Elevated plasma osteopontin level is predictive of cirrhosis in patients with hepatitis B infection

BACKGROUND

Osteopontin (OPN) was shown to play an important role in the pathogenesis of various inflammatory and fibrotic processes and elevated in fibrotic liver of mouse model. However, the significance of OPN in hepatitis B virus (HBV)-induced liver cirrhosis (LC) remains unclear and is therefore evaluated in this study.

METHODS

Thirty-nine patients with HBV-induced LC, 30 patients with HBV infection but without cirrhosis, 11 patients with HBV-related hepatocellular carcinoma (HCC) and 14 additional healthy controls were enrolled in this study. Plasma levels of OPN were measured with enzyme-linked immunosorbent assay and the relationship between OPN and clinical parameters was evaluated.

RESULTS

When compared to HBV infection group (median 2.16 ng/ml), plasma levels of OPN were significantly increased in cirrhosis (4.52 ng/ml, p < 0.001) and cancer group (13.38 ng/ml, p < 0.001). The OPN level was correlated with the severity of liver damage according to Child-Pugh classification (p = 0.003). It showed at least comparable sensitivity and specificity to predict cirrhosis as aspartate aminotransferase to platelet ratio index, a previously established non-invasive serum marker of cirrhosis.

CONCLUSIONS

These data suggest that OPN could be used to evaluate the existence of LC, as OPN has previously been reported to be increased in the HCC; this unique feature makes OPN a promising candidate for prediction biomarker in the long-time surveillance of patients with HBV infection to evaluate the risk of cirrhosis and cancer.

[Hypoxia induced HIF-1 accumulation and VEGF expression in gastric epithelial mucosa cell: involvement of ERK1/2 and PI3K/Akt]

Hypoxia is a common environmental stress that influences signaling pathways and cells function, which through initiating intracellular signaling pathways and hence leading to the activation of the transcription factor hypoxia-inducible factor-1 (HIF-1). In this study, we initially confirm that hypoxia activates HIF-1alpha protein expression in a time-dependent manner with a maximum reached at 60 min in vitro and 4h in vivo in gastric mucosa epithelial cells. The expression of HIF-1alpha is correlated with the activation of HIF-1 DNA binding and transcriptional activity. Hypoxia dose not affect HIF-1alpha mRNA transcription but regulates HIF-1alpha protein expression through a translation-dependent pathway to regulate protein synthesis. Hypoxia could induce phosphorylation of Akt, MAPK (ERK), and target of p70S6K1. PI3K and MAPK inhibitor, LY294002 and U0126 could inhibit hypoxia-induced HIF-1 and VEGF expression. We also investigated the role of reactive oxygen species (ROS) involved in HIF-1 and VEGF expression Exogenous addition of H2O2 was sufficient to activate Akt and ERK, scavengers of H2O2 significantly inhibited hypoxia-induced Akt and ERK, and subsequent HIF-lax expression and transcriptional activity. In conclusion, our data suggested that hypoxia- PI3K signaling through Akt and ERK kinases regulated ROS-dependent, hypoxia- induced HIF-1 activation and VEGF expression in gastric mucosa epithelial cells.

Deregulated expression of Notch receptors in human hepatocellular carcinoma

BACKGROUND AND AIM

Notch signaling controls cellular differentiation and proliferation. Deregulated expression of Notch receptors is observed in a growing number of malignant tumours, however, the role of Notch signaling in hepatocellular carcinoma is still unknown. To address this, the expression of Notch receptors in human hepatocellular carcinoma was examined in both protein and ribonucleic acid levels.

PATIENTS AND METHODS

Fifty-three hepatocellular carcinoma tissue sections were detected by immunohistochemistry. Three paired fresh surgical hepatocellular carcinoma and adjacent nontumour liver samples were analyzed by Western blot and reverse transcriptase polymerase chain reaction. Immunohistochemistry, Western blot and reverse transcriptase polymerase chain reaction are reliable methods to examine the expression of protein and RNA.

RESULTS

All of the four Notch receptors were expressed in the neoplastic cells of hepatocellular carcinoma tissues with different intensity and extensity. Notch1 and Notch4 were expressed in both cytoplasm and nucleus, and all of the nuclear staining showed up in the cytoplasm-positive cases. Cytoplasmic and nuclear Notch1 was detected in 88.7% (47/53) and 9.4% (5/53) of hepatocellular carcinoma tissues, respectively; positive rates of Notch4 were 67.9% (36/53) in cytoplasm and 52.8% (31/53) in nucleus. Notch2 and Notch3 were only in cytoplasm, with positive rates of 26.4% (14/53) and 52.8% (28/53), respectively. Compared with adjacent nontumour liver, Notch1 (cytoplasmic) and Notch4 (nuclear) were up-regulated (P<0.05, P<0.05), Notch2 was down-regulated (P<0.05), while Notch1 (nuclear), Notch3 and Notch4 (cytoplasmic) showed no difference between hepatocellular carcinoma and adjacent nontumour liver. Western blot and reverse transcriptase polymerase chain reaction analysis showed a consistent result.

CONCLUSION

Our findings indicate that the expression of Notch receptors was deregulated and Notch signaling might be involved in the development of hepatocellular carcinoma.

[Reversal of multidrug resistance of gastric cancer cells by down-regulation of CIAPIN1 with CIAPIN1 siRNA]

The overexpression of a new cytokine-induced apoptosis inhibitor 1 (CIAPIN1) gene has been shown previously to promote a multidrug resistant phenotype in gastric cancer cells through the upregulation of MDR1 and MRP1. In the present study, we constructed the siRNA eukaryotic expression vectors of CIAPIN1 and transfected them into SGC7901/VCR cells to examine whether the down regulation of CIAPIN1 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of CIAPIN1 was dramatically decreased in CIAPIN1 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of CIAPIN1 significantly enhanced the sensitivity of SGC7901/VCR cells to vincristine (VCR), adriamycin (ADR) and etoposide (VP-16), but not to 5-fluorouracil (5-FU) and cisplatin (CDDP). Cell capacity to efflux adriamycin decreased markedly in CIAPIN1 siRNA transfectants, and correlation between CIAPIN1 down regulation and decreased MDR1 transcriptional activity were observed. CIAPIN1 siRNA could significantly down regulate the expression of Bcl-2, and up-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. These observations suggested that the siRNA constructs of CIAPIN1 we obtained could effectively down-regulate the expression of CIAPIN1 and reverse the resistant phenotype of gastric cancer cells. The further study of the biological functions of CIAPIN1 may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible strategies to treat gastric cancer.

Phospho Akt mediates multidrug resistance of gastric cancer cells through regulation of P-gp, Bcl-2 and Bax

Phosphatidylinositol 3-kinase/Akt pathway is an important intracellular pathway that is frequently activated in cancer cells. The role of P-AKT in multidrug resistance of gastric cancer cells and the possible underlying mechanisms are here investigated. Up-regulation of P-AKT expression could confer resistance to both P-glycoprotein-related and P-glycoprotein-non-related drugs on AGS cells, and suppress adriamycin-induced apoptosis, along with decreased accumulation and increased releasing amount of adriamycin. P-AKT could significantly up-regulate the expression of Bcl-2, and down-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. Inhibition of P-AKT expression could partially reverse P-AKT-mediated multidrug resistance and significantly up-regulate P53 expression, and down-regulate the expression of P-glycoprotein and the transcription of the multidrug resistance gene 1. Further studies of the biological functions of P-AKT may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible therapeutical strategies.

Association between hepatitis B virus infection and HLA-DRB1 genotyping in Shaanxi Han patients in northwestern China

Hepatitis B virus (HBV) infection is a major public health problem worldwide. The mechanism of susceptibility to chronic persistent HBV infection is not well clarified, while the outcome of HBV infection mainly depends on the host immune response. Human leukocyte antigen (HLA) class II molecule is an integral component of the immune response on which majority of host genetic studies have concentrated. Many different HLA class II alleles have been demonstrated to play roles in HBV infection. In this study, the association between HBV infection and HLA-DRB1 alleles in Han individuals in northwestern China was studied for the first time. Two hundred and fifty Shaanxi Han individuals were categorized into three different groups: the HBV-infected patient group (n = 108), the spontaneously cleared control group (n = 108) and the unexposed group (n = 34). DRB1*04, DRB1*09, DRB1*12 and DRB1*15 were the most common genotypes in all the groups. The allele frequencies of HLA-DRB1*03 [10.6% of HBV-infected patients vs 3.7% of spontaneously cleared controls, odds ratios (OR) = 3.10, Pc = 0.008, P < 0.05] and HLA-DRB1*07 (17.6% of HBV-infected patients vs 9.3% of spontaneously cleared controls, Pc = 0.016, OR = 2.09, P < 0.05) were markedly higher in the HBV-infected group. But the allele frequencies of HLA-DRB1*15 (6.9% of HBV-infected patients vs 13.4% of spontaneously cleared controls Pc = 0.039, OR = 0.48, P < 0.05) were obviously lower than that of the spontaneously cleared controls. The above data indicate that HLA-DRB1*03 and HLA-DRB1*07 are related to susceptibility to chronic HBV infection, and DRB1*15 is negatively related to persistence to chronic HBV infection among people in northwestern China. Similar results were got for DRB1*03 and 15 alleles between the HBV-infected patients (n = 108) and 46 HBV seronegative spouses of the HBV patients, who were high-risk group for HBV infection. The above results suggest that host HLA class II gene is an important factor in determination of the outcome of HBV infection.

Community-based incidence of acute renal failure

There is limited information about the true incidence of acute renal failure (ARF). Most studies could not quantify disease frequency in the general population as they are hospital-based and confounded by variations in threshold and the rate of hospitalization. Earlier studies relied on diagnostic codes to identify non-dialysis requiring ARF. These underestimated disease incidence since the codes have low sensitivity. Here we quantified the incidence of non-dialysis and dialysis-requiring ARF among members of a large integrated health care delivery system - Kaiser Permanente of Northern California. Non-dialysis requiring ARF was identified using changes in inpatient serum creatinine values. Between 1996 and 2003, the incidence of non-dialysis requiring ARF increased from 322.7 to 522.4 whereas that of dialysis-requiring ARF increased from 19.5 to 29.5 per 100,000 person-years. ARF was more common in men and among the elderly, although those aged 80 years or more were less likely to receive acute dialysis treatment. We conclude that the use of serum creatinine measurements to identify cases of non-dialysis requiring ARF resulted in much higher estimates of disease incidence compared with previous studies. Both dialysis-requiring and non-dialysis requiring ARFs are becoming more common. Our data underscore the public health importance of ARF.

Prognostic significance of osteopontin in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND AND AIMS

Osteopontin (OPN) is known to be associated with metastasis in many types of cancers. Since OPN is a highly phosphorylated and glycosylated protein, the modification after transcription is very important to its function. In hepatocellular carcinoma (HCC), the elevated expression of OPN at mRNA levels and its relationship with metastasis and poorer prognosis of the patients have been reported. However, the prognostic impact of OPN at protein levels on the patients with hepatitis B virus (HBV)-related HCC after hepatectomy is still limited.

PATIENTS AND METHODS

The expression of OPN was examined at protein level by using immunohistochemistry in 72 patients who underwent hepatectomy for HBV-related HCC, and its prognostic significance in disease-free and overall survival of the patients was also analyzed by log-rank test and multivariate Cox regression analyses.

RESULTS

Thirty-nine of 72 (54.17%) HBV-related HCC specimens were positive for OPN with cytoplasmic staining. OPN was highly expressed in the specimens with capsular infiltration compared to those without (P<0.05), and also was significantly related with portal vein invasion (P<0.01) and lymph node invasion (P<0.01). The mean disease-free survival (DFS) was only 13.55+/-14.77 months when the HBV-related HCC specimens highly expressed OPN compared to 36.00+/-18.68 months for those with low expression (P<0.001). The overall survival (OS) of the patients was 18.63+/-17.28 months when the HCC over-expressed OPN compared to 42.59+/-16.85 months for HCC with the low expressed OPN (P<0.001). Multivariate analysis showed that OPN over-expression was the strongest independent adverse prognostic factor for both DFS (P=0.01) and OS (P=0.014).

CONCLUSIONS

OPN over-expression was closely related to capsular infiltration, venous invasion, lymph node metastasis, and also with worse prognosis, suggesting that OPN might be deemed as a useful molecular marker for predicting the prognosis of HCC.

Reversal of multidrug resistance of gastric cancer cells by downregulation of Akt1 with Akt1 siRNA

Phosphatidylinositol 3-kinase/AKT1 pathway was an important intracellular pathway that was frequently activated in cancer cells. In the present study, we constructed the siRNA eukaryotic expression vectors of AKT1 and transfected them into AGS cells to examine whether the down-regulation of AKT1 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of AKT1 was dramatically decreased in AKT1 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of AKT1 could significantly enhance the sensitivity of AGS cells to vincristine, adriamycin, 5-fludrouracil and cisplatin. AKT1 siRNA could significantly down-regulate the expression of Bcl-2, and up-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. These observations suggested that the siRNA constructs of AKT1 we obtained could effectively down-regulate the expression of AKT1 and reverse the resistant phenotype of gastric cancer cells. The further study of the biological functions of AKT1 may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible strategies to treat gastric cancer.

Zinc ribbon domain containing 1 protein: modulator of multidrug resistance, tumorigenesis and cell cycle

Zinc ribbon domain containing 1 (ZNRD1) gene encoding a protein consisting of two zinc ribbon domains was recently cloned from the human HLA locus. So far, ZNRD1 has been found implicated in transcription regulation and might play potential roles in mediating several biological processes, including multidrug resistance, tumorigenesis and cell cycle. This article reviewed these recent findings and provided additional information to support the role of ZNRD1 gene as a novel candidate DNA damage repair related gene.

High frequency occurrence of 1-OPRD variant of PRNP gene in gastric cancer cell lines and Chinese population with gastric cancer

The prion protein gene PRNP encodes PrPc and PrPsc, causing a number of neurological disorders. Approximately 10-15% of human prion disease is inherited and more than 20 pathogenic mutations have been found. Most of the genetic alterations are point mutations, with the exception of genetic insertions of one to nine extra octapeptide repeats occurring in the important octapeptide-coding region. Our previous work showed that PrPc was overexpressed in gastric cancer. We wondered whether mutations of PrPc existed in human gastric cancer. DNA sequencing and gel electrophoresis were used to determine the possible mutation of PrPc in patients and cell lines of gastric cancer. We found that 1-OPRD (one octapeptide-repeat deletion) homozygosity or heterozygosity exists in several gastric cancer cell lines, e.g. MKN28 and KatoIII are homozygous for 1-OPRD, and SGC7901 and BGC-823 are heterozygous for 1-OPRD. The mutation frequency in tissues of gastric cancer cases is significantly higher than that in the common population (p<0.05). All positive cases in gastric cancer were found to be heterozygous for 1-OPRD. Further study of the variant may be helpful in understanding the mechanisms of occurrence and development of clinical gastric carcinoma as well as the biology of the mysterious gene PRNP.

Enhanced immunogenicity and antitumour effects with heterologous prime-boost regime using vaccines based on MG7-Ag mimotope of gastric cancer

MG7-Ag, gastric cancer-associated antigen, has been shown to be immunogenic and has been used as marker molecule for prognosis. In a previous study, we developed an oral DNA vaccine based on MG7-Ag mimotope. However, we failed to detect cellular immune response using the oral MG7-Ag mimotope DNA vaccine. To induce significant T cell response, we developed a recombinant adenovirus vaccine based on MG7-Ag mimotope and evaluated the efficacy and protective effects of heterologous prime-boost immunization protocol with an oral DNA vaccine previously developed. We found that both vaccines were able to elicit a significant humoral response against MG7-Ag, while the highest serum titre MG7 antibody was detected in mice immunized with the heterologous prime-boost immunization protocol. Enzyme-linked immunospot (ELISPOT) assay demonstrated that the heterologous prime-boost immunization strategy was more efficient in inducing T cell response than the homologous prime-boost strategy. In the tumour challenge assay, 2 of 5 mice immunized with the heterologous prime-boost protocol were tumour free, while none of the mice in homologous prime-boost groups or control groups was tumour free. Those tumour-bearing mice in the heterologous prime-boost regime had smaller tumour masses than their counterparts in the homologous prime-boost groups or control groups. Therefore, our study suggests that vaccines against MG7-Ag induce significant immune response against gastric cancer, and that the heterologous prime-boost protocol using different types of vaccines could achieve better protective effect than the homologous prime-boost protocol.

Downregulation of E-cadherin by hepatitis B virus X antigen in hepatocellullar carcinoma

Hepatitis B virus (HBV)-encoded X antigen (HBxAg) contributes to the development of hepatocellular carcinoma (HCC). A frequent characteristic of HCC is reduced or absent expression of the cell adhesion protein, E-cadherin, although it is not known whether HBxAg plays a role. To address this, the levels of E-cadherin were determined in HBxAg-positive and -negative HepG2 cells in culture, and in tumor and surrounding nontumor liver from a panel of HBV carriers. The results showed an inverse relationship between HBxAg and E-cadherin expression both in tissue culture and in vivo. In HBxAg-positive cells, E-cadherin was suppressed at both the mRNA and protein levels. This was associated with hypermethylation of the E-cadherin promoter. Depressed E-cadherin correlated with HBxAg trans-activation function, as did the migration of HepG2 cells in vitro. Decreased expression of E-cadherin was also associated with the accumulation of beta-catenin in the cytoplasm and/or nuclei in tissues and cell lines, which is characteristic of activated beta-catenin. Additional work showed that HBxAg-activated beta-catenin. Together, these results suggest that the HBxAg is associated with decreased expression of E-cadherin, accumulation of beta-catenin in the cytoplasm and nucleus, and increased cell migration, which may contribute importantly to hepatocarcinogenesis.

Downregulation of E-cadherin by hepatitis B virus X antigen in hepatocellullar carcinoma

Hepatitis B virus (HBV)-encoded X antigen (HBxAg) contributes to the development of hepatocellular carcinoma (HCC). A frequent characteristic of HCC is reduced or absent expression of the cell adhesion protein, E-cadherin, although it is not known whether HBxAg plays a role. To address this, the levels of E-cadherin were determined in HBxAg-positive and -negative HepG2 cells in culture, and in tumor and surrounding nontumor liver from a panel of HBV carriers. The results showed an inverse relationship between HBxAg and E-cadherin expression both in tissue culture and in vivo. In HBxAg-positive cells, E-cadherin was suppressed at both the mRNA and protein levels. This was associated with hypermethylation of the E-cadherin promoter. Depressed E-cadherin correlated with HBxAg trans-activation function, as did the migration of HepG2 cells in vitro. Decreased expression of E-cadherin was also associated with the accumulation of beta-catenin in the cytoplasm and/or nuclei in tissues and cell lines, which is characteristic of activated beta-catenin. Additional work showed that HBxAg-activated beta-catenin. Together, these results suggest that the HBxAg is associated with decreased expression of E-cadherin, accumulation of beta-catenin in the cytoplasm and nucleus, and increased cell migration, which may contribute importantly to hepatocarcinogenesis.

Dual inhibition of the epidermal growth factor and vascular endothelial growth factor phosphorylation for antivascular therapy of human prostate cancer in the prostate of nude mice

BACKGROUND

Androgen-independent prostate cancer (PCa) may be susceptible to modulation of the tumor microenvironment. We determined whether a dual tyrosine kinase inhibitor (AEE788) of the epidermal growth factor receptor (EGF-R) and vascular endothelial growth factor receptor (VEGF-R) combined with chemotherapy can produce therapy of human PCa in nude mice.

METHODS

PC-3MM2 human PCa cells were injected into the prostate of nude mice. Three days later, the mice were randomized into four groups: saline control, paclitaxel, AEE788, and AEE788 and paclitaxel. The mice were treated for 5 weeks and necropsied. Tumor incidence, weight, and incidence of lymph node metastasis were recorded. Tumor tissue was analyzed immunohistochemically.

RESULTS

Treatment of mice with AEE788 or AEE788 plus paclitaxel significantly decreased tumor incidence, total tumor weight, and incidence of lymph node metastasis. AEE788 treatment alone or in combination with paclitaxel inhibited the phosphorylation of EGF-R and VEGF-R on tumor cells and tumor-associated endothelial cells. Therapeutic efficacy correlated with an increase in apoptosis of tumor cells and tumor-associated endothelial cells.

CONCLUSION

Blockade of EGF-R and VEGF-R signaling pathways coupled with chemotherapy suppressed the progressive growth and metastasis of human PCa cells growing orthotopically in nude mice.

Trigemino-cervical response in patients with amyotrophic lateral sclerosis

PURPOSE

The trigemino-cervical response (TCR) was investigated in the patients with amyotrophic lateral sclerosis (ALS) to evaluate its effect for disclosing the bulbar involvement in this disorder.

METHODS

We studied 100 normal subjects and 45 patients with ALS. In all normal subjects, stimulation of the infraorbital nerve on one side produced bilateral short latency waves, which consisted of a positive/negative wave described with the mean peak latency (P20/N30). The mean square root of the ratio between the amplitude of P20/N30 and the mean rectified surface EMG activity preceding the stimulus was described by A value.

RESULTS

The latency of P20 in controls was 18.5 +/- 1.4 ms, N30 was 28.8 +/- 2.8 ms, and the A value was 1.6 +/- 0.5, respectively. In ALS patients, twelve showed absent, seventeen were delayed in the latencies, six were above normal asymmetry on two sides, and ten showed normal. The latency of P20 in ALS patients was 22.9 +/- 9.4 ms, N30 was 33.7 +/- 11.2 ms, and the A value was 1.5 +/- 0.8, respectively. The parameters of the latencies of TCR between ALS patients and the normal controls were statistically different (P < 0.05).

CONCLUSIONS

TCR can be reliably measured in all normal subjects and help in disclosing lower brainstem lesions in ALS patients, even without bulbar symptoms.

Overexpression of DARPP-32 in colorectal adenocarcinoma

Dopamine and cAMP-regulated phosphoprotein (DARPP)-32 is a phosphoprotein that is centrally involved in dopamine signalling pathways. It may play an important role in gastric tumorigenesis. Our aim is to investigate the expression of DARPP-32 protein in colorectal adenocarcinoma. The expression of DARPP-32 was evaluated by immunohistochemical SABC staining and Western blotting. DARPP-32 was specifically localised in colorectal epithelium. The expression of DARPP-32 in colorectal adenocarcinoma tissues 33/42, 78.57% was higher than that in normal colon epithelial tissues (31/60, 51.67%, p <0.05). There was no significant relationship between the expression of DARPP-32 and the differentiation, metastasis and Dukes' stage of colorectal adenocarcinoma (p >0.05). Both DARPP-32 and its truncated isoform t-DARPP were overexpressed in colorectal adenocarcinoma (t=2.306, p=0.028), while t-DARPP was more frequently detected. These results showed that DARPP-32 may play an important role in the regulation of normal colorectal epithelial biology and carcinogenesis.

Conserved glycines in the C terminus of MinC proteins are implicated in their functionality as cell division inhibitors

Alignment of 36 MinC sequences revealed four completely conserved C-terminal glycines. As MinC inhibits cytokinesis in Neisseria gonorrhoeae and Escherichia coli, the functional importance of these glycines in N. gonorrhoeae MinC (MinC(Ng)) and E. coli MinC (MinC(Ec)) was investigated through amino acid substitution by using site-directed mutagenesis. Each mutant was evaluated for its ability to arrest cell division and to interact with itself and MinD. In contrast to overexpression of wild-type MinC, overexpression of mutant proteins in E. coli did not induce filamentation, indicating that they lost functionality. Yeast two-hybrid studies showed that MinC(Ec) interacts with itself and MinD(Ec); however, no interactions involving MinC(Ng) were detected. Therefore, a recombinant MinC protein, with the N terminus of MinC(Ec) and the C terminus of MinC(Ng), was designed to test for a MinC(Ng)-MinD(Ng) interaction. Each MinC mutant interacted with either MinC or MinD but not both, indicating the specificity of glycine residues for particular protein-protein interactions. Each glycine was mapped on the C-terminal surfaces (A, B, and C) of the solved Thermotoga maritima MinC structure. We found that MinC(Ec) G161, residing in close proximity to the A surface, is involved in homodimerization, which is essential for MinC function. Glycines corresponding to MinC(Ec) G135, G154, and G171, located within or adjacent to the B-C surface junction, are critical for MinC-MinD interactions. Circular dichroism revealed no gross structural perturbations of the mutant proteins, although the contribution of glycines to protein flexibility and stability cannot be discounted. Using molecular modeling, we propose that exposed conserved MinC glycines interact with exposed residues of the alpha-7 helix of MinD.

Efficient inhibition of multidrug-resistant human tumors with a recombinant bispecific anti-P-glycoprotein × anti-CD3 diabody

Overexpressing of P-glycoprotein (Pgp) has been shown to be responsible for cancer resistance to multiple chemotherapeutic agents. Immunotherapy with biological agents, such as bispecific antibodies (BsAbs), may represent a promising approach to overcome the emergence of drug resistance. Here we constructed a recombinant BsAb, a diabody, with specificities to both CD3 on human T-lymphocyte and Pgp on cancer cells. The diabody was produced in Escherichia coli in a soluble functional form and purified by an affinity chromatography with a yield of >4 mg/l culture medium in shaker flask. The diabody binds to both CD3 on T-lymphocytes and Pgp on multidrug-resistant (MDR) tumor cells with affinities that are comparable to its respective parental single chain Fv molecules. In the presence of activated human peripheral blood lymphocytes (PBLs), the diabody mediates effectively the lysis of the Pgp-overexpressing human leukemia K562/A02 and epidermoid carcinoma KBv(200) cells, but is much less potent in mediating the lysis of the parent K562 and KB cells. Further, the diabody localized selectively within the K562/A02 xenografts in mice. When combined with activated PBL, the diabody significantly inhibited the growth of K562/A02 and KBv(200), but had no effect on K562 and KB xenografts. In contrast, treatment with doxorubicin, a standard chemotherapeutic agent, only inhibited the growth of K562 and KB, but had no effect on K562/A02 and KBv(200) xenografts. Taken together, our results suggest that the anti-Pgp x anti-CD3 diabody may have a great potential in the treatment of various MDR cancers.

Phrenic and intercostal repetitive nerve stimulation: a useful electroneurophysiological method to detect the respiratory status of myasthenia gravis patients

OBJECTIVE

To get a comprehensive recognition about the profile of phrenic repetitive nerve stimulation (PRNS) and intercostal repetitive nerve stimulation (IRNS) in healthy people, to investigate the electrophysiological features about respiratory function of myasthenia gravis (MG) patients, and to detect the predictive value of IRNS and PRNS on the respiratory deterioration of MG patients during the pulse treatment with large dosage of adrenal corticosteroid.

SUBJECTS AND METHODS

Bilateral PRNS and IRNS with stimulation frequency of 3 and 5 Hz were tested in 28 healthy people and 113 MG patients; limb and cranial repetitive nerve stimulation (RNS), clinical score and forced vital capacity (FVC) were also recorded from those MG patients. Further more, PRNS and IRNS of 36 MG patients were tested 3 days before the beginning of their adrenal corticosteroid pulse treatment, FVC, clinical score and respiratory changes of the MG patients were simultaneously observed.

RESULTS

For healthy people, there were no significant differences in the results of PRNS or IRNS in different age, sex and testing sides. After combining the left result with the right one, the amplitude decrement percentage in PRNS and IRNS was less than 7%. PRNS had more technical difficulty than IRNS. For 113 MG patients, FVC was dependent on the values of PRNS, IRNS and facial RNS. A subclinical respiratory dysfunction was found in patients with type I and II MG. The abnormal rate of PRNS in type IIb MG was similar to that in type III and IV MG, even though a difference in the percentage of amplitude decrement between them was observed. Meanwhile, both the abnormal rate and the percentage of amplitude decrement of IRNS had no difference between type IIb MG and type III and IV MG. The general incidence of abnormal PRNS and abnormal IRNS were higher than those of decreased FVC and clinical dyspnea, and the sensitivity of PRNS in type IIa MG patients was higher than that of IRNS. Among 36 MG patients under the adrenal corticosteroid pulse treatment, 14 showed the newly clinical dyspnea or worsened original one 2 to 13 days after the beginning of the therapy. There were significant difference of the above parameters between the patients with and without respiratory deterioration during the treatment. Logistic regression analysis showed that when the mean value of the bilateral IRNS amplitude decrement was larger than 30%, the odds ratio of the occurrence of the respiratory deterioration was 19.523, for both 3 and 5 Hz stimulation.

CONCLUSIONS

It is recommended that PRNS and IRNS will be defined as abnormal when their amplitude reduces more than 15%. PRNS and IRNS are neurophysiological indices reflecting the damage of respiratory muscles in MG, they are helpful in evaluating the clinical condition correctly and making the classification of MG properly. It is necessary to test the PRNS and IRNS in type II MG patients regularly. Although the respiratory damage during the adrenal corticosteroid treatment was correlated with PRNS, IRNS, FVC, MG clinical score and type, only IRNS had predictive value on the respiratory deterioration during the treatment.

Knowledge about cataract, glaucoma, and age related macular degeneration in the Hong Kong Chinese population

AIMS

Patients' knowledge and participation in their care are important in prevention of blindness from common eye diseases such as cataract, glaucoma, and age related macular degeneration (AMD). The aim of this study was to measure knowledge of these conditions in the Hong Kong Chinese population.

METHODS

Subjects aged 40 and above in the Shatin district of Hong Kong were randomly selected as part of a larger study of causes of adult visual loss. The subjects received eye examinations in which the primary cause of visual disability was recorded. The respondents were asked by trained interviewers in a standardised fashion about their knowledge of cataract, glaucoma, and AMD. Their answers were rated for accuracy by a senior ophthalmologist.

RESULTS

Out of the 2538 eyes examined, 7.0% had visual acuity less than 6/18. Fully 69.6% of the visual disability for those aged 60 or above was caused by cataract, AMD, or glaucoma. Awareness of cataract in particular was high, in that over 90% of respondents had heard of it. However, only 22.9% of them could describe cataract symptoms correctly, and these percentages were even lower in glaucoma (10.2%) and AMD (<1%). Over 40% of subjects did not know that surgery was an appropriate treatment for cataract.

CONCLUSION

This sample of the Hong Kong Chinese population had limited knowledge of common eye diseases. Educational programmes to enhance public awareness may be needed to improve the effectiveness of health promotion and thus prevent unnecessary blindness.

Multidrug-resistance-associated protein MGr1-Ag is identical to the human 37-kDa laminin receptor precursor

We report the isolation and functional characterization of the gene encoding MGr1-Ag, a multidrug-resistance-associated protein. A lambdagt11 cDNA library derived from colorectal carcinoma SW480 cells was screened with monoclonal antibody MGr1. DNA homology analysis of 22 positive clones (designated R1-R22) suggested human 37-kDa laminin receptor precursor (37LRP, R7/R9/R15/R16/R19/R20) and a novel gene (R22) as candidate genes encoding MGr1-Ag. Western blot analysis showed that anti-R20 serum reacted with a unique protein band that was consistent with MGr1-Ag, while anti-R22 serum could not react with MGr1-Ag. The coding gene for MGr1-Ag was amplified using reverse transcription-PCR. Sequence analysis revealed that the MGr1-Ag and 37LRP genes shared the same coding sequence. An in vitro drug sensitivity assay indicated that down-regulation of 37LRP by an antisense technique could significantly enhance the cytotoxicity of anticancer drugs to gastric cancer cells. Thus we draw the conclusion that MGr1-Ag is identical to 37LRP.