Retrotransposons: central players in the structure, evolution and function of plant genomes.
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Biological Evolution↗
Biomedical subjects
A Kumar
Publications and source records attributed to A Kumar.
Genome-wide mutant collections: toolboxes for functional genomics.
The sequencing of entire genomes has led to the identification of many genes. A future challenge will be to determine the function of all of the genes of an organism. One of the best ways to ascertain function is to disrupt genes and determine the phenotype of the resulting organism. Novel large-scale approaches for generating gene disruptions and analyzing the resulting phenotype are underway in the budding yeast Saccharomyces cerevisiae and other organisms including flies, Mycoplasma, worms, plants and mice. These approaches and mutant collections will be extremely valuable to the scientific community and will dramatically alter the manner in which science is performed in the future.
Animals↗
Temperature dependent luminescence characteristics of Sm3+-doped silicate glass.
We report here on the optical characterisation of Sm3+ (5 wt%): SiO2 + Al2O3 + Li2O + Na2O + MgO glass from the measurements of optical absorption spectra (at 300 K), total luminescence spectra (10-300 K) and fluorescence lifetimes (10-300 K) of the prominent emission transitions of the Sm3+ ions. Besides its spectral properties, physical and nonlinearity characterising property parameters have also been computed to understand the optical dispersive power of this glass. By the application of Judd-Ofelt parameters (omega(lambda)) of the measured absorption spectrum, the radiative transition probability factors (A) and stimulated emission cross-section (sigma(p)E) of the observed fluorescent levels have been analysed. Both emission intensity and measured lifetimes of the prominent luminescent transition (4G(5/2) --> 6H(7/2)) concerning Sm3+-glass has been showing a descending trend with the rise in temperature with N2-laser (337.1 nm) as the source of excitation.
Glass↗
Candida antartica lipase B catalyzed polycaprolactone synthesis: effects of organic media and temperature.
Engineering of the reaction medium and study of an expanded range of reaction temperatures were carried out in an effort to positively influence the outcome of Novozyme-435 (immobilized Lipase B from Candida antarctica) catalyzed epsilon-CL polymerizations. A series of solvents including acetonitrile, dioxane, tetrahydrofuran, chloroform, butyl ether, isopropyl ether, isooctane, and toluene (log P from -1.1 to 4.5) were evaluated at 70 degrees C. Statistically (ANOVA), two significant regions were observed. Solvents having log P values from -1.1 to 0.49 showed low propagation rates (< or = 30% epsilon-CL conversion in 4 h) and gave products of short chain length (Mn < or = 5200 g/mol). In contrast, solvents with log P values from 1.9 to 4.5 showed enhanced propagation rates and afforded polymers of higher molecular weight (Mn = 11,500-17,000 g/mol). Toluene, a preferred solvent for this work, was studied at epsilon-CL to toluene (wt/vol) ratios from 1:1 to 10:1. The ratio 1:2 was selected since, for polymerizations at 70 degrees C, 0.3 mL of epsilon-CL and 4 h, gave high monomer conversions and Mn values (approximately 85% and approximately 17,000 g/mol, respectively). Increasing the scale of the reaction from 0.3 to 10 mL of CL resulted in a similar isolated product yield, but the Mn increased from 17,200 to 44,800 g/mol. Toluene appeared to help stabilize Novozyme-435 so that lipase-catalyzed polymerizations could be conducted effectively at 90 degrees C. For example, within only 2 h at 90 degrees C (toluene-d8 to epsilon-CL, 5:1, approximately 1% protein), the % monomer conversion reached approximately 90%. Also, the controlled character of these polymerizations as a function of reaction temperature was evaluated.
Candida↗
Simulation of robotic courier deliveries in hospital distribution services.
Flexible automation in the form of robotic couriers holds the potential for decreasing operating costs while improving delivery performance in hospital delivery systems. This paper discusses the use of simulation modeling to analyze the costs, benefits, and performance tradeoffs related to the installation and use of a fleet of robotic couriers within hospital facilities. The results of this study enable a better understanding of the delivery and transportation requirements of hospitals. Specifically, we examine how a fleet of robotic couriers can meet the performance requirements of the system while maintaining cost efficiency. We show that for clinical laboratory and pharmaceutical deliveries a fleet of six robotic couriers can achieve significant performance gains in terms of turn-around time and delivery variability over the current system of three human couriers per shift or 13 FTEs. Specifically, the simulation results indicate that using robotic couriers to perform both clinical laboratory and pharmaceutical deliveries would result in a 34% decrease in turn-around time, and a 38% decrease in delivery variability. In addition, a break-even analysis indicated that a positive net present value occurs if nine or more FTEs are eliminated with a resulting ROI of 12%. This analysis demonstrates that simulation can be a valuable tool for examining health care distribution services and indicates that a robotic courier system may yield significant benefits over a traditional courier system in this application.
Computer Simulation↗
Comparative evaluation of early vs. deferred vitrectomy in Eales' disease.
METHODS: 40 cases of vitreous haemorrhage secondary to Eales' disease were taken up for vitrectomy. Depending upon duration of vitreous haemorrhage patients were divided into two groups: Group I (20 eyes) - early vitrectomy group with duration between 3-6 months; Group II (20 eyes) - deferred vitrectomy group with duration of more than 6 months. All patients were followed up for a minimum period of 3 months following vitrectomy. RESULTS: Eyes in Group I showing a preoperative ultrasonic picture of complete posterior vitreous detachment, less mobility of organised vitreous haemorrhage and mid vitreous organisation on kinetic echography achieved a final visual acuity of 6/9 or better in 13 (65%) eyes as compared to 4 (20%) eyes in Group II (p<0.01). Poor visual outcome in the deferred group was secondary to cystoid macular oedema, macular scar, macular pucker formation and macular degeneration. CONCLUSION: Improved visual outcome in the early vitrectomy group was probably because the haemorrhagic blood and its toxic products had less time to damage the macula, a lesser incidence of macular traction and cystoid macular oedema.
Humans↗
Neuropathogenesis of chimeric simian human immunodeficiency virus infection in rhesus macaques.
Comparative studies were performed to determine the neuropathogenesis of infection in macaques with simian human immunodeficiency virus (SHIV)89.6P and SHIV(KU). Both viruses utilize the CD4 receptor and CXCR4 co-receptor. However, in addition, SHIV89.6P uses the CCR5 co-receptor. Both agents are dual tropic for CD4+ T cells and blood-derived macrophages of rhesus macaques. Following inoculation into macaques, both caused rapid elimination of CD4+ T cells but they varied greatly in mechanisms of neuropathogenesis. Two animals infected with SHIV89.6P developed typical lentiviral encephalitis in which multinucleated giant cell formation, nodular accumulations of microglial cells, activated macrophages and astrocytes, and perivascular accumulations of mononuclear cells were present in the brain. Many of the macrophages in these lesions contained viral RNA. Three macaques infected with SHIV(KU) and killed on days 6, 11 and 18, respectively, developed a slowly progressive infection in the CNS but macrophages were not productively infected and there were no pathological changes in the brain. Two other animals infected with this virus and killed several months later showed minimal infection in the brain even though one of the two developed encephalitis of unknown etiology. The basic difference in the mechanisms of neuropathogenesis by the two viruses may be related to co-receptor usage. SHIV89.6P, in utilizing the CCR5 co-receptor, caused neuropathogenic effects that are similar to other neurovirulent primate lentiviruses.
AIDS Dementia Complex↗
Evoked potential monitoring in anaesthesia and analgesia.
Electrophysiological monitoring of selected neural pathways of the brain, brainstem, spinal cord and peripheral nervous system has become mandatory in some surgery of the nervous system where preventable neural injury can occur. Evoked potentials are relatively simple methods of testing the integrity of various aspects of the nervous system. This review covers the variety of evoked potentials that can be monitored and outlines the principles of their measurement. Their use in specific situations and how factors such as anaesthesia might affect them is presented.
Analgesics↗
A device for cricothyrotomy and retrograde intubation.
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Humans↗
Long-term results of arteriovenous fistulas using transposed autologous basilic vein.
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Arteriovenous Fistula↗
Histological assessment of vertebral bone in a Down's syndrome adult with osteoporosis.
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Bone and Bones↗
Generation of mononucleate cells from post-mitotic myotubes proceeds in the absence of cell cycle progression.
The remarkable regenerative ability of adult urodele amphibians depends in part of the plasticity of differentiated cells at the site of injury. Limb regeneration proceeds by formation of a mesenchymal growth zone or blastema under the wound epidermis at the end of the stump. Previous work has shown that when cultured post-mitotic newt myotubes are introduced into the blastema, they re-enter the cell cycle and undergo conversion to mononucleate cells which divide and contribute to the regenerate [11, 13]. In order to investigate the interdependence of these two aspects of plasticity, we have blocked cell cycle progression of the myotubes either by X-irradiation or by transfection of the CDK4/6 inhibitor p16. In each case, the efficacy of the block was evaluated in culture after activation of S phase re-entry by serum stimulation. The experimental myotubes were implanted into limb blastemas along with a differentially labelled control population of myotubes containing an equivalent number of nuclei. X-irradiated myotubes gave rise to mononucleate cells in the limb blastema, and the progeny were blocked in respect of S phase entry. Comparable results were obtained with the p16-expressing myotubes. We conclude that progression through S or M phase is not required for generation of mononucleate cells and suggest that such cells may arise by budding from the muscle syncytium.
Animals↗
Intravitreal pefloxacin therapy in postoperative endophthalmitis.
PURPOSE: To study the efficacy of intravitreal pefloxacin in the management of suspected bacterial endophthalmitis. METHODS: Twenty eyes with suspected postoperative bacterial endophthalmitis were given an intravitreal injection of pefloxacin (200 microg in 0.1 mL). If required the injection was repeated after 24 h. The main parameters evaluated were visual acuity, response to intravitreal therapy and any complications due to intravitreal pefloxacin. RESULTS: Fourteen eyes (70%) responded to intravitreal pefloxacin therapy alone, while an additional pars plana vitrectomy was required in six eyes (30%). Nineteen eyes retained a visual acuity of 6/60 or better at 3 months after the initiation of therapy. A retinal detachment developed in one of the eyes which received intravitreal therapy. CONCLUSIONS: Intravitreal pefloxacin may be a useful aternative therapy in bacteria endophthalmitis.
Aged↗
Aluminum increases levels of beta-amyloid and ubiquitin in neuroblastoma but not in glioma cells.
Several epidemiological studies suggest the involvement of aluminum (Al) in the pathogenesis of Alzheimer's disease (AD). There is an increase in the levels of Abeta and ubiquitin in the pathological lesions of AD. Therefore, we have investigated whether aluminum (Al) treatment alters the levels of Abeta and ubiquitin in murine neuroblastoma (NBP2) and rat glioma (C-6) cell cultures. At a low concentration (10 microM), aluminum sulfate stimulated the level of immunoreactive Abeta and ubiquitin in NBP2 cells without changing the levels of the amyloid precursor protein (APP). However, at higher concentrations (100 and 500 microM), aluminum failed to elicit any significant effect on beta-amyloid, whereas ubiquitin levels continued to increase. No changes in the Abeta and ubiquitin content were found in the C-6 glioma cells following treatment with Al at any of the concentrations tested. Exposure of cells to aluminum salts did not alter the rate of proliferation in either of the two cell lines. These data suggest that one of the mechanisms by which Al may play a role in AD is by promoting the formation of Abeta and ubiquitin in neurons.
Alum Compounds↗
Sestamibi scan-directed unilateral neck exploration for primary hyperparathyroidism due to a solitary adenoma.
AIM: To evaluate the accuracy of Tc-99m sestamibi scintography in pre-operative localization of a single parathyroid adenoma and to determine if neck exploration can be limited to the side of the adenoma. METHODS: Over a period of 4 years, 30 patients with primary hyperparathyroid disease underwent surgical treatment in the form of unilateral neck exploration after localization by Tc-99m sestamibi scintigraphy. The scan findings were interpreted by one radiologist with a special interest in parathyroid imaging and the operative findings were correlated with scan findings. RESULTS: Tc-99 sestamibi scan localized a single parathyroid adenoma in 29 patients. There was doubtful uptake of isotope in one patient. Unilateral cervical exploration confirmed isotope scan findings in 29 patients with a positive scan, and these were subsequently proven by histology. In the patient with doubtful sestamibi scan, bilateral neck exploration was undertaken and three enlarged glands were excised. All the three glands were reported to be abnormal, consistent with either adenomas or hyperplasia. All the patients were normocalcaemic after 6 months follow-up. CONCLUSIONS: Our results demonstrate that Tc-99m sestamibi scintigraphy is highly accurate in pre-operative localization of a single parathyroid adenoma when performed by an experienced radiologist. Unilateral cervical exploration, as directed by a positive Tc-99m sestamibi scintigram, seems to be a logical approach for the patients with primary hyperparathyroid disease due to solitary adenoma.
Adenoma↗
Increased type-IV collagenase (MMP-2 and MMP-9) activity following preoperative radiotherapy in rectal cancer.
The aim of this study was to investigate the effect of preoperative high-dose radiotherapy (25 Gy in 5 fractions over 5 days) on the type-IV collagenase protein profile, in patients with resectable rectal cancer, by gelatin zymography. Biopsy samples of tumour and distant normal mucosa from 12 patients with resectable rectal cancer were obtained pre- and post-radiotherapy. Expression of type-IV collagenases (both pro- and active forms) was studied using gelatin zymography. Enzyme levels were normalized for total protein content of each sample. Rectal cancer specimens expressed both pro (72 kDa) and active (62 kDa) forms of MMP-2 but only the pro form of MMP-9 (92 kDa). Normal mucosa showed expression of the pro forms of MMP-2 and MMP-9 while no active form of either enzyme was detected in any of the samples. A significant three- to fourfold increase (P < 0.01) of active matrix metalloproteinases (MMP)-2 (62 kDa) was seen in malignant rectal mucosa after radiotherapy. The effect of radiotherapy also led to a twofold increase (P = 0.047) of pro MMP-2 (72 kDa) and a two- to threefold increase (P = 0.03) of the precursor form of MMP-9 (92 kDa). In contrast, in normal mucosa expression of the precursor form of MMP-9 (92 kDa) did not change after radiation, and no significant effect on the levels of pro MMP-2 (72 kDa) was observed. Preoperative high-dose radiotherapy leads to an increase in activity of type-IV collagenases in patients with resectable rectal cancer. Type-IV collagenase inhibition may be a useful therapeutic adjunct to radiotherapy in rectal cancer.
Adenocarcinoma↗
Newer substituted beta-aminonaphthalenes as potent anti-inflammatory agents.
beta-[2-(3'-Chloro-2'-oxo-4'-substituted aryl-1'-azetidinyl)-thiazol-4- yl]aminonaphthalenes 13-17 and beta-[2-(1',3'-disubstitutedphenyl-formazan-4'-yl)-thiazol-4-yl] aminonaphthalenes 8-12 were synthesized from beta-(2-arylideneamino-thiazol-4-yl)aminonaphthalenes 3-7 by diazotisation and by cycloaddition with monochloroacetyl chloride, respectively, on the azomethine group of the compounds 3-7. The newly synthesized compounds showed potent anti-inflammatory and analgesic activities and were less ulcerogenic than phenylbutazone.
2-Naphthylamine↗
Dynamic control and conventional strength ratios of the quadriceps and hamstrings in subjects with anterior cruciate ligament deficiency.
The hamstrings:quadriceps muscle strength ratio has been used as an indicator of normal balance between the knee flexors and extensors. A more functional approach to this strength ratio would be to compare opposite muscle actions of antagonistic muscle groups. The dynamic strength control ratio (DSCR) should give a more appropriate measure relating to knee function. There is a lack of normative data relating to DSCR for anterior cruciate ligament (ACL) deficient subjects. Effects of ACL deficiency on isokinetic peak torque for eccentric and concentric muscle actions of the quadriceps and hamstrings, in conjunction with isometric peak torque, were examined in 10 patients awaiting reconstructive surgery (male = 8, female = 2 ; age = 32.8 +/- 8.3 years; height = 1.77 +/- 0.08 m; mass = 72.1 +/- 12.5 kg). These variables were assessed using an isokinetic dynamometer. The results were considered in terms of the conventional ratio and DSCR. Anterior tibial drawer was measured using a knee ligament arthrometer to confirm clinical diagnosis of ACL rupture. The isokinetic peak torque data analysed were for angular velocities of 1.05 rad s(-1) (60 degrees s(-1)). Significant strength deficits were apparent between normal and injured sides for: concentric isokinetic quadriceps action (p < 0.05); isometric quadriceps action at 70 degrees of knee flexion (p < 0.05); isometric quadriceps action at 40 degrees of knee flexion (p<0.01); eccentric isokinetic hamstrings action (p < 0.05). With bilateral comparison, the conventional strength ratios showed no significant difference, as did the DSCR. The bilateral comparison of isometric strength ratios revealed significant losses in quadriceps strength for the injured side (p < 0.05) but no significant losses in hamstring strength (p > 0.05). Thus, differences can be seen in conventional ratios and DSCR for ACL-deficient subjects. This is an area of clinical interest with the increasing frequency of ACL reconstruction using hamstrings tendons.
Adult↗