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Biomedical subjects

Ashok Kumar

Publications and source records attributed to Ashok Kumar.

At least 19 recordsLinked to original sources
PubMed2026

Synthesis of Padina boergesenii-Derived Zinc Oxide Nanoparticles and their Therapeutic Potential Against Oral Squamous Cell Carcinoma: A Transcriptomic and in Vitro Evaluation.

Cancer remains a major health challenge, with oral squamous cell carcinoma (OSCC) being an high aggressive subtype of head and neck squamous cell carcinoma that lacks effective therapeutic options. Current study integrates the synthesis of zinc oxide nanoparticles (ZnO-NPs) from the marine brown algae Padina boergesenii with the OSCC gene expression profile to evaluate their potential therapeutic effects against OSCC. Herein, the ZnO-NPs from Padina boergesenii were prepared through the green synthesis method. The obtained ZnO-NPs were characterized through spectroscopic methods, the UV spectrophotometer shows maximum absorbance at 372 nm, FT-IR presents Zn-O functional band at 516 cm- 1, HR-TEM confirms average particle size of 55.70 nm and the Zetasizer shows zeta potential of + 12.9 mV, indicating colloidal stability. The cytotoxicity assay with ZnO-NPs against oral cancer cell lines exhibited a reduction in cell viability at IC₅₀ value of 20 µg/mL. Meanwhile, the transcriptome analysis of OSCC highlights that MYC, STAT3, BRCA1, and AKT1 are the OSCC therapeutic targets involved in proliferation, immune evasion, genomic instability, and cancer signalling pathways. Further, qRT-PCR based gene expression analysis demonstrates significant down-regulation of these targets upon ZnO-NPs treatment in KB cell lines. Overall, this study emphasizes the anticancer potential of Padina boergesenii-derived ZnO-NPs that could effectively modulate the therapeutic targets and may benefit the treatment of OSCC cancer.

Cytotoxicity↗
PubMed2007

Mechanisms of regulation of CXCR4/SDF-1 (CXCL12)-dependent migration and homing in multiple myeloma.

The mechanisms by which multiple myeloma (MM) cells migrate and home to the bone marrow are not well understood. In this study, we sought to determine the effect of the chemokine SDF-1 (CXCL12) and its receptor CXCR4 on the migration and homing of MM cells. We demonstrated that CXCR4 is differentially expressed at high levels in the peripheral blood and is down-regulated in the bone marrow in response to high levels of SDF-1. SDF-1 induced motility, internalization, and cytoskeletal rearrangement in MM cells evidenced by confocal microscopy. The specific CXCR4 inhibitor AMD3100 and the anti-CXCR4 antibody MAB171 inhibited the migration of MM cells in vitro. CXCR4 knockdown experiments demonstrated that SDF-1-dependent migration was regulated by the P13K and ERK/ MAPK pathways but not by p38 MAPK. In addition, we demonstrated that AMD3100 inhibited the homing of MM cells to the bone marrow niches using in vivo flow cytometry, in vivo confocal microscopy, and whole body bioluminescence imaging. This study, therefore, demonstrates that SDF-1/CXCR4 is a critical regulator of MM homing and that it provides the framework for inhibitors of this pathway to be used in future clinical trials to abrogate MM trafficking.

Animals↗
PubMed2007

IL-10 regulation by HIV-Tat in primary human monocytic cells: involvement of calmodulin/calmodulin-dependent protein kinase-activated p38 MAPK and Sp-1 and CREB-1 transcription factors.

The anti-inflammatory cytokine, IL-10 plays an important role in HIV immunopathogenesis. The HIV accessory protein, Tat is not only critical for viral replication, but affects the host immune system by influencing cytokine production including IL-10. During HIV infection, IL-10 production by monocytic cells is up-regulated, representing a critical pathway by which HIV may induce immunodeficiency. Herein, we show that extracellular Tat-induced IL-10 expression in normal human monocytes. To understand the signaling pathways underlying HIV-Tat induced IL-10 transcription, we investigated the involvement of MAPK as well as calcium signaling and the downstream transcription factor(s). Our results suggest that Tat-induced calcium influx regulated IL-10 transcription in monocytic cells. The experiments designed to further understand the molecules involved in the calcium signaling suggested that calmodulin and calmodulin-dependent protein kinase-II (CaMK-II)-activated p38 MAPK played a role in extracellular Tat-induced IL-10 expression in primary human monocytes. Furthermore, Tat-induced IL-10 expression was regulated by p38 MAPK- and CaMK II-activated CREB-1 as well as Sp-1 transcription factors. Taken together, our results suggest that extracellular HIV-Tat induced IL-10 transcription in primary human monocytes is regulated by CREB-1 and Sp-1 transcription factors through the activation of calmodulin/CaMK-II-dependent p38 MAPK.

Calcium↗
PubMed2006

Environmental enrichment decreases the afterhyperpolarization in senescent rats.

Previous research indicates that an age-related increase in the amplitude of the Ca2+-dependent, K+-mediated afterhyperpolarization (AHP) is related to cognitive decline. However, because the AHP is measured following completion of training, it is unclear whether the AHP amplitude is strictly dependent on biological aging or is modified by the training procedure. To address this distinction we examined the effect of environmental enrichment on the AHP amplitude. Young (5-8 months) and aged (22-24 months) male Fischer 344 rats were exposed to environmental enrichment conditions (EC) or maintained in individual cages (IC). Following 8-10 weeks of differential experience, sharp microelectrode current-clamp recordings were obtained in CA1 pyramidal neurons in hippocampal slices. Examination of the AHP demonstrated that the amplitude was significantly reduced in aged animals exposed to enriched conditions. The results indicate that the amplitude of the AHP in hippocampal pyramidal cells from aged animals is dependent on the history of experience and hippocampal activity.

Action Potentials↗
PubMed2006

Activation of JNK-dependent pathway is required for HIV viral protein R-induced apoptosis in human monocytic cells: involvement of antiapoptotic BCL2 and c-IAP1 genes.

Human immunodeficiency virus (HIV) accessory protein viral protein R (Vpr) plays a key role in virus replication and induces cell cycle arrest and apoptosis in various cell types including T cells and neuronal and tumor cells following infection with Vpr-expressing HIV isolates or exposure to the extracellular Vpr protein. The C-terminal Vpr peptide encompassing amino acids 52-96 (Vpr-(52-96)) is required for exerting the apoptotic effects, whereas the N-terminal Vpr-(1-45) peptide is responsible for virus transcription. We demonstrate that Vpr-(52-96) induced apoptosis in human promonocytic THP-1 cells and primary monocytes through the mitochondrial pathway in a caspase-dependent manner. To understand the regulation of Vpr-induced apoptosis, we investigated the signaling pathways, particularly the MAPKs, and the transcription factors involved. Although both Vpr-(52-96) and Vpr-(1-45) peptides induced phosphorylation of all the three members of the MAPKs, Vpr-(52-96)-activated JNK selectively induced apoptosis in monocytic cells through the mitochondrial pathway as determined by using JNK inhibitors SP60025, dexamethasone, curcumin, and JNK-specific small interfering RNAs. Furthermore Vpr-(52-96)-induced apoptosis was mediated by inhibition of downstream antiapoptotic Bcl2 and c-IAP1 genes whose expression could be restored following pretreatment with JNK-specific inhibitors. Overall the results suggest that Vpr-(52-96)-activated JNK plays a key role in inducing apoptosis through the down-regulation of antiapoptotic Bcl2 and c-IAP1 genes.

Apoptosis↗
PubMed2006

Oxidative stress in neonatal hyperbilirubinemia.

We investigated the role of bilirubin as an antioxidant in neonatal hyperbilirubinemia (NNH) by measuring malondialdehyde (MDA) levels, a marker of oxidative stress and key antioxidant enzymes viz., superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) in otherwise healthy 70 term newborns with NNH and 20 control newborns without jaundice. Jaundiced newborns had significantly lower MDA but higher SOD, catalase and GPx levels. Furthermore, plasma bilirubin showed significant negative correlation with MDA but positive correlation with antioxidant enzyme activities. It is concluded that NNH is associated with lower oxidative stress.

Case-Control Studies↗
PubMed2006

An unusual presentation of a rare chest wall tumour: giant cell tumour of bone.

Giant cell tumour of bone is an aggressive benign bone tumour. It rarely affects the ribs. It usually involves the posterior end of the ribs and literature regarding anterior end involvement is scanty. We report a case of giant cell tumour of the anterior end of the rib masquerading as a sub-mammary abscess in lactating women.

Abscess↗
PubMed2006

Evaluation of protective efficacy of Spirulina fusiformis against mercury induced nephrotoxicity in Swiss albino mice.

The toxicity of mercury to animals and man is well established and this depends greatly on the form of the mercury compounds. In most animals' species, including man, the kidney is the main site of deposition of inorganic mercury and target organ for its toxicity. In the present study Spirulina fusiformis (a cyanobacterium, belongs to family--Oscillatoriaceae) has been investigated as a possible modifier of mercury induced renal damages in Swiss albino mice. Animals were divided into four groups. (i) Control group--only vehicle (0.9% NaCl) was administered as i.p. (ii) HgCl(2) treated group--5.0 mg/kg b.wt. HgCl(2) was administered as i.p. (iii) Spirulina treated group--800 mg/kg b.wt. Spirulina extract was administered orally. (iv) Combination group--S. fusiformis was administered 10 days before mercuric chloride administration and continued upto 30 days after mercuric chloride administration (5.0 mg/kg b.wt.). The animals were autopsied on 1, 3, 7, 15 and 30 days after treatment and the activity of alkaline phosphatase (ALP), acid phosphatase (ACP), lactate dehydrogenase (LDH) and MDA (malondialdehyde) level were measured in kidney homogenates. The results indicated that there was a time-dependent significant enhancement in MDA content and ACP activity and decrease in LDH and ALP activity observed after HgCl(2) treatment. Mercury intoxication also induces pathological alterations in the kidney such as degeneration of glomerulus, proximal and distal tubules. A dose-dependent mortality was also observed following administration of different doses of HgCl(2). In combined treatment of Spirulina with HgCl(2), a significant decrease in MDA content and ACP activity and elevation in LDH and ALP activity was observed as compared to HgCl(2) treated group. Spirulina pre- and post-treatment with mercury also significantly reduces pathological alterations in kidney. Thus, the results from the present study suggest that S. fusiformis can significantly modify the renal damages against mercuric chloride induced toxicity.

Acid Phosphatase↗
PubMed2006

Urokinase separation from cell culture broth of a human kidney cell line.

A single step ion-exchange chromatography on a sulfo-propyl (SP)- Sepharose column was performed to separate both the high molecular weight (HMW)- and low molecular weight (LMW)- forms of enzymatically active urokinase type plasminogen activator from human kidney (HT1080) cell culture media. The level of urokinase secreted by the cell line reached to about 145 Plough units/ml culture broth within 48 h of cultivation. The conditioned cell culture media was applied directly to the column without any prior concentration steps. Polyacrylamide gel electrophoresis of the column eluates in the presence of sodium dodecyl sulphate showed that the cell line secretes three forms of two-chain high molecular weight (HMW) urokinase of molecular weights (M(r)) 64,000, 60,900 and 55,000. In addition, two low molecular weight (LMW) forms of M(r) 22,000 and 20,000; proteolytic cleavage products of HMW, were also found. The HMW and LMW forms had intrinsic plasminogen dependent proteolytic activity as judged by zymographic analysis. The specific activity of the pooled peak fractions increased (approximately 93-fold) to values as high as 1481 Plough units/ mg protein. Both HMW as well as LMW forms were obtained in significantly high yields.

Cell Line↗
PubMed2006

Infectivity rate and transmission potential of Hyalomma anatolicum anatolicum ticks for Babesia equi infection.

The infectivity rate of Babesia equi in the salivary glands of Hyalomma anatolicum anatolicum was assessed. The hungry nymphs were fed on a donkey experimentally infected with B. equi. The engorged dropped-off nymphs were collected at different levels of parasitaemia and kept in BOD incubator. After ecdysis, the hungry adults were prefed on rabbits for different time intervals, thereafter the salivary glands were dissected out and acini were examined after methyl green pyronin (MGP) staining. A total of 134 male and 139 female ticks were dissected out. Average infected acini per tick were found to be significantly higher (p<0.05) in male as compared to the female ticks. Further, maximum infected acini in both male and female ticks were found at 24h of prefeeding on rabbits and overall infected acini per tick increased with rise in parasitaemia. The release of infected ticks on susceptible donkeys resulted in development of clinical babesiosis.

Animals↗
PubMed2006

Modulation of CR1 transcript in systemic lupus erythematosus (SLE) by IFN-gamma and immune complex.

Reduced expression of Erythrocyte Complement Receptor 1 (E-CR1) is envisaged to contribute significantly to the pathophysiology of systemic lupus erythematosus (SLE). We determined the levels of CR1 transcript in the neutrophils from 25 untreated patients with active SLE and 25 normal healthy individuals and, studied the effect of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and immune complexes (IC) on the same. The study revealed a marked decline in the levels of neutrophil CR1 (N-CR1) transcript in the patients with SLE, and differential pattern of IFN-gamma and IL-4 expression in the neutrophils from normals and patients. Opsonized immune complexes down regulated CR1 transcript in patients and IFN-gamma up regulated the same both in normals and patients. Immune complexes suppressed this effect of IFN-gamma. IL-4 also suppressed the effect of IFN-gamma but effect confined only to the normals. This is the first real-time RT-PCR data comparing the neutrophil CR1 expression in normals and patients with SLE and its modulation by IFN-gamma, IL-4 and immune complexes. IFN-gamma and immune complexes, respectively, emerged as the positive and negative modulators of neutrophil CR1 transcript in SLE.

Adult↗
PubMed2006

Intracellular HIV-Tat expression induces IL-10 synthesis by the CREB-1 transcription factor through Ser133 phosphorylation and its regulation by the ERK1/2 MAPK in human monocytic cells.

Human immunodeficiency virus (HIV)-Tat plays an important role in virus replication and in various aspects of host immune responses, including dysregulation of cytokine production. IL-10, an anti-inflammatory cytokine, is up-regulated during the course of HIV infection representing an important pathway by which HIV may induce immunodeficiency. Here we show that extracellular as well as intracellular Tat induced IL-10 expression in normal human monocytes and promonocytic THP-1 cells. The signaling pathways involved in the regulation of IL-10 production by endogenous Tat remain unknown. To understand the molecular mechanism underlying intracellular Tat-induced IL-10 transcription, we employed a retroviral expression system to investigate the role of MAPKs and the transcription factor(s) involved. Our results suggest that an inhibitor specific for the ERK1/2, PD98059, selectively blocked intracellular Tat-induced IL-10 expression in THP-1 cells. Furthermore, intracellular Tat activated the CREB-1 transcription factor through Ser(133) phosphorylation that was regulated by ERK MAPK as determined by IL-10 promoter analysis and gel shift assays. Overall, our results suggest that intracellular HIV-Tat induces IL-10 transcription by ERK MAPK-dependent CREB-1 transcription factor activation through Ser(133) phosphorylation.

Cyclic AMP Response Element-Binding Protein↗
PubMed2006

Characterization and quantitative determination of impurities in piperaquine phosphate by HPLC and LC/MS/MS.

Four impurities in piperaquine phosphate bulk drug substance were detected by a newly developed gradient reverse phase high performance liquid chromatographic (HPLC) method. These impurities were identified by LC/MS/MS. The structures of impurities were confirmed by spectroscopic studies (NMR and IR) conducted using synthesized authentic compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. The system suitability of HPLC analysis established the validity of the separation. The method was validated according to ICH guidelines with respect to specificity, precision, accuracy and linearity. Forced degradation studies were also performed for piperaquine phosphate bulk drug samples to demonstrate the stability indicating power of the newly developed HPLC method.

Chromatography, High Pressure Liquid↗
PubMed2006

Upregulation of human angiotensinogen (AGT) gene transcription by interferon-gamma: involvement of the STAT1-binding motif in the AGT promoter.

Mechanisms to maintain blood pressure in the face of infection are critical to survival. The angiotensinogen (AGT) gene locus is an important component of this response. Thus the AGT gene, expressed predominantly by liver cells, is known to be a positive acute phase reactant. We have previously demonstrated activation of the AGT promoter in hepatocytes through the IL6/STAT3 signaling mechanism. We have now investigated whether IFN-gamma, a cytokine also induced in response to diverse infections, can regulate AGT gene expression, and have elucidated the molecular mechanism involved. IFN gamma treatment up-regulated AGT mRNA level and promoter activity in Hep3B hepatocytes. Sequential deletion of the promoter from the 5' side suggested the major IFN gamma responsive DNA element to be between -303 and -103. This region contained a candidate STAT1-binding site between -271 and -279. EMSA and chromatin immuno-precipitation (ChIP) assays confirmed that IFN-gamma treatment induced the binding of STAT1 to this element. Reporter constructs containing this AGT promoter derived element in a multimerized context but not a mutant version were responsive to IFN gamma. Moreover mutating this STAT1 element in the context of the wild-type AGT holo promoter reduced responsiveness to IFN gamma. In contrast to the clear synergism between dexamethasone and IL 6 in the upregulation of the AGT promoter (through interaction between GR and STAT3), the combination of IFN gamma with IL 6 or with dexamethasone did not further increase AGT promoter activity suggesting that the IFN gamma/STAT1 pathway represents a separate signaling mechanism. These data highlight the redundancy in cytokine-mediated host response pathways aimed at the maintenance of blood pressure during infection.

Angiotensinogen↗
PubMed2006

Increased pro-nerve growth factor and p75 neurotrophin receptor levels in developing hypothyroid rat cerebral cortex are associated with enhanced apoptosis.

Thyroid hormone insufficiency adversely affects cortical development; however, its effect on apoptosis modulation during cerebral cortex development is not understood. We investigated the effect of perinatal hypothyroidism on apoptosis and its mechanisms during rat cerebral cortex development. Primary hypothyroidism was induced by feeding methimazole (0.025% wt/vol) in the drinking water to pregnant and lactating rats and continued until the animals were killed (hypothyroid group). Cerebral cortices from pups were harvested at different postnatal ages (postnatal d 0, 8, 16, and 24 and adult), and apoptosis was quantitated by terminal deoxynucleotide transferase-mediated dUTP nick end labeling and cleaved caspase-3 immunoreactivity. Compared with the euthyroid, primary somatosensory cortex (S1) in the hypothyroid group exhibited enhanced apoptosis. In S1 of euthyroid rats, apoptotic cells were mostly found in cortical layers I-III and the proportion of apoptotic cells enhanced significantly in the hypothyroid group (P < 0.001). Most of the apoptotic cells were neurons, as assessed by double immunolabeling. A significantly increased activation of caspase-3 and -7, decreased levels of antiapoptotic proteins Bcl-2 and Bcl-x(L), and increased levels of proapoptotic protein Bax was observed in the developing cerebral cortex of hypothyroid rats, compared with the euthyroid (P < 0.001). In addition, hypothyroidism significantly elevated the levels of 53-kDa pro-nerve growth factor (P < 0.001) and p75 neurotrophin receptor (P < 0.001) and decreased TrkA expression. Taken together, we provide evidence for the possible contribution of pro-nerve growth factor/p75 neurotrophin receptor pathway in hypothyroidism-enhanced apoptosis during rat cortical development. Thus, the present study may help in explaining the mechanism of the deleterious effect of thyroid hormone deficiency on cerebral cortex development in children.

Animals↗
PubMed2006

Prednisolone in Duchenne muscular dystrophy with imminent loss of ambulation.

An open controlled trial of 0.75 mg/Kg/day prednisolone was conducted at a stage when the patients had started falling several times in a day and stopped on their attaining a chair bound stage, thus minimising the total period of steroid therapy. Out of the 67 DMD patients enrolled in this study, 44 were put on prednisolone therapy and 23 served as controls. All patients were followed-up at two-monthly intervals for two years and thereafter they continued to take their respective medications till their chair-bound stage; then the drug was gradually withdrawn. In the treatment group 24 patients could not continue the trial because of adverse effects - 14 due to excessive obesity, 3 due to measles, 4 due to pulmonary tuberculosis, 2 due to recurrent throat and chest infection and 1 due to an unexplained high leukocyte count. Of the remaining 20 patients in the treatment group, steroid therapy was stopped in 5 patients as there was no improvement in power in six months. Fifteen patients in the treatment group and 19 patients in the control group could be followed regularly for 2 years and then up to chair-bound stage. Outcome parameters included fall frequency, peak expiratory flow rate, limb muscle power, ability to lift weights, time taken in getting up from squatting position, walking 9 metres and climbing 13 stairs. Maximum improvement was noted between 2 and 4 months while mild improvement in some parameters continued up to six months. All parameters remained stabilised for 1 year or so, after which there was slight deterioration. Deterioration at 2 years was, however, less than the natural course of events noted in control patients. Prednisolone treated patients and controls became chair bound at the mean age of 169 +/- 9 and 132 +/- 8 months respectively. Till the ideal stage of the disease and the type or dosage of starting steroid therapy is defined by specially designed studies, 0.75 mg/Kg/day prednisolone therapy may be started in DMD patients at the stage of frequent falls ( > 10 / day) on walking or increased get-up time ( > 10 s) as observed while testing Gowers' sign; this improves muscle power and timing of motor performance within 2-4 months of onset of therapy in about 75% of those who tolerate this therapy, with a possible gain of approximately 3 years in terms of independent walking.

Accidental Falls↗
PubMed2006

Preparative isolation and structural elucidation of impurities in fluconazole by LC/MS/MS.

Three impurities were detected in the LC/MS analysis of fluconazole bulk drug substance. Two of the impurities were unknowns having not been reported previously. Structural assignment of these impurities was carried out by LC/MS/MS using electrospray ionization source and an ion trap mass analyzer. Structural elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by newly developed rapid preparative isolation method. These impurities were characterized as 1-(1-H-1,2,4-triazole-1-yl) propane-2,3-diol and Z-2-(2,4-difluorophenyl)-3-(1-H-1,2,4-triazole-1-yl)-2-propen-1-ol. Their formation and synthesis are discussed.

Chromatography, High Pressure Liquid↗