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Biomedical subjects

Z Shen

Publications and source records attributed to Z Shen.

At least 289 records · Page 16Linked to original sources

Attitudes of Colorado health professionals toward breast and cervical cancer screening in Hispanic women.

BACKGROUND: A variety of economic, cultural, and communication barriers appear to be involved in breast and cervical cancer screening among Hispanic women. These barriers include culture-based embarrassment both for mammography and for Pap smears and fear and hopelessness concerning a diagnosis of cancer. Cost and access barriers are shared by low-income women from various ethnic and racial groups, as is a purported lack of physician referral. Hispanic women may have the latter problem enhanced by a language barrier between physicians and patients when the physicians do not speak or understand Spanish. PURPOSE: The goal of this project, conducted by the Cancer Education Division of the University of Colorado Cancer Center, has been to determine the attitudes and practices among health care providers in areas of Colorado with relatively large Hispanic populations (concerning screening mammography, clinical breast examination, breast self-examination, and Pap testing) and to design interventions to address any deficiencies or problems recognized. These studies were coordinated with telephone surveys and focus groups involving Hispanic women, directed by E. Flores in the Department of Sociology of the University of Colorado at Boulder and by C. Chrvala at the Colorado Department of Health. METHODS: Data were collected from 520 primary care physicians, nurses, and allied health personnel in 11 Colorado counties through focus groups and mailed questionnaires. Responses were analyzed by considering a variety of demographic characteristics of the respondents and by stratifying the associated practices by percent of Hispanic patients. RESULTS: The physicians involved in the focus groups and responding to the questionnaires, as well as their associated nurses and other health care personnel, are generally familiar with the breast and cervical cancer-screening guidelines as developed and disseminated by several organizations, including the National Cancer Institute and the American Cancer Society. Major barriers to screening Hispanic women, as perceived by these health care providers, appear to be cost; lack of transportation, child care, and release from work; fear of diagnosis of cancer; patients considering the test unnecessary; discomfort; and embarrassment. The prompt use of colposcopy to evaluate patients whose Pap smears indicated dysplasia appeared less than optimal, especially among internists. CONCLUSIONS: Familiarity with guidelines for breast and cervical cancer screening is widespread among Colorado physicians and associated health care personnel, including those with high percentages of Hispanic patients in their practices. Increased continuing education efforts may be indicated concerning the application of colposcopy to the evaluation of women with abnormal Pap smears and concerning the application of computer technology to cancer-screening reminder systems. IMPLICATIONS: Educational approaches to primary care professionals may improve the effectiveness of breast and cervical cancer screening, although a variety of other approaches will also be necessary to decrease barriers to screening of Hispanic women.

Adult↗

[Treatment of burned joints and functional recovery].

From 1979 to 1990, 33 operations on 29 patients with joint burn were performed by early debridement and primary repair with myocutaneous flaps. As a result, 29 wounds healed by first intention. The healing rate of early operations performed within 10 days postburn was 95.2%, and that of the late operations delayed more than 10 days post-burn was only 75.0%. 31 among 33 joints (93.9%) recovered full range of movement, while the other 2 joints ended with only slight limitation of function. We suggest that the early debridement and primary repair with myocutaneous flap is the best choice for treatment of burned bone and joints.

Adolescent↗

[Expression of the retinoic acid nuclear receptors and retinoid X receptor gene in human breast cancer].

A number of studies have shown that retinoids can inhibit malignant cell growth including certain breast carcinoma cells. Its inhibitory effect is observed only in ER positive but not in ER negative breast cancer cells. We examined retinoic acid nuclear receptors (RARs) and retinoids X receptors (RXRs) levels in 6 breast carcinoma cell lines and 18 breast cancer biopsy specimens. We found that RAR-alpha mRNA level was significantly higher in ER positive cell lines and samples. RAR-gamma mRNA was expressed at relatively high levels in majority of tumor samples independent of the ER-status while RAR-beta mRNA was expressed at low levels. We also found high RXR-alpha mRNA levels in all of the tumor samples examined while RXR-gamma mRNA could not be detected. Our study suggests a possibility that retinoids inhibit tumor cell growth through RAR-alpha and RAR-alpha levels may serve as a potential marker to determine responsiveness of patients to retinoids therapy.

Breast Neoplasms↗

[Serogroups, virulence and hemolytic activity of Aeromon as hydrophila which caused fish bacterial septicaemia].

A new infected disease called bacterial septicaemia occurred in cyprinid fish throughout China during 1989-1992. A. hydrophila was known as the most important pathogen of this harmful disease. Thirty-three strains of A. hydrophila, most isolated from moribund fishes, were serogrouped by tube-agglutination with rabbit antisera. Most of the isolates could be grouped into two serotypes, TPS-30 and PBJS-76. These two groups could be found not only in Zhejiang province but in other province in south China. It can be concluded that the two serogroups were the main Aeromonas groups caused this fish disease. These isolates were virulent to Carassius auratus, with LD50 values of 10(4) to 10(6). The hemolytic activity ranged from titers of 1/8 to 1/16. No relationship were observed with the hemolytic activity and virulence.

Aeromonas hydrophila↗

Effects of specific fatty acid acylation of phospholipase A2 on its interfacial binding and catalysis.

Monomeric phospholipase A2 (PLA2) from the venom of Agkistrodon piscivorus piscivorus (App-D49) was treated with 3-acyloxy-4-nitrobenzoic acids to acylate the epsilon-amino groups of two lysines (Lys-7 and Lys-10) in the amino terminal region. Resulting 7,10-diacylated-App-D49s, with acyl groups ranging from lauroyl to palmitoyl, spontaneously aggregated in solution. By contrast, 7,10-dioctanoyl-App-D49 existed as a monomer under the same condition. Kinetic and interfacial binding properties of diacylated enzymes indicated that they catalyzed the hydrolysis at the interface as a monomer. When compared to nonacylated App-D49, diacylated enzymes showed slightly increased activity or decreased activity toward monodispersed 1,2-dibutyryl-sn-glycero-3-phosphocholine, Triton X-100/1,2-dilauroyl-sn-glycero-3-phosphocholine mixed micelles, and small unilamellar vesicles (SUV) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Toward densely-packed liquid-crystalline phospholipid bilayers, such as large unilamellar vesicles (LUV) of POPC, however, diacylated enzymes exhibited a large increase in activity, which reacted up to 250-fold for 7,10-dilauroyl-App-D49 ((kcat/Km)app = (1.0 +/- 0.02) x 10(6) M-1 s-1). Measurements of the penetration of individual diacylated enzymes into 2-oleoyl-3-palmitoyl-sn-glycero-1-phosphocholine (i.e., D-POPC) monolayers indicated that the acyl groups enhanced the interfacial binding of protein by interacting with hydrocarbon moieties of phospholipids and that these hydrophobic interactions remained effective even when the phospholipid packing density was high. Furthermore, fluorometric measurements of the binding of diacylated enzymes to polymerized vesicles of 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphocholine showed that the hydrophobic interactions increased the enzymatic activity toward LUV by accelerating the migration of enzyme molecules to vesicle surfaces. The analysis of the kinetic course of POPC LUV hydrolysis showed that diacylated enzymes as a catalyst were superior to nonacylated App-D49 in that they were not only more catalytically efficient but also able to catalyze more turnovers without being trapped in product-containing vesicles. In summary, the acylation of App-D49 by 3-acyloxy-4-nitrobenzoic acids provides a simple and convenient way of converting the enzyme into a highly active form toward densely-packed liquid-crystalline phospholipid bilayers, which might have potential industrial and biomedical applications.

Acylation↗

Conformation of the central, three-helix junction of the 5 S ribosomal RNA of Sulfolobus acidocaldarius.

The current investigation has focused on the structure of the central, three-helix junction of the 5 S ribosomal RNA from Sulfolobus acidocaldarius, a thermoacidophilic archaebacterium. The 5 S molecule from S. acidocaldarius represents a paradigm for the study of the 5 S junction (and branched RNA structures in general) due to its unusually high degree of predicted secondary structure and stability. In order to study the junction in isolation, a set of three RNA heteroduplex molecules was assembled in which pairs of helices bounding the junction were extended by 70 base-pairs per helix. Since the extended helices comprise more than 95% of the heteroduplex structure, the relative solution conformations of the heteroduplex molecules, in effect, "report" the interhelix (branch) angles bounded by the extended pairs of helices. Examination of these heteroduplex molecules, using a combination of gel electrophoresis and transient electric birefringence measurements, has revealed a tertiary structure for the central branch in which helices I and V are essentially collinear, and in which helix II is relatively free to reorient with respect to the I-V axis.

Base Sequence↗

Enhanced cytochrome P450 (Cyp1b1) expression, aryl hydrocarbon hydroxylase activity, cytotoxicity, and transformation of C3H 10T1/2 cells by dimethylbenz(a)anthracene in conditioned medium.

The basal and benz(a)anthracene-induced aryl hydrocarbon hydroxylase activities of C3H 10T1/2 mouse embryo fibroblasts have been shown to vary with population growth. We report here that, in the case of dimethylbenz(a)anthracene, cytotoxicity and transformation (neoplastic/morphological transformation and focus formation) increased as a consequence of population growth and, at high cell densities, DNA adduct formation was elevated. Among the factors that may contribute to these changes, we have found that conditioning of the medium with population growth plays a significant role. Cells treated with medium conditioned by several days of cell growth supported increases in the dimethylbenz(a)anthracene induction of mRNA expression of a new mouse cytochrome P450 gene designated Cyp1b1, aryl hydrocarbon hydroxylase activity, cytotoxicity, and the frequency of neoplastic transformation. These results suggest a cause and effect relationship between the enhanced expression of Cyp1b1 due to medium conditioning and the enhanced expression of the cellular endpoints cytotoxicity and transformation.

9,10-Dimethyl-1,2-benzanthracene↗

Immunocytochemical evidence for chromogranin A and B in neuronal elements in human gut.

Chromogranins are a family of acidic proteins known to occur in the secretory granules of endocrine cells and neurons in mammals. The aim of the present study was to investigate the possible neuronal localisation of chromogranins in human intestine and their relationship with other neuronal constituents using one antibody recognizing both chromogranin A and B (CAB) and others recognizing only chromogranin A. Immunoreactive CAB was found to occur in mucosal endocrine cells and in neuronal elements of all layers throughout human gut. A few to large number of CAB-immunoreactive nerve fibers were seen in smooth muscles as well as in submucous and myenteric ganglia and they were regularly found around blood vessels. Occasional CAB immunoreactive nerve cell bodies could be demonstrated in both submucous and myenteric ganglia indicating a local origin of some of the immunoreactive fibers. Most of these neurons seemed to lack acetylcholine esterase, and could be classified as non-cholinergic. CAB coexisted with the catecholamine-synthesizing enzyme tyrosine hydroxylase indicating the presence of chromogranins in noradrenergic nerve fibers. The presence of CAB-immunoreactive nerve cell bodies indicates that some CAB-containing fibers are intrinsic in origin. The distribution of chromogranin A and B immunoreactive nerve fibers in all layers of the gut wall suggests multiple targets for neuronal CAB, and/or their processing products.

Acetylcholinesterase↗

Correlations among tyrosine phosphorylation of Shc, p72syk, PLC-gamma 1, and [Ca2+]i flux in Fc gamma RIIA signaling.

Tyrosine phosphorylation plays a critical role in Fc gamma RIIA signaling. In a mouse macrophage cell line transfected with human Fc gamma RIIA, cross-linking Fc gamma RIIA led to the transient generation of inositol 1, 4, 5-trisphosphate (IP3), [Ca2+]i flux, and rapid tyrosine phosphorylation of cellular substrates, including Shc, PLC-gamma 1, and a tyrosine kinase p72syk. In addition, tyrosine phosphorylated Fc gamma RIIA was co-precipitated with activated PLC-gamma 1. In contrast, no tyrosine phosphorylation of Shc or PLC-gamma 1 was detected in cells transfected with mutant receptors that failed to trigger [Ca2+]i flux. PMA inhibits both tyrosine phosphorylation of Shc and IP3 production leading to [Ca2+]i flux. However, PMA does not affect tyrosine phosphorylation of PLC-gamma 1 and p72syk. These results suggest that tyrosine phosphorylation of Shc and PLC-gamma 1 is important for the initiation of [Ca2+]i flux, and that activation of protein kinase C may modulate the activity of PLC-gamma 1 through serine/threonine phosphorylation.

Amino Acid Sequence↗

Reconstruction of refractory defect of scalp and skull using microsurgical free flap transfer.

Ten patients--six with acute burns, two with old accident or surgical trauma, and two with cranial carcinoma--experienced extensive full-thickness necrosis of the scalp and necrosis or defect of underlying skull bone. Microsurgical free flaps were used for the repair. Four latissimus dorsi, two rectus abdominis, one greater omentum, one prefabricated omentum-cutaneous flap, and two vascularized outer-table of the cranial bone flaps were used with complete survival. The heat-devitalized cranial bone covered by living tissue flaps healed well and substantial "regeneration" of previously necrosed bone was shown by roentgenogram, bone scan, and histopathological examination in the postoperative follow-up. Choosing an artery with high perfusion, bypassing from the carotid artery to support a massive free flap, is recommended.

Adolescent↗

Fc receptor-mediated signal transduction.

Receptors for the Fc domain of IgG (Fc gamma Rs) on leukocytes mediate a pleiotropic response following cross-linking by immune complexes. Signaling events following cross-linking of B and T cell antigen receptors, Fc epsilon RI, and Fc gamma Rs share common elements. In each, signaling is initiated by receptor cross-linking by antigen or immune complexes and results in the activation of src family kinases and ZAP-70-related tyrosine kinases, which associate with members of the receptor complex. Subsequent events include phosphorylation on tyrosine of multiple cellular substrates including phospholipase C gamma 1 and PI3-kinase. The [Ca2+]i flux is an event secondary to phospholipase C gamma 1 activation. Protein tyrosine kinase inhibitors block both early events such as [Ca2+]i flux and the later effects of cytokine release and cellular proliferation.

Amino Acid Sequence↗

Development of tolerance to experimental cardiac allografts in utero.

"Actively acquired tolerance" to foreign cells was described in 1953 by Medawar and colleagues and formed the basis for subsequent efforts in organ transplantation. We have applied these historic principles of intrauterine immune manipulation in a vascularized cardiac allograft model. Allogeneic Lewis-Brown Norway (LBN) splenocytes (0 to 5 x 10(7) cells) were injected intraperitoneally into each fetus of a pregnant Lewis rat at day 14 to 16 of gestation, when T cells are "educated" to distinguish self from foreign. This manipulation causes fetal attrition inversely proportional to the number of cells injected. Heterotopic transplantation using an LBN heart was carried out in each surviving fetus at 6 to 8 weeks of age. Untreated Lewis rats rejected LBN hearts within 7.6 days. Rats receiving LBN splenocytes in utero demonstrated prolongation of graft survival proportional to the number of cells given. Surviving animals exposed to 5 x 10(7) allogeneic cells in utero (n = 4) had graft survivals of 24 to more than 150 days (mean, 88.0 days), significantly longer than control animals (6 to 10 days; mean, 7.6 days; p < 0.02). Significant prolongation of cardiac allograft survival and in some cases complete tolerance can be achieved by intrauterine exposure to allogeneic cells at a critical period of immunologic development. Because many serious cardiac defects amenable to treatment by cardiac transplantation can be detected by ultrasound early in gestation, treatment based on this strategy may become useful in pediatric heart transplantation.

Animals↗