Electronic and optical properties of CeS under pressure.
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Journal Article↗
Biomedical subjects
S Chatterjee
Publications and source records attributed to S Chatterjee.
Continuous infusion of octreotide in acromegaly.
15 patients with acromegaly were treated with continuous subcutaneous infusion of octreotide in increasing dose from 200 to 1600 micrograms per 24 h by 200 micrograms increments each week. Patients were studied during the initial 7 h of infusion, weekly at each dose level, then after 1 and 2 months at maximum dosage. 13 patients responded well, as judged by growth hormone (GH) suppression and return of insulin-like growth factor 1 to normal, although 1 patient withdrew due to adverse effects; 2 patients showed no significant reduction in GH. In the 12 responders GH level fell within the first 3 h of infusion at a mean plasma octreotide level of 0.76 (SE 0.26) micrograms/l, corresponding to 25 micrograms of infused drug. Optimum suppression of GH occurred at a dosage of 600 micrograms per 24 h, a plasma drug level of 3.5 (0.5) micrograms/l. A definite reduction in tumour size was seen on computerised tomographic scan in 2 patients. All responders noted subjective improvement in acromegalic symptoms. Adverse effects comprised gastrointestinal disturbances, which were transient and mild in 14 patients but severe in 1; biliary sludging occurred in 1 patient. No significant deterioration in carbohydrate tolerance was seen in the responders.
Acromegaly↗
Neutral sphingomyelinase from human urine. Purification and preparation of monospecific antibodies.
A neutral sphingomyelinase which cleaves phosphorylcholine from sphingomyelin at a pH optima of 7.4 was purified 440-fold to apparent homogeneity from normal human urine concentrate employing Sephadex G-75 column chromatography, preparative isoelectric focusing, and sphingosylphospholcholine CH-Sepharose column chromatography. The enzyme is composed of a single polypeptide whose apparent molecular weight is 92,000. Analytical isoelectric focusing revealed that the pI of this enzyme is 6.5. Purified neutral sphingomyelinase was devoid of beta-galactosidase and beta-N-acetylglucosaminidase activity originally present in the urine concentrate. The purified neutral sphingomyelinase (N-SMase) had low levels of phospholipase A1 and A2 activity when phosphatidylcholine was used as a substrate and detergents were included in the assay mixture. However, it had no phospholipase activity toward phosphatidylglycerol and sphingomyelin at pH 4.5 irrespective of the presence or absence of detergents. Monospecific polyclonal antibodies raised against N-SMase immunoprecipitated approximately 70% of N-SMase activity from urine, human kidney proximal tubular cells, and partially purified membrane-bound N-SMase from these cells. Western immunoblot assays revealed that the monospecific polyclonal antibody against urinary N-SMase recognized both the urinary N-SMase and the membrane-bound N-SMase. Because this enzyme is distinct biochemically and immunologically as compared to acid sphingomyelinase (EC 3.1.4.12), we would like to assign it an enzyme catalog number of EC 3.1.4.13. The availability of N-SMase and corresponding antibody will be useful in studying various aspects of this enzyme in biological systems.
Acetylglucosaminidase↗
Topoisomerase II-dependent and -independent mechanisms of etoposide resistance in Chinese hamster cell lines.
Resistance to etoposide (VP-16), amsacrine (mAMSA), and doxorubicin (Adriamycin) was studied in two Chinese hamster cell lines primarily selected for resistance to the epipodophyllotoxin. Both lines demonstrated profound resistance to VP-16, and mAMSA stimulated DNA breakage. However, the resistance to mAMSA cytotoxicity in both lines was less than expected from the level of resistance to the effects of topoisomerase II inhibition. Similarly, resistance to the cytotoxicity of high VP-16 concentrations in one of the lines was less than expected from the resistance to inhibition of topoisomerase II. An analysis of the relation of DNA breaks to drug cytotoxicity suggests that cross-resistance to mAMSA was mainly conferred through loss of mAMSA-stimulated, topoisomerase II-mediated DNA breaks. This mechanism also contributed towards reduced VP-16 cytotoxicity. However, our studies suggest that additional mechanisms, independent of resistance to VP-16-mediated topoisomerase II effects, greatly increased the resistance to this agent. Resistance to VP-16 cytotoxicity, not dependent on resistance to drug-mediated DNA cleavage, could be overcome at high drug concentrations in one of the resistant lines and might be responsible for the greater relative resistance to VP-16 than to mAMSA. These findings suggest the presence of two distinct mechanisms of resistance to VP-16 cytotoxicity, one presumably mediated by topoisomerase II and dependent on resistance to drug-mediated DNA scission, and a second mechanism independent of the effects of the drug on topoisomerase II.
Amsacrine↗
Simultaneous triple-immunogold staining of virus and host cell antigens with monoclonal antibodies of virus and host cell antigens in ultrathin cryosections.
The mechanism of intracellular maturation and sorting of herpes simplex virus type I glycoproteins is not known in details. To elucidate the intracellular sorting of viral glycoproteins and their possible interaction with the cytoskeleton, a method for simultaneous immunogold staining of three antigens in ultrathin cryosections is described. Each antigen is stained by an indirect technique using mouse monoclonal IgG as first layer, rabbit anti-mouse IgG as second and gold-conjugated goat anti-rabbit IgG as third layer antibody. After each staining cycle the sections are covered by methyl cellulose and exposed to paraformaldehyde vapour at 80 degrees C for 30 min. This destroys the free antigen combining sites of the second and the third layer IgG and abolish contaminating staining. Simultaneous triple-staining is documented with three mouse monoclonal antisera specific for 1) herpes simplex virus type 1 glycoprotein C, 2) glycoprotein D and 3) alpha- and beta-tubulin as primary antibodies. Labelling for virus glycoproteins was found in some Golgi vesicles and close to the cytoplasmic microtubules as well as on the cell surface and on intracytoplasmic and extracellular virus particles.
Animals↗
Mutant cells defective in poly(ADP-ribose) synthesis due to stable alterations in enzyme activity or substrate availability.
We used two different approaches to develop cell lines deficient in poly(ADP-ribose) synthesis to help determine the role of this reaction in cellular functions. One approach to this problem was to develop cell lines deficient in enzyme activity; the other approach was to develop cell lines capable of growing with such low nicotinamide adenine dinucleotide (NAD) levels so as to effectively limit substrate availability for poly(ADP-ribose) synthesis. The selection strategy for obtaining cells deficient in activity of poly(ADP-ribose) polymerase was based on the ability of this enzyme to deplete cellular NAD in response to high levels of DNA damage. Using this approach, we first obtained cell lines having 37-82% enzyme activity compared to their parental cells. We now report the development and characterization of two cell lines which were obtained from cells having 37% enzyme activity by two additional rounds of further mutagenization and selection procedures. These new cell lines contain 5-11% enzyme activity compared to the parental V79 cells. In pursuit of the second strategy, to obtain cells which limit poly(ADP-ribose) synthesis by substrate restriction, we have now isolated spontaneous mutants from V79 cells which can grow stably in the absence of free nicotinamide or any of its analogs. These cell lines maintain NAD levels in the range of 1.5-3% of that found in their parental V79 cells grown in complete medium. The pathway of NAD biosynthesis in these NAD-deficient cells is not yet known. Further characterization of these lines showed that under conditions that restricted poly(ADP-ribose) synthesis, they all had prolonged doubling times and increased frequencies of sister chromatid exchanges.
Animals↗
Effect of recombinant hybrid human interferon on replication and morphogenesis of HSV-1 in monkey cells.
Human recombinant alpha interferon, A/D, significantly reduced the replication and cell fusion induced by herpes simplex virus type 1 in monkey cells. Thin-section electron microscopy of interferon-treated monkey cells showed distinct assembly of nucleocapsids within the nucleus. Analysis of virus-specific proteins by the immunoblot technique confirmed that A/D interferon had no significant effect on the expression of major nucleocapsid proteins, although the expression of glycoproteins B and D was reduced in interferon-treated cells. The possibility of an interferon-induced block at a late stage in virus morphogenesis is discussed.
Animals↗
Sequences near the termini are required for transposition of the maize transposon Ac in transgenic tobacco plants.
Deletion derivatives of the maize transposable element Activator (Ac) were constructed in vitro and inserted into a kanamycin resistance gene. These constructions were then introduced into tobacco protoplasts derived from plants previously transformed with Ac. The ability of each deletion derivative to excise was measured by whether or not kanamycin-resistant tobacco calli were recovered. This allowed us to determine the length of DNA present at each terminus that is required to respond to the products expressed by the Ac element present in the genome. We show that around 200 base pairs (bp) are required at both ends for excision to occur at wild-type levels. When between 100 and 200 bp were retained at one of the ends, reduced frequencies of excision were detected. With less than 100 bp remaining at either end, no excision was detected. In addition, we show that although similar lengths of DNA are required at each terminus, the termini are not interchangeable. The significance of these data is discussed with respect to the protein(s) which interact(s) with the termini of Ac.
Blotting, Southern↗
A role for herpes simplex virus type 1 glycoprotein E in induction of cell fusion.
The role of herpes simplex virus type 1 (HSV-1) glycoprotein E (gE) in the induction of multinucleate cell (syncytium) formation was investigated using monoclonal antibodies and a gE deletion mutant, R7023. We found that monoclonal antibodies directed against gE blocked HSV-1-induced syncytium formation in human cells. R7023 also failed to induce syncytium formation in tissue culture cells. The results indicate that gE, in addition to glycoproteins B, D, H and the gene sequence located between 0.732 and 0.745 map units, is involved in cell fusion. Thus, this important biological property appears to be regulated by several HSV-1 gene products.
Animals↗
Effects of melatonin on the growth of MtT/F4 anterior pituitary tumor: evidence for inhibition of tumor growth dependent upon the time of administration.
In the present report, we have examined the anti-tumor potential of melatonin by utilizing the MtT/F4 anterior pituitary transplantable tumor. The tumor was obtained (Bogden Labs.) in cryopreserved condition and transplanted (in the left rear thigh), and allowed to grow for 8 weeks in adult Fischer 344 rats, maintained under uniform laboratory conditions of light (LD 14:10; lights on at 06:00 h), and temperature (21-23 degrees C). Subsequently, the tumor was dissected out, minced, and washed in Medium 199, and similarly transplanted into groups of adult Fischer 344 rats representing the final tumor recipient groups utilized for the evaluation of melatonin's anti-tumor effects. Melatonin (50 micrograms/0.1 ml/animal) was administered subcutaneously either early in the morning (at 08:00 h), or late in the afternoon (at 18:00 h), for 6 weeks, beginning the day after tumor transplantation. The matched controls were given equal volumes of physiological saline. A careful record of the appearance and growth of the tumor was maintained by examining the animals every morning. At the termination of the experimental schedule, the tumor masses were carefully dissected out, rinsed with normal saline, dried, and weighted on a sensitive Mettler balance. Our results showed that melatonin significantly increased the latency period of the tumor, irrespective of the time of drug administration. Analysis of the final tumor weights showed that afternoon, but not morning, injections of melatonin significantly reduced both the absolute (P less than 0.025) and relative (P less than 0.05) tumor weights in comparison to the saline-injected matched control. These results suggest that a) melatonin exhibits its anti-tumor efficacy on MtT/F4 tumor, by delaying the appearance of the tumor, and b) the anti-tumor potential of melatonin is greatly dependent on the time of administration of the drug within the daily light-dark cycle.
Animals↗
Chronic effect of smoking on the electrocardiogram.
The electrocardiograms (ECG) of 232 male non-smokers and 224 male smokers, aged 20-60 years, devoid of cardiovascular diseases, were studied. Among these subjects 5.2% of non-smokers and 6.7% of smokers had pathological ECGs. Non-pathological ECGs of 220 non-smokers and 209 smokers were analyzed for R, S and T-wave amplitudes, P and QRS axes and P-R, QRS and Q-Tc intervals. The 2 groups did not differ significantly from each other for R and T-wave amplitudes in any of the age groups except for 40-60 years, in which R-amplitude obtained from standard limb leads was significantly lower in smokers. S-amplitude recorded from standard limb leads was significantly lower in smokers of all ages combined. The reverse phenomenon was noted for S-amplitude obtained from precordial leads. R, S and T-amplitudes decreased with the advancement of age at a relatively higher rate in smokers. These waves had significant negative correlation with pack years of smoking habit. QRS and P axes differed significantly between smokers and non-smokers. The rate of shifting of these axes to the left with increasing age was relatively higher in non-smokers. Lung function did not show any relation to electrocardiogram in normal healthy subjects. These results indicate that aging affects electrocardiographic wave patterns and that this aging effect is modified by long term smoking.
Adult↗
Camptothecin hypersensitivity in poly(adenosine diphosphate-ribose) polymerase-deficient cell lines.
Mutant cell lines, derived from the Chinese hamster V79 cell line, deficient in poly(adenosine diphosphate-ribose) polymerase activity, and previously shown to be resistant to topoisomerase II inhibitors, were found to be hypersensitive to camptothecin, a topoisomerase I inhibitor. In all the cell lines, camptothecin induced dose-dependent protein-associated DNA single-strand breaks and sister chromatid exchanges. The increased sensitivity to camptothecin-induced cytotoxicity was not associated with an increase in DNA single strand breaks or sister chromatid exchanges. These results suggest the absence of any direct causal relation between (1) camptothecin induced sister chromatid exchanges and cytotoxicity or (2) camptothecin induced DNA strand breaks and cytotoxicity. The hypersensitivity of these mutant cell lines to camptothecin suggests that poly(adenosine diphosphate-ribose) polymerase is involved with topoisomerase I in modulating camptothecin induced cytotoxicity.
Animals↗
Immunomodulatory role of thyroid hormones: effect on humoral immune response to Salmonella typhi O antigen.
Effect of long term administration of thyroid hormones and the removal of thyroid on humoral antibody response to S. typhi O antigen was studied in male albino rats of HM strain. Humoral antibody response to S. typhi O antigen was enhanced in animals pretreated with T3 or T4 at a dose of 10 micrograms daily for 15 days. Administration of thyroid hormones simultaneously along with antigen, resulted in suppression of antibody response. In thyroidectomized animals, the antibody titer to S. typhi O antigen was decreased; this decrease in antibody titer was restored to normal level following hormone supplementation. Thyroidectomy significantly depressed TLC as well. Total leucocyte count and absolute lymphocyte count were increased following hormone treatment. Present findings, thus show the lymphoproliferative response of thyroid hormones and their effect on antibody response suggesting the immunomodulatory role of thyroid hormones.
Animals↗
Effect of thyroid hormones on delayed type hypersensitivity reaction.
The effect of long term administration of thyroid hormones and its deprivation on delayed type hypersensitivity (DTH) reaction to 2-4 dinitrochlorobenzene (DNCB) was studied. Animals were either pre-treated with thyroid hormones (T3 or T4) for 15 days and then subjected to DNCB skin test or the animals received thyroid hormones and simultaneously subjected to DNCB skin test. In both the cases DTH reaction was found to be increased significantly. When DNCB skin test was performed in the thyroidectomized animals, DNCB skin reaction was significantly decreased and the reaction was restored to normal following supplementation of thyroid hormones to the thyroidectomized animals. TLC and ALC were increased significantly following hormone treatment and thyroidectomized animals. TLC hand, induced significant depression in the count which was restored by hormone administration to the thyroidectomized animals.
Animals↗
Regulation of glycosphingolipid glycosyltransferase by low density lipoprotein receptors in cultured human proximal tubular cells.
We have shown previously that low density lipoproteins (LDL) suppressed the synthesis of lactosylceramide in normal human proximal tubular cells, but stimulated such synthesis in proximal tubular cells from LDL receptor negative subjects (Chatterjee, S., Clarke, K., and Kwiterovich, P.O., Jr. (1986) J. Biol. Chem. 261, 13474-13479). To understand the mechanism(s) of this effect of LDL, we have studied here the effects of LDL on the activity of UDP-GalCer:beta-galactosyltransferase (GalT-2). Maximum suppression (70-80%) of the activity of GalT-2 in normal proximal tubular cells at 37 degrees C occurred at a LDL concentration of 25 micrograms/ml medium. Such suppression was not observed either when the cells were incubated with LDL at 4 degrees C, or when the cells were preincubated with leupeptin, followed by incubation with LDL at 37 degrees C. High density lipoproteins and fetuin did not suppress the activity of GalT-2 in normal proximal tubular cells. In contrast LDL modified by reductive methylation (M-LDL, 100 micrograms/ml) stimulated the activity of GalT-2, approximately 3-fold. The effects of LDL and M-LDL were not related to their glycosphingolipid content. Much less suppression and stimulation of the activity of GalT-2 in proximal tubular cells by LDL and M-LDL, respectively, was found in normal human skin fibroblasts, Chinese hamster ovary cells, and bovine smooth muscle cells, suggesting that the LDL-mediated effect may be tissue-specific. In cells grown to very high density, the activity of the LDL receptor is decreased, and there was less suppression of GalT-2 activity by LDL. In normal proximal tubular cells, LDL stimulated the activity of UDP-Gal:LacCer, alpha-galactosyltransferase activity, UDP-Gal:LcOse3Cer, beta-galactosyltransferase, and CMP-NeuAc:LacCer,alpha-sialyltransferase activity but did not alter the activity of sulfotransferase. In conclusion, LDL that entered the normal proximal tubular cells via the LDL receptor-mediated pathway decreased GalT-2 activity, an effect that was dependent upon the binding, internalization, and degradation of receptor-bound LDL. In contrast LDL that entered normal or LDL receptor-negative proximal tubular cells via an LDL receptor-independent pathway failed to suppress GalT-2 activity, and led to a stimulation of LacCer synthesis.
Cell Count↗
Morphological and biochemical effects of gentamicin and cyclosporin-A on urinary cell phospholipids and phospholipases in man.
The morphology, lipid composition, and activity of sphingomyelinase (E.C. 3.1.4.12) and phospholipases A (E.C. 3.1.1.32) and C (E.C. 3.1.4.3) were studied in the urinary cells from four normal subjects, four patients receiving gentamicin (G), and four patients receiving cyclosporin-A (CsA). We report that abnormal urinary excretion of proximal tubular cells occurred in patients receiving G and CsA. Membrane-enclosed sudanophilic material and numerous vacuoles were found in the cytoplasm of the proximal tubular cells from both patients receiving G and those receiving CsA. Patients receiving G shed higher levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and sphingomyelin (SM) in the order of 78%, 38%, and 30% relative to normal. In contrast, the excretions of phosphatidylinositol (PI) and PC were 50% and 30% lower, respectively, in patients receiving CsA as compared to control. Sphingomyelin levels, however, were moderately elevated in these patients' urinary renal tubular cells. The activity of acid sphingomyelinase was one half the normal level in the cells of patients receiving G and CsA. The most striking result was a tenfold decrease in the activity of neutral sphingomyelinase in patients receiving G. In contrast, the activity of neutral sphingomyelinase in patients receiving CsA was similar to control. Phospholipase A activity was decreased and increased 35% and 15%, respectively, in urinary proximal tubular cells from patients receiving G and CsA. We conclude that deficient neutral sphingomyelinase activity precedes phospholipid (PL) overloading and gross pathological changes in patients receiving gentamicin but not in patients receiving cyclosporin-A.
Adult↗
Selection for high and low mating propensity in Drosophila ananassae.
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Animals↗