Risk factors and seroprevalence of hepatitis E evaluated in frozen-serum samples (2002-2003) of pregnant women compared with female blood donors in a Southern region of Brazil.

Hepatitis E has always been related to morbidity in pregnant women. Its epidemiology is not well understood in Brazil. Therefore, we tested sera from 209 pregnant women and 199 female blood donors, collected at a single center in Curitiba, Brazil. The Wantai assay was used for testing the anti-hepatitis E virus (anti-HEV), immunoglobulin G (IgG), and an in-house polymerase chain reaction process for testing HEV RNA. Anti-HEV was detected in 22.5% of the total group, 19% in the pregnant women group, and 26% in the blood donor group (P = 0.11), a much higher prevalence when compared with other studies in Brazil. Demographical analysis showed that 92.4% were born in the South Region of Brazil, 4.9% in the Southeast, and 2.7% were distributed over other regions of the country. With respect to their origin, 99% were from the South, 0.7% from the Southeast, and 0.2% from the Central-West regions. Income, education, race, number of pregnancies, and abortion did differ significantly when comparing both the groups (P < 0.001). Age >30 (P = 0.012) and the number (>3) of pregnancies (P = 0.008) were related to anti-HEV positivity. All anti-HEV IgG-positive females were HEV RNA negative. In conclusion, HEV positivity was found in one out of five young women, which showed an urgent need for further epidemiological studies in Brazil.

High Prevalence of Hepatitis C Virus Infection in Chronic Hemodialysis Patients.

Hepatitis C virus (HCV) infection is very common among hemodialysis (HD) patients. Transmission of infection in this setting has been related to the number of blood transfusions, the duration of hemodialysis and to nosocomial transmission of virus in the dialysis unit. We conducted a study of 74 HD patients to determine the frequency of HCV at a single point in time (cross-sectional analysis), and to evaluate the association between HCV infection and patients' demographic, clinical and biochemical features. Serum samples were tested for anti-HCV antibodies using a third-generation enzyme-linked immunosorbent assay (ELISA). In the case of a positive result, third-generation recombinant immunoblot and HCV RNA detection by polymerase chain reaction (PCR) tests were performed. Collected data included the patient's age, gender, time on HD, number of blood transfusions and serum alanine aminotransferase (ALT) activity. Twenty-nine patients (29/74.4%) were found to be HCV positive using a third-generation ELISA assay. Of these 29 patients, 27 were also positive by recombinant immunoblot assay and 2 patients had indeterminate results. In the anti-HCV ELISA-positive subgroup, 20 (69%) of the 29 patients had detectable HCV RNA. The HCV RNA-positive patients had received more blood transfusions (15&plusm;3 vs. 5&plusm;1 units of packed red blood cells, p<0.0001) and had been on HD for a longer period of time than the HCV RNA-negative patients (65&plusm;32 vs. 32&plusm;29 months, p<0.0001). Mean serum ALT levels were significantly higher in the HCV RNA positive group (30&plusm;18 vs. 15&plusm;9, p<0.0001). We were unable to determine the most likely mode of transmission in our unit, but these results emphasize the need for strict adherence to blood collecting and handling precautions, careful attention to hygiene in the dialysis units, and sterilization of dialysis machines in order to properly combat this frequent infection.

Temperature control for kinetic refolding of heat-denatured ovalbumin.

The folding of heat-denatured ovalbumin, a non-inhibitory serpin with a molecular size of 45 kDa, was examined. Ovalbumin was heat-denatured at 80 degrees C under nonreducing conditions at pH 7.5 and then cooled either slowly or rapidly. Slow cooling allowed the heat-denatured ovalbumin to refold to its native structure with subsequent resistance to digestion by trypsin. Upon rapid cooling, by contrast, the heat-denatured molecules assumed the metastable non-native conformations that were susceptible to trypsin. The non-native species were marginally stable for several days at a low temperature, but the molecules were transformed slowly into the native conformation. Considering data from size-exclusion chromatography and from analyses of CD, intrinsic tryptophan fluorescence, and adsorption of the dye 1-anilinonaphthalene-8-sulfonate, we postulated that the non-native species that accumulated upon rapid cooling were compact but structureless globules with disordered side chains collectively as a folding intermediate. Temperature-jumped CD experiments revealed biphasic kinetics for the refolding process of heat-denatured ovalbumin, with the features of increasing and subsequently decreasing amplitude of the rapid and the slow phases, respectively, with the decrease in folding temperature. The temperature dependence of the refolding kinetics indicated that the yield of renaturation was maximal at about 55 degrees C. These findings suggested the kinetic partitioning of heat-denatured ovalbumin between alternative fates, slow renaturation to the native state and rapid collapse to the metastable intermediate state. Analysis of disulfide pairing revealed the formation of a scrambled form with non-native disulfide interactions in both the heat-denatured state and the intermediate state that accumulated upon rapid cooling, suggesting that non-native disulfide pairing is responsible for the kinetic barriers that retard the correct folding of ovalbumin.

[Intrathecal immunoglobulin synthesis evaluation in bone marrow transplantation]. / Avaliação da síntese intratecal de immunoglobulinas no transplante de medula óssea.

The central nervous system involvement in chronic graft versus host disease (GVHD) has been suggested. Chronic GVHD resembles auto immune connective tissue disorders. In order to investigate the immunoglobulin intra blood brain barrier (BBB) synthesis during chronic GVHD, and contribute to understanding the pathophysiology of the disease, we studied 33 patients who underwent allogeneic bone marrow transplants (BMT) from HLA identical related donors. Immunoglobulin intra BBB synthesis was investigated quantitative and qualitatively. The samples were collected pre BMT, pos BMT and during chronic GVHD. There were no evidence of immunoglobulin intra BBB synthesis, and no oligoclonal bands were found. Only isolated cases suggested IgO and IgA intra BBB synthesis, and in one case IgM during GVHD.

[Blood-brain barrier evaluation in bone marrow transplantation]. / Avaliação da barreira hemato-encepfálica no transplante de medula óssea.

The blood-brain barrier (BBB) contributes to the central nervous system (CNS) immunological isolation. BBB has never been studied in patients who developed chronic graft-versus-host disease (GVHD) after allogeneic bone marrow transplants (BMT), from HLA identical related donors. BBB disruption was investigated through the cerebrospinal fluid (CSF) proteins, quantitative and graphically, in order to detect the incidence and possible pathophysiology of the CNS involvement in chronic GVHD. Thirty three CSF and matched serum samples from chronic myeloid leukemia patients were collected pre BMT pos BMT and during chronic GVHD. There was no evidence of BBB disruption in any patient studied.

Dose-response effect of in vivo administration of endotoxin on polymorphonuclear leukocytes oxidative burst.

In vitro, endotoxin primes polymorphonuclear leukocytes (PMNs) to respond with a greater oxidative burst. The purpose of the present study was to investigate the in vivo effect of a wide range of single endotoxin bolus doses using a rat model. PMNs were subsequently challenged in vitro with phorbol ester to produce reactive oxygen intermediates (ROI). Flow cytometric determination of ROI production by large doses induced a decrease in ROI production by the few PMNs that remained in the circulation. By 6 h after injection, ROI production had returned to basal levels after a high dose, and was still increasing after a low dose. Neutropenia occurred immediately after endotoxin injection. After 6 h, PMN counts returned to almost normal levels with a high dose, but rebound neutrophilia occurred with a small dose. In contrast to in vitro studies, in vivo injection showed a response pattern that varied widely with dose and time of observation.

Toxicity evaluation of the mycotoxins, citrinin and ochratoxin A, using several animal cell lines.

1. The cytotoxicities of the nephrotoxic mycotoxins, citrinin and ochratoxin A were assayed on HeLa, C3H/10T1/2, NIH/3T3, MDCK (canine kidney), and HeLa P3 cell lines, using the MTT colorimetric assay. 2. Citrinin was less toxic than ochratoxin A in all of the cell lines examined. 3. The MDCK cells were more susceptible to both citrinin and ochratoxin A, in comparison with other cell lines. 4. Dose-responses, as measured by activities of leucine aminopeptidase and alkaline phosphatase of MDCK cells, were less sensitive than MTT colorimetric assay, indicating that these enzymes were not specifically inhibited in MDCK cells. 5. The LD50 of both toxins, calculated at 72 hr incubation, was in the same order as those reported from animal experiments using rats and mice.

Dynamic light scattering of aqueous solutions of linear aggregates induced by thermal denaturation of ovalbumin.

Dynamic light scattering measurements were performed on dilute aqueous solutions of native ovalbumin (OA) and on those of linear OA aggregates induced by thermal denaturation at low ionic strength and neutral pH. The weight-average molecular weight MW of four aggregates tested ranged from 1,700,000 to 5,500,000. The translational diffusion coefficient D0 of native OA at infinite dilution was estimated as 8.70 x 10(-7) cm2/s, which gave 56.0 A as the diameter of the rigid spherical particle. The intensity autocorrelation function of linear OA polymers was analyzed with the cumulant method to obtain the first cumulant gamma e. The dependence of gamma e on the scattering vector q at very low polymer concentration was found intermediate between those of a flexible chain and a rigid rod. The translational diffusion coefficient Dtr [identical to (gamma e/q2)q-->0] was in proportion to M-0.55W, and the magnitude was in good agreement with a value calculated from the wormlike cylinder model with values of three parameters determined in an earlier study, ML = 1600 A-1, d = 120 A, and Q = 230 A, where ML, d, and Q are the molecular weight per unit length, diameter, and persistence length, respectively. Based on these results, a new model, to be called as the dimer model, was proposed to interpret the formation mechanism of linear OA polymers induced by thermal denaturation.

Heat-induced Transparent Gel from Hen Egg Lysozyme by a Two-step Heating Method.

The effects of ionic strength and dithiothreitol concentration, a reducing agent, on the heat-induced gelation of a lysozyme solution were examined at pH 7. Two different heating methods were used, one involving single heating, and the other, a two-step heating process in which a sample solution was heated twice under different medium conditions. With 7.5 mM dithiothreitol, a 5% lysozyme solution gave a transparent sol, a transparent gel, a translucent gel and a turbid gel after a single heating with 0, 40, 50, and 60mM NaCI, respectively. When the transparent sol obtained without NaCI was reheated with 50mM NaCI, it produced a firm and transparent gel. This gel was at least 6 times harder than the transparent lysozyme gel obtained by the one-step heating method. High-resolution scanning electron microscopy showed that the transparent gel produced by the two-step heating method had a fine network of linear polymers composed of heat-denatured lysozyme molecules.

Heat-induced Transparent Gel Formation of Bovine Serum Albumin.

The formation of transparent gels by 6% bovine serum albumin (BSA), pH 7.5, was examined by one- and two-step heating methods. Heating of the BSA solutions at various NaCl concentrations produced transparent gels at 25-50mM NaCl and transparent sols at 0-20 mM NaCl (one-step heating method). The transparent sol obtained by heating without NaCl was reheated after mixing with various amounts of NaCl (two-step heating method I). The result was almost identical to that obtained by the one-step heating method. However, when the first heating was done with 10 mM NaCl, transparent gels were obtained over a wide range of NaCl concentrations with a second heating (two-step heating method II). Analyses of sols obtained at various NaCl concentrations by gel permeation chromatography and transmission electron microscopy showed the presence of linear polymers in the heated BSA sol (10 mM NaCl) and gel networks formed by the linear polymers (20 mM NaCl). The mechanism of transparent gel formation in BSA may be similar to that in ovalbumin.

Detoxification of Ochratoxin A on Heating under Acidic and Alkaline Conditions.

Ochratoxin A was heated under three different moisture conditions, and under acidic and alkaline conditions. Heating to 175°C under the dry conditions produced little change in the molecule and cytotoxicity, detected by TLC and in the effects on the proliferation of HeLa cells. When heated under the moist and watery conditions, a small change in molecule was found by TLC, but cytotoxicity was not reduced. Under the acidic conditions (0.1 N HCl) the decomposition of ochratoxin A was detected by TLC, however the change in cytotoxicity was not observed in this assay system. On the other hand, heating with NaOH (0.1 N) resulted in the decomposition and detoxification of ochratoxin A. The HPTLC analysis showed the formation of some decomposed compounds including L-phenylalanine. This indicates the hydrolysis of ochratoxin A is one of the decomposition reactions induced by alkali at high temperatures.

Cytotoxicity of Citrinin Heated at Temperatures above 100°C.

The toxicity of citrinin heated at various temperatures was examined with HeLa cell and judged from the cell proliferation. Citrinin or heated citrinin (0.1, 1.0 or 2.5µg) was added to 3 x 10(3) cells/100µl of medium, and the cell proliferation was monitored for 72 hr. Lethal toxicity was clearly indicated by the addition of 2.5µg of citrinin, while the addition of 0.1 or 1.0µg of citrinin only slightly repressed the cell proliferation. Heating above 160°C was required to detoxify under dry conditions, whereas heating at 100°C reduced toxicity to some extent under aqueous conditions. Consequently, the lower the moisture, the higher was the temperature needed to detoxify citrinin. However, under the aqueous conditions, strong toxicity was observed in the citrinin heated at 140°C, this cytotoxicity becoming weaker by heating at higher or lower temperatures than 140°C and disappearing completely by heating at 170°C.

Role of an intrachain disulfide bond in the conformation and stability of ovalbumin.

Ovalbumin, which contains one intrachain disulfide bond and four cysteine sulfhydryls, was reduced with dithiothreitol under non-denaturing conditions, and its conformation and stability were compared with those of the disulfide-bonded form. The CD spectrum in the far-UV region revealed that the overall conformation of the reduced form is similar to that of the disulfide-bonded one. Likewise, the inaccessibility to trypsin and the non-reactivity of the four cysteine sulfhydryls, exhibited by the native disulfide-bonded ovalbumin, were still retained in the disulfide-reduced form. Thus, the reduced ovalbumin appeared to substantially take the native-like conformation. However, the near-UV CD spectrum slightly differed between the native and disulfide-reduced forms. Protein alkylation with a fluorescent dye and subsequent sequence analysis showed that the two sulfhydryls (Cys73 and Cys120) originating from the disulfide bond are highly reactive in the reduced form. Furthermore, upon proteolysis with subtilisin, the N-terminal side of Cys73 was cleaved in the reduced form, but not in the disulfide-bonded one. Upon heat denaturation, the transition temperature of the reduced form was lower, by 6.8 degrees C, than that of the disulfide-bonded one. Thus, we concluded that ovalbumin has a native-like conformation in its disulfide-reduced form, but that the local conformation of the reduced form fluctuates more than that of the disulfide-bonded one. Such local destabilization may be related to the decreased stability against heat denaturation.

Toxicity of dimethyl sulfoxide as a solvent in bioassay system with HeLa cells evaluated colorimetrically with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide.

The toxicity of dimethyl sulfoxide (Me2SO) was examined in HeLa cells cultured at 37 degrees C for up to 72 hr. The growth of the cells was measured by a colorimetric method with the use of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which gave good correlation between the cell number and the color development from the reduction of MTT under suitable conditions. When the initial number of cells was 3 x 10(4)/ml, Me2SO at 1% or less had no apparent effect on proliferation for up to 48 hr of incubation, but in longer incubations, cell growth was repressed. When the initial number of cells was 3 x 10(5)/ml, the effect of Me2SO was similar.

A long-lasting potentiation of calmodulin-mediated chloride channel activity without a mediation of protein kinase C in Xenopus oocytes injected with rat brain mRNA.

When Xenopus oocytes injected with rat brain poly(A)+RNA were voltage-clamped in a recording solution containing Ca2+, a depolarization pulse induced a transient current, ICl(Ca), which reflects calmodulin-mediated opening of endogenous Cl- channels in response to a Ca2+ influx through Ca2+ channels of brain origin. ICl(Ca) could be repetitively observed with a steady amplitude over 1 h, whereas the response was greatly potentiated for more than 30 min after a brief stimulation of muscarinic or other Ca2(+)-mobilizing receptors. The enhancement of ICl(Ca) was mimicked by an injection of inositol-1,4,5-trisphosphate or by a treatment with A23187, but not affected by treatments that stimulate or inhibit protein kinase C activity. Isolated Ba2+ current flowing through voltage-sensitive Ca2+ channels was not augmented during the facilitation of ICl(Ca). These observations indicate that the endogenous calmodulin/Cl- channel system may memorize an over-threshold increase in the intracellular Ca2+ concentration and potentiate the Ca2(+)-sensitiveness of the Cl- channel. A long-lasting autoregulation of Ca2(+)-dependent ion channel activity is suggested.

Radiological findings of vanishing tumor of the stomach.

Four lesions in three patients with so-called vanishing tumor of the stomach are described. Two patients had one lesion each and the third patient two lesions. The lesions were localized in the gastric cardia, angle, and antrum. Radiological findings of these tumors showed a round tumor with smooth surface and regular margins. The edges of the tumors were gently sloping, while the mucosa surrounding the tumor was edematous. The time interval until these tumors disappeared was five days, 20 months, 12 months and seven months, respectively. When the soft appearance of a gastric tumor is suspected in UGI examination, the patient should be re-examined after a month or more, to avoid unnecessary surgery.

Freezing denaturation of ovalbumin at acid pH.

The effects of rapid freezing and thawing at acid pH on the physiochemical properties of ovalbumin were examined. At low pH (around 2), UV difference spectra showed microenvironmental changes around the aromatic amino acid residues; elution curves by gel permeation chromatography showed decreasing numbers of monomers after neutralization. These changes depended on the incubation temperature (between -196 and -10 degrees C) and the protein concentration (0.5-10 mg/ml), and a low concentration of ovalbumin incubated at around -40 degrees C suffered the most damage to its conformation. With freezing and then incubation at -40 degrees C, three of the four sulfhydryl groups in the ovalbumin molecule reacted with 2,2'-dithiodipyridine. The CD spectra showed these changes in the secondary structure, but they were smaller than those when guanidine hydrochloride was used for denaturation. Supercooling at -15 degrees C or freezing at -196 degrees C had little or no effect on the conformation of the ovalbumin molecule. Thus, irreversible conformational changes of ovalbumin were caused under the critical freezing condition at an acid pH. These changes arose from partial denaturation and resembled those with thermal denaturation of ovalbumin at neutral pH.