Biomedical subjects

N K Jain

Publications and source records attributed to N K Jain.

At least 55 records · Page 3Linked to original sources

PubMed2000

High-entrapment liposomes for 6-Mercaptopurine--a prodrug approach.

Low entrapment of drugs into liposomes is a serious challenge in their commercial application. 6-Mercaptopurine (6-MP), an antineoplastic agent, is such a drug with low entrapment efficiency (EE). We devised their lipophilic derivatization as a means of enhancing EE by covalently coupling 6-MP with glyceryl monostearate (GMS) via a succinic anhydride spacer. This prodrug had an improved partition coefficient value of 25.16 compared to 1.22 for free drug, confirming higher lipophilicity. A hydrolysis rate study of prodrug indicated 2.90%, 12.5%, 24.1%, and 25.1% hydrolysis in phosphate buffered saline (PBS) (pH 7.4) and 10%, 20%, and 30% serum, respectively. Liposomes of phosphatidylcholine (PC)/sphingomyelin, cholesterol, and dicetyl phosphate bearing drug or prodrug were prepared by shaking by hand and sonication methods. The EE was found to increase from 1.92% for free drug to 91.8% for drug-conjugate. An in vitro cell line toxicity study on L1210 leukemia cells showed improved performance of liposome-encapsulated drug-conjugate compared to free drug. The plasma drug level profile following administration of free drug and the liposomal formulation containing prodrug (HE liposome) manifested a higher sustained level of the latter, which was further improved in case of sphingomyelin-containing liposomes (STHE liposome). The pharmacokinetic parameters revealed an increase in half-life, from 61 min to 120 min for the HE liposomes and 296 min for the STHE liposomes. Therefore, increased entrapment was made possible through lipophilic derivatization, and it was subsequently tested in vivo.

Animals↗

PubMed2000

Comparison of in house polymerase chain reaction with conventional techniques for the detection of Mycobacterium tuberculosis DNA in granulomatous lymphadenopathy.

AIMS: To evaluate the usefulness of the devR based polymerase chain reaction (PCR) in the detection of Mycobacterium tuberculosis in lymph node aspirates and tissues of lymphadenitis and to compare PCR with conventional diagnostic techniques. SUBJECTS AND METHODS: Coded specimens of fine needle aspirates and biopsies from 22 patients with tuberculous lymphadenitis, 14 patients with non-tubercular lymphadenitis, and nine patients with granulomatous lymphadenitis were processed and subjected to analysis by PCR, smear microscopy, M tuberculosis culture, histology, and cytology. RESULTS: Tuberculous lymphadenitis was correctly diagnosed by PCR in 18 patients, by culture in five patients, by histology in 13 patients, and by cytology in seven patients. PCR gave two false positive results in 14 patients with non-tubercular lymphadenitis. The sensitivity of the conventional techniques was significantly higher with biopsies (17 of 22 specimens; 77%) than with fine needle aspirates (nine of 22 specimens; 41%). However, the sensitivity of PCR was not significantly higher with biopsies (68%) in comparison with fine needle aspirates (55%). The sensitivity of either biopsy PCR or fine needle aspirate PCR was not significantly different from that of either histology combined with culture or cytology combined with culture. The overall combined specificity of PCR was 86%. Mycobacterium tuberculosis DNA was detected in six of nine patients with granulomatous lymphadenitis. CONCLUSION: PCR is the most sensitive single technique available to date for the demonstration of M tuberculosis in specimens derived from patients with a clinical suspicion of tuberculous lymphadenitis. The value of PCR lies in its use as an adjunct test in the diagnosis of tuberculous lymphadenitis, particularly in those patients where conventional methods fail. Because fine needle aspiration is not an invasive procedure, it is the procedure of choice, and PCR should be performed initially on these samples. Excisional biopsy histology and PCR should be recommended only for patients in whom fine needle aspirate PCR is negative or when there is discrepancy with the clinical impression.

Biopsy↗

PubMed2000

Cyclooxygenase isoenzymes and newer therapeutic potential for selective COX-2 inhibitors.

Cyclooxygenase (COX), also known as prostaglandin G/H synthase, is a membrane-bound enzyme responsible for the oxidation of arachidonic acid to prostaglandins that was first identified over 20 years ago. In the past decade, however, more progress has been made in understanding the role of cyclooxygenase enzymes in various pathophysiological conditions. Two cyclooxygenase isoforms have been identified and are referred to as COX-1 and COX-2. COX-1 enzyme is constitutively expressed and regulates a number of housekeeping functions such as vascular hemostasis and gastroprotection, whereas COX-2 is inducible (i.e., sites of inflammation) by number of mediators such as growth factors, cytokines and endotoxins. Nonsteroidal antiinflammatory drugs (NSAIDs) produce their therapeutic effects through inhibition of COX, the enzyme that makes prostaglandins. Nonselective inhibition of COX isoenzyme leads to not only beneficial therapeutic effects but also a number of detrimental effects. Beneficial effects are due to inhibition of COX-2 and detrimental effects are due to inhibition of physiological COX-1. The present review discusses the biology as well as the role of these COX isoenzymes in various pathophysiological conditions.

Animals↗

PubMed2000

Surface modified methotrexate loaded erythrocytes for enhanced macrophage uptake.

The unique property of macrophages to distinguish between 'mature self' and 'senescent self' was applied for the enhanced macrophage uptake upon loading drugs into erythrocytes and provoking environment within which it gets translated into senescent cells. Two different approaches were applied one by depleting the sialic acid from the surface of cells and another by inducing hemichrome formation in the cells. Erythrocytes encapsulation of methotrexate was carried out by preswell dilution technique. Surface modification of erythrocytes was performed using desialation and hemichrome induction by treating with trypsin (Tt) and phenylhydrazine (PhT) respectively. Desialation technique was optimized in terms of concentration of trypsin, incubation temperature and time period. Both of these surface modified erythrocytes were characterized for in vitro macrophage uptake. In vivo organ localization was assessed by recording amount of drug present in different organs. The macrophage uptake of both surface modified erythrocytes was enhanced by almost 3-5 and 5-6 times with Tt and PhT cells, respectively. These new surface modified carriers are found to be excellent candidate for enhanced macrophage uptake and anticipated to be useful for any RES tumors.

Animals↗

PubMed2000

Analgesic and anti-inflammatory effects of phosphodiesterase inhibitors.

The aim of the present study was to investigate the role of phosphodiesterase (PDE) enzyme inhibitors namely rolipram and theophylline in pain and inflammation in experimental animals. Rolipram, a selective PDE IV inhibitor and theophylline a nonspecific PDE inhibitor exerted dose dependent analgesic and anti-inflammatory effect against acetic acid-induced writhing in mice and carrageenan-induced paw edema in rats, respectively. Nimesulide (1, 2 mg/kg) produced significant anti-inflammatory effect. Further, nimesulide (0.5 mg/kg) potentiated analgesic effect of rolipram but it failed to modulate the anti-inflammatory effect of PDE inhibitors. Present study suggests that PDE enzymes might be playing a role in nociceptive and inflammatory responses in animals.

Abdominal Pain↗

PubMed2000

Comparative study of visceral and parietal pleural biopsy in the etiological diagnosis of pleural diseases.

OBJECTIVE: The present study was planned to evaluate the efficacy and diagnostic reliability of conoctional parietal pleural biopsy to a technique of visceral pleural biopsy. METHOD: Study comprises of 54 diagnosed cases of pleural effusion and after establishing the clinical diagnosis for probable etiological causes. Then parietal pleural biopsy using absents punch biopsy needle and vesceral pleural biopsy using Prabhudesai et al technique was taken in all these patients. Size of the tissue yield; percentage of biopsies; diagnostic yield and sensitivity for these two techniques were compared. RESULTS: A definitive etiological diagnosis could be reached in 52 out of 54 patients on the basis of pleural biopsy (33 tuberculous, 16 malignant and 3 pyogenic), 23 (69.7%) tuberculous effusion patients were diagnosis by visceral pleural biopsy and 14 (42.4%) by parietal pleural biopsy out of 33 diagnosed tuberculous effusion cases. While for the 16 malignant effusions the visceral pleural biopsy showed suggestive histological change in 13 (81.25%) patients and the parietal pleural biopsy in seven (43.8%) with five (31.25%) of these patients being positive by both. All three pyogenic effusions showed only nonspecific inflammatory change in both pleurae. CONCLUSION: The mean size of biopsy sample obtained with modified Prabhudesai et al technique was significantly larger than that of the parietal pleural biopsy with Abrams punch (4.85 mm2 V/s 2.5 mm2 with P < 0.01). Adequate pleural tissue was identifiable in 94.4% and 90.7% of cases, respectively. The modified Prabhudesai et al technique proved to be effective safe and easily learnt. Visceral pleural sampling using this technique is a definite superior addition to the present diagnostic armamentarium of an idiopathic pleural effusion and its routine application together with parietal pleural biopsy will help to establish a definitive diagnosis in majority of patients with idiopathic pleural effusions.

Adolescent↗

PubMed1999

Antinociceptive and anti-inflammatory effects of Tanacetum parthenium L. extract in mice and rats.

Oral administration of the feverfew (Tanacetum parthenium) extract led to significant antinociceptive and anti-inflammatory effects against acetic acid-induced writhing in mice and carrageenan-induced paw edema in rats, respectively. These responses were dose-dependent (10, 20, 40 mg/kg, p.o.). Parthenolide (1, 2 mg/kg i.p.), the active constituent of the extract also produced antinociceptive and anti-inflammatory effects. Naloxone (1 mg/kg i.p.), an opiate antagonist, failed to reverse feverfew extract and parthenolide-induced antinociception. Feverfew extract in higher doses (40, 60 mg/kg p.o.) neither altered the locomotor activity nor potentiated the pentobarbitone-induced sleep time in mice. It also did not change the rectal temperature in rats. Feverfew extract exerted antinociceptive and anti-inflammatory effects without altering the normal behaviour of the animals.

Acetic Acid↗

PubMed1999

Lipid grafts of egg-box complex: a new supramolecular biovector for 5-fluorouracil delivery.

An attempt was made to improve the pharmacokinetic behaviour of 5-fluorouracil (5-FU) by incorporating it into lipoprotein imitating synthetic carrier 'supramolecular biovector (SMBV)' which is an important prerequisite for achieving its better therapeutic performance against cancer. The polysaccharide core of SMBVs was prepared by ionotropic gelation technique by cross-linking polyguluronate units in the alginate molecules with calcium ions to form so called 'egg-box structure'. The formulation and process variables were optimized to obtain particles of nanometer size range. Hydrophobization was carried out by fatty-acylation on the surface followed by phospholipid coating. Palmitoyl polyethylene glycol (p-PEG) was anchored to impart stealth behaviour. The scanning electron microscopy showed discrete spheres of average diameter 748 nm. Polydispersity was estimated to be 0.37. Overall zeta potential was -21.3 mV. The drug loading capacity and encapsulation efficiency was found to be 10.0% and 97.9%, respectively. The release from drug solution (AP) followed zero-order kinetics. Higuchi release pattern was obtained for egg-box complex cores (AP1) while first-order pattern was followed for fatty acylated (AP2) and lipid coated cores before (AP3) and after p-PEG anchoring (AP4). The amount of drug liberated in 24 h was in the order AP > AP1 > AP2 > AP4 > AP3. The release pattern obtained was a combined effect of drug diffusion through egg-box matrix as well as partitioning in hydrophobic layer and p-PEG layer around the SMBV. The stability study showed negligible leakage and no appreciable change in particle size upon storage at different temperatures which is an indication of good stability of SMBV formulation. The plasma clearance data revealed increase in circulation half-life of drug and bioavailability. Tissue distribution data obtained was a result of competitive uptake of formulations from tissue macrophages and lymphatics depending upon its surface characteristics and residence period in vascular system. The enhanced delivery of drug to lymphatics and improvement in its half-life render SMBVs useful for control of metastasis and tumour growth.

Alginates↗

PubMed1999

Lipoprotein-mimicking biovectorized systems for methotrexate delivery.

The present investigation reports a new family of lipid nanoparticles biomimetic of lipoproteins, lipoprotein-mimicking biovectorized systems (LMBVs), for the delivery of methotrexate. LMBVs were prepared by microemulsion congealing technique, and the composition and process were optimized. The palmitoylpolyethylene glycol 4000 (p-PEG 4000) was anchored on LMBVs as apoprotein analogue. Various formulations were prepared and characterized for size and polydispersity, zeta potential, drug entrapment efficiency, anchoring efficiency, release kinetics, pharmacokinetics and tissue distribution. The size was 70-76 nm and the polydispersity was 0.09-0.18. The zeta potential was -63.2 which was reduced to -19.3 after p-PEG 4000 coating. Entrapment efficiency varied from 22.6% to 30.2%. Anchoring efficiency was 74.0 +/- 3.9%. The drug release showed zero-order profile. Their circulation half-life was enhanced and exhibited capability to accumulate in tissues for longer periods. The composition of lipidic part of LMBVs and p-PEG 4000 anchoring impart similarity with natural lipoproteins in terms of in vivo behaviour. This new drug carrier named LMBVs, holds promise for targeting and systemic controlled release, which may prove effective in the treatment of various types of cancer.

Animals↗

PubMed1999

L-NAME, a nitric oxide synthase inhibitor, modulates cholinergic antinociception.

Systemic administration of sumatriptan and buspirone (20 mg/kg: 5-HT1A agonists) produced antinociception against acetic acid-induced writhing. The antinociceptive effect was potentiated by cholinomimetic physostigmine (0.05 mg/kg i.p.) and blocked by the muscarinic antagonist atropine (5 mg/kg i.p.). Naloxone, an opiate antagonist, failed to reverse the sumatriptan- or buspirone-induced antinociception, but pindolol (10 mg/kg), a nonselective 5-HT1A antagonist, blocked this response. Sumatriptan- or buspirone-induced antinociception was significantly potentiated by L-NAME (a nitric oxide [NO] synthase inhibitor) although L-NAME (20 mg/kg) given alone had no effect on the nociceptive threshold. Recent studies have suggested that the L-arginine/NO/cGMP pathway is involved in the modulation of pain perception. The present results suggest that NO may play a role in cholinergic antinociception-mediated 5-HT1A receptor stimulation and that NO exerts an inhibitory action on cholinergic analgesia.

Acetic Acid↗

PubMed1999

Multiple emulsions containing rifampicin.

A stable multiple emulsion containing rifampicin in the internal aqueous phase was prepared by the incorporation of additives in both aqueous and oily phases. The formulation and process variables were optimized for primary and secondary emulsification. Drug release studies were performed on selected multiple emulsions to observe the effect of dilution. The release data were fitted to the Higuchi equation for slab and spherical geometry and effective diffusion coefficients were calculated. Stability studies for three months revealed good stability of the multiple emulsions with respect to creaming, phase separation, viscosity change, drug leakage, change in droplet size upon storage and exposure to osmotic and shear stress. The in vivo studies performed with stable multiple emulsions administered orally in human volunteers showed prolonged plasma drug levels. The multiple emulsions were found suitable for an improved tuberculosis therapy.

Adult↗

PubMed1999

Influence of UV-irradiation on enzymes in mouse ocular lens: in vitro studies.

PURPOSE: In vitro study of the enzymes involved in aerobic, anaerobic and hexose monophosphate shunt in ultraviolet radiation exposed mice lenses. METHOD: Of the selected enzymes, lactic dehydrogenase (LDH) was representative of anaerobic glucose oxidation, succinic dehydrogenase (SDH) of the aerobic oxidation, and Glucose-6-phosphate dehydrogenase (G-6-PDH) of the Hexose Monophosphate (HMP) shunt. Other enzymes studied were ATPase and glutathione reductase (GR). RESULTS: Experiments with mice lenses in vitro showed that transparent lens became opaque following UV-irradiation at 360 nm. Opacification of the lens was accompanied by a change in enzyme activities for energy metabolism. CONCLUSION: These changes were progressive in a manner analogous to sequential morphological changes, which would be crucial in maintaining lens transparency.

Animals↗

PubMed1998

Proniosome based transdermal delivery of levonorgestrel for effective contraception.

A proniosome based transdermal drug delivery system of levonorgestrel (LN) was developed and extensively characterized both in vitro and in vivo. The proniosomal structure was liquid crystalline-compact niosomes hybrid which could be converted into niosomes upon hydration. The system was evaluated in vitro for drug loading, rate of hydration (spontaneity), vesicle size, polydispersity, entrapment efficiency and drug diffusion across rat skin. The effect of composition of formulation, amount of drug, type of Spans, alcohols and sonication time on transdermal permeation profile was observed. The stability studies were performed at 4 degrees C and at room temperature. The biological assay for progestational activity included endometrial assay and inhibition with the formation of corpora lutea. The study demonstrated the utility of proniosomal transdermal patch bearing levonorgestrel for effective contraception.

Administration, Cutaneous↗

PubMed1998

Identification of an immunogenic histone-like protein (HLPMt) of Mycobacterium tuberculosis.

We report the identification of the first histone-like protein of Mycobacterium tuberculosis (MTB) (HLPMt). The T cell blot assay was used to identify antigens of MTB associated with human immune response in healthy contacts. Fraction 21 corresponding to proteins in the molecular weight range of approximately 30 kDa were found to be immunogenic in tuberculin reactors. None of the fractions were found to be immunogenic by this assay in non-reactors to tuberculin. All sera, irrespective of the source, showed reactivity with MTB antigen(s) over a wide molecular weight range (205-->16 kDa). In the present study fraction 21 was processed for the generation of murine polyclonal sera and amino acid sequencing. The sequence of a 16-amino acid long peptide showed a 100% homology with an open reading frame (ORF) in the translated sequence of cosmid cY349 (Sanger Centre, Cambridge, UK). The ORF was predicted to code for a protein of 214 amino acids. Oligonucleotide primers were synthesized based on the nucleotide sequence located at the 5' and 3' regions of the gene. The gene encoding the predicted protein was PCR-amplified, cloned, sequenced and expressed in Escherichia coli as a protein of 28 kDa. The expressed HLPMt protein was shown to react with the polyclonal murine sera originally raised against fraction 21. Human immune response to the recombinant HLPMt protein was demonstrated by its ability to induce lymphoproliferation in peripheral blood derived mononuclear cells, and the presence of anti-HLPMt antibodies in pooled patient sera by immunoblot. The recombinant HLPMt protein elicited a vigorous lymphoproliferative response especially in healthy tuberculin reactors compared to non-reactors and patients of tuberculosis, (P < 0.05). The protein has unique dual domains with homology to both bacterial histone-like proteins (HU) and eukaryotic histone H1. Homology to prokaryotic and eukaryotic deoxyribonucleic acid (DNA)-binding proteins suggested that HLPMt could bind DNA. DNA-binding properties were confirmed by South-Western analysis strongly suggesting an interaction between HLPMt and the MTB chromosome.

Amino Acid Sequence↗

PubMed1998

Brain drug delivery system bearing dopamine hydrochloride for effective management of parkinsonism.

Dopamine hydrochloride bearing positively charged small liposomes was prepared by sonicating the multilamellar vesicles. These vesicles were characterized for their physical attributes (shape, size, charge, drug entrapment efficiency, and drug leakage). The drug release kinetics from the liposomes were also studied and found to be Fickian-type diffusion. In vivo performance of the drug-entrapped liposomes was assessed by periodic measurement of drug- (chlorpromazine) induced catatonia in Sprague-Dowley rats. These results were compared with the plain dopamine HCl and levodopa preparations as well with the marketed formulation of levodopa containing carbidopa (Syndopa). These studies revealed that the dopamine can be effectively delivered to the brain by incorporating it into liposomes, and its degradation in circulation can also be protected. The results of liposomal formulation were found to be superior compared to plain levodopa as well as Syndopa.

Animals↗

PubMed1998

Effects of drug concentration in inner aqueous phase and additives in oleaginous phase on release and bioavailability of isoniazid from multiple emulsion.

The effects of drug concentration in internal aqueous phase of stabilized w/o/w emulsion and additives in oleaginous phase on release characteristics of isoniazid were investigated. The release was significantly effected by both of the formulation variables. The release was enhanced initially with increasing concentration of drug in internal aqueous phase followed by a steady release at high concentration of isoniazid. The release declined substantially in the presence of aluminum tristearate, cetostearyl alcohol, and cholesterol, and it increased with egg lecithin and oleic acid in oily phase. The bioavailability was increased with a multiple-emulsion formulation.

Administration, Oral↗

PubMed1998

A stable multiple emulsion system bearing isoniazid: preparation and characterization.

Multiple emulsions with an oily liquid membrane (w/o/w) bearing isoniazid were prepared by an improved 2 x 2 step emulsification technique. Both of the interfaces of the liquid membrane were stabilized by using microcrystalline cellulose (MCC) in external as well as internal aqueous phases. The emulsions were characterized for droplet size, percent formation of multiple emulsion, release rate effect of Tween-80 in external phase, phase volume ratio on release, and stability during aging at various storage conditions. The droplet size was small and yield of multiple emulsion was fairly good. The increasing concentration of MCC in either internal or external phase increased the droplet size. The system holds promise in tuberculosis therapy.

Antitubercular Agents↗

PubMed1998

Lectin-functionalized multiple emulsions for improved cancer therapy.

Fine-multiple emulsions bearing 6-mercaptopurine (6-MP) in internal aqueous phase were prepared by two step emulsification using sonication technique. It was coated with Concanavalin-A (Con-A) using carbodiimide method to obtain lectin-functionalized multiple emulsions. The Con-A coated multiple emulsion was characterized for antitumour activity on murine leukemia cell line L-1210 in vitro and compared with uncoated multiple emulsion and free drug. An increased uptake and cytotoxicity were observed for Con-A coated multiple emulsion in vitro. The IC50 was decreased upto 4-fold with Con-A coated emulsion. In vivo antitumour activity was seen by recording survival times of mice injected with L-1210 cells i.v. or i.p. The mean survival time was found to increase upon treatment with Con-A coated multiple emulsion. The tumour cell count in the peritoneal cavity was decreased significantly when animal was treated by i.p. route while there was no significant difference when it was treated by i.v. route. The normal peritoneal cells remained unaltered in number and blood parameters were also restored on treatment to tumour bearing mice. The formulation was found to be effective for the treatment of cancer.

Animals↗