Processing of mutated proinsulin with tetrabasic cleavage sites to bioactive insulin in the non-endocrine cell line, COS-7

The amino acid sequence, Arg-4-X-3-Lys/Arg-2-Arg-1 decreases X+1, is thought to be a consensus processing site for a constitutive secretory pathway in non-endocrine cells. We created a mutant proinsulin DNA with a peptide structure of B chain-Arg-Arg-Lys-Arg-C peptide-Arg-Arg-Lys-Arg-A chain, which compares to the native proinsulin structure of B chain-Arg-Arg-C peptide-Lys-Arg-A chain. When the mutant insulin was expressed in a monkey kidney-derived cell line, COS-7, approximately 60% of the total immunoreactive insulin appeared as mature insulin in the culture medium. This conversion to the mature form was strikingly facilitated by co-expressing the mutant proinsulin with furin, a homologue of the yeast endoprotease, Kex2.

Selective inhibitory effects of calcium channel antagonists on the two components of the neurogenic response of guinea pig vas deferens

The effects of L-type calcium channel antagonists and omega-conotoxin on the contractile responses of guinea pig vas deferens were examined in vitro. Electrical stimulation of the postganglionic hypogastric nerve induced biphasic contraction consisting of rapid phasic and delayed tonic components. L-type calcium channel antagonists, such as diltiazem, verapamil and nicardipine, mainly inhibited the delayed tonic component, whereas omega-conotoxin mainly inhibited the rapid phasic component. Stimulations in the presence of prazosin and alpha, beta-methylene ATP induced rapid transient and delayed contraction, respectively, which were inhibited by omega-conotoxin and L-type calcium channel antagonists, respectively. Short-term stimulation with five pulses induced a small fast phasic contraction. This contraction, which could be desensitized by alpha, beta-methylene ATP, was inhibited by omega-conotoxin, but not by L-type calcium channel antagonists. At the concentrations used in the present study, none of the calcium channel antagonists inhibited the contractions induced by exogenously added ATP or norepinephrine. These findings suggest that L-type calcium channel antagonists and omega-conotoxin inhibit the neurotransmissions mediated by norepinephrine and ATP, respectively, from the postganglionic nerve to the vas deferens of the guinea pig. Inhibition of the voltage-dependent calcium channel is discussed in relation to the mechanism of cotransmission in this preparation.

Photochemically obtained N-demethyl derivatives of anthracyclines

New N-monodemethyl and N-didemethyl derivatives were obtained from seven N-dimethylamino sugar (rhodosamine)-containing anthracyclines by photochemical reaction and their in vitro bioactivities against L1210 cell culture were compared with those of their N-dimethyl parent compounds. N-Demethyl derivatives obtained from betaclamycin T (7-O-rhodosaminyl-beta-rhodomycinone) were much more cytotoxic while those from the other six antibiotics were rather less active as compared with their parent compounds. The N-demethylation also gave a considerably greater decrease in the inhibitory activity on RNA synthesis as compared to DNA synthesis, so that the N-demethyl derivatives showed smaller IC50 ratios on DNA/RNA than their parent compounds.

Papaverine inhibits transcytotic vesicle transport and lipid excretion into bile in isolated perfused rat liver

Papaverine is a nonspecific smooth muscle relaxant and a phosphodiesterase inhibitor. Its effects on biliary excretion of lipids and horseradish peroxidase were investigated in a single-pass isolated perfused rat liver model. A constant infusion of papaverine (1.6 mumol/min; 40 mumol/L) significantly increased bile flow (microliters per minute per gram of liver) before (2.03 +/- 0.09 vs. 1.0 +/- 0.06) and after sodium taurocholate infusion (2.77 +/- 0.10 vs. 1.88 +/- 0.11). However, papaverine significantly and reversibly reduced biliary excretion of phospholipids and cholesterol (nanomoles per minute per gram of liver) after a 1.0 mumol/min sodium taurocholate infusion, from 7.45 +/- 0.83 and 1.42 +/- 0.15 to 1.75 +/- 0.18 and 0.39 +/- 0.06, respectively (p less than 0.01), whereas secretion of bile acids was unaffected. When a 1-min pulse of horseradish peroxidase (25 mg) was infused in isolated perfused rat liver after a continuous infusion of N6,O-2'-dibutyryladenosine 3',5'-cyclic monophosphate (0.25 mumol/min; 6.25 mumol/L), horseradish peroxidase appeared in bile in an early (4 to 6 min) and late (20 to 25 min) peak. Papaverine significantly reduced the late peak, from 1.211 +/- 0.264 to 0.498 +/- 0.107 (p less than 0.01). Papaverine had no significant effects on either cyclic AMP or cyclic GMP in the liver and bile, although it has been reported that papaverine is a phosphodiesterase inhibitor. These findings indicate that papaverine inhibits biliary excretion of lipids but not bile acids, and they suggest that papaverine has an inhibitory effect on transcytotic vesicle transport independent of an increase of cyclic nucleotides in hepatocytes.

Syntheses and activities of N-substituted derivatives of siastatin B

N-Substituted derivatives of siastatin B have been obtained by a chemical modification. Some derivatives showed potent inhibitory activities against Streptococcus sp. and Clostridium perfringens neuraminidases.

Isolation and characterization of a chicken tyrosinase cDNA

Complementary DNA clones coding for chicken tyrosinase were isolated from retinal pigmented epithelium of chicken embryo. Sequence analysis shows that one of the cDNA clones consisting of 1,997 nucleotides has an open reading frame coding for 529 amino acids. The deduced protein has nine N-glycosylation sites and a transmembrane region. A sequence comparison of the deduced chicken tyrosinase with the mouse and human homologues revealed that amino acid sequences are conserved for the entire polypeptides. Seventy-two percent and 73% of amino acids in the chicken sequence are identical to that of the mouse and human tyrosinases, respectively. Histidines neighboring the postulated copper-binding sites and the cysteines are well conserved. RNA blotting analysis showed that a major transcript of 2.5 kb is detected in retinal pigmented epithelium of a 9-day-old chicken embryo.

Elevated interleukin-6 and gamma-globulin during interferon therapy of hepatitis B

A 49-yr-old man with chronic hepatitis B manifested hypergammaglobulinemia, lymphadenopathy, and a high serum interleukin-6 level following treatment with recombinant human alpha-interferon. One month later, when the patient was treated with natural beta-interferon, serum levels of interleukin-6 and gamma-globulin increased again. The serum gamma-globulin decreased to the pretreatment level after discontinuation of interferon therapy. The serum alanine aminotransferase level remained normal for 6 months. In this case, hypergammaglobulinemia and lymphadenopathy, as well as the elevated serum interleukin-6 level, were considered to be signs of highly enhanced humoral immunity related to alpha- and beta-interferon therapy.

Visual evoked potentials in guinea pigs with brain lesion

Visual evoked potentials (VEPs) were recorded in 10 adult male guinea pigs with brain lesion. Lesions were produced in 5 animals by superficial suction of the occipital lobe. The other 5 animals were orally administered with hexachlorophene (about 35 mg/kg/day) for 28 days. In the VEP following the ablation of the occipital lobe, the peaks P10, N20, P55, N75, N140 and P200 disappeared in many cases. The amplitude of the peak N40 decreased to approximately one half its control VEP. In the VEP obtained from the animals administered with hexachlorophene, the peak latencies of N20, P30, P55, N75 and P100 were slightly prolonged after the 7th day following the first administration. On the other hand, there was no change in the latency of N40 during the whole period of administration. The peak-to-peak amplitude showed some variability in different peaks. Histologically, diffuse status spongiosis were found in the white matter of the cerebrum, cerebellum, and brain stem. As described above, the ablation of the occipital lobe caused markedly depressed VEPs, however, the responses to the photic stimulation persisted after the injury. On the other hand, the VEPs of animals administered with hexachlorophene showed a high probability of peak appearance, and a decrease in amplitude was not marked.

Amino acid analogs of benanomicin A through desalaninebenanomicin A

Desalaninebenanomicin A has been synthesized in good yield by the cleavage of the amido bond of benanomicin A using MEERWEIN's reagent. This is a useful intermediate to prepare amino acid analogs of benanomicin A. MEERWEIN's reagent reacts with totally protected benanomicin A to give a stable imino ether. After deprotection, the imino ether is treated with aqueous acetone at reflux to afford a methyl ester of desalaninebenanomicin A. Desalaninebenanomicin A was coupled with a variety of amino acids by the active ester method to afford new benanomicin analogs.

Cyclooctatin, a new inhibitor of lysophospholipase, produced by Streptomyces melanosporofaciens MI614-43F2. Taxonomy, production, isolation, physico-chemical properties and biological activities

Cyclooctatin has been isolated from Streptomyces melanosporofaciens MI614-43F2 as part of a program designed to find microorganism-produced inhibitors of lysophospholipase. It was purified by chromatography on silica gel, Capcell Pak C18 (HPLC) and Sephadex LH-20 followed by solvent extraction and then isolated as a colorless powder. Cyclooctatin has the molecular formula of C20H34O3. It is competitive with the substrate, and the inhibition constant (Ki) was 4.8 x 10(-6) M.

Action site of the lethal Ay gene in the mouse embryo

We investigated the lethal effect of Ay gene in embryos at the preimplantation stage in vitro. First, the development until the blastocyst stage and the division of individual cells from 8-cell stage embryos were examined. No difference in development was detected between embryos from the experimental cross (Ay/a x Ay/a) and those from the control cross (a/a x a/a). Therefore, it seems that the abnormality of the Ay/Ay embryo does not appear until blastocyst formation in vitro. We subsequently examined the hatching from zona pellucida of the blastocysts. The hatching ratio of the embryos from the experimental cross was significantly lower than that of the control crosses (Ay/a x a/a, a/a x a/a: p < 0.05). Our observation indicates that deficiency of the Ay/Ay embryo can be detected in vitro at hatching. In order to elucidate the mechanism of the gene action of the Ay, we attempted to rescue the lethal embryos from decreased hatching ratio in vitro. When dbcAMP at the concentration of 1 mM was added to the culture medium, the hatching ratio of blastocysts from the experimental cross increased until the level of those from the control crosses. Since this result indicates that the cAMP content in Ay homozygote seemed to be lower than those in a/a and Ay/a, the cAMP content in individual blastocyst was quantified. It is found that Ay homozygosity was associated with lower level of cAMP. When adenylate cyclase was activated by forskolin and cholera toxin, the hatching ratio was increased. These results seem to suggest that Ay homozygote embryos possess a defect in signal transduction system mediated by adenylate cyclase during hatching.

Production of new anthracycline antibiotics 1-hydroxy-oxaunomycin and 6-deoxyoxaunomycin by limited biosynthetic conversion using a daunorubicin-negative mutant

A limited biosynthetic conversion of some known anthracyclinones using a specific daunorubicin-nonproducing mutant provided four new anthracycline antibiotics: 1-Hydroxy-10-methoxycarbonyl-13-deoxocarminomycin; 1-hydroxy-13-deoxocarminomycin; 1-hydroxyoxaunomycin and 6-deoxyoxaunomycin. Their isolation and purification from bioconversion broth, structural determination and antitumor activities against leukemic L1210 cells are described.

Chemosensitivity testing of clinical gastrointestinal cancers using histoculture and the MTT end-point

Three-dimensional histoculture with the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) end-point was utilized for chemosensitivity testing of 100 clinical gastrointestinal cancers and the results were compared with those obtained with cell-suspension culture with the MTT end-point. Of the 100 surgical specimens, 91 were evaluable using histoculture assay and 66 were evaluable using the cell-suspension assay. When the assay results were compared with historical frequency of clinical response to chemotherapy, the results of the histoculture assay showed a closer correlation than those of the cell-suspension assay. Therefore, the histoculture assay seems to have a higher evaluability rate and a closer correlation with clinical chemosensitivity of gastrointestinal cancers than the cell-suspension assay.

Analysis of a unique molecule responsible for regeneration and stabilization of differentiated state of tissue cells

In Wolffian regeneration in the newt, a functional lens can be regenerated through cellular transdifferentiation of the pigmented epithelium of the mid-dorsal marginal iris. A novel monoclonal antibody, 2NI-36 mAb, generated in our laboratory has been utilized as a highly useful probe to study newt lens regeneration. The antigen molecule against this 2NI-36 mAb (2NI-36) became temporarily undetectable only at the site of lens regeneration. Moreover, the ventral iris pieces expressed the ability to differentiate a lens when pretreated with this monoclonal antibody and implanted in lentectomized eyes (Eguchi, Cell Differ. Dev. 25, Suppl., 1988). We have investigated the distribution of 2NI-36 in newt tissues. 2NI-36 was not specific to iris pigmented epithelium and distributed in many different kinds of mesodermal tissues, including dermis, blood vessel, mesonephros and so forth. 2NI-36 was also detected in either cell surface or intercellular spaces of cultured pigmented epithelial cells when they organized an epithelial cell sheet. Western blot analysis showed that 2NI-36 had the molecular weight of 50-200kD and was completely digested by trypsin, suggesting that 2NI-36 was a glycoprotein with many carbohydrate chains. It was also revealed by Western blot analysis that all the tissues in which 2NI-36 could be detected expressed this molecule similar to that in the iris epithelium. We expect that 2NI-36 is a glycoprotein expressed by various newt tissues and is functional to stabilize the differentiated state of each tissue cell in the same way as observed in the iris pigmented epithelial cells.

Benastatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12. II. Structure determination of benastatins A and B

Benastatins A and B, new inhibitors of glutathione S-transferase, have been isolated from the culture broth of Streptomyces sp. MI384-DF12. By X-ray crystallography, benastatin A was determined to be 8,13-dihydro-1,7,9,11-tetrahydroxy-13-dimethyl-8-oxo-3-pentyl- benzo[a]naphthacene-2-carboxylic acid. The structure of benastatin B was elucidated by NMR studies.

Nagstatin, a new inhibitor of N-acetyl-beta-D-glucosaminidase, produced by Streptomyces amakusaensis MG846-fF3. Taxonomy, production, isolation, physico-chemical properties and biological activities

Nagstatin, a new inhibitor of N-acetyl-beta-D-glucosaminidase (NAG-ase) was discovered in the fermentation broth of Streptomyces amakusaensis MG846-fF3. It was purified by chromatography on Dowex 50W, Avicel and Sephadex LH-20 followed by the treatment of active carbon and then isolated as colorless powder. Nagstatin has the molecular formula of C12H17N3O6. It is competitive with the substrate, and the inhibition constant (Ki) was 1.7 x 10(-8) M.

Non-Alzheimer non-Pick dementia with Fahr's syndrome

Five patients with non-Alzheimer non-Pick dementia combined with Fahr's syndrome were studied. Atypical clinical pictures emerged from an evaluation of these cases. Their symptoms and signs could be attributed neither to Alzheimer's disease nor to Pick's disease but to a partial mixture of both. The neuropathological changes were characteristic, and the common findings were as follows: 1) the absence of senile (neuritic) plaques, 2) the widespread presence of numerous neurofibrillary tangles throughout the neocortex, 3) a calcareous deposition of Fahr's type, 4) a circumscribed cerebral atrophy in the temporal or/and frontal lobes, 5) a moderate or severe demyelination and fibrous gliosis in the white matter of the atrophied areas and 6) a mild or moderate neuronal loss in the nucleus basalis of Meynert. These neuropathological changes were not due to Alzheimer's disease nor to Pick's disease. Similar cases reported previously were reviewed.

Benastatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12. I. Taxonomy, production, isolation, physico-chemical properties and biological activities

Benastatins have been isolated as part of a program designed to find microorganism-produced inhibitors of glutathione S-transferase from Streptomyces sp. MI384-DF12. They were purified by chromatography of reversed-phase silica gel, silica gel and Capcell Pak C18 (HPLC) followed by solvent extraction and then isolated as yellow powders. Benastatins A and B have the molecular formulae, C30H28O7 and C30H30O7, respectively. They were competitive with 3,4-dichloronitrobenzene as the substrate, and the inhibition constants (Ki) of benastatins A and B were 5.0 x 10(-6) and 3.7 x 10(-6), respectively.

Anthracycline metabolites from baumycin-producing Streptomyces sp. D788. I. Isolation of antibiotic-blocked mutants and their characterization

Biosynthetically blocked mutants were obtained from a baumycin-producing Streptomyces sp. D788 newly isolated from soil. The first mutant isolated was a baumycin-negative but daunorubicin-accumulating mutant with a loss of 4'-substitution activity, from which all other blocked mutants were successively derived. These included a known 11-deoxydaunorubicin-producing mutant and several new types of mutants which produced mainly 10-carboxy-13-deoxocarminomycin, 10-methoxycarbonyl-13-deoxocarminomycin, their 11-deoxy derivatives or a precursor aglycone, respectively. In this paper, all the anthracycline components produced by the parent strain and its two known blocked mutants, a daunorubicin producer and a 11-deoxydaunorubicin producer, are also determined by HPLC and five new components are isolated. Cytotoxicities in vitro of all the components against L1210 cell culture are also described.

A new model of plastic ankle foot orthosis (FAFO (II)) against spastic foot and genu recurvatum

A plastic ankle foot orthosis (AFO) was developed, referred to as functional ankle foot orthosis Type 2 (FAFO (II)), which can deal with genu recurvatum and the severe spastic foot in walking. Clinical trials were successful for all varus and drop feet, and for most cases of genu recurvatum. Electromyogram studies showed that the FAFO (II) reduced the spasticity of gastrocnemius and hamstring muscles and activated the quadricep muscles. Gait analysis revealed a reduction of the knee angles in the stance phase on the affected side when using the FAFO (II). Mechanical stress tests showed excellent durability of the orthosis and demonstrated its effectiveness for controlling spasticity in comparison with other types of plastic AFOs.