Search

A cascoded GaN half-bridge with a wide-band galvanically isolated current sensor is proposed. A 650 V depletion-mode GaN field-effect transistor is switched by a low-propagation-delay gate driver in active-mode. The standby and active modes are switched by a 25 V N-ch laterally diffused MOS (LDMOS). The current sensor uses the LDMOS as a shunt resistor, gm-cell-based sense amplifier and a mixer-based isolation amplifier for wider bandwidth. PVT variations of on-resistance of the current-detecting MOSFET are compensated using a reference MOSFET. A digital calibration loop across the isolation is formed to keep the current sensor gain constant within ± 1.5 % across the whole temperature range. The wide-band current sensor can measure the power device switching current. In this study, a cascoded GaN half-bridge switching and inductor current sensing using low-side and high-side device current are demonstrated. The proposed techniques show the possibility of implementing a GaN half-bridge module with an isolated current sensor in a package.

[structure: see text] Eight new compounds, MPC1001 and MPC1001B-H, were isolated from the fungus Cladorrhinum sp. KY4922. Multiple NMR experiments and CD data revealed MPC1001 to be an O-methyl derivative of emestrin, a 15-membered antifungal antibiotic containing a unique epidithiodioxopiperazine skeleton. Other compounds were elucidated to be structurally related novel analogues. MPC1001 and the analogues exerted potent antiproliferative activities against a human tumor cell line.

Three new macrolides, micromonospolides A–C, have been isolated from a new species of the genus Micromonospora and their structures were elucidated to be bafilomycin-type macrolides which have a 16-membered lactone ring on the basis of spectroscopic data. Micromonospolides A–C inhibited gastrulation of starfish embryos at minimum inhibitory concentrations of 0.010, 0.011 and 1.6 μg mL−1, respectively.

The structures of two novel non-peptidic endothelin type B receptor antagonists, RES-1149-1 and -2 were determined by spectroscopic methods. Several derivatives were synthesized from RES-1149-1 for biological assay.

RES-701-1, a novel cyclic peptide endothelin antagonist, was isolated from the culture broth of Streptomyces sp. RE-701. RES-701-1 selectively inhibited the ET-1 binding to type B endothelin receptor (ETB receptor) with an IC50 of 10 nM expressed in CHO cells and blocked the ET-1-induced elevation of intracellular free Ca2+ concentration in ETB receptor-expressing COS-7 cells. Characterization of producing strain, fermentation, isolation, structure, physico-chemical and biological properties of RES-701-1 are described.

A new macrolide, micromonospolide A, was isolated from an undescribed actinomycete, Micromonospora sp., and its structure was elucidated to be a bafilomycin-type macrolide which has a 16-membered lactone ring on the basis of spectroscopic data. Micromonospolide A inhibited gastrulation of starfish embryos at a concentration of 10 ng/ml or greater.

Seven novel potent antitumor antibiotics, duocarmycins A (1), C1 (2), C2 (3), D (4), B1 (5), B2 (6) and SA (7), were isolated from three independently collected Streptomyces sp. The complete structures, including absolute stereochemistry, were determined by spectral and chemical studies of those duocarmycins and several derivatives. Duocarmycins A (1) and SA (7) possess a 1,2,7,7a-tetrahydrocycloprop[1,2-c]indol-4-one subunit, a common pharmacophore with that of CC-1065 (10) found from Streptomyces zelensis.

RES-1214-1 and -2, novel and non-peptidic endothelin antagonists, were isolated from the cultured broth of a fungus, Pestalotiopsis sp. RE-1214. RES-1214-1 and -2 selectivity inhibited the ET-1 binding to endothelin type A receptor (ETA receptor) with IC50 values of 1.5 microM and 10 microM, respectively. RES-1214-1 and -2 inhibited the increase in intracellular Ca2+ concentration elicited by 1 nM ET-1 in A10 cells. Taxonomy of producing strains, fermentation, isolation, structural determination, and biochemical properties of RES-1214-1 and-2 are described.

Three new macrolides, micromonospolides A–C, have been isolated from a new species of the genus Micromonospora and their structures were elucidated to be bafilomycin-type macrolides which have a 16-membered lactone ring on the basis of spectroscopic data. Micromonospolides A–C inhibited gastrulation of starfish embryos at minimum inhibitory concentrations of 0.010, 0.011 and 1.6 μg mL−1, respectively.

A new macrolide, micromonospolide A, was isolated from an undescribed actinomycete, Micromonospora sp., and its structure was elucidated to be a bafilomycin-type macrolide which has a 16-membered lactone ring on the basis of spectroscopic data. Micromonospolide A inhibited gastrulation of starfish embryos at a concentration of 10 ng/ml or greater.

The anticellular and antitumor activities of novel antitumor antibiotics, duocarmycins (DUMs), were examined against human and murine tumor cells. DUMs consist of live compounds, A, B1, B2, C1, and C2, which possess a pharmacophore similar to that of CC‐1065, a previously isolated antibiotic. Among them, DUMA exhibited ultrapotent growth‐inhibitory activity with an IC50 value of 6 pM against human uterine cervix carcinoma HeLa S3 cells. DUMA and DUMB1 also inhibited the growth of adriamycin (ADM)‐resistant lines of human nasopharynx carcinoma KB cells and breast carcinoma MCF‐7 cells as well as their sensitive lines. DUMs inhibited the growth of s.c.‐inoculated murine tumors such as B16 melanoma, sarcoma 180, M5076 sarcoma and colon 26. DUMs were also significantly effective in increasing the lifespan of i.p.‐inoculated B16 melanoma‐bearing mice, although their effect was marginal against other i.p.‐inoculated tumors. As a whole, DUMB1 exhibited superior activity to the other four compounds. DUMB1 rapidly inhibited the incorporation of [3H]‐TdR into macromolecules of HeLa S3 cells as compared with that of [3H]UR or [3H]leucine. DNA strand breaks were detected in DUMB1 ‐treated HeLa S3 cells by agarose gel electrophoresis with a contour‐clamped homogeneous electric field apparatus. These results indicate that DUMs possess interesting biological activities as DNA‐targeting antitumor antibiotics.

Six duocarmycins have been discovered during our search for new antitumor antibiotics and they showed extremely potent cytotoxic activity with IC50 values of 10(-12) M-10(-9) M on HeLa S3 cell. Three different producing strains isolated from soils were taxonomically assigned as Streptomyces. Duocarmycin A was unstable in culture broth, so improved culture conditions were designed to produce a high titer of duocarmycins B1, B2, C1 and C2 which are halogenated seco-compounds of duocarmycin A. Duocarmycin SA, one of the most potent cytotoxic agents yet discovered, was shown to be more stable in culture media than duocarmycin A, despite the structural similarity on their spirocyclopropylhexadienone moiety. In contrast to the duocarmycin A fermentation, no halogenated seco-compounds of duocarmycin SA were detected in culture broth supplemented with Br- or Cl-. All duocarmycins could be produced using one producing strain with improved media and culture conditions.

The IkappaB kinase (IKK)-related kinase NAK (also known as TBK or T2K) contributes to the activation of NF-kappaB-dependent gene expression. Here we identify NAP1 (for NAK-associated protein 1), a protein that interacts with NAK and its relative IKK epsilon (also known as IKKi). NAP1 activates NAK and facilitates its oligomerization. Interestingly, the NAK-NAP1 complex itself effectively phosphorylated serine 536 of the p65/RelA subunit of NF-kappaB, and this activity was stimulated by tumor necrosis factor alpha (TNF-alpha). Overexpression of NAP1 specifically enhanced cytokine induction of an NF-kappaB-dependent, but not an AP-1-dependent, reporter. Depletion of NAP1 reduced NF-kappaB-dependent reporter gene expression and sensitized cells to TNF-alpha-induced apoptosis. These results define NAP1 as an activator of IKK-related kinases and suggest that the NAK-NAP1 complex may protect cells from TNF-alpha-induced apoptosis by promoting NF-kappaB activation.

Profound vasodilation of the kidneys and other nonreproductive organs transpires during early pregnancy. Because nitric oxide (NO) was found to mediate renal vasodilation and hyperfiltration in conscious pregnant rats, and endogenous endothelin (ET) was suggested to be vasodilatory in the renal circulation of nonpregnant rats, we tested whether endothelin mediates the NO-dependent changes in the renal circulation during pregnancy. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in conscious pregnant and virgin rats before and during infusion of 30 μg/min RES-701-1 (a selective ETBreceptor subtype antagonist). Baseline GFR and ERPF were significantly increased by 35% in gravid rats relative to virgin controls. During infusion of RES-701-1, the pregnant rats responded more robustly, showing a greater decline in both GFR and ERPF such that renal function converged in the two groups of rats. ERPF also converged in pregnant and virgin rats during infusion of SB-209760, a nonselective ETA/Breceptor subtype antagonist. Combined infusion of Nω-nitro-l-arginine methyl ester [l-NAME, an NO synthase (NOS) inhibitor] and RES-701-1 reduced GFR and ERPF to levels comparable to those reached with either agent given alone, suggesting inhibition of a common vasodilatory pathway. RES-701-1 and SB-209670 significantly lowered the cGMP content of small renal arteries from gravid and virgin rats in vitro, strengthening the link between the renal endothelial ETBreceptor subtype and NO. Importantly, we showed that RES-701-1 is not a direct inhibitor of NOS. We conclude that endothelin mediates the NO-dependent changes in the renal circulation of conscious rats during pregnancy.

RES-1149-1 and -2, produced by Aspergillus sp. RE-1149, were found to be non-peptidic antagonists for endothelin type B receptor (ET(B) receptor). RES-1149-1 and -2 selectively inhibited the endothelin-1 (ET-1) binding to ET(B) receptor in a competitive manner with IC50 values of 1.5 microM and 20 microM, respectively. RES-1149-1 inhibited the increase in intracellular Ca2+ concentration elicited by 1 nM ET-1 in COS-7 cells expressing human ET(B) receptor, but not in the case of cells expressing ET(A) receptor. In addition, some structure-activity relationships are described.

RES-1149-1 and -2, novel and non-peptidic endothelin antagonists, were isolated from the cultured broth of a fungus, Aspergillus sp. RE-1149. RES-1149-1 and -2 selectively inhibited the ET-1 binding to endothelin type B receptor (ETB receptor) with IC50 values of 1.5 microM and 20 microM, respectively. Taxonomy of producing strains, fermentation, isolation, and physico-chemical properties of RES-1149-1 and -2 are described.

RES-1214-1 and -2, novel and non-peptidic endothelin antagonists, were isolated from the cultured broth of a fungus, Pestalotiopsis sp. RE-1214. RES-1214-1 and -2 selectivity inhibited the ET-1 binding to endothelin type A receptor (ETA receptor) with IC50 values of 1.5 microM and 10 microM, respectively. RES-1214-1 and -2 inhibited the increase in intracellular Ca2+ concentration elicited by 1 nM ET-1 in A10 cells. Taxonomy of producing strains, fermentation, isolation, structural determination, and biochemical properties of RES-1214-1 and-2 are described.

RES-701-2, -3 and -4, novel cyclic peptide endothelin antagonists, were isolated from the culture broths of Streptomyces sp. RE-701 and RE-896, RES-701s selectively inhibited the ET-1 binding to endothelin type B receptor (ETB receptor) with IC50 values ranging from 5 to 20 nM. Taxonomy of the producing strains, fermentation, isolation and biochemical properties of RES-701s are described.

Seven novel potent antitumor antibiotics, duocarmycins A (1), C1 (2), C2 (3), D (4), B1 (5), B2 (6) and SA (7), were isolated from three independently collected Streptomyces sp. The complete structures, including absolute stereochemistry, were determined by spectral and chemical studies of those duocarmycins and several derivatives. Duocarmycins A (1) and SA (7) possess a 1,2,7,7a-tetrahydrocycloprop[1,2-c]indol-4-one subunit, a common pharmacophore with that of CC-1065 (10) found from Streptomyces zelensis.

Various polyamine analogs were examined for their ability to stimulate and to function as sparing agents for the Mg2+ requirement in polypeptide synthesis at various temperatures in Escherichia coli (37 and 47 degrees C) and the extremely thermophilic Thermus thermophilus (60 and 70 degrees C) cell-free systems. The optimal concentration of each polyamine analog increased as the incubation temperature was elevated. At a fixed temperature, the optimal concentration of polyamine analogs was in the order diamines greater than triamines greater than tetraamines greater than pentaamines. All diamines tested stimulated polypeptide synthesis almost equally but lowered the optimal Mg2+ concentration in the order diaminopropane greater than putrescine greater than cadaverine. The degree of diamine stimulation was maximal at 37 degrees C. The effects of three triamines were very similar in the E. coli system but in the T. thermophilus system spermidine was most effective in stimulation of polypeptide synthesis. From the results of experiments using tetraamines and pentaamines, it was deduced that the presence of both aminobutyl and aminopropyl groups in polyamine analogs is important for stimulation of polypeptide synthesis. In the E. coli system, triamines were the most effective polyamines for stimulation of polyphenylalanine synthesis at both 37 and 47 degrees C, while, in the T. thermophilus system, thermospermine, a tetraamine, was most effective at 60 degrees C and 3,4,4,3-pentaamine was most effective at 70 degrees C.

In this paper, the production from streptomyces, the isolation, the physico-chemical properties and biological activity of duocarmycins B 1 and B 2 are reported

Prostaglandin F2alpha (PG F2alpha) was administered to pregnant women at a dosage of 50 microng or 100 microng by extraovular route around the expected time of childbirth in order to induce labor. (1) PG F2alpha 50 microng or 100 microng dissolved in 10 ml of physiological saline solution was infused by extraovular administration through the cervical canal of the uterus with the use of Nelaton catheter No. 9. The catheter was then immediately withdrawn and the patient allowed to return home. (2) Instilation of 10ml of physiological saline solution was carried out for control purposes. (3) Those who reported labor contractions within 24 hours after the infusion were regarded as cases of excellent response, and those who reported labor contractions more than 24 hours after the infusion, or those who showed dilatation and improvement in effacement of the uterine cervical canal though without the occurrence of labor contractions were deemed to be cases of good response. The overall positive response rate (excellent plus good) was 78.9% for primiparae and 85.7% for multiparae in the group receiving 50 microng and 89.5% for primiparae and 100% for multiparae in the group receiving 100 microng. (4) Labor contraction were induced at a rate of almost 100% in those who showed dilatation of the cervical canal of the uterus to the extent of 3 cm or more and effacement to the extent of 50% or more. (5) It is advisable to perform reinfusion of PG F2alpha or instilation of PG F2alpha as a post-treatment in patients with good responses. (6) The infusion of PG F2alpha is effective for the induction of labor in older primiparae, cases of breech presentation and suspected cases of CPD. (7) There were some cases of enhanced response when PG F2alpha was given as posttreatment.