***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: The salivary enzyme alpha-amylase has been proposed to indicate stress-reactive bodily changes . A previous study by the authors revealed marked increases in salivary alpha-amylase following psychosocial stress , indicating a stress-dependent activation of salivary alpha-amylase . Salivary alpha-amylase has been suggested to reflect catecholaminergic reactivity . Our aim was to assess/evaluate a possible relationship between salivary alpha-amylase and adrenergic parameters , i.e. catecholamines , as well as other stress markers . Using an intra-individual repeated measures design , 30 healthy young men underwent the Trier Social Stress Test ( TSST )  , which consists of a mental arithmetic task and free speech in front of an audience and a control condition in r and omized order .  Salivary alpha-amylase and salivary cortisol as well as plasma catecholamines and cardiovascular activity were repeatedly measured before , during , and after both conditions . Significant differences were found between the stress and the rest condition in salivary alpha-amylase , salivary cortisol , plasma catecholamines , and cardiovascular parameters ( heart rate , LF , HF , LF/HF ) . However , general alpha-amylase responses ( area under the curve ) were not associated with general responses in catecholamines and cortisol in the stress condition ( r smaller than 0.25 for all analyses ) . Analysis of cardiovascular parameters indicates a positive relationship between amylase and sympathetic tone ( LF/HF ) during stress . Salivary alpha-amylase is sensitive to psychosocial stress . Since it does not seem to be closely related to other biological stress markers such as catecholamines and cortisol , salivary alpha-amylase may be a useful additional parameter for the measurement of stress Background Green tea is one of the most popular beverages worldwide . This review summarizes the beneficial effects of green tea on cancer prevention . Methods Electronic data bases , including PubMed ( 1966–2008 ) , the Cochrane Library ( Issue 1 , 2008 ) and Chinese Biomedical Data base ( 1978–2008 ) with supplement of relevant websites , were search ed . There was no language restriction . The search es ended at March 2008 . We included r and omized and non-r and omized clinical trials , epidemiological studies ( cohort and case-control ) and a meta- analysis . We excluded case series , case reports , in vitro and animal studies . Outcomes were measured with estimation of relative risk , hazard or odd ratios , with 95 % confidence interval . Results Forty-three epidemiological studies , four r and omized trials and one meta- analysis were identified . The overall quality of these studies was evaluated as good or moderate . While some evidence suggests that green tea has beneficial effects on gastrointestinal cancers , the findings are not consistent . Conclusion Green tea may have beneficial effects on cancer prevention . Further studies such as large and long term cohort studies and clinical trials are warranted L-Theanine is an amino acid found naturally in tea . Despite the common consumption of L-theanine , predominantly in combination with caffeine in the form of tea , only one study to date has examined the cognitive effects of this substance alone , and none have examined its effects when combined with caffeine . The present r and omised , placebo-controlled , double-blind , balanced crossover study investigated the acute cognitive and mood effects of L-theanine ( 250 mg ) , and caffeine ( 150 mg ) , in isolation and in combination . Salivary caffeine levels were co-monitored . L-Theanine increased ' headache ' ratings and decreased correct serial seven subtractions . Caffeine led to faster digit vigilance reaction time , improved Rapid Visual Information Processing ( RVIP ) accuracy and attenuated increases in self-reported ' mental fatigue ' . In addition to improving RVIP accuracy and ' mental fatigue ' ratings , the combination also led to faster simple reaction time , faster numeric working memory reaction time and improved sentence verification accuracy . ' Headache ' and ' tired ' ratings were reduced and ' alert ' ratings increased . There was also a significant positive caffeine x L-theanine interaction on delayed word recognition reaction time . These results suggest that beverages containing L-theanine and caffeine may have a different pharmacological profile to those containing caffeine alone OBJECTIVE L-theanine is a unique amino acid present almost exclusively in the tea plant . It possesses neuroprotective , mood-enhancing , and relaxation properties . This is a first study design ed to evaluate the efficacy and tolerability of L-theanine augmentation of antipsychotic treatment of patients with chronic schizophrenia and schizoaffective disorder . METHOD 60 patients with DSM-IV schizophrenia or schizoaffective disorder participated in an 8-week , double-blind , r and omized , placebo-controlled study . 400 mg/d of L-theanine was added to ongoing antipsychotic treatment from February 2006 until October 2008 . The outcome measures were the Positive and Negative Syndrome Scale ( PANSS ) , the Hamilton Anxiety Rating Scale ( HARS ) , the Cambridge Neuropsychological Test Automated Battery ( CANTAB ) for neurocognitive functioning , and additional measures of general functioning , side effects , and quality of life . RESULTS 40 patients completed the study protocol . Compared with placebo , L-theanine augmentation was associated with reduction of anxiety ( P = .015 ; measured by the HARS scale ) and positive ( P = .009 ) and general psychopathology ( P < .001 ) scores ( measured by the PANSS 3-dimensional model ) . According to the 5-dimension model of psychopathology , L-theanine produced significant reductions on PANSS positive ( P = .004 ) and activation factor ( P = .006 ) scores compared to placebo . The effect sizes ( Cohen d ) for these differences ranged from modest to moderate ( 0.09 - 0.39 ) . PANSS negative and CANTAB task scores , general functioning , side effect , and quality of life measures were not affected by L-theanine augmentation . L-theanine was found to be a safe and well-tolerated medication . CONCLUSIONS L-theanine augmentation of antipsychotic therapy can ameliorate positive , activation , and anxiety symptoms in schizophrenia and schizoaffective disorder patients . Further long-term studies of L-theanine are needed to substantiate the clinical ly significant benefits of L-theanine augmentation Abstract . Rationale : Pre- clinical and clinical investigations have provided a great deal of evidence that the fear-potentiated startle paradigm represents a valid model for the objective assessment of emotional states of anxiety and fear .  Objective : The four studies presented in this report sought to further vali date the " threat of shock " paradigm as a human analogue to fear-potentiated startle in rats , by examining the effect of benzodiazepine administration on both baseline and fear-potentiated startle . Methods : Three studies , conducted at Utrecht University , evaluated the effects of oxazepam and of diazepam on baseline and fear-potentiated startle , whereas a fourth study , conducted at Yale University , evaluated the effect of diazepam on baseline , context ual and cue-specific fear-potentiated startle . The threat of shock paradigm consisted of verbal instruction about two visual cues ( the threat cue predicted the possible administration of electric shock , the other predicted a safe period ) , followed by a series of presentations of these cues . During these conditions , acoustic startle stimuli were presented in order to elicit startle responses . The magnitude of the startle response was used to index the degree of fear or alarm experienced during the periods of threat and safety . The fourth study examined the effect of IV administration of diazepam in a similar threat of shock paradigm except that there were two additional context manipulations : electrode placement and darkness . Results : None of the drug manipulations affected specific threat-cue potentiation of startle . However , reductions in baseline startle were observed . Further , startle potentiation by darkness was inhibited by diazepam . Conclusions : At least one type of fear-potentiated startle , i.e. potentiation by a cue-specific fear manipulation , is not susceptible to benzodiazepine treatment . In contrast , effects of manipulations more akin to anxiety ( darkness , context ) appear sensitive to benzodiazepines . Human experimental models differentiating between these cue specific and context ual responses are needed to shed more light on differences in the anatomy and pharmacology of anxiety disorders The objective of the project was to determine the effects of tea ( Camellia sinensis ) leaf beverage consumption on the apparent utilization of niacin , thiamin , and protein in human subjects . During two r and omly arranged experimental periods of 14 days each , 10 adult female human subjects were fed a constant ( same foods each day ) , measured , laboratory-controlled diet . Tea was fed during one period while no tea was allowed during the other period . A dehydrated black tea infusion product ( instant tea , 8 g/subject/day/dry weight basis ) was used which subjects were allowed to dilute in water . Subjects made complete collection s of urine and stools . Fasting blood sample s were drawn at the end of each experimental period . No effects on protein status were demonstrated . Urinary thiamin losses were depressed with the use of tea but niacin losses were increased . Blood serum concentrations of thiamin diphosphate also were depressed during the tea drinking period as compared to values during the non-tea period . No significant effect on blood serum levels of nicotinaminde or N′-methylnicotinamine were found but values tended to be lower during the tea than the non-tea period . These results suggest that tea consumption inhibits the utilization of thiamin . However , niacin availability was unaffected by tea drinking . Because of the decreased availability of thiamin , the need for niacin was depressed which caused a greater than expected urinary loss of this vitamin Rationale Although both contain behaviourally significant concentrations of caffeine , tea is commonly perceived to be a less stimulating drink than coffee . At least part of the explanation for this may be that theanine , which is present in tea but not coffee , has relaxing effects . There is also some evidence that theanine affects cognitive performance , and it has been found to reduce blood pressure in hypertensive rats . Objectives To study the subjective , behavioural and blood pressure effects of theanine and caffeine administered alone and together , in doses relevant to the daily tea consumption of regular tea drinkers . Material s and methods In a r and omised , double-blind , placebo-controlled study , healthy adult participants ( n = 48 ) received either 250-mg caffeine , 200-mg theanine , both or neither of these . They completed ratings of mood , including anxiety , and alertness , and had their blood pressure measured before and starting 40 min after drug administration . Anxiety was also assessed using a visual probe task . Results Caffeine increased self-rated alertness and jitteriness and blood pressure . Theanine antagonised the effect of caffeine on blood pressure but did not significantly affect jitteriness , alertness or other aspects of mood . Theanine also slowed overall reaction time on the visual probe task . Conclusions Theanine is a physiologically and behaviourally active compound and , while it is unclear how its effects might explain perceived differences between tea and coffee , evidence suggests that it may be useful for reducing raised blood pressure L-Theanine ( delta-glutamylethylamide ) is one of the predominant amino acids ordinarily found in green tea , and historically has been used as a relaxing agent . The current study examined the acute effects of L-theanine in comparison with a st and ard benzodiazepine anxiolytic , alprazolam and placebo on behavioural measures of anxiety in healthy human subjects using the model of anticipatory anxiety ( AA ) . Sixteen healthy volunteers received alprazolam ( 1 mg ) , L-theanine ( 200 mg ) or placebo in a double-blind placebo-controlled repeated measures design . The acute effects of alprazolam and L-theanine were assessed under a relaxed and experimentally induced anxiety condition . Subjective self-reports of anxiety including BAI , VAMS , STAI state anxiety , were obtained during both task conditions at pre- and post-drug administrations . The results showed some evidence for relaxing effects of L-theanine during the baseline condition on the tranquil-troubled subscale of the VAMS . Alprazolam did not exert any anxiolytic effects in comparison with the placebo on any of the measures during the relaxed state . Neither L-theanine nor alprazalam had any significant anxiolytic effects during the experimentally induced anxiety state . The findings suggest that while L-theanine may have some relaxing effects under resting conditions , neither L-theanine not alprazolam demonstrate any acute anxiolytic effects under conditions of increased anxiety in the AA model INTRODUCTION The purpose of this study was to investigate the efficacy and safety of L-theanine as an aid to the improvement of objective ly measured sleep quality in a population of 98 male children formally diagnosed with attention-deficit/hyperactivity disorder ( ADHD ) . METHODS A r and omized , double-blind , placebo-controlled trial was conducted involving boys , ages 8 - 12 years , who had been previously diagnosed with ADHD . An experienced physician confirmed the diagnosis of ADHD in each subject . R and omization was stratified based upon current use of stimulant medication to ensure an equal distribution of stimulant/non-stimulant treated subjects into active and placebo treated groups . Participants consumed two chewable tablets twice daily ( at breakfast and after school ) , with each tablet containing 100 mg of L-theanine ( total 400 mg daily Suntheanine ® , Taiyo Kagaku 
    Output:
    
Our findings suggest that supplementation of 200–400 mg/day of L-THE may assist in the reduction of stress and anxiety  in people exposed to stressful conditions .