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Biomedical subjects

Rakesh K Gupta

Publications and source records attributed to Rakesh K Gupta.

At least 37 records · Page 2Linked to original sources
PubMed2005

Diagnosis of bacterial cerebellitis: diffusion imaging and proton magnetic resonance spectroscopy.

Diffusion-weighted imaging and in vivo proton magnetic resonance spectroscopy ((1)H magnetic resonance spectroscopy) have demonstrated great potential in differentiating intracranial lesions of various pathologies. This report describes a case of a 12-year-old child with cerebellitis and subdural empyema that manifested presence of succinate, acetate, lactate, and amino acids on in vivo (1)H magnetic resonance spectroscopy from a large area of restricted diffusion in the vermis on diffusion-weighted imaging, a finding specific for bacteria-induced infection. The child made a complete clinical and imaging recovery on conservative management.

Central Nervous System Bacterial Infections↗
PubMed2005

Diffusion tensor imaging in late posttraumatic epilepsy.

PURPOSE: The main objective of this study was to use diffusion tensor imaging (DTI) to search and quantify the extent of abnormality beyond the obvious lesions seen on the T2 and fluid-attenuation inversion recovery (FLAIR) magnetic resonance images in patients with chronic traumatic brain injury (TBI) with and without epilepsy. METHODS: DTI was performed on 23 chronic TBI patients (with late posttraumatic epilepsy, n=14; without epilepsy, n=9) and 11 age-matched controls. The ratios of fractional anisotropy (FA) and mean diffusivity (MD) between the regions of interest beyond the T2/FLAIR-visualized abnormality and the corresponding contralateral normal-appearing region were calculated. FA and MD ratios were compared for relative changes in these parameters among the TBI subjects with and without epilepsy and controls. Tissue volumes exhibiting abnormalities on DTI also were measured in these patients. RESULTS: The mean regional FA ratio was significantly lower, whereas the mean regional MD value was higher in patients with TBI compared with controls. The mean regional FA ratio was significantly lower in TBI patients with epilepsy (0.57+/-0.059) than in those without epilepsy (0.68+/-0.039). Although the regional MD ratio was higher in TBI patients with epilepsy (1.15+/-0.140) relative to those without epilepsy (1.09+/-0.141), the difference did not reach statistical significance. The tissue volume with low FA value also was found to be higher in TBI patients with epilepsy than without. CONCLUSIONS: Severity of injury as predicted by the DTI-derived increased volume of microstructure damage is associated with delayed posttraumatic epilepsy in TBI patients. These findings could be valuable in predicting epileptogenesis in patients with chronic TBI.

Adolescent↗
PubMed2005

Use of Saccharomyces cerevisiae BLYES expressing bacterial bioluminescence for rapid, sensitive detection of estrogenic compounds.

An estrogen-inducible bacterial lux-based bioluminescent reporter was developed in Saccharomyces cerevisiae for applications in chemical sensing and environmental assessment of estrogen disruptor activity. The strain, designated S. cerevisiae BLYES, was constructed by inserting tandem estrogen response elements between divergent yeast promoters GPD and ADH1 on pUTK401 (formerly pUA12B7) that constitutively express luxA and luxB to create pUTK407. Cotransformation of this plasmid with a second plasmid (pUTK404) containing the genes required for aldehyde synthesis (luxCDE) and FMN reduction (frp) yielded a bioluminescent bioreporter responsive to estrogen-disrupting compounds. For validation purposes, results with strain BLYES were compared to the colorimetric-based estrogenic assay that uses the yeast lacZ reporter strain (YES). Strains BLYES and YES were exposed to 17beta-estradiol over the concentration range of 1.2 x 10(-8) through 5.6 x 10(-12) M. Calculated 50% effective concentration values from the colorimetric and bioluminescence assays (n = 7) were similar at (4.4 +/- 1.1) x 10(-10) and (2.4 +/- 1.0) x 10(-10) M, respectively. The lower and upper limits of detection for each assay were also similar and were approximately 4.5 x 10(-11) to 2.8 x 10(-9) M. Bioluminescence was observed in as little as 1 h and reached its maximum in 6 h. In comparison, the YES assay required a minimum of 3 days for results. Strain BLYES fills the niche for rapid, high-throughput screening of estrogenic compounds and has the ability to be used for remote, near-real-time monitoring of estrogen-disrupting chemicals in the environment.

Biological Assay↗
PubMed2005

Paraplegia after intracord injection during attempted epidural steroid injection in an awake-patient.

UNLABELLED: Epidural steroid injection is recommended in patients with back ache from spinal and radicular pain or pain suggestive of radiculopathy. During needle placement and injections, clinicians often rely on the patient's complaint of paresthesia or shooting pain along the nerve root, dura, or cord in case a needle pierces these areas. We report the accidental intracord injection of steroid solution during epidural block using fluoroscopy in a conscious patient, which caused paraplegia. This case suggests failure of undue reliance on a patient reporting pain in the vicinity of needle puncturing the spinal cord structures. IMPLICATIONS: Intracord injection of triamcinolone acetate and local anesthetic, resulting in permanent paraplegia, may occur in conscious patients.

Humans↗
PubMed2005

Conical working tube: a special device for endoscopic surgery of herniated lumbar discs.

OBJECT: The instrumentation for endoscopic discectomy continues to evolve to allow for acceptable clinical outcomes and expanding applications. The authors describe their experience in using a conical working tube equipped with a guide for angular entry of the telescope to perform endoscopic discectomy in patients with lumbar disc herniation. METHODS: Fifty-one patients (38 men and 13 women) with herniated lumbar discs underwent endoscopic lumbar surgery during the past 2.5 years at the authors' institutions. A conical working tube was inserted over sequential coaxial dilators via a muscle-splitting approach. Conventional neurosurgical instruments were used in conjunction with an angled insertion telescope. Endoscopic discectomy was performed at the L1-2 (one case), L3-4 (two cases), L4-5 (32 cases), and L5-S1 (18 cases) levels. The surgical approach was bilateral in two patients: bilateral L4-5 in one, and right L4-5 and left L5-S1 in the other. The remaining patient suffered adjacent two-level (right-sided L4-5 and L5-S1) herniations. Outcome was assessed at a mean of 11 months after surgery by using modified Macnab criteria. Outcomes were excellent in 46 (90%), fair in three (6%), and poor in two patients (4%). Complications occurred in four patients and included a dural tear in one case, postoperative neurological deterioration in two, and discitis in two; in two of these patients open surgical exploration was required. CONCLUSIONS: A separate angled entry of the telescope shortens the effective length of the working sheath and creates a better working space, thereby allowing greater instrument maneuverability and ability to use conventional neurosurgical instruments. In addition, use of this telescope in other endoscopic procedures reduces overall cost of instrumentation and treatment, and results are comparable to those reported in association with microscopic lumbar discectomy.

Adolescent↗
PubMed2005

High fractional anisotropy in brain abscesses versus other cystic intracranial lesions.

BACKGROUND AND PURPOSE: It is known that intracranial mass lesions are relatively isotropic on diffusion-weighted imaging. The purpose of this study is to report an unusually high fractional anisotropy (FA) and mean diffusivity (D(av)) in the cavity of the brain abscess compared with other cystic lesions. METHODS: We performed diffusion tensor imaging (DTI) in 12 patients with cystic intracranial lesions (pyogenic abscess, n = 5; cysticercus cysts, n = 2; and low-grade astrocytoma, n = 5). Mean FA, D(av) from the lesion core, perifocal edema, and corresponding contralateral normal-appearing regions were measured and compared for relative changes in these parameters. In the abscess cases, we placed regions of interest on areas with FA >0.2 and FA <0.2 to get FA and D(av) values. RESULTS: There were two patterns of FA values in the abscess cavity in all five patients. Part of the abscess showed mean FA = 0.440 +/- 0.135, with D(av) = (0.993 +/- 0.185) x 10(-3) mm(2)/s, whereas other parts had FA = 0.131 +/- 0.039 with D(av) = (0.824 +/- 0.183) x 10(-3) mm(2)/s. The cystic tumors and neurocysticercosis showed very high D(av) = (2.806 +/- 0.25, 2.654 +/- 0.35)x 10(-3) mm(2)/s, with low FA = (0.108 +/- 0.037, 0.08 +/- 0.01), respectively. CONCLUSION: Brain abscess cavity shows regions of increased FA values with restricted mean diffusivity compared with other cystic intracranial lesions. This information may prevent misinterpretation of the DTI information as white matter fiber bundle abnormalities associated with mass lesions.

Adolescent↗
PubMed2004

Prediction of viability of porcine neurocysticercosis with proton magnetic resonance spectroscopy: correlation with histopathology.

Neurocysticercosis (NCC) is the most frequent parasitic disease of central nervous system. In our earlier study, we had observed creatine [(creatine + phosphocreatine); (tCr)] on ex vivo proton MR spectroscopy (1H MRS) in some of the cysticercus cyst fluid samples obtained from swine's brain parenchyma. In current study, swine brains of freshly slaughtered animals naturally infected with NCC were subjected to ex vivo magnetic resonance (MR) imaging on a 1.5Tesla MR system. Cysticercus cysts (n = 12) were removed from these brains and were labeled depending upon presence or absence of edema around cysts as observed on imaging. Cysticercus cyst fluid (100 microl) was subjected to different 1H MRS experiments and results were compared with histopathological examinations to look for any relationship between tCr and parameters like quantification of musculature, and cellular infiltration in wall of the parasite. Histopathology of cyst wall was categorized into two groups based on cellular characteristics and the amount of musculature. Grade I cysts (n = 5) with no or minimal inflammation and large amount of musculature showed tCr on 1H MRS. However, grade II cysts (n = 7) with profuse inflammation and less amount of musculature in the cyst wall lacked tCr. Higher amount of musculature in grade I cysts was associated with higher concentration of tCr in the cyst fluid (r2 = 0.93, P = 0.007). Creatine appears to be a marker of innocuous and viable NCC.

Animals↗
PubMed2004

Correlative MR imaging and histopathology in porcine neurocysticercosis.

PURPOSE: To examine whether all the histopathologically seen features of cysticercus cysts excised from brain of swine naturally infected with neurocysticercosis during its evolution are actually visible on magnetic resonance imaging (MRI). MATERIALS AND METHODS: Five swine naturally infected with cerebral cysticercosis were subjected to fast spin-echo (SE) T2, SE T1, fluid attenuated inversion recovery imaging, T1-weighted magnetization transfer (MT), and postcontrast T1-weighted MT sequences on MRI. These animals were sacrificed after imaging and ex vivo imaging of the intact excised brain using the same imaging protocol was also performed. Grossing of these brains was done similar to the ex vivo imaging planes. Numeral density and external appearance of each cyst and scolex were evaluated on each pulse sequence. Amount of pericystic edema, if present, was also assessed. On histopathology, cellular characteristics, inflammatory response, and the extent of edema, if present, in the brain parenchyma around the cysts were graded. Cysts were categorized into viable, early, and late degenerated on histopathology. The MRI features of each cyst were correlated with their histopathologic findings. RESULTS: Out of 31 cysts, eight were found to be viable, 13 early degenerated, and 10 late degenerated on histopathology. T2-weighted imaging demonstrated all the cysts while T1-weighted imaging showed 97% of the cysts. Scolex was seen in 90.3% and 93.5% of the cysts on T2- and T1-weighted images, respectively. Minimal edema (grade I) and inflammation in degenerating cysts present on histopathology was not visible on MRI. All but one of eight degenerated cysts, which showed enhancement on postcontrast MRI, had edema on imaging as well as on histopathology. CONCLUSION: T2-weighted MRI demonstrated all the cysts that were visible on histopathology. Non-enhancement of some of the degenerated cysts along with absence of edema on MRI is likely to underestimate the staging of neurocysticercosis evolution, and these early degenerating cysts may be misdiagnosed as in viable stage.

Animals↗
PubMed2004

A graphical user interface for automatic image registration software designed for radiotherapy treatment planning.

Medical imaging forms a vital component of radiotherapy treatment planning and its evaluation. The integration of the useful data obtained from multiple imaging modalities for radiotherapy planning is achieved by image registration softwares. In radiotherapy planning systems, normally the computed tomography (CT) slices are kept as a standard upon which other modality images (magnetic resonance imaging [MRI], single photon emission computed tomography [SPECT], positron emission tomography [PET], etc.) are aligned--automatically or interactively. Following validation of successful registration, they are resampled and reformatted, as per the requirements. This paper defines the minimum requirements of automatic image registration software for 3-dimensional (3D) radiotherapy planning and describes the implementation of a suitable graphical user interface developed in Visual Basic (version 5). The automatic image registration (AIR) routines freely available from Dr. Roger P. Woods, UCLA, (USA) were used in this software. This software could be easily implemented and was easy to use for image processing suitable for radiotherapy planning systems.

Algorithms↗
PubMed2004

Epilepsy with focal cerebral calcification: role of magnetization transfer MR imaging.

BACKGROUND: Some patients with focal cerebral calcification (FCC) have no seizure or a benign course of epilepsy, whilst others with a similar lesion have uncontrolled epilepsy. AIMS: To look for perilesional hyperintensity, presumed to be indicative of gliosis, around FCC on magnetization transfer (MT) MRI and to correlate seizure outcome with its presence. SETTING AND DESIGN: Case control study. MATERIAL AND METHODS: Fifty-one patients with epilepsy and 30 controls with single calcified cerebral lesion on CT were studied. Clinical and treatment details were noted. EEG and T1, T2, MT and contrast enhanced MRI were done. STATISTICAL ANALYSIS USED: Student's t test. RESULTS: On MT MRI, perilesional gliosis was seen around the focal calcified lesion in 17 (33.3%) patients. None of the controls had perilesional gliosis. The mean monthly seizure frequency was significantly higher in the 17 patients having perilesional gliosis (2.63+1.15) as compared to the 34 patients without it (0.59+0.63; P= 0.0014). Perilesional gliosis was seen in 8 out of 11 (72.7%) patients who were on 2 AEDs and in all 5 (100%) patients who were on 3 or more AEDs. It was present only in 4 (11.4%) out of 35 patients who were on one AED. CONCLUSION: Gliosis around a cerebral calcified lesion as seen on T1 weighted MT MRI indicates poor seizure control.

Adolescent↗
PubMed2004

Neurocysticercosis in clinically suspected and MRI proven cases: evidence of sub-optimal antibody response.

Neurocysticercosis (NCC) has a worldwide distribution mainly in the developing countries like India. The study was done to find the seroprevalence of anti-cysticercus antibodies in clinically suspected and MRI proven cases and to corroborate the serological findings with radiological findings (MRI). A hospital based study among 204 suspected patients during January, 1996 to August, 2001 showed that 77 (32.2%, M:F = 2.2:1) had serological evidence of NCC. Of the total 189 sera, tested at 1:100 dilution 68 (35.9%) and of the total 50 CSF, tested at 1:5 dilution 9 (18%) were positive for anti-cysticercus IgG antibodies. In 35 cases where both were tested 13 sera (37.1%), 9 CSF (25.7%) and in 7 (20%) both sera and CSF were positive. In CSF from 62 patients with tubercular meningitis (disease control) 2 (3.2%) samples whereas in sera of 60 normal blood donors (normal control) 7 (11.7%) samples had anti-cysticercus IgG antibodies. In 33 MRI-positive cases, anti-cysticercus antibodies were seen in 15 (45.4%) patients. Antibodies were seen in 6 of 14 (42.8%) cases with single cortical cyst, 4 of 11 (36.3%) with 2-3 cysts and in 5 of 8 (62.5%) with multiple cysts. Alternatively, 18 of 33 (54.5%) MRI positive cases lacked anti-cysticercus antibodies. Six MRI negative cases were found to be seropositive and were treated successfully. Hence, immune response was sub-optimal even in MRI positive cases and conversely, few MRI negative cases were seropositive. Since positive response with MRI or serology depends on the stage of the disease, therefore both tests should be done together to confirm or to rule out NCC.

Adolescent↗
PubMed2003

Detection of heavy metal ions using protein-functionalized microcantilever sensors.

Microcantilevers functionalized with metal-binding protein, AgNt84-6, are demonstrated to be sensors for the detection of heavy metal ions like Hg(2+) and Zn(2+). AgNt84-6, a protein that has the ability to bind multiple atoms of Ni(2+), Zn(2+), Co(2+), Cu(2+), Cd(2+) and Hg(2+) was attached to the gold-coated side of silicon nitride cantilevers via linker groups. Upon exposure to 0.1 mM HgCl(2) and 0.1 mM ZnCl(2) solutions, the microcantilevers underwent bending corresponding to an expanding gold side. Exposure to a 0.1 mM solution of MnCl(2) solution did not result in a similar bending indicating a weak or no interaction of Mn(2+) ions with the AgNt84-6 protein. The microcantilever bending data were consistent with data from electrophoresis carried out on SDS-PAGE gels containing metal ions that showed protein interaction with Zn(2+) ions but not with Mn(2+) ions. Thus, we demonstrate that microcantilever bending can be used to discriminate between metal ions that bind and do not bind to AgNt84-6 protein in real time.

Biosensing Techniques↗
PubMed2003

Brain abscesses: etiologic categorization with in vivo proton MR spectroscopy.

PURPOSE: To compare the metabolite patterns observed at in vivo proton magnetic resonance (MR) spectroscopy of brain abscesses in patients for whom bacteriologic information was obtained from cultures and to categorize the MR spectral patterns with respect to the underlying etiologic agents. MATERIALS AND METHODS: MR imaging and in vivo single-voxel proton MR spectroscopic data obtained from 75 patients with brain abscesses were retrospectively analyzed. Ex vivo spectroscopic experiments with the pus from 45 of these patients also were performed, and the data were further categorized on the basis of bacteriologic information. Quantification of various metabolites and metabolite ratios and statistical analyses of lactate and lactate/amino acid (AA) ratio levels were performed by using one-way analysis of variance. RESULTS: On the basis of in vivo proton MR spectroscopic and bacteriologic analysis findings, data were classified into three categories: Group 1 data showed resonances of lactate, AAs, and acetate, with or without succinate at proton MR spectroscopy; cultures for this group showed obligate anaerobes or a mixture of obligate and facultative anaerobes. The metabolite patterns in the group 2 and group 3 data were similar to the pattern of the group 1 data, with the exception that acetate and succinate resonances were absent. Culture was positive for either obligate aerobes or facultative anaerobes in group 2 and was sterile in group 3. At analysis of variance, in vivo data showed significant differences in lactate/AA ratios (P =.008), and ex vivo data showed significant differences in lactate levels (P =.001) among the three groups. CONCLUSION: It is possible to differentiate anaerobic from aerobic or sterile brain abscesses on the basis of metabolite patterns observed at in vivo proton MR spectroscopy. This information may be useful in facilitating prompt and appropriate treatment of patients with these abscesses.

Acetates↗
PubMed2003

Ventriculostomy in a tumor involving the third ventricular floor.

Recently, endoscopic management has gotten preference over open surgical treatment in selected cases of intraventricular tumors. Endoscopic third ventriculostomy (ETV) appears unfeasible when tumors extend to the third ventricular floor region due to the risk of perforators and injury to the basilar artery. We report the case of a 12-year-old male with symptoms of acute, chronic, raised intracranial pressure. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a posterior third ventricular tumor involving the aqueductal and floor regions. The ETV was done after clearing the floor by partial tumor resection, keeping the dorsum sellae as the major anatomical landmark. The patient improved satisfactorily and was given adjuvant radiotherapy, and the need for an external shunt was completely eliminated. We conclude that ETV appears worth trying, even in third ventricular tumors involving the floor region if they can be cleared from the tumor keeping the dorsum sellae as the major anatomical landmark.

Cerebral Aqueduct↗
PubMed2003

MR demonstration of brain abscess rupture into the subarachnoid space and its possible implication in management.

BACKGROUND: Rupture of brain abscess into the subarachnoid space as a cause of meningitis is rare. Early diagnosis improves the outcome. There is no previous report of MR demonstration of rupture of brain abscess into the subarachnoid space. CASE DESCRIPTION: Two young adults with chronic suppurative otitis media presenting with signs of increased intracranial pressure and meningeal irritation underwent magnetic resonance imaging, which showed brain abscess with evidence of rupture into the subarachnoid space and meningitis. This helped in early diagnosis and aggressive management. CONCLUSION: In cases of brain abscess where meningitis is suspected clinically, documentation of rupture of the abscess into the subarachnoid space will help in avoiding cerebrospinal fluid (CSF) examination that may be disastrous in these patients who already have increased intracranial pressure.

Adolescent↗
PubMed2003

Magnetization transfer and T2 quantitation in normal appearing cortical gray matter and white matter adjacent to focal abnormality in patients with traumatic brain injury.

Traumatic brain injury (TBI) is one of the commonest causes of morbidity and mortality in the developed countries with posttraumatic epilepsy and functional disability being its major sequelae. The purpose of this study was to test the hypothesis whether the normal appearing adjacent gray and white matter regions on T2 and T1 weighted magnetization transfer (MT) weighted images show any abnormality on quantitative imaging in patients with TBI. A total of 51 patients with TBI and 10 normal subjects were included in this study. There were significant differences in T2 and MT ratio values of T2 weighted and T1 weighted MT normal appearing gray matter regions adjacent to focal image abnormality compared to normal gray matter regions in the normal individuals as corresponding contralateral regions of the TBI patient's group (p < 0.05). However the adjoining normal appearing white matter quantitative values did not show any significant change compared to the corresponding contralateral normal white matter values. We conclude that quantitative T2 and MT ratio values provide additional abnormality in patients with TBI that is not discernable on conventional T2 weighted and T1 weighted MT imaging especially in gray matter. This additional information may be of value in overall management of these patients with TBI.

Adolescent↗
PubMed2003

Expression of the Photorhabdus luminescens lux genes (luxA, B, C, D, and E) in Saccharomyces cerevisiae.

The luxA, B, C, D, and E genes from Photorhabdus luminescens were cloned and functionally expressed in Saccharomyces cerevisiae to construct a bacterial lux-based yeast bioreporter capable of autonomous bioluminescence emission. The bioreporter was engineered using a series of pBEVY yeast expression vectors that allowed for bi-directional constitutive or inducible expression of the individual luxA, B, C, and E genes. The luxD gene, encoding the acyl-ACP transferase that ultimately supplies the requisite aldehyde substrate for the bioluminescent reaction, was fused to a yeast internal ribosomal entry site (IRES) sequence to ensure high bi-cistronic expression. Although self-generation of bioluminescence was achieved by the bioreporter, the signal was relatively weak and decayed rapidly. To overcome this instability, a flavin oxidoreductase gene (frp) from Vibrio harveyi was co-expressed to provide sufficient concentrations of the FMNH(2) co-factor required for the bioluminescent reaction. Expression of frp with the lux genes not only stabilized but also enhanced bioluminescence to levels approaching 9.0x10(5) times above background.

Acyltransferases↗