[Parameters of arterial occlusion during intracranial aneurysm surgery]

OBJECTIVE

To evaluate parameters, owing to temporary and/or permanent intraoperative arterial occlusion, could be related to the postoperative development of ischemic injury.

METHOD

During 3-year period between October 1994 and March 1997, 27 patients with intracranial aneurysm were operated on with the aid of temporary and/or permanent arterial occlusion. Continuous intraoperative monitoring lCBF of the territories undergoing occlusion was carried out using LDF. Univariate analysis was used to study the relationship between the study variable and cerebral infarction. These variables included patient age, sexuality, aneurysm size, preoperative Hunt and Hess grades, LDF baseline value, LDF value following arterial occlusion and release of occlusion, the duration of arterial occlusion, the numbers of occlusive episodes, and the degree of arterial occlusion. Student's t-test was used for comparison of continuous variable such as age, and chi-square analysis was used to test the association of categorical variables.

RESULT

The LDF value following arterial occlusion or residual lCBF, the duration of arterial occlusion, the numbers of occlusive episodes, and the occlusive degree were found to be significantly related to the postoperative development of ischemic injury.

CONCLUSION

The residual lCBF and collateral circulation following arterial occlusion can be evaluated using LDF monitoring. When residual lCBF is more than 50 per cent of the baseline and the duration of arterial occlusion less than 20 minutes, temporary arterial occlusion is safe and does not develop postoperative ischemic injury.

RNA enzymes with two small-molecule substrates

BACKGROUND

The 'RNA world' hypothesis posits ancient organisms employing versatile catalysis by RNAs. In particular, such a metabolism would have required RNA catalysts that join small molecules. Such anabolic reactions now occur very widely, for example in phospholipid, terpene, amino acid and nucleotide synthetic pathways in modern organisms. Present RNA systems, however, do not perform such reactions using substrates that do not base pair. Here we ask whether this lack is a methodological artifact due to the practice of selection-amplification, or a fundamental property of active sites reconstructed within RNA structures.

RESULTS

Three rationally modified RNA enzymes, Iso6-G, Iso6-2G and Iso63G, catalyze the formation of (5'-->5') polyphosphate-linked oligonucleotides in trans. One of these, Iso6-G RNA, has a specific substrate site for a guanosine triphosphate, GTP, dGTP or ddGTP, and one nonspecific substrate site for a terminal-phosphate-containing small molecule. This ribozyme catalyzes multiple turnovers, proceeding at a constant rate. Guanosine specificity is probably not attributable to Watson-Crick base pairing.

CONCLUSIONS

Ribozymes can readily bind multiple small-molecule substrates simultaneously and catalyze reactions that build up larger products, apparently independent of substrate-RNA Watson-Crick base pairing. RNA enzymes therefore parallel proteins, which often overcome the entropic difficulties of positioning multiple small substrates for catalysis of anabolic reactions. These results support the idea of a complex ancestral metabolism based on RNA catalysis.

[Restoration of supination of forearm by flexor carpi radialis transfer]

The dysfunction of supination of forearm following injury of brachial plexus or poliomyelitis always affects the function of hand. To find the dynamic muscle for restoration of the supination, the flexor carpi radialis was investigated on fifty male cadavers. The blood supply of the muscle was polygenic, mainly derived from the humoral and radial arteries. The movement of the muscle was innervated by median nerve. If the proximal 1/3 belly of the muscle was reserved, the blood supply and innervation of the complete muscle was reserved. According to the anatomic data, the operative procedure was designed as following: transfer the distal 2/3 of flexor carpi radialis over the ulnar aspect of the forearm to the dorsal-radial side, the tendon was fixed on the radius shaft 6 to 10 cm proximal to the styloid process with forearm in full supination. Four patients were treated and after followed up for 3.2 years average, the supination restored. It was discussed that in case of paralysis of the flexor carpi ulnaris and pronator teres, the optimal choice to restore the supination would be flexor carpi radialis.

[Genetic polymorphisms of TH01 and VWA loci in Tibetans in China]

OBJECTIVE

To understand the genetic relationship between Han population and Tibetan population, the genetic polymorphisms of two STR loci, TH01 and VWA were studied in the Tibetans in China.

METHODS

EDTA-blood specimens were collected from 89 healthy unrelated Tibetan individuals in Lasa. DNA was extracted using Chelex method. The DNA samples were amplified by PCR technique, and the PAGE horizontal electrophoresis were used to typing the PCR products.

RESULTS

There were five alleles at TH01 locus in Tibetan population. The alleles frequencies were TH01*6:0.097, TH01*7:0.227, TH01*8:0.091, TH01*9:0.481 and TH01*9.3:0.104. A total of 12 genotypes were observed in 77 individuals for TH01. For VWA locus there were seven alleles and the allele frequencies were VWA *14:0.101, VWA*15:0.034, VWA*16:0.208, VWA*17:0.303, VWA*18:0.208, VWA*19:0.129 and VWA*20:0.017. A total of 20 genotypes for VWA were observed in 89 individuals. The results of test for Hardy-Weinberg equilibrium showed that the genotype distributions observed at both STR loci were correspondent with those expected(chi-square =7.421 df =8 P>0.05 for TH01; chi-square =19.61 df =14 P>0.05 for VWA).

CONCLUSION

There is no significant difference between Han and Tibetan populations in allele frequencies at TH01 and VWA loci. The results of analysis using genetic distance and phylogenetic tree indicate that Tibetan population is identical with Han population at TH01 and VWA loci .

Transzygomatic coronoidectomy through an extended coronal incision for treatment of trismus due to an osteochondroma of the coronoid process of the mandible

Osteochondroma is the most common benign tumor of the skeletal system. In the craniofacial skeleton, however, osteochondroma is uncommon. Even more rare is osteochondroma of the coronoid process. A review of the literature reveals only 31 reported cases of osteochondroma of the coronoid process of the mandible. The preponderance of patients were young men (67.7%) and most presented with a facial deformity. As a benign tumor, the problems with surgical treatment have dealt with the inaccessibility of the lesion and hence the surgical approach of choice. The previous surgical approaches have either been intraoral, external, or a combination of both. We present a transzygomatic approach via a coronal incision that gives excellent access and a good cosmetic result, and protects the facial nerve from damage.

U-74389G suppresses lipid peroxidation and apoptosis following focal cerebral ischemia and reperfusion in rats

OBJECTIVE

To study the antioxidant and antiapoptotic effects of U-74389G on ischemic brain in rats.

METHODS

Right focal cerebral ischemia and reperfusion was induced by suturing in 103 male SD rats weighing 280-310 g. To determine LPO in the cortex and striatum, we randomly divided 78 rats into 5 groups: group 1, sham-operative group (6 rats); group 2, control (18); group 3, U-74389G administration before ischemia (18); group 4, U-74389G administration before reperfusion; group 5, CS-4 vehicle as negative control. Groups 2-5 were further divided into 3 subgroups according to the duration of reperfusion. Another 25 rats were similarly grouped (5) to detect apoptosis with TUNEL stain.

RESULTS

The concentrations of MDA in groups 3 and 4 were reduced and the activities of SOD and concentrations of GSH were partially restored as compared with the control group. These effects were more significant in group 3 than in group 4. Otherwise, CS-4 can not provide protective effects. The number of apoptotic cells in groups 3 (P < 0.01) and 4 (P < 0.05) was significantly reduced as compared with the control group.

CONCLUSIONS

U-74389G has antioxidant and antiapoptotic effects on ischemic brain in rats. The administration of U-74389G before the onset of ischemia was more useful than that before the onset of reperfusion.

Enhancer control of V(D)J recombination at the TCRbeta locus: differential effects on DNA cleavage and joining

Deletion of the TCRbeta transcriptional enhancer (Ebeta) results in nearly complete inhibition of V(D)J recombination at the TCRbeta locus and a block in alpha beta T cell development. This result, along with previous work from many laboratories, has led to the hypothesis that transcriptional enhancers affect V(D)J recombination by regulating the accessibility of the locus to the recombinase. Here we test this hypothesis by performing a detailed analysis of the recombination defect in Ebeta-deleted (Ebeta-/-) mice using assays that detect various reaction intermediates and products. We found double-strand DNA breaks at recombination signal sequences flanking Dbeta and Jbeta gene segments in Ebeta-/- thymuses at about one-third to one-thirtieth the level found in thymuses with an unaltered TCRbeta locus. These sites are also subject to in vitro cleavage by the V(D)J recombinase in both Ebeta-/- and Ebeta+/+ thymocyte nuclei. However, the corresponding Dbeta-to-Jbeta coding joints are further reduced (by 100- to 300-fold) in Ebeta-/- thymuses. Formation of extrachromosomal Dbeta-to-Jbeta signal joints appears to be intermediately affected and nonstandard Dbeta-to-Dbeta joining occurs at the Ebeta-deleted alleles. These data indicate that, unexpectedly, loss of accessibility alone cannot explain the loss of TCRbeta recombination in the absence of the Ebeta element and suggest an additional function for Ebeta in the process of DNA repair at specific TCRbeta sites during the late phase of the recombination reaction.

Syntagms in development and evolution

The genetic analysis of segmentation, neurogenesis, appendage formation and other developmental processes has revealed that the development of Drosophila can be broken down into discrete elementary operations. Thus development can be viewed as a stepwise process where each step is driven by a small group of genes working interactively. García-Bellido proposed that each of these groups be called a "syntagm". In this review, we will describe a series of developmental syntagms, and explore the consequences of this discontinuous organization of the developmental program on evolution.

[Study on HCV infection and the distribution of HCV genotypes in different populations in Shenyang area]

3,902 serum samples in different populations were tested for anti-HCV by ELISA. Among 100 samples of them, genotypes of HCV were detected by PCR with type-specific primers. The results showed: a) anti-HCV positive rates in general populations were 0.42%-1.66%; b) anti-HCV positive rates in the group of post-transfusion hepatitis and sporadic hepatitis (excluding HAV, HBV, EBV, CMV infection), hepatitis B post hepatitis cirrhosis (excluding HBV infection) and primary hepatocarcinoma were significantly higher than the group of patients without liver diseases or the group of patients without transfusion (P < 0.01); c) in HCV genotyping, HCV-II, HCV-III, II/III mixed type were 58%, 27%, 14% respectively. The rate of infection with HCV-III, was 80% in normal population but 91.7% with type II HCV in the group of patients with cirrhosis. These results suggested: (1) patients with different liver diseases were under high risk of HCV infection; (2) type HCV-II was predominant followed by HCV-III as well as II/III mixed in HCV genotype distribution of Shenyang area. Different genotypes of HCV might be related to the severity of hepatitis C.

Analysis of the 5' flanking sequence of the human norepinephrine transporter gene

The human norepinephrine transporter (NET) gene was cloned and structurally analyzed. The far 5' fragment containing exon 1 (a non-coding exon) and exon 2 was sequenced. The transcription start site of the gene in human brain stem tissue was determined by primer extension analysis. It was found that the gene could be transcribed from multiple starting points. The 5' flanking sequence contains a proximal G-C rich region, one possible GSG element and several SP1 sites. However it does not contain TATA box and CAAT box motifs. Gel shift analysis with nuclear extracts from different tissues of mouse shows that the G-C rich region may be involved in tissue specific expression of the gene.

[The association of HLA-B27 binding peptide and spondylarthropathies]

OBJECTIVE

To explore the association of spondylarthropathies HAL-B27 binding peptide.

METHODS

B27 molecules expressed on the B27-T2 mutant cell line do not have peptides. Such empty B27 molecules were not recognized by peptide-dependent monoclonal antibody, B27.M2. Positive B27.M2 reactivity resulted when B27-T2 cells were incubated with peptide RRKAMFEDI derived from Chlamydia hsp60. THe importance of each residue in RRKAMFEDI was analysed by testing analogs in which each of the 9 residues in the peptide was consecutively substituted by 19 other amino acids.

RESULTS

B27.M2 reactivity was the highest with arginine in second residue. The reactivities of residues other than arginine were less than 30% of the value with the parent peptide.

CONCLUSION

The stringency for other residues was relatively low, indicating that immune recognition of B27-peptide complexes might have rather low stringency for peptide sequences. These peptide residues probably influenced antibody reactivity by inducing conformational changes.

A drug-lipid interaction model: atropine induces interdigitated bilayer structure

X-ray diffraction and fluorescence methods have been carried out to examine the effects of a drug, atropine, on the structure of model membranes: dipalmitoylphosphatidylglycerol(DPPG) multilamella vesicles(MLVs). A structural analysis by small angle x-ray diffraction shows that, with incorporation of atropine, the lamella repeating period of DPPG MLV is decreased from 5.89 nm to 4.52 nm. Using fluorescence probe 1,6-diphenyl-1,3,5-hexatriene(DPH) we find that the fluorescence intensity of DPH reduces largely at a narrow scope of atropine concentration. The experiments of fluorescence polarization of n-(9-anthroyloxyl)-stearic acid (nAS) and 16-(9-anthroyloxyl)-palmiticacid (16AP) discover that the normal polarization gradient almost disappears in DPPG/atropine system. By colligating the above results, we can draw a conclusion that atropine induces the transition from non-interdigitated to interdigitated stricture of DPPG vesicles in gel phase, which provides a sound model of drug-lipid interaction.

Effect of mild hypothermia on the changes of cerebral blood flow, brain blood barrier and neuronal injuries following reperfusion of focal cerebral ischemia in rats

OBJECTIVE

To compare the effects of mild hypothermia induced in different time courses on rats subjected to 3 hours (h) of ischemia followed by 3 h or 72 h of reperfusion.

METHODS

Eighty male Sprague-Dawley rats were divided into three mild hypothermic (MHT, 32 +/- 0.2 degrees C) groups, including intra-ischemia (MHTi), intra-reperfusion (MHTr), and intra-ischemia/reperfusion (MHTi + r) group, and one normothermic group (NT, 37 +/- 0.2 degrees C) as the control. Reversible focal ischemia was carried out in rats with suture model. The cortical blood flow was measured during 3 h of ischemia followed by 3 h of reperfusion. The permeability of brain blood barrier (BBB) was estimated after 3 h of reperfusion. The infarct volume was measured at 72 h after reperfusion to determine the effects of MHT.

RESULTS

The acute post-ischemic hyperperfusion and delayed hypoperfusion in ischemic perifocal region and sustained hypoperfusion in ischemic core were inhibited in MHTi + r and MHTi rats (P < 0.05). MHTi + r protection on post-ischemic progressive hypoperfusion in the perifocal region was more effective than that of MHTi (P < 0.05). The BBB disruption and the infarct volume were significantly reduced in both MHTi and MHTi + r groups (P < 0.05), especially in the MHTi + r rats.

CONCLUSIONS

This study demonstrates that MHTi + r has more substantial protective effects on reducing ischemia/reperfusion injury than MHTi. It may inhibit post-ischemic hyperperfusion and delayed or sustained hypoperfusion in ischemic perifocal regions, and reduce brain blood barrier disruption in the cortex region.

Immunity in chimpanzees chronically infected with hepatitis C virus: role of minor quasispecies in reinfection

We have previously reported that chimpanzees chronically infected with hepatitis C virus (HCV) could be reinfected, even with the original infecting strain. In this study we tested the hypothesis that this might reflect the presence of minor quasispecies to which there was little or no immunity. To evaluate this hypothesis, we sequenced multiple clones taken at intervals after primary infection and rechallenge from four chronically infected chimpanzees. The inoculum used in these studies (HCV-H, genotype 1a) revealed 17 separate variants among 46 clones sequenced. Following challenge, each of the four challenged animals showed marked alterations of their quasispecies distribution. The new variants, which appeared 1 to 6 weeks after challenge, were either identical to or closely resembled variants present in the challenge inoculum. These results, paralleled by an increase in viremia in some of the challenged animals, suggest that quasispecies in the challenge inoculum were responsible for signs of reinfection and that there was little immunity. However, the newly emerged quasispecies completely took over infection in only one animal. In the remaining three chimpanzees the prechallenge quasispecies were able to persist. The natural evolution of infection within chimpanzees resulted in variants able to compete with the inoculum variants. Whether through reexposure or the natural progression of infection, newly emerged quasispecies are likely to play a role in the pathogenesis of chronic HCV infection.

[Free jejunal grafts for reconstruction of pharynx and cervical esophasgus]

Eleven patients with hypopharyngeal carcinoma were treated surgically and the pharynx and cervical esophagus were reconstructed with free jejunal grafts through the technique of microvascular anastomosis. The microvascular anastomosis were all successful and the patients all survived the operations. The operations were performed at one time with only a few complications. There were 2 cases of pharyngeal fistula and 1 case of bleeding from the anastomotic site. The patients could eat by their mouths and swallow very well just 15 days after the operation. The 3-year suvival rate was 36%. The main causes of death were the recurrence and the metastasis to the cervical lymph nodes. We came to the conclusion that the operation is safe with high success rate and no mortality during operation, and it is less injurious than the gastropharyngeal anastomosis. The key point of the operation is the surgeon's mastery of the microvascular anastomosis technique.

[Genetic polymorphisms of FABP2 and F13A1 loci in Han population]

OBJECTIVE

To find more STR loci usable in forensic medicine and understand the distribution of the genetic polymorphisms of two STR loci FABP2 and F13A1 in the Han population in Chengdu.

METHODS

EDTA-blood specimens were collected from 115 healthy unrelated Han individuals in Chengdu, DNA was extracted using Chelex method. The DNA samples were amplified by PCR technique, and the PAGE horizontal electrophoresis was used for typing of the PCR products.

RESULTS

The allele frequencies were FABP2*1:0.513,FABP2*2:0.096, FABP2*3:0.330, FABP2*4:0.052, FABP2*5:0.009, and 10 genotypes were observed in 115 individuals for FABP2; while for F13A1, the allele frequencies were F13A1*1:0.128, F13A1*2: 0.053, F13A1*3:0.288, F13A1*4:0.527, F13A1*5:0.004 and 10 genotypes were observed in 113 individuals. The result of test for Hardy-Weinberg equilibrium showed that the genotype distribution observed at FABP2 locus was correspondent with the expected.

CONCLUSION

FABP2 may be a useful marker for paternity test or personal indentification of biological stain. On the other hand, more studies need to be done to understand the polymorphism at F13A1 locus in Chinese population because a deviation from Hardy-Weinberg equilibrium has been observed in this Han population.

[Endoscopic variceal ligation combined with partial splenic embolization: preliminary clinical results]

Endoscopic variceal ligation combined with partial splenic embolization (EVL-PSE) was performed in a group of 13 patients with esophageal variceal bleeding and hypersplenism due to portal hypertension from January 1997 to March 1998. PSE was performed one to two weeks before or one week after initial EVL, and a range of 30% to 60% of the splenic parenchyma was embolized. Repeated EVL was performed at two week intervals until the varices were eradicated. Active bleeding in the nine patients was successfully controlled and all the varices of the 13 patients were eradicated after EVL-PSE. Eradication of the varices required two to five(mean 3.1) EVL sessions, follow-up ranging from 2 to 16 months(mean 6.9 months). In all but one case, no rebleeding occurred. All patients after PSE showed a good response on peripheral blood cell count and reduction of splenomegaly. No major complication or death related to the combination therapy was observed. Preliminary results in this study show that this combination therapy may result in more rapid eradication of the varices and reduce rebleeding after endoscopic variceal ligation. However, more data and studies may be necessary for further evaluation.

[Primary study of bacterial adhesion of prosthetic valve materials]

The adhesion of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans to Dacron and pyrolite carbon was measured in vitro with plate counting. The experimental result showed: the bacterials used in the experiment have adhesion to prosthetic valve materials; the bacterials have stronger adhesion to Dacron than to Pyrolite carbon; the bacterial adhesive capacity is significantly different and is affected by mechanical and chemical nature of biomaterials; Staphylococcur aureus has the strongest adhesion to Dacron, and Pseudomonas aeruginosa has the strongest adhesion to pyrolite carbon in all bacterials.

[Studies on the analgesic and antiinflammatory action of radix Linderae extract]

Both of aqueous extract and alconol extract of Radix Linderae at a dose 5 g/kg and 10 g/kg could length obviously pain threshold in mice in hot plate test. The samples at a dose 20 g/kg could inhibit significantly the writhing frequency induced by potassium antimony tartate in mice, also antagonize the swelling of ear induced by inflammatory agent and decrease the swelling rate. The component further isolated from the plant could antagonize the swelling of rat toes induced by carrageenin.

A calcium-metalloribozyme with autodecapping and pyrophosphatase activities

A previously-isolated ribozyme with capping activity has self-decapping activity, here characterized alongside its additional, somewhat parallel, pyrophosphatase reaction. Decapping is 10-50 times slower than the pyrophosphatase activity, depending on pH. The RNA accelerates pyrophosphate release 170 000 times over a control composed of randomized pppRNA, and 5' capped RNA accelerates decapping 1000-fold over random capped RNA. Triphosphate-linked G(5')pppRNA also supports an unusual cap-exchange reaction, exchanging its cap with guanosine 5'-tetraphosphate to form pentaphosphate-linked G(5')pppppRNA. GDP, a capping reactant for the RNA, appears to suppress both decapping and pyrophosphatase activities. Autodecapping and pyrophosphatase activities have in common an unusual divalent metal ion requirement for Ca2+ or less effectively Mn2+, and both are active over a broad pH range of 4.5-9. 0. These characteristics resemble the capping activity of the same RNA. Kinetic analysis reveals a well-defined Ca2+-RNA complex, and Mg2+ and Sr2+ act as competitive inhibitors of Ca2+. A strong Ca2+-binding site is suggested by a low KM of 40-60 microM at pH >/= 7.0. The role of Ca2+ in these reactions can be surmized from literature data on reactivity of nucleotide phosphates. Pyrophosphatase, capping, and decapping activities of isolate 6 RNA are apparently carried out by a single reaction center, whose rate of reaction with all nucleophiles sums to a constant total rate. This suggests a universal rate-limiting step. Versatile activation of alpha-phosphate by this reaction center raises the possibility of combinatorial ribozymes.

[Repair of long segment bone defect of femur by free juxtaposed bilateral fibulae autograft]

There were several methods, such as free single and folded fibulae autograft, composed tissue autograft, however, it is still very difficult to repair long segment bone defect. In December 1995, we used free juxtaposed bilateral fibulae autograft to repair an 8 cm of femoral bone defect in a 4 years old child in success. The key procedure is to strip a portion of the neighboring periosteal sleeve of juxtaposed fibulae to make bare of the opposite sides of the bone shafts, suture the opposite periosteal sleeves, keep the nutrient arteries, and reconstruct the blood circulation of both fibular by anastomosis of the distal ends of one fibular artery and vein to the proximal ends of the other fibular artery and vein, and anastomosis of the proximal ends of the fibular artery and vein to lateral circumflex artery and vein. After 22 months follow up, the two shafts of juxtaposed fibulae fused into one new bone shaft. The diameter of the new bone shaft was nearly the same as the diameter of the femur. There was only one medullary cavity, and it connected to the medullary cavity of femur. This method also cold be used to repair other long segment bone defect.

Interaction of the delta-endotoxin CytA from Bacillus thuringiensis var. israelensis with lipid membranes

We investigated the binding of CytA, a cytolytic delta-endotoxin from Bacillus thuringiensis var. israelensis, to small unilamellar lipid vesicles (SUV) and the accompanying changes in the overall CytA conformation. From the titration of tryptophan fluorescence with SUV, we determined the apparent association constants of 3500 M-1 and 11000 M-1 for the protoxin CytA27 and the proteolytically activated toxin CytA24, respectively. Inclusion of a negatively charged lipid or a positively charged lipid analog in the membrane did not affect the binding parameters, which suggests that membrane binding is not driven by electrostatic interactions. A decrease in the intensity of the CytA tryptophan fluorescence upon interaction with lipids and the absence of a blue shift in remaining fluorescence indicate that the tryptophan-containing regions of the protein do not significantly penetrate into the hydrophobic core of the lipid bilayer. This finding was corroborated by the lack of additional quenching by brominated or spin-labeled lipids, irrespective of the location of the quenching moiety in the depth of the bilayer. However, the interaction with lipids decreases quenching with the soluble quenchers acrylamide and KI, and the remaining fluorescence is blue-shifted. The observed decrease in fluorescence anisotropy upon membrane binding is not consistent with simple immobilization of CytA on the surface of SUV. We showed by FTIR spectroscopy and differential scanning calorimetry (DSC) that binding to the membrane causes a significant loosening of the protein structure. This is consistent with the fluorescence quenching and anisotropy data. Our experiments provide evidence against CytA's substantially penetrating the lipid bilayer and creating well-defined proteinaceous channels.

[Implantation of allogenic osteoblast combined with calcium phosphate composites]

The aim of this experiment was to study the osteogenesis in vivo of allogenic osteoblast combined culture with calcium phosphate composites. The osteoblasts were obtained by enzymatic digestion of periosteum from fibula subcultured to 13 generations, the cells were combined culture with hydroxyapatite and biphasic calcium phosphate. Subseguently, the composite was implanted into rabbits subcutaneously or intramuscularly. The blank material was implanted in the contralateral side as control. Four weeks later, all animals were sacrificed. All the implants were examined by gross observation, histological examination and EDXA. The results showed: 1. obvious ingrowth of connective tissue with very little inflammatory reaction; 2. new bone formation in the composites with deposit of Ca and P on the surface of osteoblast, but none in the blank materials; 3. no significant difference of new bone formation between the different sites of implantation or different materials, but those implanted intramuscularly had lamellae form of new bone while those implanted subcutaneously had only mineralization of extracellular matrix. The conclusion were: 1. the composites are biocompatible with prior osteogenesis property; 2. periosteal-derived allogenic osteoblasts obatined by enzymatic digestion could survive following implantation with bioactivity; 3. rich blood supply might be advantageous to new bone formation and its maturation.

Versatile 5' phosphoryl coupling of small and large molecules to an RNA

A Ca2+-requiring catalytic RNA is shown to create 5' phosphate-phosphate linkages with all nucleotides and coenzymes including CoA, nicotinamide adenine dinucleotide phosphate, thiamine phosphate, thiamine pyrophosphate, and flavin mononucleotide. In addition to these small molecules, macromolecules such as RNAs with 5'-diphosphates, and nonnucleotide molecules like Nepsilon-phosphate arginine and 6-phosphate gluconic acid also react. That is, the self-capping RNA isolate 6 is an apparently universal 5' phosphate-linker, reacting with any nucleophile containing an unblocked phosphate. These RNA reactions demonstrate a unique RNA catalytic capability and imply versatile and specific posttranscriptional RNA modification by RNA catalysis.