羟基磷灰石/胶原蛋白复合支架上骨髓间充质干细胞的增殖与分化

摘要 背景：最近胶原蛋白作为细胞体外三维立体支架材料被大量用于组织工程,但胶原蛋白支架材料机械强度低,很难承受较大外力,为此将胶原蛋白与羟基磷灰石制成复合支架材料,探索复合支架的生物相容性和生物活性。 目的：验证大鼠骨髓间充质干细胞在羟基磷灰石/胶原蛋白复合支架上的增殖与分化情况。 方法：贴壁法分离SD大鼠骨髓间充质干细胞,分别在平板、胶原支架、羟基磷灰石/胶原蛋白复合支架上,观察3种条件下细胞的生长状况,四甲基偶氮唑盐法检测其增殖情况。培养14,21 d后,考察细胞碱性磷酸酶活性及胶原蛋白分泌量。 结果与结论：发现骨髓间充质干细胞在羟基磷灰石/胶原蛋白复合支架上铺展良好,其增殖率显著高于纯胶原蛋白支架上培养的细胞,并高于平板培养细胞。骨髓间充质干细胞在羟基磷灰石/胶原蛋白复合支架上的碱性磷酸酶活性及胶原蛋白分泌量明显高于纯胶原蛋白支架,高于平板培养。结果提示,羟基磷灰石/胶原蛋白复合材料能促进骨髓间充质干细胞的增殖和分化,并诱导骨髓间充质干细胞向成骨细胞分化。 关键词：胶原蛋白;羟基磷灰石;骨组织工程;骨髓间充质干细胞;支架 doi:10.3969/j.issn.1673-8225.2010.47.014     

纳米羟基磷灰石/壳聚糖复合材料与兔骨髓间充质干细胞的生物相容性

背景：清华大学材料科学与工程系冯庆玲教授等采用仿生学原理,制成一种塑形简便并且具有良好骨传导、骨诱导性的纳米羟基磷灰石/壳聚糖复合骨修复材料。但制备的复合材料是否仍具良好的生物相容性尚不确切。 目的：观察纳米羟基磷灰石/壳聚糖复合材料与兔骨髓间充质干细胞的相容性。 设计、时间及地点：体外观察实验,于2008-08/11在南方医科大学珠江医院中心实验室完成。 材料：纳米羟基磷灰石/壳聚糖复合材料由清华大学材料系研制,孔隙率90%,孔径50~200 μm。骨髓间充质干细胞由2周龄健康新西兰大白兔股骨和胫骨骨髓经密度梯度离心法获得。 方法：将预湿后的纳米羟基磷灰石/壳聚糖材料置于培养板内,将第3代骨髓间充质干细胞接种于材料表面在体外复合培养。对照组为单纯骨髓间充质干细胞培养。 主要观察指标：倒置显微镜、扫描电镜观察细胞和材料复合培养后细胞生长状况,计数细胞接种后1,2,4 h在材料表面的黏附状况,CCK-8检测细胞在复合材料上的增殖状况,流式细胞仪检测种植细胞的细胞周期。 结果：骨髓间充质干细胞在复合材料表面上生长状况良好。细胞接种到复合材料1 h时黏附率低于对照组（P < 0.05）,但接种2,4 h后两组黏附率差异无显著性意义（P > 0.05）。细胞接种后,两组均保持正常的分裂增殖速度(P > 0.05) 。材料组和对照组细胞皆为正常的二倍体细胞,未见异倍体细胞形成,复合材料对兔骨髓间充质细胞的细胞周期影响不大。 结论：纳米羟基磷灰石/壳聚糖与骨髓间充质干细胞具有良好的生物相容性。     

仿生支架材料骨形态发生蛋白7多肽/壳聚糖/纳米羟基磷灰石/胶原的制备及其细胞相容性

摘要 背景：目前骨组织工程常用的支架材料主要有无机材料、有机高分子材料及天然衍生材料等，上述材料各有优缺点，为了充分发挥各类材料的优势，弥补其不足，目前多采用联合材料制备复合支架。 目的：制备新型仿生支架材料骨形态发生蛋白7多肽/壳聚糖/纳米羟基磷灰石/胶原，并观察其对骨髓间充质干细胞增殖、黏附及分化的影响。 方法：制备壳聚糖/纳米羟基磷灰石/胶原复合支架材料，扫描电镜观察支架材料表面微观形貌；采用真空吸附法将骨形态发生蛋白7多肽与支架材料复合，高效液相色谱仪检测骨形态发生蛋白7多肽在体外的释放规律；将骨髓间充质干细胞接种到复合骨形态发生蛋白7多肽的仿生支架材料上，以未复合多肽的支架材料作为对照，检测支架材料表面细胞增殖、黏附率、生长形态及碱性磷酸酶活性。 结果与结论：壳聚糖/纳米羟基磷灰石/胶原支架材料呈多孔状，孔径10~100 µm；骨形态发生蛋白7多肽可以从支架材料中缓慢释出；在复合多肽的仿生支架材料表面，骨髓间充质干细胞的黏附及向成骨细胞方向分化能力均明显强于对照组(P < 0.05)，而增殖能力与对照组差异无显著性意义(P > 0.05)。说明新型仿生支架材料骨形态发生蛋白7多肽/壳聚糖/纳米羟基磷灰石/胶原是一种理想的骨组织工程支架材料，具有良好的细胞相容性。 关键词：支架材料；骨形态发生蛋白7多肽；壳聚糖；胶原；纳米羟基磷灰石；骨组织工程；细胞相容性 doi:10.3969/j.issn.1673-8225.2011.08.014     

多孔碳酸钙陶瓷与干细胞源性成骨细胞的相容性

背景：国内外的研究证实普通碳酸钙陶瓷作为骨替代材料时具有细胞支架作用。 目的：观察多孔碳酸钙陶瓷与成骨细胞的相容性,及作为骨组织工程支架的可能性。 方法：SD大鼠骨髓基质干细胞经矿化诱导培养、扩增并检测证实其已具成骨细胞表型后,分别与多孔碳酸钙陶瓷支架、普通羟基磷灰石陶瓷支架体外复合培养。 结果与结论：骨髓基质干细胞经体外诱导形成成骨细胞,钙结节、Ⅰ型胶原和碱性磷酸酶免疫染色结果阳性。多孔碳酸钙陶瓷支架材料与羟基磷灰石陶瓷材料皆有细胞附着生长,但多孔碳酸钙陶瓷支架材料细胞的黏附能力、增殖活力及成骨活性均强于羟基磷灰石陶瓷材料。提示多孔碳酸钙陶瓷支架材料与SD大鼠骨髓基质干细胞源性成骨细胞有良好相容性。     

纳米晶羟基磷灰石胶原复合骨髓间充质干细胞修复骨缺损

背景：临床上对大范围骨缺损还没有很有效的治疗手段，而纳米晶羟基磷灰石胶原复合材料与天然骨骼的结构类似，具有较好的生物相容性，可能为修复骨缺损提供新的途径。 目的：观察纳米晶羟基磷灰石胶原材料复合骨髓间充质干细胞在修复骨缺损中的作用。 方法：分离培养人骨髓间充质干细胞，与纳米晶羟基磷灰石胶原材料于体外联合培养；通过大体观察、组织学分析及电镜观察了解成骨情况，进一步临床应用于修复骨缺损。 结果与结论：人骨髓间充质干细胞在体外可以大量扩增，复合细胞的材料植入骨缺损处后，X射线摄片动态观察可见骨缺损处连接良好。说明骨髓间充质干细胞具有成骨细胞作用，纳米晶羟基磷灰石胶原材料是一种很好的构建组织工程骨的支架材料。 关键词：骨髓间充质干细胞；羟基磷灰石；纳米材料；组织工程；骨     

纳米羟基磷灰石/壳聚糖支架与诱导骨髓间充质干细胞体外构建软骨支架复合体

背景：国内外许多研究通过不同的构建方法构建组织工程化软骨支架复合体修复骨软骨联合缺损,且取得了一定的进展,但目前各种方法存在的问题突出表现为组织工程化的软骨和骨组织之间的界面、移植体和宿主骨和软骨之间的界面耦合不够理想。 目的：将体外提纯、扩增的骨髓间充质干细胞诱导成软骨细胞,将其接种于穿“靴”的纳米羟基磷灰石/壳聚糖支架的底部上联合培养,探索其用于组织工程软骨复合体的可行性。 设计、时间及地点：细胞和材料复合的体外观察实验,于2008-03/07在暨南大学附属第一医院中心实验室和暨南大学理工学院材料系实验室完成。 材料：通过原位复合和冷冻干燥结合的方法制备纳米羟基磷灰石/壳聚糖支架。健康新西兰兔10只由广东省医学实验动物中心提供。 方法：密度梯度离心法提取分离骨髓间充质干细胞,软骨诱导液诱导骨髓间充质干细胞2周后甲苯胺蓝染色检测。把诱导得到的软骨细胞接种于穿“靴”的纳米羟基磷灰石/壳聚糖支架的底部,将细胞-支架复合物置入成软骨条件培养液中培养2周。 主要观察指标：倒置相差显微镜下观察细胞形态特征,鉴定CD29,CD44,CD34和CD45抗原的表达,观察细胞生长特性,测定细胞活力和生长周期,扫描电镜观察纳米羟基磷灰石/壳聚糖支架结构和细胞与支架的复合情况。 结果：骨髓间充质干细胞可在体外分离扩增,表达CD29和CD44,不表达CD34和CD45,细胞活力为95.27%,G0~G1期细胞占94.68%。经软骨诱导液诱导后骨髓间充质干细胞转化成软骨细胞;制备的纳米羟基磷灰石/壳聚糖多孔支架孔隙率为90%,平均孔径为150 μｍ,与软骨细胞有较好的黏附性。 结论：初步证实纳米羟基磷灰石/壳聚糖支架与骨髓间充质干细胞诱导成的软骨细胞复合可以在体外构建组织工程软骨复合体。     

纳米晶羟基磷灰石/胶原骨与骨髓间充质干细胞的相容性

背景：组织工程支架材料表面的微观和亚微观结构对细胞的黏附与生长有很重要的影响。利用纳米技术和三维造孔技术制备的纳米晶羟基磷灰石/胶原骨模仿了天然骨的成分与微结构特征。 目的：观察体外培养的人骨髓间充质干细胞与纳米晶羟基磷灰石/胶原骨的细胞相容性。 设计、时间及地点：单一样本观察，于2005-09/2006-12在江苏大学医学技术学院完成。 材料：纳米晶羟基磷灰石/胶原骨由清华大学材料科学与工程系研制。人骨髓间充质干细胞由健康成年志愿者自愿捐献，受试者对实验内容知情同意。 方法：全骨髓法体外培养骨髓间充质干细胞，应用成骨诱导剂（地塞米松、维生素C、β-磷酸甘油、碱性成纤维细胞生长因子）诱导向成骨细胞表型转化。将第3代骨髓间充质干细胞与纳米晶羟基磷灰石/胶原骨复合培养14 d。 主要观察指标：通过碱性磷酸酶组织化学染色、Von Kossa染色鉴定诱导培养的成骨细胞的细胞学特性。通过倒置显微镜、扫描电镜观察细胞生长及其在纳米晶羟基磷灰石/胶原骨上的生长情况。 结果：原代培养的骨髓细胞增殖迅速，10~ 12 d左右即可稳定传代，传代细胞7~9 d即可传代。经诱导培养的细胞碱性磷酸酶组织化学染色阳性，Von Kossa染色阳性，可见钙化的基质沉积，呈现典型的成骨细胞形态和生物学特征。构建的骨髓间充质干细胞与纳米晶羟基磷灰石/胶原骨共培养模型中，细胞可在纳米晶羟基磷灰石/胶原骨表面良好贴壁。复合培养8 d,分布于支架材料上的细胞大量增殖、分泌细胞外基质。复合培养14 d，大量细胞在材料表面和孔隙中生长，细胞之间广泛存在突起连接。 结论：纳米晶羟基磷灰石/胶原骨适合种子细胞的贴附、生长和增殖，细胞相容性良好。     

纳米晶胶原基骨修复材料与兔骨髓间充质干细胞体外复合培养*

背景：纳米晶羟基磷灰石胶原基骨修复材料具有与天然骨成分接近,结构和形貌图谱分析与天然骨相似,生物相容性好等特点,且材料多孔,孔径较大、孔隙率及孔隙交通率高,符合作为骨组织工程支架材料的要求。 目的：观察兔骨髓间充质干细胞与纳米晶胶原基骨修复材料体外复合培养的结合程度。 设计、时间及地点：体外观察实验,于2006-03/09在江苏大学医学院细胞实验室完成。 材料：健康雄性新西兰大白兔1只,1月龄。纳米晶胶原基骨修复材料由清华大学材料系提供。 方法：体外分离培养、纯化兔骨髓间充质干细胞,取第3代骨髓间充质干细胞与纳米晶胶原基骨体外复合培养。 主要观察指标：①兔骨髓间充质干细胞生长形态及生长曲线。②复合培养5,10 d后扫描电镜观察二者复合程度。③复合培养5,10 d时纳米晶胶原基骨修复材料上结合的细胞数量。 结果：兔骨髓间充质干细胞贴壁生长,增殖速度快,生长曲线符合Logistic生长曲线,兔骨髓间充质干细胞与纳米晶胶原基骨体外复合培养,在第5,10天进行扫描电镜观察,发现10 d时黏附于纳米晶胶原基骨上的骨髓间充质干细胞数明显高于5 d时黏附的细胞数,差异有显著性意义(P < 0.01)。 结论：兔骨髓间充质干细胞与纳米晶胶原基骨体外复合培养结合程度较高。     

丝素蛋白/羟基磷灰石材料复合骨髓间充质干细胞构建组织工程化软骨

背景：随着组织工程的兴起,软骨损伤的修复可能性显著地提高,但单一的支架材料均不能符合理想支架,有一定的局限性。 目的：观察骨髓间充质干细胞复合丝素蛋白/羟基磷灰石构建组织工程化软骨的可行性。 方法：体外分离培养骨髓间充质干细胞,并定向诱导成软骨细胞,与丝素蛋白/羟基磷灰石复合培养,构建膝关节胫骨平台全层关节软骨缺损。54只大白兔单侧膝关节全层软骨缺损模型后随机抽签法分为3组,复合组植入细胞-丝素蛋白/羟基磷灰石复合物;材料组植入单纯丝素蛋白/羟基磷灰石,对照组不行任何植入。植入后8,12周CT检查及组织学检查观察软骨缺损修复情况。 结果与结论：植入后8周,复合组关节面不平整,关节间隙增大,形成新生类软骨细胞,基质丰富。材料组关节面塌陷,软骨细胞少量增殖。植入后12周,复合组关节面平整,关节间隙如常。大量软骨细胞出现,与周边软骨色泽一样,支架材料完全降解。材料组关节面不平整,软骨细胞不完全充填,支架材料部分降解。对照组未见修复。提示用骨髓间充质干细胞复合丝素蛋白/羟基磷灰石可形成透明软骨修复动物膝关节全层软骨缺损,显示了丝素蛋白/羟基磷灰石材料作为关节软骨组织工程支架材料的良好生物相容性。     

可注射性纳米羟基磷灰石/壳聚糖复合骨髓间充质干细胞促进骨缺损的修复

背景：可注射性纳米羟基磷灰石/壳聚糖复合材料是清华大学利用仿生学原理制备的一种较理想的组织工程新型材料,经过前期体外实验证明其具有良好的生物相容性和骨传导性。 目的：观察骨髓间充质干细胞复合可注射性纳米羟基磷灰石/壳聚糖材料在促进骨缺损修复中的作用。 方法：用梯度离心和贴壁培养法收集兔骨髓间充质干细胞,分离、培养至第3代,然后与纳米羟基磷灰石/壳聚糖复合。24只新西兰大白兔双侧股骨外侧髁钻孔,制备骨缺损模型。所有兔右侧股骨外侧髁缺损以骨髓间充质干细胞-纳米羟基磷灰石/壳聚糖局部植入作为实验组,其中20只兔左侧股骨外侧髁缺损以单纯纳米羟基磷灰石植入治疗作为对照组,4只兔左侧股骨外侧髁缺损旷置为空白组,于第12周末,分别行大体、影像学观察、组织形态学、观察该复合材料对兔骨缺损的修复效果。 结果与结论：术后12周实验组植入体已与骨缺损处骨性愈合,明显见新生骨生成,骨缺损能够完全修复,对照组骨缺损处部分修复,部分骨皮质不连续。空白组缺损区尚未见修复,纤维结缔组织填充。术后12周,实验组见骨形成细胞较多,材料内见新生骨小梁相互连接成片;对照组少量骨细胞形成,骨量少,部分纤维组织填充。空白组未见骨形成细胞,纤维组织较多。结果表明,骨髓间充质干细胞-纳米羟基磷灰石/壳聚糖复合材料具有骨缺损修复能力,其疗效优于单纯纳米羟基磷灰石材料。 关键词：纳米羟基磷灰石/壳聚糖;骨髓间充质干细胞;骨缺损;兔;可注射 doi:10.3969/j.issn.1673-8225.2010.34.003     

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.     

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.     

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.     

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.     

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.     

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.