Sequence dependent conformations of oligomeric DNA's in aqueous solutions and in crystals

In order to determine the sequence dependence of the conformation of deoxynucleotides, Raman spectra have been obtained for the following oligodeoxynucleotides in aqueous salt solutions and in crystals: d(CpG)(I), d(TGCGCGCA)(II), d(CACGCGTG)(III), d(CGTGCACG)(IV), d(CGCATGCG)(V), d(ACGCGCGT)(VI), d(CGCGTACGCG)(VII), d(CGCACGTGCG)(VIII) and d(CGTGCGCACG)(IX), d(GCTATAGC) (X), d(GCATATGC) (XI), d(GGTATACC) (XII) and d(GGATATCC) (XIII). The normal B type conformation is observed for all the oligomer DNA's at low salt (0.1-1.0 M NaCl) concentration in the temperature range of 0-25 degrees C. It was considered possible that all of the first nine oligomers could go into the Z form in aqueous high salt (5.0-6.0 M NaCl) solutions, and under these conditions the last four were considered candidates to go into the A form. The B-type conformation was found to exist in high salt solutions for (I), (IV), (V), (VI), (X), (XI) and (XIII); the Z or partial Z conformation appears in high salt solution for the oligomers, (II), (III), (VII), (VIII) and (IX); an A or partial A conformation appears in high salt solution for (XII). In the crystalline state, (IV), (VIII), (X), and (XI) stay in the B-form and all of the other oligomers adopt the complete Z-form except for (XII) which crystallizes in the A form. In both the crystal and in aqueous solutions, the identification of the conformation genus was made by means of Raman spectroscopy. In the crystal of (I), grown at pH7.0, guanosine is found to be in C3'-endo/syn conformation and cytidine in C2'-endo/anti, which may be taken as the ideal building block of the typical Z conformation. At pH4, (I) crystallizes in a conformation similar to the B genus. A study of the thermally induced B to Z transition has been carried out for (II) and (III). Based on the analysis of Raman spectra of the alternating pyrimidine-purine oligomers which might be expected to go into the Z form, the tendency for these oligonucleotides to adopt the Z form can be ranked as: d(CGCGCGCG) greater than (II) greater than (III) greater than (V) approximately (VI) greater than (IV) for octamers and (VII) greater than (VIII) greater than (IX) for the decamers. Similarly, those oligomers which might have a tendency to go into the A form could be ranked as (XII) greater than (XIII) approximately (X) greater than (XI). These data should provide help in formulating rules for predicting the sequence dependence of the B to A and B to Z transitions. Some possible rules are explored, but precautions should be taken.

Clinical application of laser Doppler flowmetry for measurement of cutaneous circulation in health and disease

The cutaneous laser Doppler device (LDF) was employed to determine its usefulness in differentiating the circulation of the feet in normal subjects from that in patients with arteriosclerosis obliterans. It is shown that the laser Doppler frequencies correlated well with results from venous occlusion plethysmography, which measured volume rate of flow. Thus, one can determine volume rate of flow by the simple Doppler method. There was a linear relationship between these two methods of measurements. Using the LDF method, it was determined that normal individuals have toe flows that on the average are 42% of finger flows in supine resting subjects. In peripheral vascular disease of the lower extremities, the LDF measurements showed a decreased circulation in the large toes when the patients are supine and the lower extremities flat. The results between health and disease are exaggerated by elevating the feet, at which time the diseased circulation falls to extremely low values compared with those of normal subjects. A similar decrease in skin oxygen tension in the diseased lower extremities was observed when the limbs were elevated.

A tissue-specific transcriptional enhancer is found in the body of the HLA-DR alpha gene

We mapped cis-acting regulatory elements in the HLA-DR alpha gene, which encodes the monomorphic subunit of the HLA-DR heterodimer. Genomic fragments of HLA-DR alpha were placed 5' or 3' to the chloramphenicol acetyltransferase reporter gene, the transcription of which was initiated from the Herpes simplex thymidine kinase promoter. In transient expression assays, fragments from the body of the HLA-DR alpha gene were able to increase chloramphenicol acetyltransferase activity in a position-, orientation-, and promoter-independent yet tissue-specific fashion. These HLA-DR alpha cis-acting regulatory elements contain previously identified DNase I-hypersensitive sites and DNA sequences homologous to those found in other eukaryotic transcriptional enhancers.

Mapping structurally perturbed sites in DNA by replication arrest and run-off replication

We describe a technique for rapid fine mapping of sites of torsion-induced perturbations of DNA structure. The technique involves strand scission or chemical base modification at structurally perturbed sites, replication arrest in a double-strand DNA sequencing reaction, and size analysis of replication products by electrophoresis on sequencing gels. Besides being less complicated and faster than site identification by conventional end-labeling methods, the technique assures high sequence specificity through the use of oligomeric sequencing primers. This property should be useful for in vivo mapping of DNA structural perturbations with known sequence within complex genomes.

Sequence dependence of the B to Z transition in crystals and aqueous NaCl solutions for deoxyoligonucleotides containing all four canonical DNA bases

A laser Raman study has been made on the conformation of a series of self-complementary octameric deoxynucleotides that contain all four canonical deoxynucleotide bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] in order to determine which sequences will crystallize in the Z form and which sequences will go into the Z form in aqueous solution at high salt concentrations (4-6 M NaCl). All four octadeoxynucleotides, d(TGCGCGCA) (I), d(CACGCGTG) (II), d(CGTGCACG) (III), and d(CGCATGCG) (IV), have been crystallized from low-salt solutions. The Raman spectra of microcrystals show that I, II, and IV crystallize in a rigorous Z form while III crystallizes in the B form. Sequences I and II go into a Z form in 4-6 M NaCl solution at 0 degrees C while sequences III and IV remain in the B form in 6 M salt. There are substantial differences in the Raman spectra of oligonucleotides in the Z form found in the crystal and in high-salt solutions. The Raman spectra of the Z forms in 6 M NaCl solution at 0 degrees C are not linear combinations of the Raman spectra of the complete Z form in the crystal and the complete B form in low-salt solutions. The terminal residues of these oligomers do not appear to be in a strict Z form. A detailed analysis of the ring puckers and syn/anti conformation for all of the residues both in solution and in the crystal has been made.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of insulin mediators in regulation of cAMP and lipogenesis as well as in diabetes

Plasma membranes prepared from pig, mouse and rat liver incubated with insulin resulted in the release of at least two insulin chemical mediators. These mediators, identified as fractions 1 and 3, were found to inhibit cAMP level in response to lipolytic hormone and forskolin and to enhance lipogenesis in adipocytes of rat. Fractions 1 and 3 have been estimated to have molecular weights of 3700-4000 and 1000-1500 dalton, respectively. This initial report will focus on fraction 1. Interestingly, liver membranes from diabetic animals were found not to release mediators in the presence of insulin. However, following in vivo treatment of diabetic animals with insulin, the liver membranes appeared to restore its ability in generating chemical mediators in response to insulin.

[Analysis of clinical responses in comparison with the results of the chemosensitivity test by subrenal capsule assay]

We attempted to examine the practicality and the usefulness of 6-day subrenal capsule assay (SRCA) as a predictive chemosensitivity test. The success rate of this assay was 81% in 150 cases of various cancers. The drug sensitivity was evaluated by the inhibition rate of tumor growth (TGIR) on day 6 after drug treatment without immunosuppression of mice. We analyzed the clinical response in comparison with the results of SRCA in 38 cases in which transplanted tumor showed over 1.0 tumor growth rate (TGR). The average TGIR in these cases attained CR, PR, MR, NC and PD clinically were 60, 60, 49, 53 and 40%, respectively. The TGIR of CR and PR cases were significantly greater than that of PD cases (p less than 0.05). These results in SRCA correspond to clinically observed responses, using a greater than or equal to 45% inhibition in TGIR to define 'sensitivity'. Of 26 patients sensitive in SRCA, 18 patients (69%) showed true positive and 75% of patients (12 cases) resistant in the assay also failed to respond clinically (true negative). In the cases with less than 1.0 in TGR, a correlation between clinical responses and TGIR was not found. Based on these results, 6-day SRCA without immunosuppresive procedures can be utilized as a predictive chemosensitivity test for cancers which can grow over 1.0 in TGR in this assay system.

Infrared and Raman studies show that poly(dA).poly(dT) and d(AAAAATTTTT)2 exhibit a heteronomous conformation in films at 75% relative humidity and a B-type conformation at high humidities and in solution

The decadeoxynucleotide d(AAAAATTTTT)2 in duplex form and the double-helical polynucleotide poly(dA).poly(dT) have been studied by Raman and infrared (IR) spectroscopy under a variety of environmental conditions. The IR spectra have been taken of cast films and compared to the IR spectra of the alternating poly(dA-dT), which shows clear B-genus and A-genus vibrational spectra under conditions of high (greater than 92%) and low (75%) relative humidity (RH). From the IR data, it is shown that d-(AAAAATTTTT)2 and poly(dA).poly(dT) adopt a B-genus conformation in films with high water content. When the relative humidity of the film is decreased, the IR spectra reflect a gradual evolution of the geometry of both d(AAAAATTTTT)2 and poly(dA).poly(dT) into a form intermediate between the B genus and A genus, but the IR spectrum of a pure A genus has not been obtained. In these DNAs at 75% RH, the IR bands of adenosine have the same frequencies as those found in poly(dA-dT) at 75% RH where the local furanose conformation is C3' endo/anti, but the thymidine frequencies do not resemble those of poly(dA-dT) at 75% RH but rather those of poly(dA-dT) at high humidities. It is concluded that both poly(dA).poly(dT) and d(AAAAATTTTT)2 adopt a fully heteronomous duplex geometry in cast films at low humidity. For studies in aqueous solution the Raman effect was employed. As a model for the heteronomous conformation in solution, the duplex poly(rA).poly(dT) was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Prazosin-induced alterations in renal alpha-adrenergic receptor function

Chronic (3-day) treatment with prazosin causes an increase in renal alpha 2-adrenergic receptor density and the relocation of renal tubular alpha 2-adrenergic receptors from extrajunctional to postjunctional sites. We investigated whether chronic prazosin treatment (2 mg/kg, i.p.) caused a functional alteration of other renal alpha 2-adrenergic receptors, using the isolated perfused rat kidney. Prazosin significantly reduced blood pressure and increased heart rate during the 3-day treatment. Renal nerve stimulation (2-8 Hz, 10 V, 1 msec) caused a frequency-dependent increase in renovascular resistance, which was potently blocked by prazosin in vitro in both control and prazosin-treated rat kidneys. The vasoconstrictor response to the alpha 2-adrenergic receptor-selective agonist BHT 933 (3-300 microM) was significantly higher in kidneys from prazosin-treated rats. Yohimbine (3-300 nM) potentiated the response to renal nerve stimulation in both treatment groups. The increase in vascular resistance following renal nerve stimulation was lower in kidneys from prazosin-treated rats, but the response to the alpha 1-adrenergic receptor agonist methoxamine (0.3-1 microM) was unchanged. Further studies revealed that renal nerve stimulation-evoked norepinephrine release from prazosin-treated rat kidneys was significantly lower than release from untreated controls. This response could be normalized to control levels by a combination of cocaine (10 microM) and yohimbine (100 nM). Thus, chronic prazosin treatment caused enhanced alpha 2-adrenergic receptor-mediated vasoconstriction and facilitated renal prejunctional inhibitory mechanisms. We conclude that with chronic alpha 1 adrenergic receptor blockade there is increased alpha 2-adrenergic receptor function in at least two and possibly three sites in the kidney; these include postjunctional tubular, prejunctional vascular, and possibly extra-junctional vascular sites.

Enhanced antitumor activity of 5'-deoxy-5-fluorouridine against Lewis lung carcinoma in aged hybrid (C57BL/6 x DBA/2) F1 mice

The antitumor activity of 5'-deoxy-5-fluorouridine (5'-DFUR) against Lewis lung carcinoma was examined by implanting the tumor subcutaneously into young (8-11 weeks) and old (24-41 weeks) hybrid (C57BL/6 x DBA/2)F1 (BDF1) male mice. Oral administration of 5'-DFUR induced a small (7 of 100) but significant (p less than 0.05) number of 70-d survivors in young mice. However, the antitumor activity was further enhanced in the old mice, and 15 of 46 (32.6%) and 11 of 62 (17.7%) mice survived for 70-d by treatment with 2000 and 1000 mg 5'-DFUR/kg/d, respectively, given on days 1, 5, and 9. The reason for the higher cure rate in old mice was partly analyzed. Toxicity of 5'-DFUR in young and old mice did not differ significantly, regardless of the presence (except 2000 mg/kg) or absence of Lewis lung carcinoma. No survivors were observed after treatment with 5'-DFUR when the tumors were implanted into the aged (15-38 weeks) syngeneic hosts, C57BL/6 mice. On the other hand, the survival time of BDF1 mice implanted with a constant number of the tumor cells increased significantly with the increase in host age and reached a maximum at the age of 24 weeks. These findings suggest that an optimal activation of 5'-DFUR (to 5-FU) was carried out in the old BDF1 mice bearing Lewis lung carcinoma and/or that a host-mediated antitumor mechanism of BDF1 mice, which is reinforced with aging, might participate in the enhancement of the antitumor activity of 5'-DFUR against this tumor.

The reaction mechanism of N-benzoylimidazole with ribonucleotides

The reaction of uridine 3'-phosphate with benzoylimidazole in the absence and presence of a strong base was followed up by 31P and 1H nmr as well as paper electrophoresis. Possible reaction courses were proposed, the reaction rate constants were calculated and the reaction mechanism was discussed. It is possible to selectively acylate ribonucleotides with benzoylimidazole by appropriate choice of the base used.

[Preclinical evaluation of a new camptothecin derivative, CPT-11, on the subrenal capsule assay]

CPT-11 is a new derivative of camptothecin, a plant alkaloid developed in Japan. We investigated the antitumor activity of CPT-11 on the subrenal capsule assay by using 39 tumor samples from patients with various tumors. The overall chemosensitivity rate of CPT-11 was 44% and the mean tumor growth inhibition rate was 44% in all the tumors. In 18 ovarian cancer cases, the chemosensitivity rate was 56% and the mean tumor growth inhibition rate was 46%. The antitumor activity obtained by CPT-11 is comparable to that of adriamycin, cyclophosphamide and 5-fluorouracil in the same assay system. Based upon these results, CPT-11 is considered to be a good candidate for clinical trials.