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Biomedical subjects

K Zhu

Publications and source records attributed to K Zhu.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Percutaneous transfemoral arterial implantation of drug delivery system for arterial infusion therapy of advanced primary hepatic carcinoma].

OBJECTIVE: To study the efficiency of arterial infusion chemotherapy via drug delivery system (DDS) for advanced primary hepatic carcinoma. METHODS: Hepatic arterial infusion chemotherapy was performed in 82 cases of primary hepatic carcinoma with no indication for operation or transarterial embolism treatment. The patients were divided into 2 group as follows: (1) Group A: 42 patients were treated intra-arterially once every 1 or 2 weeks via implanted DDS. (2) Group B: 40 patients were treated through one bolus arterial infusion chemotherapy, once every month. RESULTS: The response rate (CR + PR) was 38.1% and 15.0% respectively in group A and B (P < 0.05); the 0.5-, 1- and 2- year survival rate was 61.9%, 28.6% and 9.5% respectively in group A, but 20%, 5%, 0% respectively in group B (P < 0.01); Liver, biliary, gastrointestinal and bone marrow toxicity in group A patients was greatly lower than those in group B patients. CONCLUSION: Intermittent arterial infusion chemotherapy via DDS significantly improves survival and quality of life in patients with advanced primary hepatic carcinoma.

Adult↗
PubMed1998

[Determination of serotonin in rat brain by gas chromatography/mass spectrometry].

A GC/MS method for the determination of serotonin (5-hydroxytryptamine, 5-HT) has been developed. 5-HT in homogenized rat brain was acylated and extracted into EtOAc. The acylate was further derivatized with heptafluorbutyl anhydride and formed a spirocyclic pentafluoropropionyl derivative. Subsequent analysis of 5-HT derivative by gas chromatography-electron capture negative ion chemical ionization mass spectrometry was highly specific and sensitive. The assay is linear from 0.5 to 50 micrograms/L with a linear equation of Y = 0.134 8X - 0.07995, r = 0.999. The recovery was 98.2% +/- 3.8% (n = 10) and the limit of detection was 0.5 microgram/L. The reproducibility of 5-HT determination in rat brain was less than 10% (RSD) at both levels of 1.0 microgram/L and 50.0 micrograms/L. The method has been applied to analysis of 5-HT in the dose rat brain successfully.

Animals↗
PubMed1998

[Preparation of 5-fluoruracil-poly-alpha, beta(2-hydroxyethy1)-DL-asparamide and in-vivo release in rabbit].

A polymer release drug was prepared by poly-alpha, beta-(2-hydroxyethyl)-DL-asparamide(PHEA) and 5-fluorouracil. As a model drug 5-fluorouracil was conjugated into the biodegradable polymer by chemical bond. The released drug was determined to be about 37.1% (w/w) and it was characterized by IR spectrum and differential scanning calorimetry (DSC). Two forms of drugs, rod and suspension were prepared and in vivo release experiment were carried out in rabbits. The experimental result showed that the rod form of drug can in some degree reduce initial burst.

Animals↗
PubMed1997

Isolation and characterization of americanin, a specific inhibitor of thrombin, from the salivary glands of the lone star tick Amblyomma americanum (L.).

A thrombin (EC 3.4.21.5) inhibitor (americanin) was isolated from the salivary glands of the lone star tick Amblyomma americanum (L.) using reversed-phase chromatography and anion-exchange chromatography. Americanin did not inhibit any other protease tested, including factor Xa, plasmin, trypsin, chymotrypsin, elastase, papain, pepsin, and carboxypeptidase. The inhibition of thrombin by americanin decreased dramatically with dilution of the reaction mixture including thrombin, its substrate, and americanin. When thrombin assays were performed in the presence of americanin, the reaction curve showed a time-dependent inhibition. Significant inhibition was observed when americanin concentration was approximately equal to that of thrombin, with a Ki of 0.073 nM. The results suggest that americanin is a specific, reversible, competitive, slow, tight-binding inhibitor of thrombin.

Animals↗
PubMed1997

A novel phospholipase A2 activity in saliva of the lone star tick, Amblyomma americanum (L.).

Saliva from female lone star ticks, Amblyomma americanum, contained a novel phospholipase A2 (PLA2) activity that hydrolyzed 14C-arachidonate from 14C-arachidonyl phosphatidylcholine. The tick saliva PLA2 (ts-PLA2) was active over a broad pH range (4.5-11.5) with two distinct pH optima of pH 5.5 and 9.5. Though extracellular PLA2s are reported to be activated by millimolar Ca2+, ts-PLA2 was sensitive to submicromolar Ca2+ and was half-maximally activated by 3.5 microM Ca2+. Tick saliva contains > 500 microM Ca2+ and the feeding lesion in the host is expected to contain millimolar Ca2+. Saliva exhibited a single peak of PLA2 activity corresponding to a molecular weight of 55.7 +/- 1.3 kDa by size exclusion chromatography. The ts-PLA2 was unaffected by a variety of compounds known to inhibit either secreted or cytosolic PLA2s from other sources. However, ts-PLA2 was inhibited by the substrate analog, oleyloxyethyl phosphorylcholine (IC50 = 1.4 microM), and the end product, arachidonic acid (IC50 = 38 microM). Low concentrations of dithiothreitol did not greatly affect ts-PLA2, but activity was reduced at higher concentrations. The PLA2 activity found in A. americanum salivary glands showed many similarities to ts-PLA2, but also some distinct differences. Secreted at the tick-host interface, ts-PLA2 is thought to play an important, but unknown, role during the prolonged tick feeding.

Animals↗
PubMed1997

Estrogen receptor status of breast cancer: a marker of different stages of tumor or different entities of the disease?

Breast cancer can be divided into two types according to the estrogen receptor (ER) level of the tumor: ER-positive and ER-negative. Two hypotheses have been raised about the relationship between ER-positive and ER-negative breast tumors. One hypothesis considers ER status as an indicator of a different stage of the disease. The other regards ER-positive and ER-negative tumors as different entities. For both etiological and biological studies of breast cancer it is important to know which hypothesis is correct. In this paper, we review evidence for and against each hypothesis and suggest issues to be addressed in future studies.

Biomarkers, Tumor↗
PubMed1997

The relationship of hepatitis history and pathological diagnosis of primary liver cancer.

During the analysis of risk factors in relation to primary liver cancer, we noticed an association between the confirmed (as opposed to probable) pathologic diagnosis of liver cancer and a positive history of hepatitis. This report pursues the observation using data from the Selected Cancers Study. Study subjects included 168 men who lived in areas covered by eight cancer registries in the U.S., and were pathologically diagnosed with confirmed or probable primary liver cancer during 1984-1988. The results showed that men with confirmed primary liver cancer were six times more likely to have a hepatitis diagnosed within 3 years before liver cancer detection, compared with those with probable primary liver cancer. Further analyses showed that men with a confirmed primary liver cancer or with a recent hepatitis more likely had a tissue specimen obtained from a surgery, and less likely had one from an aspiration. Upon adjustment for type of specimen, the association between pathological confirmation of primary liver cancer and recent hepatitis persisted. The results raised questions whether recent hepatitis and its pathologic changes influence choice of tissue-collecting procedure and ultimate pathological diagnosis of primary liver cancer. Other factors that might be related to the findings also need to be examined in future studies.

Adolescent↗
PubMed1997

Identification of hemolytic activity in saliva of the lone star tick (Acari:Ixodidae).

Hemolytic activity was identified in the saliva of Amblyomma americanum (L.) when red blood cells from sheep were incubated with tick saliva in the presence of phosphatidylcholine and sodium deoxycholate. The hemolytic activity was destroyed by boiling or treating with trypsin. The hemolytic activity in tick saliva was calcium-dependent, and inhibited by a phospholipase A2 inhibitor oleyloxyethyl phosphorylcholine. Phosphatidylserine could replace phosphatidylcholine in the hemolytic assays but phosphatidylethanolamine and phosphatidylinositol were ineffective. Size exclusion chromatography of tick saliva revealed one peak of hemolytic activity, which correlated with the activity of tick salivary phospholipase A2, both having a molecular weight approximately 55,000 daltons. These results suggest that the hemolytic activity in tick saliva results from salivary phospholipase A2. The hemolytic activity in tick saliva may play a role in lysing host red blood cells, thus facilitating the tick digestive process.

Animals↗
PubMed1997

Cigarette smoking and nasopharyngeal cancer: an analysis of the relationship according to age at starting smoking and age at diagnosis.

To examine whether the association between smoking and nasopharyngeal cancer varies according to age at starting smoking and age at diagnosis of the disease, we compared 113 men with nasopharyngeal cancer diagnosed between 31 and 59 years old who lived within eight cancer registry areas to 1,910 controls selected by random-digit telephone dialing. Compared to smoking which began at the age of 22 years or older, the risk estimates were 0.4 (95% confidence interval (CI) 0.2-0.9) and 0.8 (95%CI 0.4-1.5) for smoking begun at the ages of 18-21 and 17 years or younger, when adjusted for pack-years smoked and other potential confounders (p for trend > 0.8). In contrast, the risk estimates adjusted for age at starting smoking and other variables were 1.3 (95%CI 0.7-2.6), 1.9(95%CI 0.9-4.0) and 3.0(95%CI 1.4-6.2) for 15-29.9, 30-44.9 and 45 or over, relative to 15 or less pack-years smoked (p for trend < 0.005). The analyses were repeated for subgroups in terms of age at diagnosis. The relative risks of ever-smoking and the dose-effect relation between pack-years and the risk of the disease were not significantly different between men whose cancer was diagnosed at the age 49 or younger and those whose tumor was diagnosed between the ages 50 and 59. This study suggests that the magnitude of the risk for nasopharyngeal cancer may not vary significantly with the age at which smoking begins, and age at which the disease is diagnosed.

Adult↗
PubMed1997

[Primary study on Fas-mediated apoptosis in the liver tissue of patients with chronic hepatitis B].

Apoptosis may be the cause of cell death that activate gene due to certain factors. It has been suggested that apoptosis is mediated through Fas antigen. To evaluate the role of the Fas antigen and apoptosis in chronic hepatitis B (CHB), we observed the Fas expression and nuclear DNA fragement in CHB hepatic tissue using immunohistochemistry and TUNEL method respectively. The results showed that the Fas antigen expressing cells located mainly in inflammation infiltrating area but less in non-inflammation infiltrating area; the positive cells were found particularly among infiltrating lymphocytes at the advancing edges of "piecemeal necrosis" near the portal regions. The expression of Fas was detected mainly in the cytoplasm of hepatocytes. 46 samples from 56 CHB patients were Fas positive, the posive rate reached 82%. The Linear Correlation and Regression analysis suggested that there was a direct correlation between nuclear DNA fragement and Fas expression. These findings suggest that the apoptosis mediated through Fas antigen may play an important role in pathogenesis of CHB.

Adolescent↗
PubMed1997

Identification and characterization of anticoagulant activities in the saliva of the lone star tick, Amblyomma americanum (L.).

Anticoagulant activities against both the extrinsic and intrinsic coagulation pathways were identified in the saliva of partially fed female lone star ticks, Amblyomma americanum (L.). The activities of factor Xa and thrombin in the common pathway of the coagulation cascade were inhibited by tick saliva. The greatest anticoagulant activities were found in the saliva of ticks weighing more than 200 mg. The anticoagulant activities in tick saliva could be detected without preincubation of tick saliva with sheep plasma, but preincubation significantly increased the activities. Tick saliva anticoagulant activities were abolished by boiling for 15 min or being treated with trypsin for 1 hr. Phosphatidylcholine (3 mM) and phospholipase A2 inhibitor oleyloxyethyl phosphorylcholine (0.2 mM) did not affect the anticoagulant activities significantly, suggesting that the phospholipase A2 activity found in tick saliva does not contribute to the anticoagulant activities. Size exclusion high performance liquid chromatography revealed that the molecular weights of the anticoagulant activities were approximately 16,000 D. The anticoagulant activities in tick saliva are believed to play an important role in facilitating tick feeding by helping overcome the host hemostatic system.

Animals↗
PubMed1997

[The therapeutic effect of purified human leucocytic interferon-alpha on hemorrhagic fever with renal syndrome].

In order to know the therapeutic effect of purified human leucocytic interferon-alpha on hemorrhagic fever with renal syndrome diagnosed early (< or = 5 days). We treated 23 cases with clinical prognosis and antiviral effect significantly better than those of 21 cases in a random control group. The membrane protein (MP), nucleo protein (NP) in peripheral blood mononuclear cells (PBMC) and urine, the serum antibodies to MP and NP were determined before treatment and 2, 4, 6, 8, 10 days after the beginning of the treatment. The results showed that in the treatment group, the expressin of MP and NP in PBMC were significantly depressed. The rate of negative turning of MP and NP in PBMC was 65.22% (15/23) and 69.57% (16/23) in 10 days, while in the control group, it was 19.05% (4/21) and 14.29% (3/21). The rate of negative turning of MP and NP in urine were 78.57% (11/14) and 90.91% (10/11) and that in the control group was 30.00% (3/10) and 16.66% (1/6). There was a significant difference between the two groups (P < 0.01). The results indicated that IFN-alpha could attenuate the lesions caused directly by virus, improve patients condition and raise the cure rate through depressing the expression of the virus.

Adult↗
PubMed1996

Vasectomy and prostate cancer: a case-control study in a health maintenance organization.

A case-control study was conducted within Group Health Cooperative of Puget Sound to evaluate the relation between prior vasectomy and the risk of prostate cancer. Cases consisted of 175 men newly diagnosed with histologically confirmed prostate cancer during 1989-1991. A total of 258 controls, matched to cases on birth year and membership status, were randomly selected from the general membership of the plan. Information was collected from mailed questionnaires and medical records on medical history, including prior vasectomy, anthropometric measures, family history of prostate cancer, personal habits, and medical care utilization, and demographic factors. Conditional logistic regression analyses showed that the odds ratio for prostate cancer associated with vasectomy was 0.86 (95% confidence interval 0.57-1.32) after adjustment for confounders. The odds ratio estimate did not differ substantially by age at vasectomy or time since vasectomy. However, the odds ratio estimate for prostate cancer associated with vasectomy tended to be increased among men who had a father or brother with prostate cancer. Nevertheless, the increased risk may be related to detection bias or differential participation rates due to both vasectomy status and a family history of prostate cancer. These results suggest no overall association between vasectomy and prostate cancer.

Adult↗
PubMed1996

Identification of N-acetylglucosamine binding residues in Griffonia simplicifolia lectin II.

Primary structure and crystallographic data of several legume lectins were used to predict the involvement in carbohydrate binding of six amino acid residues (Asp88, Glu108, Tyr134, Asn136, Leu226 and Gln227) in Griffonia simplicifolia lectin II (GS-II). The functional involvement of these residues was evaluated by assessing GlcNAc binding of modified forms of GS-II in which these residues were eliminated in truncated peptides or systematically substituted with other amino acids by site-specific mutations. Mutations at Asp88, Tyr134 or Asn136 eliminated GlcNAc binding activity by GS-II, while those at Glu108, Leu226 or Gln227 did not alter the activity. The former three amino acids were functionally essential for carbohydrate binding by GS-II presumably through hydrogen bonding to and hydrophobic interactions with GlcNAc. Although an Asp or Gly substitution for Tyr134 eliminated GlcNAc affinity, substitution with Phe did not appreciably affect binding. Despite the fact that mutations to Leu226 and Gln227 did not alter carbohydrate binding, a truncated form of GS-II lacking these residues no longer exhibited carbohydrate binding affinity.

Acetylglucosamine↗
PubMed1996

An insecticidal N-acetylglucosamine-specific lectin gene from Griffonia simplicifolia (Leguminosae).

Griffonia simplicifolia II, an N-acetylglucosamine-specific legume lectin, has insecticidal activity when fed to the cowpea weevil, Callosobruchus maculatus (F.). A cDNA clone encoding G. simplicifolia II was isolated from a leaf cDNA library, sequenced, and expressed in a bacterial expression system. The recombinant protein exhibited N-acetylglucosamine-binding and insecticidal activity against cowpea weevil, indicating that glycosylation and multimeric structure are not required for these properties. These results support the hypothesis that genes of the legume lectin gene family encode proteins that function in plant defense against herbivores.

Acetylglucosamine↗
PubMed1996

[A study on red blood cell immune function in patients with Guillain-Barré syndrome and multiple sclerosis].

In order to understand whether there is red blood cell (RBC) immune dysfunction and the relationship between RBC immune abnormality and clinical state in patients with multiple sclerosis (MS) and Guillain-Barré syndrome (GBS), RBC immune function and circulation immune complex (CIC) level were evaluated in patient with these two diseases by using RBC immune adhesion test. It was found that the rate of formation of red blood cell-C3b receptor-yeast rosette was significantly lower in patients with these two diseases before and after treatment than that in a control group (P < 0.01). The rate of formation of red blood cell-immune complex-yeast rosette and the CIC level in GBS group were notably higher than that in the control group (P < 0.05). Moreover, we observed that the immune functions in patients with severe GBS and active MS were different from those in patients with mild GBS and stable MS and the change of each immune index in GBS and MS patients was related with the degree of recovery and the clinical state. These results suggested that decreased capability of RBC immune adhesion in patients with GBC and MS may be one of factors causing these diseases.

Adolescent↗
PubMed1995

A population-based case-control study of the relationship between cigarette smoking and nasopharyngeal cancer (United States).

This case-control investigation, based on the Selected Cancers Study, assesses the association between cigarette smoking and nasopharyngeal cancer, a relatively rare neoplasm in the United States. Men who were diagnosed pathologically with nasopharyngeal cancer during 1984-88 were included as cases in the analysis if they were 15 to 39 years old in 1968, and lived in the areas covered by eight cancer registries in the US (n = 113). Control men were selected by random-digit telephone dialing (n = 1,910). Using logistic regression analysis with adjustment for potential confounding factors, it was found that relative to nonsmokers, the risks of nasopharyngeal cancer were 2.3 (95 percent confidence interval [CI] = 1.3-4.0) and 1.4 (CI = 0.8-2.6) for former and current smokers, respectively. Using pack-years as a measure, adjusted odds ratio (OR) estimates were 1.3, 1.8, 2.5, and 3.9 for smoking for less than 15, 15-29, 30-44, and 45 or more pack-years, respectively. When squamous cell carcinoma was used as an outcome, the smoking/nasopharyngeal-cancer association became stronger. The analysis did not show interactions between smoking and alcohol consumption, or prior nasal diseases. The results of this study suggest that cigarette smoking may be related to the occurrence of nasopharyngeal cancer (especially squamous cell carcinoma) among US men.

Adolescent↗