Monitoring of indoor volatile organic compounds and polycyclic aromatic hydrocarbons arising from kerosene cooking fuel

Air samples, representing indoor environments of a kitchen in which a kerosene stove was used were collected and analysed for volatile organic compounds (VOCs) viz., n-hexane, benzene, heptane, toluene, p- and o-xylene and n-decane using a cryogenic preconcentration system and a gas chromatograph with a flame-ionisation detector. Simultaneous outdoor samples were also collected to determine indoor to outdoor (I/O) ratios for each compound. Reversed phase high performance liquid chromatography (HPLC) with ultra violet absorption detection was optimised for separation and quantification of polycyclic aromatic hydrocarbons (PAHs) in air particulate matter. Concentration of total suspended particulate matter (TSPM), benzene soluble organics and the PAHs in air samples collected in indoor environment of some tenements at Trombay, Mumbai where kerosene is used as cooking fuel are discussed in relation to the concentration of the same in outdoor environment in vicinity of the tenement. VOCs and PAHs results from samples collected in kitchens in Trombay are discussed in relation to indoor air pollution.

Isolation and characterization of NADP+-linked isocitrate dehydrogenase of germinating pea seeds (Pisum sativum)

NADP+-linked isocitrate dehydrogenase (E.C.1.1.1.42) has been purified to homogeneity from germinating pea seeds. The enzyme is a tetrameric protein (mol wt, about 146,000) made up of apparently identical monomers (subunit mol wt, about 36,000). Thermal inactivation of purified enzyme at 45 degrees and 50 degrees C shows simple first order kinetics. The enzyme shows optimum activity at pH range 7.5-8. Effect of substrate [S] on enzyme activity at different pH (6.5-8) suggests that the proton behaves formally as an "uncompetitive inhibitor". A basic group of the enzyme (site) is protonated in this pH range in the presence of substrate only, with a pKa equal to 6.78. On successive dialysis against EDTA and phosphate buffer, pH 7.8 at 0 degrees C, yields an enzymatically inactive protein showing kinetics of thermal inactivation identical to the untreated (native) enzyme. Maximum enzyme activity is observed in presence of Mn2+ and Mg2+ ions (3.75 mM). Addition of Zn2+, Cd2+, Co2+ and Ca2+ ions brings about partial recovery. Other metal ions Fe2+, Cu2+ and Ni2+ are ineffective.

Pigeonpea (Cajanus cajan L.) urease immobilized on glutaraldehyde-activated chitosan beads and its analytical applications

Urease from pigeonpea (Cajanus cajan L.) was covalently linked to crab shell chitosan beads using glutaraldehyde. The optimum immobilization (64% activity) was observed at 4 degrees C, with a protein concentration of 0.24 mg/bead and 3% glutaraldehyde. The immobilized enzyme stored in 0.05 M Tris-acetate buffer, pH 7.3, at 4 degrees C had a t(1/2) of 110 d. There was practically no leaching of enzyme (<3%) from the immobilized beads in 30 d. The immobilized urease was used 10 times at an interval of 24 h between each use with 80% residual activity at the end of the period. The chitosan-immobilized urease showed a significantly higher Michaelis constant (8.3 mM) compared to that of the soluble urease (3.0 mM). Its apparent optimum pH also shifted from 7.3 to 8.5. Immobilized urease showed an optimal temperature of 77 degrees C, compared with 47 degrees C for the soluble urease. Time-dependent kinetics of the thermal denaturation of immobilized urease was studied and found to be monophasic in nature compared to biphasic in nature for soluble enzyme. This immobilized urease was used to analyze blood urea of some of the clinical samples from the clinical pathology laboratories. The results compared favorably with those obtained by the various chemical/biochemical methods employed in the clinical pathology laboratories. A column packed with immobilized urease beads was also prepared in a syringe for the regular and continuous monitoring of serum urea concentrations.

An endoplasmic reticulum protein implicated in chaperoning peptides to major histocompatibility of class I is an aminopeptidase

gp96, an abundant peptide-binding chaperone of the lumen of the endoplasmic reticulum and an acceptor of peptides transported into the endoplasmic reticulum through transporter associated with antigen processing, is shown to be an aminopeptidase. gp96 can trim an amino-terminal extended 19-mer precursor of the K(b)-binding VSV8 epitope for recognition by the cognate cytotoxic T lymphocyte clone. These observations support a role for gp96 in the amino-terminal trimming of extended peptides in the endoplasmic reticulum.

Characterization of gelatin-immobilized pigeonpea urease and preparation of a new urea biosensor

Urease purified from pigeonpea seeds was immobilized on gelatin beads via cross-linking with glutaraldehyde. The maximum immobilization (75%) was observed at 30 mg/ml gelatin, 0.414 mg of enzyme/bead, 1% (v/v) glutaraldehyde and 4 degrees C. Beads stored in 50 mM Tris/acetate buffer (pH 7.3) at 4 degrees C showed a half-life of 240 days and there was practically no leaching of enzyme (less than 2%) over a period of 30 days. These beads can be reused more than 30 times (with 24 h intervals) without much loss of enzyme activity (i.e. less than 11%). The immobilized urease showed a shift in its optimum pH from 7.3 to 6.5 in Tris/acetate buffer. Optimum temperature also shifted from 47 to 65 degrees C compared with the soluble enzyme. Gelatin-immobilized pigeonpea urease had a higher K(m) (8.3 mM) than that of the soluble enzyme (3.0 mM). The time-dependent temperature inactivation pattern was also found to change from biphasic to monophasic kinetics. The immobilized beads were used for the preparation of a new urea biosensor with a response time of less than 2 min. At least 14 samples of urea can be measured with this biosensor within an hour. The beads, as well as the biosensor, were used to analyse the urea content in clinical samples from the local clinical pathology laboratories. The results obtained with the biosensor were strikingly similar to those obtained with the various commonly employed biochemical/autoanalyzer(R) methods used. These immobilization studies also have a potential role in haemodialysis machines that maintain the urea level in kidney patients and in the construction of a portable/wearable kidney. The easy availability of the pigeonpea urease, the ease of its immobilization on gelatin and a significantly lower cost of the urease described in the present study makes it a suitable product for future applications in therapeutics and diagnostics.

Heat shock protein-chaperoned peptides but not free peptides introduced into the cytosol are presented efficiently by major histocompatibility complex I molecules

The studies reported here bear on the events in the cytosol that lead to trafficking of peptides during antigen processing and presentation by major histocompatibility complex (MHC) I molecules. We have introduced free antigenic peptides or antigenic peptides bound to serum albumin or to cytosolic heat shock proteins hsp90 (and its endoplasmic reticular homologue gp96) or hsp70 into the cytosol of living cells and have monitored the presentation of the peptides by appropriate MHC I molecules. The experiments show that (i) free peptides or serum albumin-bound peptides, introduced into the cytosol, become ligands of MHC I molecules at a far lower efficiency than peptides chaperoned by any of the heat shock proteins tested and (ii) treatment of cells with deoxyspergualin, a drug that binds hsp70 and hsp90 with apparent specificity, abrogates the ability of cells to present antigenic peptides through MHC I molecules, and introduction of additional hsp70 into the cytosol overcomes this abrogation. These results suggest for the first time a functional role for cytosolic chaperones in antigen processing.

Adjuvanticity of alpha 2-macroglobulin, an independent ligand for the heat shock protein receptor CD91

We recently have identified CD91 as a receptor for the heat shock protein gp96. CD91 was identified initially as a receptor for alpha(2)-macroglobulin (alpha(2)M). Gp96 and alpha(2)M are both ligands for CD91. Because gp96-chaperoned peptides can prime CD8(+) T cell responses and are re-presented by APCs, we tested alpha(2)M for similar properties. Our studies show that alpha(2)M binds peptides in vitro and that the peptides, chaperoned by alpha(2)M, efficiently prime peptide-specific CD8(+) T cell responses in mice immunized with alpha(2)M-peptide complexes. Furthermore, peptides chaperoned by alpha(2)M, like those chaperoned by gp96, can be re-presented by CD91(+) APCs on their MHC I molecules. These studies demonstrate that alpha(2)M molecules, like the heat shock protein molecules, are T cell adjuvants that can channel exogenous Ags into the endogenous pathway of Ag presentaion. The remarkable similarities between an intracellular chaperone and an extracellular serum chaperone may have interesting physiological ramifications.

Identification of a tumor-associated contact-dependent activity which reversibly downregulates cytolytic function of CD8+ T cells

Tumors elicit an immune response in hosts and yet, paradoxically, often grow progressively with fatal consequences. This phenomenon has been attributed to the possible expression by tumor cells of immunomodulatory factors that overcome the anti-tumor effector functions of both specific and non-specific immune cells. This study reports on the ability of the methylcholanthrene-induced fibrosarcoma, Meth A, as well as other tumors of varied histological origins to downregulate the lytic activity of CD8+ T cells. The suppressive activity is contact-dependent and reversible. As tumor-bearing hosts are rarely immunosuppressed systemically, these findings may explain how local events within the tumor bed subvert the specific anti-tumor immune response.

The immunoprotective MHC II epitope of a chemically induced tumor harbors a unique mutation in a ribosomal protein

CD4(+) T lymphocyte clones, generated from mice immunized with the methylcholanthrene-induced fibrosarcoma Meth A (H-2(d)), are restricted by I-E(d) and recognize a unique antigen on Meth A. The antigen has been purified and characterized as the ribosomal protein L11. The antigenic epitope is contained within the sequence EYELRKHNFSDTG and is generated by substitution of Asn by His (italic) caused by a single point mutation. The tumor contains the wild-type and the mutated alleles. Immunization of BALB/cJ mice with the mutated epitope but not with the wild-type epitope protects mice against a subsequent challenge with the Meth A sarcoma. Adoptive transfer of CD4(+) clones into BALB/c mice renders the mice specifically resistant to Meth A sarcoma. The mutated L11 epitope is thus shown to be an immunoprotective epitope in vivo by several criteria.

Heat shock proteins: the 'Swiss Army Knife' vaccines against cancers and infectious agents

The ability of heat shock proteins to: (a) chaperone peptides, including antigenic peptides; (b) interact with antigen presenting cells through a receptor; (c) stimulate antigen presenting cells to secrete inflammatory cytokines; and (d) mediate maturation of dendritic cells, makes them a one-stop shop for the immune system. These properties also permit the utilization of heat shock proteins for development of a new generation of prophylactic and therapeutic vaccines against cancers and infectious diseases.

Heat shock proteins: the fountainhead of innate and adaptive immune responses

The ability of heat shock proteins to (1) chaperone peptides, including antigenic peptides; (2) interact with antigen-presenting cells through a receptor; (3) stimulate antigen-presenting cells to secrete inflammatory cytokines; and (4) mediate maturation of dendritic cells, makes them a unique starting point for generation of immune responses. These properties also permit the use of heat shock proteins for development of a new generation of prophylactic and therapeutic vaccines against cancers and infectious diseases.

CD91 is a common receptor for heat shock proteins gp96, hsp90, hsp70, and calreticulin

Complexes of the heat shock protein gp96 and antigenic peptides are taken up by antigen-presenting cells and presented by MHC class I molecules. In order to explain the unusual efficiency of this process, the uptake of gp96 had been postulated to occur through a receptor, identified recently as CD91. We show here that complexes of peptides with heat shock proteins hsp90, calreticulin, and hsp70 are also taken up by macrophages and dendritic cells and re-presented by MHC class I molecules. All heat shock proteins utilize the CD91 receptor, even though some of the proteins have no homology with each other. Postuptake processing of gp96-chaperoned peptides requires proteasomes and the transporters associated with antigen processing, utilizing the classical endogenous antigen presentation pathway.

Cutting edge: heat shock protein gp96 induces maturation and migration of CD11c+ cells in vivo

Immunization of mice with the heat shock protein (HSP) gp96 but not control proteins leads to 5- to 7-fold enlargement of draining lymph nodes (LNs) resulting from accumulation of large numbers of mature CD11c(+) cells, but not T or B lymphocytes in them. The increase in size and cellularity is time-dependent; the draining LNs reach their peak size between 12 and 24 h after injection and regress to their normal size between 48 and 72 h after injection. The increment is elicited specifically in the draining LN but not in other LNs. This observation uncovers a novel aspect of HSP-APC interaction and adds to the mechanistic explanation for the unusually high immunogenicity of HSP-peptide complexes.

Immunization of cancer patients with autologous cancer-derived heat shock protein gp96 preparations: a pilot study

Heat shock protein (HSP)-peptide complexes isolated from murine cancers elicit protective immunity and T lymphocytes specific for the cancer from which the HSPs are isolated. A pilot study was designed to test the feasibility, immunogenicity and toxicity of such treatment in cancer patients. Sixteen patients with assorted advanced malignancies, which had become refractory to established therapies, were recruited. The gp96 vaccine was prepared for each patient from tumor obtained from that patient. Anti-tumor immune responses were evaluated using Elispot assays of T cells in peripheral blood after minimal in vitro stimulation. No unacceptable vaccine-related toxicities or auto-immune reactions were observed. Immunization with autologous gp96 elicited MHC I-restricted, tumor-specific CD8(+) T lymphocytes in 6/12 patients immunized. In addition, expansion of the NK cell population was seen in 8/13 of patients immunized. These observations are entirely consistent with the murine experience and form a firm basis for future trials with clinical end points, using autologous, patient-specific HSP-peptide vaccines.

Immunization of cancer patients with autologous cancer-derived heat shock protein gp96 preparations: a pilot study

Heat shock protein (HSP)-peptide complexes isolated from murine cancers elicit protective immunity and T lymphocytes specific for the cancer from which the HSPs are isolated. A pilot study was designed to test the feasibility, immunogenicity and toxicity of such treatment in cancer patients. Sixteen patients with assorted advanced malignancies, which had become refractory to established therapies, were recruited. The gp96 vaccine was prepared for each patient from tumor obtained from that patient. Anti-tumor immune responses were evaluated using Elispot assays of T cells in peripheral blood after minimal in vitro stimulation. No unacceptable vaccine-related toxicities or auto-immune reactions were observed. Immunization with autologous gp96 elicited MHC I-restricted, tumor-specific CD8(+) T lymphocytes in 6/12 patients immunized. In addition, expansion of the NK cell population was seen in 8/13 of patients immunized. These observations are entirely consistent with the murine experience and form a firm basis for future trials with clinical end points, using autologous, patient-specific HSP-peptide vaccines.

Natural autoantibodies against heat-shock proteins hsp70 and gp96: implications for immunotherapy using heat-shock proteins

Immunization of mice with cognate cancer-derived heat-shock protein (hsp) preparations leads to protection from cancer growth. As hsp used for vaccination or therapy are derived from autologous cancers, questions of pathological autoimmunity are of immense significance for the ongoing translation of this approach to therapy of human cancer. Employing the sera of normal adult mice as the first antibody, highly sensitive immunoblotting revealed the presence of anti-hsp natural autoantibodies in healthy animals. Natural autoantibodies of the immunoglobulin D (IgD) isotype bind to gp96, whereas hsp70 was recognized by IgD and IgM autoantibodies. Neither hsp was recognized by the IgA, IgE or IgG immunoglobulins contained in the serum. The antigen-antibody recognition was titratable and dependent on the integrity of the IgD molecule. Sera from only a subset of the animals tested were found to be positive for autoantibodies against gp96 and hsp70, and individual and strain-specific variations were detected. Injection of gp96 into healthy mice did not show sustained or consistent anti-gp96 IgD antibody response, class switching, toxicity or pathological autoimmunity. IgD autoantibodies against gp96 and hsp70 were also not detected in the autoimmune lpr mice. These observations show the existence of a measured and tightly regulated natural immune response to hsp.

Heat shock protein-based novel immunotherapies

The ability of heat shock proteins to chaperone peptides, including antigenic peptides; to interact with antigen-presenting cells through a receptor; to stimulate antigen-presenting cells to secrete inflammatory cytokines; and to mediate maturation of dendritic cells makes them a unique starting point for generation of immune responses. These properties also permit the utilization of heat shock proteins for development of a new generation of prophylactic and therapeutic vaccines against cancers and infectious diseases.

Necrotic but not apoptotic cell death releases heat shock proteins, which deliver a partial maturation signal to dendritic cells and activate the NF-kappa B pathway

Dendritic cells (DC) are key components of innate and adaptive immune responses. The identity of endogenous signals that activate DC is a crucial and unresolved question. We report here that heat shock proteins (HSP), the most abundant and conserved mammalian molecules, constitute such an internal signal. Necrotic but not apoptotic cell death leads to release of HSP gp96, calreticulin, hsp90 and hsp70. HSP stimulate macrophages to secrete cytokines, and induce expression of antigen-presenting and co-stimulatory molecules on the DC. The HSP gp96 and hsp70 act differentially, and each induces some but not all molecules. HSP interact with these antigen-presenting cells through the highly conserved NF-kappa B pathway. As HSP are intracellular, abundant and soluble, their presence in the extra-cellular milieu and the consequent activation of antigen-presenting cells (APC) constitutes an excellent mechanism for response to cell death. As HSP are conserved from bacteria to mammals, the ability of HSP to activate APC provides a unified mechanism for response to internal and external stimuli.

Significance of sulfhydryl groups in the activity of urease from pigeonpea (Cajanus cajan L.) seeds

Titration of urease from pigeonpea (Cajanus cajan L.), a hexameric protein (mol. wt. 480000; subunit mol. wt. 80000), with 5,5'-dithiobis-(2-nitrobenzoate) (DTNB) reveals the presence of 5.82+/-0.13 'accessible' sulfhydryl groups per molecule of the enzyme protein (i.e. about one 'accessible' SH group per subunit). Denatured enzyme was found to titrate for 12.1+/-0.1 SH groups per molecule (i.e. about two SH groups per subunit). Half of the 'accessible' groups react faster than the remaining at pH 8.5 as well as pH 7.5. However, the reaction was slower at pH 7.5 than 8.5. Time-dependent loss of enzyme activity with DTNB was also found to be biphasic. The enzyme was inactivated at low concentration of p-chloromercuribenzoate (p-CMB), N-ethyl maleimide (NEM) and iodoacetamide. The inactivation reactions were biphasic, with half of the activity lost more rapidly than the remaining half. The loss of activity with p-CMB was linearly related to the blocking of accessible SH groups. Inactivation by p-CMB is largely reversible by addition of excess of cysteine. Fluoride ion strongly protects the enzyme against NEM inactivation, however, substrate urea provides much weaker protection against SH group reagents. The significance of these results is discussed.

Immunization of cancer patients with autologous cancer-derived heat shock protein gp96 preparations: a pilot study

Heat shock protein (HSP)-peptide complexes isolated from murine cancers elicit protective immunity and T lymphocytes specific for the cancer from which the HSPs are isolated. A pilot study was designed to test the feasibility, immunogenicity and toxicity of such treatment in cancer patients. Sixteen patients with assorted advanced malignancies, which had become refractory to established therapies, were recruited. The gp96 vaccine was prepared for each patient from tumor obtained from that patient. Anti-tumor immune responses were evaluated using Elispot assays of T cells in peripheral blood after minimal in vitro stimulation. No unacceptable vaccine-related toxicities or auto-immune reactions were observed. Immunization with autologous gp96 elicited MHC I-restricted, tumor-specific CD8(+) T lymphocytes in 6/12 patients immunized. In addition, expansion of the NK cell population was seen in 8/13 of patients immunized. These observations are entirely consistent with the murine experience and form a firm basis for future trials with clinical end points, using autologous, patient-specific HSP-peptide vaccines.