Learning in year-old female autoimmune BXSB mice

BXSB/ MpJ-Yaa and NZB/BINJ mice have been used as animal models for both developmental learning disability and systemic autoimmune disease. Approximately 40-60% of these animals show ectopic clusters of neurons in Layer I of cortex similar to those found in postmortem analyses of human dyslexics, and all exhibit an autoimmune condition similar to systemic lupus erythematosus (SLE) in humans. The expression of immune disease in the BXSB strain, unlike in humans, is more severe in males than females. Most previous studies have examined the behavioral sequelae of neocortical ectopias at a relatively young age, when the BXSB females (unlike the male BXSB and female and male NZBs) are not yet showing high titers of autoantibodies associated with their lupus-like form of autoimmune disease. This study examined the behavior of BXSB females at an age subsequent to autoimmune disease onset. When contrasted with younger animals, year-old BXSB females showed good learning behavior, with no differences in Lashley maze learning and remarkably good performance in a visual discrimination learning task. These results are consistent with other data which indicate that many types of learning behavior are apparently unperturbed by systemic autoimmune disease. Results also showed significant interactions between a measure of lateral paw preference and the presence or absence of ectopias in Lashley maze learning. Animals without ectopias that exhibited a right lateral paw preference showed the greatest number of errors on a number of test measures. These findings support previous results indicating that behavioral effects associated with ectopias may vary based upon the behavioral laterality of affected animals.

Mutations in the contact region between the alpha and beta subunits of tryptophan synthase alter subunit interaction and intersubunit communication

Interaction between the alpha and beta subunits of tryptophan synthase leads to mutual stabilization of the active conformations and to coordinated control of the activities of the two subunits. To elucidate the roles of specific residues in the interaction site between the alpha and beta subunits, mutant alpha and beta subunits were constructed, and the effects of mutation on subunit interaction and intersubunit communication were determined. Mutation of either alpha subunit Asp56 (alphaD56A) or beta subunit Lys167 (betaK167T), residues that interact in some crystal structures of the tryptophan synthase alpha2beta2 complex, decreases the ability of the alpha subunit to activate the beta subunit and alters the reaction and substrate specificity of the beta subunit. Partial conformational repair is provided by alpha-glycerol 3-phosphate, a ligand that binds to the alpha subunit, or by Cs+ or NH4+, ligands that bind to the beta subunit. Mutation of beta subunit Arg175 (betaR175A), a residue that interacts with alpha subunit Pro57 in some structures, has much smaller effects on activity but results in a 15-fold increase in the apparent Kd for dissociation of the alpha and beta subunits. Replacement of the single tryptophan in the beta subunit by phenylalanine (W177F) has only small effects on activity but increases the apparent subunit dissociation constant approximately 10-fold. The most important conclusions of this investigation are that interaction between alphaAsp56 and betaLys167 is important for intersubunit communication and that mutual stabilization of the active conformations of the two subunits is impaired by mutation of either residue.

A dye-based lymphocyte proliferation assay that permits multiple immunological analyses: mRNA, cytogenetic, apoptosis, and immunophenotyping studies

Alamar Blue in the microenvironment of activated cells, undergoes color change and also becomes fluorescent. By using the Alamar Blue dye, we have reported a non-radioactive colorimetric assay to indirectly determine proliferation of murine lymphocytes. We further show that the pattern of mitogen-induced proliferation assessed fluorometrically was comparable to the 3H-thymidine incorporation assay (3H-Tdr assay). Of practical importance is that the color/fluorescence changes were stable at 4 degrees C in the dark for 3-4 weeks. In immunological studies, it is important to further analyze lymphocytes that have undergone activation and/or proliferation. This is not possible with the standard 3H-Tdr assay, which requires lysis of cells. In contrast, the Alamar Blue-based non-radioactive assay does not require cell lysis. We therefore tested the hypothesis that further analysis of lymphocytes is possible, after assessing the proliferation using Alamar Blue. Following assessment of proliferation in a 72-h culture, the Alamar Blue dye was washed-off and cells were re-utilized to perform additional immunological analysis. Short-term exposure of lymphocytes to Alamar Blue was not detrimental to lymphocytes, as assessed by trypan blue exclusion and the propidium iodide (PI) assays. Exposure of dexamethasone-treated cells to Alamar Blue did not interfere with the performance of apoptosis assays, such as flow cytometric analysis of PI-stained cells and microscopic examination of ethidium bromide/acridine orange-stained cells. In addition, prior exposure of lymphocytes to Alamar Blue did not affect the analysis of chromosomal aberrations or the visualization of cell surface antigens by flow cytometry. Further, the expression of cytokine mRNA in lymphocytes previously exposed to Alamar Blue was similar to unexposed cells. Together, a notable advantage of this assay is that it now enables the investigator to maximize information by following or correlating proliferation with other immunologic events in the same cells.

Manipulation of behavioral disorders in autoimmune mice via prolactin

Autoimmune mice perform poorly in two-way active avoidance tasks, and the extent of this performance deficit appears to be related to the extent of autoimmunity following developmental manipulations. In the current study, the pituitary hormone prolactin, which has immune-enhancing effects, was used to manipulate this behavioral disorder in adulthood. Prolatinergic manipulation may be achieved by the use of dopaminergic drugs. In two experiments, autoimmune NZB X NZW F1 (BW) mice received either pimozide (PIM; a D2 antagonist) or bromocriptine (CB154; a dopamine agonist) in their drinking water. Control subjects received plain water. Following treatment, subjects were tested in an activity monitor, and active avoidance learning. Circulating PRL levels, as measured by RIA, were significantly increased by PIM and significantly decreased by CB154. Neither drug affected circulating levels of autoantibodies to DNA or cardiolipin, a phospholipid. In Experiment 1, in which mice were tested at 12 weeks of age, after 6 weeks of drug treatment, PIM treated animals of both sexes showed significantly more failures to escape the shock in avoidance conditioning, while CB154 did not have significant effects. In Experiment 2, in which mice were tested at 16 weeks of age, after 12 weeks of drug treatment, CB154 treated females (males were not tested) showed significantly fewer failures to escape, while PIM did not have significant effects. The effects of PRL on behavior, and its relation to immune system function, are discussed.

Dissociation equilibria of the tryptophan synthase alpha 2 beta 2 complex in saline buffer and guanidine isothiocyanate, as studied by sedimentation equilibrium

The dissociation equilibria of Salmonella typhimurium tryptophan synthase alpha 2 beta 2 complex were studied via centrifugation of the complex to sedimentation equilibrium in neutral saline buffers containing 0 to 137 mM guanidine isothiocyanate (GuSCN). The resulting concentration gradients were analyzed in the context of an equilibrium model for sequential dissociation of two alpha subunits from a stable beta 2 subunit. Under the conditions of these experiments, the first dissociation constant alone could be evaluated at GuSCN concentrations < or = 100 mM, and the second dissociation constant alone could be evaluated at GuSCN = 137 mM. At intermediate GuSCN, both dissociation constants were sufficiently well defined to rule out the presence of a large equilibrium cooperative effect in the stepwise dissociation of the alpha subunits.

Synthesis of some biologically active agents derived from thieno[2,3-d]pyrimidine derivatives

The key compound 1-amino-8-iminocyclopenta[b]thieno[2,3-d]pyrimidine (5g) was prepared by reaction of 2-amino-3-cyano cyclopenta[b]thiophene (1) with triethyl orthoformate followed by cyclization with hydrazine hydrate in ethanol. Refluxing of 1 with triethyl orthoformate in the presence of acetic anhydride gave an unexpected product 2. while reaction with aromatic amines gave the condensation products 4a-c. Reaction of 5g with formic acid, other formate derivatives, ethoxymethylenemalononitrile and ethyl ethoxymethylenecyanoacetate gave the same product cyclopentathieno-[2,3-d]-1,2,4-triazolo[3,2-f]pyrimidine 6. Compound 7 was prepared by different methods. Treatment of 5g with dicarbonyl compounds gave the triazol derivatives 8-11. Reaction of 5g with phenyl isothiocyanate, carbon disulphide and ethyl chloroformate gave the corresponding derivatives 12-14, respectively. Condensation of 5g with some selected aromatic and heterocyclic aldehydes, acetone, N-acetyl isatin and isatin gave the condensation products 15a-e, 16-18, respectively in good yields. Many of the synthesized compounds were tested in vitro for their inhibitory activity against a variety of bacteria such as: Serratia rhodnii, Bacillus cereus, Staphylococcus citreus and Pseudomonas aeruginosa and fungi such as: Aspergillus flavus, Penicillium chrysogenum and Alternaria alternarta. Some compounds showed modest activity.

Analysis of avian lymphocyte proliferation by a new, simple, nonradioactive assay (lympho-pro)

An assessment of T-cell-mediated immune functions (i.e., lymphocyte proliferation assay) in the chicken, unlike the determination of antibody levels, is not routinely performed. This is primarily because of difficulties in the isolation of relatively pure populations of lymphocytes and the use of radioactive isotopes. To address these issues, the goals of our study were to optimize a method for isolating and enriching avian lymphocyte populations and to develop a nonradioactive lymphocyte proliferation assay. To accomplish these goals, we used a multiple slow-speed centrifugation technique combined with a "swirl" collection technique for lymphocyte isolation from chicken peripheral blood. After a fraction enriched with lymphocytes was obtained, a simple, rapid colorimetric and fluorometric assay (lympho-pro) to indirectly determine mitogen-induced proliferation was adapted and compared with the "Gold Standard" [3H]thymidine. Chickens of different ages and two genetic strains were used in this study. Lymphocytes were stimulated with various concentrations of concanavalin A (Con A, T-cell mitogen) or phorbol 12-myristate 13-acetate + ionomycin (pan lymphocyte mitogen). Our studies showed that the pattern of lymphocyte proliferation assessed by the Alamar blue-based lympho-pro assay was similar to the [3H]thymidine incorporation assay. Younger birds had higher levels of mitogen-induced proliferation when compared with adults of the same genetic strain. Because the lympho-pro assay, unlike [3H]thymidine, does not require lysis of cells to assess proliferation, cells that have undergone stimulation/proliferation can be subsequently characterized by staining with antibodies against cell surface antigens and analysis by flow cytometry. Another notable advantage of the lympho-pro assay is the rapidity of assessment and nontoxicity. In conclusion, this assay may be of value in assessing some aspects of T-cell-mediated immunity in both avian research and avian medicine diagnostic settings.

Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes

Three-dimensional structures are reported for a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with either the substrate L-serine (betaK87T-Ser) or product L-tryptophan (betaK87T-Trp) at the active site of the beta-subunit, in which both amino acids form external aldimines with the coenzyme, pyridoxal phosphate. We also present structures with L-serine bound to the beta site and either alpha-glycerol 3-phosphate (betaK87T-Ser-GP) or indole-3-propanol phosphate (betaK87T-Ser-IPP) bound to the active site of the alpha-subunit. The results further identify the substrate and product binding sites in each subunit and provide insight into conformational changes that occur upon formation of these complexes. The two structures having ligands at the active sites of both alpha- and beta-subunits reveal an important new feature, the ordering of alpha-subunit loop 6 (residues 179-187). Closure of loop 6 isolates the active site of the alpha-subunit from solvent and results in interaction between alphaThr183 and the catalytic residue alphaAsp60. Other conformational differences between the wild type and these two mutant structures include a rigid-body rotation of the alpha-subunit of approximately 5 degrees relative to the beta-subunit and large movements of part of the beta-subunit (residues 93-189) toward the rest of the beta-subunit. Much smaller differences are observed in the betaK87T-Ser structure. Remarkably, binding of tryptophan to the beta active site results in conformational changes very similar to those observed in the betaK87T-Ser-GP and betaK87T-Ser-IPP structures, with exception of the disordered alpha-subunit loop 6. These large-scale changes, the closure of loop 6, and the movements of a small number of side chains in the alpha-beta interaction site provide a structural base for interpreting the allosteric properties of tryptophan synthase.

Importance of conserved and variable C-terminal residues for the activity and thermal stability of the beta subunit of tryptophan synthase

To assess the functional roles of helix 13 and of the conserved and variable residues in the C-terminal region (residues 378-397) of the tryptophan synthase beta subunit, we have constructed four C-terminal truncations and 12 point mutations. The effects of these mutations on kinetic and spectroscopic properties and thermal stability are reported here. The mutant beta subunits all form stable alpha2beta2 complexes that have been purified to homogeneity. The mutant alpha2beta2 complexes are divided into two classes on the basis of activity in the reaction of L-serine with indole to form tryptophan. Class I enzymes, which have mutations at Arg-379 or Asp-381 or truncations (384-397 or 385-397), exhibit significant activity (1-38% of wild type). Class II enzymes, which have mutations at Lys-382 or Asp-383 or truncations (382-397 or 383-397), exhibit very low activity (<1% of wild type). Although Class II enzymes have drastically reduced activity in the reaction of L-serine with indole and an altered distribution of enzyme-substrate intermediates in the reaction of L-serine with beta-mercaptoethanol, they retain activity in the reaction of beta-chloro-L-alanine with indole. Correlation of the results with the three-dimensional structure of the alpha2beta2 complex suggests that Lys-382 and Asp-383 serve important roles in a proposed "open" to "closed" conformational change that occurs in the reactions of L-serine. Because mutant beta subunits having C-terminal truncations (383-397 or 384-397) undergo much more rapid thermal inactivation at 60 degrees C than the wild type beta subunit, the C-terminal helix 13 stabilizes the beta subunit.

Mechanism of activation of the tryptophan synthase alpha2beta2 complex. Solvent effects of the co-substrate beta-mercaptoethanol

To characterize the conformational transitions that lead to activation of catalysis by the tryptophan synthase alpha2beta2 complex, we have determined the solvent effects of a co-substrate, beta-mercaptoethanol, and of a model nonsubstrate, ethanol, on the catalytic and spectroscopic properties of the enzyme. Our results show that ethanol and beta-mercaptoethanol both alter the equilibrium distribution of pyridoxal 5'-phosphate intermediates formed in the reactions of L-serine at the beta site in the alpha2beta2 complex. Addition of increasing concentrations of ethanol increases the proportion of the external aldimine of L-serine and decreases the proportion of the external aldimine of aminoacrylate. Low concentrations of the co-substrate beta-mercaptoethanol (Kd = approximately 13 mM) decrease the proportion of the external aldimine of aminoacrylate and induce formation of the quinonoid of S-hydroxyethyl-L-cysteine. Higher concentrations of beta-mercaptoethanol decrease the concentration of the quinonoid intermediate and increase the proportion of the external aldimine of L-serine. Data analysis shows that beta-mercaptoethanol and ethanol both interact or bind preferentially with the conformer of the enzyme that predominates when the aldimine of L-serine is formed and shift the equilibrium in favor of this conformer. We propose that a nonpolar region of the beta subunit, possibly the hydrophobic indole tunnel, becomes less exposed to solvent in the conformational transition that activates the alpha2beta2 complex.

Diagnostic value of serum lactate dehydrogenase isoenzyme and amino acid patterns in several schistosomal and non-schistosomal disorders as compared to other biochemical parameters

Serum lactate dehydrogenase (LDH) isoenzyme and amino acid (a.a) patterns were evaluated in comparison to several other biochemical parameters for liver and renal function with the objective of clarifying the differential diagnosis of hepatic disorders and predicting the outcome of schistosomal infection in Egyptian patients. Patients examined included those with complicated hepatic disorders and others with different stages of schistosomal infestation, hepatoma or bladder cancer, in addition to a normal control group. Several biochemical parameters appeared to be useful in establishing consistent differences or similarities between the studied groups. Examples are; elevated serum AST/ALT ratio and methionine content in chronic schistosomiasis, elevated serum urea/creatinine ratio and leucine content in all schistosomal patients and extremely high levels of N-acetyl-beta-D-glucosaminidase (NAG) in the urine of non-schistosomal bladder cancer patients. In addition, characteristic LDH isoenzyme profiles distinguish between the studied groups, in particular separating chronic schistosomiasis from schistosomal bladder cancer and hepatoma from other hepatic disorders.

PCR mutagenesis and overexpression of tryptophan synthase from Salmonella typhimurium: on the roles of beta2 subunit Lys-382

We have devised convenient methods for mutagenesis and very high level expression of wild type and mutant tryptophan synthase alpha and beta2 subunits and alpha2beta2 complex from Salmonella typhimurium. The trpBA genes were modified by introduction of five new restriction sites by polymerase chain reaction (PCR) and were then cloned into the plasmid pTrc99A under trc promoter control. The recombinant plasmid pEBA-10 and three plasmids constructed from pEBA-10 were transformed into Escherichia coli CB149, which lacks tryptophan operon genes. Optimization of growth conditions of the transformed cells resulted in 10- to 40-fold higher yields of cells ( approximately 22 g/liter) than attained previously. The improved expression system gave higher yields of tryptophan synthase proteins (23-70% of the soluble protein) and led to correspondingly high yields of purified alpha and beta2 subunits or alpha2beta2 complex (200-800 mg/liter). A plasmid containing 8 copies of the trpA gene gave the highest yield of alpha subunit. The PCR-based mutagenesis method permits mutation of any base pair in the trpBA genes, between suitable pairs of restriction sites, and requires only one new primer per mutation. The method is illustrated by construction of mutant beta2 subunits with any of five amino acid substitutions at Lys-382, the site of a previously described missense mutation. Characterization of the purified mutant alpha2beta2 complexes shows that Lys-382 in the wild type alpha2beta2 complex does not serve an essential catalytic role but may stabilize an active "closed" conformation of the enzyme by forming a salt bridge with Glu-350.

In vitro cytotoxic activity of equine lymphocytes on equine herpesvirus-1 infected allogenic fibroblasts

The objectives of this study were to: (1) develop a technique to analyze the in vitro cytotoxic activity of lymphocytes from adult horses against equine herpesvirus-1 (EHV-1) infected allogenic equine dermal fibroblasts (EDF); (2) evaluate the ability of a 72-h in vitro incubation with interleukin-2 (IL-2) to enhance the lymphocytic cytolytic activity against EHV-1 infected EDF; (3) compare the cytotoxic activity of lymphocytes isolated from pregnant mares and non-pregnant mares against EHV-1 infected EDF; (4) ascertain if any correlations existed between the percent cytotoxicity and percentage of lymphocytes phenotypically identified by five different mouse-anti-equine monoclonal antibodies; and (5) determine if any correlation existed between virus-neutralizing antibody titers and the percent cytotoxicity. Results of the study indicate that in vitro cytotoxic activity of equine lymphocytes against EHV-1 infected allogenic fibroblasts can be measured with a standard 4-h 51Cr release assay. This activity was enhanced by an in vitro incubation with IL-2. The cytolytic activity of freshly isolated lymphocytes was greater for non-pregnant than pregnant mares. However, after IL-2 stimulation the cytolytic activity was greater for lymphocytes from pregnant mares. A positive correlation was not detected between the percentage of phenotypically identified cells and the percent cytotoxicity, although several negative correlations were present. This suggests that the cytotoxic activity was either not mediated by any of the phenotypically identified cell populations or that the activity was

A thermally induced reversible conformational transition of the tryptophan synthase beta2 subunit probed by the spectroscopic properties of pyridoxal phosphate and by enzymatic activity

A reversible thermally induced conformational transition of the beta2 subunit of tryptophan synthase from Salmonella typhimurium has been detected by use of the pyridoxal 5'-phosphate coenzyme as a spectroscopic probe. Increasing the temperature converts the major form of pyridoxal 5'-phosphate bound to the beta2 subunit from a ketoenamine species with lambdamax at 410 nm to a enolimine species with lambdamax at 336 nm (Tm = approximately 43 degrees C) and results in loss of the circular dichroism signal at 410 nm and of fluorescence emission at 510 nm. The results indicate that increasing the temperature favors a conformer of the enzyme that binds pyridoxal 5'-phosphate in a more nonpolar environment and leads to loss of asymmetric pyridoxal 5'-phosphate binding. The internal aldimine between pyridoxal 5'-phosphate and the epsilon-amino group of lysine 87 is not disrupted by increased temperature because sodium borohydride treatment of the enzyme at either 15 or 60 degrees C results in covalent attachment of [4'-3H]pyridoxal 5'-phosphate. The thermal transition of the beta2 subunit below 60 degrees C produces reversible thermal inactivation (Ti = approximately 52 degrees C) and occurs at a much lower temperature than the major reversible unfolding at approximately 80 degrees C (Remeta, D. P., Miles, E. W., and Ginsburg, A. (1995) Pure Appl. Chem. 67, 1859-1866). Our new results indicate that the 410 nm absorbing species of pyridoxal 5'-phosphate is the catalytically active form of the cofactor in the beta2 subunit and that the low temperature reversible conformational transition disturbs the active site and causes loss of catalytic activity.

Exchange of K+ or Cs+ for Na+ induces local and long-range changes in the three-dimensional structure of the tryptophan synthase alpha2beta2 complex

Monovalent cations activate the pyridoxal phosphate-dependent reactions of tryptophan synthase and affect intersubunit communication in the alpha2beta2 complex. We report refined crystal structures of the tryptophan synthase alpha2beta2 complex from Salmonella typhimurium in the presence of K+ at 2.0 angstrom and of Cs+ at 2.3 angstrom. Comparison of these structures with the recently refined structure in the presence of Na+ shows that each monovalent cation binds at approximately the same position about 8 angstrom from the phosphate of pyridoxal phosphate. Na+ and K+ are coordinated to the carbonyl oxygens of beta Phe-306, beta Ser-308, and beta Gly-232 and to two or one water molecule, respectively. Cs+ is coordinated to the carbonyl oxygens of beta Phe-306, beta Ser-308, beta Gly-232, beta Val-231, beta Gly-268 and beta Leu-304. A second binding site for Cs+ is located in the beta/beta interface on the 2-fold axis with four carbonyl oxygens in the coordination sphere. In addition to local changes in structure close to the cation binding site, a number of long-range changes are observed. The K+ and Cs+ structures differ from the Na+ structure with respect to the positions of beta Asp-305, beta Lys-167, and alpha Asp-56. One unexpected result of this investigation is the movement of the side chains of beta Phe-280 and beta Tyr-279 from a position partially blocking the tunnel in the Na+ structure to a position lining the surface of the tunnel in the K+ and Cs+ structures. The results provide a structural basis for understanding the effects of cations on activity and intersubunit communication.

Effect of growth hormone administration on serum somatomedin-C levels in bilharzial and liver disorders patients

This work was designed in an attempt to clarify the effect of growth hormone injection on the serum somatomedin-C (SM-C) levels in Egyptian children with (1) urinary bilharziasis, (2) advanced bilharzial hepatic fibrosis, and (3) children suffering from chronic hepatitis, in comparing with 11 healthy age- and sex-matched children,, served as controls. SM-C levels were studied prior and after injection of human growth hormone (hGH). The basal and hGH-stimulated SM-C levels were significantly reduced in bilharzial patients compared with controls. Patients with hepatitis had significantly lower serum SM-C values prior or post hGH administration. Liver tests carried out for bilharzial patients showed impaired function both on admission and after treatment. It can concluded from this work that shortness in children with bilharzial hepatic fibrosis may be result of hepatic and endocrinal factors and nutritional. Also, our results suggested that the delayed skeletal maturation in chronic hepatitis cases is probably secondary to liver dysfunction, malnutrition and associated endocrinopathies.

Effect of schistosomal infection and its treatment on some key enzymes of glucose metabolism in mice livers

Three antischistosomal drugs, praziquantel (CAS 55268-74-1, EMBAY 8440, Prz), oxamniquine (CAS 21738-42-1, Oxa) and oltipraz (CAS 64224-21-1, Olt) were examined for their ability to reverse the disturbances in carbohydrate metabolism induced by Schistosoma mansoni (S. mansoni) infection. The infected mice were screened every 2 weeks for 16 weeks for their body and liver weights in addition to assessment of the activities of liver pyruvate kinase (PK), phosphofructokinase (PFK) (glycolysis), citrate synthase (CS) (Krebs' cycle) glycogen phosphorylase (GP) (glycogenolysis), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) (hexose monophosphate shunt). Results of the study showed that infection with S. mansoni caused the following changes in mice livers: 1. significant increase in liver weights from the 6th week of infection, which coincided with schistosomal egg deposition, whereas body weights were reduced, 2. remarkable increase in the activities of PK and PFK from the 4th week of infection, 3. marked reduction in CS, GP, G6PDH and 6PGDH. These results lead to the conclusion that glycolysis is largely stimulated in the livers of infected mice on the expense of other metabolic pathways of glucose utilization. Administration of Prz to infected mice caused normalization of all measured enzyme activities almost from the 2nd week of infection, whereas liver and body weights were improved from the 10th week. Oxa was less effective in these regards while Olt was the least. These data support the selection of Prz as a drug of choice for S. mansoni infection.

A preliminary report on the prognostic value of selected diagnostic enzymes among certain malignant and schistosomal malignant patients

The study is a trial to test certain biochemical parameters as differential diagnostic markers between some pathological malignant cases. The first part of the present article was carried out in order to investigate the effect of both cancerous infestation and schistosomal infection on Lactate dehydrogenase (LDH), two transaminases (ALT and AST) activities and total proteins in both serum and tumor tissue isolated from bladder carcinoma patients. The activities were measured in neighboring mucosa to carcinoma tissues together with bladded tissues excised because of malignant lesions and malignant tissues excised because of urinary schistosomiasis, in Egyptian human patients. The second part was design in order to estimate the effect of cancerous disorders on the previous parameters in serum and isolated tumors among colonic carcinoma patients. In addition, the study was extended to explore the changes that might occurred in serum LDH isoenzymatic pattern among some selected cases from these patients.

Acarboxy prothrombin (PIVKA II) as a tumour marker for hepatocellular carcinoma and other liver diseases

The clinical usefulness of plasma abnormal prothrombin, defined as protein induced by vitamin K absence or antagonist II: (PIVKA II) as a tumour marker for hepatocellular carcinoma (HCC) and other liver diseases has been evaluated. PIVKA II concentrations were determined using an enzyme-linked immunosorbent assay (ELISA) with monoclonal antibody that reacts with PIVKA II but does not cross-react with normal prothrombin. Seventy four patients (74%) out of 100 with HCC had abnormal PIVKA II levels above 0.5 AU/ml (median = 3.4 AU/ml). The level was above 1.0 AU/ml in 66 (66%) of the patients. In contrast the level of PIVKA II was low in patients with bilharzial periportal fibrosis (median = 0.09 AU/ml), patients with liver cirrhosis (median = 0.13 AU/ml), patients with hepatitis (median = 0.025 AU/ml), and essentially undetectable in all the 34 controls. The diagnostic ability of serum alphafoetoprotein (AFP) was also evaluated in these patients. AFP alone can diagnose 51% of the HCC cases. Of the remaining patients with low or negative AFP levels (65%) can be diagnosed using PIVKA II. Abnormal prothrombin is a potential marker for the laboratory diagnosis of hepatocellular carcinoma.

Monovalent cations partially repair a conformational defect in a mutant tryptophan synthase alpha 2 beta 2 complex (beta-E109A)

We are using the tryptophan synthase alpha 2 beta 2 complex as a model system to investigate how ligands, protein-protein interaction, and mutations regulate enzyme activity, reaction specificity, and substrate specificity. The rate of conversion of L-serine and indole to L-tryptophan by the beta 2 subunit alone is quite low, but is activated by certain monovalent cations or by association with alpha subunit to form an alpha 2 beta 2 complex. Since monovalent cations and alpha subunit appear to stabilize an active conformation of the beta 2 subunit, we have investigated the effects of monovalent cations on the activities and spectroscopic properties of a mutant form of alpha 2 beta 2 complex having beta 2 subunit glutamic acid 109 replaced by alanine (E109A). The E109A alpha 2 beta 2 complex is inactive in reactions with L-serine but active in reactions with beta-chloro-L-alanine. Parallel experiments show effects of monovalent cations on the properties of wild type beta 2 subunit and alpha 2 beta 2 complex. We find that CsCl stimulates the activity of the E109A alpha 2 beta 2 complex and of wild type beta 2 subunit with L-serine and indole and alters the equilibrium distribution of L-serine reaction intermediates. The results indicate that CsCl partially repairs the deleterious effects of the E109A mutation on the activity of the alpha 2 beta 2 complex by stabilizing a conformation with catalytic properties more similar to those of the wild type alpha 2 beta 2 complex. This conclusion is consistent with observations that monovalent cations alter the catalytic and spectroscopic properties of several pyridoxal phosphate-dependent enzymes by stabilizing alternative conformations.

Subunit assembly in the tryptophan synthase alpha 2 beta 2 complex. Stabilization by pyridoxal phosphate aldimine intermediates

This work is aimed at understanding subunit assembly in the tryptophan synthase alpha 2 beta 2 complex and the importance of the internal aldimine between pyridoxal phosphate and lysine 87 of the beta 2 subunit of tryptophan synthase for subunit association. We utilize a mutant form of the beta 2 subunit that is unable to form the internal aldimine because lysine 87 is replaced by threonine (K87T). The K87T alpha 2 beta 2 complex is inactive in reactions catalyzed by the beta 2 subunit but retains activity in the reaction catalyzed by the alpha subunit. We find that dialysis removes pyridoxal phosphate much more rapidly from the K87T beta 2 subunit and alpha 2 beta 2 complex than from the wild type counterparts. Activity measurements, gel filtration, and subunit interchange experiments show that the alpha subunit dissociates more readily from the K87T beta 2 subunit than from the wild type beta 2 subunit. The reaction of L-serine to form an external aldimine with pyridoxal phosphate at the active site of the K87T beta 2 subunit markedly increases the affinity for the alpha subunit and slows removal of pyridoxal phosphate by dialysis. We propose that the external aldimine between L-serine and pyridoxal phosphate bridges the N-domain and the C-domain in the K87T beta 2 subunit. This interdomain bridge may mimic the internal aldimine bond in the wild type beta 2 subunit and stabilize pyridoxal phosphate binding. The interdomain bridges formed by the internal aldimine with the wild type beta 2 subunit and by the external aldimine with L-serine in the K87T beta 2 subunit may further stabilize interaction with the alpha subunit because the alpha/beta interaction site contains residues from both N- and C-domains of the beta 2 subunit.

Comparative study on the levels of alpha-fetoprotein (AFP) in different pathological cases

The research represents a trial to demonstrate the changes which probably took place in AFP levels as a tumor marker among pregnant egyptian women suffering from bilharzial and cancerous infestations. It was found that combination of schistosomal infection with pregnancy leads to obvious high significant increase in AFP in late pregnancy (6-8 months) compared to unpregnant patients. Although the combination between bilharzial infestation and early pregnancy leads to increase in AFP level, the differences were non significant compared to unpregnant ones. There is an extremely significant increase in AFP levels among urinary and intestinal schistosomal pregnant patients compared with healthy pregnant women which was higher in intestinal infection and more pronounced in early pregnancy than late ones. Malignancy in combination with pregnancy caused markable greatly significant increase compared to unpregnant patients, and the increases were slightly higher in bladder than colonic cancerous cases and their AFP levels were gradually increased with progress of both pregnancy and malignancy. In combination of malignancy with pregnant schistosomal infested women to study the effect of schistosomal infection the detected increase in AFP was statistically non significant at early pregnancy and malignancy, turned to significancy at late ones either in bladder or colonic cases.

Ligand-mediated changes in the tryptophan synthase indole tunnel probed by nile red fluorescence with wild type, mutant, and chemically modified enzymes

The bacterial tryptophan synthase alpha 2 beta 2 complex contains an unusual structural feature: an intramolecular tunnel that channels indole from the active site of the alpha subunit to the active site of the beta subunit 25 A away. Here we investigate the role of the tunnel in communication between the alpha and beta subunits using the polarity-sensitive fluorescent probe, Nile Red. Interaction of Nile Red in the nonpolar tunnel near beta subunit residues Cys-170 and Phe-280 is supported by studies with enzymes altered at these positions. Restricting the tunnel by enlarging Cys-170 by chemical modification or mutagenesis decreases the fluorescence of Nile Red by 30-70%. Removal of a partial restriction in the tunnel by replacing Phe-280 by Cys or Ser increases the fluorescence of Nile Red more than 2-fold. A binding site for Nile Red in this region near the pyridoxal phosphate coenzyme of the beta subunit is further supported by iodide quenching and fluorescence energy transfer experiments and by molecular modeling based on the three-dimensional structure of the alpha 2 beta 2 complex. Finally, studies using Nile Red as a sensitive probe of conformational changes in the tunnel reveal that allosteric ligands (alpha subunit) or active site ligands (beta subunit) decrease the fluorescence of Nile Red. We speculate that allosteric and active site ligands induce a tunnel restriction near Phe-280 that serves as a gate to control passage of indole through the tunnel.

17 beta-estradiol, but not 5 alpha-dihydrotestosterone, augments antibodies to double-stranded deoxyribonucleic acid in nonautoimmune C57BL/6J mice

The influence of sex hormones on the immune response to foreign antigens as well as self-antigens is now recognized. In this study, we investigated the influence of gender and sex hormones on the development of antibodies to double-stranded DNA in nonautoimmune C57BL/6J mice. Immunoglobulin G (IgG) anti-dsDNA antibodies are commonly present in lupus patients and several autoimmune disease-prone murine strains. We found that C57BL/6J mice have detectable antibodies (IgM and IgG, but not IgA) to dsDNA. Interestingly, the incidence and level of IgG anti-dsDNA antibodies were lower in male than in female mice. Orchidectomy or administration of 5 alpha-dihydrotestosterone to orchidectomized male mice had minimal effects on these antibodies. In contrast, administration of 17 beta-estradiol to orchidectomized or intact males significantly increased both the incidence and levels of anti-dsDNA antibodies. In female mice, ovariectomy decreased whereas administration of estrogen augmented the incidence and levels of anti-dsDNA antibodies in ovariectomized as well as intact female mice. Kinetic studies revealed that estrogen treatment of male and female mice induced earlier and sustained expression of IgG anti-dsDNA antibodies compared to controls. IgG subisotype analysis showed IgG2b to be predominant. In summary, our findings suggest that estrogen, but not dihydrotestosterone, promotes anti-dsDNA antibodies in normal mice.