[Experimental study of Chinese Agkistrodon acutus venom in activation of rabbit platelets in vivo]

Fourteen Albino rabbits, male and female, were allocated randomly into two groups: control group which had intravenous infusion of normal saline, and experimental group which had intravenous infusion of Chinese Agkistrodon Acutus venom (CAAV) 0.075 mg/kg. Platelet was reduced, plasma PF4 activity and 5-HT concentration increased, 5-HT content in platelets was reduced in the experimental group 10, 20, and 50 minutes after the infusion. It had a significant difference (P < 0.01), compared with that in the control group. Platelets were aggregated into masses under electron microscope 10 minutes after the infusion of CAAV. The study has proved that blood platelets in rabbits are activated by Chinese Agkistrodon Acutus venom.

Convergence of somatic and visual afferent impulses in the Wulst of pigeon

In 79 pigeons, unit discharges of Wulst neurons responding to bilateral stimulation of N. radialis and N. sciaticus and to bilateral light flashes were recorded. Of 178 such neurons, 55 showed multisensory convergence of various types: 40 of these were somatic convergent neurons, characterized as 3 types; three were binocular convergent cells; and twelve were bimodal (visual-somatosensory) convergent neurons. Of these neurons, the convergent action was either inhibitory or excitatory. These results suggest that the Wulst may function as an important centre for integrating visual and somatic sensory information.

Location of crossovers during gene targeting with insertion and replacement vectors

Gene targeting was used to introduce nonselectable genetic changes into chromosomal loci in mouse embryo-derived stem cells. The nonselectable markers were linked to a selectable marker in both insertion- and replacement-type vectors, and the transfer of the two elements to the Hprt locus was assayed. When insertion vectors were used as substrates, the frequency of transfer was highly dependent upon the distance between the nonselectable marker and the double-strand break in the vector. A marker located close to the vector ends was frequently lost, suggesting that a double-strand gap repair activity is involved in vector integration. When replacement vectors were used, cotransfer of a selectable marker and a nonselectable marker 3 kb apart was over 50%, suggesting that recombination between vector and target often occurs near the ends of the vector. To illustrate the use of replacement vectors to transfer specific mutations to the genome, we describe targeting of the delta F508 mutation to the CFTR gene in mouse embryo-derived stem cells.

[A report on investigation of an outbreak of Legionnaires' disease in a hotel in Beijing]

During the period from February to March, 1992, an outbreak of upper respiratory infection (influenza-like syndrome) took place in a hotel in Beijing. An epidemiological investigation and bacteriological examination were carried out in this hotel. The results showed that it was an outbreak of Legionnaires' disease caused by Legionella pneumophila serogroup 10 (Lp10): The incidence was 13.51% (5/37). This is the first report on LP10 infection in China.

[Alpha 2 megaloglobulin inhibits the activation of rabbit platelet by Chinese Agkistrodon acutus venom]

An in vitro study of alpha 2-mengaloglobulin (alpha 2MG) in the inhibition of the activation of washed rabbit platelet by Chinese Agkistrodon acutus venom (CAAV) was reported. Results showed that CAAV induced aggregation rate of washed rabbit platelet was positively related to the CAAV concentration, and the maximal aggregation rate was 43.8 +/- 9.9% at the concentration of 100 micrograms/ml. Meanwhile the release of serotonin (5-HT) and platelet factor 4(PF4) from the platelet reached maximum at the CAAV concentrations of 0.81 +/- 0.07 microgram/ml and 39.08 +/- 2.78%, respectively. Platelet aggregation and the release of 5-HT and PF4 induced by CAAV could be inhibited by the addition of 0.25% alpha 2 MG into the platelets both 1 minute before and 1 minute after the addition of CAAV. When alpha 2 MG was added to the platelets 1 minute prior to the addition of CAAV, the platelet aggregation and the ultrastructural changes which could be induced by CAAV were not observed, and the morphology of the rabbit platelets was the same as that of the normal counterparts.

Reexamination of gene targeting frequency as a function of the extent of homology between the targeting vector and the target locus

Mutations were targeted to the Hprt locus of mouse embryo-derived stem cells by using 22 different sequence replacement and sequence insertion vectors. The targeting frequency was examined at two sites within the Hprt locus as a function of the extent of homology between the targeting vector and the target locus. The targeting frequency was also compared by using vectors prepared from isogenic and nonisogenic DNA sources. With one exception, all of the vectors showed the same exponential dependence of targeting efficiency on the extent of homology between the targeting vector and the target locus. This was true regardless of whether they were sequence replacement or sequence insertion vectors, whether they were directed toward either of the two different sites within the Hprt locus, or whether they were prepared from isogenic or nonisogenic DNA sources. Vectors prepared from isogenic DNA targeted four to five times more efficiently than did the corresponding vectors prepared from nonisogenic DNA. The single case of unexpectedly low targeting efficiency involved one of the vectors prepared from nonisogenic DNA and could be attributed to an unfavorable distribution of heterology between the Hprt sequences present in the targeting vector and the endogenous Hprt gene.

High-fidelity gene targeting in embryonic stem cells by using sequence replacement vectors

Mutations were targeted to the Hprt locus in murine embryonic stem cells by using sequence replacement vectors. When the vector was designed such that the mutated sequences were flanked on both sides by several kilobases of DNA homologous to the target locus, replacement of chromosomal sequences with the exogenous DNA occurred with precision. If, on the other hand, the target-homologous DNA on one arm of the vector was reduced to below 1 kb in length, the fidelity of recombination was diminished.

Overlap of somatic and visual response areas in the Wulst of pigeon

The somatic and visual response areas of the Wulst were investigated electrophysiologically in pigeons. Somatosensory neurons are distributed in the hyperstriatum accessorium (HA), the hyperstriatum intercalatus superior (HIS) and the hyperstraitum dorsal (HD), mainly in HA. The radial nerve response area is relatively larger and overlaps the sciatic nerve area. Visual neurons are located in HA, especially the more superficial part of HA. In the Wulst, the somatic response area overlaps the visual area and there is somatosensory-visual convergence.

[The influence of Chinese Agkistrodon acutus enzyme (CAAE) on the functions of washed human platelets]

The effects of the activation and influence of CAAE on washed human platelets were investigated. Our findings were: (1) CAAE could induce aggregation and alpha-granule release reaction in the washed human platelet suspension; thus it could activate the platelets; (2) the aggregation effect of CAAE was inhibited by albumin and affected by Ca2+, Mg2+ concentration; (3) heparin and/or AT III did not inhibit the aggregation activation of CAAE, but alpha 2MG markedly inhibited it; (4) the aggregation activity of CAAE was associated with the serine protease activity. The mechanism of CAAE-induced aggregation mainly follows the prostaglandins-endoperoxides thromboxane A2 pathway.

Anterior lentiplane and posterior lenticonus in two cases

Posterior lenticonus has been reported by ophthalmologists, but anterior lentiplane never. Anterior lentiplane, whose characteristic is the flat or plane anterior capsule, has been discovered only recently. It is a special kind of congenital lens anomaly which may be in association with hyperplasia of the lens.

The Kangmar Dome: A Metamorphic Core Complex in Southern Xizang (Tibet)

The Kangmar metamorphic-igneous complex is one of the most accessible examples of an enigmatic group of gneiss domes (the North Himalayan belt) that lies midway between the Greater Himalaya and the Indus-Tsangpo suture in southern Tibet. Structural analysis suggests that the domal structure formed as a consequence of extensional deformation, much like the Tertiary metamorphic core complexes in the North American Cordillera. Unlike its North American counterparts, the Kangmar dome developed in an entirely convergent tectonic setting. The documentation of metamorphic core complexes in the Himalayan orogen supports the emerging concept that extensional processes may play an important role in the evolution of compressional mountain belts.

[Projection of afferent impulses from the brachial plexus and sciatic nerve to the corpus striatum in pigeons]

The corpus striatum were systematically explored by recording averaged potentials elicited by stimulation of the brachial plexus and sciatic nerve in 53 pigeons. It was found that the projection areas of brachial afferents were located within the neostriatum, the hyperstriatum and the ectostriatum. The sciatic projection areas overlap with the brachial projection areas in the neostriatum and a part of the hyperstriatum. Moreover, the brachial and sciatic projection are as in the striatum receive the inputs from both sides of the body. We suggest that the somatic projection areas of fore- and hindlimb are distributed diffusely in the striatum of the pigeon. That the projection area of forelimb is relatively larger is probably related with functional differentiation of the forelimb. Furthermore, the convergence of afferent impulses originating in the different regions of the body within the same brain area may be important for the integration of limb activities in pigeon.

Monoclonal antibody specific for human T acute lymphoblastic leukaemia

A cytotoxic mouse monoclonal antibody (CALL2) was produced against a cultured T acute lymphocytic leukaemia (T ALL) cell line 8402. Ascites fluid containing the antibody was cytotoxic to a titre of up to 1:100 000 against 4 of 6 cultured T ALL cell lines and against leukaemia cells from 7 of 8 T ALL patients and 1 of 5 T chronic lymphatic leukaemia patients. The antibody did not react with normal peripheral-blood T and B lymphocytes, monocytes, granulocytes, spleen cells, thymocytes, platelets, and other acute and chronic leukaemia cells. The CALL2 antibody did not react with bone marrow stem cells of the myeloid series (CFU-C). This antibody may be useful for passive immunotherapy trials since it does not react with normal cells and is highly cytotoxic to T ALL cells.

Cytotoxic monoclonal antibody to a human leiomyosacoma

A monoclonal antibody produced by the hybridoma technique against a human leiomyosarcoma was highly cytotoxic in dilutions of 1:64 000 to the original tumour cells. The antibody was unreactive with most normal cells (lymphocytes, 120 donors; spleen cells, 73/75; monocytes, 16; granulocytes, 25; platelets, 12; red cells, 11) and could not be absorbed out by smooth muscle from the small intestine or by spleen cells. Its specificity for the tumour was high since it did not react with cells from 40 patients with leukaemia, from 8 patients with other tumours, and from 7 cultured tumour lines. The only other cell that it reacted with (at 1:4000 dilution) was line 8402, a T acute lymphocytic leukaemia line. This monoclonal antibody may be suitable for therapeutic trials.