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.

[Subrenal capsule assay--an experimental study and clinical application to chemosensitivity tests]

We have attempted to investigate the usefulness of the subrenal capsule assay (SRCA). Initially, we compared the results of antitumor activities of 27 anticancer drugs obtained using the SRCA in BDF1 mice and the subcutaneous transplantation assay in nude mice, and it became clear that these results correlated well. It was thus apparent that the antitumor activity of drugs could be evaluated faster, more cheaply and more easily using the SRCA. In the SRCA, the overall success rate for growing tumors (with a tumor growth rate of more than 1.0) from patients was 79% (106/134) and the success rates for each tumor type were as follows: malignant lymphoma 90%, ovarian cancer 87%, sarcoma 77%, breast cancer 76%, colorectal cancer 73% and renal cancer 58%. In a retrospective analysis of correlation between the antitumor activities assayed by the SRCA and the respective clinical responses, 11 out of 25 trials were true positive (79%) and 7 trials were true negative (64%). The sensitivity and specificity levels of this test were 73% and 70%, respectively. The tumor growth inhibition rates were correlated well with the clinical responses. The advantages of the SRCA are: it has a high success rate; it allows rapid evaluation; it can be applied for masked compounds; and it has a good clinical correlation. These advantages indicate that the SRCA is of potential value as a predictive test for selection of anticancer drugs on an individual patient basis.

Autoimmune diabetes in NOD mouse is L3T4 T-lymphocyte dependent

Cultured BALB/c islets fail to function when transplanted into diabetic nonobese diabetic (NOD) mice; such grafted tissue is rapidly destroyed by disease recurrence. The cellular requirements for this graft damage are unclear. This study was designed to investigate the role of the L3T4+ T-lymphocyte subset in disease recurrence in the NOD mouse. L3T4+ T-lymphocytes were depleted by the in vivo administration of the L3T4-specific monoclonal antibody GK1.5. This treatment reduced the level of L3T4+ T-lymphocytes from an initial 43% of the peripheral blood lymphocytes to less than 4%. L3T4 levels remained at this low level for approximately 2 wk after withdrawal of GK1.5 treatment, after which the L3T4 levels slowly began to increase in the periphery. Grafting of cultured BALB/c islet tissue into GK1.5-treated diabetic NOD mice resulted in a rapid return to normoglycemia that persisted for 2-4 wk. The gradual return to the hyperglycemic condition roughly correlated with the reappearance of L3T4+ T-lymphocytes in the peripheral circulation. From these findings we conclude that the disease process in the NOD mouse is L3T4 T-lymphocyte dependent.

Interactions of metaphit with phencyclidine and sigma agonist actions in rat cerebellum: determination of specificity and selectivity

The interactions of phencyclidine (PCP) and related agonists with putative receptor blockers were studied on cerebellar Purkinje neurons using electrophysiological techniques. Depressions induced by PCP or dexoxadrol, a sigma receptor agonist, were markedly antagonized by the PCP receptor antagonist metaphit, which acylates PCP receptors via its isothiocyanate moiety. Conversely, the depressant effect of levoxadrol, the (-) isomer of dexoxadrol, was not affected by metaphit. Further evidence that metaphit's specific antagonism of dexoxadrol- and PCP-mediated depressions was derived from data showing that drugs which respectively acylate mu and delta opioid receptors, benzimidazole isothiocyanate and fentanyl isothiocyanate, do not antagonize the actions of either PCP or dexoxadrol. Moreover, tyramine, which like PCP acts as an indirect norepinephrine agonist, is not antagonized by metaphit. These observations support the concept that metaphit causes a pharmacologically specific and irreversible antagonism of the effects of both PCP and dexoxadrol in the cerebellum. Thus, the electrophysiological mechanisms of PCP actions are similar to those triggered by sigma opioid agonists in this brain area.

Detection of oncogene mRNA sequences in cultured cells by in situ hybridization

The present study was undertaken to determine the feasibility of using in situ hybridization techniques to identify oncogene transcription in cultured cells. Following in situ hybridization with 32P-labeled v-src and v-Ha-ras DNA probes, src and Ha-ras related transcripts were identified in cell lines transfected with v-src and Ha-ras, respectively. In both the v-src and c-Ha-ras transfected cell lines, the number of silver grains over individual cells were significantly higher (p less than 0.001, t-test) than in a non-transfected, non-tumorigenic, rat esophageal epithelial cell line. There was a highly variable number of silver grains above individual cells. Significantly fewer silver grains were counted over cells that had been preincubated with either non-labeled v-src or v-Ha-ras DNA or that were pretreated with RNase A. Both oncogene transfected cell lines contained approximately 10 times more oncogene related mRNAs than non-transfected cells as judged by the numbers of silver grains over individual cells. Filter-hybridization analysis of the transfected and non-transfected cell lines confirmed that the expression of src and Ha-ras transcripts was higher in the transfected cell lines than in the non-transfected cell line. Therefore, the in situ hybridization technique would appear useful for the identification of oncogene transcripts in single cells and could potentially be applied to cytological preparations of human cells and to human tumor cells in culture.

pUC12-W1: a plasmid vector for the study of cloned DNA conformation

pUC12-W1 is a new cloning vector for the study of torsion-induced structural transitions of insert DNA. It was derived from pUC12 by deleting three A + T-rich sequences which can undergo structural transitions when torsionally stressed. Transitions at these sites have low energy of activation and undefined structures. They complicate studies on transitions of DNA inserts by diverting torsional force and causing the vector to be undefined in helical and energetic terms. The new vector pUC12-W1, from which these segments have been deleted, will facilitate studies of torsion-induced structural transitions of insert DNA.

[Flow cytometer (FCM) in biological characteristics of nasopharyngeal carcinoma xenografts in nude mice]

Tumor tissue from a patient with nasopharyngeal carcinoma was transplanted to nude mice (BALB/c) and had successfully been maintained through ten passages. The nude mice tumor and the primary human tumor were assayed by FCM for the DNA content in addition to conventional pathological examination, chromosome analysis and EBV assay. The tumor incidence in the different passages showed a marked change ranging from 25% to 81% with a mean value of 52% which tended to increase, however. The doubling time of six tumors in the ninth passage showed no great change 6-12 weeks after transplantation with a mean about 4.3 days. But at week 12, there was a significant difference between each tumor volume, ranging from 438 to 1,998 mm3. By FCM, it was found that the DNA index remained constant in both the primary and nude mice tumors. Among the nude mice tumors in different passages, the distribution of various phase cells in cell cycle was similar to that of the primary tumor. In conclusion, the use of FCM to assay the cellular DNA content in nude mice tumor is rapid and sensitive. It is helpful, for the nude mice tumor, in identifying stability of the biological characteristics and in studying of the mechanism of chemotherapy and radiotherapy in the future.