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Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 523 records · Page 29Linked to original sources
PubMed1976

Immunologic assessment of regional lymph node histology in relation to survival in head and neck carcinoma.

Histologic material from 84 cases of squamous cell carcinoma of head and neck regions was studied by double blind retrospective analysis. Sections of lymph nodes draining the tumors were examined microscopically to assess the morphologic pattern of response. Patients whose lymph nodes demonstrated active immunologic responses in the form of expanded inner cortices or increased numbers of germinal centers had 5-year survival rates significantly greater than those patients whose regional lymph nodes showed an unstimulated pattern. None of the patients whose lymph nodes showed the depleted pattern survived 5 years. These correlations were independent of the stage or grade of the tumor. Metastases occurred much more frequently in patients having regional nodes showing an unstimulated or depleted pattern than in those whose regional nodes showed evidence of immunologic activity. The data support the concept of a relationship between immunologic activity, progression of neoplasia, and survival. Morphologic assessment of immunologic activity in lymph nodes draining malignant tumors appear to be of significant value in the predicting survival.

Carcinoma, Squamous Cell↗
PubMed1976

Automated sleep EEG analysis applied to the evaluation of drugs: illustration by study of clorazepate dipotassium.

An automated sleep EEG analysis system was used to evaluate the effects of clorazepate dipotassium in normal subjects. Ten young-adult men slept 18 consecutive nights in the laboratory. On days 8-15 clorazepate (7.5 mg) was administered three times daily; on days 5-7 and 16-18 a placebo was administered in a similar fashion. The drug reduced amounts of alpha and delta activity and increased the amount of beta activity and the number of spindles. These effects generally persisted through the 3 day placebo recovery period. Our results suggest that sleep EEG waveform descriptors are sensitive indicators of drug activity and that beta activity in particular may be useful in the detailed description of various drug effects.

Adult↗
PubMed1976

Prognostic significance of lymph node histology in patients with squamous cell carcinoma of the larynx, pharynx, or oral cavity.

In a double-blind retrospective analysis, sections of lymph nodes regional to head and neck squamous cell carcinomas were microscopically examined to assess morphologically the immunologic pattern of response. Patients whose nodes showed evidence of immunologic stimulation had five-year survival rates significantly higher than those whose nodes showed no evidence of immunologic stimulation. None of the patients whose nodes showed the lymphocyte depletion pattern survived five years. The stage or histologic grade of the tumors did not influence these correlations. Metastases occurred much more frequently in patients whose nodes showed immunologic activity than in those whose did not. The data support the concept that immunologic capacities are important host defense mechanisms against malignancy. Histologic assessment of immunologic activity in regional nodes seems to be an important parameter for predicting survival.

Adult↗
PubMedDate not supplied

School physical education: effect of the Child and Adolescent Trial for Cardiovascular Health.

BACKGROUND: Physical inactivity is a risk behavior for cardiovascular and other diseases. Schools can promote public health objectives by increasing physical activity among youth. METHODS: The Child and Adolescent Trial for Cardiovascular Health (CATCH) was a multicenter, randomized trial to test the effectiveness of a cardiovascular health promotion program in 96 public schools in four states. A major component of CATCH was an innovative, health-related physical education (P+) program. For 2.5 years, randomly assigned schools received a standardized PE intervention, including curriculum, staff development, and follow-up. RESULTS: Systematic analysis of 2,096 PE lessons indicated students engaged in more moderate-to-vigorous physical activity (MVPA) in intervention than in control schools (P = 0.002). MVPA during lessons in intervention schools increased from 37.4% at baseline to 51.9%, thereby meeting the established Year 2000 objective of 50%. Intervention children reported 12 more min of daily vigorous physical activity (P = 0.003) and ran 18.6 yards more than control children on a 9-min run test of fitness (P = 0.21). CONCLUSIONS: The implementation of a standardized curriculum and staff development program increased children's MVPA in existing school PE classes in four geographic and ethnically diverse communities. CATCH PE provides a tested model for improving physical education in American schools.

Adolescent↗
PubMedDate not supplied

The effects of the Child and Adolescent Trial for Cardiovascular Health upon psychosocial determinants of diet and physical activity behavior.

BACKGROUND: The Child and Adolescent Trial for Cardiovascular Health is a multisite study of a school-based intervention to reduce or prevent the development of risk factors for cardiovascular disease. The purpose of this paper is to present the evaluation results of the 3-year intervention, focusing upon the psychosocial variables conceptualized as determinants of dietary and physical activity behaviors. METHODS: A total of 96 schools across four study sites (California, Louisiana, Minnesota, and Texas) were randomized to two treatment conditions: intervention and control. Pre- and postmeasurements on the health behavior questionnaire were collected from over 6,000 students. The data analyses utilized a nested design approach in which schools served as the primary unit of analysis. Repeated-measures multivariate analyses were applied to investigate effect sizes for each determinant and to explore theoretical relationships among the determinants over time. RESULTS: The findings indicated sustained significant effects in improved knowledge, intentions, self-efficacy, usual behavior, and perceived social reinforcement for healthy food choices (P < 0.0001 for these five variables) after 3 years. Intermittent effects were observed for perceived support and self-efficacy for physical activity. No gender by determinant interaction effects were observed, and girls reported significantly greater perceived reinforcement for healthy eating than did boys. CONCLUSION: The CATCH program was effective in changing the psychosocial variables likely to influence a reduction in behavior for cardiovascular disease. The study is significant in that it demonstrates the viability and effectiveness of a sustained multifaceted intervention in a preadolescent population. The results point to a need for greater understanding of adolescent developmental issues and the role of community environment (particularly social support) in creating effective curricula.

Adolescent↗
PubMedDate not supplied

Tobacco use measurement, prediction, and intervention in elementary schools in four states: the CATCH Study.

BACKGROUND: The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multistate field trial examining the effects of school environment, classroom curricula, and family intervention components in promoting the cardiovascular health of elementary school students. The purpose of this paper is to describe the CATCH tobacco use intervention and measurement, including the adoption of tobacco-free school policies. METHODS: In this study, changes in school tobacco use policies and smoking experimentation among students were assessed. Smoking experimentation was measured in all CATCH schools when the students were in their fifth-grade year. A total of 6,527 subjects in 96 schools in California, Louisiana, Minnesota, and Texas answered questions about behaviors and potential correlates of smoking as part of the CATCH health behavior questionnaire in Spring 1994. School tobacco use policy, an important complement to classroom- and home-based prevention efforts, was promoted as part of the CATCH intervention. The degree to which such policy was implemented was measured using surveys of school officials. RESULTS: At the end of fifth grade, only 4.8% of the subjects indicated that they had experimented with tobacco. School intervention condition was not a factor in the prediction of experimentation. Those whose best friend or sibling smoked, or who had ready access to cigarettes in the home, were more likely to have experimented with smoking. In the 3 years of the study, the percentages of tobacco-free schools went up from 49.7 to 76.8%. Though differences in the rate of policy adoption could not be directly attributed to the CATCH intervention, the implementation of the tobacco-free schools' policies did vary substantially from state to state. Minnesota and Texas, with stronger state laws supporting local policy, had nearly completely smoke-free schools. In spite of a statewide tobacco control initiative, California was slower to implement school policies. Louisiana, which allows local decision making regarding smoking policy, had the most difficulty establishing a policy for all districts. CONCLUSION: Future studies should examine the impact of parallel policy interventions that are ongoing at both school and state levels. Tobacco-free policies appear to be a crucial part of school-based interventions and must be tailored to political and regional factors affecting a given school district.

Adolescent↗
PubMedDate not supplied

Double-stranded cyclic oligonucleotides with non-nucleotide bridges.

A series of double-stranded, cyclic oligodeoxynucleotides with non-nucleotide bridges have been synthesized, and their physicochemical properties and susceptibility to enzymes have been investigated. These bridged duplexes are of potential interest for their binding properties to transcription factors and other DNA-binding proteins. Triethylene glycol has been employed as the bridge to alter the lipophilicity of the duplex and avoid the potential for enzymatic cleavage. The synthetic route involved the synthesis of a 3'-phosphorylated, nicked double-stranded precursor with the final internucleotide bond being formed chemically using a water soluble carbodiimide. These bridged duplexes have high thermal dissociation temperatures, and the Tm for a triethylene-bridged 20 base pair duplex was higher than that for the corresponding pentathymidylate-bridged duplex. EcoR I endonuclease cleaved a ligated, bridged duplex at a slower rate than the corresponding unmodified duplex, whereas the unligated, bridged duplex was cleaved more rapidly. Sufficient amounts of the bridged octamer and dodecamer were prepared for proton NMR spectroscopic studies, and 2D COSY and NOESY spectra were obtained. The results indicate that the ligated duplex has a B-form conformation.

Base Sequence↗
PubMedDate not supplied

Effect of ammonia on the glycosylation of human recombinant erythropoietin in culture.

Recombinant human erythropoietin (EPO) was produced by a stable transfected CHO-K1 cell clone (EPO-81) grown in serum-free medium. Our previous work showed that there was a significant increase in the heterogeneity of the glycoforms of EPO and a reduction of the sialylation at 20 mM NH(4)Cl. In the work presented here, the effects of ammonia on EPO N-linked oligosaccharides were analyzed. EPO was purified from culture supernatants by immunoaffinity chromatography. The N-linked oligosaccharides were released enzymatically and analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and HPLC. The FACE N-linked oligosaccharide profile showed that the sialylated glycans contain one prominent band at a position corresponding to eight glucose units. The density of the major band was greatly diminished and the width was significantly increased in cultures containing added ammonia. The proportion of tetraantennary structures was reduced by 60%, while the tri- and biantennary structures were increased proportionally in the presence of ammonia. Glycan analysis by HPLC using a weak anion exchange column showed that the most significant characteristic effect of ammonia was a reduction of the proportion of glycans with four sialic acids from 46% in control cultures to 29% in ammonia-treated cultures. Analysis of the desialylated glycans by normal phase chromatography indicated a distribution of tetra-, tri-, and biantennary structures similar to that shown by FACE. The N-linked glycan sequence was determined by sequential exoglycosidase digestion followed by FACE. The results indicated a typical N-linked complex oligosaccharide structure. Glycans from ammonia-containing cultures showed the same sequence pattern. In conclusion, we showed that ammonia in the culture medium affected EPO glycosylation, which was observed as a reduction of the tetraantennary and tetrasialylated oligosaccharide structures. However, the presence of ammonia in the cultures did not change the oligosaccharide sequence.

Ammonia↗
PubMedDate not supplied

Effects of ammonia and glucosamine on the heterogeneity of erythropoietin glycoforms.

Recombinant human erythropoietin (EPO) is a glycoprotein produced as a therapeutic agent from mammalian cell cultures for the treatment of anemia associated with severe kidney damage. The EPO structure has a high glycan content which is essential for bioactivity but shows considerable molecular heterogeneity. The cell culture conditions that affect the heterogeneity of the glycoforms of EPO are not well understood. However, the accumulation of ammonia in culture is one factor that has been associated with an enhanced heterogeneity of glycoforms. In this report we investigate the metabolic perturbations associated with ammonia and glucosamine that may give rise to an altered pattern of EPO glycosylation. Recombinant human erythropoietin was synthesized in serum-free cultures of transfected Chinese hamster ovary (CHO) cells. The molecular heterogeneity of erythropoietin was increased by supplementation of cultures with either ammonia or glucosamine. The enhanced molecular heterogeneity was shown to be due to variable glycosylation that resulted in EPO with an enhanced molecular weight and isoelectric point range. Enzymatic removal of the glycan moiety of EPO in all cases resulted in a single molecular form with a molecular weight of 18 000, which corresponded to non-glycosylated EPO. The variable glycosylation was consistent with reduced sialylation and antennarity of the carbohydrate structures present on the three N-linked sites of EPO. In the presence of ammonia (>30 mM) the proportion of tetrasialylated and tetraantennary glycan structures were reduced by 73% and 57%, respectively, as determined by HPLC analysis. Such changes were also observed, although to a lesser extent (41% and 37%), by an increase in the glucosamine concentration (>10 mM) in the medium. The enhanced heterogeneity of the glycan structures coincided with a significant increase in the intracellular UDP-N-acetylhexosamine (UDP-GNAc) pool. The measured UDP-GNAc level was up to 2 orders of magnitude higher in the presence of either glucosamine or ammonia. However, the changes in the glycosylation profiles induced by either glucosamine or ammonia were significantly different even at the same intracellular UDP-GNAc concentration. This suggests that the enhanced EPO heterogeneity could not be mediated solely by the increased UDP-GNAc level. Glucosamine (but not ammonia) was shown to cause significant inhibition of glucose transport into the cells, which could induce a different pattern of primary metabolism.

Ammonia↗
PubMedDate not supplied

Hydrogen sulfide inhalation injury.

Hydrogen sulfide is a colorless, noxious gas with the distinctive smell of rotten eggs. This compound is a powerful reducing agent that is encountered in a number of industrial processes. When hydrogen sulfide is present, it exposes workers to the potentially lethal effects of the rapid hypoxemia that results from exposure to this agent. The "warning sign" is the characteristic smell of rotten eggs; this smell should alert anyone in the area that a potentially serious risk exists. The immediate removal of the victim and administration of high-flow oxygen is essential. Neurologic sequelae may require anticonvulsants and care must be exercised to observe for cardiac, hepatic, and renal insufficiency. Depending on the concentration, hydrogen sulfide can rapidly overcome a potential victim.

Adult↗
PubMedDate not supplied

Weight and length growth of two Chinese infant groups and the seasonal effects on their growth.

This is a longitudinal study involving 202 Chinese infants in Chengdu City and 174 Hong Kong infants in their first two years of life. Their weight and length growth are compared, and the seasonal effects on the early age growth for the two groups are illustrated by using a multilevel model approach. The Chengdu infants are found to grow faster in the first 10 months, then stay longer, heavier and fatter for the rest of the study period. The seasonal effect on weight growth for the two groups is the same with the fastest growth in winter and slowest in summer and with a mean difference of about 0.16 kg. For length the fastest is in summer for Chengdu infants but in winter for Hong Kong infants. The difference between the slowest and fastest is about 0.49 cm for the two groups. The approach used in the paper is discussed from a practical viewpoint. The reasons for the growth differences between the two groups of Chinese infants are also discussed.

Body Height↗
PubMedDate not supplied

A capillary method to measure water transmission through polyurethane membranes.

A capillary method has been developed to measure the rate of water transmission through polyurethane membranes prepared for use as ventricles in artificial hearts. The system consisted primarily of a leak-proof sample chamber containing the water, a glass capillary flow meter, and a receiver compartment with continuous dry air ventilation. The capillary flow meter monitored the volume of water loss in the sample chamber. The rate of water transmission through the test membrane was found to be proportional to the water loss in the sample chamber, and dependent on the membrane thickness. For thicknesses from 0.09 mm to 0.34 mm, water vapor transmission rates ranged from 7.53 x 10(-8) to 2.76 x 10(-8) mol/s cm2, respectively. Although the concentration of water vapor in the receiver compartment did affect the rate of water vapor transmission through the membrane, within the pressure range 50-200 mmHg, there was very little effect. These findings suggest that water transmission through a polyurethane membrane is dominated by a diffusion process rather than by bulk convection.

Biocompatible Materials↗
PubMedDate not supplied

Identification of pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation using MRI.

Pulmonary vein stenosis is one of the frequent complications after radiofrequency ablation for atrial fibrillation. MRI plays an important role in depicting the pathoanatomic structure of the pulmonary veins, and measuring the blood flow velocity in the pulmonary veins before and after therapy, and is superior to transesophageal echocardiography for this purpose.

Aged↗
PubMedDate not supplied

Effects of flt-3 ligand in combination with TPO on the expansion of megakaryocytic progenitors.

As an early acting growth factor, flt-3 ligand (FL) promotes the ex vivo expansion of hematopoietic stem and progenitor cells. The effect and mechanism of FL on the development of the megakaryocytic lineage remain unclear. In this study, we compared the effects of FL and stem cell factor (SCF) in combination with other megakaryocyte-promoting cytokines on the differentiation and proliferation of megakaryocytic progenitors and investigated the expression of flt-3 receptors on megakaryocytic cell lines. In liquid cultures of enriched CD34+ cells from human umbilical cord blood for 14 days, FL plus thrombopoietin (TPO), interleukin-3 (IL-3), and IL-6 promoted the expansion of nucleated cells, CD34+ cells, CD34+ CD38- cells, and megakaryocyte colony-forming units (CFU-MK) by 300 +/- 115-, 23.8 +/- 11.3-, 33.9 +/- 28.6-, and 584 +/- 220-fold, respectively. Replacing FL with SCF significantly decreased the yield of all cell types. Using murine bone marrow (BM) cells, we demonstrated that FL at a range of 0-100 ng/ml had no significant mitogenic effect on CFU-MK formation. TPO increased CFU-MK (p < 0.001) but the effect was not significantly modified by FL. While one human acute lymphoblastic leukemia sample expressed high levels of flt-3 receptor, the four megakaryocytic cell lines (Meg-01, CHRF-288-11, M-07e, and Dami) did not show any positive expression. Our data suggest that the present cytokine combination and expansion conditions provide an effective and potentially useful system for the clinical expansion of cord blood for bone marrow transplantation (BMT). FL alone did not stimulate megakaryocytopoiesis, possibly due to the lack of receptor expression on megakaryocytes. The effect of FL in augmenting the expansion of CFU-MK in liquid culture might be due to the early action of FL at the pluripotent stem cell stage.

Adjuvants, Immunologic↗