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Biomedical subjects

A Ismail

Publications and source records attributed to A Ismail.

At least 19 recordsLinked to original sources
PubMed2006

The pathogenesis of post kala-azar dermal leishmaniasis from the field to the molecule: does ultraviolet light (UVB) radiation play a role?

Post kala-azar dermal leishmaniasis (PKDL) is a dermatosis caused by persistence of Leishmania donovani parasites in the skin following apparently successful treatment of visceral leishmaniasis. The distribution of PKDL lesions in Sudanese patients often mirrors the clothing habits of those affected. It is most severe in or confined to the sun-exposed parts of the skin. It is well established that elimination of Leishmania parasites requires activation of parasitised macrophages by a Th1 immune response and that the latter is depressed by ultraviolet light (UVB). In this paper, we hypothesized that UVB light might be a key player in the pathogenesis of PKDL. This paper links observations made in the field with immunological data that are compatible with this hypothesis. We therefore investigated patients with PKDL immunologically for a possible role of UVB exposure in the pathogenesis of this condition. We marshal evidence that the changes in the tissues are compatible with the effects of UVB light and it is probable that UVB appears to be a key factor in the pathogenesis of PKDL. Immunopathologically the lesions were characterized by an influx of various inflammatory cells. The number of CD1a (Langerhans' cells) was decreased, they lost their dendrites, their HLA-DR and B7-1 expression was down regulated while B7-2 was expressed. Others have shown that Langerhans' cells with these features result from UVB exposure and that such cells are unable to present antigen to Th1 cells while retaining the capacity to present antigen to Th2 cells. Various cytokines known to be induced by UVB radiation could be demonstrated in PKDL lesions. Of these IL-10, TGF-beta, IL-12, IL-4 and TNF-alpha were found in different quantities. The Th-1 cytokine IFN-gamma was constantly present. The tissue origin of the Th-1 cells in PKDL is unknown. We believe that the antagonistic action of the different cytokines is the cause of the inflammation and chronicity of PKDL.

Cytokines↗
PubMed2006

[Percutaneous mitral commisurotomy in patients aged 60 years and more].

Of 745 patients treated by balloon mitral commissurotomy (BMC) between February 1988 and December 2002, 45 were > or = 60-years old. Immediate and late outcomes in this group (group 1) were compared with those in the patients aged < 60-years (group 2). Baseline hemodynamic parameters were comparable in the two groups. Mitral surface area and hemodynamic parameters improved significantly after BMC in group 1: mean left atrial pressure fell from 18.76 +/- 6.18 to 10.65 +/- 4.38 mmHg (P < 0.001), mean transmitral gradient from 11.03 +/- 4.70 to 4.63 +/- 2.05 mmHg (p < 0.001) and mitral valve area from 0.99 +/- 0.22 to 1.88 +/- 0.41 cm2 (p < 0.001). Similar significant improvements were seen in group 2. The hemodynamic result was good in 69% of group 1 patients. Tamponade occurred in one patient. Mitral regurgitation grade I or II developed in 8 patients and remained stable in 13 patients. These complication rates were comparable to those seen in group 2. In the group 1, a good result was maintained in 60% of patients after 43 +/- 23 months of follow-up. Although restenosis was observed in 40% of patients, functional amelioration was obtained in most of cases. In the group 2, restenosis was observed in 25% of patients. The data from this study suggest that BMC is effective first therapy in patients aged > or = 60-years with symptomatic mitral stenosis.

Adult↗
PubMed2006

Crystalline style and tissue redistribution in Perna viridis as indicators of Cu and Pb bioavailabilities and contamination in coastal waters.

The concentrations of Cu, Pb, and Zn in the crystalline style (CS) and in the remaining soft tissues (ST) of the green-lipped mussel Perna viridis from 10 geographical sites along the coastal waters off peninsular Malaysia were determined. The CS, compared with the remaining ST, accumulated higher levels of Cu in both contaminated and uncontaminated samples, indicating that the style has a higher affinity for the essential Cu to bind with metallothioneins. The similar pattern of Cu accumulation in the different ST of mussels collected from clean and Cu-contaminated sites indicated that the detoxification capacity of the metallothioneins had not been overloaded. For Pb, higher levels of the metal in the CS than in the remaining ST were found only in mussels collected from a contaminated site at Kg. Pasir Puteh. This indicated a tissue redistribution of Pb due to its binding to metallothioneins for Pb detoxification and the potential of the CS as an indicator organ of Pb bioavailability and contamination. For Zn, the above two phenomena were not found since no obvious patterns were observed (lower levels of Zn in the CS than in the remaining ST) in contaminated and uncontaminated samples due to the mechanism of partial regulation. Generally, all the different STs studied (foot, mantle, gonad, CS, gill, muscle, and byssus) are good biomonitoring tissues for Cu and Pb bioavailabilities and contamination. Among these organs, the CS was found to be the best organ for biomonitoring Cu. The present data also suggest the use of the tissue redistribution of Pb in P. viridis as an indicator of Pb bioavailability and contamination in coastal waters.

Animals↗
PubMed2005

Endocytosis and vesicle trafficking during tip growth of root hairs.

The directional elongation of root hairs, "tip growth", depends on the coordinated and highly regulated trafficking of vesicles which fill the tip cytoplasm and are active in secretion of cell wall material. So far, little is known about the dynamics of endocytosis in living root hairs. We analyzed the motile behaviour of vesicles in the apical region of living root hairs of Arabidopsis thaliana and of Triticum aestivum by live cell microscopy. For direct observation of endocytosis and of the fate of endocytic vesicles, we used the fluorescent endocytosis marker dyes FM 1-43 and FM 4-64. Rapid endocytosis was detected mainly in the tip, where it caused a bright fluorescence of the apical cytoplasm. The internalized membranes proceeded through highly dynamic putative early endosomes in the clear zone to larger endosomal compartments in the subapical region that are excluded from the clear zone. The internalized cargo ended up in the dynamic vacuole by fusion of large endosomal compartments with the tonoplast. Before export to these lytic compartments, putative early endosomes remained in the apical zone, where they most probably recycled to the plasma membrane and back into the cytoplasm for more than 30 min. Endoplasmic reticulum was not involved in trafficking pathways of endosomes. Actin cytoskeleton was needed for the endocytosis itself, as well as for further membrane trafficking. The actin-depolymerizing drug latrunculin B modified the dynamic properties of vesicles and endosomes; they became immobilized and aggregated in the tip. Treatment with brefeldin A inhibited membrane trafficking and caused the disappearance of FM-containing vesicles and putative early endosomes from the clear zone; labelled structures accumulated in motile brefeldin A-induced compartments. These large endocytic compartments redispersed upon removal of the drug. Our results hence prove that endocytosis occurs in growing root hairs. We show the localization of endocytosis in the tip and indicate specific endomembrane compartments and their recycling.

Arabidopsis↗
PubMed2005

Anthropogenic impacts on the distribution and biodiversity of benthic macroinvertebrates and water quality of the Langat River, Peninsular Malaysia.

A study of the impacts of anthropogenic activities on the distribution and biodiversity of benthic macroinvertebrates and water quality of the Langat River (Peninsular Malaysia) was conducted. Four pristine stations from the upstream and 4 stations at the downstream receiving anthropogenic impacts were selected along the river. For 4 consecutive months (March-June 1999), based on the Malaysian DOE (Malaysia Environmental Quality Report 2000, Department of Environment, Ministry of Science, Technology and Environment Malaysia. Maskha Sdn. Bhd. Kuala Lumpur, 86pp; Malaysia Environmental Quality Report 2001, Department of Environment, Ministry of Science, Technology and the Environment Malaysia) water quality index classes, the upstream stations recorded significantly (P<0.05) higher Biological Monitoring Working Party scores and better water quality indices than those of the downstream. The total number of macrobenthic taxa and their overall richness indices and diversity indices were significantly (P<0.05) higher at the upstream stations (54 taxa) than at the downstream stations (5 taxa). The upstream of the Langat River was dominated by Ephemeroptera and chironomid dipterans while other orders found in small quantities included Trichoptera, Diptera, Plecoptera, Odonata, Ephemeraptera, Coleoptera, and Gastropoda. On the other hand, the downstream of the river was mainly inhabited by the resistant Oligochaeta worms Limnodrilus spp. and Branchiodrilus sp. and Hirudinea in small numbers. The relationships between the physicochemical and the macrobenthic data were investigated by Pearson correlation analysis and multiple stepwise regression analysis. These statistical analyses showed that the richness and diversity indices were generally influenced by the total suspended solids and the conductivity of the river water. This study also highlighted the impacts of anthropogenic land-based activities such as urban runoff on the distribution and species diversity of macrobenthic invertebrates in the downstream of the Langat River. The data obtained in this study supported the use of the bioindicator concept for Malaysian rivers. Some sensitive (Trichopteran caddisflies and Ephemeraptera) and resistant species (Oligochaeta such as Limnodrilus spp.) are identified as potential bioindicators of clean and polluted river ecosystems, respectively, for Malaysian rivers.

Animals↗
PubMed2005

Tissue-specific expression and drought responsiveness of cell-wall invertase genes of rice at flowering.

Drought stress near heading reduces grain yield in rice cultivars by inhibiting processes such as anther dehiscence and panicle exsertion. Because cell-wall invertases play an important role in carbon allocation to developing organs, we examined the tissue-specific expression and drought sensitivity of the corresponding genes (OsCIN1-9) at heading in the widely grown cultivar IR64. OsCIN1-5,8 were expressed to varying degrees in flag leaf, panicle, anthers and peduncle at 1 day before heading (1 DBH). When water was withheld for 2 days starting 3 DBH, anthesis and peduncle elongation were halted. At the same time, transcript levels for OsCIN1-5,8 genes were all markedly down-regulated in anthers and/or peduncles but were not affected in flag leaves. Re-watering allowed anthesis and peduncle elongation to proceed and restored expression of OsCIN1-5,8. We conclude that cell-wall invertase genes, as a class, respond rapidly to water deficit in anthers and peduncles and through a reduction in sink strength help to coordinate a delay in anthesis and heading. By contrast, vacuolar invertase OsVIN2 was up-regulated by drought stress in flag leaves, panicles, anthers and peduncles. Although OsCIN1-3,5,8 were active in the peduncle, only OsCIN2 was expressed strongly and preferentially at the base, where cell division and cell elongation occur. OsCIN2 was expressed principally in the primary and secondary vascular systems, consistent with a role in diverting sucrose from the phloem to the dividing and expanding cells of the peduncle, whereas the less abundant OsCIN1,3,5,8 transcripts were found principally in parenchyma cells. The OsCIN2 transcript levels in the base were highest at 1 DBH, when rapid peduncle elongation began. Drought stress halted peduncle elongation and reduced OsCIN2 transcript level to 8% of the control level. On re-watering, peduncle elongation was restored and OsCIN2 transcript level recovered to 24% of the control. The abscisic acid (ABA) level of peduncles increased 7-fold on drought stress and returned to the control level on re-watering. Detached peduncles floated on water elongated little and lost all OsCIN2 transcripts, but on 50-100 microM GA3 they elongated rapidly and maintained high OsCIN2 transcript levels. ABA antagonized both peduncle elongation and maintenance of OsCIN2 transcript levels. We conclude that this antagonism is a potential intervention point for breeding strategies directed at enhancing panicle exsertion during or after drought stress at heading.

Abscisic Acid↗
PubMed2005

Giant presacral neuro-enteric cyst with anomalous sacrum in an adult patient.

A rare case of an adult patient with a giant neuro-enteric cyst in a presacral location is reported. It had unique histological features of a stratified squamous epithelial lining with neuro-epithelial and smooth muscle components. There was associated sacral dysgenesis with spina bifida. The possible pathogenesis of this entity is discussed.

Abortion, Induced↗
PubMed2005

Peginterferon {alpha}-2b and ribavirin therapy in chronic hepatitis C genotype 4: impact of treatment duration and viral kinetics on sustained virological response.

BACKGROUND: The response rates and duration of peginterferon alpha (PEG-IFN-alpha) and ribavirin combination therapy in chronic hepatitis C genotype 4, the prevalent genotype in the Middle East and Africa, are poorly documented. AIMS: To compare the efficacy and safety of 24, 36, or 48 weeks of PEG-IFN-alpha-2b and ribavirin therapy in chronic hepatitis C genotype 4. METHODS: In this prospective, randomised, double blind study, 287 patients with chronic hepatitis C genotype 4 were randomly assigned to PEG-IFN-alpha-2b (1.5 mug/kg) once weekly plus daily ribavirin (1000-1200 mg) for 24 weeks (group A, n = 95), 36 weeks (group B, n = 96), or 48 weeks (group C, n = 96) and followed for 48 weeks after completion of treatment. Early viral kinetics and histopathological evaluation of pre- and post treatment liver biopsies were performed. The primary end point was viral clearance 48 weeks after completion of treatment. RESULTS: Sustained virological response was achieved in 29%, 66%, and 69% of patients treated with PEG-IFN-alpha-2b and ribavirin for 24, 36, and 48 weeks, respectively, by intention to treat analysis. No statistically significant difference in sustained virological response rates was detected between 36 and 48 weeks of therapy (p = 0.3). Subjects with sustained virological response showed greater antiviral efficacy (epsilon) and rapid viral load decline from baseline to treatment week 4 compared with non-responders and improvement in liver histology. The incidence of adverse events was higher in the group treated for 48 weeks. CONCLUSION: PEG-IFN-alpha-2b and ribavirin for 36 or 48 weeks was more effective in the treatment of chronic hepatitis C genotype 4 than treatment for 24 weeks. Thirty six week therapy was well tolerated and produced sustained virological and histological response rates similar to the 48 week regimen.

Adult↗
PubMed2004

Toxicities and tolerances of Cd, Cu, Pb and Zn in a primary producer (Isochrysis galbana) and in a primary consumer (Perna viridis).

Studies on toxicities and tolerances of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in the brown alga Isochrysis galbana and in the green-lipped mussel Perna viridis were conducted by short-term bioassays using endpoints growth production and mortality, respectively. The 5-day EC(50) and 24-h LC(50) of these heavy metals were determined in the brown alga and mussel, respectively. The EC(50) values calculated for the alga were 0.74 mg/l for Cd, 0.91 mg/l for Cu, 1.40 mg/l for Pb and 0.60 mg/l for Zn. The LC(50) values for the mussels were 1.53 mg/l for Cd, 0.25 mg/l for Cu, 4.12 mg/l for Pb and 3.20 mg/l for Zn. These LC(50) values were within the concentration ranges as reported by other authors who used P. viridis as the test organism. Based on these EC(50) and LC(50) values, the alga was most sensitive to Zn, followed by Cd, Cu and Pb while the mussel was most sensitive to Cu, followed by Cd, Zn and Pb. Differences in the trophic levels, metal handling strategies, biology and ecology of the primary producer (brown alga) and the primary consumer (mussel) are believed to be the plausible causes for the different toxicities and tolerances of the metals studied.

Adaptation, Physiological↗
PubMed2004

Allozyme polymorphisms and heavy metal levels in the green-lipped mussel Perna viridis (Linnaeus) collected from contaminated and uncontaminated sites in Malaysia.

It has been widely reported that heavy metal contamination in coastal waters can modify the allozyme profiles of marine organisms. Previous studies have recorded elevated metal concentrations in sediments and mussel tissues off Peninsular Malaysia. In the present study, horizontal starch gel electrophoresis was carried out to estimate the levels of allelic variation of the green-lipped mussel, Perna viridis, collected from one contaminated and three relatively uncontaminated sites off Peninsular Malaysia. Fourteen polymorphic loci were observed. In addition, the concentrations of cadmium, copper, lead, mercury and zinc were determined in the sediments and in the soft tissues of the mussels. Mussels from contaminated site, evidenced by high metal pollution indices (MPI) of the sediment and the mussel tissues, showed the highest percentage of polymorphic loci (78.6%), while those collected from the uncontaminated sites had lower MPI of the sediment and mussel tissue, and exhibited lower percentages of polymorphic loci (35.7-57.1%). The population from the contaminated site showed the highest excess of heterozygosity (0.289) when compared to that of the populations from the three uncontaminated sites (0.108-0.149). Allozyme frequencies at the phosphoglucomutase (PGM; E.C. 2.7.5.1) locus also differed between the contaminated and uncontaminated populations. Previous studies have shown that exposure to heavy metals can select or counter-select for particular alleles at this locus. The present results suggest that allozyme polymorphism in P. viridis is a potential biomonitoring tool for heavy metal contamination but further validation is required.

Animals↗
PubMed2003

Can the byssus of green-lipped mussel Perna viridis (Linnaeus) from the west coast of Peninsular Malaysia be a biomonitoring organ for Cd, Pb and Zn? Field and laboratory studies.

Concentrations of cadmium (Cd), lead (Pb) and zinc (Zn) in total soft tissues (ST) and byssus (BYS) of the green-lipped mussel Perna viridis from 11 different geographical locations off the west coast of Peninsular Malaysia were determined. The metal concentrations distributed between the BYS and ST were compared. The results of this study indicated that higher levels of Cd (1.31 microg/g), Pb (38.49 microg/g) and Zn (206.52 microg/g) were accumulated in the BYS than in the total ST (Cd: 0.29 microg/g; Pb: 8.27 microg/g; Zn: 102.6 microg/g). Semi-static and short period controlled laboratory experiments were also conducted for the accumulation and depuration of Cd, Pb and Zn in the total ST and BYS of P. viridis. The ratios (BYS/ST) for Pb and Cd from the laboratory experiments showed that the total ST accumulated more metals than the BYS. Therefore, these laboratory results disagreed with those found for the field samples. However, the laboratory results for the Zn ratio (BYS/ST) agreed with those of the field samples. It was evident that when compared to the ST, the BYS was a more sensitive biomonitoring organ for Zn while it could be a complementary organ for Cd and Pb in the total ST. Since total ST of P. viridis had been reported to have regulative mechanism for Zn, its BYS can be used as a biomonitoring organ for the identification of coastal areas exposed to Zn pollution.

Animals↗