A type II ribonuclease H from Leishmania mitochondria: an enzyme essential for the growth of the parasite

Replication of kDNA in the mitochondrion of the kinetoplastid protozoan is an essential process. One of the proteins that may be required for the kDNA replication is the ribonuclease H (RNase H; EC 3.1.26.4). We have identified four distinct ribonuclease H genes in Leishmania, one type I (LRNase HI) and three type II (LRNase HIIA, LRNase HIIB and LRNase HIIC). We detail here molecular characterization of LRNase HIIC. The coding sequence of LRNase HIIC is 1425 bp in length encoding a 474-amino acid protein with a calculated molecular mass of approximately 53 kDa. While LRNase HIIC shares several conserved domains with mitochondrial RNase H from other organisms, it has three extra patches of amino acid sequences unique to this enzyme. Functional identity of this protein as an RNase H was verified by genetic complementation in RNase H-deficient Escherichia coli. The precursor protein may be enzymatically inactive as it failed to complement the E. coli mutant. The mitochondrial localization signal in LRNase HIIC is within the first 40 amino acid residues at the N-terminus. In vitro import of the protein by the mitochondrial vesicles showed that the precursor protein is processed to a 49-kDa protein. Antisense ablation of LRNase HIIC gene expression is lethal to the parasite cells both in vitro and in vivo. This study not only reveals the significance of the LRNase HIIC in the kinetoplast biology but also identifies a potential molecular target for antileishmanial chemotherapy.

Down-regulation of 7SL RNA expression and impairment of vesicular protein transport pathways by Leishmania infection of macrophages

The parasitic protozoan Leishmania specifically manipulates the expression of host macrophage genes during initial interactions, as revealed by mRNA differential display reverse transcription-PCR and cDNA microarray analyses. The genes that are down-regulated in mouse (J774G8) or human (U937) macrophages upon exposure to Leishmania include small RNA transcripts from the short interspersed element sequences. Among the short interspersed element RNAs that are down-regulated is 7SL RNA, which is the RNA component of the signal recognition particle. Because the microbicidal functions of macrophages profoundly count on vesicular protein transport processes, down-regulation of 7SL RNA may be significant in the establishment of infection by Leishmania in macrophage phagolysosomes. To evaluate whether down-regulation of 7SL RNA results in inhibition of signal recognition particle-mediated vesicular protein transport processes, we have tested and found that the targeting of proteins to the endoplasmic reticulum and plasma membrane and the secretion of proteins by macrophages are compromised in Leishmania-infected J774G8 and U937 cells. Knocking down 7SL RNA using small interfering RNA mimicked the effect of exposure of macrophages to Leishmania. The overexpression of 7SL RNA in J774G8 or U937 cells made these cells resistant to Leishmania infection, suggesting the possible biological significance of down-regulation of 7SL RNA synthesis in the establishment of infection by Leishmania. We conclude that Leishmania down-regulates 7SL RNA in macrophages to manipulate the targeting of many proteins that use the vesicular transport pathway and thus favors its successful establishment of infection in macrophages.

Observation of quantum Hall "valley Skyrmions"

We report measurements of the interaction-induced quantum Hall effect in a spin-polarized AlAs two-dimensional electron system where the electrons occupy two in-plane conduction band valleys. Via the application of in-plane strain, we tune the energies of these valleys and measure the energy gap of the quantum Hall state at filling factor nu = 1. The gap has a finite value even at zero strain and, with strain, rises much faster than expected from a single-particle picture, suggesting that the lowest energy charged excitations at nu = 1 are "valley Skyrmions."

Negative regulation of the expressions of cytokeratins 8 and 19 by SLUG repressor protein in human breast cells

Invasiveness of tumor cells is often determined by the profile of their expressed genes. To determine the gene expression differences between an invasive and a non-invasive human breast tumor cells, we selected BT-549 (invasive) and MDA-MB-468 (non-invasive) cells, and compared their transcriptomes by cDNA microarray analysis. Among the significant differences in gene expressions, notable are the up-regulation of cytokeratins 8 and 19, and down-regulation of metallothioneins 1G and IL in MDA-MB-468 cells. Since MDA-MB-468 cells do not express SLUG, a member of a small family of E2-box-binding zinc finger silencer proteins, we studied whether the cytokeratin gene overexpressions in these cells are due to the absence of SLUG. Inducible expression of SLUG in MDA-MB-468 cells inhibited the expressions of the cytokeratin 8 and 19 but not others as was revealed by microarray analysis. Similarly, siRNA knock down of SLUG in BT-549 cells increased the expressions of those cytokeratin mRNAs. SLUG levels in the cell regulated the function of cytokeratins 8 and 19 gene promoters. We conclude that the expressions of cytokeratins and metallothioneins may be associated with the differential invasive behaviors of these breast tumor cells and SLUG may have regulatory roles in this process.

Expression, purification, and characterization of Leishmania donovani trypanothione reductase in Escherichia coli

Trypanothione reductase (TR) is an NADPH-dependent flavoprotein oxidoreductase central to thiol metabolism in all the trypanosomatids including Leishmania. The unique presence of this enzyme in trypanosomatids and absence in mammalian host make this enzyme an attractive target for the development of the antileishmanials. Complete open reading frame encoding trypanothione reductase from Leishmania donovani (Dd8 strain, causative agent of Indian visceral leishmaniasis) was cloned, sequenced, and expressed in Escherichia coli strain BL21 (DE3) as glutathione S-transferase fusion protein. The conditions were developed for overexpression of fusion protein in soluble form and purification of the recombinant protein to homogeneity. The recombinant LdTR was 54.68 kDa in size, dimeric in nature, and reduces oxidized trypanothione to reduced form. The kinetic parameters for trypanothione disulfide are K(m), 50 microM; k(cat), 18,181 min(-1); and k(cat)/K(m), 6.06x10(6) M(-1) s(-1). The yield of recombinant LdTR was approximately 16 mg/L bacterial culture and accounted for 6% of the total soluble proteins. The expressed protein was inhibited by known TR inhibitors as well as by SbIII, the known antileishmanial compound. This is the first report of large-scale production of any leishmanial TR in E. coli.

Regulation of BRCA2 gene expression by the SLUG repressor protein in human breast cells

The expression of the breast cancer susceptibility protein BRCA2 is highly regulated in human breast, ovary, and pancreatic cells. BRCA2 is not expressed in the non-dividing cells, and expression is cell cycle stage-dependent and is elevated in the sporadic cancer cells. Mutational analysis of the upstream sequence of the human BRCA2 gene revealed an E2-box-containing silencer at the -701 to -921 position. The E2-box is essential for the cell-cycle stage-dependent activity of the silencer. We affinity-purified a 29-kDa silencer-binding protein (SBP) from the nuclear extracts of human breast cells BT-549 and MDA-MB-231. We explored whether the E2-box-binding repressor protein SLUG, which is of similar molecular size, is involved in the silencing process. Supershift assay with the purified SBP and anti-SLUG antibody revealed the identity of the SBP as SLUG. We found that silencer is inactive in the human breast cancer cells such as MDA-MB-468 and MCF-7 that do not express SLUG, further suggesting the involvement of SLUG in the BRCA2 gene silencing. Inducible expression of human SLUG in the dividing MDA-MB-468 cells reduced BRCA2 RNA levels with the activation of the silencer. Furthermore, small interfering RNA-mediated knockdown of SLUG mRNA in the BT-549 cells caused inhibition of the silencer function. Chromatin immunoprecipitation assays suggested that SLUG mediates its action by recruiting C-terminal-binding protein-1 (CtBP-1) and histone deacetylase-1 (HDAC-1) at the silencer E2-box. The general HDAC inhibitor, trichostatin A, inhibited the SLUG-mediated regulation of the silencer function. It thus appears that SLUG is a negative regulator for BRCA2 gene expression.

Value of arsenic-free drinking water to rural households in Bangladesh

Using contingent valuation survey data for about 2700 households in rural Bangladesh, and applying a multinomial logit model, the paper estimates the value of arsenic-free drinking water to the rural people. The estimates indicate that the rural people in arsenic-affected areas of Bangladesh place a low value on arsenic-free drinking water. It is about 10-14 percent of the amount they are willing to pay for piped water and only about 0.2-0.3 percent of the average household income. The implication of the result is that robust but costly arsenic reduction technologies such as activated alumina technology may find little social acceptance, unless heavily subsidized.

Bilateral internuclear ophthalmoplegia following head injury

A 40-year-old female after a closed head injury presented with bilateral internuclear ophthalmoplegia. Attempted convergence was abnormal and MRI revealed the focal hemorrhage in the medial longitudinal fasciculus region by showing bright signal in the a pontomesencephalic region in the midline on both T1 and T2 weighted images. The patient regained normal ocular mobility after six months of the injury. The medial longitudinal fasciculus, which is believed to be lesioned in cases of internuclear ophthalmoplegia, is an unusual and rare finding, particularly in patients victims of head injury without further neurological signs. Isolated internuclear ophthalmoplegia should be considered in the differential diagnosis when one encounters an adduction deficit in a patient suffering head injury.

Polyneuropathy with osteosclerotic myeloma--POEMS syndrome

A 55-years-old male, who presented with insidious onset gradually progressive sensorimotor polyneuropathy, POEMS-syndrome was diagnosed based on polyneuropathy, splenomegaly, hypothyroidism, the presence of IgG-monoclonal serum protein with osteosclerotic lesions and hyperpigmention of skin. Biopsy of the osteosclerotic lesion from the right superior pubic rami was consistent with plasmocytoma. Electrophysiological studies revealed demyelinating sensorimotor neuropathy and biopsy from sural nerve showed demyelinating neuropathy with secondary axonopathy. The patient showed improvement with radiotherapy. This is a rare systemic disease from the clinical spectrum of plasma cell dyscrasias with polyneuropathy. The importance of POEMS syndrome in the differential diagnosis of polyneuropathies has been emphasized.

Early white matter changes in Wilson disease

We describe a 12 years old male who presented with one year history of cognitive decline with extrapyramidal features. Wilson disease was diagnosed on basis of biochemical studies and MRI. MRI showed increased signal intensity on T2 weighted images in basal ganglia and supratentorial with infratentorial gray and white matter. Our patient developed white matter changes early in course of disease.

Neurocysticercosis presenting as Weber's syndrome

This case report describes a rare, non-epileptic manifestation of neurocysticercosis where a 22-year-old male presented with acute onset right 3rd nerve palsy with left hemiplegia (Weber syndrome). Computerized tomography and magnetic resonance imaging revealed cysticercus granuloma. The patient improved and became asymptomatic with steroid treatment. Recognizing this clinical entity would avoid unnecessary antituberculous treatment and surgical intervention.

Patient with limb girdle dystrophy presenting with dopa-responsive dystonia--a case report

Dopa-responsive dystonias are rare. We report a 14-year-old male who was diagnosed as a case of limb girdle dystrophy and had features suggestive of dopa-responsive dystonia.

Cauda-conus syndrome resulting from neurocysticercosis

A 60-year-old male, presented with insidious onset, gradually progressive, burning paresthesia over the saddle area, sphincteric disturbance, impotence and paraparesis. Investigations revealed a ring-enhancing lesion in the conus medullaris suggestive of neurocysticercosis. This was supported by quantitative enzyme-linked immunosorbant assay from purified cell fraction of taenia solium cysticerci. On treatment with steroids he showed marked improvement.

Atomic scale imaging and spectroscopy of a CuO(2) plane at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta)

We have used a scanning tunneling microscope to demonstrate that a single CuO2 plane can form a stable and atomically ordered layer at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta). In contrast to previous studies on high-T(c) surfaces, the CuO2-terminated surface exhibits a strongly suppressed tunneling conductance at low voltages. We consider a number of different explanations for this phenomena and propose that it may be caused by how the orbital symmetry of the CuO2 plane's electronic states affects the tunneling process.

Sertraline in chronic tension-type headache

OBJECTIVES

To study the effect of Sertraline, a selective serotonin reuptake inhibitor in chronic tension type headache (CTTH) in a double blind placebo controlled randomized trial.

MATERIAL AND METHODS

The study design was a double blind placebo controlled randomized study of 50 patients, over a period of 10 weeks including run-in period of two weeks, treatment period four weeks, and follow-up four weeks. The diagnosis of CTTH was based on criteria given by International Headache Society (IHS). The overall response was graded in terms of headache index, analgesic intake per week and percentage reduction in headache frequency using chi-square and 't' test. Anxiety and depression was assessed using Hamilton Rating Scale.

RESULTS

The mean analgesic intake per week declined from 4.34 +/- 0.736 tab/week to 1.07 +/- 0.592 tab/week in sertraline group (p < 0.01) while reduction in placebo group was not significant (3.98 +/- 0.729 tab/week to 2.94 +/- 0.665 tab/week) (p > 0.05). The reduction in headache index and percentage reduction in frequency of headache was not significant in drug treatment group. Side effects were seen in 24.4% of patients nausea, nervousness and dizziness being the commonest.

CONCLUSION

The drug treatment group showed a significant decline in analgesic intake per week. The study result shows that sertraline can be a useful alternative to amitryptiline in those patients who fail to respond or cannot tolerate it.

Induction and transmission of cytogenetic toxic effects of 5-fluorouracil in male germline cells of Swiss mice

Cytogenetic toxicity after a single intraperitoneal exposure of three different doses (5,10 and 15 mg/kg) of 5-fluorouracil (5-FU) and its transmission in the male germline cells of Swiss mice was assessed. At 24 hrs post-treatment each of the doses of 5-FU induced statistically highly significant number of chromosomal aberrations, mostly random chromatid breaks, in the spermatogonial cells with maximum aberrations in the lowest dose. Primary spermatocytic chromosome analysis at week 4 post-treatment showed the presence of a statistically significant number of aberrant spermatocytes with atypical bivalents, mostly with autosomal and/or XY univalents. Sperm morphology assay at week 8 post-treatment exhibited higher percentages of abnormal sperm, but were not statistically significant. This indicated the gradual decline in the transmission of the induced cytogenetic toxic effects of 5-FU from spermatogonia to sperm, which might be because of gradual elimination of the grossly affected spermatogonial cells during the course of spermatogenesis.

Mapping the one-dimensional electronic States of nanotube peapod structures

Arrays of C60 molecules nested inside single-walled nanotubes represent a class of nanoscale materials having tunable properties. We report electronic measurements of this system made with a scanning tunneling microscope and demonstrate that the encapsulated C60 molecules modify the local electronic structure of the nanotube. Our measurements and calculations also show that a periodic array of C60 molecules gives rise to a hybrid electronic band, which derives its character from both the nanotube states and the C60 molecular orbitals.

Case report. Orbital metastasis from gall bladder carcinoma

Clinical presentation of an extraabdominal metastasis from carcinoma of the gall bladder is rare. Orbital metastasis from gall bladder carcinoma has not been previously reported. We report a case of a 40-year-old woman who developed orbital metastasis from carcinoma of the gall bladder.

An integrated computational pipeline and database to support whole-genome sequence annotation

We describe here our experience in annotating the Drosophila melanogaster genome sequence, in the course of which we developed several new open-source software tools and a database schema to support large-scale genome annotation. We have developed these into an integrated and reusable software system for whole-genome annotation. The key contributions to overall annotation quality are the marshalling of high-quality sequences for alignments and the design of a system with an adaptable and expandable flexible architecture.

Apollo: a sequence annotation editor

The well-established inaccuracy of purely computational methods for annotating genome sequences necessitates an interactive tool to allow biological experts to refine these approximations by viewing and independently evaluating the data supporting each annotation. Apollo was developed to meet this need, enabling curators to inspect genome annotations closely and edit them. FlyBase biologists successfully used Apollo to annotate the Drosophila melanogaster genome and it is increasingly being used as a starting point for the development of customized annotation editing tools for other genome projects.

Single small enhancing computed tomographic (CT) lesions in Indian patients with new-onset seizures. A prospective follow-up in 75 patients

This study was planned to observe the clinical and radiological course of single small enhancing CT lesions in Indian patients presenting with new-onset-seizures. In this study, 75 patients with new-onset seizures and a single enhancing CT lesion were prospectively followed up for 1 year. All patients fulfilled the criteria of cysticercus granuloma. The repeat CT scans were performed 2 months after the first CT scan. Antiepileptic drug therapy was the only form of treatment given. The majority of patients were below 20 years of age. Simple partial seizure, with or without secondary generalization, was the commonest type of seizure encountered in these patients. In follow-up CT scans 84% of patients showed either disappearance or regression in the size of lesion. The proportion of patients showing complete disappearance of CT lesions was 0.73 (95% CI, 0.61-0.80). In 11 (15%) patients the lesions were calcified. In nine patients, in whom the lesion had persisted or regressed, another follow-up CT scan (6 months after the second scan) revealed either complete disappearance or calcification of the lesions. The majority (86.6%) of patients remained seizure free for 1 year after starting antiepileptic drugs. Ten patients experienced seizure recurrences within the first month of therapy. The proportion of patients who remained seizure free was 0.86 (95% CI, 0.76-0.92). Four patients experienced seizure recurrence even after complete disappearance of CT lesions. In the majority of patients the lesions disappeared spontaneously and in a few the lesions calcified; hence these patients did not require anticysticercal therapy. Antiepileptic therapy was helpful in controlling further recurrences of seizures in most of the patients. A few patients experienced seizures even after disappearance of CT lesions.

Recognizing phosphatidylinositol 3-phosphate

Phosphatidylinositol 3-phosphate directs the endosomal localization of regulatory proteins by binding to FYVE and PX domains. New structures of these domains complexed with the phosphoinositide headgroup show how interactions with phosphate and hydroxyl groups differentiate this lipid from all others.

Kinetics and pH dependence of light-induced deprotonation of the Schiff base of rhodopsin: possible coupling to proton uptake and formation of the active form of Meta II

In this paper we first review what is known about the kinetics of Meta II formation, the role and stoichiometry of protons in Meta II formation, the kinetics of the light-induced changes of proton concentration, and the site of proton uptake. We then go on to compare the processes that lead to the deprotonation of the Schiff base in bacteriorhodopsin with rhodopsin. We point out that the similarity of the signs of the light-induced electrical signals from the two kinds of oriented pigment molecules could be explained by bacteriorhodopsin releasing a proton from its extracellular side while rhodopsin taking up a proton on its cytoplasmic side. We then examined the pH dependence of both the absorption spectrum of the unphotolyzed state and the amplitude and kinetics of Meta II formation in bovine rhodopsin. We also measured the effect of deuteration and azide on Meta II formation. We concluded that the pKa of the counter-ion to the Schiff base of bovine rhodopsin and of a surface residue that takes up a proton upon photolysis are both less than 4 in the unphotolyzed state. The data on pH dependence of Meta II formation indicated that the mechanisms involved are more complicated than just two sequential, isospectral forms of Meta II in the bleaching sequence. Finally we examined the evidence that, like in bacteriorhodopsin, the protonation of the Schiff bases's counter-ion (Glu113) is coupled to the changing of the pKa of a protonatable surface group, called Z for rhodopsin and tentatively assigned to Glu134. We conclude that there probably is such a coupling, leading to the formation of the active form of Meta II.

Familial intrahepatic cholestasis 1: studies of localization and function

Mutations in the FIC1 gene constitute the molecular defect in familial intrahepatic cholestasis I (Fic1 [Byler's disease]) and benign recurrent intrahepatic cholestasis. This report describes the localization of Fic1 in rat liver and intestine, as well as biochemical and transfection studies that support its function as an energy-dependent aminophospholipid translocase. Immunocytochemistry of rat liver and immunoblotting of membrane fractions localized Fic1 to the canalicular, but not basolateral, plasma membrane domain. In the small intestine, Fic1 was localized to the apical membrane of epithelial cells. The distribution of Fic1 in liver plasma membrane fractions from control and taurocholate-treated rats correlated positively with adenosine triphosphate (ATP)-dependent aminophospholipid (phosphatidyl-serine) translocase activity. In canalicular membrane vesicles, translocase activity had an initial velocity of 3.3 nmol phosphatidylserine (PS) translocated per milligram of protein per minute and a K(m) (ATP) = 1.2 mmol/L; was inhibited by vanadate, N-ethylmaleimide, sodium azide, and calcium; and was unidirectional (i.e., from the outer to the inner canalicular plasma membrane leaflet). Transient transfection of CHOK1 cells with FIC1 cDNA resulted in appearance of FIC1 in membrane preparations and energy-dependent PS translocation in cells. These studies indicate that FIC1 is a canalicular P-type ATPase that participates in maintaining the distribution of aminophospholipids between the inner and outer leaflets of the plasma membrane. How this process produces cholestasis is under study.

Mitogenic signaling by cyclic adenosine monophosphate in chromaffin cells involves phosphatidylinositol 3-kinase activation

Increase of intracellular cyclic adenosine monophosphate by the permeant cyclic adenosine monophosphate analog, 8-(4-chlorophenylthio)-adenosine 3':5'- cyclic monophosphate, is mitogenic for normal adult rat chromaffin cells. The mitogenic effect is blocked by the phosphatidylinositol 3-kinase inhibitor, LY294002, and is associated with accumulation of phosphorylated Akt and p70S6 kinase, suggesting that cyclic adenosine monophosphate activates Type l phosphatidylinositol 3-kinase. The mechanism of activation was examined in PC12 pheochromocytoma cells, which are neoplastic chromaffin cells that exhibit many of the biochemical characteristics of their normal counterparts. Incubation of PC12 cells with 8-(4-chlorophenylthio)-adenosine 3':5'- cyclic monophosphate led to a significant increase in total phosphatidylinositol 3-kinase activity that was sensitive to low concentrations of LY294002. The increase was maximal at 1 h and returned to basal levels within six hours. Immunoprecipitation studies showed no increase in phosphatidylinositol 3-kinase activity in anti-phosphotyrosine immune complexes from PC12 cells stimulated by 8-(4-chlorophenylthio)-adenosine 3':5'- cyclic monophosphate, in contrast to cells stimulated by nerve growth factor. Instead, activity was demonstrated in association with p110gamma and p85. These findings suggest that cyclic adenosine monophosphate causes activation of Types IA and IB phosphatidylinositol 3-kinase by a novel mechanism in chromaffin and pheochromocytoma cells. That activation may contribute to chromaffin cell proliferation and to the development and progression of pheochromocytomas. J. Cell. Biochem. Suppl. 36: 89-98, 2001.

Cytogenetic toxicity of vincristine

The anticancer drugs vincristine sulphate (VCR) and cyclophosphamide (CTX) were tested for their cytogenetic effects in the bone marrow cells of Swiss mice. The end points investigated were chromosomal aberrations and mitotic index at 24 hours posttreatment and micronuclei (MN) at 30 hours posttreatment in bone marrow cells of male and female mice after a single intraperitoneal exposure. The doses tested were VCR 0.25, 0.5, and 1.0 mg/kg and CTX 40 mg/kg b.w. of mice. Significant percentages of chromosomal aberrations and significant numbers of micronuclei per thousand polychromatic erythrocytes (PCEs) that were induced were recorded from bone marrow of each of the VCR-treated groups of mice. There were no significant differences between the percentages of dividing cells in the VCR-treated group and the vehicle control groups of mice. Peculiarly, in the chromosomal aberration study, the male mice were found to be more responsive to VCR than the females, and the aberrations per hundred metaphases were found to be decreased when the dose of VCR was increased. The percentage of dividing cells was also higher with the lowest dose of VCR tested. However, there was a dose-dependent, but nonlinear, increase in MN per thousand PCEs. The results were compared with the already available fragmentary and self-contradictory data on the genotoxicity of VCR in mice and in other mammalian test systems.

S-phase dependent cytogenetic toxicity of 5-fluorouracil in bone marrow cells of mice

The in vivo cytogenetic toxicity of three different doses (5,10 and 15 mg/kg) of 5-fluorouracil (5-FU) (in Fluracil) was assessed in bone marrow cells of mice. At 24 hrs post-treatment the induced chromosomal aberrations, mostly chromatid breaks and fragments, by all the three different concentrations of 5-FU were found statistically significant. However, mitotic index study at 24 hrs post-treatment indicated it as nonmitotoxic. At 30 hrs posttreatment, all the three doses of 5-FU induced a statistically significant number of micronuclei per thousand polychromatic erythrocytes. This indicated 5-FU as nonmitotoxic but highly clastogenic in bone marrow cells of mice.

Dynamin inhibits phosphatidylinositol 3-kinase in hematopoietic cells

Phosphatidylinositol 3-kinase (PI 3-kinase) plays a role in late stages of endocytosis as well as in cellular proliferation and transformation. The SH3 domain of its regulatory p85 subunit stimulates the GTPase activity of dynamin in vitro. Dynamin is a GTPase enzyme required for endocytosis of activated growth factor receptors. An interaction between these proteins has not been demonstrated in vivo. Here, we report that dynamin associates with PI 3-kinase in hematopoietic cells. We detected both p85 and PI 3-kinase activity in dynamin immune complexes from IL-3-dependent BaF3 cells. However, this association was significantly reduced in BaF3 cells transformed with the BCR/abl oncogene. After transformation only a 4-fold increase in PI 3-kinase activity was detected in dynamin immune complexes, whereas grb2 associated activity was elevated 20-fold. Furthermore, dynamin inhibited the activity of both purified recombinant and immunoprecipitated PI 3-kinase. In BaF3 cells expressing a temperature-sensitive mutant of BCR/abl, a significant decrease in p85 and dynamin association was observed 4 h after the induction of BCR/abl activity. In contrast, in IL-3-stimulated parental BaF3 cells, this association was increased. Our results demonstrate an in vivo association of PI 3-kinase with dynamin and this interaction regulates the activity of PI 3-kinase.

Characterization and expression of the Douglas-fir luminal binding protein (PmBiP)

The endoplasmic reticulum (ER) molecular chaperone, BiP, plays a role in the cotranslational translocation and subsequent folding and assembly of newly synthesized proteins targeted to the ER and secretory pathway. The sequence encoding a Douglas-fir (Pseudotsuga menziesii [Mirb] Franco) BiP homologue (PmBiP) was identified by differential screening of a seedling cDNA library. Southern blotting indicated that PmBiP is most likely present as a single copy. The deduced amino acid sequence of PmBiP contains an HEEL tetrapeptide sequence which functions to retain PmBiP in the ER and is different from HDEL commonly found in angiosperm plant BiPs. Amino acid sequence alignment and phylogenetic analysis show that PmBiP is highly similar to other plant BiPs yet forms a distinct phylogenetic subgroup which is separate from the angiosperm BiPs. Northern and western blotting revealed that PmBiP is subject to developmental regulation during seed development, germination, and early seedling growth and is seasonally regulated in needles of young seedlings.

Pathological laughter as heralding manifestation of left middle cerebral artery territory infarct: case report and review of literature

Clinical, radiological and pathological studies in patients with stroke, presenting with pathological laughter as heralding manifestation, have shown lesions in the internal capsule and thalamus, basal ganglion, hypothalamus and ventral pons. In this report a patient with similar manifestation and having a cortical infarct in the territory supplied by superior division of middle cerebral artery is being presented. Our case suggests possible influence of dominant cerebral hemisphere, especially of Broca's area, on the motor control of laughter.

Profile of anemia in children after liver transplantation

BACKGROUND

Clinical and hematological profile of chronic anemia in children after orthotopic liver transplantation (OLT) is unknown.

METHODS

We prospectively studied children after orthotopic liver transplantation (OLT) with hemoglobin levels < 2 standard deviation of age appropriate mean for > 6 months. Investigations included hemogram, reticulocyte count, peripheral blood smear, serum vitamin B-12, folic acid levels, iron studies, Coomb's tests, serum erythropoietin (EPO) levels, and stool and urine tests for occult blood.

RESULTS

Fifty-six participants (22 male and 34 female, mean age 82.9 months, range 20-232, mean post-OLT duration 48.8 months, range 6-132) were studied. The causes of anemia were idiopathic (32), iron deficiency (4), viral infections (2, HIV=1, parvovirus=1), and lymphoproliferative disease (2). Fifteen participants showed spontaneous recovery within 1-6 months. Thirty-one children with idiopathic anemia had low or normal EPO levels (mean 7.33 mmicro/L, range <2.5 to 15.9, normal 4-24). When outliers (iron deficiency=4, HIV disease= 1) were excluded, there was no statistical correlation between hematocrits and EPO levels. Serum vitamin B-12 levels (n=52) were elevated (normal 110-930 pg/ml) (mean=1,186 pg/ml) in 32 (61.5%) and were significantly higher in those with abnormal liver function tests.

CONCLUSION

Anemia is a common problem in children after OLT. More than half the participants had anemia of unknown etiology with an inappropriate EPO response for the degree of anemia. The normal negative correlation between hematocrit and EPO was lost in these children. The observation regarding serum vitamin B-12 levels requires further study.

Transgenic plants expressing cationic peptide chimeras exhibit broad-spectrum resistance to phytopathogens

Here we describe a strategy for engineering transgenic plants with broad-spectrum resistance to bacterial and fungal phytopathogens. We expressed a synthetic gene encoding a N terminus-modified, cecropin-melittin cationic peptide chimera (MsrA1), with broad-spectrum antimicrobial activity. The synthetic gene was introduced into two potato (Solanum tuberosum L.) cultivars, Desiree and Russet Burbank, stable incorporation was confirmed by PCR and DNA sequencing, and expression confirmed by reverse transcription (RT)-PCR and recovery of the biologically active peptide. The morphology and yield of transgenic Desiree plants and tubers was unaffected. Highly stringent challenges with bacterial or fungal phytopathogens demonstrated powerful resistance. Tubers retained their resistance to infectious challenge for more than a year, and did not appear to be harmful when fed to mice. Expression of msrA1 in the cultivar Russet Burbank caused a striking lesion-mimic phenotype during leaf and tuber development, indicating its utility may be cultivar specific. Given the ubiquity of antimicrobial cationic peptides as well as their inherent capacity for recombinant and combinatorial variants, this approach may potentially be used to engineer a range of disease-resistant plants.

Structure of the VHS domain of human Tom1 (target of myb 1): insights into interactions with proteins and membranes

VHS domains are found at the N-termini of select proteins involved in intracellular membrane trafficking. We have determined the crystal structure of the VHS domain of the human Tom1 (target of myb 1) protein to 1.5 A resolution. The domain consists of eight helices arranged in a superhelix. The surface of the domain has two main features: (1) a basic patch on one side due to several conserved positively charged residues on helix 3 and (2) a negatively charged ridge on the opposite side, formed by residues on helix 2. We compare our structure to the recently obtained structure of tandem VHS-FYVE domains from Hrs [Mao, Y., Nickitenko, A., Duan, X., Lloyd, T. E., Wu, M. N., Bellen, H., and Quiocho, F. A. (2000) Cell 100, 447-456]. Key features of the interaction surface between the FYVE and VHS domains of Hrs, involving helices 2 and 4 of the VHS domain, are conserved in the VHS domain of Tom1, even though Tom1 does not have a FYVE domain. We also compare the structures of the VHS domains of Tom1 and Hrs to the recently obtained structure of the ENTH domain of epsin-1 [Hyman, J., Chen, H., Di Fiore, P. P., De Camilli, P., and Brünger, A. T. (2000) J. Cell Biol. 149, 537-546]. Comparison of the two VHS domains and the ENTH domain reveals a conserved surface, composed of helices 2 and 4, that is utilized for protein-protein interactions. In addition, VHS domain-containing proteins are often localized to membranes. We suggest that the conserved positively charged surface of helix 3 in VHS and ENTH domains plays a role in membrane binding.

Regulation of NADPH-cytochrome P450 reductase expressed during Douglas-fir germination and seedling development

NADH-cytochrome P450 is a key enzyme that transfers electrons from NADPH to the cytochrome P450 family of enzymes. To begin to determine the regulation of CPR gene expression and enzyme activity in Douglas-fir a full-length cDNA was isolated from a seedling lambda ZAP cDNA library and the ORF was used to develop a synthetic CPR-peptide-based antiserum. Northern blot analysis indicated CPR expression was regulated both developmentally prior to seed maturation and during germination, and differentially in the cotyledons, radicle and megagametophyte of seed and seedling tissues. The CPR-peptide antiserum detected a single CPR in seed and seedling microsomes analyzed by western blot of two-dimensional SDS-polyacrylamide gels. In microsomal extracts from whole seeds and seedlings, the amount of CPR protein remained constant while NADPH:cytochrome c reductase activity increased during stratification, germination and early seedling development. In contrast to cotyledons and megagametophyte, the level of CPR protein detected in radicles was higher than expected when compared to the amount of CPR transcript.

Non-epileptic manifestations in patients with single enhancing computed tomography lesions

OBJECTIVES AND METHODS

Single enhancing lesions are common computed tomographic (CT) abnormality in patients with epilepsy. In this series we are reporting 13 unusual cases with varied non-epileptic neurological manifestations in patients with ring or disk enhancing CT lesions.

RESULTS

Acute, stroke like non-vascular focal neurological deficits (hemiparesis in four patients, and crural monoparesis, Broca's aphasia, homonymous hemianopia, hemichorea in one patient each) were frequent non-epileptic manifestations. Episodic vascular type of headache was seen in three patients, one patient had headache because of raised intracranial pressure. One patient presented with acute confusional state. All these patients were treated symptomatically, and with oral corticosteroids. CT lesions disappeared in 8-12 weeks time in all patients except in one patient with chorea where the lesion calcified. Significant clinical improvements were noted in all the patients.

CONCLUSIONS

Several non-epileptic manifestations can also be associated with single enhancing CT lesions, and like epileptic disorders these disorders also have a benign course. Corticosteroids, probably, hasten the clinical improvement and produce early resolution of the CT lesions.

Potential transmission of the cytogenetic effects of cisplatin in the male germline cells of Swiss mice

Cisplatin (CP) (in Oncoplatin), a widely used drug in cancer chemotherapy, and cyclophosphamide (CY) (in Endoxan), another anticancer drug, were investigated as the test chemical and positive control, respectively, for their cytogenetic effects on spermatogonia of mice at 24 hours post-treatment after a single exposure. The different doses of the chemicals tested were CP 2, 3, 5 mg/kg and CY 40 mg/kg b.w. of mice. Each of the doses of CP induced a significant number of chromosomal aberrations, mostly chromatid breaks and fragments. The potential transmission of such cytogenetic effects of the chemicals from spermatogonia to spermatocytes was assessed at week 4 post-treatment from the primary spermatocytes, which showed a significant number of aberrant spermatocytes with atypical bivalents viz. spermatocytes with autosomal and/or XY univalents, tetravalents and with extra elements. The probable causes of the formation of univalents and tetravalents are discussed. The transmission of the cytogenetic effects of the chemicals from spermatogonia up to sperm was assessed at week 8 post-treatment from the morphology of sperm collected from vas. Quantitatively the transmission of such effects was found decreased substantially by the time the exposed spermatogonia became sperm. Still there was the occurrence of a few abnormal sperm at week 8 post-treatment. The probable causes of the quantitative decrease in the transmission of the effects from spermtogonia to sperm are discussed.

A topographic study of Helicobacter pylori density, distribution and associated gastritis

BACKGROUND AND AIMS

The topographic distribution and density of Helicobacter pylori and associated gastritis in the stomach were studied in order to determine which biopsy sites are likely to provide the maximum yield so as to reduce the fallacious results due to sampling error.

METHODS

Fifty patients with upper gastrointestinal symptoms were studied. Eleven gastric biopsies from predetermined sites were obtained and subjected to ultra-rapid urease test, imprint cytology and histology. Haematoxylin and eosin stain was used for defining gastritis and other associated histopathological details. Loeffler's methylene blue stain was used to confirm the presence of H. pylori in imprint smears and histological sections.

RESULTS

All 50 patients had H. pylori infection and evidence of chronic gastritis at one or more of the 11 biopsy sites. Maximum and minimum percentage positivity were observed at A3 (antral lesser curvature) and B4 (corpus greater curvature), respectively. Various sites in decreasing order of percentage positivity were A3 > A2 > A1 > A4 > B3 > B1 > A5 > B6 > B5 > B2 > B4. Among the biopsies obtained from the corpus, B3 (corpus lesser curvature) was the site with maximum positivity. A3 and B4 had a statistically significant difference in percentage positivity (P < 0.0001) for H. pylori and gastritis. The maximum and minimum density scores of H. pylori and gastritis were found in A3 and the B4, respectively. A3 had a significantly higher (P < 0.0001) mean density score than any other site in the stomach. The difference in the grading of H. pylori between A3 and B3 (sites of maximum positivity in antrum and corpus) was statistically significant (P < 0.0001). A statistically significant (P < 0.001) positive correlation between increasing grades of H. pylori and gastritis was observed at the site of maximum density. Eighty per cent of the patients had antral predominant gastritis and in 82%, H. pylori was predominantly observed in antral biopsies.

CONCLUSION

It is concluded that two biopsies taken from A3 are sufficient for confirmation of presence of H. pylori and associated gastritis for initiation of treatment. However, additional biopsies from B3 will help in deciding the topographic pattern of gastritis.

Cytogenetic toxicity of cisplatin in bone marrow cells of Swiss mice

The inorganic platinum compound cisplatin (CP) in Oncoplatin, an anticancer drug, as the test chemical and cyclophosphamide (CY) in Endoxan, another anticancer drug, as the positive control, were tested for their cytogenetic toxicity in bone marrow cells of Swiss mice. The end points selected were mitotic metaphase chromosomal aberration and mitotic index study at 24-hour post-treatment and micronucleus test at 30-hour post-treatment after a single intraperitoneal exposure. The doses of the chemicals tested were CP 2, 3 and 5 mg/kg and CY 40 mg/kg b.w. of mice. Each of the doses of CP induced a significant number of chromosomal aberrations, mostly chromatid breaks and fragments and a significant number of micronuclei. The mitotic index study indicated CP as nonmitotoxic. The female mice were found more sensitive to each of the doses of CP than the males by showing more chromosomal aberrations, a higher number of micronuclei and comparatively less percentages of dividing cells. CP was thus found to be highly clastogenic in bone marrow cells of Swiss mice.

Comparative genomics of the eukaryotes

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.

Overexpression of p53 protein in gallbladder carcinoma in North India

AIMS

p53 mutations are one of the most frequent genetic alterations in human cancers and are thought to play a role in pathogenesis of several malignancies. Overexpression of p53 in gallbladder cancer has not previously been reported from North India which has one of the highest incidence of this malignancy in the world. The present work is aimed at studying the overexpression of p53 in gallbladder carcinoma occurring in North India.

METHODS

p53 overexpression by immunohistochemistry was studied in 20 operative specimens of gallbladder carcinoma. The clinico-pathological observations of these patients were correlated with the extent of p53 overexpression.

RESULTS

Seventy per cent (14/20) of specimens of gallbladder carcinoma overexpressed p53 protein. There was a significant correlation between presence of gallstones, T stage, grade of tumour and liver invasion with p53 overexpression. There was no significant correlation with other factors studied viz. age, sex, nodal status and histological type.

CONCLUSIONS

The results show a strong association between gallstones and p53 protein overexpression in gallbladder carcinoma. The causal relationship in this association, however, still remains unproven.

Altered diurnal regulation of blood ionized calcium and serum parathyroid hormone concentrations during parenteral nutrition

BACKGROUND

Little is known about parathyroid gland function in patients receiving total parenteral nutrition (TPN).

OBJECTIVE

Our objective was to determine whether parathyroid gland function is abnormal in TPN recipients.

DESIGN

Six patients with a mean (+/-1 SD) age of 45.5 +/- 8.0 y who had been receiving TPN for 18.7 +/- 2. 8 y underwent bone biopsy, bone mass measurements with dual-energy X-ray absorptiometry, and dynamic tests of parathyroid gland function. Diurnal variations in blood ionized calcium (iCa(2+)) and serum parathyroid hormone (PTH) concentrations were also assessed. Results were compared with those of healthy volunteers.

RESULTS

Bone mass and bone formation were subnormal in all patients. Basal serum PTH concentrations were moderately higher in the TPN recipients than in healthy volunteers, and values obtained every 30 min over 24 h were significantly higher (P < 0.001) in TPN recipients (5.0 +/- 0.9 pmol/L) than in healthy volunteers (2.6 +/- 0.6 pmol/L). The percentage increase in serum PTH during citrate-induced hypocalcemia was lower in the TPN recipients, consistent with secondary hyperparathyroidism. Evening infusions of calcium-containing TPN eliminated the nocturnal rise in serum PTH, increased the amplitude of change for iCa(2+) and PTH over 24 h, increased the orderliness of change for iCa(2+) and PTH as measured by approximate entropy (ApEn), and enhanced the synchrony of change between iCa(2+) and PTH. Treatment for 10 d with calcium-free TPN restored the nocturnal rise in serum PTH and increased ApEn for PTH. ApEn for iCa(2+) remained low, suggesting that a component of nutrient solutions, but not calcium per se, enhances the regularity of PTH release in TPN recipients.

CONCLUSION

Parathyroid gland function is abnormal in long-term TPN recipients, which may contribute to disturbances in bone metabolism.

Single-enhancing CT lesions in Indian patients with seizures: a review

Single enhancing CT lesions are the commonest radiological abnormality in Indian patients with new-onset partial seizures. In few patients the lesions may be 'tuberculoma' (especially in presence of evidence of tuberculosis elsewhere). However, histopathological studies have proved that neurocysticercosis is the most frequent cause for these lesions. Acute inflammation in and around the cerebral lesions of cysticercosis manifests as acute seizure disorder. These cysticercal granulomas represent 'colloidal' and 'nodular-granular' stages of Escobar's pathological classification of natural evolution of a parenchymal cysticercus cyst. In 8-12 weeks time majority of these lesions spontaneously disappear, few may calcify. As albendazole therapy is of controversial value, these patients, possibly, need to be treated only with antiepileptic drugs. Associated seizure disorder is also benign in nature and remit in majority within 6-8 months, recurrences are usually infrequent. Antiepileptic drug may be withdrawn once follow-up CT scan shows resolution of the lesion. If seizures recur after resolution of the lesion, CT lesion persists or CT lesion calcified, a long-term (2-3 years) antiepileptic therapy may be required. The single enhancing CT lesions which persist despite anticysticercal or antituberculous therapy may need histopathological evaluation to establish the correct diagnosis.