Biomedical subjects

J Seng

Publications and source records attributed to J Seng.

4 recordsLinked to original sources

PubMed2005

Experience with minimally invasive esophagectomy.

BACKGROUND: Minimally invasive esophagectomy (MIE) is an evolving surgical alternative to traditional open esophagectomy. Despite considerable technical challenges, it was hypothesized that MIE could be performed effectively by surgeons experienced in open esophageal resection and advanced laparoscopic surgery. The authors report their experience with 25 patients who underwent MIE for esophageal disease. METHODS: A multidisciplinary esophageal cancer team evaluated all the patients enrolled in this institutional review board-approved retrospective review study. Over an 18-month period, 25 consecutive patients (22 men and 3 women; mean age, 62 years; range, 48-77 years) with resectable esophageal cancer underwent MIE. Six patients were treated with neoadjuvant chemoradiotherapy. The preoperative diagnoses were adenocarcinoma (64%, n = 16), high-grade dysplasia (20%, n = 5), and squamous cell cancer (16%, n = 4). The outcomes evaluated included operative course, hospital and intensive care unit lengths of stay, pathologic stage, morbidity, and mortality. RESULTS: Two patients required conversion to open esophagectomy. Operative mortality was 4% (n = 1). The mean operative time was 350 min (range, 300-480), and the average blood loss was 200 ml. The patients remained ventilated for a median of 12 h, and the median intensive care unit utilization was 1 day. The median hospital length of stay was 9 days (range, 6-33 days). Major complications occurred in 32% of the patients. The anastomotic leak rate was 12%. Minor pulmonary complications occurred in 32% and atrial fibrillation in 16% of the patients. An anastomotic stricture developed in 24% of all the patients. One patient showed a positive proximal margin in the final pathology results. CONCLUSIONS: Minimally invasive esophagectomy is a technically challenging procedure that can be performed safely at the Virginia Piper Cancer Institute. Optimal results require appropriate patient selection and a multidisciplinary team experienced in the management of esophageal cancer.

Adenocarcinoma↗

PubMed1999

Adaptive role of caloric intake on the degenerative disease processes.

Carcinogenicity and aging are characterized by a set of complex endpoints, which appear as a series of molecular events. Many of these events can be modified by caloric intake. Since most of these processes determine an organism's ability to cope with various environmental stressors, it is not surprising that a relationship (in the presence of a constant nutrient density) exists between caloric intake and time-to-tumor and/or life span. Our studies have clearly shown that generally, the greater the caloric intake, the greater the body weight, the higher the incidence of spontaneous tumor occurrence, the greater the susceptibility to chemical carcinogens, and the shorter the life span. It is also recognized that variables other than body weight influence the life span and carcinogenesis. We have focused our attention on the questions of how and to what extent caloric intake modifies those homeostatic processes believed to be critical in determining the ability of an organism to cope with endogenous and exogenous stresses such as chemical, physical, and biological carcinogens. The response of an organism to its environment can be divided into four categories--physiological, metabolic, molecular, and cellular. We have found that, from a physiological perspective, decreasing caloric intake causes body temperature in rodents to be decreased by 0.5 to 1.8 degrees C and water consumption to be increased by 80%, as is running activity. However, metabolic output per gram of lean body mass is not altered. Reproductive capacity declines, whereas the ECG waveform is preserved as caloric intake decreases. Alterations in these and other physiological functions suggests that energy intake serves as a signal to up-regulate or down-regulate functions related to the flight-or-fight response observed in placental mammals. A number of key metabolic pathways are altered as a function of lowered caloric intake, even though the rate of food consumption per gram of lean body mass remains steady during body weight decreases caused by decreasing caloric intake. Pharmacological compartmentalization, however, is altered. As caloric intake declines, changes occur in the expression of a number of drug-metabolizing enzymes, with the most striking effect seen in sex-specific growth hormones and liver-dependent phase I and phase II enzymes. Additionally, oxidative stress (free-radical and mediated damage to macromolecules) appears to decrease as a function of reduced caloric intake. A number of molecular processes also change with changes in energy consumption. Our studies have shown that, regardless of the source and nature of DNA damage, DNA repair is better preserved and/or enhanced when caloric consumption decreases. In addition, the fidelity of DNA replication increases and oncogene expression is stabilized, P53 gene expression is increased, and apoptosis is elevated by up to 500% with decreased caloric intake. At the cellular level, cell proliferation is decreased in direct proportion to lower energy intake in some but not all tissues. Studies have also shown an enhancement in immune capacity, changes in IGF1, and accelerated rates of wound healing proportionate to declines in energy consumption. Our most recent findings, however, have shown that the benefits associated with decreases in caloric intake only occur in the presence of sufficient nutrient quality and density. In the absence of proper nutrition, however, sensitivity to carcinogens and toxic substances appears to be enhanced. These findings are supported by independent studies. These observations have led us to conclude that, in certain organisms, when caloric intake is decreased, there is an up-regulation of those processes that modulate the responses to a wide range of environmental stressors. This response allows for a better survival rate and a down-regulation of reproductive activity. It is our belief that, during periods of environmental stress, these systems may be essential to perpetu

Adaptation, Physiological↗

PubMed1996

The use of transgenic cell lines for evaluating toxic metabolites of carbamazepine.

Human lymphoblastoid cell lines transgenic for human CYP450s were evaluated for the identification of toxic metabolites of the anticonvulsant drug carbamazepine (CBZ). Human CYP450 isoforms expressed by these cell lines included 1A1, 1A2, 2E1, 2A6, and 3A4. A dose-dependent inhibition of population growth from 50-200 micrograms/ml CBZ was detected by measuring cell number and respiration. The inhibition increased with the growth rate of the various lines, which correlated inversely with the presence of CYP450s, and may have been caused by CBZ itself. Cytotoxicity was observed only at the highest dose and in the line lacking transfected CYP450s. Microsomal preparations from hCYP3A4/OR cells converted CBZ into its principal oxidative metabolite, carbamazepine-10,11-epoxide (CBZ-E), at a rate of 630 pmol/min per mg protein, confirming a major role of CYP3A4 in this reaction. However, no CBZ-E (or any metabolite) was recovered from any whole-cell incubation even though hCYP3A4 cells readily converted testosterone to 6 beta-hydroxytestosterone. This suggests that differences exist between whole-cell and microsomal preparations of lymphoblastoid cells in their ability to metabolize CBZ.

Aryl Hydrocarbon Hydroxylases↗

PubMedDate not supplied

Physical activity and postpartum well-being.

OBJECTIVE: To describe reported patterns of postpartum physical activity and to identify benefits or risks associated with postpartum physical activity at 6 weeks postpartum. DESIGN: Secondary analysis of longitudinal data collected prenatally and postpartum in a study of obstetric outcomes at a midwestern tertiary-care center and its ambulatory satellite and hospital clinics. PARTICIPANTS: One thousand three women completed a questionnaire at the 6-week postpartum clinic visit. Mean age was 29.7 years, and mean education level was 15.3 years. VARIABLES OF INTEREST: Participation in vigorous exercise, change in postpartum activity level, postpartum weight retention, infant feeding method, maternal postpartum adaptation, and participation in activities for fun. RESULTS: Nearly 35% reported doing vigorous exercise with a modal frequency of three times per week. More active women had retained significantly less weight (8.6 lb [3.9 kg]) than their less active counterparts (11.3 lb [5.1 kg]). Vigorous exercisers demonstrated a consistent pattern of better scores on measures of postpartum adaptation and were more likely than nonexercisers to participate in fun activities, such as socializing, hobbies, and entertainment. Breastfeeding was not adversely affected by vigorous exercise. CONCLUSIONS: These exploratory results indicate that physical and psychologic benefits may accrue to postpartum women who are able to exercise vigorously and avoid decreasing their usual level of activity. A prospective randomized test of this relationship is warranted. Although positive outcomes of physical activity have been demonstrated in the population at large, exercise has rarely been an element in postpartum care plans. Nurses who care for women after childbirth should assess women's exercise goals and support them in their desired activities.

Adaptation, Psychological↗