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Biomedical subjects

K Saha

Publications and source records attributed to K Saha.

At least 19 recordsLinked to original sources
PubMed2006

'Fast-track' cataract services and diagnostic and treatment centre: impact on surgical training.

AIMS: To evaluate the impact of 'Action on Cataracts' and the development of Diagnostic and Treatment Centre (DTC) on cataract surgery training in the Central Manchester and Manchester Children's University Hospital's Trust. METHODS: We compared all cataract extractions undertaken from April to September 2005 with the same 6-month time period over the preceding 5 years. Surgery was performed on one of four types of lists: Manchester Royal Eye Hospital standard lists (MREH), Cataract Services list, Waiting List Initiative list (WLI), and Diagnostic and Treatment Centre list (DTC). Surgeons were identified by their specific codes and divided into grades. RESULTS: The total number of cataract operations undertaken on the standard MREH lists has declined significantly over the years (P<0.001 chi(2) test for trend). The number of cataract operations performed by both Specialist Registrars (SpRs) and Senior House Officers (SHOs) demonstrated a statistically significant decline over the years (P<0.001 for both cases, chi(2) test for trend), with the SHOs number dropping dramatically over the last 2 years. When comparing the number of operations performed by junior SpRs and senior SpRs, shift in the balance can be seen towards the senior surgeons. The proportion of operations performed by junior SpRs declined from 50% in 2000 to 28.2% in 2005. CONCLUSION: Recent changes in cataract care provision have had a significant impact on training. Our results document for the first time that both higher and basic surgical trainees were affected. Future care of our patients could be comprised owing to lack of training.

Cataract↗
PubMed2006

Ocular hazards of the colors used during the festival-of-colors (Holi) in India--malachite green toxicity.

The objective of this study was to evaluate the nature of the colors used and their toxicity to the eye upon exposure to them during celebration of Holi (our festival-of-colors). Color powders and formulations were procured at random in and around Delhi during the festival. The green/bluish-green colors reported with the higher incidence of ocular toxicity were subjected for further evaluation. Eyewash fluid collected from the patients exposed to the colors was also subjected for analysis. This study was further extended to evaluate the corneal penetration of malachite green using goat cornea in perfusion chamber. In 16/18 color samples collected, malachite green or 4-[(4-dimethylaminophenyl)-phenyl-methyl]-N,N-dimethyl-aniline was detected at different concentrations. In the eyewash fluid of four patients, HPLC estimation confirmed the presence of malachite green at concentrations of 1.3, 0.18, 3.5 and 5.4 microg in 250 ml which was responsible for its reported toxicity. The in vitrotrans-corneal penetration studies did not show any detectable amount of malachite green in effluent fluid-in vitro tissue retention studies revealed that increasing the contact time increases tissue concentration. After 2 min of exposure, the tissue concentration was significantly higher. To conclude, malachite green was extensively used in our festival of Holi and has caused severe ocular irritation with epithelial defect upon exposure, though it did not penetrate through the cornea-further in vitro and in vivo studies are required on colors used in Holi.

Animals↗
PubMed2005

Ocular syphilis: the new epidemic.

AIM: To present the clinical presentation, diagnosis, and management of syphilitic uveitis in the context of an epidemic of syphilis in the UK. METHOD: Retrospective clinical case series. RESULTS: Six new cases of syphilitic uveitis presented to the Manchester Uveitis Clinic in 2004, after a 15-fold increase in the incidence of syphilis in the UK, including 615 cases in Greater Manchester in the 5 years to 2004. Four cases had secondary syphilis, two had latent disease, two had no rash, and two were HIV positive. Ocular involvement included anterior or panuveitis, retinitis, retinal vasculitis, and papillitis. All resolved on treatment including intramuscular procaine penicillin G with oral probenecid. CONCLUSIONS: Syphilis is much more common recently and syphilitic uveitis should be considered in all patients with rash and/or headache, where there is retinitis and/or retinal vasculitis, or in any uveitis of uncertain origin. Treatment is that of neurosyphilis.

Adult↗
PubMed2005

Heavy metals in water of the rivers Hooghly and Haldi at Haldia and their impact on fish.

The paper deals with the measurement of five heavy metals viz., Cd, Cu, Mn, Pb and Zn in water of the rivers Hooghly and Haldi at Haldia during June 1999 to October 2002. The industrial effluent out fall (OF) at Patikhali, Haldia was also taken as sampling site along with above out fall (AOF) and below out fall (BOF) sites. Most of the metals exhibited their least concentration at the sampling site above the Haldia industrial area of river Hooghly. The average concentrations of the studied metals were Cd 2-14, Cu 5-19, Mn 8-88, Pb 17-41 and Zn 22-37 microg l(-1). Comparison of the data with the Criterion Continuous Concentration (CCC) of USA revealed that Cd, Cu and Pb were the pollutants present at alarming level to disturb the aquatic life process in the zone. The effect was found to reflect on the tissue level aberrations in the residential fishes. The other two metals viz., Mn and Zn were probably less harmful to the aquatic ecosystem. In India, necessity is felt to develop the CCC values, which will be more appropriate for protection of aquatic environment than comparing with drinking water standards.

Animals↗
PubMed2004

Evaluation of antioxidant and nitric oxide inhibitory activities of selected Malaysian medicinal plants.

Methanol extracts of seven Malaysian medicinal plants were screened for antioxidant and nitric oxide inhibitory activities. Antioxidant activity was measured by using FTC, TBA and DPPH free radical scavenging methods and Griess assay was used for the measurement of nitric oxide inhibition in lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma)-treated RAW 264.7 cells. All the extracts showed strong antioxidant activity comparable to or higher than that of alpha-tocopherol, BHT and quercetin in FTC and TBA methods. The extracts from Leea indica and Spermacoce articularis showed strong DPPH free radical scavenging activity comparable with quercetin, BHT and Vit C. Spermacoce exilis showed only moderate activity but other species were weak as compared to the standards. In the Griess assay Lasianthus oblongus, Chasalia chartacea, Hedyotis verticillata, Spermacoce articularis and Leea indica showed strong inhibitory activity on nitric oxide production in LPS and IFN-gamma-induced RAW 264.7 cells. Extracts from Psychotria rostrata and Spermacoce exilis also inhibited NO production but this was due to their cytotoxic effects upon cells during culture.

Animals↗
PubMed2003

Sensitivity of the acoustic waveguide biosensor to protein binding as a function of the waveguide properties.

The aim of this work is to study the effect of operating frequency, piezoelectric substrate and waveguide layer thickness on the sensitivity of the acoustic waveguide sensor during the specific binding of an antibody by a protein. Shear horizontal (SH) wave devices consisting of (a) a LiTaO3 substrate operating at 104 MHz, (b) a quartz substrate operating at 108 MHz and (c) a quartz substrate operating at 155 MHz were coated with a photoresist polymer layer in order to produce acoustic waveguide devices supporting a Love wave. The effect of the thickness of the polymer layer on the Love wave was assessed by measuring the amplitude and phase of the wave before and after coating. The sensitivity of the above three biosensors was compared during the detection of the specific binding of different concentrations of Immunoglobulin G in the range of 0.7-667 nM to a protein A modified surface. Results indicate that the thickness of the polymer guiding layer is critical for obtaining the maximum sensitivity for a given geometry but a trade-off has to be made between the theoretically determined optimum thickness for waveguiding and the device insertion loss. It was also found that increasing the frequency of operation results in a further increase in the device sensitivity to protein detection.

Acoustics↗
PubMed2003

Comparative study of IgG binding to proteins G and A: nonequilibrium kinetic and binding constant determination with the acoustic waveguide device.

The aim of this work was to measure and compare the binding constants of antibody immunoglobulin G (IgG) to bacterial cell wall proteins, streptococcal protein G and Staphylococcus aureus protein A, using an acoustic wave sensor. Devices, which used shear-horizontal acoustic waves propagating in a waveguide configuration at 108 and 155 MHz, were employed in the detection of apparent IgG binding constants at the solid-liquid interface in the range of 6.7-667 nM IgG. Real-time data during IgG-protein G and IgG-protein A binding yielded apparent association constants of 3.29 x 10(4) and 8.02 x 10(3) M(-1) s(-1) leading to equilibrium constants of 1.13 x 10(8) and 2.90 x 10(7) M(-1), respectively. The measured apparent rate constants are consistent with literature reports of higher affinity of protein G for IgG. Furthermore, protein binding through the Fc region of IgG is suggested to occur below 333 nM, while different mechanisms are suggested to occur above 333 nM. For the first time, nonequilibrium studies of IgG-protein G and A binding at a solid-liquid interface has yielded valuable quantitative kinetic information about binding mechanisms. The promise of this detection method is shown by providing quick determination of binding constants with low sample volumes.

Acoustics↗
PubMed2003

Ultra-structural observations on the lymphoid organs of the freshwater catfish, Clarias batrachus (Linnaeus).

Light microscopic and ultra-structural studies of the lymphoid tissues such as blood immunocytes, spleen and pronephros of the freshwater catfish, Clarias batrachus, were carried out. The peripheral blood showed nucleated erythrocytes, total leucocytic count (TLC) more than that observed in mammalian blood and leucocytes with morphological appearance similar to the mammalian white blood cells (WBCs). The spleen and pronephros showed presence of numerous lymphocytes, monocytes and nucleated red blood cells (RBCs) along with hemosiderin-containing macrophages. The morphology of lymphoid organs of the catfish has been discussed in light of the evolution of the immune system in this class of vertebrates.

Animals↗
PubMed2001

Evidence of productively infected CD8+ T cells in patients with AIDS: implications for HIV-1 pathogenesis.

CD8+ T lymphocytes play an important protective role against HIV infection. The onset of AIDS is associated with a decline in both the number of CD8+ T lymphocytes and anti-HIV cytotoxic activity in CD8+ T cells. The reason for this progressive failure of CD8+ T cells in HIV-1 infection remains unknown. Earlier reports have shown presence of viral DNA in CD8+ cells of HIV-1-infected patients; under some conditions, CD8+ T cells have been shown to express CD4 in vitro and can be susceptible to infection with HIV-1. However, whether CD8+ lymphocytes in vivo can be productively infected with HIV-1 remains unclear. In this study, we generated multiple CD8+ T-cell clones from two patients with AIDS. These clones were CD8+/CD3+ but did not express CD4. Several of these CD8+ clones from both patients were found to be endogenously infected with HIV-1 and spontaneously produced these viruses. CD8+ cell-produced HIV-1 was biologically competent because viruses produced by most of these clones could efficiently infect and replicate in peripheral blood lymphocytes from HIV-negative donors. In addition, some of these viruses were able to form syncytia in MT-2 cells indicating syncytium-inducing phenotype. Comparison of the sequences in V3 loop areas among different viruses showed changes in some of the clones from both patients. For the first time, this report provides direct evidence that mature CD8+ T cells can be productively infected with HIV-1 in patients with AIDS. Direct infection of CD8+ T lymphocytes may play a role in the eventual failure of these cells in HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Isolation of primary HIV-1 that target CD8+ T lymphocytes using CD8 as a receptor.

HIV-1 use CD4 receptors to infect their primary targets, CD4+ cells, whereas CD8+ cells have a protective role against HIV-1. We recently isolated HIV-1-producing CD8+ clones from two AIDS patients. Here we show that although HIV-1 produced by CD8+ cells maintained the ability to infect CD4+ cells, these viruses were able to infect CD8+ cells independent of CD4. Evidence indicates that these viruses used CD8 as a receptor to infect CD8+ cells. First, expression of CD8 was downmodulated after infection. Second, anti-CD8 antibodies blocked viral entry and replication in CD8+ cells. Finally, resistant cells became susceptible after expression of CD8. Although these viruses used CXCR4 to enter CD4+ cells, it seems that infection of CD8+ cells was independent of CXCR4 or CCR5 co-receptors. Novel changes were observed in envelope sequences of CD8-tropic viruses. These results provide initial evidence that HIV-1 can mutate to infect CD8+ cells using CD8 as a receptor.

Amino Acid Sequence↗
PubMed2001

Treatment of patients with thromboangiitis obliterans with cyclophosphamide.

This report describes a small, nonrandomized trial of cyclophosphamide in the treatment of patients with advanced thromboangiitis obliterans (TAO) with modest results. The rationale of the treatment was based on the immunopathogenesis of the disease, ie, autoimmune vasculitis of peripheral arteries. Twelve male patient volunteers with TAO were included for the trial. Diagnosis was based on the history of chronic smoking or tobacco chewing, clinical features of ischemia of peripheral vessels, radioarteriography showing arterial block, and characteristic histopathologic changes of affected arteries. Cyclophosphamide (400 mg) was given intravenously daily to the patients for 7 days followed by daily oral administration of 100 mg cyclophosphamide for another 7 weeks. Clinical conditions of the patients started to improve during the third week of the treatment and maximum benefit was noticed at the end of the treatment. There was significant decrease of intermittent claudication and twentyfold increase of claudication distance as well as relief of rest pain. Before starting treatment 6 patients had developed ulcers on their affected limbs; these healed completely in 2, partially healed in another 2, and showed no improvement in the remaining 2, who never stopped smoking. However, immunosuppressive therapy failed to show any improvement of arterial block, as evidenced by radioarteriography and any significant increase of skin temperature over the affected limbs. Nevertheless, histopathologic studies of biopsies taken from the diseased arteries after completion of therapy showed decreased influx of lymphocytes and plasma cells in the thrombi as well as in the arterial walls in comparison to the biopsies taken before the start of treatment. During the treatment the degree of immunosuppression was monitored by blood leukocyte and lymphocyte counts, which were kept between 4,000/mm3 and above 3,000/mm3 and not less than 500/mm3, respectively, indicating modest immunosuppression and no serious complications. All patients were followed up for 1 year. Only 2 patients, who resumed smoking, had relapse.

Administration, Oral↗
PubMed2000

A rapid and sensitive assay method for measuring amine oxidase based on hydrogen peroxide-titanium complex formation.

Hydrogenperoxide (H(2)O(2)) is an end product of diamine and polyamine oxidation by their respective oxidase enzymes. A new sensitive assay method is based on a H(2)O(2)-titanium (Ti) complex formation as an indicator of H(2)O(2) production due to polyamine oxidation. The orange-yellow coloured H(2)O(2)-Ti complex was measured at 410 nm in a Shimadzu spectrophotometer. The assay conditions for maximum diamine oxidase (DAO) and polyamine oxidase (PAO) as standardized here using the hypocotyl tissues of Vigna catjang Endl. cv Pusa Barsati consisted of pH 7.4 (40 mM potassium phosphate buffer), 3 mM substrate (putrescine or spermine), 37 degrees C incubation temperature and 30 min incubation time in the presence of catechol (10(-2) M) used as an inhibitor of both peroxidase and catalase activity. The method described here was significantly more sensitive than the starch-iodide method [T.A. Smith, Biochem. Biophys. Res. Commun. 41 (1970) 1452-1456], which could be improved further if measured under the same assay conditions as described for the H(2)O(2)-Ti method. Sensitivity of the present method was tested by assaying DAO/PAO activity in auxin treated hypocotyls of Vigna and comparing it with the starch-iodide method in two other plant samples.

Journal Article↗
PubMed2000

Dependence of CD8+ T-cell-mediated suppression of HIV type 1 on viral phenotypes and mediation of phenotype-dependent suppression by viral envelope gene and not by beta-chemokines.

CD8+ T-cell-mediated HIV-1 suppressive activity has been shown against a number of strains of HIV-1 and HIV-2. In this study using a semiquantitative assay, we showed that CD8+ T cells from seropositive subjects and herpes virus saimiri transformed CD8+ T-cell clones from HIV-1-infected subjects exhibited 5 to 100-fold higher suppressive activity against slow replicating nonsyncytia-inducing strains (Slow/NSI) as compared to fast replicating syncytia-inducing strains (Fast/SI) of HIV-1. Such differential suppressive activity was not due to beta-chemokines as evidenced by the lack of blocking activity of antibodies to RANTES, MIP-1beta, and MIP-1alpha on the antiviral activities of CD8+ T cells. Moreover, there was no correlation between the level of CD8+ T-cell suppression and the level of these beta-chemokines in culture supernatant. Results from the CD8+ T-cell-mediated suppressive activity against two molecular cloned virus ME1 (Slow/NSI), ME46 (Fast/SI), and their interstrain recombinants indicate that the envelope gene carries a major genetic determinant responsible for this phenotypic-dependent differential suppressive activity.

CD4-Positive T-Lymphocytes↗
PubMed2000

Unusual presentation of schwannoma.

Schwannomas are slow growing benign tumours arising from the nerve sheath. Two cases of schwannoma arising from the vagus nerve are presented here. One case was found in a 6-year-old boy and another one in a 30-year-old man. In the first case the tumour was detected on the left side of the neck just below the angle of the mandible, and in the second case it was found on the lower part of the right side of the neck. Histopathology confirmed the diagnosis as first one to be of Antoni-A type and the second one to be of Antoni-B type. Both the tumours were excised and on follow-up the patients were doing well.

Adult↗