Portal hypertension in north Indian children

Etiological factors associated with portal hypertension in children influence the decision about therapy and the prognosis. This cross-sectional observational study was performed at a tertiary care centre in northern India from January, 1990 to December, 1994. Children below the age of 14 years with suspected portal hypertension were prospectively assembled into a cohort to determine the etiology and clinical profile of portal hypertension. Of the 115 patients with portal hypertension, 76.5% had extrahepatic portal hypertension (EHPH). Remaining 23.5% of the cases had intrahepatic and post-hepatic causes of portal hypertension. Children with EHPH had a significantly earlier onset of symptoms as compared to those with intrahepatic portal hypertension (p = 0.002) and bled significantly more frequently (p = 0.00). Forty per cent of patients with chronic liver disease (CLD) never had jaundice. History suggestive of potential etiological factors could be elicited in only 7% of EHPH patients. The commonest site of block in splenoportal axis was at the formation of the portal vein. An inverse relation of bleeding rates with duration of illness was seen in EHPH. Of the 10 CLD patients in whom liver biopsy could be done, cirrhosis was present in 6 patients. Understanding the natural history of EHPH and portal hypertension due to other etiologies may have significant implications in choosing the appropriate intervention and predicting the outcome.

Liposome entrapped allergen reduces plasma histamine in sensitized mice

Immunotherapy of allergic diseases is associated with problems of adverse systemic reactions. We have shown earlier that liposome entrapped allergen (LEA) is effective in inducing IgG response and restricting IgE response in immunized mice. This mode of treatment may be more effective and safer if it can prevent anaphylaxis. To determine this feature, mice were administered allergen preparations repeatedly and later challenged with the same allergen. Mice given liposomal preparation showed lower specific IgE response as compared to the mice given free allergen or alum adsorbed allergen of Artemisia scoparia. Specific IgG response was higher in mice immunized with LEA. The mice immunized with liposomal preparation survived whereas others injected with free allergen or alum adsorbed allergen died probably due to anaphylaxis. High levels of histamine were observed in mice injected with free allergen as compared to the mice injected LEA. The increase in plasma histamine level may be the cause of anaphylaxis during allergen challenge. In conclusion, LEA could be used as a safe and effective mode of immunotherapy for allergy diseases, since it reduces plasma histamine levels considerably thereby reducing the chances of anaphylaxis.

Site directed mutagenesis of histidine residues in anthrax toxin lethal factor binding domain reduces toxicity

Anthrax lethal toxin is a mixture of protective antigen (PA, 735 AA) and lethal factor (LF, 776 AA). Earlier studies have shown that 254 residues of lethal factor are sufficient for PA binding to cause internalization (Arora N and Leppla SH, J Biol Chem 268: 3334-3342, 1993). The present study was undertaken to determine residues which are important for binding of LF to PA. LF modification with diethyl pyrocarbonate (DEPC, modifies histidine residue primarily) results in the loss of binding and toxicity in mammalian cells. There are nine histidine residues in the binding domain. To locate the important residue(s), site-directed mutagenesis of these histidines were performed by recombinant methods. Replacement of His42 with Gly42 destablizes the protein and hence it could not be purified. His35 when mutagenized to Gly35 (mLF-DTA) diminishes the toxicity by 20 fold. Time dependent studies show that binding of mLF-DTA was reduced at shorter incubations and longer incubations taper off this difference. Gel shift assay suggested 8-10% less binding of mLF-DTA as compared to LF-DTA. In conclusion His35 is important for binding and His42 is critical and confers proper conformation for LF binding to PA.

Targeting HIV proteins to the major histocompatibility complex class I processing pathway with a novel gp120-anthrax toxin fusion protein

A challenge for subunit vaccines whose goal is to elicit CD8(+) cytotoxic T lymphocytes (CTLs) is to deliver the antigen to the cytosol of the living cell, where it can be processed for presentation by major histocompatibility complex (MHC) class I molecules. Several bacterial toxins have evolved to efficiently deliver catalytic protein moieties to the cytosol of eukaryotic cells. Anthrax lethal toxin consists of two distinct proteins that combine to form the active toxin. Protective antigen (PA) binds to cells and is instrumental in delivering lethal factor (LF) to the cell cytosol. To test whether the lethal factor protein could be exploited for delivery of exogenous proteins to the MHC class I processing pathway, we constructed a genetic fusion between the amino-terminal 254 aa of LF and the gp120 portion of the HIV-1 envelope protein. Cells treated with this fusion protein (LF254-gp120) in the presence of PA effectively processed gp120 and presented an epitope recognized by HIV-1 gp120 V3-specific CTL. In contrast, when cells were treated with the LF254-gp120 fusion protein and a mutant PA protein defective for translocation, the cells were not able to present the epitope and were not lysed by the specific CTL. The entry into the cytosol and dependence on the classical cytosolic MHC class I pathway were confirmed by showing that antigen presentation by PA + LF254-gp120 was blocked by the proteasome inhibitor lactacystin. These data demonstrate the ability of the LF amino-terminal fragment to deliver antigens to the MHC class I pathway and provide the basis for the development of novel T cell vaccines.

Ribonuclease activity dependent cytotoxicity of Asp fl, a major allergen of A. fumigatus

A major allergen/antigen, Asp fl, secreted by Aspergillus fumigatus exhibits cytotoxicity towards eukaryotic cell lines. Asp fl inhibited protein synthesis in RAW cells with an IC50 of 4.5 nM and also degraded ribosomal RNA of RAW cells at a similar concentration. Ribosomal inactivation by Asp fl may be the probable mechanism for protein synthesis inhibition. Specific ribonuclease activity of Asp fl was observed to be 100,000 U/mg. Presence of strong RNase activity in Asp fl was further confirmed by agar gels containing yeast RNA. Electrophoretic run on agarose gels showed that Asp fl degrades all species of naked RNA. Modification of histidine residues of Asp fl with diethyl pyrocarbonate and alkylation of cysteines with iodoacetamide resulted in loss of ribonuclease activity and cytotoxicity of Asp fl. The current study establishes the ribonuclease activity of a purified major allergen of A. fumigatus that inhibits protein synthesis and kills the eukaryotic cells.

Identification and evaluation of a major cytotoxin of A. fumigatus

Aspergillus fumigatus is a highly pathogenic fungus causing a wide spectrum of diseases in immunocompromised as well as immunocompetent hosts. The present work was undertaken to evaluate the cytotoxic nature of fractionated antigens of A. fumigatus against the mammalian cell lines (J774, RAW, CHO and L929). An enriched protein antigenic fraction of A. fumigatus was subjected to con A Sepharose and phenyl Sepharose chromatography. Antigenic fractions, ConAub (conA unbound) and PSC III (fraction III of phenyl Sepharose column) containing low mw antigens showed higher cytotoxicity as compared to other antigenic fractions. PSC III was further purified on HPLC resulting in an 18 kDa homogeneous protein. The purified protein showed high ELISA absorbance values for specific IgG and IgE antibodies in sera of ABPA patients. Monoclonal antibody raised against Asp fl, a major allergen/antigen of A. fumigatus recognised the purified 18 kDa by ELISA and western blot. The 18 kDa allergen/antigen or Asp fl showed similar toxicity towards all the four cell lines (macrophage and fibroblast) with an IC50 of 75 ng/ml or 4.16 nM. Reduction in toxicity of 18 kDa at low temperatures and potentiation in presence of ammonium chloride and monensin indicates mechanism of internalisation of 18 kDa in eukaryotic cells is similar to alpha-sarcin. The present work shows that the 18 kDa allergen/antigen (Asp fl) is a major cytotoxin secreted by A. fumigatus which may play multiple roles in the pathogenesis of Aspergillosis through allergenicity, antigenicity and cytotoxicity.

Evidence for the shikimate-3-phosphate interacting site in the N-terminal domain of 5-enolpyruvyl shikimate-3-phosphate synthase of Bacillus subtilis

The role of basic amino acid residues that are highly conserved in the N-terminal domain of 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPs) in the binding of the substrate, shikimate-3-phosphate, has been assessed. Lys 19 and Arg 24 in the Bacillus subtilis EPSPs were substituted by glutamic acid and aspartic acid residues respectively by site-directed mutagenesis. Native and the mutant proteins were expressed using a two-vector system and the expressed proteins were purified to near homogeniety. The replacement of either Lys 19 or Arg 24 with a negatively charged residue nearly completely abolished the enzyme activity. The kinetic characterization of the purified wild type and the mutant proteins revealed that the substitution of positively charged residues in the N-terminal domain (K19 and R24) results in reduced affinity for shikimate-3-phosphate (S3P). The results suggest the involvement of these residues in the binding of S3P during enzyme catalysis.

Argyrophilic nucleolar organizer regions in soft tissue tumors

Argyrophilic nucleolar organizer region (AgNOR) staining was employed on 51 apparently normal representative soft tissues, 53 benign soft tissues tumors and 52 malignant soft tissue tumors with an aim to study the sensitivity and specificity of method in differentiating between the benign and malignant soft tissue tumors. The mean AgNORs count in apparently normal fibrous tissue was 1.02, whereas it was 0.94 in adipose tissue, 1.14 in smooth muscle tissue, 1.115 in skeletal muscle tissue, 1.025 in blood vessels endothelial lining cells and 1.04 in nerve tissue. The mean AgNOR count was found to be higher in benign soft tissue tumors as compared to respective apparently normal soft tissue and was found to be statistically significant. The mean AgNOR count in soft tissue sarcomas was found to be higher as compared to both apparently normal soft tissue and benign soft tissue tumors. An increase AgNOR score in both benign and malignant soft tissue tumors as compared to apparently normal soft tissue indicates high proliferative activity. The neurofibrosarcoma showed low AgNOR count as compared to other soft tissues sarcomas. The fibrohistiocytic sarcoma, leiomyosarcoma and angiosarcoma showed a mean AgNOR score of 4 or more than four. The mean AgNOR score was found to increase with high grade of the tumor. The AgNOR staining is simple and useful method in estimating tumor cell proliferation thereby differentiating normal soft tissue from non-neoplastic proliferative growth, benign and malignant soft tissue tumors. It may help in differentiating fibromatosis from fibrosarcoma, dermatofibrosarcoma protuberans of low grade malignancy from high grade malignant fibrous histiocytoma and benign hemangiopericytoma from malignant hemangiopericytoma.

Point mutation of a conserved arginine (104) to lysine introduces hypersensitivity to inhibition by glyphosate in the 5-enolpyruvylshikimate-3-phosphate synthase of Bacillus subtilis

The role of a conserved arginine (R104) in the putative phosphoenol pyruvate binding region of 5-enolpyruvyl shikimate-3-phosphate synthase of Bacillus subtilis has been investigated. Employing site directed mutagenesis arginine was substituted by lysine or glutamine. Native and mutant proteins were expressed and purified to near homogeneity. Estimation of Michaelis and inhibitor constants of the native and mutant proteins exhibited altered substrate-inhibitor binding mode and constants. Mutation R104K hypersensitized the enzyme reaction to inhibition by glyphosate. The role of R104 in discriminating between glyphosate and phosphoenol pyruvate is discussed.

5-Enolpyruvylshikimate-3-phosphate synthase of Bacillus subtilis is an allosteric enzyme. Analysis of Arg24-->Asp, Pro105-->Ser and His385-->Lys mutations suggests a hidden phosphoenolpyruvate-binding site

5-Enolpyruvylshikimate-3-phosphate synthase of Bacillus subtilis has been cloned, expressed and purified to near homogeneity. Clustal alignment of the amino acid sequences from different bacteria revealed several conserved residues located in the N-terminal, middle and C-terminal domains. The role of conserved Arg24, Pro105, and His385 residues has been examined by site-directed mutagenesis. Steady-state kinetic analysis of the native synthase exhibited allosteric behaviour, a feature thought to be unique amongst bacterial and plant 5-enolpyruvylshikimate-3-phosphate synthase enzymes investigated so far. Both substrates, phosphoenolpyruvate (P-pyruvate) and shikimate 3-phosphate have multiple interaction sites. There are two sites for P-pyruvate binding, catalytic and non-catalytic. Glyphosate (N-phosphonomethyl glycine) competes for binding at the catalytic site and does not interact at the secondary site. Glyphosate in the absence of ammonium ions increases cooperativity of P-pyruvate binding and favors dimerization of the enzyme through an interaction between P-pyruvate-binding sites. The ammonium-ion-activated 5-enolpyruvylshikimate-3-phosphate synthase displays no cooperativity with respect to P-pyruvate. Absence of ammonium ions decreases affinity for substrates and introduces cooperativity. Cooperativity was also introduced in the enzyme by point mutations, Arg24-->Asp and His385-->Lys. The latter mutant of the native enzyme exists as a dimer and aggregates to a tetrameric form in the presence of glyphosate. The occurrence of multimeric forms of the synthase has been demonstrated by staining for the enzyme activity on the native gel and by resolving purified enzyme preparations on a sucrose density gradient. A model describing the alteration in the aggregation status of the enzyme by the inhibitor, activator and the substrates has been proposed.

Proteolytic activation of bacterial toxins by eukaryotic cells is performed by furin and by additional cellular proteases

Before intoxication can occur, anthrax toxin protective antigen (PA), Pseudomonas exotoxin A (PE), and diphtheria toxin (DT) must be activated by proteolytic cleavage at specific amino acid sequences. Previously, it was shown that PA and DT can be activated by furin. In Chinese hamster ovary (CHO) cells, wild-type (RKKR) and cleavage site mutants of PA, each administered with a modified form of anthrax toxin lethal factor (the N terminus of lethal factor fused to PE domain III), had the following potencies: RKKR (wild type) (concentration causing 50% cell death [EC50] = 12 ng/ml) > or = RAAR (EC50 = 18 ng/ml) > FTKR (EC50 = 24 ng/ml) > STRR (EC50 = 49 ng/ml). In vitro cleavage of PA and cleavage site mutants of PA by furin demonstrated that native PA (RKKR) and PA with the cleavage sequence RAAR are substrates for furin. To characterize eukaryotic proteases that play a role in activating bacterial toxins, furin-deficient CHO cells were selected after chemical mutagenesis. Furin-deficient cells were resistant to PE, whose cleavage site, RQPR, constitutes a furin recognition site and to all PA cleavage site mutants, but were sensitive to DT (EC50 = 2.9 ng/ml) and PA (EC50 = 23 ng/ml), whose respective cleavage sites, RKKR and RVRR, contain additional basic residues. Furin-deficient cells that were transfected with the furin gene regained sensitivity to PE and PA cleavage site mutants. These studies provide evidence that furin can activate the three toxins and that one or more additional proteases contribute to the activation of DT and PA.

The chymotrypsin-sensitive site, FFD315, in anthrax toxin protective antigen is required for translocation of lethal factor

The protective antigen (PA) component of anthrax toxin contains two sites that are uniquely sensitive to proteolytic cleavage. Cleavage at the sequence RKKR167 by the cellular protease furin is absolutely required for toxicity, whereas cleavage by chymotrypsin or thermolysin at the sequence FFD315 inactivates the protein, apparently by blocking the ability of PA to translocate the catalytic moieties of the toxins, lethal factor (LF) and edema factor (EF), to the cytosol of eukaryotic cells. To specify the role of the chymotrypsin-sensitive site of PA in the translocation of LF, we altered residues 313-315. None of the mutations in this region interfered with the ability of PA to bind to its cellular receptor, be cleaved by cell surface furin, and bind LF. Substitution of Ala for Asp315 or for both Phe313 and Phe314 reduced the ability of PA to intoxicate cells in the presence of LF by 3- and 7-fold, respectively. Substitution of Phe313 by Cys greatly reduced the rate of LF translocation and delayed toxicity. The rate at which the Cys-substituted PA killed cells was increased significantly by blocking the sulfhydryl group with iodoacetamide, suggesting that this added Cys interacts with cellular proteins and slows translocation of LF. Deletion of the 2 Phe rendered PA completely non-toxic. This deleted PA protein lacked the ability shown by native PA to form oligomers on cells and in solution and to induce release of 86Rb from Chinese hamster ovary cells. These results suggest that the chymotrypsin-sensitive site in PA is required for membrane channel formation and translocation of LF into the cytosol. PA double mutants were constructed that cannot be cleaved at either the furin or chymotrypsin sites. These PA proteins were more stable in Bacillus anthracis culture supernatants and may therefore be useful as a replacement for PA in anthrax vaccines.

Fusions of anthrax toxin lethal factor with shiga toxin and diphtheria toxin enzymatic domains are toxic to mammalian cells

To investigate the ability of anthrax toxin lethal factor (LF) to translocate foreign proteins into the cytosol of eukaryotic cells and to characterize the structural requirements of this process, fusion proteins containing a portion of LF and the catalytic domains of either diphtheria toxin or Shiga toxin were constructed. Previous work showed that residues 1 to 254 of anthrax toxin lethal factor (LF1-254) are sufficient for binding to the protective antigen component of the toxin and that portions of Pseudomonas exotoxin A fused to LF1-254 are efficiently translocated to the cytosol of eukaryotic cells (N. Arora and S. H. Leppla, J. Biol. Chem. 268:3334-3341, 1993). In this study, it was found that fusion proteins containing the ADP-ribosylation domain of diphtheria toxin fused at either the amino end or the carboxyl end of LF1-254 are highly toxic to Chinese hamster ovary (CHO) cells, indicating that translocation does not strictly require that the amino terminus of LF be free. A fusion protein containing the ribosome-inactivating A1 subunit of Shiga toxin fused to the carboxyl terminus of LF1-254 was also highly toxic for CHO cells. All fusion proteins were toxic only when administered with the anthrax toxin protective antigen component. The data show that the combination of protective antigen and LF fusion proteins can efficiently import polypeptides from diverse bacterial sources to the cytosol of eukaryotic cells and that LF fusion proteins may have the passenger polypeptides fused at either the amino terminus or the carboxyl terminus of LF1-254. These LF fusion proteins could potentially be used as components of a therapeutic agent when the destruction of certain types of cells is desired (e.g., in treating cancer).

Cytotoxic effects of a chimeric protein consisting of tetanus toxin light chain and anthrax toxin lethal factor in non-neuronal cells

The light chain of tetanus toxin is a zinc endoprotease that inhibits neurotransmitter release by selective proteolysis of the synaptic vesicle-associated protein synaptobrevin/vesicle-associated membrane protein. Cellubrevin is a homologue of synaptobrevin that is found in most cell types and is also a substrate for tetanus toxin. The lack of receptors for tetanus toxin on most cell types has made studies of tetanus toxin action in non-neuronal cells difficult. To characterize tetanus toxin effects in non-neuronal cells, a fusion protein consisting of the 254 amino-terminal amino acids of lethal factor (LF) of anthrax toxin and tetanus toxin light chain (LC) was prepared. This protein (LF-LC) inhibited evoked glycine release from primary spinal cord neurons at concentrations between 1.0 and 100 ng/ml. LF-LC was cytotoxic to RAW 264.7, ANA-1 cells (mouse macrophage cell lines), and Chinese hamster ovary cells in a dose-dependent manner. These effects required the presence of protective antigen, the receptor binding component of anthrax toxin. In contrast, LF-LC was not cytotoxic to RBL-2H3, Vero, or mouse hybridoma cell lines. Mutagenesis of conserved amino acids (His237 and Glu234) in the zinc-binding motif of LC resulted in fusion proteins having no biological activity. LF-LC did not inhibit regulated secretion of serotonin in RBL-2H3 cells or constitutive secretion in any non-neuronal cell lines as measured in several different assays. We suggest that the cytotoxic effects of LF-LC result from inhibition of a specific intracellular membrane fusion event mediated by cellubrevin.

Anthrax toxin lethal factor contains a zinc metalloprotease consensus sequence which is required for lethal toxin activity

Comparison of the anthrax toxin lethal factor (LF) amino acid sequence with sequences in the Swiss protein database revealed short regions of similarity with the consensus zinc-binding site, HEXXH, that is characteristic of metalloproteases. Several protease inhibitors, including bestatin and captopril, prevented intoxication of macrophages by lethal toxin. LF was fully inactivated by site-directed mutagenesis that substituted Ala for either of the residues (H-686 and H-690) implicated in zinc binding. Similarly, LF was inactivated by substitution of Cys for E-687, which is thought to be an essential part of the catalytic site. In contrast, replacement of E-720 and E-721 with Ala had no effect on LF activity. LF bound 65Zn both in solution and on protein blots. The 65Zn binding was reduced for several of the LF mutants. These data suggest that anthrax toxin LF is a zinc metallopeptidase, the catalytic function of which is responsible for the lethal activity observed in cultured cells and in animals.

Serum inorganic phosphate levels in experimental intestinal ischaemia

Serial serum inorganic phosphate estimates were done following production of experimental intestinal ischaemia in dogs by occlusion of superior mesenteric artery (10 dogs) or vein (10 dogs) and compared to phosphate values in control dogs (5 for each experimental group). Elevated phosphate values were seen within one hour after ischaemia. Elevation was more marked following arterial occlusion, becoming statistically significant within 2 hours. It is suggested that serum inorganic phosphate elevation can be used as important laboratory test in early diagnosis of acute intestinal ischaemia.

Residues 1-254 of anthrax toxin lethal factor are sufficient to cause cellular uptake of fused polypeptides

Anthrax lethal toxin is a complex of protective antigen (PA, 735 amino acids) and lethal factor (LF, 776 amino acids) that lyses certain eukaryotic cells. LF interacts with PA to gain access to the cytosol to assert its toxicity. The internalization of LF requires that PA bind to a specific membrane receptor and be cleaved by a cell-surface protease (probably furin), so as to expose a site on PA to which LF binds with high affinity. To localize LF functional domains, amino, carboxyl, and internal deletions of LF were made. Toxicity was eliminated by deletion of 40 and 47 residues from the amino and carboxyl termini, respectively. Similarly, deleting the first of the four imperfect repeats of 19 amino acids located at residues 308-383 made LF non-toxic, showing that this region is also essential for activity. To identify the minimum region of LF which is required for binding to PA, varying amino-terminal portions of LF were fused to the ADP-ribosylation domain of Pseudomonas exotoxin A. Fusion proteins containing residues 1-254 of LF were toxic when administered with PA, while those having only residues 1-198 of LF were inactive, showing that the PA-binding domain of LF lies within residues 1-254.

Immortalization of mouse bone marrow-derived mast cells with Ad12-SV40 virus

Mast cells arise in cultures of murine bone marrow in medium supplemented with interleukin-3 (IL-3). In the present study, we report the development of long-term mast cell lines from murine bone-marrow-derived cultured mast cells (BMCMC) following inoculation with adenovirus 12-simian virus 40 (Ad12-SV40) hybrid virus. One culture of Ad12-SV40 immortalized BMCMC (designated as MCP-5) was selected for further analysis. These transformed cells appear similar in morphology and histochemistry to the primary BMCMC from which they are derived and did not shed infectious virus into the culture supernatants. In addition, these cells synthesize predominantly chondroitin sulfate proteoglycans and contain histamine which is released following a physiologic stimulus. Limiting-dilution single-cell cloning produced five independent mast cell lines (MCP-5.1 to MCP-5.5). Southern blot analysis of genomic DNA isolated from these single-cell clones demonstrates different patterns of viral integration in all the five clones. All clones retain responsiveness to an exogenous source of IL-3 for growth and proliferation. Each single-cell clone also demonstrates a unique pattern of cytokine gene expression in response to calcium ionophore A23187 and phorbol-12-myristate-13-acetate. This suggests that within a culture of BMCMC there are differences in cytokine gene expression that vary from one cell to another. The availability of immortalized mast cell lines derived from murine bone marrow which retain their growth factor responsiveness and the ability to respond to degranulating stimuli should facilitate future studies of mast cell biology.

Saliva-binding protein (SsaB) from Streptococcus sanguis 12 is a lipoprotein

Two lipoprotein consensus sequences (Leu-X-X-Cys) are found in the presumptive signal peptide region (positions 12 to 15 and 17 to 20) of saliva-binding protein (SsaB) from Streptococcus sanguis 12. Three analogs of SsaB containing Cys-->Gly mutations were constructed by site-directed mutagenesis of pSA2, the recombinant plasmid expressing SsaB. [3H]palmitate was incorporated into SsaB only when the native Cys-20 residue was present. These data show that SsaB is a lipoprotein and that Cys-20 is the critical site for acylation.

Passive cutaneous anaphylaxis in mouse skin is associated with local accumulation of interleukin-6 mRNA and immunoreactive interleukin-6 protein

We used a BALB/c model of passive cutaneous anaphylaxis (PCA), an IgE-mediated, mast cell-dependent reaction, to demonstrate the early production of the proinflammatory cytokine interleukin-6 (IL-6) mRNA and protein product. Northern blot analysis detects IL-6 mRNA 1, and 2 hours after antigen challenge (dinitrophenyl30-40 human serum albumin [DNP30-40-HSA]) and in situ hybridization reveals that it is primarily cells with round-to-oval nuclei within the dermis (1 to 3 per high-power field) expressing IL-6 mRNA. Immunohistochemistry revealed perinuclear and cytoplasmic staining for immunoreactive IL-6 in mononuclear dermal cells and also cells within the basal keratinocyte layer. Injection of recombinant murine IL-6 (rmIL-6) either systemically or locally during antidinitrophenyl IgE skin sensitization resulted in increased vasopermeability at the PCA site after DNP30-40-HSA. However, this increased permeability was not associated with a change in the character of the cellular infiltrate at the PCA site 8 hours later. Although the specific role of IL-6 in the generation of the allergic response remains unknown, its detection during PCA unequivocally demonstrates that IL-6 be considered one of the mediators identified in inflammation that follows allergic reactions.

Fusions of anthrax toxin lethal factor to the ADP-ribosylation domain of Pseudomonas exotoxin A are potent cytotoxins which are translocated to the cytosol of mammalian cells

The lethal factor (LF) and edema factor (EF) components of anthrax toxin are toxic to animal cells only if internalized by interaction with the protective antigen (PA) component. PA binds to a cell surface receptor and is proteolytically cleaved to expose a binding site for LF and EF. To study how LF and EF are internalized and trafficked within cells, LF was fused to the translocation and ADP-ribosylation domains (domains II and III, respectively) of Pseudomonas exotoxin A. LF fusion proteins containing Pseudomonas exotoxin A domains II and III were less toxic than those containing only domain III. Fusion proteins with a functional endoplasmic reticulum retention sequence, REDLK, at the carboxyl terminus of domain III were less toxic than those with a nonfunctional sequence, LDER. The most potent fusion protein, FP33, had an EC50 = 2 pM on Chinese hamster ovary cells, exceeding that of native Pseudomonas exotoxin A (EC50 = 420 pM). Toxicity of all the fusion proteins required the presence of PA and was blocked by monensin. These data suggest that LF and LF fusion proteins are efficiently translocated from acidified endosomes directly to the cytosol without trafficking through other organelles, as is required for Pseudomonas exotoxin A. This system provides a potential vehicle for importing diverse proteins into the cytosol of mammalian cells.

Evaluation of protein assay methods for pollen and fungal spore extracts

The usual procedures available for protein estimation of biological extracts often give variable results due to presence of many peptides and coloured materials. To identify a suitable method for allergenic extracts, protein was estimated from common pollen and fungal antigens by modified Lowry's (ML), Bradford (B), micro-Kjeldahl (MK), Bicinchoninic acid (BCA) and modified BCA (MBCA) assays. Bradford assay resulted in low protein values, whereas BCA method gave very high values in general. Statistical analysis of the results revealed similarity between protein values quantitated by MK, ML and MBCA methods for most of the extracts. Graded volumes of the extracts on subjecting to protein estimation by these three methods showed linear response, while recovery of a protein (bovine serum albumin) added to the extracts was greater than 90%.

A study on antigenic and allergenic changes during storage in three different biological extracts

The stability of three allergens common in tropical countries was evaluated under different storage conditions. Prosopis juliflora (PJ), Rhizopus nigricans (RN), and wheat dust (WD), were taken as representatives of various groups of allergens viz, pollen, fungi and dust. The extracts were stored in buffer containing phenol (0.4%) or glycerol (50%) at temperatures ranging from 4-55 degrees C for 15 to 60 days. Protein content of PJ extract was reduced remarkably when it was stored at 40 degrees C for 45 days. Thin layer isoelectric focusing and rocket immunoelectrophoresis of PJ showed that certain antigenic proteins degrade rapidly even at 25 degrees C as early as day 15. However, two to three proteins of PJ remain stable at a higher temperature (40 degrees C) for two months. Relative radioallergosorbent test (RAST) inhibition showed substantial loss of allergenic activity in all the three extracts, when stored at higher temperatures (25-55 degrees C) even for short durations, i.e., 15 days. Extracts (PJ and RN) containing 50% glycerol were found to be stable, retaining more than 50% activity, even when stored at 55 degrees C for 40 days, while extracts without glycerol lost more than 75% of their allergenic activity. However, addition of glycerol did not change the stability of wheat dust allergenic extract. The present findings indicate that allergenic extracts behave differently when stored. Hence, the stability of each extract should be determined individually.

Marked improvement in parameters of renal osteodystrophy with the use of intraperitoneal calcitriol

Parenteral administration of Calcitriol is felt to be superior to oral Calcitriol in the treatment of renal osteodystrophy in chronic renal failure patients. We analyzed the results of serum calcium, phosphorus, alkaline phosphatase, and N-terminal parathormone level which are the clinical parameters of renal osteodystrophy in twenty-three chronic peritoneal dialysis patients who received varying dosages of intraperitoneal Calcitriol. The results which were analyzed at the end of one to twenty-three months revealed significant increase in serum calcium and a significant decrease in the values of alkaline phosphatase and N-terminal parathormone level.

Efficacy of liposome entrapped allergen in down regulation of IgE response in mice

The effect of liposome entrapped allergen on primary, secondary and ongoing IgE response was studied in mice. It was observed that mice primed with liposome entrapped allergen maintained significantly lower levels of serum specific IgE as compared to that of controls primed with allergen. Although alum adsorbed allergen could induce IgE synthesis in mice primed with liposome entrapped allergen the increase in serum specific IgE levels was lower than the animals primed and challenged with alum adsorbed allergen. On the contrary when BALB/c mice were primed with alum adsorbed allergen to induce IgE synthesis subsequent challenge by liposome entrapped allergen could down regulate the serum specific IgE response. Serum specific IgG response did not show any significant difference between the two groups. There was an increase in T suppressor cell subpopulation as measured by immunofluorescence technique in mice injected liposome entrapped allergen as compared to that in controls. The results indicate that liposome entrapped allergens may prove to be safe and effective in immunotherapy by reducing the allergenic response of the allergen at the same time increasing the antigenicity.

Performance characteristics of contemporary hemodialysis and venovenous hemofiltration in acute renal failure

Modality choice in the treatment of acute renal failure (ARF) should be based on the match between individual patient needs and the characteristics of available therapies. Considerations include access, risk of bleeding, hemodynamic instability, and ability to remove excess volume. We prospectively studied 547 consecutive treatments for ARF in 110 patients to determine the performance features of modalities based on single-vessel venous access: hemodialysis (HD) and venovenous hemofiltration (VVH). All treatments were performed in an 18-month period at a single center. Patients' ages ranged from 16 to 84 years; 26 were trauma cases; 69 patients expired during their hospitalization. Mean number of treatments per patient was 4.97. Mean treatment duration was 197 min. Heparin was used unless active bleeding was present or felt to be a high risk; mean dose required was 2628 units. Pressor therapy was in progress prior to initiation of 260 (48%) of treatments.

RESULTS

pretreatment and posttreatment mean systolic and diastolic BP were unchanged for the group. Forty-three (7.9%) treatments were terminated prematurely; of these only 27 (4.9%) were due to hypotension. No patient developed clinically apparent bleeding during any treatment. Contemporary equipment and techniques allow for provision of high-quality intermittent therapy for ARF, with excellent hemodynamic stability. Shorter, single-vein access treatments are advantageous for severely ill or injured patients who often undergo invasive monitoring and multiple studies or procedures.

Liposomes as vehicle for allergen presentation in the immunotherapy of allergic diseases

Liposomes are non-toxic, biodegradable and weakly immunogenic lipid vesicles which can be used as immunomodulating agents. In the present study, multilamellar vesicles (MLV) and small unilamellar vesicles (SUV) were used to incorporate an allergenic protein from Artemisia scoparia pollen. MLV incorporated more allergenic protein than SUV. To assess the immunomodulating effect of allergen entrapped in liposomes, Swiss strain mice (made IgE responders) were injected with either free allergen or liposome-entrapped allergen (LEA) and their immune response was measured in terms of specific IgG and specific IgE levels. Results indicated that specific IgE response was significantly lower in mice injected LEA (P less than 0.02) than in mice injected free allergenic protein. Although specific IgG response was higher in mice injected LEA, there was no statistically significant difference between the two groups. Potential use of liposomes as non-immunogenic biocompatible vehicle for antigen presentation in immunotherapy will be discussed.

Sudden blindness associated with central nervous symptoms in a hemodialysis patient

Purtscher's-like retinopathy as a cause of sudden blindness in hemodialysis patients is not widely known. This is believed to occur secondary to leukoembolization to retinal arterioles following complement activation. We describe a patient who developed sudden but reversible loss of vision on hemodialysis associated with varying reversible neurological signs and symptoms which we felt may have been a manifestation of leukoembolic aggregates lodging in the arterioles of the retina and central nervous system circulations.

Immunomodulation by liposome entrapped allergen

Liposomes are non-toxic, biodegradable and feebly immunogenic lipid vesicles made from natural and synthetic lipids. They are known to act as immunopotentiating agents and can be used to formulate sustained release preparation by encapsulation. In the present study, liposome entrapped allergen and free allergen were used to inject in Balb/C mice at different time intervals and their immune response in terms of specific IgG and specific IgE levels was quantitated by ELISA (Enzyme Linked Immuno sorbent Assay). The results indicated that specific IgE response was significantly higher in mice injected free allergen as compared to that of mice given liposome entrapped allergen. However, the specific IgG response was not statistically significant. Experiments carried out with liposome entrapped allergen and liposome coupled allergen showed no statistically significant difference in specific IgE and specific IgG titre between the two groups of mice. This type of immunomodulatory effect of liposomes in reducing IgE levels and without affecting IgG levels may be useful in Type I allergic disorders.

Radio-active iodine uptake in vitiligo

Vitiligo and thyroid disease are commonly associated disorders. Twenty-two clinically euthyroid vitiligo patients were studied for functional assessment of thyroid by radioactive iodine uptake assay. Half of them showed abnormal uptake values at 24 hours. Of these patients, 90% had lower values indicating a tendency towards developing hypothyroid state. Subclinical thyroid dysfunction in vitiligo appears to be an adaptive change.

Allergens entrapped in liposomes reduce allergenicity and induce immunogenicity on repeated injections in mice

Liposomes which are nontoxic, biodegradable and biocompatible lipid vesicles are known to act as adjuvants and can be used to formulate sustained release preparation by encapsulation. In the present study, allergen entrapped in liposomes were injected at different time intervals in Swiss mice (made responders to IgE by injecting cyclophosphamide) and Balb/C mice (high IgE responders). Tissue distribution studies after intraperitoneal injection of allergen (entrapped and untrapped) revealed that liposome-entrapped allergen was retained for a longer time in all the tissues except kidney as compared to the free allergen given similarly. It was observed that serum specific IgG antibody levels were higher and specific IgE levels were lower in animals given repeated injections of liposomes-entrapped allergen as compared to those animals injected free allergen in the same manner. The entrapment of allergen in liposomes somehow suppressed the specific IgE response on repeated injections. The immunomodulatory effect of liposomes may be useful in the immunotherapy of respiratory allergic disorders.

Immunochemical characterization of cocos nucifera pollen

The Cocos nucifera pollen, as one of the sources of allergen responsible for immediate hypersensitivity reaction, was confirmed by skin prick test, bronchial provocation test, and RAST. The whole pollen extract (WPE) of C. nucifera was fractionated by combination of gel filtration and ion-exchange columns with fast protein liquid chromatography (Pharmacia, Uppsala, Sweden). Three protein peaks designated Cocos II, Cocos VI, and Cocos VII exhibited allergenic properties, as tested by skin prick test, direct IgE ELISA, bronchial provocation test, and immunoblot analysis. In RAST inhibition, Cocos IIa (a high-molecular-weight protein) obtained by fractionation of Cocos II on Mono Q column (fast protein liquid chromatography) (Pharmacia) was found to be the most potent allergen in Cocos WPE, followed by Cocos VI and Cocos VII, which are low-molecular-weight proteins. The reference patterns of Cocos WPE on crossed immunoelectrophoresis and thin-layer isoelectric focusing were established for future standardization of Cocos WPE to be used in the diagnosis and immunotherapy of allergic patients.

Effect of phenylbutazone on acute hemorrhagic pancreatitis in dogs

Experiments were conducted on 24 mongrel dogs to study the effect of phenylbutazone on acute experimental pancreatitis. Necrotico-hemorrhagic pancreatitis was produced by local infiltration of autologous bile. The severity of pancreatitis was assessed by biochemical estimation and histopathological examination. Pretreatment with phenylbutazone reduced the severity of pancreatitis, both biochemically and histologically (total score 6.0 +/- 1.52 in the test group vs 8.33 +/- 1.80 in the control group; p less than 0.01).

Impairments induced by sublethal doses of two pesticides in the ovaries of a freshwater teleost Channa striatus Bloch

Impairments induced by sublethal doses of two pesticides Carbaryl and Endosulfan have been studied on the ovaries of a freshwater teleost Channa striatus by exposing the fish for a period of 2 to 30 days during the spawning season. The pesticide exposure produced reduction in the number of oocytes, reduction in size and deformity in different stages of oocytes, damage to yolk vesicles in maturing and mature oocytes, increase in the number of atretic oocytes, development of interfollicular spaces, increase in the connective tissue of tunica albuginea, dilation of blood vessels and reduction in the gonadosomatic index. The histopathological effects were dependent on the dose, duration of exposure, and the type of pesticide. Sublethal doses of Endosulfan were more toxic than those of Carbaryl.