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Biomedical subjects

M S Chen

Publications and source records attributed to M S Chen.

At least 163 records · Page 9Linked to original sources
PubMed1987

Bimodal initiation of smokeless tobacco usage: implications for cancer education.

One hundred fifty (150) randomly chosen adult male subjects (average age 37) drawn from a university general dental clinic were classified by self-report into three equal categories of fifty smokeless tobacco users, fifty cigarette smokers (non-smokeless tobacco users), and fifty non-tobacco users. According to questionnaire results, a bimodal curve was exhibited among smokeless tobacco users with the two peaks of initiation at ages 12 and 18 compared to a unimodal age of initiation for cigarette smokers at age 16. Two different cohorts of smokeless tobacco users based on age of initiation were observed with differences reported in level of education, urban versus rural origin, average length of time in using smokeless tobacco, and the type of smokeless tobacco product used. Young initiators appeared to be primarily from rural communities having a strong parental or familial influence when initiating smokeless tobacco usage, whereas older initiators appeared to be primarily from more urbanized regions with peer influences as the most significant for initiating smokeless tobacco usage. Other characteristics associated with one or the other cohort were also reported, pointing to different educational measures that may be necessary for prevention and intervention, based on the age of initiating smokeless tobacco usage, as well as place of residence.

Adult↗
PubMed1987

An analysis of print and audiovisual materials to prevent smokeless tobacco use.

We analyzed 28 examples of smokeless tobacco educational print and audiovisual materials based on two criteria: (1) strength of the scientific bases for the selected materials, and (2) appropriateness of the materials for the known populations at risk to smokeless tobacco ever-use. We concluded that these materials in general are authoritative and provide the cancer educator with a solid scientific basis to initiate a primary prevention strategy. Nonetheless, some updating of materials to include the latest scientific findings (eg, cardiovascular and physiological/addictive effects) is needed. In terms of appropriateness of materials, we noted that the focus of materials was correctly targeted to young, white males; however, most materials tended to be aimed at seventh grade and beyond reading and social levels. Few, if any, materials were aimed at the other group at risk to smokeless tobacco adoption, namely youth in the early elementary grades. Consequently, while smokeless tobacco educational materials are generally authoritative, the cancer educator must still customize both the selection of materials and the educational approach to populations at risk.

Audiovisual Aids↗
PubMed1987

Ascorbic acid metabolism in diabetes mellitus.

Competition for membrane transport between glucose and ascorbic acid (AA) has been shown in vitro in human lymphocytes, granulocytes, and fibroblasts. Therefore, we examined the effects of acute administration of i.v. glucose on AA levels in mononuclear (MNL) and polymorphonuclear leukocytes (PMN) and on leukocyte chemotaxis. Plasma glucose and AA, MNL AA, PMN AA, and chemotaxis by MNL and PMN were measured before and after i.v. glucose in fasted normal male volunteers. A decline in AA occurred in PMN as well as MNL, but decreases in AA induced acutely by transient hyperglycemia were not associated with changes in chemotaxis. However, under conditions of prolonged hyperglycemia maintained by a glucose clamp technique, significant changes (p less than 0.01) in chemotaxis by both PMN and MNL were observed after 210 and 240 min, with changes in chemotaxis to several chemoattractants significantly correlated with decreases in intracellular AA after 240 min (p less than 0.05). These results are consistent with the hypothesis that chronic hyperglycemia may be associated with intracellular deficits of leukocyte AA, an impaired acute inflammatory response, and altered susceptibility to infection and faulty wound repair in patients with diabetes.

Adult↗
PubMed1986

Quantitative determination of antiviral nucleoside analog in DNA.

A technique for the analysis of the amount of an antiviral nucleoside analog incorporated into DNA, utilizing enzymatic digestion of DNA, followed by high-performance liquid chromatography is described. The cells or tissue samples were treated with perchloric acid to inactivate the nucleases, then digested with pronase in the presence of EDTA. DNA was purified by CsCl centrifugation followed by Sephadex chromatography and treatment with deoxyribonuclease 1 and venom phosphodiesterase. The deoxyribonucleoside monophosphates and the monophosphate of the nucleoside analog liberated from DNA were separated and quantitated by HPLC analysis and measurement of radioactivity. This assay is more sensitive, specific, and precise than the determination of DNA density shift. It is also applicable for nucleoside analogs which do not change the density of DNA either because of their structure or their very small degree of incorporation.

Animals↗
PubMed1986

"How to avoid dying from cancer ... now and later"--a course to reach the lay public.

The context, history, course description, measures and foundations for success, and future enhancements are described for the Health Education course, "How to Avoid Dying from Cancer ... Now and Later." Since 1981 this course has been offered once annually at The Ohio State University for academic credit and has averaged an enrollment of 354 undergraduate, graduate, and continuing education students. Over the years this course, originated by a surgical oncologist, has earned its own title and entry in the academic course offerings and has demonstrated success both quantitatively and qualitatively. Quantitative indicators of success include enrollment trends, diversities of students enrolled, student evaluations of the course, and data on the instructional effectiveness of this course. Qualitative indicators of success include favorable publicity through the local media, top ratings for summer radio programs based on this course, and the National University Continuing Education Faculty Service Award given to one of the authors in 1985. Four factors account for much of the success of this course.

Female↗
PubMed1985

Methods taught in dental schools for determining the posterior palatal seal region.

The following conclusions summarize the results of a survey sent to the chairperson of the removable prosthodontic department of 70 dental schools regarding the concepts and techniques taught for developing the posterior palatal seal. A combination of clinical methods was most frequently taught for locating the vibrating line. The phonation of the Ah sound was the most popular single method taught for locating the vibrating line. Seventy-five percent of the dental schools taught that there is one vibrating line per person. The posterior flexion line was related to the distal termination of the maxillary denture by dental schools that teach the concept of two vibrating lines. Most dental schools (80.4%) do not use the fovea palatinae for locating the distal termination of the maxillary denture. Most dental schools (87.5%) teach students to carve the posterior palatal seal on the maxillary master cast. Most dental schools (93.9%) take the compressibility of the palatal tissue into consideration when carving the depth of the posterior palatal seal in the maxillary master cast. The butterfly pattern was most frequently described to carve the posterior palatal seal in the maxillary master cast.

Dental Impression Technique↗
PubMed1985

Sociocultural correlates of childhood sporting activities: their implications for heart health.

The relative contribution of sex, ethnicity, social class, parental exercise and heart health knowledge to the variability of sporting activities reported by Texas 7th and 8th grade students in 1980 was examined to study the cultural patterns of exercise that might relate to future risk for heart disease. Girls were more likely than boys to participate in activities with high aerobic potential. Relative to Mexican-Americans and Blacks, Anglos were more likely to engage in individual, non-competitive, aerobic-type activities. Multivariate analysis showed heart knowledge, parental exercise, sex, father's occupation and ethnicity to be significantly related to the overall frequency of exercise. Parental exercise had a stronger influence on the frequency of exercise among girls than boys. These findings suggest possible cultural mechanisms in the epidemiology of heart disease.

Adolescent↗
PubMed1985

Criteria for the administration of KI for thyroid blocking of radioiodine.

Scientific data are reviewed to evaluate the risks of radioiodine uptake and to compare those risks with the benefits and risks of low milligram doses of stable potassium iodide (KI). The limit of 25 rad to the thyroid due to radioiodine uptake is adopted as the "break-even" point above which 130-mg KI doses should be administered. The biological and radiological kinetics of radioiodine for protracted uptakes were derived from the Medical Internal Radiation Dose Committee (MIRD) model (MIRD75). Resulting calculations yielded estimates of dose commitment rates to the thyroid as a function of thyroidal uptake. The extrapolated value of the 1-hr inhalation curve for 131I with 30% uptake compares well with the established MPCa value and intercepts the origin. The calculated KI-blocking efficiency as a function of time after radioiodine uptake agrees well with previously reported experimental data. The prevention or "blocking" of 25 rad to the thyroid was the criterion used to define critical values of radioiodine in the thyroid. Critical values are functions of isotope, the duration of uptake and the elapsed time between inhalation and assay of thyroid content. The presence of radioiodine in the thyroid in amounts greater than the critical value indicates that more than 25 rad to the thyroid can be averted, and KI should be administered in the absence of contraindications. Critical average concentrations are implicitly defined by the method of calculation used in the derivation. Critical average concentrations are presented as criteria for KI administration when assays of the radioiodine content of the thyroid are unavailable. Illustrative applications of critical values and critical average concentrations are presented in the Appendix.

Accidents↗
PubMed1985

Drug resistance patterns of herpes simplex virus isolates from patients treated with acyclovir.

A decrease in the in vitro sensitivity to acyclovir (ACV) was observed in successive isolates of herpes simplex virus type 1 from three immunocompromised patients during intravenous therapy with this drug. The ACV-resistant isolate from patient 1 was cross-resistant to dihydroxypropoxymethylguanine and bromovinyldeoxyuridine, but still susceptible to three fluoro-substituted pyrimidines, 2'-fluoro-5-iodo-1-beta-D-arabinofuranosylcytosine (FIAC), 2'-fluoro-5-iodo-1-beta-D-arabinofuranosyluracil (FIAU), and 2'-fluoro-5-iodo-1-beta-D-arabinofuranosylthymine (FMAU). The thymidine kinase (TK) from the resistant isolate showed a 50-fold or greater reduction in affinity for thymidine, FIAU, FMAU, and ACV, but the total enzyme activity was similar to that of the sensitive isolate. The ACV-resistant isolate from patient 2 was also resistant to dihydroxypropoxymethylguanine, bromovinyldeoxyuridine, and the fluoro-substituted compounds; TK activity for this isolate was less than 1% of the patient's pretherapy isolate. An isolate obtained during a subsequent recurrence in patient 2 was susceptible to ACV and the other TK-dependent agents. The ACV-resistant isolate from patient 3 was partially resistant to FIAC and FIAU but still susceptible to FMAU; the viral TK had a 10-fold-lower affinity for ACV, FIAU, and FMAU than did the sensitive pretherapy isolate, while the level of TK activity detected was reduced to 6%. In none of the isolates studied was a change in sensitivity to phosphonoformic acid observed. Compared with the corresponding pretherapy ACV-sensitive isolates, there was a 30-fold decrease in neurovirulence for mice of the two drug-resistant isolates with diminished levels of thymidine-phosphorylating activity and no change in virulence for the third isolate. These findings indicate that mixed patterns of drug-resistance to TK-dependent antiviral compounds can occur in clinical isolates, resulting from changes in either the amount or the affinity of viral TK activity.

Acyclovir↗