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Biomedical subjects

B H Dorman

Publications and source records attributed to B H Dorman.

50 records · Page 3Linked to original sources

Use of a combined right ventricular ejection fraction-oximetry catheter system for coronary bypass surgery.

OBJECTIVE: To evaluate the reproducibility and accuracy of a new pulmonary artery catheter system that provides both right ventricular ejection fraction and continuous venous oxygen saturation monitoring. DESIGN: Criterion standard study. SETTING: University medical center. PATIENTS: A consecutive sample of ten patients undergoing elective coronary artery bypass surgery provided informed consent for the study. Exclusion criteria included emergency surgery or clinically important preoperative tricuspid regurgitation as assessed by echocardiography. None of the patient sample was excluded. MEASUREMENTS: Catheter-derived mixed venous and arterial oximetry data were compared with simultaneous values obtained using conventional laboratory cooximetry methods. Measurements were performed before cardiopulmonary bypass and intermittently up to 48 hrs after cardiopulmonary bypass. The variability of cardiac output and computed right ventricular ejection fraction was also assessed concurrently with the oximetry analysis. RESULTS: A significant correlation was observed for mixed venous oxygen saturation between catheter-derived and laboratory cooximetry data (r2 = .81, p < .01). Similarly, arterial oxygen saturation values obtained from pulse oximetry and laboratory values were significantly related (r2 = .81, p < .01). The coefficient of variation for each set of five repeated measurements for cardiac output was 8%, and for computed right ventricular ejection fraction, it was 16%. CONCLUSIONS: The combined catheter system provides the means to monitor both mixed venous oxygen saturation and right ventricular ejection fraction. These data provide a reliable and detailed assessment of cardiopulmonary function that should prove beneficial in the critical care setting.

Aged↗

Prophylactic transdermal scopolamine patches reduce nausea in postoperative patients receiving epidural morphine.

To evaluate the efficacy of prophylactic transdermal scopolamine in reducing nausea associated with postoperative epidural analgesia, we studied 32 healthy adult women undergoing major gynecologic surgery. The patients were randomized in a double blind fashion to receive either a cutaneous scopolamine patch or a visually identical cutaneous placebo patch. Postoperative analgesia was provided solely with epidural morphine. Nausea was treated with metoclopramide and droperidol. At 24 hours postoperatively, the mean nausea score was significantly lower with scopolamine than with placebo (1 +/- 2 vs 51 +/- 42, respectively, P less than 0.05). The number of patients reporting "zero nausea" was significantly greater with scopolamine patches than with placebo patches (13 vs 1, P less than 0.01). The mean number of times antiemetic drugs were administered per patient was lower with scopolamine than with placebo patches (0.2 +/- 0.4 vs 2.8 +/- 2.6, P less than 0.05). It is concluded that prophylactic transdermal scopolamine patches reduce nausea in postoperative patients receiving epidural morphine.

Administration, Cutaneous↗

Effect of mouse skin tumor promoters upon [3H]uridine exchange and focus formation in cultures of C3H/10T1/2 mouse fibroblasts.

The abilities of 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate (4-O-methyl-TPA) and mezerein to promote the process of transformation were evaluated in cultures of C3H/10T1/2 mouse embryo fibroblasts treated with N-methyl-N'-nitro-N-nitrosoguanidine. Mezerein was found to be as potent as the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) for the promotion of focus formation, eliciting a promotion response at concentrations that ranged from 100 to 2500 ng/ml. 4-O-Methyl-TPA (25-2500 ng/ml) did not promote focus formation, but was mitogenic for confluent cultures. The effects of promoting and non-promoting compounds upon intercellular communication were then evaluated to determine if a rapid assay for the inhibition of communication might serve as a surrogate for the relatively long term, labor-intensive cell transformation assay. Inhibited intercellular communication, as measured by inhibition of [3H]uridine exchange between cells, appeared to correlate with the ability of phorbol related compounds to promote transformation. However, the potent promoter 2,3,7,8-tetrachlorodibenzo-p-dioxin did not inhibit [3H]uridine transfer. Inhibition of intercellular communication may thus be diagnostic of the promoting potential of phorbol-related compounds in C3H/10T1/2 cultures, but may not be an appropriate endpoint for the study of carcinogenic dioxins.

Animals↗

Limiting factors of the V79 cell metabolic cooperation assay for tumor promoters.

A number of chemicals which promote tumorigenesis in vivo have been observed to inhibit metabolic cooperation between 6-thioguanine-resistant (TGR) and sensitive (TGS) Chinese hamster lung V79 cells. The apparent correlation between an inhibition of metabolic cooperation in V79 cells in vitro and promotion of oncogenesis in vivo has led to the suggested utilization of the assay as a screen for tumor promoters. However, many features of the V79 metabolic cooperation assay which would provide for an improved understanding of the usefulness and limitations of the assay have not been well characterized. A number of experimental parameters involved in the metabolic cooperation assay were examined with 12-O-tetradecanoylphorbol-13-acetate (TPA). TPA inhibited metabolic cooperation between V79 cells in a dose-dependent manner, and thereby increased the recovery of TGR cells co-cultured with TGS cells in the presence of 6-thioguanine. Approximately 90% recovery of TGR cells was achieved at TPA concentrations of 1--1000 ng/ml, a 9- to 11-fold higher yield than the average background recovery of 8--10% in acetone-treated cultures. The TPA-induced inhibition of metabolic cooperation was observed to be transient. Pretreatment of TGS and TGR cells with TPA for 12 h or more prior to 6-thioguanine addition resulted in no inhibition of metabolic cooperation. It was further determined that the presence of TPA was required for only 1 h to maximally inhibit metabolic cooperation, a significantly reduced period of exposure relative to the originally proposed 4 day exposure. Technical grade dinitrotoluene (DNT), 2,4-DNT and 2,6-DNT which have demonstrated promoting activity in rat liver did not increase the recovery of TGR cells. However, the solvent dimethylsulfoxide (DMSO) at concentrations ranging from 1.0 to 2.5% increased the recovery of TGR cells in a dose-dependent manner. The short-lived effect of TPA suggests that inhibition of metabolic cooperation may not bear a mechanistic relationship to tumor promotion. The inhibition of metabolic cooperation by DMSO, the requirement for only short-lived reductions in metabolic cooperation for maximal TGR cell recovery, and the lack of inhibition by DNT suggests that caution should be exercised when interpreting the results of this bioassay.

Animals↗

Role of intercellular communication in the promotion of C3H/10T1/2 cell transformation.

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) upon intercellular communication and promotion were studied in cultures of C3H/10T1/2 mouse embryo fibroblasts. Cell-to-cell communication was quantitated by autoradiographic analysis of [3H]uridine transfer from prelabelled donor cells to an excess of unlabelled recipient cells during a 4 h co-cultivation. Extensive transfer of label was observed from donor to recipient cells in contact. Treatment of non-transformed C3H/10T1/2 cultures with 250 ng/ml TPA at co-cultivation of donor and recipient cells markedly inhibited intercellular communication during the 4 h incubation, producing an 80% reduction in uridine exchange relative to solvent-treated control cultures. Concentrations of TPA ranging from 0.25 to 25 ng/ml were also effective in inhibiting [3H]uridine exchange in a dose dependent fashion from 13% to 74%. This inhibition of intercellular communication was transient; cells exposed to 250 ng/ml TPA for 1.5 h prior to co-cultivation with TPA exhibited a 60% inhibition and the exchange of uridine had increased to control values in cultures pretreated for 12-72 h. An examination of label transfer between non-transformed and transformed C3H/10T1/2 cells indicated that both the extent of inhibition by TPA and the kinetics of communication inhibition were similar to that observed for non-transformed cells. Initiation and promotion experiments demonstrated that exposure to 250 ng/ml TPA for 5 weeks, but not to reduced concentrations of 0.25, 2.5 or 25 ng/ml, was capable of promoting morphological transformation. The lack of correlation between the dose responses of TPA for promotion and for reduction of cell-to-cell communication, and the transient nature of intercellular communication inhibition by TPA, suggests that an inhibition of cell-to-cell communication is not a sufficient event for promotion of oncogenic transformation in these cells.

Animals↗

Alterations of human endometrial stromal cells produced by N-methyl-N'-nitro-N-nitrosoguanidine.

Stromal cell cultures obtained from human endometrium were treated repetitively with N-methyl-N'-nitro-N-nitrosoguanidine in vitro at concentrations ranging from 0.5 to 4.0 micrograms/ml, and alterations in growth potential and morphology were analyzed. A single exposure to the carcinogen resulted in morphological evidence of toxicity and reductions in growth rates, plating efficiency, and saturation density as compared to solvent-treated control cells. Cytotoxicity was reduced after additional exposures to the carcinogen. Following repetitive treatments with N-methyl-N'-nitro-N-nitrosoguanidine, human endometrial stromal cells developed enhanced growth potential, the capacity to form macroscopic colonies in soft agar, and elevated gamma-glutamyltranspeptidase activity. Carcinogen-treated cells displayed atypical morphology characterized by irregularities in cell and nuclear size and shape, large bizarre nucleoli, increased nuclear:cytoplasmic ratios, and cellular crowding. Control cells did not display altered morphology or growth parameters even following multiple exposures to solvent and repetitive subculturing. These alterations in growth potential and morphology suggest that the cells are progressing towards preneoplastic and perhaps neoplastic transformation in vitro.

Agar↗

Monolayer culture of human endometrium: methods of culture and identification of cell types.

Monolayer cultures can be established from human endometrial tissue after enzymatic dispersal into isolated glands or single cells. Three cell types that have distinct morphology by light and electron microscopy are observed in the resulting primary cultures. One cell type, an elongated spindle cell, is similar in appearance to fibroblasts derived from other tissues. A second cell type forms colonies of tightly cohesive cells, ranging in shape from oval to polygonal. These cells have typical organelles and junctional complexes characteristic of epithelial cells from the endometrium. The third cell type assumes a pavement-like appearance composed of polygonal cells when viewed by phase contrast microscopy, but lacks distinctive ultrastructural features of epithelial cells. These cells in culture resemble the endometrial stromal cell, the predominant cell type of the human endometrium in vivo. The epithelial cell does not survive subculturing but the other two cell types can be passaged through several generations and can be stored in liquid nitrogen and subsequently returned to culture.

Cells, Cultured↗

Morphology and growth potential of stromal cell cultures derived from human endometrium.

Propagable cell cultures derived from human endometrial tissue were determined to contain cells predominantly of stromal cell origin based on their morphologic resemblance to endometrial stromal cells. These features included nexi, solitary cilia, and predecidual cytology. In addition to morphology the cell cultures retained a normal karyotype and responded to steroid hormones as evidenced by cellular aggregation. The stromal cells were evaluated for a variety of characteristics associated with transformed cells and seemed to be biologically normal without neoplastic phenotypes. Growth potential of the stromal cell cultures was also characterized in normal maintenance medium, in nutritionally depleted medium with reduced levels of calcium or serum, and in medium with increased levels of serum. The prolonged survival of the stromal cells in vitro coupled with the retention of in vivo characteristics and an absence of neoplastic phenotype provides a human cell system that is amenable to a variety of long-term experimental analyses.

Cell Aggregation↗

Benzo(a)pyrene binding to DNA in organ cultures of human endometrium.

Benzo(a)pyrene was found to bind to DNA in human endometrial tissue in vitro. Among specimens from 41 individuals examined, there was a 70-fold range in the observed specific activities of carcinogen binding to DNA. To determine whether this interindividual variability was correlated with the hormonally determined state of differentiation of the endometrial tissue, this population was subdivided to separate postmenopausal patients from premenopausal patients; among premenopausal patients, further division was made according to location within the menstrual cycle. Tissue obtained late in the proliferative phase or early in the secretory phase of the menstrual cycle had the highest mean specific activity of benzo(a)pyrene binding. In spite of the relatively small group sizes, the observed difference between this and the level of benzo(a)pyrene binding in the mid- and late secretory phases was statistically significant. The average binding level among the small number of patients studied who had entered a natural menopause was lower than the average binding for any of the subgroups of premenopausal patients and significantly lower than the mean for the whole population of premenopausal patients.

Adult↗

Complete brachial plexus palsy after total shoulder arthroplasty done with interscalene block anesthesia.

BACKGROUND AND OBJECTIVES: This report illustrates that brachial plexus palsy can result from either interscalene block or total shoulder arthroplasty. It is often impossible to determine which procedure caused the deficit; therefore, we believe the focus should be placed on treatment of the neurologic deficit. This report provides a suggested algorithm for diagnosis and treatment of postprocedure brachial plexus palsy. METHODS: Interscalene block was used as the operative anesthetic for our patient's total shoulder arthroplasty. Complete brachial plexus palsy was diagnosed postoperatively. RESULTS: The patient's postoperative treatment and recovery are described. CONCLUSIONS: Proper diagnosis and treatment of postprocedure brachial plexus palsy may improve recovery of function. Several precautions may reduce the likelihood of brachial plexus palsy following interscalene block for total shoulder arthroplasty.

Adult↗

Tranexamic acid reduces bleeding after cardiopulmonary bypass when compared to epsilon aminocaproic acid and placebo.

UNLABELLED: Perioperative bleeding following coronary artery bypass grafting (CABG) is associated with increased blood product usage. Although aprotonin is effective in reducing perioperative blood loss, excessive cost prohibits routine utilization. Epsilon aminocaproic acid (EACA) and tranexamic acid (TA) are inexpensive antifibrinolytic agents, which, when given prophylactically, may reduce blood loss. The present study was undertaken to compare the efficacy of TA and EACA in reducing perioperative blood loss. METHODS: The study population consisted of first-time CABG patients. Patients were allocated in a prospective double-blind fashion: (1) group EACA (loading dose 15 mg/kg, continuous infusion 10 mg/kg per hour for 6 hours, N = 20); (2) group TA (loading dose 15 mg/kg, continuous infusion 1 mg/kg per hour for 6 hours, N = 20); (3) control group (infusion of normal saline for 6 hours, N = 19). RESULTS: Treatment groups were similar preoperatively. No significant difference in intraoperative blood loss or perioperative use of blood products was noted. D-dimer concentration was elevated in the control group compared to the EACA and TA groups (p < 0.05). Group TA had less postoperative blood loss than the EACA and control groups at 6 and 12 hours postoperatively (p < 0.05). TA had reduced total blood loss (600 +/- 49 mL) postoperatively compared to EACA (961 +/- 148 mL) and control (1060 +/- 127 mL, p < 0.05). CONCLUSION: TA and EACA effectively inhibited fibrinolytic activity intraoperatively and throughout the first 24 hours postoperatively. TA was more effective in reducing blood loss postoperatively following CABG. This suggests that TA may be beneficial as an effective and inexpensive antifibrinolytic in first-time CABG patients.

Aminocaproic Acid↗