The free radical-generating function of a familial amyotrophic lateral sclerosis-associated D90A Cu,Zn-superoxide dismutase mutant

The free radical-generating functions of the D90A Cu,Zn-superoxide dismutase (SOD) associated with Swedish familial amyotrophic lateral sclerosis (FALS) patients are investigated. The results show that both the wild-type and mutant enzymes have identical dismutase activity, while the free radical-generating activity of the D90A mutant is enhanced relative to that of the wild-type enzyme. The studies suggest that the active channel of the D90A mutant is larger than that of the wild-type enzyme. A higher free radical-generating activity of the mutant enzyme led to the release of copper ions from the damaged protein. The generation of strand breaks in plasmid DNA was enhanced more effectively by the D90A mutant Cu,Zn-SOD than by the wild-type enzyme. The results suggest that the pathology of FALS may be attributed to oxidative damage caused by the gain-of-function of FALS Cu,Zn-SOD mutant.

Multiple orientation-dependent, synergistically interacting, similar domains in the ribosomal DNA replication origin of the fission yeast, Schizosaccharomyces pombe

Previous investigations have shown that the fission yeast, Schizosaccharomyces pombe, has DNA replication origins (500 to 1500 bp) that are larger than those in the budding yeast, Saccharomyces cerevisiae (100 to 150 bp). Deletion and linker substitution analyses of two fission yeast origins revealed that they contain multiple important regions with AT-rich asymmetric (abundant A residues in one strand and T residues in the complementary strand) sequence motifs. In this work we present the characterization of a third fission yeast replication origin, ars3001, which is relatively small ( approximately 570 bp) and responsible for replication of ribosomal DNA. Like previously studied fission yeast origins, ars3001 contains multiple important regions. The three most important of these regions resemble each other in several ways: each region is essential for origin function and is at least partially orientation dependent, each region contains similar clusters of A+T-rich asymmetric sequences, and the regions can partially substitute for each other. These observations suggest that ars3001 function requires synergistic interactions between domains binding similar proteins. It is likely that this requirement extends to other fission yeast origins, explaining why such origins are larger than those of budding yeast.

The genetics of vitiligo in Korean patients

BACKGROUND

Vitiligo is a common disorder whose exact cause is unknown, but genetic factors are thought to be involved. We analyzed 120 Korean proband families to clarify which genetic factors are involved in the pathogenesis of vitiligo in Korean patients.

METHODS

The genetics of vitiligo were analyzed in 120 Korean proband families out of 1030 vitiligo patients. Each family was analyzed through a proband afflicted with vitiligo.

RESULTS

In 51 (42.5%) of 120 proband families, at least one first-degree relative of the proband had vitiligo. The incidence of those affected among 1755 relatives (first-, second-, and third-degree) was found to be 8.0+/-0.6%. There was a statistically significant departure for segregation analysis which was inconsistent with inheritance as an autosomal or X-linked locus model. On the basis of our results, the inheritance pattern of vitiligo is more likely to tend toward the model of multifactorial inheritance. The threshold trait among first-degree relatives (7.2%) appeared to tend more toward the square root of the frequency in the general population (10%) than towards those of dominant (50%) or recessive (25%) models.

CONCLUSIONS

These results indicate that there are certain genetic factors involved in the etiology of vitiligo, and that vitiligo seems to have a polygenic nature.

Comparison of viscoelastic properties of the pharyngeal tissue: human and canine

The viscoelastic properties of the human and canine pharyngeal tissue in tension were evaluated, based on both an experimental protocol-consisting of cyclic load, tensile stress relaxation, and incremental step load tests-and the quasi-linear viscoelastic theory. The reduced stress relaxation function and the elastic response of the pharyngeal tissues were derived from the experimental results specifically obtained from those tissues. The characteristic features of viscoelastic property were obtained for both human and canine pharyngeal tissues by applying the quasi-linear viscoelastic theory and compared with each other. The material properties of the pharyngeal tissue were sought to facilitate the three-dimensional biomechanical model of the pharyngeal function by using the finite element method.

Vascular leiomyoma of an extremity: MR imaging-pathology correlation

OBJECTIVE

The objective of our study was to analyze MR images of vascular leiomyoma of the extremity and to compare these images with histopathologic findings to determine if a correlation exists.

CONCLUSION

T2-weighted MR images of vascular leiomyoma of an extremity showed a mass with mixed areas that were both hyper- and isointense to skeletal muscle and also revealed a hypointense rim; these images correlate with histopathologic findings of smooth muscle, vessels, fibrous tissue, an intravascular thrombus, and a fibrous capsule.

Comparative assessment of four different Tl-201 tumor uptake indices in the evaluation of brain tumors

The objective of this study was to determine which semi-quantitative thallium-201 brain tumor index correlated best with clinical outcome. Fifty-two patients had Tl-201 brain single-photon emission computer tomography (SPECT) performed for the evaluation of recurrent brain tumor. A semi-quantitative tumor index was calculated utilizing four currently available techniques: 1) the ratio of average counts of the region of interest (ROI) in the lesion area and its mirror image in normal brain tissue, 2) the ratio of maximum counts of the region of interest in the lesion area and its average counts in the mirror image, 3) the ratio of maximum counts of the region of interest in the lesion area and its mirror image and 4) the ratio of the average counts of the region of interest in the lesion area and the region of interest of the scalp. A two-tailed Student's t test was performed. The mean value plus one standard deviation was used to assess the sensitivity and specificity correlated with clinical follow-up evaluation, defined as inactive or active at the time of brain SPECT by the referring neurosurgeons. Results of correlation coefficient, P value, mean, standard deviation, sensitivity, and specificity of each index using cutoff values were obtained. For those patients with recurrence or residual malignant tumor after therapy, the maximum count ratio index correlated best with clinical outcome. It provided a sensitivity of 92% and specificity of 88% in differentiating active from inactive brain tumors.

Effect of superoxide and superoxide-generating systems on the prooxidant effect of iron in oil emulsion and raw turkey homogenates

Mechanisms of superoxide.O2--generating systems on the pro-oxidant effect of iron from various sources were studied. Reaction mixtures were prepared with distilled water, oil emulsion, or meat homogenates. Free ionic iron (ferrous and ferric), ferritin and hemoglobin (Hb) were used as iron sources, and KO2 and xanthine oxidase (XOD) systems were used to produce .O2-. Thiobarbituric acid reactive substances (TBARS) values and iron contents of the reaction mixtures were determined. Ferric iron and ferritin, in the presence or absence of superoxide-generating systems, had no catalytic effect on the oxidation of oil emulsion but became pro-oxidants when reducing agent (ascorbate) was present. Ferrous iron and Hb had strong catalytic effects on the oxidation of oil emulsion as shown by TBARS values. Superoxide and H2O2, generated from superoxide-generating systems, oxidized ferrous iron and ascorbate, and lowered the pro-oxidant effect of ferrous iron in oil emulsion. Addition of ferric or ferrous iron increased but Hb did not have any effect on the TBARS values of raw meat homogenates. The reaction mechanisms of superoxide and the superoxide-generating systems on the prooxidant effect of various iron sources indicated that .O2- was a strong oxidizer rather than a reducing agent, and the antioxidant effect of XOD system in oil was caused by the oxidation of ferrous iron to the ferric form by .O2- and/or H2O2.

Expression, purification, and characterization of a familial amyotrophic lateral sclerosis-associated D90A Cu,Zn-superoxide dismutase mutant

Cu,Zn-superoxide dismutase (SOD) is known to be a locus of mutation in familial amyotrophic lateral sclerosis (FALS). We cloned the FALS mutant, D90A, and wild-type of human Cu,Zn-SOD, overexpressed them in E. coli, purified the proteins, and studied their properties. We investigated their enzymic activities for catalyzing the dismutation of superoxide anions and the generation of free radicals with H2O2 as a substrate. Our results showed that both wild-type and mutant enzymes have identical dismutation activities. However, the hydroxyl radical-generating function of the D90A mutant, as measured using a 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate), was enhanced relative to that of the wild-type enzyme. Catalysis of this reaction by D90A was more sensitive to inhibition by the copper chelators, penicillamine and diethyldithiocarbamate, than was catalysis by wild-type Cu,Zn-SOD. Our study suggests that this gain-of-function of FALS mutant may, in part, be responsible for the development of FALS symptoms.

Identification of toxin A-negative, toxin B-positive Clostridium difficile by PCR

Toxigenic strains of Clostridium difficile have been reported to produce both toxins A and B nearly always, and nontoxigenic strains have been reported to produce neither of these toxins. Recent studies indicate that it is not always true. We established a PCR assay to differentiate toxin A-negative, toxin B-positive (toxin A-, toxin B+) strains from both toxin-positive (toxin A+, toxin B+) strains and both toxin-negative (toxin A-, toxin B-) strains as an alternative to cell culture assay and enzyme-linked immunosorbent assay (ELISA). By using the PCR primer set NK11 and NK9 derived from the repeating sequences of the toxin A gene, a shorter segment (ca. 700 bp) was amplified from toxin A-, toxin B+ strains compared to the size of the segment amplified from toxin A+, toxin B+ strains (ca. 1,200 bp), and no product was amplified from toxin A-, toxin B-strains. We examined a total of 421 C. difficile isolates by PCR. Of these, 48 strains showed a shorter segment by the PCR, were negative by ELISAs for the detection of toxin A, and were positive by cell culture assay. Although the cytotoxin produced by the toxin A-, toxin B+ strains was neutralized by anti-toxin B serum, the appearance of the cytotoxic effects on Vero cell monolayers was distinguishable from that of toxin A+, toxin B+ strains. By immunoblotting, the 44 toxin A-, toxin B+ strains were typed to serogroup F and the remaining four strains were serogroup X. Pulsed-field gel electrophoresis separated the 48 strains into 19 types. The PCR assay for the detection of the repeating sequences combined with PCR amplification of the nonrepeating sequences of either the toxin A or the toxin B gene is indicated to be useful for differentiating toxin A-, toxin B+ strains from toxin A+, toxin B+ and toxin A-, toxin B- strains and will contribute to elucidation of the precise role of toxin A-, toxin B+ strains in intestinal diseases.

Rapid increase of cytosolic content of acetyl-CoA carboxylase isoforms in H9c2 cells by short-term treatment with insulin and okadaic acid

Mammalian acetyl-CoA carboxylase (ACC) is present in two isoforms, alpha and beta, both of which catalyze formation of malonyl-CoA by fixing CO2 into acetyl-CoA. ACC-alpha is highly expressed in lipogenic tissues whereas ACC-beta is a predominant form in heart and skeletal muscle tissues. Even though the tissue-specific expression pattern of two ACC isoforms suggests that each form may have a distinct function, existence of two isoforms catalyzing the identical reaction in a same cell has been a puzzling question. As a first step to answer this question and to identify the possible role of ACC isoforms in myogenic differentiation, we have investigated in the present study whether the expression and the subcellular distribution of ACC isoforms in H9c2 cardiac myocyte change so that malonyl-CoA produced by each form may modulate fatty acid oxidation. We have observed that the expression levels of both ACC forms were correlated to the extent of myogenic differentiation and that they were present not only in cytoplasm but also in other subcellular compartment. Among the various tested compounds, short-term treatment of H9c2 myotubes with insulin or okadaic acid rapidly increased the cytosolic content of both ACC isoforms up to 2 folds without affecting the total cellular ACC content. Taken together, these observations suggest that both ACC isoforms may play a pivotal role in muscle differentiation and that they may translocate between cytoplasm and other subcellular compartment to achieve its specific goal under the various physiological conditions.

Acute lymphoblastic leukemia with maturation--a new entity with clinical significance

The diagnosis of 'ALL with maturation' (ALLm) is proposed. One hundred and one patients with untreated ALL were entered into this study. The diagnosis of ALLm was made when more than 20% of all nucleated elements in the bone marrow showed maturation beyond prolymphocytes by light microscopic examination. The mature-appearing leukemic cells showed the same immunophenotype to remaining lymphoblasts. The number of ALLm cases was 19 (18.8%). The mean age at presentation of ALLm was 29 +/- 18, older than that of 18 +/- 16 of the remaining typical ALL (ALLt) (P = 0.015). Remission was induced with daunorubicin, vincristine, prednisone and L-asparaginase. Only two of 19 ALLm patients achieved CR after 4 weeks induction chemotherapy. In contrast, 57 of 82 (69.5%) ALLt patients achieved CR after the same induction chemotherapy. There was no significant difference in immunophenotype of ALLm compared with ALLt. Labeling index of DNA topoisomerase IIalpha (TopoLI) was studied by immunohistochemistry. Initial TopoLI of ALLm (221 +/- 147) was much lower than that of ALLt (609 +/- 262, P = 0.005). Furthermore, the remaining leukemic cells after chemotherapy were not labeled with anti-DNA topoisomerase IIalpha. The P53 protein was expressed in nine of 18 ALLm cases (50.0%) and P-glycoprotein was not expressed in ALLm cases. Twelve of 19 ALLm cases were studied for carrying bcr/abl fusion by karyotyping and/or fluorescent in situ hybridization. Only two cases revealed bcr/abl fusion. In conclusion, ALLm is a separate entity of ALL which has a very poor clinical course and is independent of other prognostic factors. The morphologically mature leukemic cells are in resting GO phase.

Isolated bilateral abducens nerve palsy due to carotid cavernous dural arteriovenous fistula

Carotid cavernous dural arteriovenous fistula (DAVF) usually presents with conjunctival injection, proptosis, loss of visual acuity and ophthalmoplegia. There have been some carotid cavernous DAVF case reports presenting with isolated oculomotor, abducens and trochlear nerve palsy. We experienced a patient presenting with bilateral abducens nerve palsy and no other ocular signs who was diagnosed as carotid cavernous DAVF after conventional angiography. According to this case, carotid cavernous DAVF should be considered in the differential diagnosis of isolated bilateral abducens nerve palsy, in which case conventional angiography may be helpful in diagnosis.

Computer-assisted myocardial thickening analysis of gated MIBI SPECT images

RATIONALE AND OBJECTIVES

The purpose of this study is to use the relationship between the partial volume effect, count density, matrix size, and reconstruction filter in gated single photon emission computer tomography (SPECT) to recover myocardial thickness, and to validate measurements generated using a computer-assisted automatic contour method with a phantom model and with thickness changes measured by echocardiography.

METHODS

Regional myocardial contour was defined automatically using shape constraints, gray level thresholding, and a gradient method applied to gated technetium-99m (99mTc)-methoxy-isobutyl-isonitile (MIBI) SPECT images. A heart phantom with wall thickness ranging from 0.8 cm to 1.3 cm was constructed. SPECT images were acquired and reconstructed using different matrix sizes, count densities, and filters. Wall thickness determinations derived from the reconstructions made with each combination of matrix size, type of filter, and cutoff frequency were correlated with the measured thicknesses. The best combination was applied to the gated MIBI SPECT images of 55 patients who also had echocardiography and coronary arteriography. Count density measurements were made across each regional myocardial segment to evaluate wall thickness at end-diastole and end-systole. Systolic wall thickening measurements made with this automated computer-assisted contour technique were compared with echocardiographic measurements made from segments with normal perfusion and from regions containing infarcted tissue.

RESULTS

Different reconstruction filters and cutoff frequencies affected the accuracy of measurements of myocardial wall thickness determined from gated myocardial SPECT images. A matrix size of 64 x 64, with a minimum of 10 counts/pixel/frame, and use of a Hanning filter with 0.5 cyc/cm cutoff frequency gave the best combination for myocardial thickness determination and spatial resolution. Application of these factors to the phantom yielded results that correlated very well with the thickness measurements (r = 0.986, P < 0.001). Application of the technique to the clinical SPECT studies yielded measurements of myocardial wall thickening that were not significantly different from that determined by echocardiography.

CONCLUSION

Computer-assisted contour analysis of gated SPECT images enables accurate determination of regional wall thickening using the count density changes within each myocardial segment.

Prooxidant effects of ferrous iron, hemoglobin, and ferritin in oil emulsion and cooked-meat homogenates are different from those in raw-meat homogenates

Oil emulsion and raw and cooked tissue homogenates were used to determine the mechanisms of various iron forms on the catalysis of lipid peroxidation. Flax oil (0.25 g) was blended with 160 mL maleate buffer (0.1 M, pH 6.5) to prepare an oil emulsion. Raw or cooked turkey leg meat was used to prepare meat homogenates. Samples were prepared by adding iron from each of the various sources, reactive oxygen species, or enzyme (xanthine oxidase and superoxide dismutase) systems into the oil emulsion or meat homogenates. In oil emulsion and cooked-meat homogenates, ferrous iron and hemoglobin had strong prooxidant effects, but ferritin became prooxidant only when ascorbate was present. Hemoglobin and ferritin had no prooxidant effect in raw-meat homogenates. The status of heme iron and the released iron from hemoglobin had little effect on the prooxidant effect of hemoglobin in oil emulsion and cooked meat homogenate systems. The prooxidant effect of ferrous iron in oil emulsion and cooked-meat homogenates disappeared in the presence of superoxide (.O2-), H2O2, or xanthine oxidase systems. In raw-meat homogenates, however, ferrous had strong prooxidant effects even in the presence of .O2-, or H2O2. The status of free iron was the most important factor in the oxidation of oil emulsion and cooked-meat homogenates but the impact in raw-meat homogenates was small.

Ribosomal DNA replication in the fission yeast, Schizosaccharomyces pombe

We have employed genetic and two-dimensional (2D) gel electrophoretic methods to identify replication initiation, pausing, and termination sites in the tandem ribosomal DNA (rDNA) repeats of the fission yeast, Schizosaccharomyces pombe. An autonomously replicating sequence (ARS) element, ars3001, maps to a 2.3-kb restriction fragment spanning the junction between the nontranscribed spacer (NTS) and the external transcribed spacer upstream of the ribosomal RNA genes, and 2D gel analysis shows that replication initiates in the NTS portion of the same fragment. A pause region at the 3' end of the rRNA genes inhibits forks from entering these genes counter to the direction of transcription. Thus, most forks move through the genes in the same direction as transcription. In these respects, fission yeast rDNA replication resembles that in the budding yeast, Saccharomyces cerevisiae, and in multicellular eukaryotic organisms. A feature which, so far, has been detected only in fission yeast is the pausing of replication forks in a broad region near the 5.8S rRNA gene.

DNA cleavage by hydroxyl radicals generated in the Cu,Zn-superoxide dismutase and hydrogen peroxide system

To study the catalytic activity of Cu,Zn-superoxide dismutase (SOD) in the generation of hydroxyl radical (.OH) from H2O2, we investigated the mechanism of DNA cleavage mediated by human Cu,Zn-SOD and H2O2. When plasmid DNA was incubated with 5 microM Cu, Zn-SOD and 1.0 mM H2O2, DNA cleavage occurred within 15 min. A spectrophotometric study using a 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) showed that free .OH formation was proportional to concentrations of Cu,Zn-SOD and H2O2. .OH formation and DNA cleavage were inhibited by hydroxyl radical scavengers such as cyanide, azide, and formate. These results indicated that .OH generated early in the peroxidative reaction of Cu,Zn-SOD with H2O2 was implicated in DNA cleavage. Incubation with H2O2 resulted in a time-dependent release of copper ions from the Cu,Zn-SOD molecule. The released copper ions then likely participated in a Fenton-like reaction to produce .OH that may have caused DNA cleavage. Evidence that DTPA protected the DNA cleavage induced by the Cu,Zn-SOD/H2O2 system supports this mechanism. We suggest that DNA cleavage is mediated in the Cu,Zn-SOD/H2O2 system via the generation of .OH by a combination of the peroxidative reaction of Cu,Zn-SOD and the Fenton-like reaction of free copper ions released from oxidatively damaged SOD.

Fragmentation of human Cu,Zn-superoxide dismutase by peroxidative reaction

We investigated the fragmentation of human Cu,Zn-superoxide dismutase (SOD) by H2O2. When Cu,Zn-SOD was incubated with H2O2, the fragmentation of protein proceeded rapidly within 1 min. The amounts of .OH radical formed in the Cu,Zn-SOD/H2O2 system reached a maximum in about 3 min. This result suggested that .OH was implicated in the fragmentation step. Copper ions released from Cu,Zn-SOD were gradually increased up to 30 min after starting the incubation with H2O2 in a time-dependent manner. However, the fragmentation was not inhibited by 5 mM DTPA. The results suggested that the fragmentation of Cu,Zn-SOD by H2O2 was due to the peroxidative reaction of SOD rather than the Fenton-like reaction by free copper released from oxidatively damaged SOD. A radical scavenger, azide anion, inhibited the fragmentation of Cu,Zn-SOD and the formation of .OH whereas ethanol did not. These results indicated that azide anions had easy access inside the active channel of Cu,Zn-SOD and thus protected the damage of the enzyme by .OH radicals whereas neutral alcohols stayed outside the active channel and could hardly intercept the newly-formed .OH radicals. Thus we conclude that the fragmentation of Cu,Zn-SOD by H2O2, is due to the oxidative damage resulting from free .OH radicals generated by the peroxidative reaction of SOD.

Effect of egg size and strain and age of hens on the solids content of chicken eggs

A study was conducted to determine the effect of egg size and the age and strain of hens on the content of egg solids. Eggs were obtained from commercial farms from four strains of hens with similar age groups and received diets formulated to contain the same dietary energy and protein levels across the strains within a farm. Eggs were collected on 2 different d when the flocks reached the average ages of 28, 55, 75, and 97 wk. The eggs collected form each farm were pooled and sorted by size. Each individual egg was used as a replicate for yolk:white ratio; however, five yolks, five whites, and five whole eggs from each strain at each age period were pooled, homogenized, and then used as a replicate to determine the solids contents of yolk, white, and whole eggs. The yolk:white ratio of eggs from 28-wk-old hens was the lowest, that from 55- and 78-wk-old hens was the highest, and that from 97-wk-old hens was intermediate; however, the solids content (percentage) of whole eggs increased with the age of the hens. The solids content of egg white was highest in eggs from 28-wk-old hens. The white solids content of extra large eggs was greater than that of medium eggs, and yolk solids increased with egg size; however, the solids of whole egg were not affected by egg size. The strain of hens had a significant effect on the solids of whole egg, white, and yolk; however, the strain effect on yolk:white ratio was not significant. The results showed that young (28-wk-old) and old birds (97-wk-old) produced eggs with low solids content and intermediate aged hens (55- to 78-wk-old) produced eggs with high solids content. Therefore, it may be more beneficial for egg producers and processors to use young (28-wk-old) and old birds (97-wk-old) for table egg production and birds of intermediate age (55- to 78-wk-old) for liquid egg production.

Peroxidative activity of human Cu,Zn-superoxide dismutase

In addition to the usual superoxide dismutation activity, Cu,Zn-superoxide dismutase (SOD) has a peroxidative function that utilizes its own dismutation product, H2O2 as a substrate. The peroxidative activity of human Cu,Zn-SOD was studied by using a chromogen, 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) which reacts with OH radicals to form ABTS+. The optimal pH for the peroxidative activity of human Cu,Zn-SOD was 7.6-9.5. The peroxidative activity retained about 50% of the maximum activity when exposed at 40 degrees C for 5 min. The peroxidative activity showed a typical Michaelis-Menten kinetics for ABTS and H2O2 whose K(m) values were 16 microM and 9.3 mM, respectively. The peroxidative activity of human Cu,Zn-SOD was inhibited about 60% by the copper chelator, diethyldithiocarbamate (DDC) at 10 microM while the dismutation activity was not inhibited under a similar condition. We found that there are differences in the effects of temperature and DDC on the dismutation and peroxidative activities of human Cu,Zn-SOD. These results suggest that the amino acid residues which affect the activities of this enzyme may be different between dismutation and peroxidation.

NMR structure determination of a novel conotoxin, [Pro 7,13] alpha A-conotoxin PIVA

A high-resolution solution conformation of a novel conotoxin, [Pro 7,13] alpha A-conotoxin PIVA, GCCGSYPNAACHPCSCKDROSYCGQ-NH2, has been determined by two-dimensional 1H NMR methods and distance geometry calculations. The total of 324 NOE-derived interproton distance restraints including 33 long-range NOE restraints as well as 11 phi and 7 chi 1 torsion angle restraints was used for computation of structures. Back-calculation from the experimental NOE spectrum has provided 49 new NOE restraints and yielded the final R-factors of Ra = 0.641 and Rb = 0.157. The final RMSD values are 0.90 and 1.16 A for the backbone and the heavy atoms, respectively. The C-terminal half of the molecule involving the residues 12-24 is extremely well-defined with a backbone RMSD value of 0.56 A, whereas the N-terminal 3-11 disulfide loop is relatively flexible, possessing a backbone RMSD value of 1.09 A. The [Pro 7,13] alpha A-conotoxin PIVA does not contain any significant secondary structure although the 21S-24G nearly completes one turn of a 3(10) helix. The overall protein fold is largely maintained by the three disulfide bridges of 2-16, 3-11, and 14-23. The presence of the three disulfide bridges imposes geometric constraints that force the molecule to form six continuous bends involving the following residues: 3C-5S, 7P-10A, 12H-14C, 15S-17K, 17K-19R, and 21S-25Q. The overall shape of the [Pro 7,13] alpha A-conotoxin PIVA can be described as an "iron". Residues 15S-19R form a loop that protrudes out of the "bottom plate" formed by the rest of the protein and constitute the handle of the iron. The N-terminal tip of the molecule is relatively immobile due to attractive electrostatic interactions between the gamma-hydroxyl group of 20 Hyp and the phenolic hydroxyl group of 22Y. The flexible 3-11 disulfide loop consists mostly of hydrophobic residues, while the best-defined 14-23 disulfide loop contains the highly charged hydrophilic 15S-19R "handle" domain exposed to the exterior of the protein. Binding to nicotinic acetylcholine receptor can be mediated through two different types of interactions: one involving the aromatic hydrophobic residues such as 6Y and 12H and the other involving the positively charged hydrophilic side chain of the 19R. The side chain of the 19R in the [Pro 7, 13] alpha A-conotoxin PIVA and that of the 9R of the alpha-conotoxin G1, and also the side chains of the 12H and 6Y in the former and those of 10H and 11Y in the latter can be aligned to point to the same direction when the corresponding backbone atoms are superimposed to an RMSD value of 2.5 A.

Chromosomal numerical aberrations in gastric carcinoma: analysis of eighteen cases using in situ hybridization

Paraffin-embedded tumor cells of 18 cases of gastric carcinoma were hybridized with digoxigenin-labeled repetitive DNA probes specific for the centromeric regions of chromosomes X, Y, 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 15, 16, 17, 18, and 20. All cases demonstrated numerical chromosomal aberrations. The most exciting aberration, polysomy (five or more copies) of several chromosomes, was found in all cases except a case of mucinous adenocarcinoma, which showed trisomy 9 as the sole chromosomal numerical aberration. In nine cases of tubular adenocarcinoma, poorly-differentiated polysomies of several chromosomes were the consistent numerical aberration and monosomy 7, 18(2 cases each), 10, and 17(1 case each) were also found. In moderately-differentiated tubular adenocarcinoma all three cases also showed polysomies of several chromosomes. The total number of extra chromosomes (polysomy was counted as 5 copies) was higher in the intestinal type (mean 20.9) than in the diffuse type (mean 14.1). Regional lymph node metastasis, vein invasion, or perineural invasion was not related to any specific chromosomal numerical aberration in gastric cancer. Chromosomes X, 1, 2, 3, 4, 15, 17, and 20 had extra copies especially polysomy in most cases. However, chromosomes 7 and 18 revealed monosomy in many cases (31.3% and 33.3% respectively, and chromosome 9 and 11 revealed trisomy in 35.7% and 75% each. Numerically, the most conserved chromosome in gastric cancer was chromosome 12 (62.5%). By flow cytometry, two diploidy and 8 aneuploidy cases with the DNA indices from 1.30 to 1.85 were found.

Single-photon-emission computed tomography (SPECT) in neurotologic assessment: a preliminary report

The single-photon-emission computed tomography (SPECT) scan enables clinicians to probe dynamic and metabolic changes in brain tissue through measurement of regional cerebral blood flow (rCBF). Diagnostic benefits of the SPECT scan in clinical neurology have been demonstrated. SPECT scanning has been shown to be more sensitive than morphologic imaging techniques [magnetic resonance imaging (MRI) and computed tomography (CT)] in many conditions. However, the use of the scan in assessing neurotologic complaints remains inadequately investigated. Few studies have explored the value of SPECT in establishing the causes of dizziness, hearing loss, and tinnitus. We studied SPECT along with MRI, CT scan, electroencephalogram (EEG), and other evaluations in patients with these neurotologic complaints, SPECT abnormalities were more frequent and prominent than those visualized by other imaging modalities. Overall, 78% of SPECT scans revealed abnormalities. Abnormalities were found in 46% of MRIs, 40% of CTs, and 29% of EEGs. The disparity between SPECT scanning and other procedures was also seen once patients were divided by their chief complaints. This study illustrates the sensitivity of SPECT scanning in evaluating neurotologic complaints and highlights the need for additional research into the importance of SPECT scanning in comprehensive neurotologic evaluation.

Interphase cytogenetics of non-Hodgkin's lymphoma using non-fluorescent in situ hybridization in paraffin embedded tissue

Paraffin-embedded tissue samples from 30 cases of non-Hodgkin's lymphoma(NHL) and 10 of reactive hyperplasia, were processed for interphase cytogenetic chromosomal study. We performed non-fluorescent in situ hybridization(NFISH) using the enzymatic method with digoxigenin-labeled DNA centromeric probes for chromosome 7,12,18 and X, and a painting probe for chromosome 18. Chromosomal aberrations were observed in 27(90%) out of 30 cases of NHL. The most commonly observed numerical aberration was extracopy of X chromosome. There were some characteristic aberrations corresponding to each grade and group of NHL by International Working Formulation: In low grade NHL(9 cases), a third were associated with extracopy of chromosome 12, and disomy X was frequently found in small lymphocytic lymphoma(75%). With intermediate grade(16 cases), tetraploidy(25%), translocation of chromosome 18(25%), and extracopy of chromosome 18(19%) were characteristically associated. These results suggest that interphase NFISH is an easily performable method in retrograde cytogenetic study of archival materials. Some specifically correlated chromosomal aberrations corresponding to the histopathologic grades and groups could provide us more valuable information for determining pathologic diagnosis and assessing the clinical outcome of NHL.

Cytokine transcriptional events during helper T cell subset differentiation

The molecular basis for changes in cytokine expression during T helper (Th) cell subset differentiation is not well understood. We have characterized transcriptional events related to cytokine gene expression in populations of naive T cell receptor-transgenic T cells as they are driven in vitro toward Th1 or Th2 phenotypes by interleukin (IL)-12 or IL-4 treatment, respectively. Quantitative reverse transcriptase-polymerase chain reaction analysis of cytokine transcripts indicates that interferon (IFN) gamma, IL-4, and IL-2 mRNA are expressed with distinct kinetics after naive T cells are stimulated with antigen and either IL-4 or IL-12. IFN-gamma mRNA appears as early as 6 h in IL-12-treated cultures, IL-4 appears only after 48 h in IL-4-treated cultures, and IL-2 is equivalently expressed in both types of cultures. Analyses were performed to determine if there were any differences in activation of IL-2 or IL-4 transcription factors that accompanied Th1 versus Th2 differentiation. These studies demonstrated that signal transducer and activator of transcription 6 (STAT6) binds to a sequence in the IL-4 promoter and that this STAT6-binding site can support IL-4-dependent transcription of a linked heterologous promoter. Prolonged activation of STAT6 is characteristic of populations undergoing Th2 differentiation. Furthermore, STAT6 is activated in an autocrine manner when differentiated Th2 populations are stimulated by antigen receptor ligation. Th1 populations derived from IL-12 plus antigen treatment of naive T cells remain responsive to IL-4 as indicated by induction of STAT6 and IL-4 mRNA. These data indicate that Th1 and Th2 differentiation represents the combination of different, apparently independently regulated transcriptional events. Furthermore, among transcription factors that bind to the IL-4 or IL-2 promoters, STAT6 is the one whose activation distinguishes Th2 versus Th1 development.

Tc-99m MIBI brain SPECT of cerebellopontine angle tumors

To prospectively evaluate the imaging feasibility of Tc-99m sestamibi brain SPECT of cerebellopontine angle (CPA) tumors, seven patients with CPA lesions seen on CT or MRI and five normal control subjects underwent brain SPECT using a triple-headed camera. Five of these patients had acoustic neuromas, one had a meningloma, and the other had a vascular loop. Subsequently, four patients underwent surgery. In normal control subjects and patients with CPA lesions, there was Tc-99m sestamibi activity in the pituitary gland, choroid plexi, and extraocular muscles. The uptake in these structures, especially the choroid plexi could not be blocked by the oral administration of potassium perchlorate in two normal subjects. Four of seven patients with CPA lesions larger than 1.0 cm in diameter showed tumor uptake (3 acoustic schwannomas, 1 meningloma). Two small ( > 1.0 cm in diameter) intracanalicular type acoustic neuromas failed to show uptake, despite additional attenuation correction for the petrous bone. There was no abnormal uptake in the patient with a vascular loop in the CPA. Preliminary data suggest that, with the exception of small intracanalicular neuromas, CPA tumors can be imaged using Tc-99m sestamibi brain SPECT.

Large, complex modular structure of a fission yeast DNA replication origin

BACKGROUND

In the budding yeast, Saccharomyces cerevisiae, each DNA replication origin is associated with an autonomously replicating sequence (ARS) element. Each element contains several modules, including an essential close match to the 11 base-pair (bp) ARS consensus sequence (ACS) and two or three short (< 20 bp) stimulatory motifs, within a stretch of approximately 150 bp or less. To determine whether a similar origin structure exists in the evolutionarily distant fission yeast, Schizosaccharomyces pombe, we used deletion and linker substitution scanning to identify the sequences important for the function of ars3002, a chromosomal replication origin.

RESULTS

We detected two large (30-55 bp) essential regions and several additional stimulatory sequences within a 600 bp stretch of a restriction fragment containing ars3002. The two essential regions are similar to each other, and sequences similar to them are found in all known S. pombe ARS elements, suggesting that one or both of them may represent the S. pombe equivalent of the S. cerevisiae ACS.

CONCLUSIONS

Like S. cerevisiae origins, the S. pombe origin, ars3002, possesses a modular structure, but the number and size of modules is greater for ars3002, and ars3002 is larger than S. cerevisiae origins. These observations suggest that origin function in S. pombe requires more protein-DNA interactions than in S. cerevisiae.

HTLV-I associated adult T cell leukemia/lymphoma: report of two cases from an Amerindian population in coastal northwest British Columbia

Epidemiological studies of HTLV-I infection have demonstrated the presence of this virus in certain Amerindian populations in Central and South America. We have recently reported the first evidence of endemic HTLV-I infection in North American Amerindians from the coastal regions of British Columbia, Canada. While the predominant HTLV-I-associated disease observed in British Columbia Amerindians is the HTLV-I associated neurological disease (HTLV-I-associated myelopathy/tropical spastic paraparesis), we report here the first two cases of HTLV-I-associated adult T cell leukemia/lymphoma (ATL). Clinical and PCR evidence to support the diagnosis of HTLV-I-associated ATL in these two Amerindians is presented. Both cases of ATL were found in the same tribe although neither patient was directly related to each other. While reports of HTLV-I-associated ATL have been reported in Circumartic native peoples, reports of ATL in North American single ancestry Amerindians have not been previously made to our knowledge.

Determination of the three-dimensional structure of hordothionin-alpha by nuclear magnetic resonance

The high-resolution three-dimensional solution structure of the plant toxin hordothionin-alpha obtained from korean barley was determined by using two-dimensional NMR techniques combined with distance geometry and restrained molecular dynamics. Experimentally derived restraints including 292 interproton distances from nuclear Overhauser effect measurements, 16 hydrogen bond restraints together with four disulphide bridge restraints were used as input to calculations of distance geometry and restrained molecular dynamics. Also included in the calculations were 36 phi and 17 chi 1 torsion angles obtained from 33JHN alpha and 3J alpha beta coupling constants in double quantum filtered COSY and primitive exclusive COSY experiments, respectively. The overall protein fold is similar to crambin and purothionin-alpha 1. Two alpha-helices running in opposite directions are found on the basis of 3JHN alpha and 3J alpha beta and deuterium exchange rates for backbone NH protons, and encompass residues 7-18 and 22-28. These two helices are connected by a turn and form a 'helix-turn-helix' motif. A short stretch of an anti-parallel beta-sheet exists between residues 1-4 and 31-34. the two protein termini of hordothionin-alpha are 'well-anchored'; the N-terminus of the protein is immobilized by this short beta-sheet whereas the C-terminus is 'pasted' to the carbonyl group of Cys-4 by a very stable hydrogen bond. The average root-mean-square differences for the backbone and heavy atoms after the restrained molecular dynamics calculations are 0.62 and 1.16 A respectively. These numbers represent a significant improvement over the corresponding values for the previous NMR structures of other thionins. The distance violation from the experimental interproton distances for the final structures is 0.14 for all atoms.

Cystic fibrosis mutation detection by hybridization to light-generated DNA probe arrays

We have combined photochemistry and photolithography with solid-phase DNA synthesis chemistry to form a new technology that makes high density oligonucleotide probe array synthesis possible. Hybridization to these two-dimensional arrays containing hundreds or thousands of oligonucleotide probes provides a powerful DNA sequence analysis tool. Two types of light-generated DNA probe arrays have been used to test for a variety of mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. One array, made up of 428 probes, was designed to scan through the length of CFTR exon 11 and identify differences from the wild type reference sequence. The second type of array contained 1480 probes chosen to detect known deletions, insertions, or base substitution mutations. The validity of the probe arrays was established by hybridizing them with fluorescently labeled control oligonucleotide targets. Characterized mutant CFTR genomic DNA samples were then used to further test probe array hybridization specificity. Finally, ten unknown patient samples were genotyped using the CFTR probe array assay. The genotype assignments were identical to those obtained by PCR product restriction fragment analysis. Our results show that light-generated DNA probe arrays are highly effective in analyzing complex mutation and polymorphism patterns in a relatively large gene such as CFTR.

Systemic lupus erythematosus with obstructive uropathy. Case report and review

We report a case of patient with documented SLE who displayed dysuria, gastrointestinal (GI) symptoms and renal insufficiency associated with the unusual occurrence of bilateral hydroureteronephrosis due to urterovesical junction stricture (obstructive uropathy). Pathologic investigations disclosed chronic interstitial cystitis (IC) with evidence of focal immune complex deposition in the blood vessel walls of the bladder. The GI symptoms and dysuria regressed with initial therapy for SLE with steroids. However, the persistent obstructive uropathy (OU) and renal insufficiency required bilateral nephrostomy followed by steroids plus intravenous pulse injection of cyclophosphamide. The obstructive uropathy was relieved even after removing the nephrostomy tube and renal function remained stable. Including this case, nineteen SLE patients associated with clinical and radiographic findings of OU were found in the world literature and reviewed to find any consistent pattern of clinical features. Most of the patients with OU in SLE were female (mean age, 31.7 yr) and orientals (63%), and had interstitial cystitis (89%) as a common underlying cause with concomitant involvement of the GI tract (89%) and WHO class IV or V advanced glomerulonephritis (67%). Despite the remarkable response (68%) to steroids in majority of OU patients associated with SLE, certain patients still required surgical correction (32%) and some even died (32%). OU, potentially reversible, was not an exception in patients with SLE, which might be overshadowed by other major organ involvement of SLE.

Association of exposure to polycyclic aromatic hydrocarbons (estimated from job category) with concentration of 1-hydroxypyrene glucuronide in urine from workers at a steel plant

OBJECTIVES

Increased risk of lung cancer has been associated with employment in the steel industry. This association is thought to be due in part to increased concentrations of polycyclic aromatic hydrocarbons (PAHs) in air found in this work environment. Measurement of PAH metabolites in human urine provides a means of assessing individual internal dose of PAHs. This study examined the relative contribution of occupation and smoking to urinary concentration of 1-hydroxypyrene glucuronide (1-OHPG) among a group of workers at a steel plant.

METHODS

Concentrations of 1-OHPG in urine from 44 workers with jobs associated with increased air concentrations of PAHs and 40 workers with jobs with low or no exposure to PAHs were measured. 20 workers in each group were not current smokers. Urinary 1-OHPG was measured by synchronous fluorescence spectroscopy after immunoaffinity chromatography specific for PAH metabolites.

RESULTS

Mean (SEM) urinary 1-OHPG concentration was 2.16 (0.42) pmol/ml urine among the 44 occupationally exposed workers compared with 0.38 (0.05) among the 40 workers with no or low exposure (P < 0.0001). Mean urinary 1-OHPG concentration was 1.82 (0.41) pmol/ml urine among the 44 current smokers compared with 0.75 (0.20) among the 40 non-smokers (P < 0.005). Mean 1-OHPG concentrations in non-smokers were 0.26 (n = 20), 0.70 (n = 15), and 2.84 pmol/ml urine (n = 5) for strata of exposure to PAHs (no or low, mid, and high) based on job category; the corresponding values in smokers were 0.55 (n = 20), 0.94 (n = 12), and 4.91 pmol/ml (n = 12), respectively. Multiple linear regression showed significant differences between subjects in different PAH exposure with increased concentrations of 1-OHPG in urine. Amounts of foods containing PAHs ingested by this group of workers were relatively low and did not contribute significantly to urinary 1-OHPG concentrations.

CONCLUSIONS

These results indicate that 1-OHPG is a common urinary metabolite in people with recent occupational exposure to PAHs and is associated with both job category and estimated stratum of PAH exposure.

Prognostic significance of ST-segment depression during adenosine perfusion imaging

To determine the significance of ST-segment depression during adenosine perfusion imaging for predicting future cardiac events, 188 patients with interpretable electrocardiograms were assessed 1 to 3 years (mean 21.5 +/- 6.6 months) after adenosine testing. At least 1 mm of ST-segment depression was observed in 32 (17%) patients, with > or = 2 mm of ST-segment depression in 10 (5.3%). Thirty-seven cardiac events occurred during the study period: 2 cardiac deaths, 5 nonfatal myocardial infarctions, 6 admissions for unstable angina, and 24 revascularizations. Univariate predictors of events were a history of congestive heart failure, previous non-Q-wave myocardial infarction, previous coronary angioplasty, use of antianginal medication, ST-segment depression during adenosine infusion (particularly > or = 2 mm), any reversible perfusion defect, transient left ventricular cavity dilation, and the severity of perfusion defects. Multivariate analysis identified > or = 2 mm ST-segment depression as the most significant predictor of cardiac events (relative risk [RR] = 6.5; p = 0.0001). Other independent predictors of events were left ventricular dilation (RR = 3.8; p = 0.002), previous coronary angioplasty (RR = 3.3; p = 0.001), a history of non-Q-wave myocardial infarction (RR = 2.3; p = 0.01), and the presence of any reversible defect (RR = 2.0; p = 0.05). We conclude that ST-segment depression occurs uncommonly during adenosine infusion, but the presence of > or = 2 mm of ST-segment depression is an independent predictor of future cardiac events and provides information in addition to that obtained from clinical variables and the results of adenosine perfusion imaging.

Delayed radioiodine organification in Plummer's disease

Hyperfunctioning thyroid adenomas causing thyrotoxicosis (Plummer's disease) is not an uncommon cause of hyperthyroidism in the elderly. Most commonly, the adenoma appears as a so-called "hot" nodule on thyroid scintigraphy causing suppression (i.e., nonvisualization) of the remainder of the gland. This report describes a case of Plummer's disease in an elderly patient in whom the toxic nodule primarily responsible for causing the hyperthyroidism became scintigraphically apparent at 96 hours after I-131 therapeutic ablation.

Localization of intracellular monoclonal antibody specific for mycobacteria in experimentally induced pulmonary tuberculous lesion

To determine the intracellular localization of intravenously injected infection-specific monoclonal antibodies (mAbs) in the infected cells, immunohistochemical staining was carried out in an animal model having pulmonary tuberculous lesions induced by inoculation of heat-killed Mycobacterium tuberculosis H37Rv. One milligram of intact mouse mAb against mycobacteria (group I, n = 10) and F(ab')2 (group II, n = 6) was intravenously injected to the rabbits of each group. Immunohistochemical staining using an antimouse Ab was performed at days 1, 3, 5, 7 and 8 in group I and at days 1, 2 and 3 in group II by the streptavidin-biotin method. For the control study, 1 ml of nonspecific polyclonal human IgG (group III, n = 10) and 100 micrograms of normal rabbit IgG F(ab')2 (group IV, n = 6) was injected to rabbits and guinea pigs having tuberculous inflammation, respectively. Both groups (group I and II) showed a positive antigen (Ag)-Ab reaction within the cytoplasm of monocytes. A weak but positive reaction was observed intracellularly in group III; however, no positive reaction was seen in group IV. Our results suggest that an intracellular Ag-Ab reaction plays an important role in the localization of infection by immunoscintigraphy using specific mAb fragments.

Differential inhibition of T and B cell responses to individual antigenic determinants in orally tolerized mice

Immunological tolerance of systemic immunity can be induced by the oral administration of an exogenous antigen, which is termed oral tolerance. We examined whether there was a difference in the degree of tolerance between individual antigenic determinants in oral tolerance. Feeding bovine alpha s1-casein, a major protein in cow's milk, as a constituent of the diet induces oral tolerance in mice. However, a weak antibody response can be elicited in the alpha s1-casein-fed animals by subsequent immunization with the antigen. We examined the fine specificity of such anti-alpha s1-casein antibodies produced in alpha s1-casein-fed mice. The results demonstrated that there was a difference in the inhibition of antibody response between different B cell determinants. Differential inhibition could also be observed for T cell responses. T cells specific for dominant determinants were preferentially tolerized, while those for cryptic determinants escaped oral tolerance. Our results imply the importance of antigen presentation for this differential inhibition of antigenic determinants. We suggest that orally administered antigen does not induce tolerance to some of the B and T lymphocyte repertoire which could potentially induce harmful food hypersensitivity.

Brain SPECT artifact in multidetector SPECT system

Stringent quality control cannot be overemphasized in performing SPECT. SPECT artifacts related to camera uniformity, center of rotation, and the patient's motion are well recognized. In this communication, another rare cause of a SPECT artifact related to a triad system is reported. A triple-headed SPECT system was accidentally equipped with two ultrahigh-resolution collimators and a general all-purpose collimator during a brain SPECT study, causing a false cerebral blood flow defect.

The "count loss" artifact in Tc-99m HMPAO leukocyte SPECT of the abdomen

During SPECT studies of the abdomen with Tc-99m labeled autologous leukocytes, the authors had observed false defects involving the vertebral bodies of the lower thoracic spine in two patients. To investigate this "count loss" artifact, a phantom simulating liver, spleen, and spine was constructed. Four clinical situations were simulated by positioning cylinders in the different locations: normal spine-spleen model, normal liver-spine-spleen model, spine-enlarged spleen model, and enlarged liver-spine-enlarged spleen model. SPECT studies were performed at different concentration ratios between the spleen and the spine on the disparate models with varying distance from the spleen to the spine. The results showed that the count loss artifact is not only related to the concentration ratio between the structures but also is related to the size, position, and distance between the structures. The correction steps for this artifact include: 1) identifying average count value of the spine and spleen from ECT sinogram count data, and 2) replacing the original high-count value in the spleen by the count value close to the average value at the region of the spine in the 120 raw projection data. Using these new modified ECT data, the reconstructed orthogonal images are almost free of the count loss artifact.

Epstein-Barr virus associated posttransplant malignant lymphoma in renal allograft recipients

We report two cases of posttransplant malignant lymphoma(PTML) of B cell origin associated with Epstein-Barr virus(EBV) infection. They were a 52-year-old male and a 37 year-old-female, in whom intermediate-grade diffuse malignant lymphomas of large cell type developed in the submandibular area and jejunum, respectively. DNA and RNA in situ hybridization revealed the presence of EBV-specific DNA and RNA sequences in the tumor cells.

Thyroid scintigraphy of hyperthyroxinemia

The term "hyperthyroxinemia" encompasses clinical syndromes associated with elevated levels of thyroid hormone in the presence of increased, normal, or decreased thyroid function. The clinical presentation (i.e., history and physical examination), in vitro thyroid function tests, as well as radioisotope thyroid imaging all play key roles in the diagnosis of the underlying thyroid disorder. Many of these disorders and their appearance on thyroid scintigraphy are presented in this atlas.