Porphyrin–triarylamine conjugates: strong electronic communication between triarylamine redox centers via the porphyrin dication

A set of porphyrin-triarylamine hybrids have been synthesized in good yield by Sonogashira palladium-catalyzed cross-coupling reactions between the zinc complex of 5,15-diethynyl-10,20-dimesitylporphyrin and the appropriate iodophenyldiarylamines. The crystal structure of porphyrin 1 shows that the dihedral angle between the acetylene-bonded benzene rings and the porphyrin macrocycle is 20.0 degrees. Such a structural characteristic enables effective electronic perturbations within the molecule. The electronic spectra are red-shifted and display a broad Soret band and an intense Q band relative to those of meso-substituted tetraarylporphyrins. These conjugates display four oxidations and one reduction. All the electrochemical reactions involve one-electron transfer. The first and second oxidations are reversible and can be assigned to the porphyrin-centered reactions. The third and fourth ones, separated by about 270 mV, correspond to the triarylamine units. The comproportionation constant (Kc) is calculated to be 3.67x10(4). The electron coupling between the triarylamine moieties, at a separation of >23 A, is remarkably strong. The electrochemical results and the absorption spectra show that the electronic characteristics of these porphyrins can be significantly modulated by the triarylamine substituents via the conjugated carbon-carbon triple bond. Variations of the substituents on the triarylamines can fine-tune the electronic properties of these molecules.

Synthesis, structures, magnetism and electrochemical properties of triruthenium–acetylide complexes

A series of triruthenium complexes with arylacetylide axial ligands Ru(3)(dpa)(4)(C(2)X)(2)(BF(4))(y)(dpa = dipyridylamido; X = Fc, y= 0 (1); X = Ph, y= 0 (2); X = PhOCH(3), y= 1 (3); X = PhC(5)H(11), y= 1 (4); X = PhCN, y= 0 (5); X = PhNO(2), y= 0 (6)) have been synthesized. The crystal structures show that the Ru-Ru bond lengths (2.3304(9)-2.3572(5)A) of these compounds are longer than those of Ru(3)(dpa)(4)Cl(2)(Ru-Ru=2.2537(1)A). This is ascribed to the formation of the stronger pi-backbonding from metal to axial ligand which weakens the Ru-Ru interactions and the bond order is reduced in the triruthenium unit. Cyclic voltammetry and differential pulse voltammetry show that compound exhibits electronic coupling between the two ferrocenyl units with DeltaE(1/2) close to 100 mV. Compounds 2-6 display three triruthenium-based reversible one-electron redox couples, two oxidations and one reduction, and the electrode potentials shift upon varying the substituents. A linear relationship is observed when the Hammett constants are plotted against the redox potentials.

Post-operative thrombotic thrombocytopenic purpura: a review

Post-operative thrombotic thrombocytopenic purpura (TTP) is a recently recognised life-threatening clinical syndrome with considerable similarity to classic TTP in presentation and response to early treatment with plasma exchange. To date, 29 cases of TTP associated with surgery have been reported. The majority of cases have complicated vascular surgeries, with a few cases seen following gastrointestinal or orthopaedic procedures. Characteristically, patients develop microangiopathic haemolytic anaemia and consumptive thrombocytopenia 5 to 9 days following surgery with variable presence of fever, impaired renal function and altered mental status. The pathogenesis of post-operative TTP is speculative but may involve the release of large amounts of high-molecular-weight von Willebrand factor (vWF) multimers due to endothelial damage resulting from surgery in the setting of marginal levels of vWF-cleaving enzyme. The myriad of common post-surgical complications that may present with clinical manifestations similar to TTP may result in confusion with the potential for delay in the initiation of life-saving plasma-exchange therapy. It is important that physicians be alert to the phenomenon of post-operative TTP so that prompt recognition and treatment will prevent serious morbidity or mortality.

Quantitation of colonic luminal synthesis of butyric acid in piglets

OBJECTIVES

Butyric acid, synthesized via bacterial fermentation in colonic lumen, may play an important role in the nutrition of the colonic mucosa. Since disaccharides, especially lactose, are the principal dietary carbohydrates during infancy, it is important to determine if their fermentation is associated with butyric acid synthesis. The objective of this paper is to describe a newly developed stable isotope method for quantifying butyric acid synthesis in the colonic lumen and to demonstrate its application during cecal infusions of lactose and lactulose in piglets.

METHODS

Nine piglets aged 21 to 30 days were studied during acute anesthesia. The C enrichment of butyric acid was monitored in the portal vein before and during a 120 minutes cecal infusion of [1- C]-butyric acid and either unlabeled lactose (N = 4) or lactulose (N = 5).

RESULTS

The luminal synthesis of BA (micromol x kg x min ) (Mean +/- S.D.) was respectively 1.5 +/- 0.9 and 1.2 +/- 0.6 during lactulose and lactose infusion.

CONCLUSIONS

This study provides new quantitative data on in vivo butyric acid production in the mammalian colon.

Acculturation and suicide: a case-control psychological autopsy study

BACKGROUND

The relationships between acculturation and suicide were investigated in East Taiwan.

METHODS

Psychological autopsy interviews were conducted for consecutive suicides from two native Taiwanese groups (Atayal and Ami) (N = 30 for each group); each of them was matched with two controls for age, sex and area of residence. The Taiwan Aboriginal Acculturation Scale was used to measure the extent of acculturation.

RESULTS

A lower degree of social assimilation was significantly associated with a higher risk of suicide in the Atayal and the male groups. In multivariable regression analysis, a significant effect of low social assimilation on the risk of suicide was found in Atayal and in men, even after controlling for the effects of ICD-10 depressive episode and emotionally unstable personality disorder. Meanwhile, there was a significant trend across low, moderate and high social assimilation on suicide risk in Atayal and in men.

CONCLUSIONS

For the native Taiwanese, the stress from rapid acculturation into the main Chinese society is crucial to their mental health. It might be reduced through targeted social and educational programmes.

Huntingtin interacting protein 1 Is a clathrin coat binding protein required for differentiation of late spermatogenic progenitors

Huntingtin-interacting protein 1 (HIP1) interacts with huntingtin, the protein whose gene is mutated in Huntington's disease. In addition, a fusion between HIP1 and platelet-derived growth factor beta receptor causes chronic myelomonocytic leukemia. The HIP1 proteins, including HIP1 and HIP1-related (HIP1r), have an N-terminal polyphosphoinositide-interacting epsin N-terminal homology, domain, which is found in proteins involved in clathrin-mediated endocytosis. HIP1 and HIP1r also share a central leucine zipper and an actin binding TALIN homology domain. Here we show that HIP1, like HIP1r, colocalizes with clathrin coat components. We also show that HIP1 physically associates with clathrin and AP-2, the major components of the clathrin coat. To further understand the putative biological role(s) of HIP1, we have generated a targeted deletion of murine HIP1. HIP1(-/-) mice developed into adulthood, did not develop overt neurologic symptoms in the first year of life, and had normal peripheral blood counts. However, HIP1-deficient mice exhibited testicular degeneration with increased apoptosis of postmeiotic spermatids. Postmeiotic spermatids are the only cells of the seminiferous tubules that express HIP1. These findings indicate that HIP1 is required for differentiation, proliferation, and/or survival of spermatogenic progenitors. The association of HIP1 with clathrin coats and the requirement of HIP1 for progenitor survival suggest a role for HIP1 in the regulation of endocytosis.

Rosiglitazone (BRL 49653) enhances insulin secretory response via phosphatidylinositol 3-kinase pathway

To elucidate the direct effect of rosiglitazone (RSG), a new thiazolidinedione antihyperglycemic agent, on pancreatic insulin secretion, an in situ investigation by rat pancreatic perfusion was performed. At a basal glucose concentration of 6 mmol/l, RSG (0.045-4.5 micromol/l) stimulated insulin release in a dose-dependent manner. In addition, 4.5 micromol/l RSG potentiated the glucose (10 mmol/l)-induced insulin secretion. Both the first and second phases of glucose-induced insulin secretion were significantly enhanced by RSG, by 80.7 and 52.4%, respectively. The effects of RSG on insulin secretion were inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. In contrast, the glucose-stimulated insulin secretion was not affected by LY294002. The potentiation effect of RSG on glucose-stimulated insulin secretion, in both the first and second phases, was significantly blocked by LY294002. These results suggest that RSG has a direct potentiation effect on insulin secretion in the presence of 10 mmol/l glucose, mediated through PI3K activity. The inability of LY294002 to inhibit glucose-induced insulin secretion suggests that different pathways are responsible for glucose and RSG signaling.

Identification and characterization of the neutralization epitope(s) of the hepatitis E virus

The neutralization epitope(s) of the hepatitis E virus (HEV) was studied by an in vitro neutralization assay using antibodies obtained by immunization of mice with 51 overlapping 30-mer synthetic peptides spanning the region 221-660 amino acids (aa) of the HEV open reading frame 2 encoded protein (pORF2) and 31 overlapping recombinant proteins of different sizes derived from the entire pORF2 of the HEV Burma strain. Antibodies against synthetic peptides and short recombinant proteins of approximately 100 aa did not neutralize HEV, suggesting the HEV neutralization epitope(s) is conformation-dependent. However, one recombinant protein of approximately 400 aa in length comprising the pORF2 sequence at position 274-660 aa as well as all truncated derivatives of this protein containing region 452-617 aa elicited antibodies, demonstrating HEV neutralizing activity. These findings establish for the first time that the minimal size fragment, designated pB166, that can efficiently model the neutralization epitope(s) is 166 aa in length and is located at position 452-617 aa of the HEV pORF2. Additionally, antibodies against pB166 were found to cross-neutralize three different HEV genotypes, suggesting that a common neutralization epitope(s) may exist within the different HEV genotypes. Thus, recombinant proteins constructed in this study may be considered as potential candidates for the development of an HEV subunit vaccine as well as for the development of highly sensitive and specific diagnostic tests.

Modulation of neural network activity by patterning

Using neuronal cultures on microelectrode arrays, researchers have shown that recordable electrical activity can be influenced by chemicals in the culture environment, thus demonstrating potential applicability to biosensors or drug screening. Since practical success requires the design of robust networks with repeatable, reliable responses understanding the sources of variation is important. In this report, we used lithographic technologies to confine neurons to highly defined patterns (40 microm wide stripes); in turn these patterns gave us a measure of control over the local density of neurons (100-500 cells/mm(2)). We found that the apparent electrical activity of the network, as measured by the fraction of electrodes from which signals were recordable, increases 8-10-fold with greater local density. Also, average-firing rates of the active neurons increased 3-5-fold. We conclude that patterned networks offer one means of controlling and enhancing the responsiveness of cultured neural networks.

Positional importance of Pro53 adjacent to the Arg49-Gly50-Asp51 sequence of rhodostomin in binding to integrin alphaIIbbeta3

Rhodostomin (RHO), a disintegrin isolated from snake venom, has been demonstrated to inhibit platelet aggregation through interaction with integrin alphaIIbbeta3, but there is a lack of direct evidence for RHO-integrin alphaIIbbeta3 binding. In addition, no study on the length of Arg(49)-Gly(50)-Asp(51) (RGD) loop of RHO influencing on its binding to integrin alphaIIbbeta3 has been reported. In the present study we have developed a highly sensitive dot-blot and glutathione S-transferase-RHO pull-down assays; the latter was coupled with a biotin-avidin-horseradish peroxidase enhanced-chemiluminescence detection system. These were able to demonstrate the direct binding of RHO to integrin alphaIIbbeta3. The pull-down assay further showed that four alanine-insertion mutants upstream of the RGD motif and three insertions downstream of the RGD were able to decrease integrin alphaIIbbeta3 binding activity to only a limited extent. By contrast, two insertions immediately next to RGD and one insertion in front of the Cys(57) caused almost complete loss of binding activity to alphaIIbbeta3. The results of the platelet-aggregation-inhibition assay and platelet-adhesion assay for the insertion mutants were consistent with results of the pull-down assay. It is thus concluded that, although an insertion of a single alanine residue in many positions of the RGD loop has only minor effects on RHO binding to integrin alphaIIbbeta3, the specific position of Pro(53) residue adjacent to the RGD sequence is important for RHO binding to platelet integrin alphaIIbbeta3.

Prevalence of C282Y and H63D mutations in the hemochromatosis (HFE) gene in the United States

CONTEXT

Population-based estimates of the prevalence of disease-associated mutations, such as hemochromatosis (HFE) gene mutations, are needed to determine the usefulness of genetic screening.

OBJECTIVE

To estimate the prevalence of the HFE mutations C282Y and H63D in the US population.

DESIGN

Cross-sectional population-based study of samples in the DNA bank from phase 2 of the Third National Health and Nutrition Examination Survey conducted from 1992 to 1994.

SETTING AND PARTICIPANTS

Genotyped samples of cells from a total of 5171 participants, cross-classified by sex, age, and race/ethnicity in the analysis.

MAIN OUTCOME MEASURES

Estimates of the prevalence of C282Y and H63D mutations.

RESULTS

The prevalence of C282Y homozygosity is estimated to be 0.26% (95% confidence interval [CI], 0.12%-0.49%); 1.89% (95% CI, 1.48%-2.43%) for H63D homozygosity; and 1.97% (95% CI, 1.54%-2.49%) for compound heterozygosity. The prevalence estimates for C282Y heterozygosity (C282Y/wild type) are 9.54% among non-Hispanic whites, 2.33% among non-Hispanic blacks, and 2.75% among Mexican-Americans. The prevalence estimates of the C282Y mutation in the US population are 5.4% (95% CI, 4.7%-6.2%) and 13.5% (95% CI, 12.5%-14.8%) for the H63D mutation.

CONCLUSIONS

Estimates of prevalence of HFE mutations are within the expected range for non-Hispanic whites and blacks but the estimated prevalence of the C282Y mutation among Mexican-Americans is less than expected. Mutation data now need to be linked to clinically relevant indices, such as transferrin saturation level.

Acute respiratory distress syndrome as a major clinical manifestation of thrombotic thrombocytopenic purpura

BACKGROUND

Although the classical triad of thrombocytopenia, microangiopathic hemolytic anemia, and neurological changes has been well recognized, thrombotic thrombocytopenic purpura (TTP) sometimes presents with atypical clinical features. Some cases of acute respiratory distress syndrome (ARDS) were suspected to be a manifestation of TTP.

METHODS

We examined retrospectively the medical records of patients with known TTP from 1981 to 1998. The patients who developed ARDS simultaneously with TTP were identified. Clinical, laboratory, and other pertinent data were reviewed; the clinical outcome was documented.

RESULTS

Seven out of 56 patients with an established diagnosis of TTP were identified as having ARDS. All 7 patients had progressive dyspnea, persistent hypoxemia with diffuse pulmonary infiltrates, and no evidence of localized pneumonia, pulmonary emboli, congestive heart failure, or other identifiable lung diseases. In addition to ARDS, 4 patients developed progressive neurological (mental) changes, 3 developed fever, and 2 developed renal failure. Six patients were treated with ventilatory support in the ICU. Upon establishing the diagnosis of TTP, 6 patients were treated with exchange plasmapheresis (EP) and 1 patient with an infusion of fresh frozen plasma. Within 2 days of initiation of EP, 4 patients showed marked respiratory improvement; shortly thereafter, mechanical ventilation was ended. Complete and long-lasting remission was achieved in all 4 patients. Three patients died because of delayed diagnosis and untimely employment of EP.

CONCLUSION

Life-threatening ARDS can be associated with TTP. It is recommended that all patients with ARDS and unexplained thrombocytopenia be evaluated for unrecognized TTP. Early recognition of ARDS associated with TTP and timely EP is critical to a favorable outcome.

Genetic basis for the beta-haemolytic/cytolytic activity of group B Streptococcus

Group B streptococci (GBS) express a beta-haemolysin/cytolysin that contributes to disease pathogenesis. We report an independent discovery and extension of a genetic locus encoding the GBS beta-haemolysin/cytolysin activity. A plasmid library of GBS chromosomal DNA was cloned into Escherichia coli, and a transformant was identified as beta-haemolytic on blood agar. The purified plasmid contained a 4046 bp insert of GBS DNA encoding two complete open reading frames (ORFs). A partial upstream ORF (cylB) and the first complete ORF (cylE) represent the 3' end of a newly reported genetic locus (cyl) required for GBS haemolysin/cytolysin activity. ORF cylE is predicted to encode a 78.3 kDa protein without GenBank homologies. The GBS DNA fragment also includes a previously unreported ORF, cylF, with homology to bacterial aminomethyltransferases, and the 5' end of cylH, with homology to 3-ketoacyl-ACP synthases. Southern analysis demonstrated that the cyl locus was conserved among GBS of all common serotypes. Targeted plasmid integrational mutagenesis was used to disrupt cylB, cylE, cylF and cylH in three wild-type GBS strains representing serotypes Ia, III and V. Targeted integrations in cylB, cylF and cylH retaining wild-type haemolytic activity were identified in all strains. In contrast, targeted integrations in cylE were invariably non-haemolytic and non-cytolytic, a finding confirmed by in frame allelic exchange of the cylE gene. The haemolytic/cytolytic activity of the cylE allelic exchange mutants could be restored by reintroduction of cylE on a plasmid vector. Inducible expression of cylE, cylF and cylEF demonstrated that it is CylE that confers haemolytic activity in E. coli. We conclude that cylE probably represents the structural gene for the GBS haemolysin/cytolysin, a novel bacterial toxin.

Acute thrombotic thrombocytopenic purpura following abdominal surgeries: a report of three cases

Acute thrombotic thrombocytopenic purpura (TTP) occurred in three patients following abdominal surgeries. One patient underwent extensive lysis for intestinal adhesions with bowel resection, another cholecystectomy for acute cholecystitis, and the third right colectomy and partial intestinal resection for colon cancer. The diagnosis of acute TTP was established on the basis of absent hematologic features of TTP prior to surgery and development of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and unexplained mental changes after surgery. Hematologic evidence of TTP developed 3 to 9 days after surgery. Other clinical features were acute respiratory distress syndrome (ARDS) in two patients and peripheral digit ischemic syndrome (PDIS) also in two patients. In all three patients, establishing the diagnosis of TTP was delayed. Exchange plasmapheresis in one patient was ineffective due to associated ARDS and two others died soon after the diagnosis was established. In view of our experience, postoperative TTP should be considered in the differential diagnosis of the patient who develops unexplained anemia and thrombocytopenia following an abdominal surgery. Presence of hemolytic anemia, schistocytosis, and unexplained thrombocytopenia should alert the possibility of TTP.

Laser-induced thermal events in empty and pulp-filled dental pulp chambers

BACKGROUND AND OBJECTIVE

The purpose of this investigation was to evaluate: 1. thermal events during laser irradiation @2.1 microns of the pulp; 2. whether these effects are adequately modeled using an empty pulp chamber/root canal.

STUDY DESIGN/MATERIALS AND METHODS

In extracted human teeth, pulpal access was prepared and thermocouples placed 2, 3 mm apical to the center of the irradiation spot. Pulp-filled or empty pulp chambers were irradiated using a Ho:YAG laser: Spot Size: 1 mm; Power: 1, 2, 3.5, 4.5 W; PRR: 5, 12 Hz;

DURATION

10 sec. Thermal measurements were repeated 3x.

RESULTS

Thermal trends did not differ significantly and correlated positively with power (P < 0.01), PRR (P < 0.01), irradiation duration (P < 0.05). No significant difference was determined between temperatures in empty and pulp-filled chambers at all parameters at 5 Hz and at 1-2 W at 12 Hz (P < 0.05, 2-tailed Student's t-test). At 12 Hz and > 3.5 W, pulp chamber temperatures exceeded those in pulpal tissue (P < 0.05).

CONCLUSION

Pulp tissues must be present to ensure clinical relevance of thermal measurements.

Trends in chronic obstructive pulmonary disease mortality

This study examines the mortality trends for chronic obstructive pulmonary disease (COPD) among whites and African Americans in Missouri from 1980-1996. Data from the Missouri Center for Health Information Management and Epidemiology were used to calculate mortality rates. Missouri's COPD deaths rose 40.6% from 1980-1996. Projections through the year 2006 predict continued escalation in rates. Much of the growth in COPD can be attributed to heavy tobacco use in the population.

Butyric acid is synthesized by piglets

We hypothesized that there is no synthesis of butyric acid within organs or tissues not drained by the portal vein (PV). Two experiments were performed. In six piglets, the colonic vasculature was clamped (n = 4) or the entire colon resected while [1-13C]-butyric acid (99% enriched) was infused into a jejunal vein for 120 min; 13C enrichment of butyric acid was measured in the PV and carotid artery (ART) during the last 30 min of the infusion. In a second experiment, butyric acid tracer and unlabeled disaccharide were infused into the cecum for 120 min, and blood again was sampled from the PV and ART. For the four piglets studied during ligation of the colonic vasculature, the mean (+/- SD) ratio of the butyric acid enrichment in the ART to that in the PV (ART/PV) was 0.80+/-0.05 (ART vs. PV, P = 0.002) and for all six piglets in expt. 1, the ART/PV ratio was 0.74+/-0.1 (ART vs. PV, P = 0.001). The enrichment of butyric acid in the PV averaged 96.0% for the six studies, implying that splanchnic tissues other than the colon did not produce a substantial amount of butyric acid. For the second experiment, the ART/PV ratio was 0.80+/-0.15 (ART vs. PV, P = 0.03). These studies provide the first evidence for endogenous synthesis of butyric acid by piglets.

Wolf-Hirschhorn (4p deletion) syndrome: report of one case

Wolf-Hirschhorn syndrome is an uncommon chromosomal disorder caused by loss of material from the distal aspect of the short arm of chromosome 4. Its characteristic features include profound growth retardation with psychomotor delay, severe mental deficiency, facial dysmorphia, midline defects and skeletal anomalies. We herein report a case of 4p deletion syndrome and review related literature.

Prognostic relevance of cerbB2 expression following neoadjuvant chemotherapy in patients in a randomised trial of neoadjuvant versus adjuvant chemoendocrine therapy

Recent advances in the detection and treatment of breast cancer have led to an intensive search for new markers of both prognosis and chemoresponsiveness. The oncogene cerbB2 has proved to be one of the most promising markers currently under study, both as a predictor of chemoresponsiveness and as a marker of poor prognosis. In addition the increasing use of neoadjuvant chemotherapy has led to the loss of standard prognostic criteria. In order to study the potential role of cerbB2 expression as an indicator of chemoendocrine resistance and poor prognosis, both before and after chemotherapy, we obtained tumour sections from 283 women enrolled onto a neoadjuvant trial. In this trial patients were randomised to receive either primary surgery followed by adjuvant chemoendocrine treatment or neoadjuvant chemoendocrine therapy followed by surgery. CerbB2 status was determined immunohistochemically on all of these patients. Thirty-eight percent of the tumours were cerbB2 positive. There was no significant difference in expression between the adjuvant (41%) and neoadjuvant arms (35%). CerbB2 positive patients were much more likely to have shown non-response to chemoendocrine therapy (p < 0.001) and had a worse DES (p < 0.05). The best prognosis was seen in cerbB2 negative patients receiving neoadjuvant chemoendocrine therapy who showed a significantly better DFS (p < 0.05), than the cerbB2 negative patients receiving adjuvant therapy.

Evaluation of low-VOC latex paints

Four commercially available low-volatile organic compound (VOC) latex paints were evaluated as substitutes for conventional latex paints by assessing both their emission characteristics and their performance as coatings. Bulk analysis indicated that the VOC contents of all four paints tested were considerably lower than those of conventional latex paints. Low VOC emissions were confirmed by small chamber emission tests. However, significant emissions of several aldehydes, especially formaldehyde which is a hazardous air pollutant, were detected in emissions from two of the four paints. American Society for Testing and Materials (ASTM) methods were used to evaluate the hiding power, scrub resistance, washability, dry to touch and yellowness index. The results indicated that one of the four low-VOC paints tested showed performance equivalent or superior to that of a conventional latex paint used as control. It was concluded that low-VOC latex paint can be a viable option to replace conventional latex paints for prevention of indoor air pollution. However, paints marketed as "low-VOC" may still have significant emissions of some individual VOCs, and some may not have performance characteristics matching those of conventional latex paints.

Artificial NS4 mosaic antigen of hepatitis C virus

An artificial antigen composed of 17 small antigenic regions derived from the NS4-protein of hepatitis C virus (HCV) genotypes 1 through 5 was designed and constructed. Eleven antigenic regions were derived from the 5-1-1 region, and 6 others were derived from the C-terminus of the NS4-protein of different genotypes. The gene encoding for this artificial antigen was assembled from synthetic oligonucleotides by a new approach designated as restriction enzyme-assisted ligation (REAL). The full-length synthetic gene was expressed in Escherichia coli as a fusion protein with glutathione S-transferase. By the use of site-specific antibodies raised against synthetic peptides, it was shown that all regions for which sequence-specific antibodies were obtained were accessible to antibody binding. The diagnostic relevance of the NS4 artificial antigen was demonstrated by testing this antigen with 4 HCV seroconversion panels and a panel of previously tested and stored serum specimens. The artificial antigen was found to specifically detect anti-NS4 antibodies in a number of specimens that were previously found to be anti-NS4 negative. Furthermore, this antigen detected anti-NS4 activity earlier in 2 of 4 seroconversion panels than did the antigen used in a commercially available supplemental assay. Equally important is the observation that the artificial NS4 antigen demonstrated equivalent anti-NS4 immunoreactivity with serum specimens obtained from patients infected with different HCV genotypes, whereas the NS4 recombinant protein derived from genotype 1, used in the commercial supplemental test, was less immunoreactive with serum specimens containing HCV genotypes 2, 3, and 4. Collectively, these data support the significant diagnostic potential of the NS4 mosaic antigen. The strategy employed in this study may be applied to the design and construction of other artificial antigens with improved diagnostically pertinent properties. J. Med. Virol. 59:437-450 1999.

K+ binding sites and interactions between permeating K+ ions at the external pore mouth of an inward rectifier K+ channel (Kir2.1)

The arginine at position 148 is highly conserved in the inward rectifier K+ channel family. Increases of external pH decrease the single-channel conductance in mutant R148H of the Kir2.1 channel (arginine is mutated into histidine) but not in the wild type channel. Moreover, in 100 mM external K+, varying external pH induced biphasic changes of open channel noise, which peaks at around pH 7.4 in the R148H mutant but not in the wild type channel. The maximum single-channel conductances are higher in the wild type channel and R148H mutant at pH 6.0 than those in the R148H mutant at pH 7.4. However, the maximal conductance is achieved with much lower external [K+] for the latter. Interestingly, the single-channel conductances and open channel noise of the wild type channel at pH 6. 0 and the R148H mutant at pH 6.0 and 7.4 become the same in [K+] = 10 mM. These results indicate that the residue at position 148 is accessible to the external H+ and probably is involved in the formation of two K+ binding sites in the external pore mouth. Effective repulsion between permeating K+ ions in this area requires a positive charge at position 148, and such K+-K+ interaction is the essential mechanism underlying high K+ conduction rate through the Kir2.1 channel pore.

Antigenic heterogeneity of the hepatitis C virus NS4 protein as modeled with synthetic peptides

The effect of sequence heterogeneity on the immunologic properties of two strong antigenic regions of the hepatitis C virus (HCV) NS4 protein was studied by using a set of 443 overlapping 20-mer synthetic peptides. One antigenic region comprising the cleavage site between NS4a and NS4b (region 5-1-1) was modeled with peptides derived from 73 different known sequences, representing HCV genotypes 1-6. The other antigenic region, designated region 59 and located at the C-terminus of the NS4b protein, was modeled with peptides from 7 known sequences representing genotypes 1-3. All peptides were tested for antigenic reactivity by enzyme immunoassay with a panel of anti-HCV-positive serum specimens representing genotypes 1-5. The data demonstrated that immunoreactive peptides fell into two groups. One group, represented by N-terminal peptides, demonstrated genotype-independent immunoreactivity; the other group, from the central part of region 5-1-1, showed strict genotype specificity. Nineteen peptides from the genotype-independent group strongly immunoreacted with a wide range of serum samples containing antibodies to all 5 HCV genotypes. Twenty-five peptides from the genotype-specific group were found to strongly react with serum containing antibodies only to the genotype from which the peptides were derived. Similar to the N-terminal part of region 5-1-1, peptides derived from region 59 did not show genotype-specific immunoreactivity. Some peptides derived from the central part of region 59 showed very strong and broad antigenic reactivity. Thus, after examining two antigenic regions of the NS4 protein, we identified short sequences that can be used for the efficient detection of either genotype-independent or genotype-specific HCV antibodies.