaturity of the smoking epidemic in Asia. In ANZ, the multiple-adjusted hazard ratio for an extra 5 cigarettes per day was 1.12 (95%CI: 1.03 - 1.22), whereas in Asia it was 0.77 (0.56 - 1.05). Body size is an apparently important determinant of prostate cancer in the Asia-Pacific. Evidence of an adverse effect of smoking is conclusive only in the predominantly Caucasian parts of the region.

The role of lifestyle risk factors on mortality from colorectal cancer in populations of the Asia-Pacific region

Although colorectal cancer is one of the leading malignancies worldwide, there are few data on aetiological relationships from the Asia-Pacific region. Therefore, a collaborative study was conducted involving over half a million subjects from 33 cohort studies in the region. Age-adjusted death rates from colorectal cancer, over an average of 6.8 years follow-up, were 12 and 14 per 100,000 person-years among Asian women and men, respectively; corresponding values in Australasia were 31 and 41. Height was strongly associated with death from colorectal cancer: an extra 5 cm of height was associated with 10% (95%confidence interval, 3% - 18% additional risk, after adjustment for other factors. Smoking increased risk by 43% (9% - 88%), although no significant dose-response relationship was discerned (p>0.05). Other significant (p <0.05) risk factors were body mass index and lack of physical activity. There was no significant effect on colorectal cancer mortality for alcohol consumption, waist circumference, fasting blood glucose or diabetes, although the latter conferred a notable 26% additional risk. Height may be a biomarker for some currently unknown genetic, or environmental, risk factors that are related both to skeletal growth and mutanogenesis. Understanding such mechanisms could provide opportunities for novel preventive and therapeutic intervention.

HIV-related knowledge, stigma, and willingness to disclose: A mediation analysis

Increasing HIV knowledge is a focus of many HIV education and prevention efforts. While the bivariate relationship of HIV serostatus disclosure with HIV-related knowledge and stigma has been reported in the literature, little is known about the mediation effect of stigma on the relationship of HIV knowledge with HIV serostatus disclosure. Data from 4,208 rural-to-urban migrants in China were analyzed to explore this issue. Overall, 70% of respondents reported willingness to disclose their HIV status if they were HIV-positive. Willingness to disclose was negatively associated with misconceptions about HIV transmission and stigma. Stigma mediated the relationship between misconceptions and willingness to disclose among women but not men. The mediation effect of stigma suggests that stigmatization reduction would be an important component of HIV prevention approaches. Gender inequality needs to be addressed in stigmatization reduction efforts.