Thymic selection by a single MHC/peptide ligand produces a semidiverse repertoire of CD4+ T cells

The influence of individual peptides in thymic selection was examined in H2-M- mice, in which positive selection is directed to a single peptide, class II-associated invariant chain peptide (CLIP) bound to H2-A(b). Two sensitive in vivo approaches showed that 70%-80% of CD4+ T cells undergoing positive selection to CLIP+H2-A(b) have self-reactivity to the various peptides expressed on wild-type H2-M+ antigen-presenting cells. When these self-reactive T cells were depleted, the residual CD4+ cells displayed a polyclonal repertoire in terms of alloreactivity, responses to foreign protein antigens, and Vbeta usage. Nevertheless, studies with two T cell receptor transgenic lines suggested that the repertoire of CD4+ cells induced by CLIP was less diverse than the repertoire of CD4+ cells in normal mice. Generation of a fully diverse T cell repertoire thus requires positive selection against multiple peptides.

Clinical significance of hepatic visualization on iodine-131 whole-body scan in patients with thyroid carcinoma

The purpose of this study was to evaluate the frequency and clinical significance of diffuse hepatic uptake on 131I whole-body scan in 399 patients (53 males, 348 females) with well-differentiated adenocarcinomas of the thyroid.

METHODS

Two hundred and ninety-one diagnostic scans were performed 2 days after the administration of 74-370 MBq (2-10 mCI) 131I, and 824 post-therapy scans were done 3-5 days after the administration of 1.11-7.4 GBq (30-200 mCI) 131I. There was no evidence of liver metastasis in these patients. Liver and thyroid visualization on each 131I scan were graded from 0-4. To evaluate the incorporation of radioiodine to thyroglobulin and thyroid hormones, a patient's serum was extracted by 80% ethanol/20% trichloroacetic acid solution and analyzed by silica gel thin-layer chromatography.

RESULTS

Diffuse hepatic uptake (> Grade 2) was definitely seen in 239 of 399 (59.9%) of the patients and 397 of 1115 (35.6%) of the studies. In the diagnostic scans, 36 (12.0%) showed uptake in the liver. In post-therapy scans, however, the incidence of liver uptake increased according to increased doses of 131I (39.1% with 1.11 GBq, 61.5% with 2.775-3.7 GBq and 71.3% with 5.55-7.4 GBq). The more that uptake appeared in the residual thyroid, the more it appeared in the liver. There were 13 patients whose scans showed metastatic and liver uptake without any thyroid uptake. Fifteen patients showed diffuse liver uptake without uptake by the thyroid or metastasis. Follow-up studies of seven of these patients revealed metastatic lesions. Liver uptake on scan related to the fraction of 131I-labeled thyroglobulin in the serum.

CONCLUSION

Diffuse liver uptake indicated functioning thyroid remnant or metastasis. In a few cases, liver uptake without uptake by the thyroid or metastasis on whole-body scans suggests hidden metastases.

In vitro and in vivo properties of murine monoclonal antibody for a novel immature thymocyte-differentiated antigen, JL1

JL1 is a novel thymocyte-differentiated antigen strictly confined to stage II immature cortical thymocytes. It is expressed in several types of leukemias and lymphomas. Murine anti-JL1 monoclonal antibody labeled with 131I and 99mTc showed 60-70% of immunoreactivity and 1.4-1.9 x 10(9) L/mol of affinity constant. The incubation of the radiolabeled antibody with Molt-4 cells showed no evidence of modulation or shedding. Localization indices increased from day 3 to day 5 in SCID mice bearing Molt-4 cells.

Improvement of the 3'-5' exonuclease activity of Taq DNA polymerase by protein engineering in the active site

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method. Taq DNA polymerase has a domain at its amino terminus (residue 1 to 291) that has a 5'-3' exonuclease activity, a 3'-5' exonuclease domain in the middle (residue 292 to 423), and a domain at its C-terminus that catalyzes polymerase reactions. Taq DNA polymerase is classified into the polI family which is represented by E. coli DNA polymerase I. The three dimensional structural alignment of 3'-5' exonuclease domains from the polI family, DNA polymerases leads us to understand why Taq DNA polymerase does not carry out proof-reading in the polymerase chain reaction. Three sequence motifs, called ExoI, II, and III must be present in order to carry out proof-reading by the 3'-5' exonuclease reaction in DNA polymerization, but Taq DNA polymerase contains none of them. The key catalytic module in the 3'-5' exonuclease is two metal ions chelated by active-site carboxylic amino acids. In order to render the 3'-5' exonuclease activity in Taq DNA polymerase, a catalytic module was constructured in the active site by protein engineering. The mutant Taq DNA polymerase shows twice as much the 3'-5' exonuclease activity as that of wild-type DNA polymerase.

Cloning and analysis of the DNA polymerase-encoding gene from Thermus caldophilus GK24

The gene encoding Thermus caldophilus GK24 (Tca) DNA polymerase was cloned into Escherichia coli using the structural gene coding for Thermus aquaticus YT-1 (Taq) DNA polymerase as a hybridization probe. The nucleotide sequence of the cloned DNA was determined. The primary structure of the Tca DNA polymerase was deduced from the nucleotide sequence. The Tca DNA polymerase comprised 834 amino acid residues and its molecular mass was determined to be 93,810. On alignment of the whole amino acid sequence, Tca DNA polymerase showed a high sequence homology with the E. coli DNA polymerase I-like DNA polymerases, and 86% identity with Taq DNA polymerase, 38% with E. coli and Streptococcus pneumoniae (Spn) DNA polymerase I. An extremely high sequence identity was observed in the region containing the polymerase activity. The codon usage in the Tca DNA polymerase gene was in fact similar to the characteristic usages in the genes for proteins from bacteria of genus Thermus: the G+C content in the third position of the codons was as high as 93%. The Tca DNA polymerase gene was expressed under the control of tac promoter on a high copy plasmid, pTCA in E. coli.

Regional vascular mechanical properties by 3-D intravascular ultrasound with finite-element analysis

A method employing intravascular ultrasound (IVUS) and simultaneous hemodynamic measurements, with resultant finite element analysis (FEA) of accurate three-dimensional IVUS reconstructions (3-DR), was developed to estimate the regional distribution of arterial elasticity. Human peripheral arterial specimens (iliac and femoral, n = 7) were collected postmortem and perfused at three static transmural pressures: 80, 120, and 160 mmHg. At each pressure, IVUS data were collected at 2.0-mm increments through a 20.0-mm segment and used to create an accurate 3-DR. Mechanical properties were determined over normotensive and hypertensive ranges. An FEA and optimization procedure was implemented in which the elemental elastic modulus was scaled to minimize the displacement error between the computer-predicted and actual deformations. The "optimized" elastic modulus (Eopt) represents an estimate of the component element material stiffness. A dimensionless variable (beta), quantifying structural stiffness, was computed. Eopt of nodiseased tissue regions (n = 80) was greater than atherosclerotic regions (n = 88) for both normotensive (Norm) and hypertensive (Hyp) pressurization: Norm, 9.3 +/- 0.98 vs. 3.5 +/- 0.30; Hyp, 11.3 +/- 0.72 vs. 8.5 +/- 0.47, respectively (mean +/- SE x 10(6) dyn/cm2; P < 0.01 vs. nondiseased). No differences in beta between nondiseased and atherosclerotic tissue were noted at Norm pressurization. With Hyp pressurization, beta of atherosclerotic regions were greater than nondiseased regions: 21.5 +/- 2.21 vs. 14.0 +/- 2.11, respectively (P < 0.03). This method provides a means to identify regional in vivo variations in mechanical properties of arterial tissue.

Cloning and expression of the gene for xylose isomerase from Thermus flavus AT62 in Escherichia coli

The gene encoding xylose isomerase (xylA) was cloned from Thermus flavus AT62 and the DNA sequence was determined. The xylA gene encodes the enzyme xylose isomerase (XI or xylA) consisting of 387 amino acids (calculated Mr of 44,941). Also, there was a partial xylulose kinase gene that was 4 bp overlapped in the end of XI gene. The XI gene was stably expressed in E. coli under the control of tac promoter. XI produced in E. coli was simply purified by heat treatment at 90 degrees C for 10 min and column chromatography of DEAE-Sephacel. The Mr of the purified enzyme was estimated to be 45 kDa on SDS-polyacrylamide gel electrophoresis. However, Mr of the cloned XI was 185 kDa on native condition, indicating that the XI consists of homomeric tetramer. The enzyme has an optimum temperature at 90 degrees C. Thermostability tests revealed that half life at 85 degrees C was 2 mo and 2 h at 95 degrees C. The optimum pH is around 7.0, close to where by-product formation is minimal. The isomerization yield of the cloned XI was about 55% from glucose, indicating that the yield is higher than those of reported enzymes. The K(m) values for various sugar substrates were calculated as 106 mM for glucose. Divalent cations such as Mn2+, Co2+, and Mg2+ are required for the enzyme activity and 100 mM EDTA completely inhibited the enzyme activity.

Involvement of iclR and rpoS in the induction of acs, the gene for acetyl coenzyme A synthetase of Escherichia coli K-12

Two independent pathways in Escherichia coli convert acetate to acetyl CoA: reversal of acetate production by phosphotransacetylase and acetate kinase, and the acetyl-CoA synthetase (Acs) pathway that scavenges acetate. We investigated acs gene expression by using a cat transcriptional fusion. It was observed that acs expression varies depending on the carbon sources used and occurs in the stationary phase of growth even in the absence of acetate. Mutations in iclR for the repressor of the glyoxylate shunt and in rpoS for the stationary phase sigma factor reduced the consumption of acetate mediated by Acs, indicating that both are involved in acs regulation.

Lipoma of the parotid gland

We report two cases of lipoma of the parotid gland which present as a non-tender, freely movable and intraparotid mass. Lipomas are common soft tissue neoplasms but found very rarely in the parotid gland, and so are often not considered in the initial differential diagnosis of parotid gland tumor. We believe that these tumors are cured by simple excision, and thus superficial parotidectomy is enough for treatment.

Superiority of C-11 acetate compared with F-18 fluorodeoxyglucose in predicting myocardial functional recovery by positron emission tomography in patients with acute myocardial infarction

In patients with chronic coronary artery disease, preservation of myocardial oxidative metabolism measured by positron emission tomography (PET) with 11C-acetate is a more accurate predictor of subsequent myocardial functional recovery than is maintenance of glucose metabolism estimated with 18F-fluorodeoxyglucose. However, whether measurements of myocardial oxidative metabolism are more accurate than measurements of glucose metabolism in predicting functional recovery in patients with recent myocardial infarction is unknown. Myocardial oxidative metabolism was measured within 10 days of infarction in 19 patients by analysis of the rate of myocardial clearance of 11C-acetate. Metabolism of glucose was assessed by analysis of the uptake of 18F-fluorodeoxyglucose. Criteria for prediction of the recovery of function based on measurements of oxidative metabolism and glucose metabolism were compared. Threshold criteria with 11C-acetate exhibited superior positive and negative predictive values (89% and 73%, respectively) compared with the criteria of 18F-fluorodeoxyglucose (65% and 57%, respectively) (p <0.025). In addition, the magnitude of functional recovery after revascularization correlated with the severity of the metabolic abnormality present initially. In patients with recent myocardial infarction, the extent of functional recovery can be predicted accurately by measurement of regional oxidative metabolism by PET with 11C-acetate, and these measurements are superior to those of 18-fluorodeoxyglucose.

Purification and characterization of a thermostable ADP-glucose pyrophosphorylase from Thermus caldophilus GK-24

An extremely thermostable ADP-glucose pyrophosphorylase (AGPase) has been purified from Thermus caldophilus GK-24 to homogeneity by chromatographic methods, including gel filtration and ion-exchange and affinity chromatography. The specific activity of the enzyme was enriched 134.8-fold with a recovery of 10.5%. The purified enzyme was a single band by SDS/PAGE with a molecular mass of 52 kDa. The homotetrameric structure of the native enzyme was determined by gel filtration analysis, which showed a molecular mass of 230 kDa on a Superose-12 column, indicating that the structure of the enzyme is different from the heterotetrameric structures of higher-plant AGPases. The enzyme was most active at pH 6.0. The activity was maximal at 73-78 degrees C and its half-life was 30 min at 95 degrees C. Kinetic and regulatory properties were characterized. It was found that AGPase activity could be stimulated by a number of glycolytic intermediates. Fructose 6-phosphate, fructose 1,6-bisphosphate, phenylglyoxal and glucose 6-phosphate were effective activators, of which fructose 1,6-bisphosphate was the most effective. The enzyme was inhibited by phosphate, AMP or ADP. ATP and glucose 1-phosphate gave hyperbolic-shaped rate-concentration curves in the presence or absence of activator. A remarkable aspect of the amino acid composition was the existence of the hydrophobic and Ala+Gly residues. The N-terminal and internal peptide sequences were determined and compared with known sequences of various sources. It was apparently similar to those of AGPases from other bacterial and plant sources, suggesting that the enzymes are structurally related.

Significance of anti-E2 in the diagnosis of HCV infection in patients on maintenance hemodialysis: anti-E2 is frequently detected among anti-HCV antibody-negative patients

A routine screening test used in the diagnosis of hepatitis C virus (HCV) infection is the anti-HCV antibody (anti-HCV) test containing core, NS3, NS4, and NS5 antigens of HCV. When HCV infection occurs in immunocompromised hosts, antibody formation against core, NS3, or NS4 antigens may be weak in the presence of HCV viremia and cannot be detected by routine anti-HCV tests. This study proposed that in immunocompromised hosts such as patients with chronic renal failure (whose capacity to form antibodies is diminished), antibody formation against the E2 region would be preserved, because the E2/NS1 region of HCV is strongly immunogenic. The aim of this study is to evaluate the significance of anti-E2 in the diagnosis of HCV infection among patients on maintenance hemodialysis who are anti-HCV-negative, using a conventional third-generation enzyme immunoassay (EIA) kit. The E2/NS1 gene of HCV encoding the amino acid sequence 388-664 was molecularly cloned into a vector containing an SV 40 promotor and was expressed in Chinese Hamster ovary cells. Using this E2 protein, the anti-E2 test was performed by EIA on 100 patients on maintenance hemodialysis, and on 50 patients with chronic hepatitis C who were anti-HCV-positive, to evaluate the antigenecity of the E2 protein. Of the 100 hemodialysis patients, 15 (15.0%) tested anti-HCV-positive using a third generation anti-HCV ELISA kit. Of the 85 patients who tested negative for anti-HCV, nine (10.6%) were anti-E2-positive and six (66.7%) of these anti-E2 positive patients showed HCV RNA viremia by HCV reverse transcription-polymerase chain reaction. Fourty-two (84.0%) of 50 patients with chronic hepatitis C were anti-E2-positive. As a control group, we tested for anti-E2 among 30 blood donors who were anti-HCV-negative, and also among 85 patients with hepatocellular carcinoma who were anti-HCV-negative, but in both groups, none (0%) was anti-E2-positive. In conclusion, these data suggest that the E2 protein of HCV should be included in a diagnostic anti-HCV kit for the detection of HCV infection in immunocompromised patients.

Distribution of HCV genotypes among blood donors, patients with chronic liver disease, hepatocellular carcinoma, and patients on maintenance hemodialysis in Korea

Hepatitis C virus (HCV) is a single-stranded RNA virus related to the Flaviviridae family, and striking nucleotide sequence diversity has been reported among HCV isolates from different geographic areas. To study the distribution HCV genotypes among disease group in Korea, we subtyped HCV using the method of Okamoto et al. [(1992a): Journal of General Virology 73:673-679] and the reverse hybridization method (INNO-LiPA) on 138 patients who were HCV polymerase chain reaction (PCR)-positive: 30 blood donors, 30 with hepatocellular carcinoma (HCC), 33 with chronic hepatitis, 15 with liver cirrhosis, and 30 patients on maintenance hemodialysis in Korea. In 30 blood donors, HCV genotype 1b was most dominant (80%), followed by genotype 2a (13.3%), and 2b (6.7%). In 30 HCC cases, HCV genotype 1b was less frequent (60%), compared to blood donors, followed by genotype 2a (33.3%), and unclassified (6.7%). In 33 chronic hepatitis cases, HCV genotype 1b was also dominant (63.6%), followed by genotype 2a (30.3%), and 1a (6.1%). In 15 patients with liver cirrhosis, HCV genotype 1b was also dominant (60%), followed by genotype 2a (33.3%), and 1a (6.7%). In 30 patients on maintenance hemodialysis, HCV genotype 1b was dominant (86.7%), followed by genotype 2a (13.3%). In conclusion, among 138 HCV PCR-positive patients, type 1b was the prevailing type (71%), followed by type 2a (23.9%), type 1a (2.1%), type 2b (1.5%), and unclassified (1.5%) in Korea. The prevalence of type 1b in blood donors (80%) was higher than in patients with liver disease (61.5%) and the prevalence of type 1b was the lowest in patients with HCC (60%).

Biotransformation of uridine monophosphate (UMP) and glucose to uridine diphosphate-glucose (UDPG) by Candida saitoana KCTC7249 cells

The present study investigates the biotransformation of glucose with uridine monophosphate (UMP) to obtain sugar nucleotide, UDP-glucose (UDPG), by the dried cells of Candida saitoana KCTC7249. The biotransformation was optimized by varying the concentrations of substrates and phosphate ion. UDPG (24 mM) was biotransformed from 200 mM glucose and 37.5 mM UMP by dried cells of C. saitoana. The glucose yields about 64% UDP-glucose, based on UMP concentration. The addition of glucose-1-phosphate to the reaction mixture accelerated the formation of UDPG from a concentration of UMP. The structure of UDP-glucose obtained was determined with 13C NMR and FAB mass spectra. These results indicate that the yeast-dried cells could be used for the production of nucleotide sugars for donor molecules of complex carbohydrate synthesis.

Prognostic factors of acute myelocytic leukemia: an analysis of 132 patients in a single institution

Patients with acute myelocytic leukemia (AML) have varied outlooks for survival after the diagnosis. To identify pretreatment prognostic indicators in AML, we analyzed 132 cases of AML seen at our hospital between June, 1989 and December, 1994. The median age of the patients was 40 years (range, 15-81). There were 63 male and 69 female patients. One hundred eight patients (82%) received induction chemotherapy which was based on cytarabine plus anthracyclines. Sixty six patients achieved complete remission (CR) and the CR rate among the patients given induction chemotherapy was 61%. The median duration of CR was 11.2 months. After median follow up of 6.6 months (range 0.5-51.4), 26 patients (39%) remain in continuous CR. The median duration of overall survival of the patients was 6.7 months. After median follow up of 10.6 months (range, 0.1-52.7), 41 patients (31%) are alive. Variables affecting duration of CR included the age of the patients, performance status of the patients, percentage of blast in the peripheral blood, hemoglobin level, percentage of blast in the bone marrow, FAB subtype, and CD7 marker positivity. Variables affecting survival duration included age of the patients, performance status of the patients, absolute blast count (ABC) in the peripheral blood, bone marrow cellularity, the percentage of blast in the bone marrow, and CD5 marker positivity. Multivariate analysis showed that the age of the patients and percentage of blast in the bone marrow were significant independent indicators for overall survival of the patients. Further studies utilizing cytogenetics and molecular characteristics of leukemic cell are warranted to better define the prognostic factors of patients with AML.

Quantitative lung perfusion scintigraphy in postoperative evaluation of congenital right ventricular outflow tract obstructive lesions

Improved methods to relieve pulmonary artery stenosis have emphasized the need for an accurate noninvasive method to quantify the pulmonary blood flow. The aim of this study was to compare the roles of Tc-99m MAA perfusion lung imaging, chest x-ray, MRI, and cine-angiography for postoperative evaluation of pulmonary blood flow in patients with congenital right ventricular outflow tract (RVOT) obstructive lesions. Eleven patients underwent chest x-ray, MRI, perfusion lung imaging, and cine-angiography after corrective surgery of RVOT obstruction. The perfusion ratio on lung scans was calculated on the posterior views. The correlation coefficient of the left to right perfusion ratio measured by lung scans obtained with that by visual assessment of chest x-rays, with the most stenotic diameter ratio on MRI and on angiography being 0.57, 0.88 (P < 0.001), and 0.87 (P < 0.001), respectively. Follow-up perfusion lung scans in seven patients, before and after pulmonary artery intervention showed significantly improved perfusion ratios (0.30 +/- 0.11 to 0.70 +/- 0.22; P < 0.001), which were concordant with the clinical findings. The authors conclude that the quantitative perfusion lung scan is the noninvasive method of choice for postoperative evaluation of the pulmonary artery in congenital RVOT obstruction.

Bone marrow scintigraphy using technetium-99m-antigranulocyte antibody in hematologic disorders

Bone marrow is the primary site for many hematologic disorders. To date, however, no suitable bone marrow imaging method has been found. The present study investigates the usefulness of bone marrow immunoscintigraphy using 99mTc-labeled antigranulocyte antibody (anti-NCA-95) in 31 patients with hematologic disorders.

METHODS

One milligram of antibody labeled with 259-370 MBq 99mTc was injected intravenously, and bone marrow images were taken 4 hr later. We also calculated the uptake ratios of lumbar bone marrow-to-background (L/B) and ilium-to-background (I/B).

RESULTS

Of 15 patients with aplastic anemia, 7 showed diffusely decreased antibody uptake (L/B = 2.3 +/- 0.8, I/B = 3.0 +/- 0.8) compared to control patients (n = 21, L/B = 8.2 +/- 2.5, I/B = 10.3 +/- 3.1) Six patients had both decreased and increased uptake areas and two had normal to slightly increased uptake. Of those patients receiving various types of therapy for aplastic anemia, all but one showed increased or irregular uptake. The degree of antibody uptake in the bone marrow correlated with peripheral blood analyses (hemoglobin, white blood cells, platelets). Of six patients with myelodysplastic syndrome, four had irregular uptake and two diffusely decreased uptake. Four patients with myelogenous leukemia showed normal uptake, whereas two with lymphocytic leukemia had decreased uptake. Patients with iron deficiency anemia, pure red cell aplasia or thalassemia minor exhibited normal uptake with bone marrow expansion.

CONCLUSION

Immunoscintigraphy with antigranulocyte antibody is a useful method for evaluating the bone marrow status of patients with various hematologic disorders.

EcoRI variant N199H has enhanced specific activity

The Asn199 residue of the EcoRI restriction endonuclease has been replaced with other amino acids to investigate whether it mediates nucleotide recognition or catalytic activity. Cassette mutagenesis gave variants of EcoRI: N199D, N199H, N199L, N199R, N199S and N199V. Their relative cleavage rates were found to be in the following order: N199H > EcoRI (wild type; wt) > N199L > N199V > N199S > N199R > N199D. In particular, EcoRI variant N199H showed about a twofold higher specific activity than that of the wt enzyme.

Distribution of HCV genotypes among blood donors, patients with chronic liver disease, hepatocellular carcinoma, and patients on maintenance hemodialysis in Korea

Hepatitis C virus (HCV) is a single-stranded RNA virus related to the Flaviviridae family, and striking nucleotide sequence diversity has been reported among HCV isolates from different geographic areas. To study the distribution HCV genotypes among disease group in Korea, we subtyped HCV using the method of Okamoto et al. [(1992a): Journal of General Virology 73:673-679] and the reverse hybridization method (INNO-LiPA) on 138 patients who were HCV polymerase chain reaction (PCR)-positive: 30 blood donors, 30 with hepatocellular carcinoma (HCC), 33 with chronic hepatitis, 15 with liver cirrhosis, and 30 patients on maintenance hemodialysis in Korea. In 30 blood donors, HCV genotype 1b was most dominant (80%), followed by genotype 2a (13.3%), and 2b (6.7%). In 30 HCC cases, HCV genotype 1b was less frequent (60%), compared to blood donors, followed by genotype 2a (33.3%), and unclassified (6.7%). In 33 chronic hepatitis cases, HCV genotype 1b was also dominant (63.6%), followed by genotype 2a (30.3%), and 1a (6.1%). In 15 patients with liver cirrhosis, HCV genotype 1b was also dominant (60%), followed by genotype 2a (33.3%), and 1a (6.7%). In 30 patients on maintenance hemodialysis, HCV genotype 1b was dominant (86.7%), followed by genotype 2a (13.3%). In conclusion, among 138 HCV PCR-positive patients, type 1b was the prevailing type (71%), followed by type 2a (23.9%), type 1a (2.1%), type 2b (1.5%), and unclassified (1.5%) in Korea. The prevalence of type 1b in blood donors (80%) was higher than in patients with liver disease (61.5%) and the prevalence of type 1b was the lowest in patients with HCC (60%).

Genomic organization of purK and purE in Brevibacterium ammoniagenes ATCC 6872: purE locus provides a clue for genomic evolution

From the genomic library of Brevibacterium ammoniagenes ATCC6872, the purE locus encoding 5'-phosphoribosyl-5-aminoimidazole (AIR) carboxylase (EC 4.1.1.21) was cloned and its nucleotide sequence was determined. From the sequence analysis, two distinct open reading frames (ORFs) in the sequence of the purE locus were identified as purK and purE genes (purK-purE). An in vivo translation experiment reconfirmed the purK and purE genes to be independent. The genomic organization in the purE locus of B. ammoniagenes is opposite to that of the bacteria Escherichia coli and Bacillus subtilis. However, it coincides with the fused genes (purKE) of higher organisms Saccharomyces cerevisiae, Schizosaccharomyces pombe and Vigna aconitifolia. This suggests that the purE locus might be an intermediate form for genomic evolution of bacteria to higher organisms.

Intestinal leakage of technetium-99m-MDP in primary intestinal lymphangiectasia

We present a case in which a patient with primary intestinal lymphangiectasia demonstrated abnormal intestinal accumulation of tracer during 99mTc-methylene diphosphonate (MDP) skeletal scintigraphy. Early intestinal leakage with gradual colonic migration and concentration was confirmed by repeat bone scan with serial acquisitions. The mechanism for the intestinal localization of 99mTc-MDP seen in this patient is not clear. Thus, intestinal lymphangiectasia can be a cause for extra-osseous localization of bone scan agents in the intestine.

Role of HLA class II alleles in Korean patients with IDDM

MHC associations with IDDM in the Korean population were studied to investigate genetic susceptibility to this disorder. The frequencies of HLA-DR3, -DR4 and -DR9 were significantly higher in diabetic patients. However, the frequency of DR2 was significantly decreased in diabetic patients. DQA1*0301 and DQA1*0501 were positively and DQA1*0102 and DQA1*0201 negatively associated with IDDM. DQB1*0301 and DQB1*0601 were negatively associated with IDDM. Heterodimers DQA1*0301-DQB1*0201, DQA1*0501-DQB1*0201 and DQA1*0501-DQB1*0302 were positively associated with DQA1*0102-DQB1*0601 negatively associated with IDDM. The frequencies of DR3-DQA1*0301-DQB1*0201 and -DQA1*0501-DQB1*0201 were significantly higher in diabetic patients. The frequencies of DR4-DQA1*0301-DQB1*0201 and DR9-DQA1*0301-DQB1*0303 were significantly higher in diabetic patients. The presence of non-aspartic acid at position 57 of the DQ beta-chain was not associated with susceptibility to IDDM. However, the frequency of Arg 52 homozygotes was significantly higher in diabetic patients. These results suggest a role of the MHC molecule and also suggest racial differences in susceptibility to IDDM even within the Asian populations.

1,2-O-(Ethane-1,2-diyl)-α-D-glucofuranose. Crystal Structure, and the Stereochemistry of Related Bicyclic Acetal Analogues

Crystalline 1,2-O-(ethane-1,2-diyl)-α-D- glucofuranose (9) is orthorhombic, P 21212, with a = 17.702(4), b = 8.892(2), c = 5.6400(9) Ǻ, Z = 4, R = 0.050, and Rw = 0.041. The conformation of the 1,4-dioxan ring in this bicyclic acetal is slightly distorted from 7C1, and that of the glucofuranose ring is intermediate between the 3E and 3T2 conformations. Extensive intermolecular hydrogen-bonding of exocyclic OH(5) and OH(6) dominates the solid state interactions. In aqueous solution, compound (9) retains close to the same stereochemical characteristics as in the crystal, including those of the exocyclic C(4)-C(5)-C(6) segment of the molecule, according to n.m.r. spectroscopic evidence. These findings provide support for the structures assigned to related bicyclic acetals (7) and (8), which differ from (9) in having a methyl substituent at C(8) on their 1,4-dioxan rings, notably in confirming that the configuration at C(8) is R in (7) and S in (8).