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Biomedical subjects

I Greenberg

Publications and source records attributed to I Greenberg.

At least 19 recordsLinked to original sources
PubMed2003

Complications of tracheal and thoracic surgery: the role of multisection helical CT and computerized reformations.

Helical computed tomography (CT) has an important role in the evaluation of a wide range of congenital and acquired thoracic abnormalities. The development of advanced computerized reformations enables the generation of bronchographic and bronchoscopic images of the tracheobronchial tree, as well as angiographic images of pulmonary arteries and veins. Additionally, it provides coronal and sagittal reconstruction imaging of parenchymal abnormalities. This information is obtained by a 20-30s procedure on a typical single channel system, which makes helical CT an optimal technique for the evaluation of patients undergoing major upper airways and thoracic interventions. The recent introduction of multisection CT scanners allows faster imaging of patients with thinner collimation, thus improving spatial resolution along the longitudinal (z) axis of the patient along with reduction of motion artefacts. This article demonstrates the use of dual and quad-section helical CT in the postoperative evaluation of patients undergoing laryngo-tracheal and thoracic interventions, including laryngoplasty, tracheal endoscopic laser ablation, lobectomy, pneumonectomy, lung transplantation, sleeve resection, pulmonary angioplasty, and pulmonary artery thromboendarterectomy. Emphasis is given to the additive value of using computerized reformations over axial images, especially for delineation of complex postoperative anatomical details in the tracheobronchial tree and pulmonary vasculature.

Adolescent↗
PubMed2001

High-performance liquid chromatography/mass spectrometry characterization of Ki4B-Ras in PSN-1 cells treated with the prenyltransferase inhibitor L-778,123.

Cellular transformation by Ras oncoproteins requires the posttranslation modification of farnesylation in a reaction catalyzed by farnesyl protein transferase (FPTase). Thus, inhibitors of FPTase have been developed as potential anticancer agents. However, recent studies with selective inhibitors of FPTase have shown that Ki4B-Ras retains its ability to transform cells by undergoing alternative prenylation by the related geranylgeranyl protein transferase I (GGPTase-I) in human tumor cells. We have developed a high-performance liquid chromatography/mass spectrometry assay for the detection and quantitation of the different processing states of Ki4B-Ras isolated from PSN-1 cells (a human pancreatic cell line with an activating Gly12 to Arg mutation) treated with the prenyltransferase inhibitor, L-778,123. Recently tested in the clinic, L-778,123 is a potent inhibitor of FPTase (in vitro IC50 = 2 nM) with some activity against GGPTase-I (in vitro IC50 = 98 nM). We find primarily farnesylated-Ki4B-Ras in vehicle-treated PSN-1 cells, a mixture of farnesylated- and geranylgeranylated-Ki4B-Ras in cells treated with nanomolar concentrations of L-778,123, and a mixture of unprocessed, farnesylated, and geranylgeranylated-Ki4B-Ras in cells treated with micromolar concentrations of compound. Of importance, this technique does not require metabolic labeling and may be used as a pharmacodynamic assay for Ki4B-Ras processing in mouse models.

Alkyl and Aryl Transferases↗
PubMed2001

Prevalence of the juxtaphrenic peak after upper lobectomy.

OBJECTIVE: The purpose of this study was to determine the prevalence of the juxtaphrenic peak after upper lobectomy in a large number of consecutive patients. MATERIALS AND METHODS: Available chest radiographs of 172 of 199 sequential patients who had undergone upper lobectomy in a university hospital were evaluated for the presence of a juxtaphrenic peak. The study included 98 cases with right upper lobectomy and 74 with left upper lobectomy. Radiographs were grouped in three postoperative periods: period I, within 7 days after lobectomy (n = 142); period II, between 8 and 30 days (n = 113); and period III, 31 days or more after lobectomy (n = 101). Four experienced radiologists in consensus determined the prevalence of the "juxtaphrenic peak sign," in relation to age, sex, side of lobectomy, positioning (erect or supine), presence of juxtadiaphragmatic abnormalities, and time interval since surgery. RESULTS: The prevalence of the juxtaphrenic peak sign gradually increased from 40.6% in period I to 71.9% in period III after right upper lobectomy (p < 0.01), and from 19% to 47.7%, respectively, after left upper lobectomy (p < 0.01). Its overall prevalence was significantly higher after right upper lobectomy (58.2%) than after left upper lobectomy (40.5%) (p = 0.02), and on erect chest films (51.4%) than on supine ones (28.9%). CONCLUSION: The prevalence of the juxtaphrenic peak sign increases gradually during the weeks following lobectomy. It is more frequent on erect films and after right upper lobectomy. The juxtaphrenic peak may serve as an additional useful radiologic sign suggesting upper lobectomy.

Adolescent↗
PubMed2000

Mouse mammary tumor virus-Ki-rasB transgenic mice develop mammary carcinomas that can be growth-inhibited by a farnesyl:protein transferase inhibitor.

For Ras oncoproteins to transform mammalian cells, they must be posttranslationally modified with a farnesyl group in a reaction catalyzed by the enzyme farnesyl:protein transferase (FPTase). Inhibitors of FPTase have therefore been developed as potential anticancer agents. These compounds reverse many of the malignant phenotypes of Ras-transformed cells in culture and inhibit the growth of tumor xenografts in nude mice. Furthermore, the FPTase inhibitor (FTI) L-744,832 causes tumor regression in mouse mammary tumor virus (MMTV)-v-Ha-ras transgenic mice and tumor stasis in MMTV-N-ras mice. Although these data support the further development of FTIs, it should be noted that Ki-ras is the ras gene most frequently mutated in human cancers. Moreover, Ki-RasB binds more tightly to FPTase than either Ha- or N-Ras, and thus higher concentrations of FTIs that are competitive with the protein substrate may be required to inhibit Ki-Ras processing. Given the unique biochemical and biological features of Ki-RasB, it is important to evaluate the efficacy of FTIs or any other modulator of oncogenic Ras function in model systems expressing this Ras oncoprotein. We have developed strains of transgenic mice carrying the human Ki-rasB cDNA with an activating mutation (G12V) under the control of the MMTV enhancer/promoter. The predominant pathological feature that develops in these mice is the stochastic appearance of mammary adenocarcinomas. High levels of the Ki-rasB transgene RNA are detected in these tumors. Treatment of MMTV-Ki-rasB mice with L-744,832 caused inhibition of tumor growth in the absence of systemic toxicity. Although FPTase activity was inhibited in tumors from the treated mice, unprocessed Ki-RasB was not detected. These results demonstrate the utility of the MMTV-Ki-rasB transgenic mice for testing potential anticancer agents. Additionally, the data suggest that although the FTI L-744,832 can inhibit tumor growth in this model, Ki-Ras may not be the sole mediator of the biological effects of the FTI.

Alkyl and Aryl Transferases↗
PubMed1999

Plasma lipid changes after supplementation with beta-glucan fiber from yeast.

BACKGROUND: Dietary fiber has been shown to improve blood lipids. OBJECTIVE: The purpose of this study was to evaluate the effect on serum lipids of a yeast-derived beta-glucan fiber in 15 free-living, obese, hypercholesterolemic men. DESIGN: After a 3-wk period in which subjects ate their usual diet, 15 g fiber/d was added to the diet for 8 wk and then stopped for 4 wk. Plasma lipids were measured weekly during baseline and at week 7 and 8 of fiber consumption, and again at week 12. RESULTS: Compared with baseline, fiber consumption significantly reduced plasma total cholesterol (by 8% at week 7 and 6% at week 8; P < 0.05 using Bonferroni correction); week 12 values did not differ from baseline. No significant differences were noted between baseline LDL cholesterol and values at weeks 7, 8, or 12 when comparing individual groups by using Bonferroni correction, even though the overall one-way analysis of variance with repeated measures was highly significant (P < 0.001). LDL-cholesterol concentrations did decline by 8% at week 8 compared with baseline. There was a significant effect of diet on plasma HDL-cholesterol concentrations (P < 0.005 by one-way ANOVA with repeated measures). However, a group difference was observed only between baseline and week 12 (16% increase; P < 0.05 by Bonferroni correction). Triacylglycerol concentrations did not change. CONCLUSIONS: The yeast-derived beta-glucan fiber significantly lowered total cholesterol concentrations and was well tolerated; HDL-cholesterol concentrations rose, but only 4 wk after the fiber was stopped.

Adult↗
PubMed1999

Nonpharmacologic and pharmacologic management of weight gain.

Obesity increases the risk of several serious health problems, including heart disease, type II diabetes mellitus, hypertension, and osteoarthritis. Patients taking certain psychotropic medications may gain a significant amount of weight (as much as a 5% increase in body weight within 1 to 2 months), placing them at risk for obesity. Body weight monitoring and prudent drug selection are the best approaches to preventing weight gain in patients taking psychotropic drugs. When weight gain (> 5% of initial body weight) is unavoidable, intervention counseling should begin. Nonpharmacologic measures for managing weight gain include a balanced deficit diet of 1000 calories and higher, depending on the patient's weight; 30 to 60 minutes of physical activity daily; and behavioral training to restrain excess caloric intake. Each of these measures requires a considerable commitment on the part of the patient and works best with support from the physician and weight-loss support groups. Drug therapy for weight loss is available (at present, sibutramine is the only approved appetite suppressant in the United States); however, for most patients already being treated with a psychotropic agent, the risks (such as drug interactions, adverse events, compliance problems) of adding an antiobesity agent probably outweigh the benefits. Surgical intervention for obesity should be reserved for morbidly obese patients whose disease is intractable to medical therapy.

Anti-Obesity Agents↗
PubMed1998

Hysterosalpingography with a balloon catheter versus a metal cannula: a prospective, randomized, blinded comparative study.

A prospective, randomized, blinded study was conducted to compare the use of a balloon catheter for performing hysterosalpingography (HSG) with the use of a traditional metal cannula. Sixty-one consecutive women who underwent HSG for evaluation of infertility were prospectively randomized to undergo the procedure with either a metal cannula (n = 31) or the balloon catheter (n = 30). The HSG procedure was identical in both groups. HSG using the balloon catheter, compared to the metal cannula, required significantly less fluoroscopic time (57.4 +/- 17.6 versus 75.6 +/- 40.5 s), smaller amounts of contrast medium (7.8 +/- 3.9 versus 20.1 +/- 15.8 ml), produced less pain (3.8 +/- 2.0 versus 5.6 +/- 2; on a scale of 1-10), and was easier for the physician to perform (8.8 +/- 1.1 versus 6.4 +/- 1.9; on a scale of 1-10) (P < 0.01). Eight patients (13%) were diagnosed as having proximal tubal occlusion. It was possible to offer an immediate transcervical tubal catheterization for further diagnosis and treatment of the occlusion only to the five patients with this condition from the balloon catheter group. We conclude that the balloon catheter is superior to the traditional metal cannula for performing HSG. Furthermore, if proximal tubal occlusion is diagnosed, an immediate selective salpingography and transcervical tubal catheterization can be performed without the need to replace the cannula or to reschedule the patient.

Adult↗
PubMed1992

Transcripts for the acetylcholine receptor and acetylcholine esterase show distribution differences in cultured chick muscle cells.

In situ hybridization of chick cultured muscle cells using exonic DNA probes for both AChR alpha-sub-unit and the catalytic subunit of AChE, revealed major differences in the distribution of label both over nuclei and in their surrounding cytoplasm, although some overlap in these distributions exists. For the AChR alpha-subunit there is a highly skewed distribution of labeled nuclei, with 35% of the nuclei being relatively inactive (less than 0.25 times the mean label) and approximately 10% being very heavily labeled (greater than 2.5 times the mean label). In contrast the nuclei labeled with the exonic probe for the AChE transcripts had a more Gaussian distribution, yet with some slight skewness in the direction of a few heavily labeled nuclei. There was also a difference in the cytoplasmic distribution of the label. The AChR alpha-subunit mRNA was mainly within 4 microns of labeled nuclei while the AChE mRNA was more widely distributed throughout the cytoplasm, possibly within a 10 microns rim around labeled nuclei. An intronic probe for the AChE gave the identical distribution of nuclear label to that of the exonic probe (but without any cytoplasmic label). In addition, calibration of the technique indicated that per myotube the AChE transcript is about sixfold more abundant than the AChR alpha-subunit transcript.

Acetylcholinesterase↗
PubMed1991

[Outcome of immediate management of severe head injuries].

Immediate management of severe head injuries still poses a serious challenge. 50 patients with severe head injuries (Glasgow Coma Scale, 8 or less) were treated from February 1, 1989 to April 30, 1990. The effects of age, Glasgow Coma Score at admission, CT findings, pupillary reactivity to light and intracranial pressure on outcome, were evaluated. The results of the present series match those of other studies and in some aspects the results are even superior. We attribute the high incidence of good outcome to the direct referral of the severe head injury patients, thus excluding delays at peripheral hospitals. In addition, aggressive management in the intensive care units and a broader range of indications for operation were also correlated with favorable outcome.

Brain Injuries↗
PubMed1988

An evaluation of the effect of aspartame on weight loss.

This study explores whether the addition of aspartame-sweetened foods and beverages to a low fat, hypocaloric diet enhances compliance and resulting weight loss. Fifty-nine obese (130-225% of ideal body weight), free living men and women were randomly assigned to either a Balanced Deficit Diet (BDD) or a BDD supplemented with aspartame. Over a 12-week weight loss period, volunteers attended weekly support group meetings including behavior modification training and exercise instruction. Males achieved a clinically significant weight loss (greater than 23 lb) in both study groups, while females lost an average of 12.8 lb in the control group vs. 16.5 lb in the experimental group. In both treatment groups, sleep, general energy level, level of physical activity, and feeling of well-being showed clinically meaningful improvement. This study suggests possible advantages to supplementing a BDD with aspartame-sweetened foods as part of a multidisciplinary weight loss program. The small sample size prohibits definitive conclusions but does provide the protocol for a larger, outpatient clinical trial.

Adult↗
PubMed1986

Comparative study of the configuration and the cleanliness level of root canals prepared with the aid of sodium hypochlorite and bis-dequalinium-acetate solutions.

Bis-dequalinium acetate (BDA), a quaternary ammonium compound, was introduced as a bactericidal and chemotherapeutic agent for endodontic use. This study was undertaken to compare the efficacy of this compound to 5.25% sodium hypochlorite in the cleansing and shaping of root canals. One hundred twenty freshly extracted teeth were divided into three groups. Each group was treated with the aid of the test material; saline solution was used as a control. After completion of the endodontic preparation, a silicone imprint of the canals was performed and the teeth were decalcified. The imprints were examined three-dimensionally to determine the amount of debris and canal configuration due to defective preparation and anatomic variation. No significant difference could be observed between the tested materials with respect to cleanliness and the shape of the canals. At the apical third, however, the BDA-treated canals showed more favorable results with respect to cleanliness. On the basis of the present and previous findings, it was concluded that BDA might be a favorable replacement for sodium hypochlorite as an irrigation solution.

Dental Pulp Cavity↗
PubMed1985

Multidisciplinary treatment of obesity with a protein-sparing modified fast: results in 668 outpatients.

Six hundred sixty-eight obese outpatients, 71 per cent (+/- 34) in excess of ideal weight, were enrolled in a multidisciplinary weight control program. The major components of the program included nutrition, education, behavior modification, and exercise. Rapid weight loss was accomplished using a very low calorie (less than 800 kcal) ketogenic diet. Patients adhered to the protein sparing modified fast (PSMF) for 17 +/- 12 weeks and averaged 9 +/- 17 weeks in a refeeding/maintenance program. Mean weight loss was 47 +/- 29 lb (21 +/- 13 kg) at the point of minimum weight and 41 +/- 29 lb (19 +/- 13 kg) at the end of the maintenance period. Systolic and diastolic blood pressure and serum triglycerides fell significantly in men and women. Success in weight loss was greatest in the heaviest patients, those who adhered the longest to the PSMF, and those who stayed the longest in the maintenance program.

Adult↗
PubMed1980

Distribution and activity of endogenous lectin during myogenesis as measured with antilectin antibody.

Antibodies to electrolectin, a lectin endogenous to embryonic skeletal muscle, have been used to study the distribution of electrolectin during myogenesis in L6 cells and rat primary muscle cultures. Antibody binding is highest to mononucleated cells and is low to myotubes in both systems. Binding is much lower to fibroblasts in the primary cultures. Binding appears to be on the surface of these cells, although evidence is presented for there being binding on the inside of cells as well. When observed on myotubes, binding is generally associated with highly stained patches and in some instances is near regions where fusion may be occurring, In L6 cells, binding sites can be exposed by treating mononucleated cells with trypsin. These results are discussed in terms of their possible role in myogenesis and synaptogenesis.

Animals↗
PubMed1979

Energy regulation in morbid obesity by multidisciplinary therapy.

Regulation of energy expenditure should be directed toward fat mobilization and oxidation with concomitant preservation of lean body mass. This requires a multidisciplinary approach. The key surgical component of a gastric bypass is a properly sized pouch and stoma outlet. Compliance with a diet of approximately 800 to 1200 kcal per day, limited to three small meals and two snacks is the desired result. Weight loss should average 10 to 15 pounds monthly when surgery is added to intense medical, nutritional, and behavior therapy to ensure that the weight is reduced to desirable levels.

Diet, Reducing↗