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Biomedical subjects

A Wang

Publications and source records attributed to A Wang.

At least 91 records · Page 5Linked to original sources
PubMed2000

Microdevices in medicine.

The application of microelectromechanical systems (MEMS) to medicine is described. Three types of biomedical devices are considered, including diagnostic microsystems, surgical microsystems, and therapeutic microsystems. The opportunities of MEMS miniaturization in these emerging disciplines are considered, with emphasis placed on the importance of the technology in providing a better outcome for the patient and a lower overall health care cost. Several case examples in each of these areas are described. Key aspects of MEMS technology as it is applied to these three areas are described, along with some of the fabrication challenges.

Biomedical Engineering↗
PubMed2000

Identification of the metabolites of roxithromycin in humans.

The semisynthetic antibiotic roxithromycin (RXM) exists in an (E)-configuration. Metabolites of RXM in the bile of four cholecystectomy patients with T-tube drainage and in the urine and plasma of four healthy volunteers after single oral doses of 150 mg of RXM were investigated. A total of 15 metabolites were found in bile, urine, and plasma by HPLC with ion trap mass spectrometric and electrochemical detection. These metabolites were identified as descladinose derivative of RXM (M1), erythromycin-oxime (M2), N-, O-, and N,O-di-demethylated derivatives of RXM (M3, M4, and M6), and N-mono- and N-di-demethylated derivatives of erythromycin-oxime (M5 and M7), as well as the (Z)-isomers (M8-M15) of RXM and metabolites M1 to M7, respectively. Structures of six major metabolites (M1-M4, M8, and M10) were established by chromatographic and mass spectrometric determination and comparison with synthesized standards. The stability of RXM and the six synthesized substances was investigated to exclude artifact products. These results, together with previous findings, suggest that biotransformation pathways elucidated for RXM include: 1) isomerization of RXM derivatives, from E-isomer to Z-isomer; 2) O-demethylation; 3) N-demethylation; 4) hydrolysis of the cladinose moiety; and 5) dealkylation of the oxime ether side chain. Secondary metabolism via these pathways was also evidenced. The O-demethylation and isomerization of RXM derivatives represent two novel biotransformation pathways recovered for RXM.

Adolescent↗
PubMed2000

The relationship between elution time and eluate volume using the Ultra-TechneKow DTE technetium-99m generator.

OBJECTIVE: The new Ultra-TechneKow Dry Ship Top Elute 99mTc generator (UTK-DTE generator; Mallinckrodt Medical, Inc., St. Louis, MO) was devised to facilitate fractionated elution with an ergonomically designed elution shield. Fractionation is accomplished traditionally by visually observing the eluted volume through 2 layers of leaded glass windows located in a lighted elution shield and generator auxiliary shield. The goal of our study was to use elution time to determine the endpoint for obtaining the required volume of 99mTc-eluate from a UTK-DTE generator. METHODS: After triplicate elution at several predetermined elution times, the initial weight of the evacuated collecting vial was subtracted from the total weight after elution to determine the elution volume. RESULTS: A quadratic relationship was established between the eluate volume (v, mL) and elution time (t, s) (v = 0.3594 + 0.1889 t - 0.0009 t2). This equation is suitable for use with the 10-mL elution vial. This formula may not be accurate for the first elution since the UTK-DTE generator is a dry-column generator when shipped. The following elution times were calculated for some commonly eluted volumes: 2 mL (9 s), 4 mL (22 s), 5 mL (28 s), 7 mL (45 s), and 10 mL (88 s). CONCLUSION: Our calculated elution time method can be used to predict the eluate volume from a UTK-DTE generator.

Algorithms↗
PubMed2000

[Long-term monitoring of artificial vagina reconstructed with sigmoid colon].

OBJECTIVE: To observe the influence of the artificial plastic vagina on overall patient health. METHODS: Length and width of the artificial vagina were measured. Histological studies were performed under light and electron microscope. Vaginal bacterial flora were analyzed using the drop-implant method. Vaginal HPV and ER were detected with ABC histochemical staining. RESULTS: According to the results of anatomic measurements, artificial vagina was similar to normal vagina. The reductions of glands in the mucosa and collagen fibers as well as interstitial tissue hyperplasia in the lower segment of artificial vagina were documented. Four kinds of bacteria indigenous to the sigmoid colon were found in artificial vagina and were studied microbiologically with only differences in the amount and detection rates of bacteria flora. The positive presentation of HPV was not significantly different from that in the control group. The positive presentation of estrogen receptor (ER) in the epithelium of artificial vagina was not found. CONCLUSION: The reconstruction of artificial vagina with sigmoid colon is a safe, effective and satisfactory procedure for the patient.

Adolescent↗
PubMed2000

[The diagnostic value of telomerase activity in bronchial biopsy specimen for lung cancer].

OBJECTIVE: To explore the diagnostic value of telomerase activity for lung cancer. METHODS: Telomerase activity was measured by PCR-TRAP in cancerous lesions and contralateral bronchial tissues from patients with lung cancer and in the bronchial tissues from patients with noncancerous pulmonary disorders, in which the tissue specimens were obtained by fiberoptic bronchoscopy. The result of telomerase detection was compared with the positive rates of pathologic study and bronchial brush cytology. RESULTS: The positive rate of telomerase activity in lesions of lung cancer was significantly higher than that in tissues of the contralateral bronchi from patients of lung cancer (P < 0.01) and that in tissues from patients of noncancerous pulmonary disorders (P < 0.01). There was no significant difference between the positive rate of telomerase activity expression and the positive rates of pathology and bronchial brush cytology (P > 0.05). CONCLUSION: Examination of telomerase activity was of significance in the diagnosis of lung cancer.

Biomarkers, Tumor↗
PubMed2000

[An observation of the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children].

OBJECTIVE: To study the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children. METHODS: Hemagglutination inhibition (HI) antibody detection method was used to test on children at age 6 to 18 months without rubella infection or rubella vaccine immunization in Yantai city of Shandong province and were selected for the observation of the immuno-persistence against the domestic BRD II strain rubella vaccine from 1995 to 1998. RESULTS: Positive rates of HI antibody among children of 6, 7, 8, 9, 12 and 18 month-old of inoculation were 94.44%, 97.22%, 96.67%, 100.00%, 100.00%, 100.00% and 93.10%, 93.55%, 96.77%, 96.97%, 100.00%, 100.00% (P > 0.05), in one or two years respectively. The geometric mean reverse titers (GMRTs) were about 50% lower than that after 1 month after 1 year. Similar results were found that after 2 years GMRTs was about 50% lower than that after 1 year of inoculation. There was highly significant difference on GMRTs of HI antibody between infants with 6 to 7 month-olds (29.89) and young children with 8 to 18 month-olds (53.00) after 2 years of inoculation (t = 3.58, P < 0.001). CONCLUSION: The immunization schedule at the first dose for BRD II strain rubella vaccine should be started when the child is 8 month old. For the second dose, the immunization schedule used in other developed countries should be referred adopted in China.

Antibodies, Viral↗
PubMed2000

[Study of platelet membrane glycoproteins and its fibrinogen binding reaction in patients with cerebral infarction and diabetes mellitus].

OBJECTIVE: To investigate the change of platelet membrane glycoproteins and its fibrinogen binding reaction in patients with cerebral infarction and type II diabetes mellitus (DM), and assess their value in the study of thrombosis and pro-thrombosis state. METHODS: By flow cytometry, the platelet glycoprotein (GP) I b, GP II b, GP III a, GP II b- III a complex and P-selectin expression as well as fibrinogen binding reaction were analyzed in 85 patients with type II DM and 28 with cerebral infarction, and compared with that in 30 normal subjects. RESULTS: The platelet membrane GP II b- III a complex, P-selectin expression and fibrinogen binding reaction were higher, while the platelet surface GP I b was lower in the patients with cerebral infarction and type II DM with vascular disease than those in normal group. The GP II b and GP III a were not significantly changed. There was no difference of these parameters between the type II DM without vascular disease patients and normal group. CONCLUSION: The platelet fibrinogen binding reaction, P-selectin and GP II b- III a complex expression were increased while the GP I b decreased in patients with cerebral infarction and type II DM with vascular disease.

Adult↗
PubMed2000

[Clinical study on effect of combined treatment with shenlong oral liquid and radiotherapy in treating nasopharyngeal carcinoma].

OBJECTIVE: To observe the effect of Shenlong Oral Liquid (SLOL) combined with radiotherapy in treating nasopharyngeal carcinoma (NPC). METHODS: Effects of the combination therapy, including clinical effect, changes of cellular immunity and side effects, in treating 60 NPC patients (treated group) were observed and compared with those of the other 60 patients treated with radiotherapy alone (control group). RESULTS: (1) The side effect of radiation in the treated group was lower than that in the control group significantly (P < 0.05); (2) The immediate regression rate of nasopharyngeal and neck tumor in the two groups was not different significantly (P > 0.05); (3) The doses for complete remission of nasopharyngeal and neck tumor in the treated group was lower than that in the control group (P < 0.01); (4) No change of T-lymphocyte subsets was found in the treated group after treatment, but in the control group, OKT3, OKT4 and OKT4/OKT8 ratio were markedly decreased (P < 0.05); (5) The survival rate in the treated group was higher than that in the control group, but without statistical significance (P = 0.0518). CONCLUSION: The combination therapy of NPC by SLOL and radiotherapy is able to reduce side effect of radiotherapy, improve the cellular immunity, reduce the dose of radiation for tumor remission and enhance the therapeutic effect of radiotherapy, it might raise the survival rate of NPC patients.

Adjuvants, Immunologic↗
PubMed2000

[Apoptosis of chondrocytes in cartilage].

OBJECTIVE: To observe apoptosis of chondrocytes in cartilage and arthritis. METHODS: Apoptosis was detected by light and electron microscope and DNA electrophoresis, while [Ca2+]i was detected by confocal laser scanning microscope. RESULTS: Cartilage cells from osteoarthritis (OA) and rheumatoid arthritis (RA) could be seen to undergo normal differentiation after cultured for 3 days under light or electron microscope, while some chondrocytes directly isolated without culturing could give early changes of apoptosis, and normal chondrocytes in vitro after treatment with IL-1, TNF-alpha also underwent apoptosis. IL-1, TNF-alpha could induce increase of [Ca2+]i in chondrocytes. CONCLUSIONS: Our data showed that apoptosis might present in the normal cartilage as well as in OA and RA cells. IL-1, TNF-alpha could induce apoptosis of chondrocytes and [Ca2+]i increase during apoptosis.

Animals↗
PubMed2000

[The diagnosis and treatment of Lyme disease: a report of six cases].

We retrospectively analyzed the clinical features, diagnosis, treatment, and prognosis of 6 cases of Lyme disease from November, 1994 to December, 1998. According to our report, doxycycline, penicillin, and ceftriaxone are effective drugs for Lyme disease. The shorter the disease course is, the better the treatment effect will be. Patients in phase III usually need repeated treatment.

Adolescent↗
PubMed1999

Rapid analysis of gene expression (RAGE) facilitates universal expression profiling.

Current techniques for analysis of gene expression either monitor one gene at a time, for example northern hybridization or RT-PCR methods, or are designed for the simultaneous analysis of thousands of genes, for example microarray hybridization or serial analysis of gene expression. To provide a flexible, intermediate scale alternative, a PCR-based method for the rapid analysis of gene expression has been developed which allows expression changes to be determined in either a directed search of known genes, or an undirected survey of unknown genes. A single set of reagents and reaction conditions allows analyses of most genes in any eukaryote. The method is useful for assaying on the order of tens to hundreds of genes in multiple samples. Control experiments indicate reliable detection of changes in gene expression 2-fold and greater, and sensitivity of detection better than 1 in 10 000. Analyses of over 400 genes in a mouse system transgenic for the E2F1 gene have identified several new downstream targets of E2F1, including Brca1 and Cdk7, in addition to several unidentified genes that are upregulated in the transgenic mice. Changes in expression of several genes related to apoptosis suggest a possible potentiation of apoptotic pathways in the transgenic keratinocytes.

Animals↗
PubMed1999

Characterization of the human and mouse unconventional myosin XV genes responsible for hereditary deafness DFNB3 and shaker 2.

Mutations in myosin XV are responsible for congenital profound deafness DFNB3 in humans and deafness and vestibular defects in shaker 2 mice. By combining direct cDNA analyses with a comparison of 95.2 kb of genomic DNA sequence from human chromosome 17p11.2 and 88.4 kb from the homologous region on mouse chromosome 11, we have determined the genomic and mRNA structures of the human (MYO15) and mouse (Myo15) myosin XV genes. Our results indicate that full-length myosin XV transcripts contain 66 exons, are >12 kb in length, and encode 365-kDa proteins that are unique among myosins in possessing very long approximately 1200-aa N-terminal extensions preceding their conserved motor domains. The tail regions of the myosin XV proteins contain two MyTH4 domains, two regions with similarity to the membrane attachment FERM domain, and a putative SH3 domain. Northern and dot blot analyses revealed that myosin XV is expressed in the pituitary gland in both humans and mice. Myosin XV transcripts were also observed by in situ hybridization within areas corresponding to the sensory epithelia of the cochlea and vestibular systems in the developing mouse inner ear. Immunostaining of adult mouse organ of Corti revealed that myosin XV protein is concentrated within the cuticular plate and stereocilia of cochlear sensory hair cells. These results indicate a likely role for myosin XV in the formation or maintenance of the unique actin-rich structures of inner ear sensory hair cells.

Alternative Splicing↗
PubMed1999

Down-regulation of the stathmin/Op18 and FKBP25 genes following p53 induction.

The p53 tumor suppressor protein can function as an activator and a repressor of gene transcription. Currently, the mechanism of transcriptional repression by p53 is poorly understood. To aid in clarifying this mechanism, we carried out studies designed to identify specific target genes that are down-regulated following p53 induction. Among the negative p53-response genes revealed by our screening protocols are those encoding stathmin (Op18), a tubulin-associated protein implicated in cell signaling pathways, and an FK506/rapamycin-binding protein, FKBP25. Stathmin and FKBP25 exhibit decreased expression in both human and murine immortalized and transformed cell lines following induction of wild-type p53 by several stimuli that result in DNA damage. Candidate p53-repressed genes such as these provide the necessary markers to delineate the mechanism and biological consequences of transcriptional repression mediated by p53.

Animals↗
PubMed1999

Aberrant metabolic sialylation of recombinant proteins expressed in Chinese hamster ovary cells in high productivity cultures.

The incorporation of sialic acid into therapeutic recombinant glycoprotein expressed in Chinese hamster ovary (CHO) cells during growth in large bioreactors (10 l) has been monitored under high productivity conditions induced by the presence of sodium butyrate. Samples of the bioreactor culture (approximately 4 x 10(6) cells) were labeled with 3H-N-acetylmannosamine, a metabolic precursor of sialic acid. After 24 h, the recombinant glycoprotein, an immunoadhesion chimeric molecule, was purified and the amount of sialic acid incorporated was determined as radioactive counts. The labeling profile of the protein over the course of the culture was compared with the sialic acid content of the molecule as determined by direct chemical analysis. Early in the culture, the two methods of analysis gave a similar sialylation profile. However, after sodium butyrate was included in the culture, the metabolically incorporated sialic acid rapidly and dramatically decreased to near undetectable levels. In contrast, sialic acid content of the protein, as determined by chemical analysis, decreased only moderately and gradually over the culture period, from a maximum of 6.1 to about 5. 0 mol sialic acid/mole of protein after 10 days in culture. These results suggest that butyrate may enhance reutilization of existing glycoproteins in the culture, generating sialic acid for biosynthesis through lysosomal degradation and thereby bypassing de novo biosynthesis.

Animals↗
PubMed1999

A specific human lysophospholipase: cDNA cloning, tissue distribution and kinetic characterization.

Lysophospholipases are critical enzymes that act on biological membranes to regulate the multifunctional lysophospholipids; increased levels of lysophospholipids are associated with a host of diseases. Herein we report the cDNA cloning of a human brain 25 kDa lysophospholipid-specific lysophospholipase (hLysoPLA). The enzyme (at both mRNA and protein levels) is widely distributed in tissues, but with quite different abundances. The hLysoPLA hydrolyzes lysophosphatidylcholine in both monomeric and micellar forms, and exhibits apparent cooperativity and surface dilution kinetics, but not interfacial activation. Detailed kinetic analysis indicates that the hLysoPLA binds first to the micellar surface and then to the substrate presented on the surface. The kinetic parameters associated with this surface dilution kinetic model are reported, and it is concluded that hLysoPLA has a single substrate binding site and a surface recognition site. The apparent cooperativity observed is likely due to the change of substrate presentation. In contrast to many non-specific lipolytic enzymes that exhibit lysophospholipase activity, hLysoPLA hydrolyzes only lysophospholipids and has no other significant enzymatic activity. Of special interest, hLysoPLA does not act on plasmenylcholine. Of the several inhibitors tested, only methyl arachidonyl fluorophosphonate (MAFP) potently and irreversibly inhibits the enzymatic activity. The inhibition by MAFP is consistent with the catalytic mechanism proposed for the enzyme - a serine hydrolase with a catalytic triad composed of Ser-119, Asp-174 and His-208.

Amino Acid Sequence↗