1
|
Holden MT, Ram Chhabra S, de Nys R, Stead P, Bainton NJ, Hill PJ, Manefield M, Kumar N, Labatte M, England D, Rice S, Givskov M, Salmond GP, Stewart GS, Bycroft BW, Kjelleberg S, Williams P. Quorum-sensing cross talk: isolation and chemical characterization of cyclic dipeptides from Pseudomonas aeruginosa and other gram-negative bacteria. Mol Microbiol 1999; 33:1254-66. [PMID: 10510239 DOI: 10.1046/j.1365-2958.1999.01577.x] [Citation(s) in RCA: 386] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In cell-free Pseudomonas aeruginosa culture supernatants, we identified two compounds capable of activating an N-acylhomoserine lactone (AHL) biosensor. Mass spectrometry and NMR spectroscopy revealed that these compounds were not AHLs but the diketopiperazines (DKPs), cyclo(DeltaAla-L-Val) and cyclo(L-Pro-L-Tyr) respectively. These compounds were also found in cell-free supernatants from Proteus mirabilis, Citrobacter freundii and Enterobacter agglomerans [cyclo(DeltaAla-L-Val) only]. Although both DKPs were absent from Pseudomonas fluorescens and Pseudomonas alcaligenes, we isolated, from both pseudomonads, a third DKP, which was chemically characterized as cyclo(L-Phe-L-Pro). Dose-response curves using a LuxR-based AHL biosensor indicated that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) activate the biosensor in a concentration-dependent manner, albeit at much higher concentrations than the natural activator N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). Competition studies showed that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) antagonize the 3-oxo-C6-HSL-mediated induction of bioluminescence, suggesting that these DKPs may compete for the same LuxR-binding site. Similarly, DKPs were found to be capable of activating or antagonizing other LuxR-based quorum-sensing systems, such as the N-butanoylhomoserine lactone-dependent swarming motility of Serratia liquefaciens. Although the physiological role of these DKPs has yet to be established, their activity suggests the existence of cross talk among bacterial signalling systems.
Collapse
|
|
26 |
386 |
2
|
Abstract
We report that the flow of a liquid on single-walled carbon nanotube bundles induces a voltage in the sample along the direction of the flow. The voltage that was produced fit a logarithmic velocity dependence over nearly six decades of velocity. The magnitude of the voltage depended sensitively on the ionic conductivity and on the polar nature of the liquid. Our measurements suggest that the dominant mechanism responsible for this highly nonlinear response involves a direct forcing of the free charge carriers in the nanotubes by the fluctuating Coulombic field of the liquid flowing past the nanotubes. We propose an explanation based on pulsating asymmetric ratchets. Our work highlights the device potential for nanotubes as sensitive flow sensors and for energy conversion.
Collapse
|
|
22 |
273 |
3
|
Charlton TS, de Nys R, Netting A, Kumar N, Hentzer M, Givskov M, Kjelleberg S. A novel and sensitive method for the quantification of N-3-oxoacyl homoserine lactones using gas chromatography-mass spectrometry: application to a model bacterial biofilm. Environ Microbiol 2000; 2:530-41. [PMID: 11233161 DOI: 10.1046/j.1462-2920.2000.00136.x] [Citation(s) in RCA: 235] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A method is reported for the quantification of 3-oxoacyl homoserine lactones (3-oxo AHLs), a major class of quorum-sensing signals found in Gram-negative bacteria. It is based on the conversion of 3-oxo AHLs to their pentafluorobenzyloxime derivatives followed by gas chromatography-mass spectrometry (electron capture-negative ion). The method used [13C16]-N-3-oxo-dodecanoyl homoserine lactone ([13C16]-OdDHL) as the internal standard, and its validity was tested by spiking the supernatant and cell fractions with three levels of 3-oxo AHLs, i.e. 1, 10 and 100 ng per sample. These showed the method to be both sensitive (S/N ratio >10:1 for 1 ng) and accurate. The assay was applied to the biofilm and effluent of a green fluorescent protein (GFP)-expressing strain of Pseudomonas aeruginosa (6294) culture grown in flow cells. Biofilm volume was determined for three replicate flow cells by confocal scanning laser microscopy. OdDHL was detected in the biofilm at 632 +/- 381 microM and the effluent at 14 +/- 3 nM. The biofilm concentration is the highest level so far reported for an AHL in a wild-type bacterial system. The next most abundant 3-oxo AHL in the biofilm and effluent was N-3-oxo-tetradecanoyl homoserine lactone (OtDHL) at 40 +/- 15 microM and 1.5 +/- 0.7 nM respectively. OtDHL is unreported for P. aeruginosa and has an activity equivalent to OdDHL in a lasR bioassay. Two other 3-oxo AHLs were detected at lower concentrations: N3-oxo-decanoyl homoserine lactone (ODHL) in the biofilm (3 +/- 2 microM) and effluent (1 +/- 0.1 nM); and N-3-oxo-octanoyl homoserine lactone (OOHL) in the effluent (0.1 +/- 0.1 nM).
Collapse
|
|
25 |
235 |
4
|
Sadiq SA, Thomas FP, Kilidireas K, Protopsaltis S, Hays AP, Lee KW, Romas SN, Kumar N, van den Berg L, Santoro M. The spectrum of neurologic disease associated with anti-GM1 antibodies. Neurology 1990; 40:1067-72. [PMID: 2162499 DOI: 10.1212/wnl.40.7.1067] [Citation(s) in RCA: 213] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We compared anti-GM1 IgM antibody titers in patients with various neurologic diseases and in normal subjects. We found increased titers in patients with lower motor neuron disease, sensorimotor neuropathy, or motor neuropathy with or without multifocal conduction block. In patients with other diseases, titers are similar to those in normal individuals, suggesting that anti-GM1 antibody levels are not increased nonspecifically after neural injury or inflammatory diseases. Anti-GM1 antibodies in many of the patients occur as monoclonal gammopathies, predominantly of lambda light-chain type, but the antibodies are sometimes polyclonal with normal or increased serum IgM concentrations. Most of the anti-GM1 antibodies appear to react with the Gal(beta 1-3)GalNAc epitope which is shared with asialo-GM1 and GD1b, but in some patients the antibodies are more specific for GM1 and associated with motor neuropathy. Patients with motor or sensorimotor peripheral neuropathy or lower motor neuron disease should be tested for anti-GM1 antibodies or anti-Gal(beta 1-3)GalNAc antibodies, as therapeutic reduction in antibody concentrations was reported to result in clinical improvement in some patients.
Collapse
|
Comparative Study |
35 |
213 |
5
|
Hopkins C, Surda P, Kumar N. Presentation of new onset anosmia during the COVID-19 pandemic. Rhinology 2020; 58:295-298. [PMID: 32277751 DOI: 10.4193/rhin20.116] [Citation(s) in RCA: 199] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
INTRODUCTION Anosmia has not been formally recognised as a symptom of COVID-19 infection. Growing anecdotal evidence suggests increasing incidence of cases of anosmia during the current pandemic, suggesting that COVID-19 may cause olfactory dysfunction. The objective was to characterise patients reporting new onset anosmia during the COVID-19 pandemic METHODOLOGY: Design: Survey of 2428 patients reporting new onset anosmia during the COVID-19 pandemic. SETTING Volunteer sample of patients seeking medical advice of recent onset self-diagnosed loss of sense of smell RESULTS: 2428 surveys were completed within 7 days; 64% respondents were under 40. The majority of respondents reported onset of their anosmia in the last week. Of the cohort, 17% did not report any other symptom thought to be associated with COVID-19. In patients who reported other symptoms, 51% reported either cough or fever and therefore met current guidelines for self-isolation. CONCLUSIONS Anosmia is reported in conjunction with well-reported symptoms of coronas virus, but 1 in 6 patients with recent onset anosmia report this as an isolated symptom. This might help identify otherwise asymptomatic carriers of disease and trigger targeted testing. Further study with COVID-19 testing is required to identify the proportion of patients in whom new onset anosmia can be attributed to COVID-19.
Collapse
|
Journal Article |
5 |
199 |
6
|
Gupta PK, Rustgi S, Sharma S, Singh R, Kumar N, Balyan HS. Transferable EST-SSR markers for the study of polymorphism and genetic diversity in bread wheat. Mol Genet Genomics 2003; 270:315-23. [PMID: 14508680 DOI: 10.1007/s00438-003-0921-4] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2003] [Accepted: 08/19/2003] [Indexed: 10/26/2022]
Abstract
Nearly 900 SSRs (simple sequence repeats) were identified among 15,000 ESTs (expressed sequence tags) belonging to bread wheat ( Triticum aestivumL.). The SSRs were defined by their minimum length, which ranged from 14 to 21 bp. The maximum length ranged from 24 to 87 bp depending upon the length of the repeat unit itself (1-7 bp). The average density of SSRs was one SSR per 9.2 kb of EST sequence screened. The trinucleotide repeats were the most abundant SSRs detected. As a representative sample, 78 primer pairs were designed, which were also used to screen the dbEST entries for Hordeum vulgare and Triticum tauschii (donor of the D-genome of cultivated wheat) using a cut-off E (expectation) value of 0.01. On the basis of in silico analysis, up to 55.12% of the primer pairs exhibited transferability from Triticum to Hordeum, indicating that the sequences flanking the SSRs are not only conserved within a single genus but also between related genera in Poaceae. Primer pairs for the 78 SSRs were synthesized and used successfully for the study of (1) their transferability to 18 related wild species and five cereal species (barley, oat, rye, rice and maize); and (2) polymorphism between the parents of four mapping populations available with us. A subset of 20 EST-SSR primers was also used to assess genetic diversity in a collection of 52 elite exotic wheat genotypes. This was done with a view to compare their utility relative to other molecular markers (gSSRs, AFLPs, and SAMPL) previously used by us for the same purpose with the same set of 52 bread wheat genotypes. Although only a low level of polymorphism was detected, relative to that observed with genomic SSRs, the study suggested that EST-SSRs can be successfully used for a variety of purposes, and may actually prove superior to SSR markers extracted from genomic libraries for diversity estimation and transferability.
Collapse
|
Research Support, Non-U.S. Gov't |
22 |
194 |
7
|
Risek B, Guthrie S, Kumar N, Gilula NB. Modulation of gap junction transcript and protein expression during pregnancy in the rat. J Biophys Biochem Cytol 1990; 110:269-82. [PMID: 1688855 PMCID: PMC2116004 DOI: 10.1083/jcb.110.2.269] [Citation(s) in RCA: 191] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The expression of three different gap junction transcripts, alpha 1 (Cx43), beta 1 (Cx32), and beta 2 (Cx26) was examined in several organs during pregnancy in the rat. In all of the organs that were examined--uterus, ovary, heart, and liver--there was a strong correlation between levels of gap junction mRNA and gap junction antigens that were detected at different stages of pregnancy. A striking change in alpha 1 transcript levels (a 5.5-fold increase) was detected in the uterine myometrium on the day before parturition. This elevation of the alpha 1 transcript is thought to be associated with the formation of gap junctions that are required for synchronizing the contractility of the myometrial cells during parturition. 2 d before parturition, there was a detectable elevation of beta 2 transcripts and protein in the endometrial epithelium, which was then followed by a dramatic decrease in beta 2 gap junctional protein on the day before parturition. There was also a substantial elevation of alpha 1 transcripts (a 6.7-fold increase) in the stromal regions of the ovary on the day before parturition that was identical to the temporal pattern of alpha 1 expression in the myometrium. In all three instances--the alpha 1 transcripts in the myometrium, beta 2 transcripts in the endometrium, and alpha 1 transcripts in the ovary--the transcript modulation appeared to be cell specific, because the changes in transcript levels of these three gene products occurred independently of the poly(A) + RNA concentrations at the same pregnancy stages in the respective organs. There were no specific changes detected in gap junction transcript levels in the heart and liver during pregnancy. These observations indicate that a cell-specific modulation of gap junction expression occurs in two regions of the uterus and the ovary during pregnancy. Further, it appears that the same gap junction gene in different organs, such as the alpha 1 gene in the uterine myometrium and the heart, can be differentially regulated.
Collapse
|
research-article |
35 |
191 |
8
|
Abstract
Hydrogels are crosslinked hydrophilic polymer structures that can imbibe large amounts of water or biological fluids. Hydrogels are one of the upcoming classes of polymer-based systems that embrace numerous biomedical and pharmaceutical applications. This review discusses various parameters of hydrogels such as surface properties, water content and swelling behavior, effect of nature of polymer, ionic content, and thermodynamics, all of which can influence the biomedical usage of hydrogels. Meanwhile, intelligent or environment-sensitive hydrogels and bioadhesive hydrogels continue to be important materials for medical applications; therefore, a part of this review is devoted to some of their important classes. Hydrogels are extensively used for various biomedical applications--tissue engineering, molecular imprinting, wound dressings materials, immunoisolation, drug delivery, etc. Thus, this review aims to throw light on the numerous applications that hydrogels have in the biomedical arena.
Collapse
|
Review |
20 |
184 |
9
|
Josephs KA, Ahlskog JE, Klos KJ, Kumar N, Fealey RD, Trenerry MR, Cowl CT. Neurologic manifestations in welders with pallidal MRI T1 hyperintensity. Neurology 2005; 64:2033-9. [PMID: 15888601 DOI: 10.1212/01.wnl.0000167411.93483.a1] [Citation(s) in RCA: 183] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Neurologic symptoms have been attributed to manganese fumes generated during welding. Increased T1 MRI signal in the basal ganglia is a biologic marker of manganese accumulation. Recent studies have associated welding and parkinsonism, but generally without MRI corroboration. OBJECTIVE To characterize the clinical and neuropsychological features of patients with MRI basal ganglia T1 hyperintensity, who were ultimately diagnosed with neurotoxicity from welding fumes. METHODS The medical records of welders referred to the Department of Neurology with neurologic problems and basal ganglia T1 hyperintensity were reviewed. RESULTS All eight patients were male career welders with increased T1 basal ganglia signal on MRI of the brain. Several different clinical syndromes were recognized: a parkinsonian syndrome (three patients), a syndrome of multifocal myoclonus and limited cognitive impairment (two patients), a mixed syndrome with vestibular-auditory dysfunction (two patients), and minor subjective cognitive impairment, anxiety, and sleep apnea (one patient). Neuropsychometric testing suggested subcortical or frontal involvement. Inadequate ventilation or lack of personal respiratory protection during welding was a common theme. CONCLUSIONS Welding without proper protection was associated with syndromes of parkinsonism, multifocal myoclonus, mild cognitive impairment, and vestibular-auditory dysfunction. The MRI T1 hyperintensity in the basal ganglia suggests that these may have been caused by manganese neurotoxicity.
Collapse
|
Journal Article |
20 |
183 |
10
|
Abstract
Recently, block copolymers have got tremendous impetus on the ongoing research in the area of drug delivery technology, due to their capability to provide a biomaterial having a broad range of amphiphilic characteristics, as well as targeting the drugs to specific site. This article is an attempt to review applications of block copolymers in surface modification, drug targeting, nano and microparticles, hydrogels, micelles etc. The physicochemical properties of block copolymers and various synthetic routes for block copolymers are also discussed.
Collapse
|
Review |
24 |
182 |
11
|
Abstract
BACKGROUND Superficial siderosis (SS) of the CNS is caused by repeated slow hemorrhage into the subarachnoid space with resultant hemosiderin deposition in the subpial layers of the brain and spinal cord. Despite extensive investigations, the cause of bleeding is frequently undetermined. OBJECTIVES To review the clinical and imaging features of 30 consecutive patients with SS and provide insights into the underlying causes of subarachnoid bleeding in this disabling disorder. METHODS The authors reviewed the medical records of 30 consecutive patients with clinical and MRI evidence of SS. RESULTS The commonest neurologic manifestations included gait ataxia and hearing impairment. A clinical history of subarachnoid hemorrhage was relatively rare. Possible predisposing conditions were identified on history in 22 patients, the commonest being a prior trauma (15 patients). In addition to the characteristic MRI findings of SS, 18 patients had abnormalities on MRI possibly related to chronic bleeding. The most common of these was the presence of a fluid-filled collection in the spinal canal seen in 14 patients. CONCLUSIONS A history of prior subarachnoid hemorrhage is often absent in patients with superficial siderosis (SS). A past history of trauma is common. Prior intradural surgery may be an additional risk factor. Xanthochromia or the presence of red blood cells in the CSF is a common finding. Only rarely does angiography demonstrate the bleeding source. The presence of a fluid-filled collection in the spinal canal is a common finding on MRI and is likely related to the SS. With longitudinally extensive cavities, a dynamic CT myelogram may help localize the defect and direct the site of laminectomy. Surgical repair of a dural defect, if present, should be considered. Surgical correction of bleeding should be documented by CSF examination months after surgery. Friable vessels in the dural defect are a possible source of the chronic bleeding.
Collapse
|
Journal Article |
19 |
166 |
12
|
Pandey S, Ranade SA, Nagar PK, Kumar N. Role of polyamines and ethylene as modulators of plant senescence. J Biosci 2000; 25:291-9. [PMID: 11022232 DOI: 10.1007/bf02703938] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Under optimal conditions of growth, senescence, a terminal phase of development, sets in after a certain physiological age. It is a dynamic and closely regulated developmental process which involves an array of changes at both physiological and biochemical levels including gene expression. A large number of biotic and abiotic factors accelerate the process. Convincing evidence suggests the involvement of polyamines (PAs) and ethylene in this process. Although the biosynthetic pathways of both PAs and ethylene are interrelated, S-adenosylmethionine (SAM) being a common precursor, their physiological functions are distinct and at times antagonistic, particularly during leaf and flower senescence and also during fruit ripening. This provides an effective means for regulation of their biosynthesis and also to understand the mechanism by which the balance between the two can be established for manipulating the senescence process. The present article deals with current advances in the knowledge of the interrelationship between ethylene and PAs during senescence which may open up new vistas of investigation for the future.
Collapse
|
Review |
25 |
148 |
13
|
Abstract
Nestorone(R) (Nestorone 16-methylene-17alpha-acetoxy-19-norpregn-4-ene-3,20-dione), formerly referred to as ST 1435, is a potent progestin when given parenterally via sustained release formulations. The pharmacological profile of Nestorone was compared with that of levonorgestrel and 3-keto-desogestrel by steroid receptor binding studies and by in vivo bioassays in rats and rabbits. 3-Keto-desogestrel showed the highest binding affinity to progesterone receptors (PR) followed by Nestorone, levonorgestrel, and progesterone. The binding affinity of Nestorone to androgen receptors (AR) was 500- to 600-fold less than that of testosterone. However, both levonorgestrel and 3-keto-desogestrel showed significant binding (40 to 70% of testosterone) to AR. None of the progestins bound to estrogen receptors (ER). The progestational activity of Nestorone, levonorgestrel, and progesterone was compared using McPhail index in immature rabbits and pregnancy maintenance and ovulation inhibition tests in rats after subcutaneous (s.c.) administration. In all three tests, Nestorone was the most potent progestin. The progestational activity of Nestorone was also compared after oral and s.c. administration in rabbits. The potency of Nestorone was over 100-fold higher upon s.c. administration than via the oral route. The androgenic activity of progestins, based on the stimulation of ventral prostate (androgenic target) and levator ani (anabolic target) growth in castrated immature rats, showed good correlation with their binding affinity to AR. Nestorone showed no androgenic or anabolic activity. Nestorone did not bind to sex hormone binding globulin (SHBG), whereas both levonorgestrel and 3-keto-desogestrel showed significant binding to SHBG. The estrogenic/antiestrogenic activity of Nestorone was investigated in immature ovariectomized rats. In contrast to estradiol and levonorgestrel, Nestorone showed no uterotropic activity in ovariectomized rats. Despite significant binding to glucocorticoid receptors (GR), Nestorone showed no glucocorticoid activity in vivo. It is concluded that a strong progestational activity, combined with lack of androgenic, estrogenic, and glucocorticoid-like activities, confer special advantages to Nestorone for use in contraception and hormone replacement therapy.
Collapse
|
Comparative Study |
25 |
140 |
14
|
Heikkilä T, Salonen J, Tuura J, Hamdy MS, Mul G, Kumar N, Salmi T, Murzin DY, Laitinen L, Kaukonen AM, Hirvonen J, Lehto VP. Mesoporous silica material TUD-1 as a drug delivery system. Int J Pharm 2007; 331:133-8. [PMID: 17046183 DOI: 10.1016/j.ijpharm.2006.09.019] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 09/11/2006] [Accepted: 09/14/2006] [Indexed: 11/26/2022]
Abstract
For the first time the feasibility of siliceous mesoporous material TUD-1 (Technische Universiteit Delft) for drug delivery was studied. Model drug, ibuprofen, was adsorbed into TUD-1 mesopores via a soaking procedure. Characterizations with nitrogen adsorption, XRD, TG, HPLC and DSC demonstrated the successful inclusion of ibuprofen into TUD-1 host. The amount of ibuprofen adsorbed into the nanoreservoir of TUD-1 material was higher than reported for other mesoporous silica drug carriers (drug/carrier 49.5 wt.%). Drug release studies in vitro (HBSS buffer pH 5.5) demonstrated a fast and unrestricted liberation of ibuprofen, with 96% released at 210 min of the dissolution assay. The drug dissolution profile of TUD-1 material with the random, foam-like three-dimensional mesopore network and high accessibility to the dissolution medium was found to be much faster (kinetic constant k = 10.7) and more diffusion based (release constant n = 0.64) compared to a mesoporous MCM-41 material with smaller, unidirectional mesopore channels (k = 4.7, n = 0.71). Also, the mesoporous carriers were found to significantly increase the dissolution rate of ibuprofen, when compared to the pure crystalline form of the drug (k = 0.6, n = 0.96). TUD-1 was constituted as a potential drug delivery device with fast release property, with prospective applications in the formulation of poorly soluble drug compounds.
Collapse
|
|
18 |
136 |
15
|
Proctor R, Kumar N, Stein A, Moles D, Porter S. Oral and dental aspects of chronic renal failure. J Dent Res 2005; 84:199-208. [PMID: 15723858 DOI: 10.1177/154405910508400301] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The present article reviews, in detail, the current knowledge of the oral and dental aspects of chronic renal failure (CRF). Worldwide, increasing numbers of persons have CRF; thus, oral health care staffs are increasingly likely to provide care for patients with such disease. Chronic renal failure can give rise to a wide spectrum of oral manifestations, affecting the hard or soft tissues of the mouth. The majority of affected individuals have disease that does not complicate oral health care; nevertheless, the dental management of such individuals does require that the clinician understand the multiple systems that can be affected. The clinician should also consider the adverse side-effects of drug therapy and appropriate prescribing, in view of compromised renal clearance.
Collapse
|
Review |
20 |
134 |
16
|
Sharma C, Kumar N, Pandey R, Meis JF, Chowdhary A. Whole genome sequencing of emerging multidrug resistant Candida auris isolates in India demonstrates low genetic variation. New Microbes New Infect 2016; 13:77-82. [PMID: 27617098 PMCID: PMC5006800 DOI: 10.1016/j.nmni.2016.07.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/27/2016] [Accepted: 07/01/2016] [Indexed: 11/26/2022] Open
Abstract
Candida auris is an emerging multidrug resistant yeast that causes nosocomial fungaemia and deep-seated infections. Notably, the emergence of this yeast is alarming as it exhibits resistance to azoles, amphotericin B and caspofungin, which may lead to clinical failure in patients. The multigene phylogeny and amplified fragment length polymorphism typing methods report the C. auris population as clonal. Here, using whole genome sequencing analysis, we decipher for the first time that C. auris strains from four Indian hospitals were highly related, suggesting clonal transmission. Further, all C. auris isolates originated from cases of fungaemia and were resistant to fluconazole (MIC >64 mg/L).
Collapse
|
Journal Article |
9 |
132 |
17
|
Kumar N, Koski G, Harada M, Aikawa M, Zheng H. Induction and localization of Plasmodium falciparum stress proteins related to the heat shock protein 70 family. Mol Biochem Parasitol 1991; 48:47-58. [PMID: 1779989 DOI: 10.1016/0166-6851(91)90163-z] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Induction of heat shock-related stress proteins Pfhsp and Pfgrp, similar in sequence to hsp70 (heat shock protein) and grp78 (glucose-regulated protein), respectively, was studied in culture-derived parasite Plasmodium falciparum. Elevation in temperature from 26 degrees C to 37 degrees C and higher caused significant induction of Pfhsp with a moderate effect on the synthesis of Pfgrp also. Synthesis of Pfgrp, however, was not induced by partial glucose deprivation. On the contrary, lack of glucose in the medium resulted in cessation of protein synthesis in the parasites. Other known inducers of grp synthesis in mammalian cells, i.e., calcium ionophore A23187 and inhibitors of glycosylation (tunicamycin, 2-deoxy glucose) were also without any apparent effect on the synthesis of Pfgrp. Heat shock-induced responses were transient in nature: removal of stress caused repression of these responses. The effect of glucose deprivation was only partially reversible with better recovery if parasites were subjected to glucose starvation at 26 degrees C than at 37 degrees C. Northern blot analysis and in vitro translation of mRNA revealed a parallel increase in the levels of mRNA for Pfhsp upon heat shock. Immuno-gold electron microscopy with cultured parasites revealed nuclear location of Pfhsp and primarily cytoplasmic (probably endoplasmic reticulum) location of Pfgrp. These findings suggest that SDEL (carboxy terminal sequence of Pfgrp) might play a similar role in the cellular localization of Pfgrp as does the sequence KDEL in mammalian cells and HDEL in yeast.
Collapse
|
|
34 |
132 |
18
|
Hume EBH, Baveja J, Muir B, Schubert TL, Kumar N, Kjelleberg S, Griesser HJ, Thissen H, Read R, Poole-Warren LA, Schindhelm K, Willcox MDP. The control of Staphylococcus epidermidis biofilm formation and in vivo infection rates by covalently bound furanones. Biomaterials 2004; 25:5023-30. [PMID: 15109864 DOI: 10.1016/j.biomaterials.2004.01.048] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2001] [Accepted: 01/20/2004] [Indexed: 11/28/2022]
Abstract
In order to overcome the continuing infection rate associated with biomaterials, the use of covalently bound furanones as an antibiofilm coating for biomaterials has been investigated. Furanones have previously been shown to inhibit growth of Gram-positive and Gram-negative bacteria. The aim of these studies were to covalently bind furanones to polymers and to test their efficacy for inhibiting biofilm formation of Staphylococcus epidermidis and in vivo infection rate. Two methods of covalent attachment of furanones were used. The first, a co-polymerisation with a styrene polymer, and second, a plasma-1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) reaction to produce furanone-coated catheters. Biofilm formation by S. epidermidis in vitro was inhibited by 89% for polystryene-furanone disks and by 78% by furanone-coated catheters (p<0.01). In an in vivo sheep model we found furanones were effective at controlling infection for up to 65 days. Furanones have potential to be used as a coating for biomaterials to control infection caused by S. epidermidis.
Collapse
|
Research Support, Non-U.S. Gov't |
21 |
124 |
19
|
Heikkilä T, Salonen J, Tuura J, Kumar N, Salmi T, Murzin DY, Hamdy MS, Mul G, Laitinen L, Kaukonen AM, Hirvonen J, Lehto VP. Evaluation of mesoporous TCPSi, MCM-41, SBA-15, and TUD-1 materials as API carriers for oral drug delivery. Drug Deliv 2007; 14:337-47. [PMID: 17701523 DOI: 10.1080/10717540601098823] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The feasibility of four mesoporous materials composed of biocompatible Si (TCPSi) or SiO(2) (MCM-41, SBA-15, and TUD-1) were evaluated for oral drug delivery applications. The main focus was to study the effect of the materials different pore systems (unidirectional/2D/3D) and their pore diameters, pore size distributions, pore volumes on the maximal drug load capacity, and release profiles of a loaded active pharmaceutical ingredient. Ibuprofen was used as the model drug. The total pore volume of the mesoporous solid was the main factor limiting the maximum drug load capacity, with SBA-15 reaching a very high drug load of 1:1 in weight due to its high pore volume. Dissolution experiments were performed in HBSS buffers of pH 5.5, 6.8, and 7.4 to mimic the conditions in the small intestine. At pH 5.5 the dissolution rate of ibuprofen released from the mesoporous carriers was significantly faster compared with the standard bulk ibuprofen (86-63% versus 25% released at 45 min), with the fastest release observed from the 3D pore network of TUD-1 carrier. The utilization of mesoporous carriers diminished the pH dependency of ibuprofen dissolution (pK(a) = 4.42), providing an interesting prospect for the formulation of poorly soluble drug compounds.
Collapse
|
Research Support, Non-U.S. Gov't |
18 |
123 |
20
|
Graves PM, Carter R, Burkot TR, Quakyi IA, Kumar N. Antibodies to Plasmodium falciparum gamete surface antigens in Papua New Guinea sera. Parasite Immunol 1988; 10:209-18. [PMID: 3287282 DOI: 10.1111/j.1365-3024.1988.tb00215.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sera from individuals living in malaria endemic areas of Papua New Guinea were tested for their effect on infectivity of Plasmodium falciparum gametocytes grown in culture to Anopheles freeborni mosquitoes. Consistent reduction of infectivity to less than 5% of control was observed with nine out of the 41 sera from the endemic area tested and also with three out of seven sera tested from individuals rarely exposed to malaria infection. Gamete surface antigens recognized by the sera were investigated by immunoprecipitation from 125I surface-labelled gametes extracted in SDS and Triton X-100. The main antigens recognized were of the same mol. wt (230, 48 and 45 kD) as those known to be targets of transmission-blocking monoclonal antibodies. A significant negative correlation was observed between the total ct/min immunoprecipitated from surface-labelled gametes by the sera and the average number of oocysts per gut observed in membrane feeding experiments with these sera. Spearmann's rank correlation coefficient indicated that suppression of infectivity correlated strongly with the presence of antibodies against the 230 kD protein; there was no significant correlation between suppression and antibodies to the 48/45 kD proteins. The antibody response to the different gamete surface antigens varied greatly in sera from the endemic areas suggesting that individuals respond differently to each gamete antigen.
Collapse
|
|
37 |
122 |
21
|
Couture RM, Rose J, Kumar N, Mitchell K, Wallschläger D, Van Cappellen P. Sorption of arsenite, arsenate, and thioarsenates to iron oxides and iron sulfides: a kinetic and spectroscopic investigation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:5652-5659. [PMID: 23607702 DOI: 10.1021/es3049724] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sorption to iron (Fe) minerals determines the fate of the toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown to dominate aqueous As speciation under a range of environmentally relevant conditions, thus highlighting the need for a quantitative understanding of their sorption behavior. We conducted batch experiments to measure the time-dependent sorption of two S-substituted arsenate species, mono- and tetrathioarsenate, and compared it to the sorption of arsenite and arsenate, in suspensions containing 2-line ferrihydrite, goethite, mackinawite, or pyrite. All four As species strongly sorbed to ferrihydrite. For the other sorbents, binding of the thiolated As species was generally lower compared to arsenate and arsenite, with the exception of the near instantaneous and complete sorption of monothioarsenate to pyrite. Analysis of the X-ray absorption spectroscopy (XAS) spectra of sorbed complexes implied that monothioarsenate binds to Fe oxides as a monodentate, inner-sphere complex. In the presence of Fe sulfides, mono- and tetrathioarsenate were both unstable and partially reduced to arsenite. Adsorption of the thiolated As species to the Fe sulfide minerals also caused the substitution of surface sulfur (S) atoms by As and the formation of As-Fe bonds.
Collapse
|
|
12 |
109 |
22
|
Brehm KE, Kumar N, Thulke HH, Haas B. High potency vaccines induce protection against heterologous challenge with foot-and-mouth disease virus. Vaccine 2008; 26:1681-7. [PMID: 18313814 DOI: 10.1016/j.vaccine.2008.01.038] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 01/10/2008] [Accepted: 01/11/2008] [Indexed: 10/22/2022]
Abstract
In a series of three homologous and eight heterologous challenge experiments, it was shown that high potency vaccines against foot-and-mouth disease (FMD) serotype A can induce protection even against heterologous challenge infection with viruses that give low r-values with the vaccine strains. The challenge virus specific neutralizing antibody response on the day of challenge (21 days post vaccination) generally correlated with protection.
Collapse
|
Research Support, Non-U.S. Gov't |
17 |
104 |
23
|
Abstract
Despite extensive imaging, a source of bleeding is often not evident during the evaluation of patients with superficial siderosis (SS) of the central nervous system. An intraspinal fluid-filled collection of variable dimensions is frequently seen on spine MR imaging in patients with idiopathic SS. A similar finding has also been reported in patients with craniospinal hypotension. This review discusses the role of multitechnique imaging in the work-up of patients with SS and focuses on recent developments.
Collapse
|
Review |
16 |
102 |
24
|
Baveja JK, Willcox MDP, Hume EBH, Kumar N, Odell R, Poole-Warren LA. Furanones as potential anti-bacterial coatings on biomaterials. Biomaterials 2004; 25:5003-12. [PMID: 15109862 DOI: 10.1016/j.biomaterials.2004.02.051] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 05/13/2003] [Indexed: 11/26/2022]
Abstract
A major barrier to the long-term use of medical devices is development of infection. Staphylococcus epidermidis is one of the most common bacterial isolates from these infections with biofilm formation being their main virulence factor. Currently, antibiotics are used as the main form of therapy. However with the emergence of staphylococcal resistance, this form of therapy is fast becoming ineffective. In this study, the ability of a novel furanone antimicrobial compound to inhibit S. epidermidis adhesion and slime production on biomaterials was assessed. Furanones were physically adsorbed to various biomaterials and bacterial load determined using radioactivity. Slime production was assessed using a colorimetric method. Additionally, the effect of the furanone coating on material surface characteristics such as hydrophobicity and surface roughness was also investigated. The results of this study indicated that there was no significant change in the material characteristics after furanone coating. Bacterial load on all furanone-coated materials was significantly reduced (p<0.001) as was slime production (p<0.001). There is a potential for furanone-coated biomaterials to be used to reduce medical device-associated infections.
Collapse
|
Research Support, Non-U.S. Gov't |
21 |
102 |
25
|
Andrews JI, Kumar N, van den Brom RH, Olkkola KT, Roest GJ, Wright PM. A large simple randomized trial of rocuronium versus succinylcholine in rapid-sequence induction of anaesthesia along with propofol. Acta Anaesthesiol Scand 1999; 43:4-8. [PMID: 9926179 DOI: 10.1034/j.1399-6576.1999.430102.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Rocuronium has an onset of action more rapid than other non-depolarizing neuromuscular blocking agents, but it is unclear whether it and succinylcholine give equivalent intubating conditions during rapid-sequence induction of anaesthesia. We performed this study to answer the question--are there clinically relevant differences between the use of rocuronium and succinylcholine to secure acceptable intubating conditions during rapid-sequence induction of anaesthesia with propofol? METHODS Anaesthesia was induced using propofol 2.5 mg/kg in 349 ASA physical status grade I-IV patients who were undergoing either elective or emergency surgery. Propofol was followed immediately by either rocuronium 0.6 or 1 mg/kg or succinylcholine 1.0 mg/kg (randomly selected). Fifty seconds after the end of muscle relaxant injection laryngoscopy was performed and intubating conditions were graded by an experienced anaesthetist blind to the muscle relaxant allocation. This study design was selected so that a 10% difference in clinically acceptable intubating conditions between drugs would be detectable. RESULTS In this setting rocuronium 1.0 mg/kg provided superior intubating conditions compared with rocuronium 0.6 mg/kg. The incidence of clinically acceptable intubating conditions with rocuronium 1.0 mg/kg and succinylcholine 1.0 mg/kg was 93.2% and 97.1% respectively, the difference being -3.9% (95% C.I. -9.7% to 1.9%). CONCLUSION Rocuronium 1.0 mg/kg given along with propofol in a rapid-sequence induction of anaesthesia is clinically equivalent to succinylcholine 1.0 mg/kg.
Collapse
|
Clinical Trial |
26 |
101 |