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Biomedical subjects

Y X Hu

Publications and source records attributed to Y X Hu.

At least 19 recordsLinked to original sources
PubMed2003

Patterning hydroxyapatite biocoating by electrophoretic deposition.

Patterned bioceramic coatings may find potential applications in orthopedic implants and biosensors. In this study, various hydroxyapatite (HA) patterns were created on silicon and titanium substrates. Electrophoretic deposition technique was used together with surface patterning of the cathode specimen. When gold/palladium patterns (hexagons, spherical dots, etc.) were created on the cathode surface, HA colloidal particles in ethanol would preferentially deposit on the gold-coated area and form patterns. When silicon, instead of gold, was evaporated onto a conducting cathode surface, HA mainly deposited on the exposed area of the substrate. Detailed mechanisms for forming HA patterns may involve local concentration of the electric field when a second metal is patterned on the cathode. The difference in electric field across the two metals on the cathode also enhances HA patterning through an electrohydrodynamic process. This study demonstrated the possibility and flexibility of electrophoretic deposition in patterning charged particles onto a substrate.

Chemistry, Physical↗
PubMed2001

Recombinant HIV-1 glycoprotein 120 induces distinct types of delayed hypersensitivity in persons with or without pre-existing immunologic memory.

Induction of T cell help is critical in HIV-1 control and potentially in prevention by immunization. A practical approach is needed to identify HIV-1-specific helper activities in vivo. We explored the feasibility of measuring delayed-type hypersensitivity (DTH) following intradermal injection of recombinant soluble HIV-1(MN) glycoprotein 120 in HIV-1-infected, vaccinated, and exposed individuals. DTH reactions were elicited within 48 h in 16 of 29 untreated, infected patients and in 24 of 30 uninfected vaccinees. Concomitant envelope-specific lymphoproliferation in vitro was undetectable among 9 infected patients tested with positive envelope-specific DTH. By contrast, no 48-h DTH reactions occurred among 25 high risk and 32 low risk, uninfected volunteers. However, 7--12 days after injection, 10 (40%) high risk and 11 (34%) low risk individuals developed induration resembling DTH, and the cellular infiltrates contained monocytes and T cells. Five of 18 examined also developed anti-gp120 Abs. The very delayed time course and lack of correlation with previous Ag exposure clearly distinguish this reaction from DTH. Thus, HIV-1 skin testing can identify persons with HIV-specific recall responses resulting from infection, in the absence of in vitro lymphoproliferation, and from vaccination. In contrast, very late reactivities may signify chemotactic properties of the envelope protein and/or herald the induction of primary HIV-specific Th1-type immunity.

AIDS Vaccines↗
PubMed2000

An immunohistochemical analysis of p27 expression in human pancreatic carcinomas.

p27 is known as one of the candidate tumor suppressor genes. Although abnormalities including deletion and mutation in this gene are rarely detected, loss of p27 expression has been reported to be correlated with the high degree of malignancy in many human cancers. In the present study, we investigated the status of p27 expression in human pancreatic carcinoma (PC) and assessed the clinicopathologic significance of loss of p27 expression in the development and progression of this malignancy using immunohistochemistry. No nuclear staining for p27 protein existed in 65 (65.7%) of the 99 PC tumors examined. Furthermore, loss of p27 expression was correlated with tumor grade (G1 versus G2 or G3, p < 0.05) or clinical stage (I and II versus III and IV, p < 0.01). The above data suggest that loss of p27 expression is a very common event in PC, and moreover, this alteration might contribute to the progression of this malignant disease. Key Words: Pancreatic carcinoma-p27 protein expression-Immunohistochemistry.

Cell Cycle Proteins↗
PubMed1999

K-ras mutations in duodenal aspirate without secretin stimulation for screening of pancreatic and biliary tract carcinoma.

BACKGROUND: K-ras mutations at codon 12 (KRM) have been detected in over 80% of tissues and pure pancreatic juice (PPJ) samples from patients with pancreatic carcinoma (PCa) and are promising genetic tumor markers. Aspirating PPJ not only requires technical skill, but is also exhausting for patients. The authors attempted to evaluate whether the detection of KRM in the duodenal aspirate (DA) obtained immediately after endoscopic retrograde cholangiopancreatography (ERCP), an easier sample-collecting method than collecting PPJ, could be useful for the diagnosis of PCa and biliary tract carcinoma (BTCa). METHODS: DA was collected endoscopically without secretin stimulation immediately after the ERCP procedure from 160 patients: 38 patients with PCa, 38 with chronic pancreatitis (CP), 22 with BTCa, 20 with adenomyomatosis of the gallbladder (AGB), 22 with cholecystolithiasis (CCL), and 20 control subjects. Mutant allele specific amplification (MASA), which is a highly sensitive method for detecting KRM, was performed, with the DNAs extracted from these samples by phenol-chloroform. RESULTS: The incidence of KRM in DA by MASA was 25 (66%) of the 38 PCa cases, 12 (32%) of the 38 CP cases, and 12 (55%) of the 22 BTCa cases. There was no patient with positive KRM in DA among the 20 cases of AGB, 22 of CCL, and 20 control subjects. The sensitivity was 62% and the specificity 88% in this study design. The KRM incidence was found to be relatively high for the patients with PCa and BTCa by MASA, which is a highly sensitive method, although the incidence of KRM in DA from the patients with PCa was not as high as the incidence in their PPJ with secretin stimulation. CONCLUSIONS: MASA showed a relatively high incidence of KRM even in the DA, which was easily obtained from the patients with PCa and BTCa without secretin stimulation immediately after ERCP. These results suggest that the detection of KRM in the DA by MASA is useful for the screening of both PCa and BTCa.

Adult↗
PubMed1999

Bcl-2 expression related to altered p53 protein and its impact on the progression of human pancreatic carcinoma.

p53 and Bcl-2 are two important factors related to apoptosis and tumorigenesis. In this study, a series of 52 cases of pancreatic carcinoma (PC) were investigated using an immunohistochemical assay to determine whether altered expression of Bcl-2 and p53 has an impact on the progression of this malignancy. Cytoplasmic immunoreactivity for Bcl-2 and nuclear staining of p53 was found in 12 (23.1%) and 32 (63.5%) cases of PC respectively. Furthermore, an inverse correlation between the expression of p53 and Bcl-2 existed in this series (P < 0.01). In a subgroup, the proportion of tumours showing that p53-positive and Bcl-2-negative staining was increased with increasing histological grade and clinical stage (P < 0.05), and moreover, the survival period of those patients whose tumour had this staining was shorter than those with other staining patterns of combined p53 and Bcl-2 (P < 0.05). Therefore, it is concluded that simultaneously aberrant expression of Bcl-2 and p53 may confer PC with more malignant clinicopathological characteristics.

Adenocarcinoma↗
PubMed1998

Quantitative determination of K-ras mutations in pancreatic juice for diagnosis of pancreatic cancer using hybridization protection assay.

K-ras mutations at codon 12 (KRM) have been detected in approximately 80% of samples of pure pancreatic juice (PPJ) from patients with pancreatic cancer (PCa) and are a promising potential tumor marker. However, the frequent presence of KRM was reported in PPJ from noncancerous patients as determined by a highly sensitive method, raising questions as to the cancer specificity of this marker. Therefore we evaluated whether the hybridization protection assay (HPA), which can quantitatively determine KRM in PPJ, is useful for the diagnosis of PCa, differentiating from chronic pancreatitis (CP). PPJ was collected endoscopically from 29 patients with PCa, 26 patients with CP, and the 11 cases as the control group. Polymerase chain reaction (PCR) and HPA using an acridinium ester-labeled DNA probe for KRM were performed with DNA extracted from these samples. The results were compared with those obtained by PCR-restriction fragment length polymorphism (RFLP). The mean + 2 SD of chemiluminescence in the control group was 11,020 RLUs. When 11,020 RLUs was taken as the cut-off value, KRM was detected by PCR-HPA in 19 (66%) of 29 of PCa and one (4%) of 26 of CP cases. Analysis of PPJ by PCR-RFLP demonstrated KRM in 22 (79%) of 28 of PCa and five (19%) of 26 of CP cases. However, four of five patients with CP who were KRM-positive by PCR-RFLP were defined as negative by PCR-HPA, suggesting that PCR-HPA is superior to PCR-RFLP for the discrimination between PCa and CP. These findings indicate that quantitative analysis of KRM in PPJ using the PCR-HPA method is a promising approach for the diagnosis of PCa, differentiating from CP with a suitable cut-off value, as in the case with the use of conventional serum tumor marker.

Aged↗
PubMed1998

Infrequent expression of p21 is related to altered p53 protein in pancreatic carcinoma.

This study is designed to investigate the expression of p21 and its relation to altered p53 protein in pancreatic carcinoma (PC). Immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections of PC was performed using a monoclonal antibody against p21 (187), with a parallel examination of altered p53 protein. The expression of p21 was only found in 12 of 58 (20.7%) PCs and, moreover, was mainly restricted to the well-differentiated ductal epithelium. Sixty-four % (37 of 58) of PCs showed positive p53 staining, and this change was significantly related to the absence of p21 expression (P < 0.01). In a subgroup, the proportion of the undetectable p21 expression and the expression of p53 were increased with increasing tumor grade but decreased with advancing clinical stage. The results of the present study suggest that the absence of p21 expression is very common in PCs and appears to relate to altered p53 protein. Moreover, the abnormalities involving the expression of p21 and p53 may play a more important role in the development than in the progression of this malignancy.

Adult↗
PubMed1997

[The development of x-ray machine mAs tester].

The numeric readout mAs tester described in this paper has the advantage of simple and practical structure. It is suitable for regulations and repairs of x-ray machine for clinical units.

Equipment Design↗
PubMed1997

Frequent loss of p16 expression and its correlation with clinicopathological parameters in pancreatic carcinoma.

Expression of the p16 gene product in human primary pancreatic carcinoma (PC) was investigated in paraffin-embedded tissue using a monoclonal antibody against p16 protein, clone G175-405, by means of immunohistochemistry, and the correlation of results with various clinicopathological parameters was evaluated. All six cases of normal pancreas and all but 1 of 20 cases of chronic pancreatitis expressed p16 protein, whereas 37.5% (3 of 8) of cystadenomas and 41. 9% (26 of 62) of PCs lost p16 expression. There was a significant difference between chronic pancreatitis and PC for frequency of the loss of p16 expression (P < 0.01). Moreover, loss of p16 expression in pancreatic malignancy was significantly associated with histological grade (G1 versus G2 and G3, P < 0.01) but not with sex, age, clinical stage, tumor location, or resectability. The survival period was shorter and metastasis is more likely in those cases that did not show p16 expression than those that did.

Adenocarcinoma↗
PubMed1995

Immortalization of human cells by mutant and chimeric primate polyomavirus T-antigen genes.

Human fibroblasts were morphologically transformed with wild type and mutant SV40 T-antigens (T-Ags) and with SV40/JCV and SV40/BKV chimeric T-Ags. The transformants were then assayed for the attainment of immortal cell growth. Several observations relating T-Ag and T-Ag domains to immortalization were made. Approximately 10% of SV40-transformants became immortal. Transformants generated by transfection or infection of cells with C-terminal T-Ag deletion mutants of SV40 did not immortalize. SV40/JCV and SV40/BKV chimeric T-Ags, containing C-terminal sequences from JCV or BKV, immortalized cells more efficiently than did the intact SV40 T-Ag, suggesting that the C-termini of the JCV and BKV T-Ags contain an enhanced immortalization function. However, chimeras in which the N-terminal or proximal-central portions of T-Ag were composed of JCV sequences failed to immortalize but did induce transformation. Constructs in which the JCV T-Ag Rb binding domain was replaced with SV40 sequences transformed human cells, but again the cells failed to immortalize. Transformants and immortalized cell lines produced by some SV40/JCV chimeras, contained p53 which was unbound by T-Ag. This occurred under conditions where p53 from SV40 and SV40/BKV transformants was bound to T-Ag. This may reflect the reduced stability of the SV40/JCV T-Ags.

Antigens, Polyomavirus Transforming↗
PubMed1994

[Diagnosis between condyloma acuminatum and pseudocondyloma in lower female genital tract as determined by a PCR-based method].

From Jan. 1990-Aug. 1992, 616 patients with papillomatous growth of the lower female genital tract (the nodular type 307 cases, the papular type 309 cases) were investigated as determined by a PCR (polymerase chain reaction)-based method, associated with immunohistochemistry avidin biotin complex (ABC), electron microscopy, histopathology, colposcopy and clinical follow-up. The PCR is the most sensitive and specific method. Using PCR the HPV DNA 6.11.16.18.33 were positive in 97.90% of the nodular type. However HPV DNA were positive in 1.10% of the papular type. In the patients with both type, HPV DNA were also positive in nodular, but negative in papular. In the nodular type the HPV-Ag present in 53.55% by ABC method, the koilocytes were 70.49% by microscopy, HPV particles were seen in 5 out of 85 samples by electron microscopy. So that the nodular type (typical cauliflower like) is genital warts (condyloma acuminatum) by HPV infection. The papular type (typical papular or finger like) growth on the mucosal surface of the labia minora of lower vagina. They were negative for HPV DNA, HPV-Ag, HPV particles and koilocytes. On follow-up observation for 3 months to 2 years they had not developed to nodular type and no sexually transmitted feature was observed. The papular type is pseudocondyloma.

Adolescent↗
PubMed1993

[A pathological analysis of 51 cases of renal osteodystrophy].

Renal osteodystrophy is a metabolic bone disease of chronic renal failure. The long-standing alterations in mineral metabolism generated by renal failure have a profound effect on the skeleton and induce severe systemic metabolic bone disease. Iliac crest biopsy was performed in 51 patients of chronic renal failure and examined with microscopy. The histological bone changes are characterized by ostitis fibrosa, increased resorption of bone and number of osteoclasts, increased osteoid volume (osteoblastic osteoid and acellular osteoid), active remodelling of bone and aluminum deposition in bone. According to the histological appearance, advanced renal bone disease can be subdivided into three major histological groups: secondly hyperparathyroid bone disease (high turnover uremic osteodystrophy), osteomalacia (low turnover uremic osteodystrophy) and mixed uremic osteodystrophy consisting of mild to moderate hyperparathyroid bone disease and defective mineralization. Aluminum-related bone changes can be seen in varying degrees in all these groups. Even though these groups do not fully represent separate entities and transformation from one form to another can occur, it is essential to distinguish them since therapy can be tailored according to the predominant histologic findings.

Aluminum↗
PubMed1992

Effect of gas atmosphere on the development of one-cell bovine embryos in two culture systems.

The effect of two concentrations of oxygen on the development of bovine embryos was compared using two separate co-culture systems. In Experiment I, bovine oocytes were matured and fertilized in vitro and were then co-cultured for 7 days in 20 mul drops of M199 with 10% fetal calf serum containing oviduct cells. When cultures were performed in an atmosphere of 5% CO(2) in air (20% O(2)) or in a mixture of 5% CO(2), 5% O(2) and 90% N(2) (5% O(2)), 22 of 179 (12%) and 56 of 179 (31%) zygotes developed to or beyond the late morula stage (P<0.0001), respectively. After freezing, thawing and 48 hours of additional culture, 2 of 21 (10%) and 18 of 53 (34%) embryos were judged viable (P<0.001) within the respective treatment groups. In Experiment II, zygotes produced by the same means were co-cultured in 0.5 ml of M199 containing 10% fetal calf serum with monolayers of buffalo rat liver (BRL) cells. In 20% O(2), 51 of 177 (29%) zygotes developed into viable embryos, while in 5% O(2) only 9 of 177 (5%) were judged viable after 7 days of culture (P<0.0001). Post-freezing survival rates were 53% and 67% for embryos from the two respective oxygen concentration treatment groups. The transfer of 20 Grade 1 frozen/thawed embryos produced by co-culture with BRL cells produced six pregnancies (30%). These experiments show that the critical effect of oxygen concentration on embryo development in vitro and the ability of embryos produced by in vitro procedures to survive freezing can be influenced by the type of culture system employed.

Journal Article↗
PubMed1992

Use of ethylene glycol as a cryoprotectant for bovine embryos allowing direct transfer of frozen-thawed embryos to recipient females.

Four experiments were conducted to define a system for the direct transfer of frozen-thawed bovine embryos to recipient females. In Experiment I, nonsurgically recovered embryos were frozen in 1.5 M ethylene glycol (EG), 1.5 M propylene glycol (PG), 1.5 M DMSO or 1.4 M glycerol (GLY), and then thawed and placed directly into holding medium. Viability at 72 hours of post-thaw culture was 70, 11, 25 and 30% for the four groups, respectively. In Experiments II and III, 1.0, 1.5 and 2.0 M concentrations of EG were compared; a concentration of 1.5 M appeared to provide optimal cryopreservation and survival after direct rehydration. In Experiment IV, embryos were packaged in straws containing only 1.5 M EG, in straws containing a column of 1.5 M EG and the embryo and two columns of PB1 in a 1:3 ratio of volumes (EG PB1 ), or were frozen in 1.4 M glycerol. After thawing, embryos in EG and EG PB1 treatments were transferred directly to recipient females, while embryos frozen in GLY were rehydrated using a three-step procedure. In the first trial, pregnancy rates at approximately 60 days of gestation for embryos frozen in EG and GLY groups were 39 and 62%, respectively (P<0.10). In the second trial, the pregnancy rate for embryos frozen in EG PB1 was equal to that of embryos frozen in GLY (50% in both groups). These experiments demonstrate the potential for using ethylene glycol as a cryoprotectant for bovine embryos, thus permitting direct transfer of frozen-thawed embryos to recipient females.

Journal Article↗
PubMed1992

[Analysis of the therapeutic effect of radial keratotomy].

666 cases (1,302 eyes) of myopia were performed radial keratotomy and 738 eyes were followed up for 6-9 months. Before surgery, the mean spherical refraction was -6.65D and the mean keratometry was 44.17D with uncorrected visual acuity of 0.03-0.4. 6-9 months after operation, the mean spherical refraction decreased by 4.76D, or an average decrement of 2.69D for mild myopia, 4.07D for moderate myopia, 5.28D for high myopia, and 6.00D for very high myopia. The percentages of eyes with postoperative uncorrected visual acuity > or = 0.5 were 100%, 84.86%, 58.01% and 20.59% for mild, moderate, high and very high myopia respectively, and the corresponding figures for postoperative uncorrected visual acuity > or = 1.0 were 89.29%, 55.71%, 17.79% and 3.92% respectively. Complications were few.

Adolescent↗
PubMed1991

[Determination of circulating antigen in cysticercosis patients using McAb-based ELISA].

For the first time, the determination of circulating antigen in patients with cysticercosis using specific monoclonal antibody against cysticercus antigen (CCyl) based on inhibitive ELISA was reported. The circulating antigens were detected in the sera from 83 patients with cysticercosis, the positive rate being 71.1%. The range of the detectable serum antigen concentrations was 0.16-128 micrograms/ml. In 41 cases of cysticercosis patients, circulating antigens were determined in both sera and cerebrospinal fluids, the positive rates being 68.3% and 78% respectively, the total positive rate being 90.2%. In 114 sera from normal persons, circulating antigen was absent. In 30 sera from patients with hydatidosis, 30 with clonorchiasis, 20 with schistosomiasis japonica, 24 with paragonimiasis, and 5 sera collected from non-parasitosis patients, serum circulating antigen was not detectable. In another 10 non-parasitosis patients, circulating antigen was not found in cerebrospinal fluid. After chemotherapy for one half to one year, in 21 out of 23 cases of cysticercosis patients, the circulating antigen levels in sera dropped to zero, except for two cases having an antigen level of 0.64 micrograms/ml and 1.6 micrograms/ml, respectively. Our results showed that the determination of the circulating cysticercus antigen was very specific for the diagnosis of active infection of cysticercosis and could be used as a rational tool in monitoring the effectiveness of chemotherapy.

Animals↗
PubMed1991

[The significance of immunoblot in serodiagnosis of cysticercosis cellulosae].

50, 92 and 30 samples collected respectively from cases with cysticercosis cellulosae, other parasitic diseases and normal controls were examined with SDS-gradient (5-20%) polyacrylamide-gel electrophoresis and immunoblot. The results showed that 26 KD protein band of the cysticercus antigen is highly specific for cysticercosis and no cross reaction could be seen in patients with other parasitic diseases, especially hydatid disease, and healthy controls. As we know that the cysticercus antigen usually has a high cross-reaction rate with hydatidosis by ELISA method, the positive rate of this test for cysticercosis is 70% in comparison with 80% and 76% of ELISA and CFT respectively and the difference in the figures of these three tests has no statistical significance. Our study suggested that this method is valuable in clinical diagnosis and epidemiological surveys for research work on cysticercosis cellulosae.

Animals↗