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Biomedical subjects

M H Torosian

Publications and source records attributed to M H Torosian.

At least 55 records · Page 3Linked to original sources
PubMed1986

Central venous access with occlusive superior central venous thrombosis.

Thrombotic occlusion of the entire superior central venous system is a rare complication of central venous catheterization. Three patients are presented with complete occlusion of the superior vena cava secondary to prolonged central venous catheterization. Thrombotic occlusion of the superior vena cava precludes central venous access by conventional techniques. Thoracotomy with direct catheterization of the right atrium and inferior vena cava cannulation represent alternative approaches but may be associated with significant morbidity. The present report describes a unique combined angiographic/operative technique designed to obtain central venous access with low morbidity in patients with occlusive thrombosis of the superior central venous system.

Adult↗
PubMed1986

Comparison of glucose, LCT, and LCT plus MCT as calorie sources for parenterally nourished septic rats.

Protein and energy metabolism were investigated in acutely septic rats. Rats were made septic by cecal puncture and ligation. For the next 24 h they were given one of five parenteral formulations differing only in the nonprotein calorie source. The five calorie sources were 1) glucose, 2) long-chain triglycerides (LCT), 3) a 27:73 mixture of medium- and long-chain triglycerides (M/LCT), 4) a 50:50 mixture of glucose plus LCT, and 5) a 50:50 mixture of glucose plus the M/LCT mixture. The formulations also contained amino acids at a calorie:ratio of 165:1. The results were that N retention was greater with the glucose plus LCT mixture than with glucose alone. With this mixture, N retention increased as calorie intake increased, whereas with glucose, N retention plateaued. In spite of the high glucose load given to the glucose-only groups, there was a significant reduction in endogenous fat in peripheral depots. Lipid loss was least with the glucose plus LCT combination. The M/LCT mixture given alone or with glucose resulted in significantly lower survival rates.

Amino Acids↗
PubMed1985

Enhanced tumor response to cycle-specific chemotherapy by pulse total parenteral nutrition.

Exogenous nutrient administration has been shown to significantly stimulate tumor growth in numerous animal models. The present study was performed to determine if substrate-induced alterations in tumor metabolism could be exploited to potentiate tumor response to cycle-specific chemotherapy. Following subcutaneous mammary tumor (AC-33) implantation, 55 female Lewis/Wistar rats were randomly assigned to one of three nutritional regimens for 48 hr: (1) protein-depleted chow (0.03% protein) ad lib per os, (2) standard rat chow (22.0% protein) ad lib per os, or (3) total parenteral nutrition (TPN; 18.6% dextrose/2.8% amino acids). One-half of the animals in each group received a single dose of methotrexate (5 mg/kg im) while the remaining animals received placebo (saline) injections. At sacrifice, methotrexate-treated animals receiving TPN demonstrated a significantly smaller tumor volume (0.47 +/- 0.44 cm3) compared to animals given either protein depleted chow (1.30 +/- 0.76 cm3) or standard rat chow (1.34 +/- 0.83 cm3) (P less than 0.01). In this animal model, adjuvant TPN was found to significantly potentiate tumor response to cycle-specific chemotherapy with no detectable exacerbation of host toxicity.

Adenocarcinoma↗
PubMed1984

Alteration of tumor cell kinetics by pulse total parenteral nutrition. Potential therapeutic implications.

Previous work has demonstrated that substrate-induced alterations of tumor metabolism can be exploited to potentiate tumor response to cycle-specific chemotherapy (methotrexate, Adriamycin [doxorubicin] ). This study was performed to investigate the biologic mechanism responsible for this phenomenon by determining the effect of short-term total parenteral nutrition (TPN) on tumor cytokinetics. Forty-two female Lewis/Wistar rats with subcutaneous mammary tumor implants (AC-33) underwent superior vena caval cannulation, and were randomized to receive either TPN or normal saline intravenously. Animals receiving TPN were killed at 2, 6, 12, 24, and 48 hours after initiating TPN; control animals given normal saline were killed at 0, 24, and 48 hours after randomization. At the time animals were killed tumor cytokinetic analysis was performed by flow cytophotometry. The percentage of tumor cells in S-phase was significantly increased in animals after only 2 hours of TPN (55.5 +/- 9.1%) compared with the control group (43.7 +/- 7.7%) (P less than 0.01). The ratio of sensitive/resistant tumor cells to S-phase-specific chemotherapy was effectively increased in animals receiving adjuvant TPN (1.31 +/- 0.43) compared with control animals (0.80 +/- 0.25) (P less than 0.015). This alteration in tumor cytokinetics provides one explanation for the enhanced tumor response to cycle-specific chemotherapy previously observed with pulse TPN administration.

Adenocarcinoma↗
PubMed1983

Adjuvant, pulse total parenteral nutrition and tumor response to cycle-specific and cycle-nonspecific chemotherapy.

Previous work has demonstrated that substrate-induced alterations of tumor metabolism can be exploited to enhance tumor response to a cycle-specific chemotherapeutic agent (methotrexate). This study was designed to further investigate the biologic mechanism of this phenomenon by determination of tumor response to additional cycle-specific (Adriamycin) and cycle-nonspecific (Cytoxan) chemotherapeutic agents. Significant potentiation of tumor response during adjuvant total parenteral nutrition (TPN) was observed with methotrexate and Adriamycin but not with Cytoxan. This may imply that tumor sensitization by adjuvant TPN occurs by acceleration of the growth rate of proliferating tumor cells and not by recruitment of dormant tumor cells into the cell cycle.

Adenocarcinoma↗
PubMed1980

Feeding by tube enterostomy.

Feeding by tube enterostomy is safe, economical and well tolerated by most patients. It will ameliorate or reverse the catabolic effects of protein-calorie malnutrition. Feeding tube enterostomy is indicated in patients with the combined findings: a need for long term nutritional therapy; inability to ingest adequate nutrients by mouth, and a normally functioning gastrointestinal tract. These feedings are most efficaciously delivered into the stomach and jejunum and the surgeon must be thoroughly familiar with the differences in commercial formulations prior to their use.

Duodenum↗
PubMedDate not supplied

Local recurrence of breast cancer in the stereotactic core needle biopsy site: case reports and review of the literature.

Early mammographic detection of nonpalpable breast lesions has led to the increasing use of stereotactic core biopsies for tissue diagnosis. Tumor seeding the needle tract is a theorectical concern; the incidence and clinical significance of this potential complication are unknown. We report three cases of subcutaneous breast cancer recurrence at the stereotactic biopsy site after definitive treatment of the primary breast tumor. Two cases were clinically evident and relevant; the third was detected in the preclinical, microscopic state. All three patients underwent multiple passes during stereotactic large-core biopsies (14 gauge needle) followed by modified radical mastectomy. Two patients developed a subcutaneous recurrence at the site of the previous biopsy 12 and 17 months later; one had excision of the skin and dermis at the time of mastectomy revealing tumor cells locally. In summary, clinically relevant recurrence from tumor cells seeding the needle tract is reported in two patients after definitive surgical therapy (without adjuvant radiation therapy). Often, the biopsy site is outside the boundaries of surgical resection. Since the core needle biopsy exit site represents a potential area of malignant seeding and subsequent tumor recurrence, we recommend excising the stereotactic core biopsy tract at the time of definitive surgical resection of the primary tumor.

Adult↗
PubMedDate not supplied

Correlation of lesion appearance and histologic findings for the nodes of a breast MR imaging interpretation model.

An interpretation model for evaluating magnetic resonance (MR) images of the breast was constructed that allowed differentiation of benign from malignant palpable or mammographically visible abnormalities. Architectural features define each node of the model. Investigation was subsequently made of the histologic findings in individuals within each node and of the frequency with which each histologic finding manifested as a particular architectural feature to determine whether nodal location and specific histologic findings are mutually predictive. The strongest associations were found between fibrocystic change and smooth masses, fibroadenoma and lobulated masses with nonenhancing internal septations, invasive ductal carcinoma (with or without ductal carcinoma in situ [DCIS]) and enhancing irregular or spiculated masses, invasive tubular carcinoma or radial scar and spiculated masses, medullary or colloid carcinoma and enhancing lobulated masses, invasive lobular carcinoma and the absence of a focal mass, DCIS and ductal enhancement, and DCIS (with or without invasive ductal carcinoma) and regional enhancement. Nodal location and histologic findings proved to be mutually predictive within the model; that is, the nodal location of MR imaging features within the model can be used to predict histologic findings and vice versa.

Biopsy↗
PubMedDate not supplied

Enhanced tumor response to cycle-specific chemotherapy by parenteral amino acid administration.

Forced feeding has been shown to effectively stimulate tumor metabolism in numerous animal models. Significant acceleration of tumor growth by exogenous nutrient administration is generally considered to be detrimental to the host. The present study was performed to determine if substrate-induced alterations in tumor metabolism could be exploited to enhance tumor response to cycle-specific chemotherapy. Following subcutaneous mammary tumor implantation (AC-33) and protein depletion, 39 female Lewis/Wistar rats were randomly assigned to one of four nutritional regimens for 48 hr: (1) protein-depleted food (0.03% protein) ad libitum po, (2) parenteral carbohydrate (18.6% dextrose), (3) parenteral amino acids (2.8% amino acids), or (4) total parenteral nutrition (18.6% dextrose/2.8% amino acids). Methotrexate (5 mg/kg im) was administered to all animals 2 hr after initiating these nutritional regimens. Tumor volume and host toxicity were monitored throughout the study. At sacrifice, significant reduction in tumor volume was observed in animals receiving parenteral amino acids (0.37 +/- 0.24 cm3) and total parenteral nutrition (0.25 +/- 0.18 cm3) compared to the group receiving protein-depleted food po (0.70 +/- 0.22 cm3) (p less than 0.01). In this animal model, the parenteral administration of amino acids with or without the addition of hypertonic dextrose was found to effectively potentiate tumor response to methotrexate without increasing host toxicity.

Adenocarcinoma↗
PubMedDate not supplied

Conversion of choledochojejunostomy stents to jejunal feeding tubes for postoperative enteral alimentation.

The problem of protein calorie malnutrition following major gastrointestinal surgery can be treated with central venous or enteric alimentation, with the latter being preferred. The authors describe a simple technique for the conversion of biliary stents placed after pancreaticoduodenal surgery into jejunal feeding tubes when the stenting function is no longer needed. Three illustrative cases are presented. In each case, the procedure took less than 30 min and had no associated morbidity. This technique allows early conversion from central venous to enteric alimentation without the need to create a second surgical enterostomy.

Adenocarcinoma↗
PubMedDate not supplied

Stimulation of tumor growth by nutrition support.

Controversy exists regarding the use of nutrition support in the cancer patient. Although nutrition support can clearly improve host nutritional status and restore immunoconfidence, the efficacy of nutrition support to reduce morbidity and mortality associated with antineoplastic therapy is questionable. A potential concern with the use of nutrition support in the tumor-bearing host is stimulation of primary tumor growth and metastasis. Numerous animal studies clearly demonstrate that oral and parenteral nutrition can significantly stimulate tumor cell proliferation and distant metastasis. Although cellular kinetic studies in humans have shown alterations after parenteral nutrition, objective measures of tumor growth, metastasis and tumor protein synthesis have not been affected by parenteral nutrition. This chapter summarizes the research and clinical work regarding the effect of nutrients on tumorigenesis, primary tumor growth, and metastasis in both animal and human tumors.

Animals↗
PubMedDate not supplied

Effect of protein-calorie malnutrition on methotrexate pharmacokinetics.

Methotrexate toxicity is increased in protein-calorie malnutrition. The influence of protein-calorie malnutrition on the pharmacokinetics and binding of methotrexate (MTX) and the formation of its major hepatic metabolite, 7-hydroxy-methotrexate was examined in 30 adult, female Lewis rats. Animals were randomized to receive either a standard diet (22.0% protein; 4.20 kcal/g) or a protein-depleted diet (PD) (0.03% protein; 4.27 kcal/g) ad libitum for 35 days. Animals were then separated into two groups for either methotrexate pharmacokinetics (n = 20) or serum protein binding (n = 10) studies. The mean weight loss in the PD group was 26% of their initial body weight, as compared with a 29% weight gain in the control group. In the protein binding study, a significant decrease in serum albumin (19%), uncorrected creatinine clearance (38%), and free fraction of MTX (15%) was found in the PD group. All animals in the pharmacokinetic study received a single intraperitoneal injection of MTX (10 mg/kg), and serum MTX and 7-hydroxy-methotrexate concentrations were determined using a specific, reversed phase, high-performance liquid chromatography assay. The mean AUC0-3 in the PD group was 43.6 +/- 3.9 micrograms/mL per hour compared with 15.8 +/- 1.1 micrograms/mL per hour in the control group (p < .001). The time to peak and the peak serum concentrations were significantly greater in the PD animals, which indicated delayed absorption and clearance. These results suggest that the increase in MTX toxicity observed in protein-calorie malnutrition is associated with a decrease in MTX clearance, and is not related to changes in protein binding or formation of 7-hydroxy-methotrexate.

Animals↗
PubMedDate not supplied

Growth hormone and prostate cancer growth and metastasis in tumor-bearing animals.

Growth hormone has been shown to stimulate muscle protein synthesis, improve nitrogen balance and promote wound healing in a variety of catabolic states. Its role in the tumor-bearing host is controversial because of its potential to stimulate tumor growth. Twenty-seven Lobund/Wistar rats bearing a subcutaneous prostate tumor implant (PA-III), were randomized to receive growth hormone (1,000 mU/kg/day) or placebo (saline) in the protein-fed and protein-depleted states. Body weight, primary tumor growth and tumor metastasis were assessed to determine the effect of growth hormone and dietary protein intake on these parameters. Growth hormone significantly increased carcass weight in protein-fed animals and reduced carcass weight loss in protein-depleted animals. No stimulation of primary tumor growth occurred and tumor:body weight ratio was similar in all treatment groups. Inhibition of spontaneous pulmonary metastasis occurred following growth hormone therapy in protein-fed and protein-depleted animals. Thus, in this tumor model, growth hormone was found to support host growth selectively and inhibit pulmonary metastasis and may be used as an adjunct to treat cancer cachexia effectively in the future.

Animals↗
PubMedDate not supplied

Myofibroblastoma associated with bilateral gynecomastia: a case report and literature review.

Myofibroblastoma of the breast is a recently recognized benign mesenchymal mammary tumor that typically occurs as a unilateral, solitary lesion. Myofibroblastomas are well-circumscribed, unencapsulated tumors characterized by spindle cells in fascicles which exhibit varying degrees of myogenic and fibroblastic differentiation. Our case reports a mammary myofibroblastoma occurring in an 82-year-old male with gynecomastia and reviews the reported incidence of this benign spindle cell tumor in the world literature.

Aged↗
PubMedDate not supplied

Evidence for selective use of bone scans in early stage breast cancer.

To determine the usefulness of bone scans in detecting metastatic disease in women with early stage breast cancer, records of 193 patients who had bone scans preformed and underwent breast conservation therapy at a single institution were reviewed. Patients with invasive T1 or T2 breast carcinomas were eligible for this study; patients with a true positive bone scan were excluded from conservation therapy and, thus, were excluded from this study. The incidence of false positive bone scans in this study population was 32.6% (63/193 patients). Patients over 50 years of age had a significantly greater incidence of false positive bone scans (p<0. 05). In the 63 patients with false positive bone scans, 101 radiographs were performed to exclude metastatic disease in areas of increased uptake identified on bone scan. No significant difference in the rate of false positive bone scans was seen in relation to tumor size, pathologic or clinical nodal status or hormone receptor activity of the primary tumor. Thus, selective use of bone scans is advocated in patients with early stage (T1 or T2) breast cancer.

Adult↗