两种氨基酸和三种遗传病

蛋白质的基本结构单位是氨基酸，组成蛋白质的氨基酸约有20种，其中8种在人体内不能制造，必需从食物中获得，叫必需氨基酸，苯丙氨酸是其中之一。苯丙氨酸在人体相关酶的作用下，可以转化成酪氨酸。如果由于基因缺陷，苯丙氨酸和酪氨酸代谢异常则会产生：黑尿病（黑的）、白化病（白的）、苯丙酮尿症（呆的）3种遗传病。     

人类遗传病与优生

人类遗传病与优生１．人类的疾病可分为四大类：（１）完全由遗传因素决定，看不出特定的环境因素是发病所必需的。如白化病。（２）基本上由遗传因素决定，但需要环境中一定的诱因才发病。如苯丙酮尿症。（３）遗传因素和环境对发病都有作用，作用的大小，可以互不相同，...     

氨基酸代谢与运动能力的关系

尽管氨基酸在运动过程中提供的能量很少,但它却与运动能力有密切的关系。本文着重论述了运动性疲劳与GABA和芳香族氨基酸的关系以及补充支链氨基酸可推迟疲劳产生的机制。同时还探讨了运动对氨基酸代谢的影响,包括葡萄糖──丙氨酸循环及其意义,各类运动条件下的氨基酸代谢状况。最后,本文还讨论了适当补充氨基酸与运动能力的关系和补充Gln对由于运动引起的免疫系统功能变化的影响。     

关于必需氨基酸的一个问题

1问题的提出 在学习人教版高中《生物》教材“人和动物体内三大营养物质代谢”时，学生通过教材叙述和教师讲解已得知组成人体蛋白质的氨基酸有20种，其中有8种必需氨基酸和12种非必需氨基酸。在分析人体内氨基酸来源时，除了分解食物中的蛋白质得到氨基酸和氨基转换作用外，还可以通过自身蛋白分解产生。基于上述认识有学生提出了疑惑：既然体内是可以产生必需氨基酸的，那为什么还叫“必需氨基酸”呢，并猜测：可能由于自身蛋白质分解得到的必需氨基酸量不够用，需要从外界摄入才叫必需氨基酸。     

“现代生物科技专题”常见疑点小结

1．用于基因诊断的疾病 目前四大类疾病可以通过基因进行诊断：由单个基因突变引起的疾病；常见病和多发病（多是多个基因引起的，如糖尿病、心脏病等）；癌症（抑癌基因或癌基因异常）；感染性疾病（SARS、禽流感等外源性基因）。治疗现状：目前已经有千种单基因病、几十种染色体病和近百种代谢缺陷症能用此种方法进行明确诊断；目标是开发简便、高效的多种疾病同步检测技术。     

一分钟解惑

孩子头发黄,是受基因影响 头发颜色主要是受基因影响,而不是营养.并且有些人幼年时的发色比成年期要浅,这可能也是“黄毛丫头”这个叫法的由来. 此外,日光暴晒也可引起发色的轻度改变.少数确因营养缺陷所致的发色异常,也主要见于部分涉及营养代谢的先天性疾病,例如苯丙酮尿症,而非大家常说的“营养不良”.     

真菌毒素

一、真菌毒素及其危害性真菌毒素是真菌产生的代谢产物。由真菌毒素引起的人和动物的疾病,统称为真菌毒素中毒症。历史上对真菌毒素中毒症早有报导,由麦角菌侵染小麦产生的麦角碱,是最早知道的真菌毒素之一,但当时对真菌毒素及其中毒症的研究却重视不够。直到1960年在英国发生一起十万只火鸡患肝脏疾病而死亡的事件,才引起有关方面的重视。这是由于饲料中含有发霉的花生而造成的牲畜中毒。经过检查发现在霉花生中黄曲霉是数量最多的微生物。黄曲霉能产生一种具有萤光的物质,是致病的所在。科     

菌星─香菇

在我国香菇历来是医食两用的食用菌．90年代日本掀起了“香菇热”，香菇被誉为理想的保健营养与太空食品的“菌星”．据现代科学研究证明，香菇不仅具有浓郁香味，而且含有丰富的蛋白质、脂肪、碳水化合物、矿物质、维生素、微量元素．香菇子实体蛋白质中氨基欧共有16种，对人体必需的8种氨基酸中，香菇就含有7种，引起人们重视的是在香菇内发现一种尚未被所知的氨基酸，其药用成分使香菇的热量几乎近于零，从而使香菇成为名副其实的高蛋白、低能量的保健营养和药用的食品．香菇对降低人体胆固醇，改善人体缺酶症和防癌也具重要作用．菌星─…     

苯丙氨酸代谢性遗传疾病

苯丙氨酸是人体需要从食物中摄取的一种必需氨基酸。它在人体内除了一部分用以合成组织蛋白质外,其余的部分在各种酶的作用下,通过氧化反应进行代谢。如果在代谢过程中缺少某种酶的作用,则会导致苯丙氨酸代谢异常,从而产生代激性疾病。在高中《生物》教材、教参（必修）中涉及到的白化病、苯丙酮尿症以及在日常生活中可能遇见的黑尿症,它们均为苯丙氨酸代谢过程中,缺乏某种相应的酶而产生的常染色体隐性遗传病。苯丙氨酸的代谢途径可简图表示如下1、白化病在正常情况下,苯丙氨酸可转化为酪氨酸,酪氨酸经过酪氨酸酶的催化作用,最后…     

冬季日粮与水牛血红蛋白尿关系的研究

水牛血红蛋白尿主要是水牛冬季日粮中缺磷，而水《对磷的需要量增加，导致血磷水平降低，糖代谢障碍，细胞内三磷酸腺苷（ＡＴＰ）生成和供给不足，影响了红细胞膜的结构和功能，引起急性血管内溶血的一种代谢性疾病．临床上采用补充ＡＴＰ和磷的治疗方法，疗效十分显著。     

Maternal Depressive Symptoms During the Pre- and Postnatal Periods and Infant Attention to Emotional Faces

We examined how infants’ attentional disengagement from happy, fearful, neutral, and phase-scrambled faces at 8 months, as assessed by eye tracking, is associated with trajectories of maternal depressive symptoms from early pregnancy to 6 months postpartum (decreasing n = 48, increasing n = 34, and consistently low symptom levels n = 280). The sample (mother–infant dyads belonging to a larger FinnBrain Birth Cohort Study) was collected between 5/2013–6/2016. The overall disengagement probability from faces to distractors was not related to maternal depressive symptoms, but fear bias was heightened in infants whose mothers reported decreasing or increasing depressive symptoms. Exacerbated attention to fearful faces in infants of mothers with depressive symptoms may be independent of the timing of the symptoms in the pre- and postnatal stages.     

DHA对婴幼儿的生理作用及应用研究

DHA属n-3系多不饱和脂肪酸,俗称"脑黄金".属于一种人体的必需多元不饱和脂肪酸,是大脑和视网膜的重要构成部分,也是婴幼儿神经系统发育的必须营养物质,对智力和视力发育起着至关重要的作用.本文综述了DHA的主要来源、对婴幼儿的生理功能以及在婴幼儿食品中的应用.     

Behavioral and physiological responsivity, sleep, and patterns of daily cortisol production in infants with and without colic

To describe the behavioral and physiological responses associated with colic, the responses of 20 two-month-old infants with and 20 without colic were studied during a physical examination. Parents kept a diary of infant behaviors (including crying and fussing) for 3 days following the visit. Using Wessel, Cobb, Jackson, Harris, & Detwiler criteria, colic was defined as fussing/crying for 3 hr or more on each of the 3 days. Behavioral data coded by "blind" observers showed that during the physical exam, colic infants cried twice as much, cried more intensely, and were more inconsolable than were control infants. Despite these behavioral differences, heart rate, vagal tone, and cortisol measures indicated no appreciable difference in physiological responsivity for the two groups. At home, parents collected saliva cortisol samples at wakeup, midmorning, midafternoon, and evening for 2 days. In a finding similar to that shown by the laboratory data, the colic and control infants did not have different levels of daily average cortisol. These laboratory and home data provide no evidence of greater responsivity in the physiological substrate of difficult temperament for colic infants and are consistent with evidence of similarity in temperament once colic is resolved. At home, compared with control infants, colic infants did display a blunted rhythm in cortisol production. By diary, they also slept about 2 hr less per day than did control infants. Nighttime sleep was still significantly different when fussing/crying was statistically controlled. These data suggest that colic might be associated with a disruption or delay in the establishment of the circadian rhythm in activity of the hypothalamic-pituitary-adrenocortical axis and associated sleep-wake activity.     

Mother–Infant Vagal Regulation in the Face-To-Face Still-Face Paradigm Is Moderated by Maternal Sensitivity

Parents' physiological regulation may support infants' regulation. Mothers ( N = 152) and 6-month-old male and female infants were observed in normal and disrupted social interaction. Affect was coded at 1-s intervals and vagal tone measured as respiratory sinus arrhythmia (RSA). Maternal sensitivity was assessed in free play. Mothers and infants showed opposite patterns of RSA change. During disrupted interaction, mothers' RSA increased and infants' decreased, suggesting self-regulation of distress. During reunion, although the typical pattern was for infants to return to baseline levels, infants of sensitive mothers and sensitive mothers both showed a significant decrease in RSA from baseline. Mothers' and infants' physiological responses may be a function of mutual responsiveness.     

Are there long-term consequences of pain in newborn or very young infants?

Physiologic studies indicate that very early pain or stress experiences have more than immediate consequences for infants. Assessment and care of pain are complex subjects made even more complex and challenging when the individual experiencing pain is a very young infant. This review provides evidence that significant and long-lasting physiological consequences may follow painful insults in the very young, including changes in the central nervous system and changes in responsiveness of the neuroendocrine and immune systems to stress at maturity.     

Posttraumatic symptoms among maltreated youth using classification and regression tree analysis

Individual psychological factors have been shown to exacerbate risk for posttraumatic stress disorder (PTSD) symptoms in youth following maltreatment, but the novel contribution of the present study includes a focus on interactive relationships between these factors on specific PTSD symptom clusters. This study identified maltreated youth at highest risk for re-experiencing, avoidance, and hyperarousal symptom clusters via cognitive, affective, and demographic variables. Participants (n = 400) included ethnically diverse maltreated youth. Classification and regression tree (CART) analysis, a form of binary recursive partitioning (BRP), identified subgroups of maltreated youth at highest risk for three core PTSD symptom clusters. Posttraumatic cognitions, anhedonia, negative mood, processing speed, and ethnicity best predicted re-experiencing symptoms. Depersonalization/derealization, verbal comprehension, sexual maltreatment, and age best predicted avoidance symptoms. Negative cognitions about self, IQ, dissociation, working memory, and posttraumatic cognitions best predicted hyperarousal symptoms. Core PTSD symptom clusters may thus be associated with unique collections of risk factors for maltreated youth. Clinical protocols for this population could be recalibrated to be more sensitive to specific profiles that more accurately identify highest risk maltreated youth and better inform evidence-based treatment practices.     

Factors predicting PTSD, depression, and dissociative severity in female treatment-seeking childhood sexual abuse survivors

OBJECTIVE: Two main questions were asked: (1) what abuse characteristics relate to PTSD, depressive, and dissociative severity in adult survivors of child sexual abuse (CSA); and (2) what abuse characteristics influence the severity of dissociation during CSA. METHOD: 89 female CSA survivors' current symptoms of PTSD, depression, and dissociation were assessed with standardized measures. Additionally, abuse characteristics (e.g., age of onset, peritraumatic dissociation) were assessed with a structured interview. RESULTS: Correlational analyses indicated that peritraumatic dissociation was most strongly related to all three types of symptom severity. Additional posthoc correlational analyses revealed that women who experienced penile penetration, believed someone/thing else would be killed, and/or were injured as a result of the abuse exhibited more severe peritraumatic dissociation. Regression analyses indicated that peritraumatic dissociation was the only variable to significantly predict symptom severity across symptom type or disorder. Furthermore, different abuse characteristics predicted adult symptom severity and peritraumatic dissociation. CONCLUSIONS: The relation between peritraumatic dissociation and adult symptomatology was most intriguing and has two main clinical implications: (1) teaching engagement strategies to some CSA survivors in hopes of containing dissociative symptoms immediately following the abuse and (2) the inclusion of exposure-based interventions in the treatment of some adult CSA survivors where indicated.     

生理学“线粒体DNA突变”研究的新进展

生理学中“线粒体DNA(mtDNA)”研究近年来取得重大进展 ,学者们十分关注它的突变与人类疾病的关系。本文综述了mtDNA的结构 ,遗传特点 ,突变类型和几种常见的综合症及临床症状 ,力求展示出研究的新进展     

The role of person familiarity in young infants' perception of emotional expressions

This research investigated the role of person familiarity in the ability of 3.5-month-old infants to recognize emotional expressions. Infants (N = 72) were presented simultaneously with two filmed facial expressions, happy and sad, accompanied by a single vocal expression that was concordant with one of the two facial expressions. Infants' looking preferences and facial expressions were coded. Results indicated that when the emotional expressions were portrayed by each infant's own mother, infants looked significantly longer toward the facial expressions that were accompanied by affectively matching vocal expressions. Infants who were presented with emotional expressions of an unfamiliar woman did not. Even when a brief delay was inserted between the presentation of facial and vocal expressions, infants who were presented with emotional expressions of their own mothers looked longer at the facial expression that was sound specified, indicating that some factor other than temporal synchrony guided their looking preferences. When infants viewed the films of their own mothers, they were more interactive and expressed more positive and less negative affect. Moreover, infants produced a greater number of full and bright smiles when the sound-specified emotion was "happy," and particularly when they viewed the happy expressions of their own mothers. The average duration of negative affect was significantly longer for infants who observed the unfamiliar woman than for those who observed their own mothers. These results show that when more contextual information-that is, person familiarity-was available, infants as young as 3.5 months of age recognized happy and sad expressions. These findings suggest that in the early stages of development, infants are sensitive to contextual information that potentially facilitates some of the meaning of others' emotional expressions.     

Coordinating attention to people and objects in mother-infant and peer-infant interaction

In a longitudinal study, infants 6-18 months of age were observed in their homes playing with their mothers and with peers. Of primary concern was how they coordinated their attention to people and objects. Observations were coded using a state-based scheme that included a state of coordinated joint engagement as well as states of person engagement, object engagement, onlooking, and passive joint engagement. All developmental trends observed were similar regardless of partner: person engagement declined with age, while coordinated joint engagement increased. Passive joint engagement, object engagement, and onlooking did not change with age. However, the absolute amount of some engagement states was affected by partner: both passive and coordinated joint engagement were much more likely when infants played with mothers. We conclude that mothers may indeed support or "scaffold" their infants' early attempts to embed objects in social interaction, but that as attentional capabilities develop even quite unskilled peers may be appropriate partners for the exercise of these capacities.