Perspectives of leprosy patients on MDT services after integration of NLEP functions into primary health care

Sixty-five leprosy patients residing in rural Digapahandi block of Ganjam district were studied during July-August 2001 in order to ascertain their perspectives regarding different MDT services after NLEP functions were integrated into primary health care (PHC) in Orissa after September 1999. They included 43.08% multibacillary (MB) cases and 61.92% paucibacillary (PB) cases. Assessment was done by personal interviews of adult patients and the parents of child cases after verification of their treatment cards at the sub-centre. Patient's knowledge regarding the availability of MDT services under PHC services and utilization of these services were highlighted. Influence of different socio-demographic factors was also studied. Basing on the study results, recommendations were made for sustained NLEP functions through PHC in order to improve the utilization of MDT services, which will help in the elimination of leprosy.

Distribution of HCH and DDT in the coastal marine environment of Mumbai, India

Organochlorine pesticides (OCPs) in sediment, water and biota samples from the coastal marine environment of Mumbai were analysed to elucidate their distribution in various environmental compartments. HCH isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites were the predominantly identified compounds in all the samples. High ratios of DDT to dichlorodiphenyldichloroethylene (DDE) were found in seawater samples. This indicates the presence of a significant source of DDT in this region. In sediment samples, the gamma-isomer contributed almost 55% to the total HCH, indicating a high affinity of the gamma-isomer towards the sediment. The levels of organochlorines in fish obtained from this region were found to be lower than the levels of organochlorines in fish in temperate regions.

Persistent organochlorine pesticide residues in milk and dairy products in India

Monitoring of milk and dairy product samples of various brands from different cities in Maharashtra, India, was carried out to determine if there is any contamination due to organochlorine pesticide residues. The measurements were made using a gas chromatograph-electron capture detector system. Trace levels of DDT and HCH were detected in the samples. Total HCH levels in milk and milk product samples were lower than total DDT levels, which could be attributed to earlier extensive antimalaria sanitary activities. Butter had higher levels of DDT than cheese and milk powder. All levels of organochlorine pesticide residues in milk and milk products were well below the maximum permissible limits given by the FAO/ WHO. More importantly, as compared with an earlier report, present levels of the contaminants are substantially lower, which indicate the gradual phase out of these compounds.

Assessment of risk to public health posed by persistent organochlorine pesticide residues in milk and milk products in Mumbai, India

The risk posed by the presence of organochlorine pesticides in milk and milk products was estimated for the population of Mumbai. To determine the levels of organochlorine pesticides in milk and milk products, a monitoring study was carried out in and around Mumbai City. 520 samples of milk and milk products of different brands were considered in this study. A survey was also conducted to determine the mean daily consumption of milk and milk products by different age groups and this data was used to evaluate the daily exposure to the public. Non-cancer effects were evaluated by comparing the predicted exposure distributions to the published guidance values. For chemicals identified as potential human carcinogens, cancer risk was evaluated using standard methodology. The majority of the chlorinated pesticides identified in the milk and milk product samples studied were found to be at levels which do not pose unacceptable risks to the public, with the exception of alpha-HCH. The cancer risk estimated for this chemical slightly exceeds the US EPA guidance value.

Gas exchange of OCPs across the air-water interface at the creek adjoining Mumbai harbour, India

The concentrations of organochlorine pesticides (OCPs) such as hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDT) and its metabolite (DDE) and endosulfans were determined in air and water in order to estimate the magnitude and direction of gas flux across the air-water interface at the creek adjoining Mumbai harbour, India. The range of HCH residues in air was found to be between 1.0 and 22.5 pg m(-3) and that in sea-water was between 1.7 to 34.4 ng l(-1) DDT and its metabolite (DDE) residues in air ranged between 2.1 and 80.8 pg m(-3) and in sea-water between 1.4 to 19.2 ng l(-1). The concentrations of beta-endosulfan in air and sea-water samples were found to be 1.0-1.6 pg m(-3) and 1.0-2.6 ng l(-1) respectively. The HCHs revealed positive values of the fluxes (1.001 microg m(-2) d(-1) for alpha-HCH, 0.107 microg m(-2) d(-1) for beta-HCH and 0.455 microg m(-2) d(-1) for gamma-HCH) indicating the tendency to transfer these contaminants from water to air. This implies that the marine water bodies principally act as a source of HCHs. The fluxes for DDTs (p,p'-DDE and p,p'-DDT) also follow the same pattern as HCHs and show high positive values (1.698 microg m(-2) d(-1) for DDE and 2.422 microg m(-2) d(-1) for DDT). The present study suggests the active transfer of these dissolved OCPs into the atmosphere due to volatilization.

A comparison of frailty and other models for bivariate survival data

Multivariate survival data arise when each study subject may experience multiple events or when study subjects are clustered into groups. Statistical analyses of such data need to account for the intra-cluster dependence through appropriate modeling. Frailty models are the most popular for such failure time data. However, there are other approaches which model the dependence structure directly. In this article, we compare the frailty models for bivariate data with the models based on bivariate exponential and Weibull distributions. Bayesian methods provide a convenient paradigm for comparing the two sets of models we consider. Our techniques are illustrated using two examples. One simulated example demonstrates model choice methods developed in this paper and the other example, based on a practical data set of onset of blindness among patients with diabetic Retinopathy, considers Bayesian inference using different models.

Electromagnetic field in and around the campus of Jawaharlal Nehru University, New Delhi

We have surveyed the levels of magnetic field in the open environment around the high-tension lines as well as in the domestic and laboratory environment in the JNU campus. Measurements were made in the direction of most likely access, and from the surface of the appliances. The data so obtained are analyzed and compared with some quoted in the literature. It is hoped that the results will be useful for epidemiological studies in determining the criteria for safe human exposure.

5-[125I]iodo-2'-deoxyuridine in the radiotherapy of brain tumors in rats

Glial neoplasms of the human central nervous system have defied treatment, in part because of the limited selectivity of available cytotoxic agents. The thymidine analog 5-iodo-2'-deoxyuridine radiolabeled with the Auger electron emitter 125I (125IUdR) is highly toxic to dividing cells when it is deoxyribonucleic acid incorporated, but it is relatively innocuous when located outside the nucleus. Previous studies have shown that 125IUdR has significant antineoplastic potential against mammalian cells in vitro and direct administration of 125IUdR is effective therapy for ovarian ascites tumors in mice and neoplastic meningitis in rats. Studies using external gamma imaging and autoradiography have also shown that direct intratumoral administration of 123IUdR/125IUdR into intracerebral 9L gliosarcomas in rats results in selective uptake of the radionuclide into tumor cells. Based on these encouraging results, we have evaluated the therapeutic potential of 125IUdR in rats bearing intracerebral 9L gliosarcomas.

METHODS

Iodine-125-IUdR was infused intracerebrally over a 2-day period into rats bearing 1-day-old 9L tumors and over a 6-day period into animals with 9-day-old 9L tumors; equimolar concentrations of 127IUdR were infused into control animals. Tumor growth was monitored by contrast-enhanced 1H MRI and animal survival was followed over time.

RESULTS

Intracerebral tumors (3-7 mm) were readily detected by MRI. Tumor-bearing rats treated with 127IUdR succumbed within 17-24 days, whereas tumor-bearing animals treated with 125IUdR survived significantly longer, and 10%-20% of the animals were cured of tumors.

CONCLUSION

These data substantiate the antineoplastic potential of 5-[125I]iodo-2'-deoxyuridine and indicate that it may be a useful agent for the therapy of solid tumors that are accessible to direct radiopharmaceutical administration.

Continuous detection of radiation or metal generated hydroxyl radicals within core chromatin particles

PURPOSE

The aim of this work was to adapt a recently developed fluorometric method for use in the detection of hydroxyl radical (HO.) generated in the immediate vicinity of chromatin core particles reconstituted from pUC19 plasmid DNA and isolated core histones.

MATERIALS AND METHODS

The procedure followed involves labelling nucleosomal histones with SECCA, a non-fluorescent coumarin derivative that generates the fluorescent 7-hydroxy-SECCA after reaction with HO.. Core particles are formed using histones and pUC19 DNA in a salt-dialysis procedure.

RESULTS

Electron microscopy and micrococcal nuclease digestion are consistent with successful formation of core particles. No significant differences between core particle formation in the unlabelled and SECCA-labelled samples were detected. Exposure to HO. generated by radiation or copper--ascorbic acid--hydrogen peroxide results in a gradual induction of fluorescence. Studies using dimethyl sulphoxide (DMSO) demonstrate that, unlike HO. produced by radiation, the majority of HO. generated by copper--ascorbic acid--hydrogen peroxide occurs primarily in the immediate vicinity of core particles and DNA and cannot be scavenged.

CONCLUSIONS

The present procedure demonstrates the feasibility to quantitate HO. generated by several agents in the immediate vicinity of nucleosomes (chromatin-associated HO.) or associated with specific regions within the genome.

Strand breaks after the decay of iodine-125 in proximity to plasmid pBR322 DNA

To elucidate the kinetics of DNA strand breaks caused by low-energy Auger electron emitters in proximity to DNA molecules, we synthesized (125)I-labeled 2-iodoacridine (2-(125)IA), which intercalates with DNA, and 4-iodoacridine (4-(125)IA), which does not. Supercoiled DNA from pBR322 plasmid, labeled with 3H, was purified and incubated with 2-(125)IA or 4-(125)IA in aqueous solution. Reaction mixtures were stored at 4 degrees C to accumulate radiation dose from the decay of (125)I, and DNA was resolved by gel electrophoresis into supercoiled (DNA-I), nicked-circular (DNA-II) and linear (DNA-III) forms, representing undamaged DNA, single-strand breaks (SSBs) and double-strand breaks (DSBs), respectively. Gamma irradiation from an external (137)Cs source led to an exponential decrease in DNA-I with a D0 value of 10.8 +/- 0.3 Gy. Under identical conditions, the D0 values for 2-(125)IA and 4-(125)IA were 22.4 +/- 0.6 x 10(11) disintegrations and 4.7 +/- 0.4 x 10(11) disintegrations, respectively. External gamma irradiation and 4-(125)IA produced SSB/DSB ratios of 26.5 +/- 2.1 and 15.9 +/- 2, respectively, while that for 2-(125)IA was 0.6. The average number of DSBs from each decay of (125)I was 0.67 for 2-(125)IA and 0.27 for 4-(125)IA. The results indicate that the decay of (125)I bound to a DNA-intercalating compound produces DSBs 2.5-fold more efficiently than (125)I bound to a nonintercalating compound and support the theoretical expectations that predict a DSB yield that is highly dependent on the proximity of the Auger electron emitter to DNA.

Intrathecal 5-[125I]iodo-2'-deoxyuridine in a rat model of leptomeningeal metastases

The antitumor effect of 5-[125I]iodo-2'-deoxyuridine (125IUdR) was examined in a rat model of leptomeningeal metastases. In this model, 50% of rats develop paralysis of hind limbs. In 9.20 +/- 0.02 days and die in 12.1 +/- 2.1 days after intrathecal (i.t.) implantation of 5 x 10(5) 9L rat gliosarcoma cells.

METHODS

Three days after implantation of 9L gliosarcoma cells, 125IUdR was administered intrathecally to rats as: (a) a single injection (500 microCi/rat), (b) five daily injections (100 microCi/day) or (c) a continuous 5-day infusion (0.5 microliter/hr, total of 500 microCi), and the animals were monitored for the onset of paralysis. Control groups received physiologic saline. For biodistribution studies, rats received a bolus injection of 125IUdR (10 microCi) 5 days after tumor-cell implantation and were killed 1, 8, 24, and 48 hr later. Tissues and organs, including the spinal cord, were isolated and their radioactive content determined. The results were expressed as percent injected dose per gram of wet tissue. Histological sections of the spinal cord were also prepared and used for autoradiographic detection of DNA-incorporated 125IUdR.

RESULTS

Treatment with i.t. administered 125IUdR (500 microCi/rat) significantly (p < or = 0.005) prolonged the median time of paralysis to 11.2 +/- 0.1, 12.3 +/- 0.1 and 15.2 +/- 0.4 days for the single-dose, five daily injections and continuous infusion groups, respectively. Radioactivity cleared rapidly from all tissues except the thyroid and tumor cells growing within the spinal cord. Autoradiography demonstrated that normal cells in the tumor-bearing spinal cord were void of radioactivity.

CONCLUSION

The results suggest that a selective antitumor effect could be achieved in treating leptomeningeal metastases with i.t. administered 125IUdR.

A Weibull regression model with gamma frailties for multivariate survival data

Frequently in the analysis of survival data, survival times within the same group are correlated due to unobserved co-variates. One way these co-variates can be included in the model is as frailties. These frailty random block effects generate dependency between the survival times of the individuals which are conditionally independent given the frailty. Using a conditional proportional hazards model, in conjunction with the frailty, a whole new family of models is introduced. By considering a gamma frailty model, often the issue is to find an appropriate model for the baseline hazard function. In this paper a flexible baseline hazard model based on a correlated prior process is proposed and is compared with a standard Weibull model. Several model diagnostics methods are developed and model comparison is made using recently developed Bayesian model selection criteria. The above methodologies are applied to the McGilchrist and Aisbett (1991) kidney infection data and the analysis is performed using Markov Chain Monte Carlo methods.

The effects of indium-111 decay on pBR322 DNA

We have compared the effectiveness in causing DNA strand breaks of 111In bound to DNA or free in aqueous solution with that of gamma rays. Supercoiled DNA from pBR322 plasmid labeled with [3H]thymidine was purified and mixed with 111InCl3 in the absence or presence of diethylenetriaminepentaacetic dianhydride (DTPA), a metal chelator which prevents the binding of indium to DNA. The reaction mixtures were stored at 4 degrees C to accumulate radiation dose from the decay of 111In. The DNA was then resolved by gel electrophoresis into supercoiled, nicked circular and linear forms, representing undamaged DNA, single-strand breaks (SSBs) and double-strand breaks (DSBs), respectively. The D0 values of pBR322 DNA exposed to gamma radiation from an external 137Cs source and the decay of 111In dispersed in solution (+DTPA) are 3.1 +/- 0.1 and 2.8 +/- 0.1 Gy, respectively. In terms of accumulated 111In disintegrations cm-3 of plasmid DNA solution, the D0 value is 15.3 (+/- 0.7) x 10(10) disintegrations in the absence of DTPA and 38.2 (+/- 1.1) x 10(10) disintegrations in its presence. Since only 14.6 +/- 5% of the 111In was bound to DNA in the absence of DTPA, an effective D0 for bound 111In of 3.4 (+/- 1.1) x 10(10) disintegrations is obtained. The 11-fold (range 9- to 17-fold) increased effectiveness of this Auger electron emitter when in proximity to DNA appears to be due mainly to the higher yield of SSBs.

Quantification of radiation-induced hydroxyl radicals within nucleohistones using a molecular fluorescent probe

We present a method that specifically records .OH formation within histones and possibly at other sites in irradiated nucleohistone. The approach uses the radiation-induced fluorescence emissions from a chromatin-conjugated .OH detector, SECCA (a succinylated derivative of coumarin), that is converted to a fluorescent derivative, 7-hydroxy-SECCA (7-OH-SECCA), after interaction with .OH in neutral aqueous solutions. It is shown that (a) the fluorescent product 7-OH-SECCA cannot be generated by direct radiation effects after gamma or neutron irradiation of SECCA; (b) when SECCA-labeled histone is complexed with DNA to form nucleohistone, the physical properties of the modified nucleohistone are similar to those of unlabeled nucleoprotein; and (c) after irradiation of SECCA-labeled nucleohistone, a linear induction of the fluorescence signal is observed within the radiation doses examined (0.3-30 Gy). Since the sample remains available for further studies after registration of the optical signal, the current approach should permit the investigator to correlate in a single sample the localization and frequency of .OH formation with the results of other assays.

Effect of relative risk and cluster configuration on the power of the one-dimensional scan statistic

The scan test for clustering in time is based on the maximum number of events in an interval (window) of width w as the window moves across the entire time frame. Power estimates of the scan statistic are simulated for a variety of epidemiologically motivated situations. Two cluster configurations are used: a rectangular pulse, and a triangular pulse designed to emulate environmental contamination. For a rectangular pulse, the relative risk R of disease in the cluster region is R-fold as high as it is for the background region. The power is strongly influenced by the sample size, the relative risk, and the width or duration of the cluster region, whereas the effect of the cluster configuration is small. Using a 5 per cent significance level, a relative risk of 4, a standardized cluster duration of 0.10, a relative window width of 1.5, and a (non-random) sample size of 50, the simulated power is approximately 80 per cent, indicating that the minimum sample size in the cluster region for adequate power is in the 12-32 range for values of the parameters used in this study.

A method for detection of hydroxyl radicals in the vicinity of biomolecules using radiation-induced fluorescence of coumarin

A novel method is described to quantitate radiation-induced hydroxyl radicals in the vicinity of biomolecules in aqueous solutions. Coumarin-3-carboxylic acid (CCA) is a non-fluorescent molecule that, upon interaction with radiation in aqueous solution, produces fluorescent products. CCA was derivatized to its succinimidyl ester (SECCA) and coupled to free primary amines of albumin, avidin, histone-H1, polylysine, and an oligonucleotide. When SECCA-biomolecule conjugates were irradiated, the relationship between induced fluorescence and dose was linear in the dose range examined (0.01-10 Gy). The fluorescence excitation spectrum of irradiated SECCA-biomolecule conjugates was very similar to that of 7-hydroxy-SECCA-biomolecule conjugates, indicating the conversion of SECCA to 7-hydroxy-SECCA following irradiation. Control studies in environments that excluded certain radiation-induced water radicals for both the conjugated and unconjugated forms of irradiated SECCA demonstrated that: (1) the induction of fluorescence is mediated by the hydroxyl radical; (2) the presence of oxygen enhances induced fluorescence by a factor of about 1.4, and (3) other primary water radicals and secondary radicals caused by interaction of primary water radicals with biomolecules do not significantly influence the induced fluorescence. The data indicate that the induction of fluorescence on SECCA-biomolecule conjugates records specifically the presence of the hydroxyl radical in the immediate vicinity of the irradiated biomolecule. The method is rapid and sensitive, uses standard instrumentation, and the sample remains available for further studies.

Thermal sensitivity and kinetics of thermotolerance in bovine aortic endothelial cells in culture

The effect of heat on the clonogenicity of bovine aortic endothelial (BAE) cells in vitro was measured. Continuous heating of cells at 43 degrees C or 43.5 degrees C produced survival curves exhibiting thermoresistant tails. When heated at 44 degrees C the survival curve of BAE cells was exponential except for a small shoulder. The BAE cells heated at 44 degrees C and 45 degrees C had D0 values of 33 min and 19 min, respectively. The development of thermotolerance in BAE cells was studied by measuring the sensitivity of cells to a 44 degrees C heating at various times following a priming heat treatment at 43 degrees C or 44 degrees C for 30 min. The thermotolerance ratio in BAE cells preheated at 43 degrees C for 30 min reached a peak of 3.8 at 3 h and declined to 1.9 at 24 h after the prime heating. After prime heating at 44 degrees C for 30 min the thermotolerance ratio increased rapidly to 5.4 in 5 h, remained elevated at 12 h and then declined to a value of 2.1 at 24 h. Thermotolerance in endothelial cells may be partially responsible for the thermotolerance in blood vessels of normal tissues and tumours.

Response of cultured IEC-17 normal rat intestinal epithelial cells to X radiation

The growth parameters and radiosensitivity of normal rat intestinal epithelial cells, IEC-17, were studied. The cells were cultured by standard methods and exposed to an array of doses (1-12 Gy) of 250 kVp X rays. The survival curves generated exhibited no initial shoulder and were bimodal. The Do of the first component was about 0.2 Gy and the second component. 5.0 Gy. The ability of this cell line to repair sublethal lesions was examined by fractionation studies; repair was completed within 60 min after the first dose. When Chinese hamster ovary (CHO) cells were grown under the same conditions used for the IEC-17 cells and then irradiated with single doses, a typical survival curve with a Do of 1.4 Gy was obtained. The survival curves obtained for the IEC-17 cell line are consistent with the response of a morphologically distinct single population containing two functionally separate types of cells.

Induction of 2',3'-cyclic nucleotide 3'-phosphohydrolase and morphological alterations in C6 glioma cells by dexamethasone, (3-butoxy-4-methoxybenzyl)-2-imidazolinone and prostaglandin E1

Dexamethasone, RO20-1724 and prostaglandin E1 all induced morphological alterations and increased the glial specific enzyme 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) in rat C6 glioma cells in culture. Morphological alterations consisted mainly in the development of astrocytelike changes. Increases in dexamethasone-induced CNP activity was time dependent. Dexamethasone reduced cell growth rate, depending on the concentration employed.

Cyclic nucleotides in the regulation of expression of differentiated functions in neuroblastoma cells

Adenosine 3',5'-cyclic monophosphate (cAMP) may be one of the important factors in regulating the expression of many differentiated functions in neuroblastoma cells, but some of these functions can be induced by agents that do not increase the intracellular level of cAMP. An elevation of the intracellular level of guanosine 3',5'-cyclic monophosphate (cGMP) neither induced differentiation nor antagonized the effects of cAMP. Neuroblastoma cells increased the level of cAMP-binding proteins during differentiation, whereas glial cells and L-cells did not. This might have accounted in part for an increase in the intracellular level of cAMP even in the presence of high phosphodiesterase activity in neuroblastoma cells, since the protein-bound with the same proteins, but cAMP had about 10 times higher affinity than did cGMP. cAMP promoted the organization of microtubules and microfilaments necessary for the expression of differentiated phenotypes. The extension of neurites required the synthesis of new protein, but it did not need the synthesis of new RNA. cAMP induced differentiation in neuroblastoma cells by increasing the expression of some genetic information while suppressing the expression of others; e.g., the activities of neural enzymes increased, whereas the synthesis of histone and the phosphorylation of H1-histone markedly decreased in differentiated cells. A hypothesis was offered: An increase in cAMP phosphodiesterase activity as a result of mutation in the regulatory gene for phosphodiesterase in a single, or group of, dividing nerve cell(s) is the primary lesion that leads to malignancy. Based on the concept that selective cytocytoxic drugs should be used with agents that cause differentiation, a new therapeutic approach was suggested for the treatment of neuroblastoma. This involved administration of sodium butyrate followed by L-DOPA or prostaglandin E1 in the presence of cAMP phosphodiesterase inhibitor followed by the less immunosuppressive vincristine and 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide.

Superoxide dismutase activity of normal murine liver, regenerating liver, and H6 hepatoma

By means of both direct assay and gel electrophoresis, normal A/J mouse liver was shown to possess both Cu-Zn and Mn superoxide dismutase (SD) activity. H6 hepatoma cells contained Cu-Zn SD activity, but no Mn SD activity was detectable. Isolated mitochondria from normal liver contained both forms of the enzyme, but isolated mitochondria from H6 hepatoma cells contained no SD activity. To ascertain whether this loss of Mn SD activity was characteristic of these tumor cells or was simply a property of rapidly dividing cells, SD activity was measured in regenerating liver. Mn SD activity was present in the regenerating liver at all times after surgery. Hence loss of the Mn SD activity seemed to be a characteristic of some tumor cells but not of corresponding rapidly dividing normal cells.

Electronmicroscopic identification of type C particles in cultured murine neuroblastoma

Monolayer of murine neuroblastoma were treated with dexamethasone and examined by electronmicroscopy. Most of the treated cells were morphologically differentiated and exhibited type C virus particles which were budding from the cell surface. This in vitro system may be of great value for exploring the oncogenic potential of the virus, and its possible role in cell differentiation.

Morphological differentiation of a murine neuroblastoma clone in monolayer culture induced by dexamethasone

Dexamethasone induces morphological differentiation in murine neuroblastoma cells in culture. The percentage of differentiated cells depends on the concentration of dexamethasone in the medium and duration of treatment. After drug removal (with or without replating), many cells maintain their differentiated phenotype. Dexamethasone-treated cells have larger soma and contain more protein. Dexamethasone also produces a concentration-dependent inhibition of population growth. Growth inhibition is complete by 2 days following treatment with dexamethasone 50 micrograms/ml. Complete growth inhibition is achieved prior to the complete expression of morphological differentiation. Androstenedione, testosterone, and 17-beta-estradiol--all steroids without glucocorticoid activity--have no differentiating effect, although they inhibit growth or cause cell death at higher concentrations.

Superoxide dismutase activity of Ehrlich ascites tumor cells

A crude extract of Ehrlich ascites tumor cell homogenate was found to contain three distinct bands of superoxide dismutase activity by polyacrylamide gel electrophoresis. Activity bands migrated approximately the same distance and were inhibited by cyanide ions. Isolated mitochondria produced two bands of activity that were also inhibited by cyanid. Ethanol-chloroform treatment of the homogenate had no observable effect on these bands of activity, which suggested that the cyanide-insensitive mitochondrial superoxide dismutase activity in these malignant cells was either present in concentrations below detectable levels or completely absent. Normal liver was used as a control for the detection system.

Binding of cyclic nucleotides with proteins in malignant and adenosine cyclic 3':5'-monophosphate-induced "differentiated" neuroblastoma cells in culture

The binding of adenosine cyclic 3':5'-monophosphate (cyclic AMP) with soluble (100,000 X g supernatant), pellet, and total homogenate proteins from cyclic AMP-induced "differentiated" mouse neuroblastoma cells increased by about two-fold. The extent of binding with soluble proteins was higher than that with pellet proteins. The binding of cyclic AMP with soluble proteins from 5'-adenosine monophosphate-treated, serum-free medium-treated, sodium butyrate-treated, 6-thioguanine-treated, or X-irradiated neuroblastoma cells did not significantly change. When the soluble proteins containing bound cyclic [3H]AMP were filtered through a Sephadex G-25 column, the relative amount of protein-bound cyclic [3H]AMP in differentiated cells was greater than that in malignant cells, but the amount of free cyclic [3H]AMP was correspondingly less. The electrophoretic characteristics of cyclic AMP-binding proteins of differentiated and malignant cells were identical. There were two binding peaks, but the extent of binding at each peak was relatively high in differentiated neuroblastoma cells. An increase in cyclic AMP binding occurred 24 hr after treatment of neuroblastoma cells with prostaglandin E1. This increase was completely blocked by cycloheximide but not by actinomycin D. The binding was heat labile and sensitive to protease action. These data indicate that the increase in binding in differentiated cells is due to an elevation in the levels of binding proteins. The binding of cyclic AMP with soluble proteins from rat glial cells and mouse L-cells did not significantly change after treatment with prostaglandin E1 or an inhibitor of cyclic AMP phosphodiesterase. Cyclic AMP and guanosine cyclic 3':5'-monophosphate bind with the same proteins, but cyclic AMP has about 10-fold higher binding affinity than does guanosine cyclic 3':5'-monophosphate.

Effect of neurotransmitters, Guanosine triphosphate, and divalent ions on the regulation of adenylate cyclase activity in malignant and adenosine cyclic 3':5'-monophosphate-induced "differentiated" neuroblastoma cells

The effect of acetylcholine, 3,4-dihydroxyphenylethylamine, prostaglandin (PGE1), guanosine triphosphate (GTP), and divalent ions on adenylate cyclase activity in homogenates of ""differentiated" and malignant mouse neuroblastoma cells was studied. The sensitivity of adenylate cyclase to acetylcholine and 3,4-dihydroxyphenylethylamine markedly increased in adenosine cyclic 3:5-monophosphate-induced differentiated neuroblastoma cells. Although 3,4-dihydroxyphenylethylamine stimulated adenylate cyclase activity in malignant neuroblastoma cells, it failed to do so in X-irradiation induced differentiated cells. PGE1 and GTP stimulated adenylate cyclase activity in malignant and adenosine cyclic 3:5-monophosphate induced differentiated neuroblastoma cells to about the same level. GTP protentiated the PGE1 effect in differentiated concentrations of magnesium and manganese inhibited adenylate cyclase activity; this effect was more pronounced in differentiated cells than in malignant cells. Calcium stimulated adenylate cyclase activity in malignant and differentiated cells to about the same level. There was no significant difference in the values of Km and Vmax of neuroblastoma cells. This study shows that the sensitivity of adenylate cyclase to neurotransmitters and divalent ions (magnesium and manganese) and the sensitivity of PGE1 stimulated enzyme activity to GTP increase in adenosine cyclic 3:5-monophosphate-induced differentiated neuroblastoma cells. Therefore, we suggest that the reverse may be true during malignant transformation of nerve cells.