NMR with (13)C, (15)N-doubly-labeled DNA: The shape Antennapedia homeodomain complex with a 14-mer DNA duplex

Nearly complete (1)H, (13)C and(15) N NMR assignments have been obtained for a doubly labeled 14-base pair DNA duplex in solution both in the free state and complexed with the uniformly (15)N-labeled Antennapedia homeodomain. The DNA was either fully (13)C,(15)N-labeled or contained uniformly (13)C, (15)N-labeled nucleotides only at those positions which form the protein-DNA interface in the previously determined NMR solution structure of the Antennapedia homeodomain-DNA complex. The resonance assignments were obtained in three steps: (i) identification of the deoxyribose spin systems via scalar couplings using 2D and 3D HCCH-COSY and soft-relayed HCCH-COSY; (ii) sequential assignment of the nucleotides via(1) H-(1)H NOEs observed in 3D(13) C-resolved NOESY; and (iii) assignment of the imino and amino groups via (1)H-(1)H NOEs and(15) N-(1)H correlation spectroscopy. The assignment of the duplex in the 17 kDa protein-DNA complex was greatly facilitated by the fact that (1)H signals of the protein were filtered out in (13)C-resolved spectroscopy and by the excellent carbon chemical shift dispersion of the DNA duplex. Comparison of corresponding (13)C chemical shifts of the free and the protein-bound DNA indicates conformational changes in the DNA upon complex formation.

Proteoglycans in the nucleus pulposus of canine intervertebral discs after chondroitinase ABC treatment

Experimental chemonucleolysis of the canine intervertebral disc with chondroitinase ABC and chymopapain was compared during a 52-week period. Roentgenograms and magnetic resonance imaging were used to examine changes in disc space and water content, respectively. Disc space narrowing and reductions in disc water content after chondroitinase ABC treatment were less than that after chymopapain. High-performance liquid chromatography was performed to measure changes in proteoglycans. Similarly to chymopapain, chondroitinase ABC degrades proteoglycans in the nucleus pulposus and decreases their quantity. However, large differences in the molecular weight and acidity of the resynthesized proteoglycans and in the chain length of the resynthesized glycosaminoglycans were observed between the two enzymes. The difference in disc space narrowing and the changes in disc water content between the two enzymes might result from differences in the characteristics of the resynthesized proteoglycans.

Provirus load in patients with human T-cell leukemia virus type 1 uveitis correlates with precedent Graves' disease and disease activities

We previously demonstrated the increased provirus load in the peripheral blood of patients with human T-cell leukemia virus type 1 (HTLV-1) uveitis (HU). To delineate the relevance of the increased provirus load to clinical and immunologic parameters, we studied the correlation between them. Seventy-nine HU patients (24 male and 55 female) were included in the study, with their informed consent. Plasma samples and genomic DNA of the peripheral blood mononuclear cells were isolated and the provirus load was estimated by semi-quantitative polymerase chain reaction of the gag region sequence. Serum levels of anti-HTLV-1 antibodies and soluble IL-2R were determined by electrochemiluminescence immuno assay and by ELISA, respectively. Disease activities were assessed and graded 0 to 4 according to the evaluation system. Recurrence of the disease during the follow-up period was diagnosed ophthalmologically. The provirus load was significantly higher in the HU patients after Graves' disease (GD) than in those without GD (P<0.05). It correlated with disease activities assessed in terms of vitreous inflammation and interval to recurrence (both P<0.05). In the HU patients without GD, it correlated with the serum levels of soluble IL-2 receptor (P<0.01), and nearly with those of HTLV-1 antibody (P=0.063). These correlations were not found in the HU patients after GD under methimazole treatment. The results suggested a direct involvement of HTLV-1-infected cells in the pathogenesis of uveitis, and raise the possibility that hyperthyroidism may contribute to the clonal expansion of HTLV-1-infected cells.

Synthesis of stereoselectively 13C/2H-doubly labeled DNA oligomers by the combined use of chemical and enzymatic reactions

(2'S,5'S)-(1',2',3',4',5'-13C5;2',5'-2H2-thymidine, prepared via labeled ribosyl thymidine as described in the accompanying paper, has been successfully converted into isotopically labeled dA, dG, and dC using enzymatic transdeoxyribosylation reactions.

Synthesis of stereoselectively 5'-monodeuterated nucleoside with defined S/R-ratios. An application to the assignment of 5'-methylene signals of DNA oligomers

A method to prepare 5'-monodeuterated nucleosides with various S/R-ratios is described. 5-Oxopentose derivatives synthesized from glucose were converted into 5-monodeuterated pentose derivatives by LiAID4 in the presence of various ligands. The stereoselectivities of the deuteration reactions were investigated under a variety of conditions, and the S/R-ratios of the 5-monodeuterated pentoses varied from 4 : 1 to 1 : 7.4. By mixing these 5-monodeuterated pentose derivatives, we have successfully synthesized thymidine with a defined S/R-ratio at C5'.

Selective multiple labeling strategy to obtain accurate NMR parameters for nucleic acids. Conformational analysis around the glycosidic bond

A systematic synthesis of pyrimidine nucleosides with 13C-labels only at specific atoms in both the base and sugar moieties has been developed in order to obtain conformational information about the glycosidic bond through measurement of the accurate vicinal coupling constants between H1' and C2/C6. For this purpose, 13C labels at three positions, namely C1', C2, and C6, are essential. We have synthesized selectively multiply labeled nucleosides, such as [2, 1'-13C2]-thymidine, [2, 1'-13C2]-2'-deoxycytidine, [6, 1'-13C2]-thymidine, and [6, 1'-13C2]-2'-deoxycytidine. These nucleosides will be useful to determine the relative orientation of the base and sugar moieties.

Structure model and physicochemical properties of the C-U mismatch pair in the double stranded RNA in solution

Structure of the C-U mismatch pair was reported only in crystal but none in solution. Here we have studied the structure and physicochemical properties of the C-U mismatch pair in a double stranded RNA in solution. RNA oligomers r(CGACUCAGG) and r(CCUGCGUCG) form a double stranded structure with the C-U pair. The arrangement of the C-U pair derived from the model building based on nOe gives a similar structural feature to that in crystal. The modeling reveals that the amino-proton of cytidine and the keto-oxygen of uridine are located within hydrogen bonding distance, and the imino proton of uridine is exposed to bulk water. From the melting experiment which monitors chemical shifts of non-exchangeable protons, the melting of all the base-pairs including the C-U pair occurs simultaneously. This suggests the possibility where the C-U mismatch pair is stacked on the neighboring base-pairs in the double helix until the duplex is denatured to single strands.

X-ray analysis of DNA dodecamer containing 2'-deoxy-N6-methoxyadenosine

Oxyamines have been known as a mutagen which attacks amino groups of DNA bases. It is expected that the modified adenine derivative has a tautomer which can form a stable base pair not only with thymine but also with cytosine. For establishing such tautomerization mutagenesis, we have solved a crystal structure of DNA dodecamer containing 2'-deoxy-N6-methoxyadenosine. It is shown that the N6-methoxyadenine takes a imino form to form a Watson-Crick type pairing with cytosine in the DNA duplex.

[Estimated prevalence rate of HTLV-I uveitis in Chikugo]

To estimate the prevalence rate of human T-cell lymphotropic virus type 1 (HTLV-I) uveitis, an epidemiological survey was carried out in the Chikugo District of Fukuoka Prefecture between 1 September and 31 October 1995. The survey was done by sending questionnaires on uveitis patients to all ophthalmological institutes in the district and measuring the serum antibody to HTLV-I. The recovery rate of the survey was 39 of 48 institutes (81.3%). A total of 357 patients with uveitis were reported in the survey, of whom 317 (88.8%) were tested for their seropositivity to HTLV-I. Among them, 18 patients were counted as having HTLV-I uveitis (HU) on 1 October 1995. Based on these data together with the age- and sex-specific population of HTLV-I carriers in the Chikugo District, it was estimated that the crude prevalence rates of HU per 100,000 HTLV-I carrier population were 58.6 in males, 152.0 in females, and 112.2 in both sexes. The prevalence rate of HU was slightly higher than that of HTLV-I associated myelopathy.

Development of glycosylated human interleukin-1alpha, neoglyco IL-1alpha, coupled with D-galactose monosaccharide: biological activities in vivo

In our previous study, a galactose monosaccharide with C9 spacer was chemically coupled to recombinant human interleukin 1alpha (rhIL-1alpha) in order to study the effect of glycosylation on its activities, and to develop IL-1 with less deleterious effects. The glycosylated IL-la exhibited reduced activities in vitro by 10 to 10000-fold depending upon different aspects of activities addressed. The affinity to type I and II IL-1 receptors were also reduced. In this study we examined a variety of IL-1 activities in vivo, including upregulation of serum levels of IL-6, alpha1-acid glycoprotein, NOx, corticosterone, downregulation of serum level of glucose, and recovery of peripheral white blood cells (WBCs) from myelosuppression in 5-fluorouracil-treated mice. In contrast to the biological activities in vitro, these activities in vivo were uniformly reduced by only about 10 to 20-fold compared to untreated IL-1alpha.

Role of matrix in an early postentry step in the human immunodeficiency virus type 1 life cycle

The matrix protein of human immunodeficiency virus type 1 (HIV-1) has been reported to play a crucial role in the targeting of the Gag polyprotein precursor to the plasma membrane and in the incorporation of viral envelope glycoproteins into budding virions. In this report, we present evidence that mutation of a highly conserved Leu at matrix amino acid 20 blocks or markedly delays virus replication in a range of cell types, including T-cell lines, primary human peripheral blood mononuclear cells, and monocyte-derived macrophages. These mutations do not impair virus assembly and release, RNA encapsidation, or envelope glycoprotein incorporation into virions but rather cause significant defects in an early step in the virus life cycle, as measured by single-cycle infectivity assays and the analysis of viral DNA synthesis early postinfection. This infectivity defect is independent of the type of envelope glycoprotein carried on mutant virions; similar results are obtained in pseudotyping experiments using wild-type or truncated HIV-1 envelope glycoproteins, the amphotropic murine leukemia virus envelope, or the vesicular stomatitis G protein. Intriguingly, matrix residue 20 mutations also increase the apparent binding of Gag to membrane, accelerate the kinetics of Gag processing, and induce defects in endogenous reverse transcriptase activity without affecting virion density or morphology. These results help elucidate the function of matrix in HIV-1 replication.

Characteristics of cardiac hypertrophy in the juvenile visceral steatosis mouse with systemic carnitine deficiency

The juvenile visceral steatosis (JVS) mouse exhibits hereditary systemic carnitine deficiency and develops cardiac hypertrophy. The aim of this study was to clarify the characteristics of cardiac hypertrophy in the JVS mouse. Total carnitine content in IVS mouse heart was about 10% of that of control mouse heart at 4 and 8 weeks of age. The heart weight/body weight ratio was bigger in JVS mice than that in control mice at 2 weeks of age, and this difference in ratio increased with age. The wall areas of both ventricles and septum in JVS mice were larger than those of the control mice at 2 and 8 weeks. The myocyte diameter in both ventricular walls and septum in JVS mice was longer than that of the control mice. On electron microscopy, the percent of mitochondria in the myocyte was 66% in JVS mice, and 37% in control mice. The percent of lipid fraction in JVS mice was six-fold higher than that in control mice. Total content of adenine nucleotides in JVS mouse heart was about 60% of that in control mouse heart. Adenylate energy charge in JVS mouse heart was 63 and 45% of that in the control mouse heart at 4 and 8 weeks, respectively. Overall, the cardiac enlargement observed in this animal model could be accounted for by a proportional increase in the myocyte diameter in the ventricles and septum, accompanied by an increase in mitochondria. Furthermore, this cellular growth is associated with decreases in the levels of ATP and ADP, and adenylate energy charge.

Mutation/polymorphism scanning of glucose-6-phosphatase gene promoter in noninsulin-dependent diabetes mellitus patients

Glucose-6-phosphatase (G6Pase) catalyzes the rate-limiting step of gluconeogenesis, and hepatic G6Pase activity is increased in diabetes. We have cloned and analyzed the human G6Pase gene promoter region and identified putative regulatory sequences for insulin, cAMP, glucocorticoid, and hepatocyte nuclear factors. The promoter region of the G6Pase gene was analyzed in 154 noninsulin-dependent diabetes mellitus patients and 90 control subjects by PCR-single strand conformation polymorphism and direct sequencing methods. Polymorphisms were not found in any subjects. The results suggested that in noninsulin-dependent diabetic patients, the major cause of the hepatic glucose overproduction was not attributed to dysregulation of the G6Pase gene due to mutation/polymorphism of its promoter region.

Nucleotide sequencing analysis of the 146-kilobase segment around the IkBL and MICA genes at the centromeric end of the HLA class I region

To elucidate the complete gene structure and to identify new genes involved in the development of HLA class I antigen-associated diseases in the class I region of the human major histocompatibility complex on chromosome 6, a YAC clone (745D12) covering the 146-kb segment around the IkBL and MICA loci was isolated from a YAC library constructed from the B-cell line, BOLETH. A physical map of this region was constructed by isolation of overlapping cosmid clones derived from 745D12. Of these, five contiguous cosmids were chosen for DNA sequencing by the shotgun strategy to give a single contig of 146,601 bp from 2.8 kb telomeric of the IkBL gene to exon 6 of MICA. This region was confirmed to contain five known genes, IkBL, BAT1, MICB, P5-1, and HLA-X (class I fragment), from centromere to telomere, and their exon-intron organizations were determined. The 3.8-1 homologue gene (3.8-1-hom) showing 99.7% identity with the 3.8-1 cDNA clone, which was originally isolated using the 3.8-kb EcoRI fragment between the HLA-54/H and the HLA-G genes, was detected between MICA and MICB and was suggested to represent the cognate 3.8-1 genomic sequence from which the cDNA clone was derived. No evidence for the presence of expressed new genes could be obtained in this region by homology and EST searches or coding and exon prediction analyses. One TA microsatellite repeat spanning 2545 bases with as many as 913 repetitions was found on the centromeric side of the MICA gene and was indicated to be a potential hot spot for genetic recombination. The two segments of approximately 35 kb upstream of the MICA and MICB genes showed high sequence homology (about 85%) to each other, suggesting that segmental genome duplication including the MICA and MICB genes must have occurred during the evolution of the human MHC.

Mitochondrial abnormalities in a murine model of primary carnitine deficiency. Systemic pathology and trial of replacement therapy

Mitochondrial abnormalities and effectiveness of replacement therapy were examined in a murine model of systemic carnitine deficiency, namely the juvenile visceral steatosis (JVS) mouse. Homozygous JVS mice revealed severe lipid deposition and abnormal mitochondria in liver, heart, skeletal muscle, and kidney, but there was no pathological change in the nervous system, though they showed cerebral signs. There were numerous ragged-red fibers in muscles, but enzyme activities of the respiratory chain were intact. Histograms of oxidative and nonoxidative muscle fibers showed an increase in small and oxidative muscle fibers in 4-week-old JVS mice, but this difference no longer existed in 8-week- or 1-year-old JVS mice. On the contrary, Mn-superoxide dismutase immunostaining of muscle showed a focal increase in every age of JVS mice. With L-carnitine treatment, JVS mice could survive for a year, but to some extent, there were the same pathological changes as those seen in untreated mice.

[Human T-lymphotropic virus type 1 uveitis in children]

We report here five pediatric patients with human T-lymphotropic virus type 1 (HTLV-I) uveitis. The patients were one boy and four girls aged between 3 and 14 years. The transmission route was considered to be breast feeding from their mothers. All patients had unilateral uveitis and the ocular symptoms were similar to those in HTLV-I uveitis in adults. The ocular inflammation responded to therapy with topical or systemic corticosteroids, but recurred in three patients. HTLV-I provirus DNA was detected by polymerase chain reaction (PCR) from infiltrating cells in the anterior chamber in one patient. The percentage of HTLV-I-infected cells in the peripheral blood mononuclear cells was measured by quantitative PCR, and the values were high (2.9 approximately 7.3%) in three cases tested as compared with an asymptomatic carrier. These five cases show that HTLV-I uveitis can be induced in a relatively short period (3 approximately 10 years) after the viral infection, and that HTLV-I uveitis should be considered as one possible etiology of uveitis in children, particularly in a viral endemic area.

Characterization of human immunodeficiency virus type 1 matrix revertants: effects on virus assembly, Gag processing, and Env incorporation into virions

The matrix protein of human immunodeficiency virus type 1 (HIV-1) has been postulated to serve a variety of functions in the virus life cycle. Previously, we introduced a large number of mutations into the HIV-1 matrix and determined the effects on virus replication. These studies identified domains involved in virus assembly and release and envelope glycoprotein incorporation into virions. Here we describe the identification and characterization of viral revertants containing second-site changes in the matrix which compensate for the effects of four of the original mutations on matrix function. Specifically, mutations at matrix residues 4 and 6 severely impaired virus assembly and release; substitutions at residues 4 and 6 reversed the phenotype of the amino acid 4 change while second-site mutations at matrix positions 10, 69, and 97 partially or fully reversed the phenotype of the amino acid 6 substitution. A mutation at matrix residue 62 reversed the effect of a position 34 change which blocks envelope glycoprotein incorporation into virions, and substitutions at residues 27 and 51 reversed the phenotype of a position 86 mutation which redirects virus assembly to the cytoplasm. In addition to determining the effects of the compensatory changes in the context of the original mutations, we also introduced and analyzed the second-site changes alone in the context of the wild-type molecular clone. The data presented here define potential intermolecular and intramolecular interactions which occur in the matrix during the virus life cycle and have implications for our understanding of the relationship between matrix structure and function.

Nucleotide sequence analysis of the HLA class I region spanning the 237-kb segment around the HLA-B and -C genes

To elucidate the detailed gene organization of the human leukocyte antigen (HLA) class I region on chromosome 6, seven contiguous cosmid genomic clones covering the 237-kb segment around the HLA-B and -C loci were subjected to DNA sequencing by the shotgun strategy to give a single contig of 236,822 bp from the MICA gene (58.2 kb centromeric of HLA-B) to 90.8 kb telomeric of HLA-C. This region was confirmed to contain four known genes, MICA, HLA-17, HLA-B, and HLA-C, from centromere to telomere. Further, a new member of the P5 multicopy genes was found to be about 1.3 kb upstream of the HLA-17 gene and designated P5.8. Five novel genes designated NOB1-5 were identified by RT-PCR and Northern blot hybridization. In addition, two pseudogenes, dihydrofolate reductase pseudogene (DHFRP) and ribosomal protein L3 homologous gene (RPL3-Hom), were also found in the vicinity of the HLA-B and -C genes, respectively. The two segments (about 40 kb) downstream of the HLA-B and HLA-C genes showed high sequence homology to each other, suggesting that segmental genome duplication including the major histocompatibility complex (MHC) class I gene must have occurred during the evolution of the MHC.

Nucleosides and nucleotides. 160. Synthesis of oligodeoxyribonucleotides containing 5-(N-aminoalkyl)carbamoyl-2'-deoxyuridines by a new postsynthetic modification method and their thermal stability and nuclease-resistance properties

Heptadecadeoxynucleotides containing 5-(N-aminoethyl- or N-aminohexyl)carbamoyl-2'-deoxyuridines (E or H) were synthesized using a newly developed postsynthetic modification method. As a convertible nucleoside unit, 5-methoxycarbonyl-2'-deoxyuridine (1) was initially incorporated into oligodeoxynucleotides (ODNs) according to the phosphoramidite method at various positions using a DNA synthesizer. Fully protected ODNs attached to a solid support were treated with alkyldiamines such as ethylenediamine and 1,6-hexanediamine to give the above modified ODNs. The thermal stability, resistance toward nuclease digestion, and stability in fetal calf serum of the modified ODNs were studied. An increase in the number of 5-(N-aminohexyl)carbamoyl-2'-deoxyuridines (H) in the ODNs was found to effectively stabilize duplex formation with both the corresponding complementary DNA and RNA and protect against nucleolytic hydrolysis by snake venom phosphodiesterase. In particular, the half-life of ODN 19, which contained four H residues, was about 162 h in the presence of the nuclease. Furthermore, 19 was also stable in medium containing 10% fetal calf serum with a t1/2 of about 48 h, while t1/2 for the corresponding unmodified ODN was 13 min.

NMR analysis of the hydrogen bonding interactions of the RNA-binding domains of the Drosophila sex-lethal protein with target RNA fragments with site-specific [3-15N]uridine substitutions

It has been reported that a 183 residue fragment, consisting of the two RNA-binding domains (RBD1- RBD2) of the Drosophila melanogster Sex-lethal (Sxl) protein, strongly binds an oligonucleotide of the target RNA sequence (5'-GUUUUUUUUC-3') that regulates alternative splicing, and forms four or five hydrogen bonds with the imino groups of the RNA. In the present study, we used site-directed mutagenesis to improve the solubility of the didomain fragment of Sxl, and confirmed that this mutant fragment forms hydrogen bonds with the target RNA in the same manner as that of the wild-type fragment. The mutant fragment was shown to bind the cognate RNA sequences GUUUUUUUUC and AUUUUUUUUC more tightly than UUUUUUUUC. By using a [3-15N]uridine phosphoramidite, we synthesized a series of15N-labeled target RNAs, in which one of the uridine residues was specifically replaced by [3-15N]uridine. By observing the imino1H-15N coupling of the labeled uridine residue, we assigned all four of the hydrogen-bonded imino protons to U1, U2, U5 and U6, respectively, of the target RNA. The imino protons of U2 and U6 exhibited nuclear Overhauser effects with aliphatic protons of the protein. All these results indicate that the A/G, U1, U2, U5 and U6 residues in the target sequence of (G/A)UUUUUUUU are specifically recognized by the two RNA-binding domains of the Sxl protein.

Immunologic and virologic characterization of the primary infiltrating cells in the aqueous humor of human T-cell leukemia virus type-1 uveitis. Accumulation of the human T-cell leukemia virus type-1-infected cells and constitutive expression of viral and interleukin-6 messenger ribonucleic acids

PURPOSE

To characterize immunologically and virologically the infiltrating cells in the aqueous humor of patients with human T-cell leukemia virus type-1 (HTLV-1) uveitis (HU).

METHODS

With their informed consent, patients had 0.1 ml of the aqueous humor in the anterior chamber collected with a needle under an operating microscope. An aliquot of the collected sample from patients without steroid therapy was examined by May-Giemsa staining and immunocytochemically. The presence of the HTLV-1-infected cells was investigated by polymerase chain reaction (PCR) using the gag and pol regions of the provirus genome. The population of the infected cells was compared by PCR testing the amplification of the virus genome from 60 cells, or determining the endpoint of successful amplification of the twofold dilution series of the samples, collected from the aqueous humor and peripheral blood mononuclear cells (PBMCs), which were obtained at the same time. Expression of viral and cytokine genes was studied by reverse transcriptase-PCR (RT-PCR). The interleukin-6 (IL-6) level in the aqueous humor of patients with HU and control subjects was measured by a high-sensitivity enzyme-linked immunosorbent assay kit.

RESULTS

The number of the infiltrating cells ranged from 475 to 3563 (mean = 2111) per 0.1 ml of aqueous humor, and all the identifiable cells were lymphocytes. Most of them were CD3-positive T cells (mean = 78%), whereas CD4-positive cells constituted less than half (mean = 35.3%). HTLV-1 provirus was detected by PCR in the infiltrating cells of 36 of 38 patients with HU tested, whereas it was detected in 1 of 4 seropositive patients with other entities of uveitis. A higher population of the infected cells in the aqueous humor than in the PBMC was found in seven of nine patients with HU by two independent approaches. Expression of HTLV-1 env or pX genes or both was shown in all 12 patients with HU tested by RT-PCR. IL-6 messenger ribonucleic acid (mRNA) was detected by RT-PCR in 10 of these 12 patients, whereas those of interleukin-1 alpha, interleukin-2, interleukin-4, and tumor-necrosis factor-alpha were not, and that of interferon-gamma was detected in only 1 patient. The IL-6 level was elevated significantly in the aqueous humor of nine patients with HU compared with that of five control subjects (520.2 +/- 841 pg/ml versus 2.77 +/- 1.59 pg/ml, P < 0.01 by Mann-Whitney test).

CONCLUSIONS

HU is characterized by lymphocytic infiltration with a predominance of T cells and by the presence and probable accumulation of HTLV-1-infected lymphocytes in the affected eye. Production of viral antigens and IL-6 by the infiltrating cells could be responsible for the development of HU.

Differential central modulation of the baroreflex by salt loading in normotensive and spontaneously hypertensive rats

In salt-sensitive hypertensive animal models and human subjects compared with their salt-resistant counterparts, sympathetic activity is abnormally enhanced during a high salt diet. We examined whether salt loading differentially modulates the arterial baroreceptor reflex (ABR), a major control mechanism of arterial pressure and sympathetic vasomotor activity, in young normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Six-week-old WKY and SHR were fed a normal (0.66%) or high (8.00%) salt diet for 4 weeks. After the diet regimen, baseline levels of mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA), and the overall and central properties of the ABR were compared among the four groups of rats under halothane anesthesia. In WKY, a high salt diet did not affect baseline arterial pressure and RSNA but potentiated the ABR, as evidenced by an increase in the maximal slope of MAP-RSNA and MAP-heart rate relationships. In SHR, by contrast, salt loading accelerated hypertension and sympathetic overactivity and impaired the ABR. Salt-induced modulation of the ABR was associated with that of the central property, since reflex inhibition of RSNA by stimulation of the aortic depressor nerve was augmented in WKY and attenuated in SHR. These results suggest that differential modulation of the central mechanism subserving the baroreflex control of sympathetic activity at least partly accounts for the difference in salt sensitivity between WKY and SHR.

Reactions between hydroxyl-radical-induced 7,8-dihydro-8-oxo-2'-deoxyguanosine precursor and the spin trap alpha-phenyl-N-tert-butylnitrone

An N2O-saturated aqueous solution containing 2'-dG and the spin trap agent PBN was examined by ESR and HPLC-ECD methods after X irradiation. ESR examination showed that the ESR spectrum obtained consisted of signals due to the PBN-OH and PBN-H adducts. The signal intensity of PBN-H adducts was larger in the presence of 2'-dG than in the absence of 2'dG, while that of PBN-OH adducts was smaller in the presence of 2'-dG than in the absence of 2'-dG. When the OH-radical-induced 8-oxodG was measured by HPLC-ECD, the yield of 8-oxodG was found to be enhanced about twofold in the presence of PBN. By contrast, usual OH-radical scavengers (DMSO, sodium formate and mannitol) inhibited the formation of 8-oxodG beyond expectation. The enhancement of the yield of PBN-H adducts by 2'-dG and the enhancement of the 8-oxodG formation by PBN were explained by the electron transfer and subsequent proton transfer reactions from OH-radical-induced guanine-N7 radicals to PBN to form 8-oxodG and PBN-H. The present study led us to conclude that PBN reacted with the precursor radical of 8-oxodG to accelerate the formation of 8-oxodG, while OH-radical scavengers reacted with it to diminish the formation of 8-oxodG.

A survey of the values of clinical chemistry parameters obtained for a common rat blood sample in ninety-eight Japanese laboratories

A control survey was conducted to check the accuracy of automated analyzers used in the evaluation of clinical chemistry parameters in nonclinical toxicology studies. Pooled serum samples from male Sprague-Dawley rats were delivered refrigerated to each facility 98 laboratory facilities throughout Japan within 18 hours after sample preparation and analyzed. Commercially available normal human serum samples from a single lot were also analyzed at the same time. Survey results were divided into three categories. (1) Parameters with small coefficient of variation (CV) values for both rat and human serum samples included protein, glucose, cholesterol (CHO), urea nitrogen (UN), sodium (Na), potassium (K), chloride (Cl), calcium (Ca), and inorganic phosphate (IP). Definition of normal values in rats should be straight forward for these parameters. (2) Parameters with large CV values, but with a relatively good correlation between rat and human values include triglycerides (TG), glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST), glutamic pyruvic transaminase/alanine aminotransferase (GPT/ALT), and alkaline phosphatase (ALP). Measurements based on different principles gave different mean values, and this values contributed to the increase in CV values. Assessment of normal values would require a consideration of the measurement principles. (3) Parameters with large CV values only in rat serum samples included albumin (albumin/globulin ratio: A/G ratio), creatinine (CRE), and total bilirubin(BIL). Reactivity was different in rat albumin (ALB), depending on the reagents used. This difference needs to be corrected with values available by electrophoresis, or adjusted by rat ALB values, because of the lack of an appropriate measurement method. The enzyme method gave low values for rat CRE, which suggests the need for further examination of this method. The BIL values were extremely low in rat samples. It seems to be necessary to select appropriate methods to measure clinical pathology parameters correctly for rats. There was no deviation in values due solely to the mechanical operations of the analytical equipment. Non-standard initial settings of the equipment (equipment originally intended for human samples, but now applied to animal samples) was the main cause of the wide range of analytical values seen.