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O Kaplan

Publications and source records attributed to O Kaplan.

At least 19 recordsLinked to original sources
PubMed1992

Effect of P-glycoprotein expression on sensitivity to hormones in MCF-7 human breast cancer cells.

BACKGROUND: Data obtained from studies of primary human breast cancers and established cell lines indicate that overexpression of the MDR1 gene (also known as PGY1) is associated with decreased expression of steroid hormone receptors and increased expression of epidermal growth factor (EGF) receptors. Other study results indicate that both progestins and triphenylethylene antiestrogens may be substrates for P-glycoprotein, the product of the MDR1 gene. These findings together suggest an association between overexpression of the MDR1 gene and cross-resistance to progestin and antiestrogen therapies. PURPOSE: This study was designed to determine (a) the ability of MDR1 expression to alter tumor sensitivity to hormone therapy and (b) the role of MDR1 expression in expression of functional hormone receptors in human breast cancer. METHODS: We transduced MCF-7 cells with MDR1 complementary DNA, using a retroviral vector directing the constitutive expression of the MDR1 gene. Transduced cells (MCF-7MDR1) were examined for ability to produce P-glycoprotein, expression of steroid hormone receptors, and responsivity to antiestrogens. For comparison, we used MCF-7ADR human breast cancer cells, which overexpress MDR1 and have also lost the requirement for 17 beta-estradiol supplementation to form tumors in nude mice. We also investigated the level of EGF-R mRNA expression by using a sensitive RNase protection analysis. RESULTS: MCF-7MDR1 cells retained both estrogen receptor and progesterone receptor expression as well as sensitivity to 4-hydroxytamoxifen. Expression of the estrogen-inducible pS2 and EGF receptor genes was similar in parental MCF-7 and transduced MCF-7MDR1 cells. EGF receptor expression was increased, and pS2 expression was lost (undetectable) in MCF-7ADR cells. CONCLUSIONS: The data indicate that overexpression of the MDR1 gene alone confers a multidrug-resistant phenotype, but it does not directly result in either cross-resistance to antiestrogens or a loss of steroid hormone receptor expression. IMPLICATIONS: MCF-7MDR1 cells provide an important model for study of the interactions of cytotoxic drugs, hormones, and the MDR1 glycoprotein in human hormone-responsive breast cancer cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Complete separation of intracellular and extracellular information in NMR spectra of perfused cells by diffusion-weighted spectroscopy.

A method is outlined that completely separates intracellular and extracellular information in NMR spectra of perfused cells. The technique uses diffusion weighting to exploit differences in motional properties between intra- and extracellular constituents. This allows monitoring of intracellular metabolism, and of transport of small drugs and nutrients through the cell membrane, under controlled physiological conditions. As a first example, proton spectra of drug-resistant MCF-7 human breast cancer cells are studied, and uptake of phenylalanine is monitored.

Cell Membrane Permeability↗
PubMed1991

The multidrug resistance phenotype: 31P nuclear magnetic resonance characterization and 2-deoxyglucose toxicity.

In order to identify changes in 31P nuclear magnetic resonance (NMR) spectra associated with multiple drug resistance (MDR), a number of wild type and drug-resistant cancer cell lines were studied. The resistant cells included cells selected with various drugs, mainly Adriamycin, as well as cells transfected with the human multidrug resistance gene (MDR1 gene), which encodes P-glycoprotein. In most cases, 31P NMR spectra were significantly different from those of parental, drug-sensitive lines. The spectra of resistant cells generally indicated increased levels of ATP and phosphocreatine in the cytoplasm. These changes are compatible with the increased glucose utilization rate previously described for resistant cells. Major changes were also observed in the levels of glycerophosphocholine and glycerophosphoethanolamine. Changes in cellular metabolism reflected by 31P NMR spectra depend on the drug used to select the cells for MDR. The direction of these changes was not consistent for all cell lines studied and could not be directly attributed to expression of P-glycoprotein, suggesting that the changes may be related to alterations in metabolism and membrane function associated with other mechanisms of MDR. The results demonstrate the suitability of 31P NMR for studies of biochemical changes associated with MDR. The toxicity of 2-deoxyglucose, a glucose antimetabolite, was investigated in addition to the NMR studies and was found to be consistently higher in multidrug-resistant cells than in the parental drug-sensitive lines. For MCF-7 breast cancer cells, where several sublines with different levels of resistance were available, the toxicity was highest for the most resistant lines.

Adenosine Triphosphate↗
PubMed1991

Lymphocyte activation and phospholipid pathways. 31P magnetic resonance studies.

31P NMR spectra of perfused lymphocytes, embedded in alginate capsules and activated by interleukin-2, were remarkably different from those of control lymphocytes. The main differences were the appearance and gradual increase in phosphodiester signals, glycerophosphocholine and glycerophosphoethanolamine. These metabolic changes also occurred following perfusion with phorbol ester and after incubation with phytohemagglutinin (PHA) and were not dependent on a special growth medium. Nifedipine, a calcium channel blocking drug, inhibited the effects of phytohemagglutinin, but not of interleukin-2. There were no NMR spectral differences between peripheral lymphocytes, stimulated for 3 weeks, and tumor-infiltrating lymphocytes. Thus, sustained accelerated turnover of phosphatidylcholine and phosphatidylethanolamine is an inherent feature of the activation process. 31P NMR spectra of lymphocytes are characterized by a low signal of phosphocholine. Perfusion studies with high concentrations of choline and the use of dapsone, an inhibitor of cytidylyltransferase, indicated that choline kinase plays a key role in regulating phosphaditylcholine synthesis in human lymphocytes.

Choline↗
PubMed1991

23Na, 59Co and 2H NMR studies of experimental acute pancreatitis.

Multinuclear MR was applied to the study of experimental acute pancreatitis. A continuous increase, up to 700%, of total, NMR visible, sodium content was detected during the development of the disease through the edematous stage to necrosis. The effect of the elevation of sodium content is amplified by an increased 23Na NMR visibility during the disease. Interstitial and total water volume of pancreases were estimated using the distribution of Co(CN)3-(6) and D2O, by 59Co and 2H NMR, respectively. In healthy pancreases the interstitial compartment was found to comprise 35% of the tissue volume. In the diseased pancreases the penetration volume of Co(CN)3-(6) reached 90% of the total tissue volume, indicating extensive membrane injury. The time dependence of the 23Na NMR in the presence of the shift reagent Na7Dy(tripolyphosphate)2.3NaCl provided additional evidence of the increased permeability of the membranes in the diseased organs.

Animals↗
PubMed1991

Sleep-disordered breathing in community-dwelling elderly.

These are the final results of a survey of sleep-disordered breathing, which examined objective and subjective information from a large randomly selected elderly sample. We randomly selected 427 elderly people aged 65 yr and over in the city of San Diego, California. Twenty-four percent had an apnea index, AI, greater than or equal to 5 and 62% had a respiratory disturbance index, RDI, greater than or equal to 10. Correlates of sleep-disordered breathing included high relative weight and reports of snoring, breathing cessation at night, nocturnal wandering or confusion, daytime sleepiness and depression. Body mass index, falling asleep at inappropriate times, male gender, no alcohol within 2 hr of bedtime and napping were the best predictors of sleep-disordered breathing. Despite statistical significance, all of the associations between interview variables and apnea indices were small. No combination of demographic variables and symptoms allowed highly reliable prediction of AI or RDI.

Aged↗
PubMed1991

Periodic limb movements in sleep in community-dwelling elderly.

The prevalence of periodic limb movements in sleep (PLMS) in a randomly selected elderly sample is reported. In San Diego, 427 elderly volunteers aged 65 yr and over were recorded in their homes. Forty-five percent had a myoclonus index, MI greater than or equal to 5. Correlates of PLMS included dissatisfaction with sleep, sleeping alone and reported kicking at night. Although statistically significant, the strengths of the associations between interview variables and myoclonus indices were all small. No combination of demographic variables and symptoms allowed highly reliable prediction of PLMS.

Aged↗
PubMed1991

The management of acute cholecystitis in elderly patients.

Acute cholecystitis is a common cause of emergency room admissions in elderly patients, and may have an atypical course with serious complications and high mortality. The authors present 131 elderly patients (aged 70 and older) who were treated for acute cholecystitis. The most common complaint was right upper abdominal pain (73%), followed by fever (55%), vomiting (48%), palpable mass (22%) and jaundice (13%). Twelve per cent of the patients were in septic shock on admission. Most patients (74%) had severe concomitant disease, increasing their operative risk significantly. Patients were prepared for surgery by hydration, nasogastric drainage, and antibiotics, while imaging was performed. They were all operated on within 48 hours. The operation of choice was cholecystectomy, which was performed in 86 patients. In 45 older and high risk patients, cholecystostomy was performed. The decision to perform cholecystostomy was taken prior to the operation, and was based on the estimated operative risk. Five patients (3.8%) died postoperatively. The major cause of death was cardiovascular disorders. Major complications occurred in 14.5 per cent and minor in 23 per cent of the patients. The complication rate correlated with severe concomitant diseases and older age groups. Patients with fever and leukocytosis had a better outcome, possibly reflecting a better immunologic status. The authors conclude that aggressive preoperative preparation and judicious use of cholecystostomy as a life-saving drainage procedure can lower the mortality from acute cholecystitis in the elderly population.

Acute Disease↗
PubMed1990

Action of gossypol and rhodamine 123 on wild type and multidrug-resistant MCF-7 human breast cancer cells: 31P nuclear magnetic resonance and toxicity studies.

The action of gossypol, a polyphenolic bisnaphthalene aldehyde, on a number of drug-sensitive and multidrug-resistant cell lines, in particular MCF-7 WT and MCF-7 ADR cells, was studied and compared to the effects of rhodamine 123. 31P nuclear magnetic resonance spectra of cells exposed to low concentrations of gossypol exhibited decreased levels of ATP, markedly increased levels of pyridine nucleotides, and decreased levels of glycerylphosphocholine. The latter effect may be related to the membrane viscosity-increasing effect of gossypol, whereas changes in the levels of pyridine nucleotides are probably due to an interference with NAD- and NADP-dependent enzymes. The effect of gossypol represents a rare example of selective and differentiated changes observed in 31P nuclear magnetic resonance spectra of cells following exposure to a drug; the effect was markedly different from that of rhodamine 123, which caused ATP depletion but no changes in the levels of glycerylphosphocholine or pyridine nucleotides. Also, the effects of gossypol and rhodamine 123 on glucose metabolism in the MCF-7 WT cells were different. Thus although both drugs caused a marked elevation of glucose uptake, an increase in lactate production exceeding that of glucose consumption, indicating an inhibition of oxidative phosphorylation, was observed only in the case of rhodamine 123. Significantly, multidrug-resistant cells exhibited strong cross-resistance to rhodamine but practically no resistance to gossypol, which emphasizes the attractiveness of the latter as a potential anticancer drug. The resistance to rhodamine 123 and sensitivity to gossypol was also observed with cells transfected with the MDR1 gene, showing that the difference in toxicity is mainly due to the different response to the P-170 drug efflux pump.

Animals↗
PubMed1990

Toxicity and effects of epidermal growth factor on glucose metabolism of MDA-468 human breast cancer cells.

Epidermal growth factor (EGF) has an in vitro inhibitory effect on tumor cells which exhibit a high number of EGF receptors (EGFR). Studies were performed in order to delineate the effects of EGF on glucose metabolism of MDA-468 human breast cancer cells, which have a large number of EGFR. Glucose consumption and lactate production were found to be substantially increased in MDA-468 cells following EGF exposure, while no such effects were detected in MCF-7 breast cancer cells, which have a very low number of EGFR. When glucose levels in the growth medium were increased, the toxicity of EGF was diminished. The energetic status of MDA-468 cells perfused with growth medium containing EGF was monitored by 31P magnetic resonance spectroscopy, and no signs of compromised metabolic state or viability were noted for up to 36 h. The rate of glucose transport and phosphorylation was quantitated by 13C magnetic resonance spectroscopy, utilizing [6-13C]2-deoxyglucose, and a 97% increase was found in MDA-468 cells following EGF administration. The profound effects of EGF on glucose metabolism in cells with very high numbers of EGFR and the lack of toxicity in the perfused system may indicate that the growth-inhibitory effect is confined to the in vitro cultured cells.

Biological Transport, Active↗
PubMed1990

Information from combined 1H and 31P NMR studies of cell extracts: differences in metabolism between drug-sensitive and drug-resistant MCF-7 human breast cancer cells.

Combined analysis of both 1H and 31P NMR spectra of extracts of drug-sensitive and multidrug-resistant MCF-7 human breast cancer cells enabled quantitative comparisons between the concentrations of major metabolites, as well as of their precursors. In resistant cells high energy phosphorus compounds, phosphocreatine and ATP, and also their precursors, creatine and ADP, were elevated compared to the sensitive cells. In phospholipid metabolism, the sensitive cells showed higher phosphocholine and phosphoethanolamine concentrations than the resistant cells, but choline levels were similar. These results delineated the differences in control of metabolic pathways between drug-sensitive and drug-resistant cells.

Breast Neoplasms↗
PubMed1990

Effects of 2-deoxyglucose on drug-sensitive and drug-resistant human breast cancer cells: toxicity and magnetic resonance spectroscopy studies of metabolism.

The glycolytic inhibitor 2-deoxyglucose (2-DG) was tested as a potential chemotherapeutic agent for drug-resistant cancer cells. Previously it was found that Adriamycin-resistant human MCF-7 breast cancer cells (ADR) exhibit an enhanced rate of glycolysis compared to their parent wild-type (WT) cell line (R. C. Lyon et al., Cancer Res., 48: 870-877, 1987). We now describe a specific toxic effect of 2-DG on the ADR cells, which is more than 15-fold greater than for WT cells. Using 31P magnetic resonance spectroscopy of perfused MCF7 cells we continuously monitored the accumulation of 2-deoxyglucose 6-phosphate together with concomitant changes in other phosphate-containing metabolites. Kinetic measurements demonstrated that ADR cells accumulated 2-deoxyglucose 6-phosphate faster and to a greater extent than WT cells, while their depletion of high energy compounds (ATP, phosphocreatine) was more pronounced and became irreversible earlier. The phosphorylation of 2-DG could be followed more effectively by the use of 13C magnetic resonance spectroscopy of 2-DG enriched with 13C at C-6, since the signals of 2-DG and 2-deoxyglucose 6-phosphate are clearly resolved and, unlike 31P magnetic resonance spectroscopy, there are no other interfering signals. With the use of this technique with ADR and WT cells the rate of phosphorylation of 2-DG was found to be 11.2 x 10(-4) and 6.5 x 10(-4) mmol/min/mg protein, respectively. The results of these studies indicate that differences in the biochemistry of energy metabolism of resistant cells may make them targets for energy antimetabolites.

Antineoplastic Agents↗
PubMed1990

Differences in metabolite content between intact pancreases and their perchloric acid extracts. A 2D 1H/31P correlation NMR study.

Perchloric and hydrochloric acid extracts of intact pancreases from healthy rats and from rats with experimental acute pancreatitis were analysed using 2D 1H/31P correlation NMR spectroscopy. Major differences were found in the 2D maps between the extracts and the intact tissues. In the case of the intact diseased pancreas the prominent 31P signal at the phosphodiester region has been assigned in our previous work as lecithin/taurocholate complex. However, the signal found in the same chemical shift region in extracts of diseased pancreases as well as healthy ones, is identified here as the phosphodiester residue of oligoribonucleotides. In these extracts additional 31P signals were found and assigned as phosphomonoester and phosphodiester hydrolysis products of RNA. The amounts of these compounds, as a function of the acid concentrations were determined, and conditions for their minimization were defined.

Animals↗
PubMed1990

Proton magnetic resonance spectroscopy of small regions (1 mL) localized inside superficial human tumors. A clinical feasibility study.

It is demonstrated that the stimulated echo technique for proton magnetic resonance spectroscopy (MRS) can be used to study metabolites in volumes of interest (VOIs) as small as 1 mL localized within superficial human tumors. Access to these small VOIs is important for characterization of tissue regions within a tumor, before, during and after treatment. Spectral appearance resembles that from studies on extracts, and cell suspensions and perfused cells of several tumor types. For the first time proton MRS was used to study cancer treatment in vivo in humans, for a case of radiation treatment of squamous cell carcinoma. No spectral evidence of changed metabolism prior to reduction in tumor size was found. However, after the first period of radiation (39 Gy, 4 weeks), complete disappearance of the metabolite resonances from the spectrum was observed, while a considerable mass still remained, suggesting effective cell destruction upon treatment. Needle aspiration cytology of this mass showed absence of malignant cells, supporting this result.

Carcinoma, Squamous Cell↗
PubMed1990

Cecal volvulus.

A review of 561 cases of cecal volvulus that were published between 1959 and 1989 along with 7 new cases, was performed to characterize the clinical and laboratory profile and to evaluate the various surgical options in treating this life-threatening condition. The age and sex distribution of these patients have changed over the years and shifted toward older patients (mean, 53 years) and female predominance (female:male ratio, 1.4:1). The clinical presentation was usually of distal closed-loop small bowel obstruction. Forty-six percent of the plain abdominal radiographs were suspected for cecal volvulus, but only 17 percent were diagnostic. Barium enema had a high rate of accuracy (88 percent) and was associated with minimal complications. True volvulus was 6 times more common than bascule, and gangrenous cecum was found in 20 percent of cases. Detorsion alone and cecopexy had almost similar complications, mortality, and recurrence rates (15, 10, and 13 percent, respectively), whereas, resection, which was performed primarily for gangrenous cecum, had higher rates. However, the highest rates of complications (52 percent), mortality (22 percent), and recurrence (14 percent) were noticed after cecostomy. These data suggest that resection should be reserved for patients with necrotic cecum and that detorsion is sufficient for patients with viable cecum. Cecostomy should be abandoned.

Adolescent↗
PubMed1990

Concerning antisense inhibition of the multiple drug resistance gene.

Recently, Vasanthakumar and Ahmed reported (Vasanthakumar, G.; Ahmed, N.K., Cancer Communications 1:225-232; 1989) a complete inhibition of the multiple drug resistance gene (MDR1) in the K562/III erythroleukemia cells, using a 15 bases-long methylphosphonate oligodeoxynucleotide analog. The sequence used, however, contained three mismatches relative to the corresponding fragment of the human MDR1 gene and, hence, the results reported cannot at present be regarded as a classical antisense effect. We have made attempts to inhibit the expression of the MDR1 gene in MCF-7 human breast cancer cells selected for resistance to Adriamycin using phosphorothioate analogs of oligodeoxynucleotides. Studies with model 35S-labeled-phosphorothioates indicated poor uptake of the compounds into the cells; the radioactivity was located mainly in the soluble fraction (cytoplasm), but membranes and the nuclear fraction were also labeled. Unmodified oligodeoxynucleotides were toxic to the cells, whereas the phosphorothioates were not. The MDR1 inhibition with phosphorothioates was studied by measuring their effects on adriamycin toxicity and by immunocytochemical titration of P170. Elevation of adriamycin cytotoxicity consistent with a decreased drug resistance was observed with one antisense sequence, but the immunocytochemical assay indicated only slight inhibition of the synthesis of P170. In the wild type (drug sensitive) MCF-7 cells phosphorothioates decreased adriamycin toxicity in a sequence-independent manner. The results indicate that the effects of antisense oligodeoxynucleotides on cells are complex. Computer simulation of the secondary structure of MDR1 mRNA indicated not only extensive folding but, also, the presence of many regions not involved in intramolecular hybridization, which are of potential interest as targets for antisense oligodeoxynucleotides.

Base Sequence↗
PubMed1990

Surgical palliation combined with synchronous therapy in pancreatic carcinoma.

Palliative surgery has a role in nonresectable pancreatic carcinoma. We attempted to evaluate the efficacy of palliative surgery followed by synchronous therapy in such cases. A group of 92 patients was studied. Sixty-six patients (Group 1) with biliary obstruction underwent surgical biliary bypass. Twenty-six patients (Group 2) underwent explorative laparotomy only. Thirty patients (45.5%) in Group 1 and 10 patients (38.5%) in Group 2 received synchronous therapy consisting of 10 intravenous administrations of 5-fluorouracil (750 mg/m2) over 8 h, followed 8 h later by radiation with 400 rads repeated every 4 days. The mean survival for the entire group was 8.9 months. Those in Group 1 who received synchronous therapy had a mean survival of 13.5 months; those who did not 8.9 months (P less than 0.01). Patients in Group 2 who received synchronous therapy survived with a mean of 5.4 months, those who did not 2.7 months (P less than 0.01). Toxicity due to synchronous therapy was minimal. Of the 40 patients receiving synchronous therapy, 37 suffered from abdominal pains prior to initiation of therapy, 29 of which (78.4%) were free of pain upon completion of therapy. In nonresectable carcinoma of the pancreas, surgical palliation provides an acceptable survival. When combined with synchronous therapy, it results in prolonged survival and an ameliorated quality of life.

Adult↗