Genetic linkage studies suggest that Alzheimer's disease is not a single homogeneous disorder. FAD Collaborative Study Group

Alzheimer's disease, a fatal neurodegenerative disorder of unknown aetiology, is usually considered to be a single disorder because of the general uniformity of the disease phenotype. Two recent genetic linkage studies revealed co-segregation of familial Alzheimer disease with the D21S1/S11 and D21S16 loci on chromosome 21. But two other studies, one of predominantly multiplex kindreds with a late age-of-onset, the other of a cadre of kindreds with a unique Volga German ethnic origin, found absence of linkage at least to D21S1/S11. So far it has not been possible to discern whether these conflicting reports reflect aetiological heterogeneity, differences in methods of pedigree selection, effects of confounding variables in the analysis (for example, diagnostic errors, assortative matings), or true non-replication. To resolve this issue, we have now examined the inheritance of five polymorphic DNA markers from the proximal long arm of chromosome 21 in a large unselected series of pedigrees with familial Alzheimer's disease. Our data suggest that Alzheimer's disease is not a single entity, but rather results from genetic defects on chromosome 21 and from other genetic or nongenetic factors.     

Co-localization of GABA receptors and benzodiazepine receptors in the brain shown by monoclonal antibodies

The most abundant inhibitory neurotransmitter in the central nervous system, gamma-aminobutyric acid (GABA), exerts its main effects via a GABAA receptor that gates a chloride channel in the subsynaptic membrane. These receptors can contain a modulatory unit, the benzodiazepine receptor, through which ligands of different chemical classes can increase or decrease GABAA receptor function. We have now visualized a GABAA receptor in mammalian brain using monoclonal antibodies. The protein complex recognized by the antibodies contained high- and low-affinity binding sites for GABA as well as binding sites for benzodiazepines, indicative of a GABAA receptor functionally associated with benzodiazepine receptors. As the pattern of brain immunoreactivity corresponds to the autoradiographical distribution of benzodiazepine binding sites, most benzodiazepine receptors seem to be part of GABAA receptors. Two constituent proteins were identified immunologically. Because the monoclonal antibodies cross-react with human brain, they provide a means for elucidating those CNS disorders which may be linked to a dysfunction of a GABAA receptor.     

重型钎杆用钢40SiMnCrMoV

在H_2O和5％NaCl水溶液中以浸泡试验用腐蚀增重和腐蚀失重法测量,并结合机械性能进行分析,可以认为40SiMnCrMoV钢完全可以代替40SiMnMoV和40CrNi3Mo钢制做重型钎杆。     

流体浓缩试验研究

流体食品常常局部地脱水以减少水的含量．增加贮藏的稳定性．蒸发是流体浓缩景广泛应用的一种方法本文描述浓缩的一种新颖系统，该系统在减压的情况下，水蒸气从流体食品中蒸发而使其浓缩本试验是在设计的单效降膜式蒸发器上进行的．研究了流体浓缩速度，流体食品流速，流体食品浓缩及流体食品温度对蒸发速度的影响，并讨论了实验结果．     

Structural parts involved in activation and inactivation of the sodium channel

Structure-function relationships of the sodium channel expressed in Xenopus oocytes have been investigated by the combined use of site-directed mutagenesis and patch-clamp recording. This study provides evidence that the positive charges in segment S4 are involved in the voltage-sensing mechanism for activation of the channel and that the region between repeats III and IV is important for its inactivation.     

Dimethyltryptamin: Its metabolism in man; the relation of its psychotic effect to the serotonin metabolism

Zusammenfassung Es wird festgestellt, dass Dimethyltryptamin — bei normalen Versuchspersonen — eine dem Meskalin und dem LSD-25 ähnliche psychotische Wirkung hat. Der durch Dimethyltryptamin induzierte Zustand beginnt schon 3–5 min nach Injektion und verschwindet bereits nach 1 h. Der Urin der Versuchspersonen wurde papier-chromatographisch und kolorimetrisch auf Indolverbindungen geprüft. 3-Indolylessigsäure wird als hauptsächlichstes Abbauprodukt des Dimethyltryptamins gefunden, wovon der grösste Teil in alkali-labiler Form gebunden ist. Die Menge der ausgeschiedenen 5-Hydroxy-indolylessigsäure ist nach dem Versuch wesentlich grösser als vorher. Die Stoffwechselzusammenhänge mit dem psychotischen Zustand werden diskutiert.     

A simple system of multiple organ-baths

Summary A compact and easily assembled system of multiple organ-baths is described, in which use is made of readily available materials.Acknowledgment. G.E.R. was in receipt of the ruggles Gates Research Award.     

The organic acid-soluble phosphate contents of mammalian and avian erythrocytes at the beginning of postnatal life

Zusammenfassung Die bisherigen Angaben eines reichen organischen säurelöslichen Phosphatgehalts der Erythrozyten können für junge Tiere nicht verallgemeinert werden.Bei zahlreichen Säugerarten zeigen die Erythrocyten der Neugeborenen infolge einer sehr niedrigen Konzentration von Phosphoglycerinsäure einen Gehalt an organischem, säurelöslichem Phosphat, der unter demjenigen des ausgewachsenen Tieres liegt.Wir stellen weiterhin fest, dass die bedeutenden Spezies-Unterschiede der Adulttiere in frühen Ontogenesephasen kaum hervortreten.