In a study of the functional organization of the cholinergic synapse using the electromotor system of the electric ray, Torpedo marmorata, two main pools of transmitter have been identified: The cytoplasmic, comprising about 20% of terminal acetylcholine, and the vesicular. The latter is morphologically and metabolically heterogeneous. In resting tissue, about 15% of the vesicles have a relatively low transmitter content and density; they are immature (V₀) vesicles newly arrived from the cell body by axonal transport. Approximately 35% of vesicles belong to the recycling (V₂) pool; these are denser than the main population due to osmotic dehydration attendant upon a reduced osmotic load. The majority (50%) are fully charged ‘reserve’ (V₁) vesicles. On perfusion, when axonal replenishment and impulse traffic are alike cut off, V₀ and V₂ vesicles take up more transmitter and join the V₁ pool which now comprises over 90% of all vesicles. On stimulation the V₂ population is greatly increased at the expense of V₁, but in an ensuing period of rest rejoins the V₁ population. Work with isotopically labelled transmitter precursors, false transmitters and endocytotic markers shows that the V₂ population is the origin of quantized release. The cytoplasmic pool, however, is also functionally important since it the site of transmitter synthesis for vesicular uptake and is subject to ‘futile recycling’ brought about by the continuous molecular leakage of transmitter into the extracellular space, its hydrolysis by acetylcholinesterase, the uptake of choline and acetate and their resynthesis to acetylcholine. This indicates a control or regulatory function. There is little exchange between this pool and fully changed V₁ vesicles but it supplies the recycling vesicles of the V₂ pool with transmitter. In this way, quantal size is kept constant and largely independent of cytoplasmic transmitter concentration. In recent years considerable progress has been made in understanding the organization of the cholinergic synapse, largely by intensive work on one particular model system: the electromotor synapses of the electric rays Torpedo marmorata and T. californica. Methods have been devised for isolating functional nerve terminals (synaptosomes), presynaptic plasma membranes, synaptic vesicles and vesiculated fragments (microsacs) of the postsynaptic membrane. From the cell bodies of the electromotor neurones, mRNAs have been isolated that code for presynaptic proteins, and from the target cells (the electrocytes), mRNAs coding for polypeptides comprising or accompanying the receptor. From the latter, using the cDNA technique, Numa and colleagues have deduced the structure of the receptor in great detail. The present lecture will concentrate on the functional organization of the presynaptic nerve terminals.

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For successful performance of phonosurgery, it is most important to maintain the flexibility of the vocal fold. Unfortunately, however, there has been no direct effective method so far for assessing the flexibility of the vocal fold membrane. If the vocal fold surface showed any abnormal region where good vibration could not be observed, reduced flexibility was expected in this area. Hitherto, for observation of the vocal fold vibration, a laryngostroboscope has been in use clinically. However, the laryngostroboscope can not be applied effectively when the patient is unable to phonate for reasons such as under general anesthesia with tracheal tube or when his/her voice is too hoarse to drive a laryngostroboscope well. Instead of observing phonatory vibrations, Fukuda designed a new vibratory method that makes it possible to externally induce wavelike motion on the surface of the vocal fold even under aforementioned unfavorable conditions. In this study, by using the new method, it was possible to observe externally induced vibration on the normal membrane surrounding the abnormal region with mass as well as in the abnormal region itself such as in polyp, cyst, or polypoid degeneration. We were also able to examine whether the abnormal regions with mass would have any effect on the vocal fold. As result, by this method of externally inducing vibration, we were able to detect the mucous membrane lined cavities of the polyp on the surface. The mass had hardly any effect on the normal region.

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Porous and granular hydroxylapatite (HAP) was implanted in bone defects resulting from oral surgery in 21 patients and from periodontal disease in 14 patients. Excellent results were obtained, the overall clinical usefulness being 91.4%. HAP leakage after implantation was observed in a small number of cases; however, there was almost no wound infection or failure to heal. A series of x-rays confirmed its good adaptation to the bone.

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Chondrocytes from Swarm rat chondrosarcoma were successfully maintained in a suspension culture for over 18 months without losing its original phenotypic traits of producing tumor upon transplantation and of synthesizing cartilage-type proteoglycans. The chondrocytes were initially cultured by using a cell-encapsulation technique with alginate gels and were grown in an ordinary Dullbecco's modified Eagle's medium containing fetal bovine serum. The cells thus obtained after 18 months were morphologically indistinguishable from the chondrocytes in situ in the orginal tumor. No fibroblast-like cell was detected in the cultured cell population. When transplanted into rats, they grew at a rate comparable to that of original chondrosarcoma cells. This observation was supported, thought not directly, by measuring the rate of ³H-thymidine incorporation into their DNA fractions, which was also comparable to that of the original tumor cells. Biochemically, the cultured cells were able to synthesize proteoglycans at a similar rate to that by freshly isolated cells from the tumor. The molecular size and subclass of the proteoglycans produced within the cells or secreted to the extracellular medium were the same as those produced by the chondrosarcoma tumor cells and also to those synthesized by normal cartilage. Thus, the present culture system can be used as a suitable model to study the synthesis and assembly of the extracellular matrix in connective tissues, especially, those in cartilage.

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A recurrent spontaneous complete remission of acute hypoplastic leukemia was observed. The remission occurred after a severe infection which was treated with antibiotics. Reports of spontaneous remission of acute leukemia in adults have become increasingly rare, and the remissions themselves are short-lived. Such spontaneous complete remissions are almost always associated with bacterial infections and blood transfusions. Previous cases are summarized, and the pathophysiologic factors are discussed.

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Jugular wave recognition requires looking for descents rather than rises. The dominant normal descent is systolic and should be called the X prime (X') descent. The X' is a rapid collapse caused by the descent of the base of the right ventricle and can be easily recognized by noting that the collapse falls onto the second heart sound or is simultaneous with the radial pulse. The V wave and Y descent is expected to be easily visible only in the young. The C wave is never visible. It is difficult to learn jugular recognition from most textbooks mainly because they use the letter X for both the atrial relaxation descent and the descent of the base descent and also, they teach from artifactual pulse tracings and they recommend looking for waves rather than descents.

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The discussion will examine the brain-barrier system primarily in regard to the movements of amino acids, since these substances have been investigated at greater detail than any others. In addition to the blood-brain barrier, that is, capillary transport, other membrane transport systems, neuronal, glial, and synaptosomal, will be examined, and differences among them will be discussed. Amino acid exit and passive diffusion will also be discussed. The major questions concern the functions of the barriers and of the multiple transport systems in the different structural elements. The relationship of amino acid precursor levels to neurotransmitter synthesis and dietary influences on cerebral amino acid pools have been established. Little is known about the influence of amino acids on protein metabolism. The fact that the levels of cerebral amino acids show regional heterogeneity, and change under a number of conditions, for example, during development, facilitates examination of the factors determining substrate levels and distribution. Although many aspects of substrate transport levels and distribution. Although many aspects of substrate transport are not unique for the nervous system, a number of systems are found only in the brain and have specific functions different from those of the rest of the organism, and their sensitivity to pharmacological and pathological influences makes the transport and barrier systems of special interest to neurobiologists.

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