精原干细胞移植后的体内迁移、增殖和分化**☆

a背景：精原干细胞移植对男性不育的治疗具有潜在的临床应用价值,但移植后干细胞体内迁移、增殖、分化的过程目前尚不完全清楚。 目的：观测精原干细胞移植后的体内迁移、增殖和分化过程。 方法：以出生后6~10 d的雄性C57BL/6小鼠为供体,通过复合酶消化、差速贴壁结合非连续性Percoll密度梯度离心的方法获取精原干细胞;以出生后6周的雄性C57BL/6小鼠为受体,腹腔注射白消安,破坏其内源性生精功能。实验组采用曲细精管微注射法将供体精原干细胞移植入受体睾丸内,对移植后细胞进行PKH26-GL荧光追踪分析,观察其体内迁移过程,以Western Blot和RFQ-PCR法检测睾丸组织α6-Integrin,c-kit,SCF蛋白及mRNA的变化。以未接受化疗和细胞移植的正常同系生小鼠作为阳性对照组,以单侧睾丸曲细精管微注射移植细胞递质作为阴性对照组。 结果与结论：PKH26-GL荧光追踪移植细胞,移植后1周部分精原干细胞已向曲细精管基底膜迁移,移植后1个月精原干细胞已从曲细精管管腔迁移至曲细精管基底膜,并分裂增殖,移植后3个月曲细精管管腔内可见大量精子细胞形成。移植后1,2,3个月,各组α6-Integrin,c-kit蛋白表达均呈增加趋势(P < 0.01),阴性对照组、实验组SCF蛋白表达有增加趋势(P < 0.05);各组α6-Integrin,c-kit,SCF mRNA的表达均有增加趋势(P < 0.05)。提示大剂量化疗后,生精上皮内仍存在一定数量的Sertoli细胞,这种精子发生的微环境并未完全破坏,外源性精原干细胞移植后能在受体Sertoli细胞所提供的微环境中增殖和分化。     

精原干细胞和睾丸组织的同种异体移植

背景：精原干细胞作为精子发生过程的基础和前提，其自我更新和分化途径目前仍不完全清楚。 目的：观察非免疫缺陷动物新生Wistar大鼠的精原干细胞和睾丸组织移植于去势成年Wistar大鼠后的成活及生长发育情况。 设计、时间及地点：组织细胞形态学水平的随机动物对照实验，于2007-04/08在广西医科大学实验动物中心外科实验室完成。 材料：选用健康新生7~9 d雄性Wistar大鼠为供体，受体为经过严格检疫合格的8~12周的成年雄性Wistar大鼠，体质量180~220 g。 方法：取新生雄性大鼠睾丸，采用两步法组合酶顺序消化制备大鼠精原干细胞悬液，以Percoll不连续密度梯度离心法初步纯化精原干细胞。取10只成年雄性大鼠，切除双侧睾丸形成去势大鼠，按随机数字表法分为2组，每组5只。精原干细胞悬液移植组将制取好的1 mL精原干细胞悬液在5 min内注射至受体背部皮下。睾丸组织块移植组将制备好的已剖开的睾丸组织植入受体背部皮下, 每个受体移植2个睾丸4块睾丸组织。 主要观察指标：移植物的生长发育情况，移植8周末移植物的组织学特点及C-kit免疫组化定性分析结果。 结果：精原干细胞悬液移植后，移植物未见成活生长。睾丸组织块移植后移植物部分成活，移植8周末组织学检查可见特征性的精曲小管和细胞结构，可见精子细胞，部分生精小管退化；睾丸间质中可见淋巴细胞浸润；免疫组化鉴定可见睾丸组织内C-kit阳性细胞表达。 结论：同种异体异位移植于非免疫缺陷鼠中，新生睾丸组织块可以成活并能形成精子细胞，而精原干细胞悬液移植后未见移植物生长。     

维生素A对体外培养小鼠精原干细胞生长增殖的影响*

背景：维生素A在体内对精原干细胞生长具有重要作用,目前还没有发现在体外培养过程中能够很好促进精原干细胞生长与分化的诱导物质。 目的：探讨维生素A对体外培养小鼠精原干细胞生长增殖的影响。 方法：无菌收集5~7 d龄昆明雄性小鼠双侧睾丸,采用差速贴壁联合非连续性Percoll密度梯度离心法分离纯化精原干细胞。无菌取出12~15 d龄昆明雄性小鼠双侧睾丸,酶消化法分离纯化Sertoli细胞,贴壁并极化后作为饲养层,将精原干细胞接种在单层Sertoli细胞上。设立2组,实验组向DMEM/F12培养液中加入1 g/L维生素A,对照组不添加维生素A。采用酶联仪测定精原干细胞生长增殖情况,流式细胞仪检测精原干细胞生长周期。 结果与结论：共培养6,9,12,15 d时,实验组精原干细胞吸光度值明显高于对照组(P < 0.05或0.01)。随共培养时间的延长,实验组精原干细胞S期染色体含量逐渐增多,然后又逐渐下降,开始另一个分裂周期;与实验组比较,对照组精原干细胞S期染色体含量增长缓慢(P < 0.05)。小鼠精原干细胞在体外培养过程中,维生素A可促进其增殖分化。     

枸杞多糖对精原干细胞体外增殖的影响

背景：精原干细胞移植对不育具有潜在的临床应用价值,体外建立精原干细胞的培养系统获得数量较多的精原干细胞,仍是目前研究中亟待解决的问题。 目的：观察枸杞多糖对精原干细胞体外增殖的影响。 方法：采用两步酶消化法获取出生4~6 d雄性C57BL/6小鼠睾丸Sertoli细胞与精原干细胞,将精原干细胞接种在Sertoli细胞饲养层上,再加入枸杞多糖或联合细胞因子添加到细胞培养液中。1周后以流式细胞仪检测细胞周期及细胞活性率,并检测各组精原干细胞GFRa-1、Thy-1、c-kit的阳性率。 结果与结论：单独加入枸杞多糖后精原干细胞数量明显增加,增殖明显,联合加入胶质细胞源性神经营养因子与白血病抑制因子精原干细胞增殖更加明显(P < 0.05)。并发现体外培养1周后的精原干细胞仍保持其睾丸组织内的精原干细胞特征,大多仍维持在未分化状态。表明在枸杞多糖或枸杞多糖联合胶质细胞源性神经营养因子及白血病抑制因子作用下,可促进精原干细胞体外增殖。     

以α6-integrin和c-kit为特异性表面标志分离筛选小鼠精原干细胞的可行性

背景：从目前文献报道来看,精原干细胞分离效率较高且较为公认的方法是通过隐睾模型结合表面标志进行多参数筛选。 目的：探讨α6-integrin和c-kit作为分离筛选精原干细胞特异性表面标志的可行性。 设计、时间及地点：随机对照动物实验,于2006-05/12在武汉大学人民医院完成。 材料：6周龄雄性昆明白小鼠40只,随机分为隐睾组、正常对照组,20只/组。 方法：隐睾组小鼠建立隐睾模型,麻醉后腹部正中切口,将两侧睾丸拉入腹腔,将脂肪垫靠近附睾处各缝一针,分别固定在侧腹壁。正常对照组小鼠不进行任何干预。造模后两三个月,采用传统的两步消化法获取生精上皮单细胞悬液,加入FITC标记的抗α6-integrin抗体和PE标记的抗c-kit抗体,利用流式细胞仪进行α6-integrin+和c-kit-双重筛选,锥虫蓝染色监测细胞活性。 主要观察指标：隐睾的形态学变化,精原干细胞分选结果。 结果：隐睾小鼠的生精小管内细胞排列紊乱,层次及管腔消失,小管中央可见分裂相细胞,细胞数明显减少。与正常对照组比较,隐睾组side scatterlow、Forward scatterhi区的睾丸细胞增多,图形向左上移位。α6-integrin+和c-kit-细胞分布存在明显的相互偏离,即α6-integrin+细胞绝大多数不是精原干细胞,c-kit-细胞绝大多数也不是精原干细胞。从隐睾组筛选出具有side scatterlow、α6-integrin+、c-kit-特征的细胞数占睾丸细胞总数的2.8%,此即为精原干细胞,锥虫蓝监测结果显示细胞活性达95%以上。 结论：采用α6-integrin和c-kit这两种表面标志进行精原干细胞的筛选,尽管可以提高细胞悬液中的精原干细胞纯度,但均缺乏特异性。     

精子发生相关基因及凋亡基因Dazl、Pgk2、Prm2、bax在卵巢异性移植小鼠睾丸、附睾组织中的表达***☆

背景：Dazl、Pgk2、Prm2和细胞凋亡相关基因bax均参与了精子发生的调控,这些基因的表达异常和缺失常常影响精子的发生。 目的：探讨卵巢移植对异性受体精子发生相关基因表达的影响。 方法：将1 d龄小鼠卵巢移植入成年雄性受体鼠肾囊下,分激素处理或不做激素处理两个实验组;于卵巢移植后第21天观察卵巢移植体,选择卵泡发育良好的受体鼠分别采集雄鼠睾丸、附睾提取总RNA,采用半定量RT-PCR分析目的基因表达情况。对照组为未进行卵巢移植的同龄正常雄鼠。 结果与结论：各组间目的基因的表达除Prm2的相对表达量在激素处理移植组显著高于对照组外(P < 0.05),其余各组间各基因的表达差异无显著性意义(P > 0.05)。初步证实在卵巢异性移植构建雌、雄性腺同体的生理环境中,卵巢移植体对受体雄鼠几种精子发生相关基因及凋亡基因的表达无明显影响。提示卵巢移植对雄性受体小鼠的精子发生在分子水平上无明显的损害作用。     

增塑剂邻苯二甲酸二丁酯致小鼠睾丸组织的病理学改变

背景：目前国内外研究邻苯二甲酸二丁酯对生殖损害研究对象多为大鼠,且不同时间点下小鼠病理组织学未见,以小鼠为移植对象没有明确移植时间。 目的：探讨邻苯二甲酸二丁酯致小鼠睾丸组织病理学改变,并找出其改变最大的时间点,为移植做准备。 方法：妊娠balb/c小鼠20只随机分成3组,分别为正常对照组6只,玉米油对照组6只,DBP组8只。自妊娠12~21 d,分别经口给予邻苯二甲酸二丁酯和玉米油,分别在小鼠出生后4~8周每间隔1周观察仔代雄小鼠睾丸的组织病理学改变,找到变化最大的时间点。 结果与结论：邻苯二甲酸二丁酯组染毒小鼠睾丸出现明显的生理、病理和电镜下的改变。邻苯二甲酸二丁酯可引起雄性仔鼠性分化异常,睾丸生精上皮损害和生精过程障碍,从而对雄性仔鼠生育力产生不利影响,在5,6周小鼠睾丸组织损害最大,可以作为移植变化最大时间进行选择。     

金匮肾气丸对肾阳虚证雄性大鼠生精细胞中凋亡相关蛋白Bcl-2、Bax的影响**☆

背景：肾虚可导致不育,金匮肾气丸是治疗肾阳虚证的经典药物,但其作用机制尚不明确。 目的：观察金匮肾气丸对凋亡相关蛋白Bcl-2、Bax在肾阳虚证雄性大鼠生精细胞中表达的影响。 方法：成年雄性SD大鼠100只随机分成5组,采用氢化可的松注射液制备肾阳虚模型。金匮肾气丸低、中、高剂量组在造模基础上每天灌胃含生药0.625,1.250,2.500 g/kg的肾气丸混悬液,连续30 d。正常组和模型组灌胃等量蒸馏水。检测各组大鼠左侧睾丸质量、血清睾丸酮水平、精子密度、精子活率改变情况。采用免疫组织化学方法检测Bcl-2、Bax蛋白在生精细胞中的表达。 结果与结论：模型组左侧睾丸质量、血清睾丸酮水平、精子密度、精子活率低于正常组、金匮肾气丸中、高剂量组(P < 0.05)。与模型组比较,正常组、金匮肾气丸低、中、高剂量组大鼠生精细胞中Bcl-2蛋白表达显著增高(P < 0.05),Bax蛋白表达显著降低(P < 0.05)。说明金匮肾气丸可使肾阳虚证雄性大鼠生精细胞中Bcl-2蛋白表达升高,Bax蛋白表达降低,从而抑制细胞凋亡,对肾阳虚证雄性大鼠生殖能力有较好的治疗作用。     

胚胎干细胞源性肝干细胞肝内移植对宿主肝功能的影响及安全性评估**☆

背景：体外诱导胚胎干细胞分化为肝细胞已有不少成功的报道，但其体内移植后能否有效整合入宿主肝板、在肝内能否进一步生长分化并表达肝细胞功能以及成瘤的风险等情况目前还不清楚。 目的：应用治疗性肝再生模型进行胚胎干细胞源性肝干细胞肝内移植, 观察其在肝组织替代、体内的生长分化及成瘤性情况。 设计：随机对照动物实验。 单位：中山大学附属第二医院小儿外科。 材料：选用BALB/c小鼠24只为受体，鼠龄6~8周，体质量20~ 35 g，雌雄不拘购自广州市实验动物中心。实验所用胚胎干细胞源性肝干细胞由作者所在课题组诱导胚胎干细胞分化而成。小鼠胚胎干细胞株E14由本院干细胞中心提供。 方法：实验于2006-07/2007-06在中山大学附属第二医院干细胞研究中心完成。将24只小鼠随机分为2组：肝再生模型+干细胞移植组和肝切除+干细胞移植组，每组12只。前组分两次按50 mg/kg剂量腹腔内注射倒千里光碱(retrorsine) ，间隔2周，第2次注射4周后行70%肝部分切除制造肝损伤；然后经门静脉分别移植1×105羟基荧光素乙酰乙酸（CFDA-SE）荧光标记的细胞入小鼠肝内进行胚胎干细胞源性肝干细胞移植。后组在行70%肝部分切除制造肝损伤模型后进行胚胎干细胞源性肝干细胞移植。 主要观察指标：荧光显微镜下观察移植细胞组受体鼠肝脏内分布、整合与体内生长分化情况。2周后行白蛋白荧光免疫组化(双荧光染色)、血清白蛋白水平检测其功能状况。将胚胎干细胞源性肝干细胞注入治疗性肝再生小鼠肝内，将未分化的胚胎干细胞移植入小鼠腋区皮下作为对照，观察胚胎干细胞源性肝干细胞体内成瘤情况。 结果：①肝干细胞在受体鼠肝内生长情况：CFDA SE标记的胚胎干细胞源性肝干细胞肝内移植1周，受体小鼠肝实质内可见散在绿色荧光分布。2周后，肝实质内绿色荧光分布区域明显扩大，且可见类似肝索样结构排列。②肝功能：共焦白蛋白荧光免疫组化(双荧光染色)结果表明，受体小鼠肝组织内可见标记细胞表达白蛋白阳性信号（呈黄色荧光），肝再生模型+干细胞移植组和肝切除+干细胞移植组血清白蛋白水平则无明显差异（P > 0.05）。③肝干细胞移植安全性：6周内未见畸胎瘤形成，而将未分化的胚胎干细胞移植入小鼠腋区皮下6周后则可见畸胎瘤形成。 结论：胚胎干细胞源性肝干细胞移植入治疗性肝再生模型小鼠肝内后可有效在肝内能进一步生长分化并部分表达肝细胞功能；且此移植安全性较好。     

人骨髓间充质干细胞移植老年性痴呆大鼠认知能力和海马超微结构的变化

背景：因发病机制不明,目前尚无治愈老年性痴呆的有效方法。现临床上主要是采用药物治疗,而骨髓间充质干细胞的替代治疗尚处于基础研究阶段,其海马移植后对老年性痴呆认知能力的影响未见报道。 目的：探讨人骨髓间充质干细胞移植对老年性痴呆大鼠认知能力和海马超微结构的影响。 方法：老年雄性Wistar大鼠30只,制备自然衰老痴呆模型,造模后随机分为3组,选取双侧海马为移植区,分化细胞移植组注射定向神经细胞诱导分化的人骨髓间充质干细胞悬液4 μL(2×105个细胞),干细胞移植组注射等量常规培养的人骨髓间充质干细胞,模型组注射等量生理盐水。通过Y迷宫试验测定大鼠的学习、记忆能力,透射电镜观察海马区超微结构。 结果与结论：与移植前大鼠学习、记忆分数比较,移植后12周模型组均显著下降(P < 0.01),干细胞移植组均有所提高(P > 0.05),分化细胞移植组均显著提高(P < 0.01)。移植后12周与模型组比较,干细胞移植组、分化细胞移植组大鼠学习、记忆分数均显著提高(P < 0.01)。电镜观察模型组大鼠海马区神经细胞可见明显损伤,干细胞移植组损伤减轻,分化细胞移植组多数神经细胞结构正常。证实骨髓间充质干细胞移植可以提高老年性痴呆大鼠的认知能力,且定向神经诱导分化的骨髓间充质干细胞移植治疗效果优于未分化的骨髓间充质干细胞,提示骨髓间充质干细胞减少海马组织神经细胞变性坏死可能是其改善老年性痴呆大鼠认知功能障碍的作用机制之一。     

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.     

Neonatal Seizures: Problems in Diagnosis and Classification

Summary: The clinical identification of neonatal seizures is critical for the recognition of brain dysfunction; however, diagnosis is often difficult because of the poorly organized and varied nature of these behaviors. Current classification systems are limited in their ability to communicate motor, autonomic, and electroencephalo-graphic features of seizures precisely and to provide a basis for uniform effective diagnosis, therapy, and determination of prognosis. Recent investigations of neonates, utilizing bedside electroencephalographic/polygraphic/ video monitoring techniques, have provided the basis for improved diagnosis and classification of seizures in the newborn. These studies have demonstrated that not all clinical phenomena currently considered to be seizures require electrocortical epileptiform activity for their initiation or elaboration. In addition, the specific clinical character of the phenomena considered to be seizures, the clinical state of the infant, and the character of the EEG indicate the probable pathophysiological mechanisms involved and suggest probable etiologies, prognosis, and therapy. Similarities between animal models that demonstrate reflex physiology and neonates with motor automatisms and tonic posturing suggest that these clinical behaviors may not be epileptic in origin but, rather, primitive movements of progression and posture mediated by brainstem mechanisms. Although not all clinical behaviors currently considered to be neonatal seizures may have similar pathophysiological mechanisms, they are clinically significant because they all indicate brain dysfunction.     

Valproate Monotherapy in the Management of Generalized and Partial Seizures

Summary: For decades, therapeutic tradition has promoted the concept of polypharmacy in the management of epilepsy. In recent years, however, studies have shown that, for most patients, monotherapy can provide comparable or better seizure control than administration of multiple anticonvulsants, while diminishing the potential for adverse reactions, drug interactions, and poor compliance. Valproate is an important monotherapeutic agent that is highly effective in the control of idiopathic primary and secondarily generalized epilepsies, and partial seizures that do not generalize. Comparative studies have found that valproate is at least as effective as phenytoin and carbamazepine in the treatment of generalized and partial seizures. Given the similar efficacy, other factors such as pharmacokinetics and side effects may therefore determine anticonvulsant selection for monotherapy.     

Un nouveau cadre conceptuel de travail pour la psychiatrie

In an attempt to place psychiatric thinking and the training of future psychiatrists more centrally into the context of modern biology, the author outlines the beginnings of a new intellectual framework for psychiatry that derives from current biological thinking about the relationship of mind to brain. The purpose of this framework is twofold. First, it is designed to emphasize that the professional requirements for future psychiatrists will demand a greater knowledge of the structure and functioning of the brain than is currently available in most training programs. Second, it is designed to illustrate that the unique domain which psychiatry occupies within academic medicine, the analysis of the interaction between social and biological determinants of behavior, can best be studied by also having a full understanding of the biological components of behavior.