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Biomedical subjects

G Marks

Publications and source records attributed to G Marks.

At least 73 records · Page 4Linked to original sources
PubMed1992

Language acculturation and screening practices of elderly Hispanic women. The role of exposure to health-related information from the media.

The present study examined the hypothesis that language acculturation of Hispanics in the United States increases their exposure to media-based health information which, in turn, increases medical screening practices and knowledge of cancer symptoms. We interviewed 598 elderly Hispanic women (55-92 years of age) residing in Los Angeles. Language acculturation was measured with items on understanding of English and language preference for interpersonal communication, reading materials, television, and radio. Recency of screening (physician breast exam, Pap smear, routine physical exam, mammogram) and exposure to media-based health information were assessed with Likert-type scales; knowledge of symptoms of breast, cervical, colorectal, and oral cancers was assessed through open-ended questions. The results of multiple regression analyses provide support for the hypothesis. First, language acculturation predicted media exposure after controlling for demographic variables. Second, media exposure predicted screening and symptom knowledge after controlling for language acculturation and the demographic factors. The findings suggest that cancer prevention programs should use Spanish-language media to reach a wider Hispanic audience, especially those who are monolingual.

Acculturation↗
PubMed1991

High-dose preoperative radiation and radical sphincter-preserving surgery for rectal cancer.

To reduce local recurrence associated with rectal cancer and to extend the scope of anal sphincter preservation, a selective program of high-dose preoperative radiation therapy and sphincter-preserving surgery was initiated in 1976. High-energy photon therapy (40 to 60 Gy) was administered in doses of 1.8 to 2.5 Gy during a period of 4 1/2 to 6 weeks and followed in 4 to 6 weeks with curative sphincter-preserving surgery for clinicopathologically unfavorable and low rectal cancers. None of the 143 patients in the study died during the postoperative period. Fifteen (13%) of 117 patients followed up for at least 24 months experienced local recurrence. Acceptable sphincter function was retained in 130 patients (91%). Our program of high-dose preoperative radiation therapy and sphincter-preserving surgery for the treatment of high-risk cancers, including those in the distal third of the rectum, resulted in better-than-expected survival and control of local recurrence with acceptable morbidity and no mortality.

Combined Modality Therapy↗
PubMed1991

High dose preoperative irradiation for cancer of the rectum, 1976-1988.

Two hundred twenty patients with adenocarcinoma of the rectum have been treated in a program using high dose (greater than 4000 cGy) preoperative irradiation followed by radical surgical resection. The patients were staged on the basis of pretreatment clinical mobility of the cancers. Seventy-four patients had mobile cancers, 49 had partial fixation (tethered), 85 patients had total tumor fixation, and 12 patients had a frozen pelvis (unresectable). Patients were treated with high energy photons using a four field box technique with total doses ranging from 4000 to 6000 cGy. The overall incidence of local recurrence was 15% (32/220). Patients with fixed and unresectable tumors had a higher incidence of local recurrence, 20% (21/97) as compared with patients with mobile and partially fixed tumors, 10% (13/123). Local recurrence by pathological stage of disease was 6% for patients with Stages O, A, B1 versus 20% for patients with Stages B2 and C cancer. Overall 5-year survival of the total group was 67%. The 5-year survival by clinical stages of disease was 87% for mobile tumors, 74% for partially fixed tumors, 70% for fixed tumors, and 22% for the unresectable group. The 5-year survival by pathological stages of disease was 90% for those with Stage O, A, B1 and 71, 75, and 47%, respectively, for Stages B2, C1, and C2 disease.

Adenocarcinoma↗
PubMed1991

Preoperative irradiation for cancer of the rectum with extrarectal fixation.

Tumor mobility of rectal cancer is well known to have prognostic significance for operative resection, local recurrence, and survival. Between 1976-1988, 220 patients have been consecutively treated with high dose preoperative radiotherapy at Thomas Jefferson University Hospital. During this time period, 134 patients were clinically determined by the surgeon and radiotherapist to have extrarectal tumor fixation as a primary indication for preoperative irradiation and are the subject of this review. The patient population can be further divided into two subgroups which include 49 patients with clinical tethering/partial fixation, and 85 patients with completely fixed tumors. Patients were treated with 4-field pelvic radiotherapy to 45 Gy in 25 fractions. Depending on location and degree of fixation, a localized boost dose was frequently delivered to the tumor for an additional 4.8-9.6 Gy using opposed high-energy lateral fields. Surgical resection was instituted 4-6 weeks post completion of radiotherapy. Significant tumor regression permitted sphincter preserving surgery in 105/134 (78%) of these patients. With a median follow-up of 37 months, the overall 5-year actuarial survival for our postradiation Stage A/B1 patients was 92% (n = 28), and 63% for Stage B2/C patients (n = 91). Local recurrence occurred in only 7% of the Stage A/B1 patients, and 18% in the Stage B2/C patients. Analyzed by pre-treatment clinical evaluation, the 5-year actuarial survival of these patients was 68% and 60% in the clinically tethered and fixed tumor subgroups, respectively (p = .51). Pelvic control was demonstrated in 86% of the patients in the tethered subgroup, and in 80% of the preoperative fixed patients. The combined treatment was well tolerated, with complications limited to 6% of the patient population. We conclude that preoperative radiotherapy for rectal carcinomas with clinical extrarectal fixation provides optimal presurgical cytoreduction and excellent survival. Furthermore, sphincter function can be maintained in a majority of patients with appropriate attention to patient selection.

Adult↗
PubMed1991

Social influence processes affecting adolescent substance use.

Social influence is central to models of adolescent substance use. Nonetheless, researchers fail to delineate the various forms of social influence. A framework that distinguishes between active (explicit drug offers) and passive (social modeling and overestimation of friends' use) social pressure was tested. The effect of these processes on alcohol and cigarette use was examined with 526 seventh graders taking part in an alcohol prevention program. Hierarchical regression analyses demonstrated that pretest measures of alcohol use, offers, modeling, and overestimation each accounted for unique variance in posttest alcohol use. Similar results were obtained for cigarette smoking. The general model was not significantly different for boys and girls, or for prior users and prior nonusers, supporting the generalizability of the framework. Implications for intervention programs are discussed.

Adolescent↗
PubMed1991

Self-disclosure of HIV infection to sexual partners.

Self-disclosure of HIV infection to current sexual partners was examined in 138 seropositive men, mostly lower income Hispanics, from Los Angeles. Forty-five percent had been sexually active since learning their serostatus. Of these, 52% had kept their infection secret from one or more partners. The likelihood of disclosure decreased in direct proportion to the number of partners. Nondisclosure occurred in conjunction with unprotected receptive and insertive anal intercourse. Potential factors promoting nondisclosure are discussed.

HIV Seropositivity↗
PubMed1991

Quantitative immunocytochemical staining for recombinant tissue-type plasminogen activator in transfected Chinese hamster ovary cells.

Tissue-type plasminogen activator (tPA) is a serine protease which cleaves plasminogen to its active form, plasmin. tPA plays a physiologic role in hemostasis, wound healing, and embryogenesis. Therapeutically, recombinant human tPA is used as a thrombolytic in myocardial infarction. Although production of therapeutic quantities of tPA in Chinese hamster ovary (CHO) cells transfected with the human gene for tPA is practical, production costs remain high. One important factor which determines the ultimate cost of tPA (or any other recombinant protein expressed in mammalian cells) is its production level on a per cell basis. We have used postembedding immunocytochemical staining with colloidal gold to study the subcellular localization of tPA in CHO cells expressing recombinant tPA (rCHO) in an effort to understand the factor(s) which might limit secretion. Staining for tPA was evaluated visually and by morphometric analysis and was specific and reproducible. Serially passaged rCHO showed no significant change in staining density over 31 serial passages. Staining density was greatest over dilated cisternae of the rough endoplasmic reticulum and nuclear envelope. Golgi stacks and large acid phosphatase-positive vacuoles (probably lysosomes) were also heavily stained. Staining of lysosomal vacuoles suggested that rCHO might be degrading nascent tPA. Incubation of rCHO with 125I-tPA showed that the cells were not internalizing tPA from the media. These results suggest that rCHO fail to secrete a portion of the tPA they synthesize and that it is degraded in lysosomes. This observation may have important implications on the choice of expression systems for efficient production of large quantities of recombinant proteins.

Animals↗
PubMed1990

High-dose preoperative radiation and full-thickness local excision. A new option for patients with select cancers of the rectum.

Faced with the responsibility of treating patients with invasive distal rectal cancer who were medically unacceptable for the indicated radical surgery, a prospective study was initiated in which high dose preoperative radiation and full-thickness local excision were used. High dose preoperative radiation permitted full-thickness local excision of select cancers, which, by conventional standards, otherwise would have required radical surgery and permanent colostomy. Feasibility was measured on the basis of safety of the technique, control of the cancer, and the quality of anal sphincter function expected. Patients were selected initially because of their predicted inability to tolerate radical surgery, but indications were broadened to include those whose tumors had completely disappeared after irradiation. From 1984 to 1988, 20 patients underwent 21 operative procedures for cancers located between 0 and 7 cm from the anorectal ring. This report is concerned with the 14 patients of this group who were observed for a minimum of 24 months. High-dose preoperative radiation was administered for a total dose of 4500 cGy. Excision and repair were performed 4 to 6 weeks after completion of radiation therapy. Full-thickness disc or hemicircumferential excision was accomplished by transanal, transsphincteric, and transsacral techniques, which included, in several instances, excision of the sphincter mechanism and perineal body, and/or the vaginal wall. Full-thickness local excision after high-dose radiation therapy for rectal cancers has never been reported. Follow-up observation ranged from 24 to 48 months with a median of 31 months. Rectal reservoir function and sphincter control were good in 13 patients. Local recurrence developed in three patients (21 percent), two of whom had postradiation therapy B2 mucinous cancers. Three-year actuarial rate of local recurrence is 23 percent. One (7 percent) patient died of recurrent disease. Actuarial Kaplan-Meier survival at 3 years is 61 percent. Based on the results of this small, select patient group, high-dose radiation therapy followed by full-thickness local excision appears to be a reasonable option for patients who cannot tolerate radical surgery. This bimodal approach also may serve as an option for those who are good medical risks, but for whom sphincter preservation is at stake, and to whom radical surgery offers limited benefits.

Actuarial Analysis↗
PubMed1990

Phenotypic properties of herpesvirus-transformed cells with high tumorigenic and metastatic ability.

Herpes simplex virus type 2-transformed hamster embryo fibroblasts (333-8-9 cells) produce increased plasminogen activator (PA) compared with normal hamster cells. These cells produce undifferentiated fibrosarcomas at the inoculation site in newborn hamsters, and metastasize to the lungs. Using a direct PA assay, in which 125I-labeled plasminogen is cleaved, the optimum pH and osmolarity for detection of the 333-8-9 extracellular PA were pH 8.9 and approximately 150 mOsmol. Secretion of enzyme did not vary significantly on a per cell basis over cell densities from 0.1 to 8.0 X 10(7) cells/T-75 cm2 flask. This assay demonstrates that the 333-8-9 cells produce at least 20-fold greater levels of PA than normal cell counterparts. Based on the molecular weight (50-58 kDa) of secreted 333-8-9 cells PA and lack of fibrin stimulation, we conclude that it is a urokinase type PA. Subclonal lines of the 333-8-9 cells, selected for an increased PA phenotype were stable in culture, more tumorigenic and probably more metastatic. Correlation of these two events was examined by passaging 333-8-9 cells in vivo to select for greater tumorigenic potential and then determining the production of PA by the in vivo-derived sublines. The metastatic potential of the resulting cells was heterogeneous. Increased PA production upon increased passage in vivo did not always occur, whether the cells were passaged as subcutaneous tumors or as ascites tumors. Thus, while enzyme production correlated with tumorigenicity when selecting cells for an increased protease phenotype, this correlation was not observed when selecting for in vivo tumorigenicity. The results suggest that increased ability to make PA represents only one of multiple selective advantages for tumor growth.

Animals↗
PubMed1990

Adverse effects of acculturation: psychological distress among Mexican American young adults.

We examined the relationship between acculturation and psychological distress in young (20-30), middle aged (31-50), and older adult (51-74) Mexican Americans (n = 3084). The data were from the Hispanic Health and Nutrition Examination Survey (HHANES). Acculturation was measured with items on spoken and written language and ethnic identification. Psychological distress was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). We found that as acculturation increased, distress significantly increased in young adults but tended to decrease in older adults. This general pattern held for males and females and was consistent for the CES-D total score and caseness rates. The effects of acculturation were independent of the effects of income and education. We discuss that alienation and discrimination may be two intervening events producing the psychological distress of the highly acculturated young adults. Further, our findings tentatively suggest a longitudinal process whereby acculturated younger Mexican Americans attempting to advance themselves economically and socially in the dominant society strip themselves of traditional resources and ethnically-based social support. Through the years, however, they may re-establish ties to their native culture which contributes to relatively positive mental health.

Acculturation↗
PubMed1990

Acculturation, access to care, and use of preventive services by Hispanics: findings from HHANES 1982-84.

Use of preventive health services (physical, dental, and eye examinations, Pap smear and breast examinations) among Mexican American, Cuban American, and Puerto Rican adults (ages 20-74) was investigated with data from the HHANES. Analyses focused on the relative importance of two predictors of recency of screening: access to services (health insurance coverage, having a routine place for care, type of facility used, having a regular provider, travel time) and acculturation (spoken and written language, ethnic identification). Regression analyses controlling for age, education, and income indicated that utilization of the preventive services was predicted more strongly by access to care than by acculturation. For each Hispanic group, having a routine place for health care, health insurance coverage, and a regular provider were each significantly associated with greater recency of screening. Type of facility used and travel time produced less consistent effects. These results replicate past studies that have demonstrated the important link between institutional access and use of health services. Of the acculturation variables, language but not ethnic identification (which was measured only for the Mexican Americans) predicted use. This latter finding, which has been demonstrated in other studies as well, suggests that the effect of language on screening practices should not be interpreted as a cultural factor, but as an access factor, i.e. use of English favors access to services.

Acculturation↗
PubMed1990

Health risk behaviors of Hispanics in the United States: findings from HHANES, 1982-84.

With data from the Hispanic Health and Nutrition Examination Survey (HHANES), we examined several health risk behaviors (cigarette smoking, alcohol use, dietary practices, and recency of health screening) of Mexican American, Cuban American, and Puerto Rican adults (ages 20-74). For each sample, a greater percentage of men than women smoked cigarettes and used alcohol. Heavy smoking (20+ cigarettes per day) was most prevalent for Cuban American males, and heavy drinking (1.00+ oz ethanol per day) was most prevalent for Mexican American and Puerto Rican men. Acculturation correlated positively with alcohol use (particularly for females) and negatively with dietary balance (for Mexican American men and women). The Puerto Ricans' diet was less balanced than that of the other two groups. For each sample, more men than women had not had a routine physical or dental examination within the past five years; the recency of screening was lowest for Mexican American men. Screening (including Pap smear for the women) was lower for those who smoked cigarettes and for those with poor dietary practices, indicating that many Hispanics at special risk of disease underutilize preventive health services, increasing the likelihood of diagnosis at a later stage of illness.

Acculturation↗
PubMed1990

Physical features, physical attractiveness, and psychological adjustment among alcohol abuse inpatients.

Relations between specific physical features, attractiveness, and psychological adjustment of alcoholic inpatients were examined. Measures were obtained during the first week of admission and 6 weeks later (within 2 weeks of discharge). The nine physical features assessed formed three factors: face, facial expression, and body. The face factor was more strongly related to history of substance abuse than was either of the other factors. Further, the results suggested that alcoholism-related face features may be responsible for the documented relation between ratings of overall physical attractiveness and ratings of adjustment obtained at admission to a chemical dependency program; however, positive changes in body features less specifically related to a history of substance abuse (posture and grooming) are associated with counselors' ratings of improved patient adjustment over time.

Adaptation, Psychological↗
PubMed1989

Depressive symptomatology among Mexican-American adults: an examination with the CES-D Scale.

The presence and persistence of specific depressive symptomatology among a large sample of Mexican-American adults (n = 3,084) were examined with the Center for Epidemiologic Studies Depression (CES-D) Scale. Compared to studies of Anglos, a substantially larger percentage reported persistent hopelessness about the future (29%), self-depreciation (21%), and lack of enjoyment out of life (14%). The prevalence of these symptoms was higher among those who had not adapted to mainstream American society and among older participants. Women were generally more distressed than men. Factor analyses of the items demonstrated a slightly different factor structure than previously obtained with Anglos. For both sexes and for those under age 30 and ages 30-59, the items "loneliness," "sadness," and "crying" loaded on a common factor. The tendency for these items to group together was stronger for those exhibiting a low or medium degree of cultural adaptation than for those exhibiting a high degree of adaptation. Discussion focuses on the cultural variation of response to items on the CES-D.

Acculturation↗
PubMed1989

The surgeon as endoscopist.

Because extraordinary benefits accrue to the patient when the surgeon can view the site of disease first-hand, the gastrointestinal surgeon must be a proficient endoscopist, and endoscopy must be part of gastrointestinal surgery. Leaders of surgical organizations and surgeon educators, upon whom rests the responsibility for shaping policy and educating medical students and residents, should remain alert to the need to maintain a substantial surgical presence in gastrointestinal endoscopy.

Digestive System↗
PubMed1989

Staging of rectal carcinoma: prospective comparison of endorectal US and CT.

One hundred two consecutive patients undergoing surgical treatment for rectal cancer were examined by means of endorectal ultrasound (US) for staging before surgery. Eighty-one of these patients also underwent staging with computed tomography (CT). The diagnostic sensitivity of endorectal US in detection of tumor extension into fat was 67%; specificity, 77%; positive predictive value, 73%; and negative predictive value, 72%. The sensitivity of CT for this finding was 53%; specificity, 53%; positive predictive value, 56%; and negative predictive value, 50%. The sensitivity of endorectal US in detection of lymph node infiltration was 50%; specificity, 92%; positive predictive value, 68%; and negative predictive value, 84%. For this finding the sensitivity and negative predictive value, 76%. These findings suggest that endorectal US may be as accurate as CT, or more so, in the preoperative staging of rectal cancer.

Adipose Tissue↗