Study of hepatic function matching between banna minipig inbred and humans

As a unique inbred pig Banna minipig inbred (BMI) is potentially suitable for pig-to-human xenotransplantation due to its clear genetic background and minor interindividual differences. Previous studies of BMI have focused on immunological barriers between BMI and humans. However, a comparison of liver function between donor animals and humans is an essential premise for successful xenotransplantation. In this study, we investigated routine hepatic functions, protein electrophoresis, and drug metabolism to compare capacity of liver synthesis, metabolism, and drainage between BMI and humans. The results showed no significant differences in the concentrations of albumin and globulin synthesized in the liver (alpha1, alpha2, and beta-globulin). Serum enzyme activities in BMI were higher than those in humans, and levels of total bilirubin and direct-reacting bilirubin of BMI were lower than those of humans. In BMI, the clearance of antipyrine, a widely used model drug to study hepatic drug metabolism, was 16 times greater than that by humans, with a mean residual time of antipyrine in BMI, one-tenth of that in human. These findings suggested that BMI livers are similar to humans in albumin and alpha, beta-globulin synthesis, but stronger in bilirubin elimination, enzyme activity, and drug metabolism. BMI livers may have stronger functions compared with those of humans. No incompatibility was identified in hepatic function between BMI and humans.

Activation of human coagulation system by liver-derived clotting factors of banna minipig inbred line

The liver synthesizes most of the coagulation factors that play a major role in arresting hemorrhage. Matching hepatic coagulation factors is an important premise in successful xenotransplantation. As a unique inbred pig, the Banna minipig inbred (BMI) animals have a huge potential value for pig-to-human xenotransplantation, due to its clear genetic background and tiny interindividual differences. Whether the coagulation factors synthesized by porcine liver can trigger human clotting pathways has not been reported. This study focused on the activities of BMI coagulant factors synthesized exclusively by the liver to activate human clotting pathways. In these experiments we prepared coagulant factors II, V, VII, X, and XII synthesized exclusively by liver from BMI and humans. The factors were used in common correction tests, added to the corresponding factor-deficient human plasma to determine prothrombin times or activated partial thromboplastin time, thereby calculating BMI and human coagulant factor activities. BMI clotting factors XII, VII, and X triggered human intrinsic, extrinsic, and common pathways, respectively. BMI clotting factors II, V, VII, X, and XII activities were 3.2-, 3.7-, 4.7-, 2.9-, and 4.5-fold as potent as those from humans.

Study of renal function matching between banna minipig inbred line and human

Pigs have been thought to be ideal candidates for xenotransplant donors. However besides the immunological barrier, physiological and pharmacokinetic comparabilities of kidney function between donor animals and humans are important factors for successful xenotransplantation. As a unique large inbred animal, Banna Minipig Inbred (BMI) has been reported to be a potential large animal suitable for xenotransplantation. However, its physical and pharmacokinetic compatibilities with humans have not been documented. The purpose of this investigation was to measure renal routine function, glomerular filtration rate (GFR), renal blood flow (ERPF), and drug metabolism to evaluate comparability to humans. The results suggested that the renal function of BMI was similar to that of humans to eliminate nonprotein nitrogenous end products of metabolism. Pharmacokinetics of p-aminohippurate (PAH) and inulin--the most widely used methods to assess ERPF and GFR--showed that BMI showed lower values than humans for GFR, but similar function to humans in ERPF. The pharmacokinetics of cefazolin; a widely used model drug to study kidney drug metabolizing capacity, showed greater overall renal drug elimination of BMI than of humans. These results suggested that BMI did show comparable data to human renal function.

Comparison of methods for the determination of K(L)aO2 for respirometric measurements

The mass transfer coefficient for oxygen in water (K(L)aO2) is an important parameter for respirometric studies. But determination of K(L)aO2 in process conditions is not straightforward, In this paper, two distinct procedures for determining K(L)aO2 in process conditions are outlined and tested. The off-gas method relies on a gas mass balance over a bioreactor while the non-steady state methods rely on analysing DO recovery after perturbation. Various means for inducing perturbation are tested and compared. K(L)aO2 values for a bioreactor are determined by the listed methods. It was found that the off-gas method resulted in the highest K(L)aO2 for the given reactor, while the non-steady state method, whereby perturbation is caused by exogenous activity on acetate, resulted in the lowest K(L)aO2. It is shown that the gas mass balancing technique is robust to unexpected exogenous activity (caused by for example, the oxidation of storage polymers formed or nitrite accumulated), while the non-steady state methods that involve inducing perturbations by exogenous activity appear susceptible to such continued exogenous activity in the DO recovery period.

Capillary electrophoresis-electrospray mass spectrometry for the characterization of high-mannose-type N-glycosylation and differential oxidation in glycoproteins by charge reversal and protease/glycosidase digestion

The characterization of high-mannose-type N-glycosylation by capillary electrophoresis-electrospray mass spectrometry (CE-ESI MS) was described. In addition to the use of a cationic noncovalent capillary coating, strong acidic buffer, and charge reversal to increase the glycoform resolving power, N-glycosidase F (PNGase F) combined with a basic protease and alpha-mannosidase combined with an acidic protease were used to analyze the high-mannose-type N-glycosylation in ribonuclease B (RNase B) and in a novel C-type lectin from the venom of Trimeresurus stejnegeri (TSL). The structures of oligosaccharide, glycosylation sites, and glycoform distributions were determined simultaneously, and the differential oxidation of Met residues in glycopeptides obtained from TSL protease digestion was also characterized successfully by CE-MS/MS. The results showed that the oligosaccharide attached to RNase B has a structure of GlcNAc2Man5 approximately 9, and that attached to TSL has a structure of GlcNAc2Min5 approximately 8. The glycoform distributions in these glycoproteins are quite different, with the GlcNAc2Man5 type predominant in RNase B, and the GlcNAc2Man8 type, in TSL This method may be useful not only for the characterization of glycosylation sites and glycan structures, but also for the determination of the relative abundance of individual glycoforms.

[The prevalence of beta-thalassemia heterozygotes compound alpha-thalassemia in Guangdong district]

OBJECTIVE

To investigate the prevalence of beta-thalassemia (beta-thal) heterozygotes compound alpha-thal in Guangdong area.

METHODS

alpha-thal 1 genes were amplified in 500 beta-thal carriers diagnosed by reverse dot blotting (RDB) using gap-PCR method, alpha-thal 2 genes were detected in 400 of the 500 beta-thal carriers using Southern blotting with alpha-globin DNA probe and restrict endonuclease zymogram analytical method.

RESULTS

Forty three alpha-thal-1(alpha alpha/- -SEA) cases were identified in the 500 beta-thal traits, and 26 alpha-thal 2 including 17 rightward deletion (alpha alpha/- alpha 3.7) and 9 leftward deletion(alpha alpha/-alpha 4.2) cases were identified in the 400 beta-thal traits.

CONCLUSION

The prevalence of beta-thal heterozygote carrying alpha-thal-1 gene was 8.6% and that of beta-thal heterozygote carrying alpha-thal-2 gene was 6.5% (4.2% rightward deletion and 2.2% leftward deletion).

Initiation of polyoma virus origin-dependent DNA replication through STAT5 activation by human granulocyte-macrophage colony-stimulating factor

Several lines of evidence indicate that transcriptional activation is coupled with DNA replication initiation, but the nature of initiation of DNA replication in mammalian cells is unclear. Polyoma virus replicon is an excellent system to analyze the initiation of DNA replication in murine cells because its replication requires an enhancer, and all components of replication machinery, except for DNA helicase large T antigen, are supplied by host cells. This system was used to examine the role of signal transducer and activator of transcription (STAT5) in replication initiation of polyoma replicon in the mouse lymphoid cell line BA/F3. The plasmid with tandem repeats of consensus STAT5 binding sites followed by polyoma replication origin was replicated by stimulation with human granulocyte-macrophage colony-stimulating factor (hGM-CSF) in the presence of polyoma large T antigen in BA/F3 cells. Mutation analysis of the hGM-CSF receptor beta subunit revealed that only the box1 region is essential, and the C-terminal tyrosine residues are dispensable for the activity. Addition of the tyrosine kinase inhibitor genistein suppressed this replication without affecting transcriptional activation of STAT5. Because deletion analysis of STAT5 indicates the importance of the C-terminal transcriptional activation domain of STAT5 for the initiation of replication, the role of this region in the activation of replication was examined with a GAL4-STAT5 fusion protein. GAL4-STAT5 activated replication of the plasmid containing tandem repeats of GAL4 binding sites and polyoma replication origin in BA/F3 cells. Mutation analysis of GAL4-STAT5 indicated that multiple serine residues coordinately have a role in activating replication. This is the first direct evidence indicating the potential involvement of STAT5 in replication.

Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry

In the previous study, the proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 were separated by high resolution two-dimensional electrophoresis (2-DE). Image analysis revealed that 99 protein spots showed quantitative and qualitative variations that were significant (P < 0.01) and reproducible. Here we report the identification results of some of these protein spots. Protein spots excised from 2-D gels were subjected to in-gel digestion with trypsin, and the resulting peptides were measured by microbore high performance liquid chromatography - ion trap - mass spectrometry (LC-IT-MS) to obtain the tandem mass (MS/MS) spectra. Twelve protein spots were identified with high confidence using SEQUEST with uninterpreted MS/MS raw data. Besides inosine-5'-monophosphate dehydrogenase 2, heat shock 27 kDa protein, calreticulin and calmodulin, whose expression was elevated in hepatoma cells, glutathione-S-transferase P was identified from hepatoma cells in which its level was 18-fold higher compared to human liver cells. Two spots were identified as the homologs of reticulocalbin for the first time in hepatoma cells and their expression increased compared to liver cells. However, tubulin beta-1 chain and natural killer cell enhancing factor B were downregulated in hepatoma cells. A tumor suppressing serpin, maspin precursor, was identified from one spot whose quantity was much higher in the normal liver cell line. More interestingly, epidermal fatty acid-binding protein (E-FABP) and fatty acid-binding protein, adipocyte-type (A-FABP), were detected in liver cells but not in hepatoma cells. The functional implication of the identified proteins was discussed.

Determination of the disulfide bond pattern of a novel C-type lectin from snake venom by mass spectrometry

The disulfide bond pattern of Trimeresurus stejnegeri lectin (TSL), a new member of the C-type lectin family, was determined by mass spectrometry. Four intrachain disulfide bonds of TSL, Cys(3)-Cys(14), Cys(31)-Cys(131), Cys(38)-Cys(133) and Cys(106)-Cys(123), and two interchain linkages, Cys(2)-Cys(2) and Cys(86)-Cys(86), were determined. Three strategies were used in this work. One intrachain (Cys(106)-Cys(123)) and one interchain (Cys(86)-Cys(86)) disulfide linkages were detected by standard MS methods. The disulfide bonds Cys(2)-Cys(2) and Cys(3)-Cys(14) were analyzed using a modified partial reduction procedure and MS/MS. The last two disulfide bonds were characterized by a MS/MS/MS technique. The strategies developed in this work could be applied more generally to detection of disulfide bond patterns.

Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry

In the previous study, the proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 were separated by high resolution two-dimensional electrophoresis (2-DE). Image analysis revealed that 99 protein spots showed quantitative and qualitative variations that were significant (P < 0.01) and reproducible. Here we report the identification results of some of these protein spots. Protein spots excised from 2-D gels were subjected to in-gel digestion with trypsin, and the resulting peptides were measured by microbore high performance liquid chromatography - ion trap - mass spectrometry (LC-IT-MS) to obtain the tandem mass (MS/MS) spectra. Twelve protein spots were identified with high confidence using SEQUEST with uninterpreted MS/MS raw data. Besides inosine-5'-monophosphate dehydrogenase 2, heat shock 27 kDa protein, calreticulin and calmodulin, whose expression was elevated in hepatoma cells, glutathione-S-transferase P was identified from hepatoma cells in which its level was 18-fold higher compared to human liver cells. Two spots were identified as the homologs of reticulocalbin for the first time in hepatoma cells and their expression increased compared to liver cells. However, tubulin beta-1 chain and natural killer cell enhancing factor B were downregulated in hepatoma cells. A tumor suppressing serpin, maspin precursor, was identified from one spot whose quantity was much higher in the normal liver cell line. More interestingly, epidermal fatty acid-binding protein (E-FABP) and fatty acid-binding protein, adipocyte-type (A-FABP), were detected in liver cells but not in hepatoma cells. The functional implication of the identified proteins was discussed.

[The St14 (DXS 52) VNTR in a Guangdong Han population and detection of hemophilia A carriers]

OBJECTIVE

To investigate the genetic polymorphism of the St14 (DXS 52) variable number tandem repeat (VNTR) in normal individuals in Guangdong, and to evaluate the efficacy of this marker for the gene diagnosis of hemophilia A.

METHODS

125 unrelated healthy individuals (male 21, female 104) and 4 hemophilia A families were detected using amplified-fragment-length polymorphism (Amp-FLP).

RESULTS

11 allelic fragments ranging from 700 to 1,810 bp in size and 7 different genotypes in males, 17 different genotypes in females were observed, respectively. The allele frequencies were 0.0044 to 0.4803. The polymorphism information contents (PIC) was 0.7335, and the heterozygosity was 0.432. Four families with hemophilia A were analyzed and 2 of them were informative for linkage analysis. In one family, 2 females were determined to be normal individuals, not carriers, one female carrier was detected in the other family.

CONCLUSION

St14 (DXS 52) was a useful polymorphism marker for carrier detection of hemophilia A in southern Chinese population, and it was different from those in Caucasian.

Expression of isolated C-type carbohydrate recognition domains

A galactose-binding lectin from the venom of the snake Trimeresurus stejnegeri consists of isolated carbohydrate recognition domains, belonging to group VII of the C-type animal lectins. As a first step toward determining the tertiary structure of the galactose-specific lectin, we produced the lectin in Escherichia coli. By in vitro refolding and affinity chromatography, modest amounts (8 mg/liter) of active recombinant proteins were obtained. The recombinant protein was homogeneous, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. Its amino acid sequence without the initiated methionine at the N-terminus was also characterized by mass spectrometry. The data of hemagglutination and enzyme-linked lectin binding assays demonstrated that the recombinant lectin showed similar sugar-binding activity as the native protein. In addition, fluorescence spectroscopy and circular dichroism also showed obviously their structural similarity.

[Correction of dento-maxillofacial deformities by using both of orthodontics and orthognathic surgery]

OBJECTIVE

To study the clinical results and stability after correction of dento-maxillofacial deformities by using both of orthodontics and orthognathic surgery.

METHODS

A group of 45 patients with dento-maxillofacial deformities were corrected by preoperative orthodontics-orthognathic surgery-postoperative orthodontics procedure. As a control, another group of 64 patients with the deformities were corrected by orthognathic surgery only. The facial appearance, occlusion and stability of two groups after correction were investigated and compared.

RESULTS

In orthodontics and orthognathic surgery group, 62.2% of patients declared that their mastication were improved. Relapse rate of deformities was 4.4%. In orthognathic surgery group, 42.2% of patients declared that their mastication were improved. Relapse rate of deformities was 9.4%.

CONCLUSIONS

Using both of orthodontics and orthognathic surgery to correct dento-maxillofacial deformities is a good approach to improve results of correction, keep balance of occlusion and reduce the relapse of the deformities.

[Artery denuded model and effects of three kinds of antisense c-myc RNA]

OBJECTIVE

To investigate the effects of antisense c-myc on injured vascular wall.

METHODS

Three recombinant retroviral expression vectors, aM1, aM2 and aM3, which loading the reverse fragment of exon1, 2 and 3 respectively, were transferred into denuded rabbit femoral artery wall and were assayed 21 days after operation.

RESULTS

(1) The regions of rabbit femoral artery were not only convenient for injury control, drug giving and material drawing, but also gave a neointimal area to media area vatio of 1.37:1. Their intensity and area of c-myc expression in media increased to 1.8 and 1.5 fold of normal value. (2) c-myc expression in aM2, aM3 and aM1 was reduced by 37.5%, 20.8%, and 17.8% with media intensity, 71.5%, 57.2%, and 61.6% with media area and 31.3%, 20.8%, and 17.8% with neointimal intensity respectively. (3) Neointimal area/media area of aM2 group reduced by 72.6%, aM3 group reduced by 35.2%, aM1 group had no significant difference comparing with control group. (4) Proliferating cellular nuclear antigen (PCNA) in the intimal and media of the three antisense transferred groups was enhanced with their expressive intensities, but reduced with expressive areas significantly. (5) With the declining of neointimal area/media area, alpha-SM actin expression in the intimal and media of the three antisense transferred groups was significantly increased (aM2 > aM3 > aM1).

CONCLUSION

(1) Rabbit femoral artery denuded model is a satisfactory animal model. (2) Antisense c-myc transferring can reduce or resist the c-myc increase in injured artery wall, resist neointimal hyperplasia and smooth muscle cells dedifferentiation,especially c-myc exon 2 antisense RNA vector aM2.

[Detection of R277Q mutation of SRD5alpha2 gene by amplification refractory mutation system]

OBJECTIVE

To set up a simple method for identifying the mutation of R227Q of SRD5alpha2 gene which is one of the most common mutations in congenital hypospadias in China.

METHODS

The amplification refractory mutation system(ARMS) was employed in detecting the SRD5alpha2 gene R227Q mutation in congenital hypospadias confirmed by PCR-SSCP and DNA sequencing.

RESULTS

The ARMS was successfully applied to the detection of the R227Q mutation of SRD5alpha2 gene. Three out of 23 congenital hypospadias were positive for R227Q mutation. The mutations determined by ARMS were in full agreement with those obtained by the DNA sequencing.

CONCLUSION

This is a simple, rapid and accurate method. It can be used for detecting the SRD5alpha2 gene R227Q mutation in congenital hypospadias and male pseudohermaphroditism.

Characterization and analysis of a novel glycoprotein from snake venom using liquid chromatography-electrospray mass spectrometry and Edman degradation

An N-linked glycosylation in a novel C-lectin protein from snake venom was observed by Edman degradation and liquid chromatography-electrospray mass spectrometry. The peptides obtained by trypsin cleavage were analyzed to confirm the amino acid sequence and Asn5 was found to be the N-glycosylation site. The result was further confirmed by N-glycosidase digestion. In addition, the protein and tryptic peptides with and without glycan chain were characterized by mass spectrometry according to the mass difference. The glycopeptide obtained from proteolytic digestion was analyzed and the glycoforms were identified as high-mannose type by tandem MS coupled with alpha-mannosidase digestion. An oxidized Met residue was detected and located in the protein by mass spectrometry.

Analysis of 8-aminonaphthalene-1,3,6-trisulfonate-derivatized oligosaccharides by capillary electrophoresis-electrospray ionization quadrupole ion trap mass spectrometry

Dextran was partially hydrolyzed with 0.1 mol/l HCl and the hydrolysate was derivatized with 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) by reductive amination. The derivatized-oligosaccharide mixture was separated by capillary electrophoresis (CE) in a buffer of 1% HAc-NH4OH, pH 3.4, and the separated components were detected on-line by electrospray ionization quadrupole ion trap mass spectrometry (ESI-QIT-MS) in the negative ion mode. A mass accuracy lower than 0.01% could be achieved and as low as 1.6 pmol of detxran octaose could be detected. ANTS-derivatized dextran oligosaccharide with a degree of polymerization (DP) lower than 6 produced both [M-H]- and [M-2H]2- ions, whereas those with a DP of 6 or higher than 6 produced only [M-2H]2- ion. As 1< or =DP< or =6, the percentage of [M-2H]2- ion in the total ions of [M-H]- and [M-2H]2- was found to be a linear function of the logarithmic DP. Molecular mass determination with ESI-QIT-MS strengthens the power of CE analysis of oligosaccharides.

Analysis of recombinant and modified proteins by capillary zone electrophoresis coupled with electrospray ionization tandem mass spectrometry

A method for rapid characterization of recombinant and modified proteins with known sequences is described. The analytical system consists of a capillary zone electrophoresis (CZE) instrument coupled to an electrospray ionization ion trap tandem mass spectrometer via a sheath-flow interface. Following the procedure consists of proteolytic fragmentation, CZE peptide separation, tandem mass spectrometry (MS-MS) analysis of separated peptides, sequence database search and monitoring of the specific peptides, C 125 S mutated interleukin 2 (S-125-IL2) and bovine beta-casein were characterized as a model of recombinant protein and naturally modified protein, respectively. A tryptic peptide mixture derived from the synthetic salmon calcitonin (s-CT) was also analyzed to test the performance of the system. Although a conventional sheath-flow interface with much higher flow-rate compared to the microspray interface and nanospray interface was used, the proteins were identified at the low picomole level.

[Analysis of prenatal diagnosis for 120 cases of beta-thalassemia]

OBJECTIVE

To analyse the results of prenatal gene diagnosis of beta-thalassemia.

METHODS

By using the reverse dot blot method with an allele specific oligonucleotide probe(ASO/DRB).

RESULTS

In 120 cases of prenatal gene diagnosis, there are 30 of normal fetal; 63 of beta-thalassemia heterozygotes; 26 of beta-thalassemia homozygotes or dual heterozygotes; one of no diagnosis because the beta mutated gene can not be detected in one side of the parent.

CONCLUSIONS

Acording to the follow-up studies, the babies unconcordance with prenatal diagnosis have not been found, the accuracy rate being 100%. Amniotic fluid specimen of the middle stage of pregnancy is the best for detection.

[Detection of alpha-thalassemia 1 gene among 142 beta-thalassemia gene carriers]

OBJECTIVE

To investigate the coincidental rate of double heterozygous state of beta-thalassemia and alpha-thalassemia 1 in Guangdong area.

METHODS

One handred and forty-two DNA samples with beta-thalassemia trait were amplified by polymerase chain reaction(PCR) to detect alpha-thalassemia 1 gene. The positive cases were further detected by mutant primer PCR or by reverse dot blot hybridization (ASO/RDB) to confirm their beta-thalassmia mutations.

RESULTS

Thirteen cases (9.15%) were identified to combine with alpha-thalassemia 1 gene. The mutant loci of beta-globin gene in these cases were that 5 were in CD 41-42 (-TCTT), 3 in IVS-2-654(C-->T), 2 in CD 17 (A-->T) and 3 in CD 71-72 (+A), CD 43(G-->T) and -28 (A-->G), respectively.

CONCLUSIONS

The occurrence of this dual heterozygotes among beta-thalassemia trait is relatively frequent and it should be paid much attention to in genetic counselling and prenatal diagnosis of thalassemia in this area.

[Genetic diagnosis of alpha and beta thalassemia dual heterozygote]

OBJECTIVE

To perform genetic diagnosis of alpha and beta thalassemia dual heterozygotes.

METHODS

PCR and beta-thalassemia allele specific oligonucleotide probe/reverse dot blot(ASO/RDB) techniques were used.

RESULTS

Six cases of suspected alpha-thalassemia-1 and beta-thalassemia dual heterozygotes were found in genetic counseling and prenatal diagnosis. On genetic diagnosis, they were all Southeast Asia(SEA) type of alpha-thalassemia-1 and beta-thalassemia (--SEA/alpha alpha, beta T/beta A) dual heterozygotes. Out of them, 3 cases were alpha-thalassemia-1 and beta 41-42 (-TCTT), 2 were alpha-thalassemia-1 and beta-28(A-->T) and 1 was alpha-thalassemia-1 and beta IVS-II-654(C-->T) double heterozygotes.

CONCLUSION

The detection of thalassemia dual heterozygotes facilitates the prenatal diagnosis with more precision.

[Application of antigen linked with chemicals on nitrate cellulose membrane for dot-enzyme immunoassay]

HCMV-IgG in sera of pregnant women was detected by means of dot-enzyme immunoassay (DEIA), in which antigen was cross-linked on nitrate cellulose membrane through chemical reagent. The results showed better repetition by DEIA, compared with ELISA, and no significant differences were noted between the two methods in the rates of detecting HCMV-IgG in positive, weak positive and negative sera. The rate of agreement was 93.2%. In examining the sera which had been examined by ELISA for three times with the same, results the sensitivity, specificity, index and efficiency of diagnosis by DEIA were 100%, 96.6%, 196.6% and 98.7% respectively. Since this method is convenient, fast, of good repetition, economical and its diagnosis index meets the application criterion, it is more suitable for clinical laboratories.

[Application of PCR-SSCP to rapid genetic diagnosis of adult polycystic kidney disease]

OBJECTIVE

To explore a rapid and easy-to-do linkage analysis in families with adult polycystic kidney disease(APKD).

METHODS

The polymorphism of SM7, a SRS which lies proximal to PKD1, among Chinese people was analysed using PCR, PAGE and silver staining. SM7-SSLP linkage analyses were performed in two APKD families and the results were compared with these of 3'HVR/Pvu II linkage analyses in the same families.

RESULTS

Seven kinds of SM7 alleles were observed in the 67 unrelated Chinese people. The heterozygosity was 52.5% and PIC 0.62. The most common allele was Y9. The result was close to that of Harris's report, showing that there is no marked difference in the polymorphism of SM7 between Chinese and Caucasian. The results of SM7-SSLP linkage analyses in the two APKD families consisted with the results of 3'HVR/Pvu II linkage analyses though in one family the information provided by SM7 was less than 3'HVR.

CONCLUSION

The polymorphism of SM7 locus is high in Chinese and SM7 can be used in linkage analysis as a valuable marker. SSLP linkage analysis proved to be avery useful way for rapid genetic diagnosis of APKD providing that a highly polymorphic marker is used, and the result can be analysed easily.

Exon-by-exon screening for RB germline mutations using Heteroduplex-SSCP analysis

OBJECTIVE

To disclose the nature of RB1 germline mutations in Chinese and to develop a practical and effective way for mutational screening.

METHODS

Leukocyte DNA was prepared from 8 Chinese patients with hereditary retinoblastoma. PCR combined with nonisotopic heteroduplex-SSCP analysis was used to screen leukocyte DNA for RB1 germline mutations, exon-by-exon, without the use of restriction endonuclease digestion. The mutations were finally identified by sequencing. In order to testify the effectiveness of this method, the same method was used to detect other 17 samples which have been previously analyzed by other methods.

RESULTS

Heterozygous germline mutations were detected in the leukocyte DNA of 6 out of 8 Chinese patients: G del/codon 46, T del/codon 131, CAGAA del/codon 257-258, GCAgta-->GCAgca/donor of exon 16, C-->T/codon 661, and C-->T/codon 787. Heteroduplex-SSCP analysis may detect RB1 germline mutations in 68% (17/25) unselected patients, which is more effective than SSCP(56%) or heteroduplex analysis(64%) alone. The corrected RB1 mutation detection rate may be 80% if the samples were previously analyzed by Southern blotting, which is much higher than those reported on literature.

CONCLUSION

Mutations involving a few base pairs in RB1 gene are common in Chinese. Heteroduplex-SSCP analysis is more useful and effective than SSCP or heteroduplex analysis alone for the rapid screening for unknown mutations.

[Experimental study on bone formation in a denser coral used for repairing cortical defects in dogs]

The present study was designed to investigate a coral skeleton, Favites, which was originated from the reef builders in Hainan island, as a bone substitute. The coral Favites, like porites, is composed of anagonite (CaCO3), but contains less volume of porosity, higher strength and denser construction than Porites. After implanted into cortical bone defects in mandibles and femurs of dogs, skeleton fragment of coral Favites demonstrated good biocompatibility and biodegradability. A resorption of the implant and a simultaneous apposition of new bone was observed. Coral Favites was totally replaced by newly formed bone after a period of time from 6-8 months. Compared to Porites, Favites has a lower rate of resorption and therefore the defects of host bone are repaired completely without any lost of bone volume. The results showed that coral Favites may be used as a bone substitute for the segmental defects of mandibles.