[Studies of magnetic circular dichroism and absorption spectra in alpha-NisO4 x 6H2O crystal]

Alpha-NiSO4 x 6H2O crystals were studied by magnetic circular dichroism (MCD) and absorption spectra measurements in the range lambda = 185-3300nm. The results show that there are three aborption bands, of which the peaks are related to the d-d transitions from the ground state to the excited states. The weak peaks of a progression of the three members were observed between the principal structures lambda = 654nm and lambda = 713nm due to spin-orbit coupling interacion. The weak peaks of a progression of four members were also observed around the new absorption peak at lambda = 585nm in MCD spectra.

The vasoactivity of A beta peptides

We have demonstrated that freshly solubilized A beta peptides can enhance vasoconstriction by phenylephrine or endothelin of isolated rat aorta. Concentrations of peptide producing these effects (100 nM-1 microM) are much lower than those requiring toxicity to endothelial cells in culture, and effects are immediate, not requiring the prolonged time periods for aggregation necessary in A beta cell culture toxicity experiments. Pre-treatment with SOD diminishes the enhancement of vasoconstriction by A beta peptides, suggesting that the effects are partly mediated via a decrease in the nitric oxide/superoxide ratio. Enhancement of endothelin vasoconstriction is observed with A beta 1-40 and A beta 1-42, but not with A beta 25-35 even at 5 microM, again suggesting the mechanism of A beta vasoactivity is distinct from that of A beta cytotoxicity. These observations raise the possibility that A beta peptides in contact with the cerebrovasculature could result in vasoconstriction, hypoperfusion and oxygen free radical imbalance contributing to the neurodegeneration of AD.

Construction of a trivalent candidateShigella vaccine strain with host-vector balanced-lethal system

A trivalent liveShigella vaccine candidate FSD01 against S.flexneri 2a, S.sonnei and S.dysenteriae I was constructed. This candidate strain was based on the S.flexneri 2a vaccine T32. By homologous recombination exchange, the chromosomalasd gene of T32 was site-specifically inactivated, resulting in the strain unable to grow normally in LB broth, while anotherasd gene of S.mutans was employed to construct an Asd(+) complementary vector. This combination ofasd (-) host/Asd(+) vector formed a balanced-lethal expression system in T32 strain. By use of this system, two important protective antigen genes coding for S.sonnei Form I antigen and Shiga toxin B subunit were cloned and expressed in T32, which led to the construction of trivalent candidate vaccine FSD01. Experimental results showed that this strain was genetically stable, but its recombinant plasmid was non-resistant. Moreover, it was able to effectively express trivalent antigens in one host and induce protective responses in mice against the challenges of the above threeShigella strains.

Construction of a recombinant human GM-CSF/MCAF fusion protein and study on itsin vitro andin vivo antitumor effects

A novel cytokine fusion protein was constructed by fusing granulocyte macrophage colony stimulating factor (GM-CSF) with monocyte chemotactic activating factor (MCAF), which acts as a factor directing effector cells (monocytes) to a target site. The recombinant human GM-CSF/MCAF fusion protein could sustain the growth of GMCSF-dependent cell line TF1 and was chemotactic for monocytes. Thein vitro antitumor effect showed that rhGM-CSF/MCAF could activate monocytes to inhibit the growth of several human tumor cell lines, including a promyelocyte leukemia cell line HL-60, a lung adenocarcinoma cell line A549, a hepatoma cell line SMMC-7721 and a melanoma cell line Bowes. Furthermore, the cytotoxicity of monocytes activated by rhGM-CSF/MCAF against HL-60 and A549 was greater than that activated by GM-CSF or MCAF alone, even greater than that activated by a combination of GM-CSF and MCAF, suggesting that the fusion protein has synergistic or enhanced effects. Thein vivo antitumor effect indicated that rhGM-CSF/MCAF had marked antitumor effect against A549 tumor in nude mice and even completely suppressed tumor formation. rhGM-CSF/MCAF was significantly more effective in inhibiting tumor growth than rhGM-CSF. Histological analysis showed that tumor site injected with rhGM-CSF/MCAF was infiltrated by a large number of monocytes while a sparse infiltration of monocytes was observed at the tumor site injected with rhGM-CSF or normal saline, suggesting that the antitumor effect of rhGM-CSF/MCAF was mediated by the recruitment of a large number of monocytes to the tumor site.

Relationship of whole-blood FK506 concentrations to rejection and toxicity in liver and kidney transplants

FK506 (tacrolimus) has been shown to be a safe and effective immunosuppressant for the prevention of organ rejection after liver and kidney transplantation. Like cyclosporine, the use of FK506 has been associated with some adverse effects such as toxicity and organ rejection. Therapeutic monitoring of the whole-blood FK506 drug concentrations has been used in an effort to determine how the concentration of FK506 in the blood is related to the development of toxicity or the risk for organ rejection. Cox regression analysis of two recent clinical trials of FK506 in patients receiving kidney and liver transplants shows a significant correlation between the whole-blood FK506 concentrations and the incidence of both toxicity and organ rejection. Because of these relationships and the pharmacokinetics of FK506, therapeutic monitoring of the whole-blood FK506 levels is expected to be helpful for minimizing the risks of both toxicity and rejection in liver and kidney transplants.

[A preliminary report on changes in micro-circulation of conjunctiva in patients with high altitude pulmonary edema]

Micro-circulation of conjunctiva was investigated in 36 patients with high altitude pulmonary edema (HAPE) and 21 healthy subjects who arrived recently in high land and were the controls, and plasma angiotensin II (AT II) and aldosterone (ALD) were determined in 16 patients with HAPE and in the control group. The results show that the concentrations of plasma AT II, ALD in patients with HAPE are obviously higher than those of the healthy individuals (P < 0.001), the degree of changes in micro-circulation of conjunctiva in patients with HAPE is directly proportional to the degree of severity of HAPE, and the higher the concentrations of plasma AT II and ALD, the severer the degree of changes in micro-circulation.

Oncogenic mutations in the rb1 gene in retinoblastoma tumors from patients from the kingdom of saudi-arabia

Five retinoblastoma tumours from patients treated in the King Khaled Eye Specialist Hospital in Riyadh were analysed for mutations in the RB1 gene using single strand conformation polymorphism analysis and mutations were found in all of them. In one tumour the mutation in exon 11 was homozygous demonstrating the role of loss of heterozygosity in tumorigenesis. The mutation in the remaining 4 tumours were heterozygous and in only one case were two independent mutations found. Three mutations were insertions or deletions and the other three were point mutations of which 5 resulted in the generation of premature stop codons within the coding region of the gene and one is predicted to affect the correct splicing of the pre-mRNA. The nature of the mutations found in this series of patients from the Kingdom of Saudi Arabia, therefore, are similar to those found in other populations throughout the world and show no evidence for mutation hotspots within the RB1 gene.

[Oligonucleotide directed in vitro mutagenesis]

In this study, a method for oligonucleotide directed in vitro mutagenesis was described. It includes the following steps: clone of the gene to be mutated into the phagemid pGCI; preparation of single strand template; design and synthesis of mutated oligonucleotides; synthesis of double strand DNA. Using this method, a new BamHI site was originated at the N terminal of Stx-B and BglII site at the C terminal of Stx-B. It is ready to fuse the Stx-B gene to LamB. This method is a very useful tool for genetic engineering.