Severe haemorrhage in neurofibromatoma: a lesson

Neurofibromatosis is a relatively common inherited disease of the nervous system, with a frequency of almost 1 in 3000. It is associated with a wide range of vascular abnormalities. A 62-year-old man with neurofibromatosis presented to us with a sacral haematoma. This was due to spontaneous rupture of a pre-existing neurofibromata. Upon admission the patient was in hypovolaemic shock and required aggressive resuscitation prior to surgery. Haemorrhage following trauma or spontaneous rupture is an uncommon complication of neurofibromatosis. The management is discussed with emphasis on the cause and control of bleeding from these lesions.

Patch test for the detection of contact allergens

Patch Test was done in 340 suspected allergic contact dermatitis patients having different ages of both sexes during the period of January 2000 to December 2003 in the department of Dermatology and Venerology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. Of these 340 cases 145 (42.65%) were male and 195 (57.35%) were female. Among these 340 cases, 250 (73.53%) cases were tested with international standard series allergen (ISS) and 90 (26.47%) cases with cosmetic series allergen (CSS), of which patch test was positive in 125 (50%) cases and 65 (72.22%) cases respectively. The 125 positive cases with ISS consisted of 56% male and 44% female. In 65 CSS positive cases 90.77% were female and 9.23% were male. Highest incidence of positive patch test was found in 61.54% cases in the age group of 30-39 years in ISS and 71.43% cases in the age group of 20-29 yrs in CSS. In ISS--Potassium Dichromate (19.2%), Fragrance mix (17.6%), Nickel Sulphate (15.2%) and PPD (11.2%) were found to be the common allergen and in CSS--Octyl Gallate (27.69%), Getrimide (18.92%), Balsum of Peru (15.38%), Thiomersal (12.31%) were found to be the common allergens.

Removal and recovery of nickel(II) from aqueous solution by loofa sponge-immobilized biomass of Chlorella sorokiniana: characterization studies

The biosorption process for the removal of nickel(II) by loofa sponge-immobilized biomass of Chlorella sorokiniana (LIBCS), a newly developed immobilized biosorbent, was characterized. Effects of environmental factors on metal uptake capacity of LIBCS were studied and compared with free biomass of C. sorokiniana (FBCS). Nickel(II) removal by LIBCS was found to be influenced by pH of the solution, initial metal concentration, and biomass concentration. The biosorption of nickel(II) ions by both LIBCS and FBCS increased as the initial concentration of nickel(II) ions increased in the medium. No loss to biosorption capacity of LIBCS for nickel(II) was found due to the presence of loofa sponge, indeed as compared to FBCS an increase of 25.3% was noted in the biosorption capacity of LIBCS. Maximum biosorption capacities for FBCS and LIBCS were found as 48.08 and 60.38 mg nickel(II)/g, respectively, whereas the amount of nickel(II) ions adsorbed on the plain loofa sponge was 6.1mg/g. During these biosorption studies, LIBCS exhibited excellent physical and chemical stability without any significant release/loss of microalgal biomass from loofa sponge matrix. The kinetics of nickel(II) removal was extremely fast reaching at equilibrium in about 15 min for LIBCS and 20 min for FBCS. The biosorption equilibrium was well described by the Langmuir and Freundlich adsorption isotherms. The biosorption capacities were found to be solution pH dependent and the maximum adsorption was found at a solution pH 4-5. The LIBCS could be regenerated using 75 mM HCl, with up to 98% recovery. The LIBCS were shown to be robust and stable with little decrease in the nickel(II) uptake capacity when used in consecutive seven biosorption-desorption cycles. Continuous removal of nickel(II) from electroplating effluent by LIBCS packed in fixed bed column bioreactor confirm the possibility of developing a biological treatment process for the removal of toxic metals from authentic wastewater.

Seroprevalence of dengu infections amongst the children

Serosurvillance of 650 children of clinically suspected dengue infection based on simple laboratory tests were evaluated to find out the early indicator for diagnosis of dengue infection. The study was conducted among the patients attending the Sir Salimullah Medical College (SSMC) and Mitford Hospital and Popular Diagnostic Center, Dhaka, during July 2002 to September 2002. Of these 650 suspected dengue cases, 294 were in the age group 1-5 years, 206 were in age group 6-10 years and 150 cases in age group 11-15 years, of which Seropositivity was found in 78 (26.53%), 60 (24.12%) and 65 (43.33%) cases respectively. Primary dengue IgM was positive in 123 (60.59%) cases and secondary dengue (IgG & IgM combined or IgG alone) was positive in 80 (39.41%) cases. Leucopenia was found in 90 (75%) cases and Thrombocytopenia was found in 95 (79.16%) cases in primary dengue cases. Similarly in secondary dengue cases TWBC and PLT was decreased in 60 (72.29%) and 65 (78.15%) cases respectively. Haemoconcentration was found in 40 (36.67%) cases of primary dengue and 13 (18%) cases in secondary dengue. Month wise distribution of dengue seropositivity shows that 10 (8.53%) cases was found in July, 175 (50.10%) cases in August and 78 (10.00%) cases in September. This study reveals that seropositivity is highest (43.33%), in the age group 11-15 years and incidence of dengue increased in the month of August. Leucopenia (WBC <or= 5000) and Thrombocytopenia (Patelet count <or= 100000) were two findings that help in the early diagnosis of dengue infection.

Ischemic stroke subtypes in Pakistan: the Aga Khan University Stroke Data Bank

OBJECTIVE

Frequency of ischemic stroke subtypes is influenced by ethnic and geographic variables. Our objective was to identify various stroke subtypes and its determinants at a tertiary care hospital.

METHODS

We prospectively collected data on ischemic stroke subtypes admitted to The Aga Khan University Hospital in Karachi.

RESULTS

A total of 596 patients were enrolled in 22 months in the Aga Khan Universtiy Stroke Registry. These included 393 patients with Ischemic stroke, 126 patients with intracerebral hemorrhage, 50 patients with subarachnoid hemorrhage and others. The ischemic stroke group was classified according to the TOAST criteria and comprised of lacunar 168/393 (42.7%); large artery atherosclerosis 106/393 (26.9%); cardioembolic 24/393 (6.1%); undetermined 80/393 (20.3%); and other determined types 15/393 (3.8%). The high proportion of lacunar strokes in our population may be due to high burden of inadequately treated hypertension and diabetes. Clear cut cardioembolic stroke was relatively infrequent in our population.

CONCLUSION

Lacunar stroke is the most common subtype of stroke in our patient population. This is most likely secondary to uncontrolled hypertension.

Microalgal-luffa sponge immobilized disc: a new efficient biosorbent for the removal of Ni(II) from aqueous solution

AIMS

The aim was to develop a new, efficient and cost-effective biosorbent for the removal of heavy metals from aqueous solution.

METHODS AND RESULTS

A new biosorbent was developed by immobilizing a unicellular green microalga Chlorella sorokiniana within luffa sponge discs and used for the removal of metal ions from aqueous solution. Microalgal-luffa sponge immobilized discs (MLIDs) removed Ni(II) very rapidly, with 97% of equilibrium loading being reached in 5 min. MLIDs were tested for their potential to remove Ni(II) from aqueous solution in fixed-bed column bioreactor. The regenerated MLIDs retained 92.9% of the initial binding capacity for Ni(II) up to five cycles of reuse.

CONCLUSIONS

In this study for the first time, C. sorokiniana biomass immobilized within luffa sponge disc was successfully used as a metal biosorbent for the removal of Ni(II). It appears that MLIDs can be used as an effective biosorbent for efficient removal of Ni(II) or other metals from aqueous solution.

SIGNIFICANCE AND IMPACT OF THE STUDY

MLIDs biosorption system was shown to have good biosorption properties with respect to Ni(II). Efficient metal removal ability of MLIDs, low cost and simplicity of the technique used for the preparation of MILDs could provide an attractive strategy for developing high-affinity biosorption system for heavy metal removal.

Moyamoya disease: an elusive diagnosis

OBJECTIVE AND BACKGROUND

Moyamoya disease is an idiopathic vasculopathy of circle of Willis. Stroke is a common presentation. We describe clinical and radiological features of moyamoya disease in four patients.

SETTING

Tertiary care center in a metropolitan city.

MATERIALS AND METHODS

Patients with moyamoya disease were identified by ICD-9 coding system of the hospital medical records. Demographic characteristics, clinical features/presentation, laboratory investigations and radiological investigations were recorded and analyzed.

RESULTS

Four patients (three children and one adult) presented with hemiparesis. One patient expired during hospital stay. Two patients underwent surgery (synangiosis). EEGs of three patients showed focal abnormalities. Neuroimaging showed ischemic infarctions in all patients. Findings on four vessel digital substraction angiography and/or magnetic resonance angiography were compatible with moyamoya disease.

CONCLUSION

Moyamoya disease should be considered in all young patients, especially children, presenting with stroke.

Petiolar felt-sheath of palm: a new biosorbent for the removal of heavy metals from contaminated water

Biosorption of heavy metals such as Pb2+, Ni2+, Cd2+, Cu2+, Cr3+ and Zn2+ by petiolar felt-sheath of palm (PFP) from contaminated water was examined. PFP was found to efficiently remove all the toxic metal ions with selectivity order of Pb2+ > Cd2+ > Cu2+ > Zn2+ > Ni2+ > Cr3+. The uptake was rapid, with more than 70% completed within 15 min. The bound metal ions were successfully desorbed and the PFP fibrous-biomass remained effective after several adsorption-desorption cycles.

The p85 subunit of phosphoinositide 3-kinase is associated with beta-catenin in the cadherin-based adhesion complex

Cell adhesion is fundamental to establishing and maintaining the discrete tissues in multicellular organisms. Adhesion must be sufficiently strong to preserve tissue architecture, whilst having the capacity to readily dissociate to permit fundamental processes, such as wound repair, to occur. However, very little is known about the signalling mechanisms involved in temporary down-regulation of cell adhesion to facilitate such processes. Cadherins are the principal mediators of cell-cell adhesion in a wide variety of tissues and species and form multi-protein complexes with cytosolic and cytoskeletal proteins to express their full adhesive capacity. In the present study we report that the p85 subunit of phosphoinositide 3-kinase (PI 3-kinase) is associated with the cadherin-based adhesion complex in human epithelial cells. The interaction of p85 with the complex is via beta-catenin. We also show that the interaction of p85 and beta-catenin is direct, involves the N-terminal Src homology domain 2 of p85 and is regulated by tyrosine phosphorylation. These data suggest that PI 3-kinase may play a role in the functional regulation of the cadherin-based adhesion complex.

Depression after stroke-analysis of 297 stroke patients

Stroke is commonly followed by some form of psychiatric disturbance. Association and severity of depression at the 3rd and 12th months after stroke in patients and controls were compared. Two registers of stroke patients were maintained over 2 years period in two different centers--one in Barisal Town and other in Mitford Hospital, Dhaka. A total of 297 first-ever strokes were registered. These patients were called back at the 3rd and 12th month interview and assessment. Beck's Depression Inventory (BDI), with 10 as the cut off point for depression, was applied to 161 of 212 survivors at the 3rd month and to 156 of 195 survivors at the 12th month. At the 3rd month, 41% of patients and 18% of controls were depressed (P<.001) and the difference was maintained at the 12th month 42% versus 19% (P<.05). Univariate risk factors for depression at the 3rd month were female sex, severe prognostic score at the onset of stroke, age more than 70 years, family history of stroke and living alone after stroke. Depression was common among stroke survivors at the 3rd months and its rate did not decrease at 1 year follow-up. Depression could be decreased if post-stroke rehabilitation services are improved. After the development of depression earlier diagnosis and management help a lot to the patients and care givers.

Efficacy of the ketogenic diet in focal versus generalized seizures

Most reports of the ketogenic diet have focused on its efficacy for generalized seizures. Few data are available regarding its effect on focal seizures. We retrospectively studied patients (mean = 7.5 years of age) with medically intractable epilepsy treated by the ketogenic diet. The predominant seizure types in each patient were classified as generalized (100 patients) or focal (34 patients) based on ictal electroencephalograms (EEGs) or seizure semiology and interictal EEG. A seizure reduction of more than 50% compared with baseline was seen in nine patients (27%) with focal seizures and 46 patients (46%) with generalized seizures at 3 months, in 10 patients (30%) with focal seizures and 46 patients (46%) with generalized seizures at 6 months, and in eight patients (24%) with focal seizures and 42 patients (42%) with generalized seizures at 12 months. Differences were not significant. Outcome tended to be better in patients younger than 12 years of age compared with the older age group, but the difference was significant at 6 months only. Our results suggest that some patients with intractable focal epilepsy may respond favorably to the ketogenic diet and that this option should be considered if epilepsy surgery is not possible.

Functional analysis of the yeast Ran exchange factor Prp20p: in vivo evidence for the RanGTP gradient model

Numerous cellular processes rely on the movement of macromolecules into and out of the nucleus. The primary regulator of this movement is the small GTPase Ran. Like other small GTPases, the nucleotide-bound state of Ran is regulated by effectors that enhance the rate of nucleotide exchange or hydrolysis. Current models for vectorial nuclear transport suggest that it is the strict compartmentalization of these Ran effector molecules that generates a gradient of RanGTP between the nucleus and the cytoplasm to impart directionality to the transport process. Here we investigate the mechanism by which the Ran exchange factor is targeted to the nucleus, and test the impact of disrupting this nuclear compartmentalization on nucleocytoplasmic transport in vivo. Our results indicate that in Saccharomycces cerevisiae the nucleotide exchange factor Prp20p can be targeted to the nucleus via a classical nuclear localization sequence. This transport mechanism is dependent both on Ran and the receptor that recognizes the nuclear localization sequence, importin alpha. Mutations in the evolutionarily conserved nuclear localization sequence only partially inhibit nuclear import of Prp20p, suggesting the existence of a secondary mechanism for this critical nuclear targeting. In an in vivo test of the RanGTP gradient model, we demonstrate that overexpression of a functional cytoplasmic exchange factor inhibits cell growth and blocks both protein import and RNA export in wild-type cells that contain the endogenous nuclear Prp20 protein. Taken together, our results provide in vivo evidence for the idea that the compartmentalization of the exchange factor serves as a mechanism for establishing directional nuclear transport.

RAC1 regulates adherens junctions through endocytosis of E-cadherin

The establishment of cadherin-dependent cell-cell contacts in human epidermal keratinocytes are known to be regulated by the Rac1 small GTP-binding protein, although the mechanisms by which Rac1 participates in the assembly or disruption of cell-cell adhesion are not well understood. In this study we utilized green fluorescent protein (GFP)-tagged Rac1 expression vectors to examine the subcellular distribution of Rac1 and its effects on E-cadherin-mediated cell-cell adhesion. Microinjection of keratinocytes with constitutively active Rac1 resulted in cell spreading and disruption of cell-cell contacts. The ability of Rac1 to disrupt cell-cell adhesion was dependent on colony size, with large established colonies being resistant to the effects of active Rac1. Disruption of cell-cell contacts in small preconfluent colonies was achieved through the selective recruitment of E-cadherin-catenin complexes to the perimeter of multiple large intracellular vesicles, which were bounded by GFP-tagged L61Rac1. Similar vesicles were observed in noninjected keratinocytes when cell-cell adhesion was disrupted by removal of extracellular calcium or with the use of an E-cadherin blocking antibody. Moreover, formation of these structures in noninjected keratinocytes was dependent on endogenous Rac1 activity. Expression of GFP-tagged effector mutants of Rac1 in keratinocytes demonstrated that reorganization of the actin cytoskeleton was important for vesicle formation. Characterization of these Rac1-induced vesicles revealed that they were endosomal in nature and tightly colocalized with the transferrin receptor, a marker for recycling endosomes. Expression of GFP-L61Rac1 inhibited uptake of transferrin-biotin, suggesting that the endocytosis of E-cadherin was a clathrin-independent mechanism. This was supported by the observation that caveolin, but not clathrin, localized around these structures. Furthermore, an inhibitory form of dynamin, known to inhibit internalization of caveolae, inhibited formation of cadherin vesicles. Our data suggest that Rac1 regulates adherens junctions via clathrin independent endocytosis of E-cadherin.

Angiogenesis assays: problems and pitfalls

Many studies of angiogenesis inducers and inhibitors rely on in vitro or in vivo models as indicators of efficacy. However, as valuable as these models are, there are limitations to each one of these. This overview describes some of the principal methods now in use and discusses the advantages and some of the limitations of these methods. It is suggested that multiple assays, involving both in vitro and in vivo assays, are at present the best way to minimize the problems inherent in any specific assay.

Co-localization of Rac1 and E-cadherin in human epidermal keratinocytes

The Rac1 small GTP-binding protein is known to be involved in reorganization of the actin cytoskeleton and in regulation of intracellular signal transduction. The assembly and maintenance of cadherin-based cell cell junctions in epidermal keratinocytes is thought to be dependent on activity of Rac1. In this study we have generated green fluorescent protein (GFP)-tagged wild type, dominant negative and constitutively active Rac1 expression vectors and analyzed distribution of Rac1 following microinjection of human SCC12F epidermal keratinocytes. Wild type, dominant negative and constitutively active GFP Rac1 proteins distribute to sites of cell cell adhesion and co-localize with E-cadherin and the catenins. Disruption of cadherin-based junctions by reduction in extracellular calcium concentrations, or by use of antibodies to E-cadherin, results in redistribution of Rac1 away from sites of cell cell interaction but the co-localization with E-cadherin is maintained. In addition, expression of constitutively active GFP Rac1 results in formation of membrane ruffles on the apical surface of cells and intracellular vesicles. Interestingly, co-localization of Rac1 with E-cadherin is maintained in these structures. In contrast to previously published work we find that expression of dominant negative Rac1 neither disrupts cell cell adhesion nor prevents assembly of new cadherin-based adhesion structures.

Learning words through overhearing

Recent research indicates that toddlers can monitor others' conversations, raising the possibility that they can acquire vocabulary in this way. Three studies examined 2-year-olds' (N = 88) ability to learn novel words when overhearing these words used by others. Children aged 2,6 were equally good at learning novel words-both object labels and action verbs-when they were overhearers as when they were directly addressed. For younger 2-year-olds (2,1), this was true for object labels, but the results were less clear for verbs. The findings demonstrate that 2-year-olds can acquire novel words from overheard speech, and highlight the active role played by toddlers in vocabulary acquisition.

Transient expression of the NG2 proteoglycan by a subpopulation of activated macrophages in an excitotoxic hippocampal lesion

Cells that express the NG2 proteoglycan (NG2+ cells) constitute a large glial population in the normal mature rodent brain. They can differentiate into oligodendrocytes but are distinct from mature oligodendrocytes, astrocytes, microglia, and neurons. Changes in NG2+ cells were examined in kainic acid-induced excitotoxic lesions of the hippocampus, and the relationship between NG2+ cells and reactive astrocytes and microglia was investigated between 1 and 90 days after lesioning. Two types of reactive NG2+ cells with altered morphology and increased NG2 immunoreactivity were observed in the lesion. Early changes, consisting of an increase in NG2 immunoreactivity and the number of processes, were apparent 24 h after lesioning and persisted through 3 months. These cells were distinct from reactive astrocytes or activated microglia/macrophages. A second type of reactive NG2+ cells appeared 2 weeks after injection, following an influx of macrophages. They had large, round cell bodies with short processes and expressed the microglia/macrophage antigens OX42 and ED1. Single cells coexpressing NG2 and macrophage/microglial antigens could be isolated from the lesion. The number of NG2+/OX42+ cells gradually declined and disappeared by 3 months after injection. They did not express glial fibrillary acidic protein or the alpha receptor for platelet-derived growth factor, indicating that they are distinct from astrocytes or oligodendrocyte progenitor cells. Cells that coexpressed NG2 and OX42 were never observed in hippocampal slice cultures treated with kainic acid, suggesting that NG2+/OX42+ cells are not derived from endogenous resident brain cells. These findings demonstrate that NG2 expression is transiently upregulated on activated macrophages/microglia that appear during the chronic stage in an excitotoxic lesion in the adult CNS.

SGD1 encodes an essential nuclear protein of Saccharomyces cerevisiae that affects expression of the GPD1 gene for glycerol 3-phosphate dehydrogenase

We here report the identification of the previously uncharacterized SGD1 gene, encoding a 102.8-kDa protein containing a leucine zipper region and a bipartite nuclear localization signal. Deletion of SGD1 results in loss of cell viability, while an increased dosage of SGD1 partially suppresses the osmosensitivity of pbs2 delta and hog1 delta mutants that are defective in the osmosignaling high osmolarity glycerol (HOG) mitogen-activated protein kinase pathway. The rescued mutants display a partially re-established transcriptional control of the osmostress-induced expression of GPD1, a target gene of the HOG pathway encoding NAD(+)-dependent glycerol 3-phosphate dehydrogenase, and a partially recovered hyperosmolarity-induced production of glycerol. Consistent with Sgd1p affecting the transcriptional control of GPD1, a functional green fluorescent protein tagged Sgd1p is localized to the cell nucleus.

Visualizing muscle cell migration in situ

BACKGROUND

Cell migration has been studied extensively by manipulating and observing cells bathed in putative chemotactic or chemokinetic agents on planar substrates. This environment differs from that in vivo and, consequently, the cells can behave abnormally. Embryo slices provide an optically accessible system for studying cellular navigation pathways during development. We extended this system to observe the migration of muscle precursors from the somite into the forelimb, their cellular morphology, and the localization of green fluorescent protein (GFP)-tagged adhesion-related molecules under normal and perturbed conditions.

RESULTS

Muscle precursors initiated migration synchronously and migrated in broad, rather than highly defined, regions. Bursts of directed migration were followed by periods of meandering or extension and retraction of cell protrusions. Although paxillin did not localize to discernible intracellular structures, we found that alpha-actinin localized to linear, punctate structures, and the alpha5 integrin to some focal complexes and/or vesicle-like concentrations. Alterations in the expression of adhesion molecules inhibited migration. The muscle precursors migrating in situ formed unusually large, long-lived protrusions that were polarized in the direction of migration. Unlike wild-type Rac, a constitutively active Rac localized continuously around the cell surface and promoted random protrusive activity and migration.

CONCLUSIONS

The observation of cellular migration and the dynamics of molecular organization at high temporal and spatial resolution in situ is feasible. Migration from the somite to the wing bud is discontinuous and not highly stereotyped. In situ, local activation of Rac appears to produce large protrusions, which in turn, leads to directed migration. Adhesion can also regulate migration.

Cell vacuolation induced by the VacA cytotoxin of Helicobacter pylori is regulated by the Rac1 GTPase

Chronic gastric infection with the Gram-negative bacterium Helicobacter pylori is a major contributing factor in the development of duodenal ulcers and is believed to be a significant risk factor in the development of gastric tumors. The VacA cytotoxin of H. pylori is a 90-kDa secreted protein that forms trans-membrane ion channels. In epithelial cells, VacA activity is associated with the rapid formation of acidic vacuoles enriched for late endosomal and lysosomal markers. Rac1 is a member of the Rho family of small GTP-binding proteins that regulate reorganization of the actin cytoskeleton and intracellular signal transduction and are being shown increasingly to play a role in membrane trafficking events. In this study we report that: (i) green fluorescent-tagged Rac1 localizes around the perimeter of the vacuoles induced by VacA; (ii) expression of dominant negative Rac1 in epithelial cells inhibits vacuole formation; (iii) expression of constitutively active Rac1 potentiates the activity of VacA. Taken together, these data demonstrate a role for Rac1 in the regulation of VacA activity.