[UV photolysis mechanism of CCl4 and CHCl3 in water]

The photolysis mechanism of CCl4 and CHCl3 in water was studied by using transient absorption spectra. The results showed that aqueous CCl4 was dissociated into CCl3 and Cl radicals by 248 nm laser, and CHCl3 was dissociated into CHCl2 and Cl radicals after adding C6H6. The radicals CCl3 and CHCl2 were able to react with O2 to form CCl3O2 and CHCl2O2 respectively, or to form C2Cl6 and C2H2Cl4 without O2. The rate coefficients of some reactions were obtained.

Three-dimensional control of light in a two-dimensional photonic crystal slab

Optoelectronic devices are increasingly important in communication and information technology. To achieve the necessary manipulation of light (which carries information in optoelectronic devices), considerable efforts are directed at the development of photonic crystals--periodic dielectric materials that have so-called photonic bandgaps, which prohibit the propagation of photons having energies within the bandgap region. Straightforward application of the bandgap concept is generally thought to require three-dimensional (3D) photonic crystals; their two-dimensional (2D) counterparts confine light in the crystal plane, but not in the perpendicular z direction, which inevitably leads to diffraction losses. Nonetheless, 2D photonic crystals still attract interest because they are potentially more amenable to fabrication by existing techniques and diffraction losses need not seriously impair utility. Here we report the fabrication of a waveguide-coupled photonic crystal slab (essentially a free-standing 2D photonic crystal) with a strong 2D bandgap at wavelengths of about 1.5 microm, yet which is capable of fully controlling light in all three dimensions. These features confirm theoretical calculations on the possibility of achieving 3D light control using 2D bandgaps, with index guiding providing control in the third dimension, and raise the prospect of being able to realize unusual photonic-crystal devices, such as thresholdless lasers.

[A preliminary study on placenta hematopoiesis]

OBJECTIVE

To study the role of placenta on fetal hematopoiesis during embryo ontogeny, so as to find a new source of hematopoietic stem/progenitor cells (HSC/HPC) for clinical transplantation.

METHODS

Cord blood was collected separately from cord vein and artery. CD(34)(+) cells were detected by FACS, CFU-GM semisolid agar culture, and hematopoietic growth factors (HGFs) by ELISA. The results of HE stain and CD(34) McAb immunohistochemistry stain of placenta chorionic villi were investigated.

RESULTS

The CFU-GM yields and the percentage of CD(34)(+) and CD(34)(+)/CD(38)(minus sign) cells in cord vein were higher than that in artery. The cord vein contained larger amount of hematopoietic stimulating factors and similar level of hematopoietic inhibitory factors as compared with that in artery. Blood island, reticular cells and scattered CD(34)(+) cells were found in the mesenchyme of placenta chorionic villi.

CONCLUSION

The placenta might be an another hematopoietic organ in ontogeny. It could be applied to clinical hematopoietic cell transplantation.

MutS homolog 4 localization to meiotic chromosomes is required for chromosome pairing during meiosis in male and female mice

Msh4 (MutS homolog 4) is a member of the mammalian mismatch repair gene family whose members are involved in postreplicative DNA mismatch repair as well as in the control of meiotic recombination. In this report we show that MSH4 has an essential role in the control of male and female meiosis. We demonstrate that MSH4 is present in the nuclei of spermatocytes early in prophase I and that it forms discrete foci along meiotic chromosomes during the zygotene and pachytene stages of meiosis. Disruption of the Msh4 gene in mice results in male and female sterility due to meiotic failure. Although meiosis is initiated in Msh4 mutant male and female mice, as indicated by the chromosomal localization of RAD51 and COR1 during leptonema/zygonema, the chromosomes fail to undergo normal pairing. Our results show that MSH4 localization on chromosomes during the early stages of meiosis is essential for normal chromosome synapsis in prophase I and that it acts in the same pathway as MSH5.

Observation of vibrational excitation and deexcitation for NO (v = 2) scattering from au(111): evidence for electron-hole-pair mediated energy transfer

Measurements of vibrational excitation and deexcitation of NO (v = 2) scattering from a Au(111) surface show that the probability of both processes increases strongly with the kinetic energy of the incident NO. These results are qualitatively consistent with a vibrational energy transfer mechanism involving electron-hole pairs but not with competing adiabatic models. The form of the energy dependence, and other features of the measurements, are not in accord with existing calculations.

Cardiac defects and renal failure in mice with targeted mutations in Pkd2

PKD2, mutations in which cause autosomal dominant polycystic kidney disease (ADPKD), encodes an integral membrane glycoprotein with similarity to calcium channel subunits. We induced two mutations in the mouse homologue Pkd2 (ref.4): an unstable allele (WS25; hereafter denoted Pkd2WS25) that can undergo homologous-recombination-based somatic rearrangement to form a null allele; and a true null mutation (WS183; hereafter denoted Pkd2-). We examined these mutations to understand the function of polycystin-2, the protein product of Pkd2, and to provide evidence that kidney and liver cyst formation associated with Pkd2 deficiency occurs by a two-hit mechanism. Pkd2-/- mice die in utero between embryonic day (E) 13.5 and parturition. They have structural defects in cardiac septation and cyst formation in maturing nephrons and pancreatic ducts. Pancreatic ductal cysts also occur in adult Pkd2WS25/- mice, suggesting that this clinical manifestation of ADPKD also occurs by a two-hit mechanism. As in human ADPKD, formation of kidney cysts in adult Pkd2WS25/- mice is associated with renal failure and early death (median survival, 65 weeks versus 94 weeks for controls). Adult Pkd2+/- mice have intermediate survival in the absence of cystic disease or renal failure, providing the first indication of a deleterious effect of haploinsufficiency at Pkd2on long-term survival. Our studies advance our understanding of the function of polycystin-2 in development and our mouse models recapitulate the complex human ADPKD phenotype.

Essential role for Max in early embryonic growth and development

Loss of Max function in the mouse resulted in generalized developmental arrest of both embryonic and extraembryonic tissues at early postimplantation (approximately E5.5-6.5), coincident with loss or dilution of maternal Max stores in the expanding embryo in vivo and in blastocyst outgrowths in vitro. Developmentally arrested embryos were reduced in size and exhibited widespread cytological degeneration and feeble BrdU incorporation. Max and, by extension, the Myc superfamily, serve essential roles in early mammalian development and a maternal reservoir of Max exists in sufficient amount to sustain Myc superfamily function through preimplantation stages of development.

Preparation and identification of activity of anti-HPV-6b/11E1 universal ribozyme--Rz1198 in vitro

AIM

To study the preparation and cleavage activity of Rz1198 directed against HPV-6bE1 and HPV-11E1 (HPV-6b/ 11E1) transcripts in vitro.

METHODS

HPV-6b/11E1 gene fragments were cloned into T-vector under the control of T7 promoter. 32P-labeled HPV-6b/11E1 transcripts as target-RNAs were transcribed in vitro and purified by PAGE. Rz1198 gene designed as a universal ribozyme for both HPV-6b/11E1 transcripts was cloned into vector p1.5 between 5'-cis-Rz and 3'-cis-Rz. 32P-labeled Rz1198 transcript was gel-purified, incubated with target-RNAs at different conditions and autoradiographed after denaturing gel-electrophoresis.

RESULTS

Rz1198 was active at 37 degrees C. The optimal temperature was 50 degrees C. For HPV-6bE1, km = 12.2 nmol/L, kcat = 0.18 min(-1); For HPV-11E1, km = 14.7 nmol/L, kcat = 0.14 min(-1). All these revealed that the design of Rz1198 was correct. It could be a universal ribozyme for the two substrates--HPV-6bE1 and HPV-11E1 transcripts.

CONCLUSION

Rz1198 prepared in vitro possesses the perfect specific catalytic cleavage activity. It leads to the expectation that, in the future, it will be possible to develop a new nucleic acid drug from Rz1198 which can efficiently inhibit the replication of HPV-6b/11 DNA in vivo.

[Forty-seven cases of lower respiratory tract infections due to E. ictaluri]

OBJECTIVE

To study the risk factors and treatment of lower respiratory tract infections due to E. ictaluri, and the cause of its improved detection by sputum culture in recent years.

METHODS

To sum up the number of positive cultures and analyze the clinical features of the cases with positive sputum culture tested from 1959 to 1998.

RESULTS

Before 1996, there were no positive cultures (0%) in 17,500 sputum samples using manual techniques, in 1997 and 1998 the aggregate positive rate was 2.3% (47/1,962), using SCEPTOR detecting instrument. On chi square testing of the two results derived from the two methods, P < 0.001. On drug sensitivity testing, E. ictaluri was sensitive to imipenem, cefotaxime and tobramycin.

CONCLUSIONS

E. ictaluri is an uncommon opportunistic pathogen of lower respiratory tract infections. Lowered body resistance is a risk factor, and improved technology is the principal cause for detection of E. ictaluri infections.

[A Raman spectral studies of rare-earth (REE) fluoro-carbonate minerals]

The Raman spectra of REE fluoro-carbonate minerals were studies by a type of RIT-30 laser Raman spectrometer. On the basis of Raman spectral properties, REE fluoro-carbonate minerals can be divided into three groups: Ba-REE fluoro-carbonate mineral, Ca-REE fluoro-carbonate mineral and REE fluoro-carbonate mineral. Obviously, a differential kind of mineral is different in the vibration frequency of the Raman spectra. They are as follows: Cordylite v1-1 088, v2-967, v3-1 538, v4-720, 628; Hauheite v1-1 089,v3-1 525, 1 596, v4-720, 649; Cerbaite v1-1 088, v2-911, v3-1 516, v4-718,625; Parisite v1-1 095,1 075, v2-915, v3-1 461, v4-744, 732; Bastnesite v1-1 098, v2-835, v3-1 476, 1 447, v4-732.

Enhanced reactivity of highly vibrationally excited molecules on metal surfaces

The chemical dynamics of highly vibrationally excited molecules have been studied by measuring the quantum state-resolved scattering probabilities of nitric oxide (NO) molecules on clean and oxygen-covered copper (111) surfaces, where the incident NO was prepared in single quantum states with vibrational energies of as much as 300 kilojoules per mole. The dependence of vibrationally elastic and inelastic scattering on oxygen coverage strongly suggests that highly excited NO (v = 13 and 15) reacts on clean copper (111) with a probability of 0.87 +/- 0.05, more than three orders of magnitude greater than the reaction probability of ground-state NO. Vibrational promotion of surface chemistry on metals (up to near-unit reaction probability) is possible despite the expected efficient relaxation of vibrational energy at metal surfaces.

[The relationship between operation on gastrointestinal cancer and single cells metastasis via portal vein]

OBJECTIVE

To confirm the effect of radical operation on single cells metastasis of gastrointestinal cancer.

METHODS

One hundred and seventy two patients with gastrointestinal cancer were divided randomly into group I (111 cases, ordinary operation) and group II (61 cases, operation after ligation of drained vessels). Catheters were inserted into the portal vein during operation. Blood was aspirated and contrifugated. Anti-EMA monoclonal antibody marked the cancer cells, which were shown by ABC immunohistochemical staining.

RESULTS

In the examinate group, 72 cases of gastrointestinal cancer were found positive cells among 111 cases (positive rate 64.9%). In the control group, 61 cases were tested and 13 cases were found positive cells (positive rate 21.3%) with a highly significant difference between the two groups (P < 0.005).

CONCLUSIONS

Ligating the relative blood vessel before the radical operation can prevent single cancer cells from metastasis via portal vein.

[Phase variation in Salmonella typhimurium phagetype]

The phase variation of phagetype was observed in cultures of Salmonella typhimurium collected from Xinjiang Uygur Autonomous Region during 1980-1993. A few cultures of phagetype 4774 or 4776(full type) may change into another phagetype, i.e. 4000(phase 1) or 0774 and 0776 (phase 2). In reverse, more strains of these phagetype 4000 and 0774(0776) easily back into their original phagetype 4774 or 4776. But some 4000(phase 1) can change to 0776(phase 2), and some 0774(phase 2) can also change to 4000(phase 1). Similarly, a few cultures of phagetype 7776(full type) can change to 7000(phase 1) or 0776(phase 2). More strains of these phagetype 7000(or 7002) and 0776 reverse easily to their original phagetype 7776 or 7774. The variability is 15.6% from full type to phase 1 or phase 2, and is 53.2% from phase 1 or phase 2 to full type. Understanding of phase variation of Salmonella typhimurium phagetype will be helpful to Salmonella phagetyping, and will be significance on epidemiological analysis of Salmonella infection.

Role of Mxi1 in ageing organ systems and the regulation of normal and neoplastic growth

Mxi1 belongs to the Mad (Mxi1) family of proteins, which function as potent antagonists of Myc oncoproteins. This antagonism relates partly to their ability to compete with Myc for the protein Max and for consensus DNA binding sites and to recruit transcriptional co-repressors. Mad(Mxi1) proteins have been suggested to be essential in cellular growth control and/or in the induction and maintenance of the differentiated state. Consistent with these roles, mxi1 may be the tumour-suppressor gene that resides at region 24-26 of the long arm of chromosome 10. This region is a cancer hotspot, and mutations here may be involved in several cancers, including prostate adenocarcinoma. Here we show that mice lacking Mxi1 exhibit progressive, multisystem abnormalities. These mice also show increased susceptibility to tumorigenesis either following carcinogen treatment or when also deficient in Ink4a. This cancer-prone phenotype may correlate with the enhanced ability of several mxi1-deficient cell types, including prostatic epithelium, to proliferate. Our results show that Mxi1 is involved in the homeostasis of differentiated organ systems, acts as a tumour suppressor in vivo, and engages the Myc network in a functionally relevant manner.

Somatic inactivation of Pkd2 results in polycystic kidney disease

Germline mutations in PKD2 cause autosomal dominant polycystic kidney disease. We have introduced a mutant exon 1 in tandem with the wild-type exon 1 at the mouse Pkd2 locus. This is an unstable allele that undergoes somatic inactivation by intragenic homologous recombination to produce a true null allele. Mice heterozygous and homozygous for this mutation, as well as Pkd+/- mice, develop polycystic kidney and liver lesions that are indistinguishable from the human phenotype. In all cases, renal cysts arise from renal tubular cells that lose the capacity to produce Pkd2 protein. Somatic loss of Pkd2 expression is both necessary and sufficient for renal cyst formation in ADPKD, suggesting that PKD2 occurs by a cellular recessive mechanism.

Altered cell differentiation and proliferation in mice lacking p57KIP2 indicates a role in Beckwith-Wiedemann syndrome

Mice lacking the imprinted Cdk inhibitor p57(KIP2) have altered cell proliferation and differentiation, leading to abdominal muscle defects; cleft palate; endochondral bone ossification defects with incomplete differentiation of hypertrophic chondrocytes; renal medullary dysplasia; adrenal cortical hyperplasia and cytomegaly; and lens cell hyperproliferation and apoptosis. Many of these phenotypes are also seen in patients with Beckwith-Wiedemann syndrome, a pleiotropic hereditary disorder characterized by overgrowth and predisposition to cancer, suggesting that loss of p57(KIP2) expression may play a role in the condition.

Role for N-CoR and histone deacetylase in Sin3-mediated transcriptional repression

Normal mammalian growth and development are highly dependent on the regulation of the expression and activity of the Myc family of transcription factors. Mxi1-mediated inhibition of Myc activities requires interaction with mammalian Sin3A or Sin3B proteins, which have been purported to act as scaffolds for additional co-repressor factors. The identification of two such Sin3-associated factors, the nuclear receptor co-repressor (N-CoR) and histone deacetylase (HD1), provides a basis for Mxi1/Sin3-induced transcriptional repression and tumour suppression.

[Determination of caffeine and sodium benzoate contents in caffeine and sodium benzoate injection by P-matrix method]

The contents of caffeine and sodium benzoate injection may be determined by P-matrix method without separation of its components. BSAIC language is used for programming. The average recovery of caffeine is 100.0% and that of sodium benzoate is 99.95%. The variation coefficient of caffeine is 0.40% and that of sodium benzoate is 0.65%. On the basis of recovery rate and data observed it is concluded that this method is accurate, reliable, simple and rapid as compared with the standard pharmacopoeia regulations.

[Experimental study of immunity in anti-plasmodium infection on preserved spleen and splenectomized mice]

OBJECTIVE

To investigate the function of the spleen as well as the changes of splenic function after hemisplenectomy and hemisplenic autotransplanted in plasmodium yoelili infected mice (first and second infection).

METHODS

336 mice were divided into six groups: 1. total splenectomy, 2. hemisplenectomy, 3. hemisplenic autotransplanted, 4. sham-operation, 5. total splenectomy of 2nd infection, 6. sham-operation of the 2nd infection. 3 months after operation (1-4) or 15 day after 1st infection and operation (5-6) in mice intraperitoneal inoculations were initiated.

RESULTS

1. First infection: in total splenectomy group the antiplasmodium antibody reduced, the remanent rate of 51Cr-RBC in circulation was high, RBC count continously decreased, parasitized erytrocytes still were seen after 1 month. These changes were mild in the preserved spleen. But the production of antiplasmodium antibody and spleen uptake rate of 51Cr-RBC of the hemisplenic autotrans aplaned were rather lower than those of the shamoperate group. 2. Second lethal yoelli infection: in the mice of shamoperation of 2nd yoelii infection the parasitized erytrocyte was lower than that of shamoperated group, but the higher level antiplasmodium antibody and uptake rates of 51Cr-RBC of unit weight splenic tissue.

CONCLUSIONS

Under the plasmodium infection preserved hemispleen alternate normal spleen to play the immunologic role, splenic tissue autotransplantation can fairly restore the partial function of spleen. Different preserved spleen method is a useful operation for clinic.

Pasteurization of eggs in the shell

A small percentage of all eggs may be contaminated with Salmonella enteritidis (SE). To eliminate this hazard from the food supply, procedures for pasteurizing eggs in the shell have been developed. At least four research groups are attempting to devise a process to achieve a pasteurized shell egg. Only one of the groups has reported procedures and results. Sound shell eggs were washed to remove surface contaminants. The clean eggs were then inoculated with high levels of SE cells. The inoculated eggs were then heated by one of several means to a yolk temperature of about 55 C and held at that temperature for varying periods of time. The number of surviving cells was determined. It is possible to obtain a 7 log cycle reduction of SE in inoculated eggs without a significant change in functional or visual quality of the eggs.