Scientia Sinica最新文献

Although there are unequivocal evidences indicating the participation of endogenous opiate-like substances in acupuncture analgesia, their exact sites of action remain to be elucidated. From the results of localization studies by injecting minute amount of narcotic antagonist naloxone into discrete brain areas and assessing its effect on acupuncture analgesia in rabbits it is concluded that nuclei accumbens, amygdala, habenula and periaquaductal grey are the strategic sites for endogenous opioids to exert their analgesic effect. These brain areas are also of extreme importance for the realization of morphine analgesia.

During the process of reconstitution of pig heart mitochondrial H+-ATPase on liposomes by cholate dialysis method, 1 mM Mg2+ in the dialysis medium can obviously increase activities of the reconstituted H+-ATPase (32Pi-ATP exchange, enzyme activity and its sensitivity to oligomycin or DCCD and ATP-dependent ANS 1) fluorescence). Besides Mg2+, effects of other divalent cations and spermidine on the H+-ATPase reconstitution have been compared. The effectiveness of the divalent cation activation of 32Pi-ATP exchange of the reconstituted H+-ATPase, decreased in the order: Mg2+ greater than Ca2+ greater than Mn2+ greater than Sr2+, while that of increasing the sensitivity to the inhibitors: Ca2+ greater than Mg2+ greater than Mn2+ greater than Sr2+. No significant effect on the H+-ATPase reconstitution has been found with Cd2+, Zn2+ and spermidine3+. Mechanism of action of the divalent cations on reconstitution has been discussed.

Two biologically active peptides designated SCP-1 and SCP-2 have been isolated and partially characterized from porcine spinal cord. The results of amino acid analysis, electrophoresis, isoelectric focusing and the chromatographic analysis of the dansylated derivatives indicate that these two peptides are homogeneous. The amino acid composition and apparent untriakontapeptide and SCP-2 is a pentacospeptide. The N-terminal amino acids of SCP-1 and SCP-2 are Arginine and Tryptophan respectively. SCP-1 can stimulate the contraction of isolated guinea pig ileum and SCP-2 induces hypotension in anesthetized rat. Both SCP-1 and SCP-2 show no morphine-like activity. The chemical composition and biological properties of SCP-1 and SCP-2 distinguish them from any known peptide.

The results of competitive bending experiment and the electron-microscopic autoradiographic studies show that the peptide hormone, LH-RH-A (a nonapeptide), could be internalized into the gonadotrophs of the pituitary gland of the mud-carp (Cirrhrinus molitorella). It is demonstrated that the labeled peptide, 125I-LH-RH-A, is internalized not only into the cytoplasm, but also into the nucleus, apparently via the nuclear pores. It is, therefore, suggested that the peptide hormone might act directly on the genome either in the form of a hormone-receptor complex or of a single molecule.

Under low background illumination, the pupil responds only to an increase in light intensity by a transient constriction when the extent and rate of the increase exceed a certain values. We term this response the dynamic papillary response in order to differentiate it from the much more sluggish and much less pronounced response moiety that governs the static pupil size according to the level of light adaptation. The characteristics of the dynamic response are studied in some detail. This virtually unidirectional rate sensitivity of pupil to light renders it difficult to be subjected to frequency-response analysis even by small signal approximation. Analysis of the experimental results suggests that this transient response is a light-precipitated confluence of few consecutive hippus.

In the present paper, the synthesis and analgesic activity (mice, i.p. hot plate test) of the derivatives of 3-methyl fentanyl are briefly described. Compound 7302, cis-N-[1-(2-hydroxy-2-phenylethyl)-3-methyl-4-piperidyl]-N-phenylpropionamide (cis: 3-methyl/4-N-phenylpropionamide) is found to be the most potent analgesic agent in this series synthesized by our laboratory (ED50 = 0.0022 mg/kg). The analgesic activity of 7302 is 28 times more potent than that of fentanyl and 6300 times more than that of morphine. The partition coefficients of 10 compounds in the series are determined by high performance liquid chromatography (HPLC) and their log p values are about 3. There are no regular relationships between the analgesic activity and partition coefficients. Study on the specific binding of 8 out of the above 10 compounds to crude synaptic plasma membrane (P2-fraction) of mouse brain demonstrates that there is an excellent statistical linear correlation (r = 0.998) between the analgesic potency and the specific binding affinity. The result shows that the analgesic potency of the derivatives of this series is mainly dependent on binding affinity for opiate receptor.

With the slow muscle fibres in the pure slow muscle ALD as well as in two mixed muscles, flexor metacarpi ulnaris and sartorius, it is demonstrated that the phenomenon of postdenervation hypertrophy still occurs under conditions preventing stretch of muscle after denervation or even in tenotomized muscles in shortened state relieved of tension. Striking differences between the slow fibres of the ALD and those of the mixed muscles are seen, both with respect to their histochemical property and to the degree of development of post-denervation hypertrophy. The slow fibres in the mixed muscles show the phenomenon of post-denervation hypertrophy in a much more striking form than the ALD fibres and should be made more use of in further studies on the phenomenon.

The results of the present study have shown no change in the activity of ATPase of the renal cortex of rats administered gossypol for half a year. The Na+, K+-ATPase activity of the cellular membrane of renal cortex of guinea pigs fed with gossypol for 5 or 9 weeks is significantly altered. It seems possible to diminish or to delay the inhibition by allowing the guinea pigs a potassium-rich diet ad libitum. In vitro, gossypol inhibits significantly the activity of ATPase of the brain and the kidney of rats and guinea pigs uncompetitively. However, the inhibition of the ATPase of human fetus kidney is of a mixed type.

This paper deals with a well-preserved human cranium of late Middle Pleistocene, belonging to a young male individual. It has many characters identical to those of early Homo sapiens or intermediate between Homo erectus and modern man. It possesses also some features similar to those of modern man, and close to Homo erectus in some respects. So it probably belongs to an archaic type to early Homo sapiens. Taken with other Chinese human fossils it is on the continuous human evolutionary line in China. The cranium differs from Neanderthals in a number of racial characteristics. It is therefore considered here a new subspecies: Homo sapiens daliensis.