***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The delivery of circulating tryptophan to the brain and its conversion to serotonin vary directly with plasma concentrations of tryptophan and inversely with those of other large neutral amino acids ( LNAAs ) . Although carbohydrate-rich , protein-free formula diets have been shown to elevate , and high-protein diets to depress , the tryptophan-LNAA ratio , few data are available about this ratio 's responses to actual meals . OBJECTIVE We determined whether carbohydrate-rich or protein-rich breakfasts , such as those Americans normally eat , produce substantial differences in the plasma tryptophan-LNAA ratio and in the corresponding ratio for tyrosine , the precursor of brain dopamine and norepinephrine . DESIGN Nine overnight-fasted subjects consumed , 3 - 7 d apart , a carbohydrate-rich ( 69.9 g carbohydrate and 5.2 g protein ) and a protein-rich ( 15.4 g carbohydrate and 46.8 g protein ) breakfast . Blood sample s collected at baseline and after 40 , 80 , 120 , and 240 min were assayed for tryptophan , tyrosine , the 5 other LNAAs , and insulin . RESULTS The carbohydrate-rich and protein-rich breakfasts had significantly different effects on both the plasma tryptophan-LNAA and tyrosine-LNAA ratios ( each P < 0.01 ) . Among the 8 subjects who consumed both breakfasts , the median difference for tryptophan : LNAA was 54 % ( range : 36 - 88 % ) and for tyrosine : LNAA was 28 % ( range : 10 - 64 % ) . Insulin concentrations rose significantly after the carbohydrate but not after the protein meal . CONCLUSIONS High-carbohydrate and high-protein breakfasts similar to those Americans normally eat can cause substantial differences in the plasma tryptophan ratio and thus , probably , in brain tryptophan concentrations and serotonin synthesis . Such meals also change the plasma tyrosine ratio and may thereby modify catecholamine synthesis BACKGROUND The relationship between serum cholesterol and cancer incidence remains controversial . PATIENTS AND METHODS We investigated the association of total serum cholesterol ( TSC ) with subsequent  cancer incidence in a population -based cohort of 172 210 Austrian adults prospect ively followed up for a median of 13.0 years .  Cox regression , allowing for time-dependent effects , was used to estimate adjusted hazard ratios ( HRs ) with 95 % confidence intervals ( 95 % CIs ) for the association of TSC with cancer . RESULTS We observed pronounced short-term associations of TSC and overall cancer incidence in both men and women . For malignancies diagnosed shortly ( < 5 months ) after baseline TSC measurement , the highest TSC tertile ( > 235.0 mg/dl in men and > 229.0 in women ) compared with the lowest tertile ( < 194.0 mg/dl in men and < 190.0 in women ) was associated with a significantly lower overall cancer risk [ HR = 0.58 ( 95 % CI 0.43 - 0.78 , P(trend ) = 0.0001 ) in men , HR = 0.69 ( 95 % CI 0.49 - 0.99 , P(trend ) = 0.03 ) in women ] . However , after roughly 5 months from baseline measurement , overall cancer risk was not significantly associated with TSC . The short-term inverse association of TSC with cancer was mainly driven by malignancies of the digestive organs and lymphoid and hematopoietic tissue . CONCLUSION The short-term decrease of cancer risk seen for high levels of TSC may largely capture pre clinical effects of cancer on TSC Background : Body mass index ( BMI ) has been linked with both increased and decreased risk of suicide attempts and deaths . Methods : In a prospect i ve cohort study of 1.1 million adults , participants reported their anthropometric and other characteristics in 1982 . Participants were followed for cause-specific mortality through 2004 . Results : A total of 2231 participants died of suicide during 21.6 million person-years of follow-up . Compared with a BMI of 18.5–22.9 kg/m2 , adjusted hazard ratios for completed suicide were 0.99 ( 95 % confidence interval = 0.72–1.37 ) , 0.78 ( 0.69–0.88 ) , 0.73 ( 0.65–0.82 ) , 0.72 ( 0.62–0.83 ) , 0.77 ( 0.65–0.92 ) , and 0.55 ( 0.36–0.83 ) for BMI values < 18.5 , 23.0–24.9 , 25.0–27.4 , 27.5–29.9 , 30.0–34.9 , and ≥35.0 kg/m2 , respectively . The relationship was consistent among men and women and across geographic regions , but was limited to married individuals ( test for interaction , P = 0.009 ) . Conclusions : The risk of death from suicide is inversely related to BMI in middle-aged and older adults Data from the Third National Health and Nutrition Examination Survey ( 1988 - 1994 ) were used to examine the relation between obesity and depression .  Past-month depression was defined using criteria from the Diagnostic and Statistical Manual of Mental Disorders , Third Edition , and was measured with the Diagnostic Interview Schedule . Obesity was defined as a body mass index ( weight (kg)/height (m)2 ) of 30 or higher . The authors compared risks of depression in obese and normal-weight ( body mass index 18.5 - 24.9 ) persons . Obesity was associated with  past-month depression  in women ( odds ratio (OR)=1.82 , 95 % confidence interval ( CI ) : 1.01 , 3.3 ) but was not significantly associated in men ( OR=1.73 , 95 % CI : 0.56 , 5.37 ) . When obesity was stratified by severity , heterogeneity in the association with depression was observed . Class 3 ( severe ) obesity ( body mass index > or = 40 ) was associated with past-month depression in unadjusted analyses ( OR=4.98 , 95 % CI : 2.07 , 11.99 ) ; the association remained strong after results were controlled for age , education , marital status , physician 's health rating , dieting for medical reasons , use of psychiatric medicines , cigarette smoking , and use of alcohol , marijuana , and cocaine . These findings suggest that obesity is associated with depression mainly among persons with severe obesity . Prospect i ve studies will be necessary to clarify the obesity-depression relation but await the identification of potential risk factors for depression in the obese BACKGROUND Body mass index ( BMI ; calculated as weight in kilograms divided by height in meters squared ) has been linked to depression and the risk of suicide attempts and deaths in conflicting directions . METHODS In a prospect i ve cohort study of 46 755 men free of cancer enrolled in the Health Professionals Follow-up Study , participants reported their height , weight , diet , and physical activity on repeated occasions beginning in 1986 and were followed up until death or until February 2002 . A sub sample of 1829 men reported their  mental health-related quality of life with the  Mental Component Summary Scale of the  36-Item Short-Form Health Survey in 1998 . RESULTS A total of 131 men died from suicide during follow-up . A higher BMI was related to a grade d decline in the suicide mortality rate , from 52 per 100 000 person-years among men with a BMI of less than 21 to 13 per 100 000 among men with a BMI of 30 or higher ; the adjusted hazard ratio per 1-U BMI increment was 0.89 ( 95 % confidence interval , 0.84 - 0.95 ; P<.001 ) . The relationship was consistent when baseline or up date d measures of BMI were used and with adjustment for medical illness , dietary factors , antidepressant use , physical activity , or social support . Height and physical activity were not strongly associated with risk . Analyses of mental health-related quality of life showed a similar positive relationship with BMI . CONCLUSIONS Among men , risk of death from suicide is strongly inversely related to BMI , but not to height or to physical activity . Although obesity can not be recommended on the basis of its detrimental effects , further research into the mechanisms of lower risk among overweight and obese men may provide insights into effective methods of suicide prevention Objectives : To assess the risk of mortality from suicide among male veteran participants in a large population -based health survey . Design and setting : A prospect i ve follow-up study in the US . Data were obtained from the US National Health Interview Surveys 1986–94 and linked to the Multiple Cause of Death file ( 1986–97 ) through the National Death Index . Participants : The sample comprised 320 890 men , aged ≥18 years at baseline . The participants were followed up with respect to mortality for 12 years . Results : Cox proportional hazards analysis showed that veterans who were white , those with ≥12 years of education and those with activity limitations ( after adjusting for medical and psychiatric morbidity ) were at a greater risk for completing suicide . Veterans were twice as likely ( adjusted hazard ratio 2.04 , 95 % CI 1.10 to 3.80 ) to die of suicide compared with non-veterans in the general population . The risk of death from “ natural ” causes ( diseases ) and the risk of death from “ external ” causes did not differ between the veterans and the non-veterans . Interestingly , male veterans who were overweight had a significantly lower risk of completing suicide than those who were of normal weight . Conclusions : Veterans in the general US population , whether or not they are affiliated with the Department of Veterans Affairs ( VA ) , are at an increased risk of suicide . With a projected rise in the incidence of functional impairment and psychiatric morbidity among veterans of the conflicts in Afghanistan and Iraq , clinical and community interventions that are directed towards patients in both VA and non-VA healthcare facilities are needed The purpose of this study was to evaluate whether elements signifying relative insulin sensitivity ( IS ) were prospect ively linked to accidents and suicides in 14,976 Helsinki Heart Study ( HHS ) screenees . The main outcome measure was hospitalizations and deaths from accidents and suicide attempts determined from Finnish registries , in aggregate ; and separating out suicides ( and attempts ) . Cox proportional hazards regression was used to determine adjusted risk ratios ( RR ) relating IS characteristics ( extreme quartiles of high HDL-C , low BMI , and low SBP ) , individually and conjointly , to subsequent accidents or suicides ( including attempts ) , adjusted for age , alcohol use , smoking , and non-HDL cholesterol . Each IS element was related to combined hospitalization and death , from accidents and from suicide attempts ; increasing numbers of these characteristics were associated with increased risk , an effect that was more powerful and statistically significant for suicide . For accidents , the presence of one and two to three IS characteristics provided RRs ( 95 % confidence intervals ( CI ) ) of 1.08 ( 0.97 - 1.20 ) and 1.14 ( 0.98 - 1.31 ) , respectively . For suicides including attempts , RRs ( 95%CI ) were 1.61 ( 1.09 - 2.38 ) for one IS factor , and 1.88 ( 1.18 - 2.98 ) for two to three IS factors , while for completed suicides , the figures were 2.01 ( 1.19 - 3.38 ) and 2.24 ( 1.20 - 4.17 ) , respectively . We speculate that insulin sensitivity may relate to these outcomes through low central serotonin activity BACKGROUND With increased efforts to lower serum cholesterol levels , it is important to quantify associations between serum cholesterol level and causes of death other than coronary heart disease , for which an etiologic relationship has been established . METHODS For an average of 12 years , 350,977 men aged 35 to 57 years who had been screened for the Multiple Risk Factor Intervention Trial were followed up following a single st and ardized measurement of serum cholesterol level and other coronary heart disease risk factors ;  21,499 deaths were identified . RESULTS A strong , positive , grade d relationship was evident between serum cholesterol level measured at initial screening and death from coronary heart disease . This relationship persisted over the 12-year follow-up period . No association was noted between serum cholesterol level and stroke . The absence of an association overall was due to different relationships of serum cholesterol level with intracranial hemorrhage and nonhemorrhagic stroke . For the latter , a positive , grade d association with serum cholesterol level was evident . For intracranial hemorrhage , cholesterol levels less than 4.14 mmol/L ( less than 160 mg/dL ) were associated with a twofold increase in risk . A serum cholesterol level less than 4.14 mmol/L ( less than 160 mg/dL ) was also associated with a significantly increased risk of death from cancer of the liver and pancreas ; digestive dise 
    Output:
    
Overall , among men , a high BMI was associated with a low risk of attempted or completed suicide .
There was a paradox among women , namely , a high BMI was associated with an elevated risk of attempted suicide but a low risk of completed suicide .