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Biomedical subjects

D Blumberg

Publications and source records attributed to D Blumberg.

35 records · Page 2Linked to original sources
PubMed1995

Energy depletion in the liver and in isolated hepatocytes of tumor-bearing animals.

Cancer cachexia has a great impact on morbidity and mortality in patients undergoing surgery. Failure to maintain lean tissue against tumor-induced hypermetabolism results in cumulative weight loss and ultimate failure of the host. Cellular free energy is among the factors that regulates metabolic pathways and may be altered in the tumor-bearing state. We studied in-vivo and in-vitro ATP levels and metabolic parameters in Fischer rats bearing a methylcholanthrene-induced sarcoma to elucidate the energy state. Tissue ATP was measured in freeze-clamped liver and muscle in 15 tumor-bearing rats (TBR) at different tumor burdens and their pair-fed controls (CTR) by bioluminescence assay. Plasma metabolites, hormones, and enzymes were determined in the same animals. Liver ATP level was lower in TBR with a 5% tumor burden: 3.07 +/- 0.56 (SE) nmole/mg tissue vs CTR: 5.33 +/- 0.60 (P < 0.05), 10% TBR: 2.48 +/- 0.54 vs CTR: 4.05 +/- 0.63 (n.s.), and 20% TBR: 1.91 +/- 0.21 vs CTR: 3.86 +/- 0.40 (P < 0.01). Muscle ATP was not different between TBR and CTR. This progressive loss of liver ATP was associated with decreased plasma insulin level (P < 0.001) and with increased alkaline phosphatase level (P < 0.01) by multiple regression. In vitro, hepatocytes were isolated from 8 TBR and 8 CTR by in-situ liver perfusion with collagenase and the cellular ATP was measured before and after 60 min incubation with glucogenic substrates. Hepatocytes from TBR decreased ATP by 42% (P < 0.05) in 10 mM lactate with higher gluconeogenesis, while control hepatocytes maintained the ATP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1995

Altered glutathione metabolism in the tumor-bearing state.

BACKGROUND: Because glutathione (GSH) appears to be important for tumor growth and many tumors contain the capacity (gamma-glutamyltranspeptidase) to transport GSH, we examined GSH metabolism in MCA sarcoma-bearing rats (TB). METHODS: Tumor, liver skeletal muscle, kidney, and serum were collected from 47 MCA sarcoma (TB) rats and 26 normal (CTL) rats. Amino acids, GSH, gamma-glutamylcysteine synthetase (GCS), and gamma-glutamyl transpeptidase (GGTP) were determined. RESULTS: Significant activity of GGTP (117.8 +/- 16.0 mU/min/mg protein) was present in tumors. Liver GCS activity (nanomolar per hour per milligram protein) in TB rats (106.6 +/- 37.7) was increased (p < 0.01) compared with CTL rats (57.5 +/- 12.3) and correlated positively with tumor burden (R = 0.77). Muscle GGTP was decreased (p = 0.001) in TB rats (1.7 +/- 1.1) compared with controls (6.8 +/- 1.1). Serum GSH concentrations (microM) were lower (p < 0.05) in TB rats (14.97 +/- 1.72) versus control rats (16.82 +/- 1.54) and correlated negatively with tumor burden (R = -0.83). CONCLUSIONS: In this tumor-bearing model, tumor has significant capacity (GGTP) for the uptake of GSH. Serum GSH is depleted in TB rats and correlates negatively with tumor burden. Liver GCS is increased in TB rats and skeletal muscle GGTP is decreased, which may preferentially benefit the tumor by increasing the bioavailability of glutathione for its own use.

Amino Acids↗
PubMed1995

Thymoma: a multivariate analysis of factors predicting survival.

BACKGROUND: Despite complete surgical excision, malignant thymomas often recur with resultant death. We reviewed our series to determine which factors independently predict survival after surgical resection. METHODS: A retrospective analysis of patients operated on for thymoma between 1949 and 1993 at Memorial Sloan-Kettering Cancer Center was performed. Clinical data were collected from chart review. Only patients with a pathology report confirming the diagnosis of thymoma were included in this analysis. Kaplan-Meier survival curves were generated and comparisons of survival analyzed by log rank test. Multivariate analysis was performed by the Cox proportional hazard model. RESULTS: One hundred eighteen patients with thymoma underwent operation. There were 86 complete resections (73%), 18 partial resections (15%), and 14 biopsies (12%). By Masaoka staging, 25 patients were stage I (21%), 41 stage II (35%), 43 stage III (36%), and 9 stage IVa (8%). Overall survival was 77% at 5 years and 55% at 10 years. Tumor recurred in 25 (29%) of 86 completely resected thymomas. Stage of disease (p = 0.03) was the only independent prognostic factor affecting recurrence. By multivariate analysis, stage (p = 0.003), tumor size (p = 0.0001), histology (p = 0.004), and extent of surgical resection (p = 0.0006) were independent predictors of long-term survival. CONCLUSIONS: Patients with stage I disease require no further therapy after complete surgical resection. Neoadjuvant therapy should be considered for patients with large tumors and invasive disease.

Combined Modality Therapy↗
PubMed1995

Pulmonary artery perfusion of doxorubicin with blood flow occlusion: pharmacokinetics and treatment in a metastatic sarcoma model.

BACKGROUND: We compared pharmacokinetics, toxicity, and treatment efficacy of pulmonary artery perfusion of low-dose doxorubicin with blood flow occlusion to intravenous doxorubicin injection in a metastatic sarcoma model in the rat. METHODS: Animals received left pulmonary artery perfusion with 0.1, 0.2, or 0.5 mg/kg doxorubicin at a rate of 0.1 mL/min for 1 minute with 20 minutes of blood flow occlusion. Doxorubicin levels of the lung, heart, and serum were assayed. Body weights after treatment were recorded and right pneumonectomy was performed. The results were compared with those in rats that received 5 mg/kg doxorubicin by intravenous injection or the saline group. Pulmonary sarcoma metastases were treated with 0.5 mg/kg doxorubicin through lung perfusion or intravenously, or with saline solution. RESULTS: Doxorubicin levels in the lung, heart, and serum were 112.1 +/- 9.2 micrograms/g, 1.7 +/- 0.2 microgram/g, and 0.3 +/- 0.1 microgram/mL in the group with 0.5 mg/kg doxorubicin perfusion, versus 24.8 +/- 1.9 microgram/g, 10.1 +/- 1.3 microgram/g, and 0.7 +/- 0.2 microgram/mL in the intravenous group (p < 0.05). Animals had normal growth patterns and survived after right pneumonectomy in the perfused group, whereas the intravenous group failed to thrive. No tumors were found or a significant reduction in nodules was noted in the lungs treated with perfusion as compared with untreated right lungs or the intravenous and saline groups. CONCLUSION: This chemotherapy model has important pharmacokinetic advantages and causes an increased treatment response for pulmonary metastatic sarcoma with minimal systemic and local toxicity as compared with systemic doxorubicin administration.

Animals↗
PubMed1995

Interleukin-6 stimulates gluconeogenesis in primary cultures of rat hepatocytes.

Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1 have been shown to stimulate the synthesis of acute-phase proteins; however, few studies have examined the effect of these cytokines on gluconeogenesis. We investigated the effects of these cytokines on gluconeogenesis in primary cultures of rat hepatocytes. Incubation of hepatocytes for 24 hours with TNF-alpha or IL-1 alpha did not affect gluconeogenesis. Hepatocytes incubated with 100 pmol/L and 1 nmol/L IL-6 had a dose-dependent increase (P < .05) in gluconeogenesis (2.6 +/- 0.1 and 3.2 +/- 0.1 pmol/10(6) cells/min, respectively) as compared with controls (2.0 +/- 0.1).

Animals↗
PubMed1995

Imaging real-time neurite outgrowth and cytoskeletal reorganization with an atomic force microscope.

An atomic force microscope was used to image the morphology and structural reorganization of rat NIH/3T3 fibroblasts and PC-12 cells growing in petri dishes. NIH/3T3 fibroblasts had a uniform morphology and an extensive cytoskeletal network. Cell thickness varied from approximately 2-3 microns above the nucleus to approximately 20-30 nm over the distal processes, and cytoskeletal fibers as small as 30 nm wide were observed. Imaging over an extended period of time showed a limited degree of cytoskeletal reorganization. Localized force dissection did not induce significant retraction of cellular processes and immediate cell death. Differentiating PC-12 cells with a neuronal phenotype had a nonuniform morphology, abundant cytoskeletal elements, neuritic processes, and growth cones. The cell thickness varied from approximately 5-8 microns over the nucleus to approximately 100-500 nm over the neuritic processes; growth cones approximately 50-700 nm wide and end structures approximately 30-150 nm wide were visible. Repeated imaging showed reorganization of the growth cone, especially the appearance and disappearance of beadlike features and fibrous organization. Thus an atomic force microscope can be used for high-resolution real-time studies of the dynamic subcellular mechanisms that drive cell behavior.

3T3 Cells↗
PubMed1995

Rapid and efficient gene transfer in Human hepatocytes by herpes viral vectors.

Retroviral vectors have been widely studied as vehicles for hepatocyte gene therapy, but they are limited by an inability to infect nondividing cells and the need for prolonged cell culture. Two replication deficient herpes simplex viral vectors (HSV) were constructed with the marker genes lac-Z/beta-galactosidase (HSVlac) or human-growth hormone (HSVhGH) to determine the efficiency of HSV gene transfer into adult human hepatocytes. Hepatocytes were isolated by collagenase perfusions and density centrifugation from liver wedge biopsy specimens obtained from six patients. After exposure to HSV (0, 50,000 and 500,000 viral particles/ 10(6) hepatocytes) for 20 minutes, 1 hour, or 2 hours, the hepatocytes were washed and placed in culture. Hepatocytes transduced with HSVlac were fixed at 24 hours and histochemically stained with X-gal, and media from HSVhgh-transduced cells were assayed at 48 hours by radioimmunoassay for hGH. After a 20-minute exposure at a multiplicity of infection of 0.5 (1 viral particle per 2 hepatocytes), greater than 35% of the hepatocytes expressed the lac-Z gene ( > 70% efficiency). hGH was also detected in the media from HSVhGH-transduced cells, showing that proteins coded for by foreign cells are not only expressed by transduced cells but are also secreted. Isolated liver perfusions using HSVlac were also performed in Fischer rats. A 20-minute isolated perfusion using 5 x 10(6) viral particles resulted in expression of the beta-galactosidase gene in the rodent livers 72 hours later without histological signs of tissue injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Acute metabolic effects of human recombinant tumor necrosis factor beta in the rat.

BACKGROUND: Cancer cachexia is associated with several alterations in host metabolism, including hypoaminoacidemia and an increase in gluconeogenesis (GLC) and lipolysis. Tumor necrosis factor beta (TNF beta), a lymphokine released by mitogen-activated T lymphocytes and several cancer cell lines, causes an increase in lipolysis in 3T3L1 adipocytes. Since little is known about the metabolic effects of TNF beta in vivo, we examined its acute effects in the rat. METHODS: Twenty-eight male Fischer rats were injected intraperitoneally with TNF beta (250 micrograms/kg) or saline (CTL), and after 4 h, isolated hepatocytes were obtained (by in situ collagenase liver perfusion [n = 12]) or aortic blood was collected (n = 16). Hepatocytes were incubated with 10 mM alanine (ALA) or 10 mM lactate (LAC), and glucose production was measured. Rates of GLC (nmol glucose/10(6) cells/min) were determined by linear regression. Plasma lactate, glucose, insulin, and amino acids (AA) (nmol/ml) were measured, and values were expressed as means +/- SEM. Comparisons between groups were made by unpaired t test or Mann-Whitney U test, and significance was defined as p < 0.05. RESULTS: TNF beta caused a 130% increase in gluconeogenesis from alanine (2.7 +/- 0.5 vs 1.2 +/- 0.2 nmol glucose/10(6) cells/min, TNF vs CTL), and a 60% increase from lactate (7.5 +/- 1.0 vs 4.6 +/- 0.5 nmol glucose/10(6) cells/min, TNF vs CTL). Plasma insulin levels in TNF treated rats were 1.2 +/- 0.2 ng/ml compared to 1.1 +/- 0.2 ng/ml in CTL. Total amino acid levels in TNF treated rats were 3,175 +/- 111 nmol/ml compared to 3,190 +/- 103 nmol/ml in CTL. CONCLUSION: In vivo TNF beta causes an increase in hepatic gluconeogenesis from alanine and lactate with no change in plasma insulin or amino acids.

Amino Acids↗
PubMed1994

Isolated single-lung perfusion with TNF-alpha in a rat sarcoma lung metastases model.

We conducted a trial of isolated lung perfusion using tumor necrosis factor (TNF) in an experimental sarcoma lung metastasis model. In an in vitro experiment, methylcholanthrene-induced sarcoma cells were incubated for 48 hours with 42 micrograms/mL of either human or murine TNF. Controls were incubated with Hank's balanced salt solution. In an in vivo experiment, 23 F344 rats were injected with 10(7) methylcholanthrene-induced sarcoma cells. On day 7, 4 animals were perfused with 210 micrograms of murine TNF, 5 animals were perfused with 420 micrograms of murine TNF, 10 animals underwent isolated lung perfusion with 420 micrograms of human TNF, and 4 animals were injected systemically with 420 micrograms of human TNF. Animals were sacrificed on day 14 and the lung nodules counted. The cells incubated with murine TNF exhibited a 21% decrease in growth (p = 0.07); cells incubated with human TNF showed a 37% decrease in growth (p < 0.05). Animals perfused with 210 micrograms/mL of murine TNF and animals treated by systemically administered human TNF showed no tumor response. Animals perfused with 420 micrograms/mL of murine TNF had 7.8 +/- 14.2 nodules on the left lung and 58.5 +/- 66.0 nodules on the right lung (p = 0.07). Animals perfused with 420 micrograms/mL of human TNF had 21.7 +/- 18.3 nodules on the left lung and 91.7 +/- 66.2 nodules on the right lung (p < 0.01). On the basis of these findings, we conclude that isolated lung perfusion with TNF can be done safely in the rat and is effective in decreasing the growth of sarcoma lung metastases.

Animals↗
PubMed1993

Tolbutamide inhibits gluconeogenesis in the tumor-influenced hepatocyte.

The tumor-bearing state is associated with an increase in gluconeogenesis which may contribute to the development of cancer cachexia. The purpose of this study was to determine if tolbutamide, a drug known to decrease gluconeogenesis in diabetes, could decrease gluconeogenesis in hepatocytes isolated from tumor-bearing rats. Hepatocytes from 24-hr fasted normal and methylcholanthrene-induced sarcoma-bearing rats (5-10% tumor burden) were isolated by in situ collagenase liver perfusion. Hepatocytes (n = 12 samples) from non-tumor-bearing (NTB) controls and tumor-bearing (TB) rats were incubated with lactate (10 mM) and alanine (10 mM) with and without 1 mM tolbutamide. Supernatant glucose concentration was measured at 30-min intervals for 2 hr. Rates of gluconeogenesis (+/- standard error) were calculated by linear regression and are expressed as nmole glucose/10(6) cells/min. Comparisons were made by two-way analysis of variance and significance defined as P < 0.05. TB hepatocytes had an increased rate of gluconeogenesis (P < 0.0001) from alanine and lactate (3.8 +/- 0.30 and 2.2 +/- 0.10, respectively) compared with NTB hepatocytes (0.66 +/- 0.10 and 1.2 +/- 0.04, respectively). TB hepatocytes treated with tolbutamide had a decreased (P < 0.0001) rate of gluconeogenesis from alanine and lactate (3.1 +/- 0.10 and 1.1 +/- 0.10, respectively) compared with untreated TB hepatocytes (5.3 +/- 0.10 and 2.1 +/- 0.10, respectively). Tolbutamide inhibits gluconeogenesis from lactate and alanine in tumor-influenced hepatocytes.

Alanine↗
PubMed1992

Juvenile autoimmune thyroiditis and mitral valve prolapse.

An increased incidence of mitral valve prolapse (MVP) has been reported in adult patients with autoimmune thyroid disease. The aim of this study was to assess the incidence of MVP in children and adolescents with juvenile autoimmune thyroiditis (JAT). Cardiac echo studies using M-mode, 2D, and Doppler examinations were performed on 23 patients (21 females, 2 males). The patients were studied at a median age of 12 years (range 5-20 years). Only one patient was found to have evidence suggestive of MVP, an incidence (4.3%) similar to that seen in the normal pediatric population. We, therefore, conclude that the incidence of MVP in children and adolescence with JAT is not increased.

Adolescent↗
PubMed1992

Vesamicol binding to subcellular membranes that are distinct from catecholaminergic vesicles in PC12 cells.

We have examined PC12 cells for the localization of binding sites for vesamicol [l-2-(4-phenylpiperidino) cyclohexanol], a compound that has previously been shown to bind to cholinergic vesicles and to inhibit the uptake of acetylcholine. Initial studies presented in this article demonstrate the existence of a specific, saturable vesamicol binding site in PC12 cells. Subsequent experiments show that these binding sites reside in a membrane population that is distinct from catecholamine-containing compartments with respect to density and antigenic composition. In particular, vesamicol binding compartments have a lower density than catecholaminergic vesicles and, unlike these latter vesicles, do not appear to contain the vesicle-specific proteins synaptophysin and SV2 as part of the same membrane. These results suggest that vesicular transport proteins for acetylcholine and catecholamines are differentially sorted to distinct membrane compartments in PC12 cells.

Animals↗
PubMed1991

Suppression of the pituitary-gonadal axis in children with central precocious puberty: effects on growth, growth hormone, insulin-like growth factor-I, and prolactin secretion.

To assess further the relationship between gonadal sex steroids and PRL, GH, and insulin-like growth factor-I (IGF-I) secretion and to help clarify the mechanism underlying the pubertal growth spurt, we studied 11 children (10 girls) with central precocious puberty before and during gonadal suppression with the GnRH agonist (GnRH-a) leuprolide acetate. Nocturnal sampling for plasma levels of GH and PRL, GH response to GH-releasing factor-(1-44), and plasma IGF-I levels were determined before and 3-6 months after pituitary-gonadal suppression. Treatment caused a significant decrease in the LH and FSH responses to GnRH (P less than 0.01) and the plasma concentration of estradiol (P less than 0.05). The patients' mean height velocity SD score for chronological age, initially 3.8 +/- 1.9, decreased significantly to 0.9 +/- 0.9 with treatment (P less than 0.005). Nocturnal GH secretion (mean GH concentration, sum of GH pulse areas, sum of GH pulse amplitudes, and GH pulse frequency) and mean IGF-I levels (1.38 +/- 0.6 vs. 1.72 +/- 0.34 U/mL) were not significantly altered by treatment. However, the mean peak GH response to GH-releasing factor-(1-44) was 29.2 +/- 6.8 micrograms/L before treatment and declined significantly to 17.7 +/- 3.4 micrograms/L after gonadal suppression (P less than 0.05). PRL secretion was similar before and after GnRH-a-induced suppression. These results indicate that the decrease in height velocity noted during GnRH-a treatment occurred independently of changes in nocturnal GH secretion and IGF-I levels. These data are consistent with the premise that sex steroids can modulate growth by a direct action on skeletal growth.

Antineoplastic Agents↗
PubMed1989

Re-expression of 117 antigen, a cell surface glycoprotein of aggregating cells, during terminal differentiation of Dictyostelium discoideum prespore cells.

117 antigen is a glycoprotein expressed on the surface of D. discoideum cells at aggregation. It then disappears and is later re-expressed on the surface of a subpopulation of cells at culmination, the terminal differentiation stage (Sadeghi et al. 1987). A cDNA clone was used to show that the appearance of cell surface 117 antigen accurately reflects the expression of the 117 gene as measured by mRNA levels. It was also shown that during multicellular development there is a reciprocal relationship between the levels of 117 mRNA and the mRNA which codes for prespore surface glycoprotein, PsA. Dual parameter flow cytometry was used to demonstrate that the 117 antigen is found on the surface of maturing prespore cells after the PsA glycoprotein disappears, but that it is not found on mature spores. Using three monoclonal antibodies which identify respectively 117 antigen, PsA, and MUD3 antigen (a spore coat glycoprotein--probably Sp96), two new stages of final spore maturation were defined. These results indicate that there is a recapitulation of at least one aggregative cell surface glycoprotein in the prespore subpopulation of cells as they rise up the stalk during final spore development. This raises the possibility that culmination, which involves complex three dimensional morphogenetic movements not unlike those observed during animal embryogenesis, involves components of the two-dimensional pattern seen during aggregation.

Antigens, Differentiation↗