Synthesis, characterization, and estrogen receptor binding affinity of flavone-, indole-, and furan-estradiol conjugates

Different flavone-, indole-, and furan-17beta-estradiol conjugates, linked via alkyl spacer chains extending from the 17alpha-position of the estradiol moiety, were synthesized by Pd-catalyzed cross-coupling reactions. Structures were assigned based on spectroscopic data. In vitro competitive binding assays for the estrogen receptor (alpha-ER), using [(3)H]estradiol (RBA=100) as a competitor, revealed that a two-carbon alkyl linker combined with a flavone conjugate provided the highest binding affinity (RBA approximately 9), warranting further studies on their potential use as selective estrogen-receptor modulators (SERMs) for hormone-replacement therapies.     

Decoding an olfactory mechanism of kin recognition and inbreeding avoidance in a primate

Background  

Like other vertebrates, primates recognize their relatives, primarily to minimize inbreeding, but also to facilitate nepotism. Although associative, social learning is typically credited for discrimination of familiar kin, discrimination of unfamiliar kin remains unexplained. As sex-biased dispersal in long-lived species cannot consistently prevent encounters between unfamiliar kin, inbreeding remains a threat and mechanisms to avoid it beg explanation. Using a molecular approach that combined analyses of biochemical and microsatellite markers in 17 female and 19 male ring-tailed lemurs (Lemur catta), we describe odor-gene covariance to establish the feasibility of olfactory-mediated kin recognition.     

Forisome dispersion in Vicia faba is triggered by Ca2+ hotspots created by concerted action of diverse Ca2+ channels in sieve elements

Remote-controlled Ca²⁺ influx, elicited by electropotential waves, triggers local signaling cascades in sieve elements and companion cells along the phloem of Vicia faba plants. The stimulus strength seems to be communicated by the rate and duration of Ca²⁺ influx into sieve elements (SEs). The cooperative recruitment of Ca²⁺ channels results in a graded response of forisome culminating in full sieve-tube occlusion. Several lines of evidence are integrated into a model that links the mode and strength of the electropotential waves (EPWs) with forisome dispersion, mediated by transiently enhanced levels of local Ca²⁺ release dependent on both plasma membrane and ER Ca²⁺ channels.Key words: distant injury, electropotential wave, remote sieve tube occlusion, activity of sieve element Ca²⁺ channels, signal cascades, Ca²⁺ hotspots     

Combinatorial enzymatic assay for the screening of a new class of bacterial cell wall inhibitors

We have developed a screening assay by thin-layer chromatography (TLC) to identify inhibitors for the bacterial essential enzymes MurA, -B, and -C. Libraries of compounds were synthesized using the mix-and-split combinatorial chemistry approach. Screening of the pooled compounds using the developed assay revealed the presence of many pools active in vitro. Pools of interest were tested for antibacterial activity. Individual molecules in the active pools were synthesized and retested with the TLC assay and with bacteria. We focused on the best five compounds for further analysis. They were tested for inhibition on each of the three enzymes separately, and showed no inhibition of MurA or MurB activity but were all inhibitors of MurC enzyme. This approach yielded interesting lead compounds for the development of novel antibacterial agents.     

Observation of a possible pause mutant in the total synthesis of T4 lysozyme

A DNA of 495 bp coding for T4-lysozyme was chemically synthesized and cloned in Escherichia coli. On DNA sequence analysis, clones pTLY.10 and pTLY.9 were identified to contain identical and complete T4-lysozyme coding sequences except that pTLY.9 had an additional 23 bp inverted repeat DNA at the 3'-end of the coding sequence. On expression and purification under similar conditions, T4-lysozymes from these two clones showed different degrees of retention time on HPLC as well as in the rate of enzymatic reaction. We speculate that this difference could be due to the generation of a pause mutant of T4-lysozyme in pTLY.9 under the influence of 3'-inverted repeat DNA that alters the rate of protein synthesis.     

Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium

K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (cAMP). A transepithelial K current was induced by raising serosal [K] under short-circuit conditions. Adding Ba to the mucosal (luminal) side under these conditions had no effect; however, serosal Ba reversibly inhibited the short-circuit current (Isc), increased transepithelial resistance (Rt), and added a Lorentzian component to power density spectra of the Isc. A nonlinear relationship between corner frequency and serosal [Ba] was observed, which suggests that the rate constant for Ba association with basolateral channels increased as [Ba] was elevated. Microelectrode experiments revealed that the basolateral membrane hyperpolarized when Ba was added: this change in membrane potential could explain the nonlinearity of the 2 pi fc vs. [Ba] relationship if external Ba sensed about three-quarters of the basolateral membrane field. Conventional microelectrodes were used to determine the correspondence between transepithelially measured current noise and basolateral membrane conductance fluctuations, and ion-sensitive microelectrodes were used to measure intracellular K activity (acK). From the relationship between the net electrochemical potential for K across the basolateral membrane and the single channel current calculated from noise analysis, we estimate that the conductance of basolateral K channels is approximately 60 pS, and that there are approximately 180 million channels per square centimeter of tissue area.     

Effect of clofibrate on lipid metabolism in streptozotocin diabetic rats.

The effect of clofibrate (CPIB) on lipid metabolism was studied in male rats rendered diabetic by intravenous injection of 80 mg/kg of streptozotocin. After 1 wk, the rats received by gastric intubation 242 mg/kg/day of CPIB for 7 days. Liver lipid concentration remained unchanged in experimental diabetes and after treatment with CPIB; however, due to decreased liver weight, total liver lipids were lower in diabetic rats. Elevation of cholesterol, phospholipids, and triglycerides in the serum of diabetic rats was reversed by CPIB treatment. Hepatic cholesterol synthesis in diabetic rats was suppressed to approximately 1/10 of that in normal rats. Treatment with CPIB abolished this residual cholesterogenic activity. Diabetes had no effect on intestinal cholesterol synthesis; a slight increase was noted after CPIB treatment. Basal and norepinephrine-induced lipolysis in fat pads was elevated in diabetic rats; CPIB had no effect on these changes. The data show that the elevated serum lipids in diabetic rats are lowered by treatment with C-IB. It was concluded that the hypocholesterolemic activity of clofibrate in rats is not caused by its suppression of hepatic cholesterol synthesis.     

Stent implantation in acute myocardial infarction using a heparin-coated stent: a pilot study as a preamble to a randomized trial comparing balloon angioplasty and stenting

Preliminary experience with primary stenting in myocardial infarction has suggested a greater benefit in clinical outcome than has been obtained with direct balloon angioplasty. However, subacute thrombosis (SAT) remains a limitation for this new mode of therapy. In the BENESTENT II Pilot and main trials, the incidence of SAT with the heparin-coated Palmaz-Schatz stent was only 0.15%. Therefore, as a preamble to a large randomized trial, the feasibility and safety of the use of the Heparin-Coated Palmaz-Schatz trade mark Stent in Acute Myocardial Infarction (AMI) was tested in 101 patients enrolled between April and September 1996 in 18 clinical centres. In 101 stent-eligible AMI patients, as dictated by protocol, a heparin-coated stent was implanted. The primary objectives were to determine the in-hospital incidence of major adverse cardiac events (MACE: death, MI, target lesion revascularization) and bleeding complications, while the secondary objectives were the procedural success rate and the MACE, the restenosis and reocclusion rates at 6.5 months. Stent implantation (n 3 129 stents) was successful in 97 patients of the 101 who were included in this trial. During their hospital stay, two patients died and no patient experienced re-infarction, ischaemia prompting re-PTCA or CABG. Four patients suffered a bleeding complication, three major and one minor, of whom three required surgical repair. At 210 days follow-up, 81% of the patients were event free. At 6.5 months restenosis was documented in 18% of the 88 patients who underwent follow-up angiography, including three total occlusions. The results, both with respect to QCA and the occurrence of MACE, compare favourably with studies using elective stenting in both stable and unstable angina patients. As a result of this pilot study, a large randomized trial comparing direct balloon angioplasty with direct stenting in 900 patients with AMI was initiated in December 1996.     

Mapping and QTL analysis of horticultural traits in a narrow cross in cucumber (Cucumis sativus L.) using random-amplified polymorphic DNA markers

An 80-point genetic map [77 random-amplified polymorphic DNAs (RAPD), F (female sex expression), de (determinate), and ll (little leaf)] was constructed from a narrow cross in cucumber using the determinate, gynoecious, standard-sized leaf line G421 and the indeterminate, monoecious, little leaf line H-19. The map defined nine linkage groups and spanned ca. 600 cM with an average distance between markers of 8.4 ± 9.4 cM. The RAPD loci BC-551 and BC-592 were found to flank ll at 3.4 and 12.2 cM, respectively. The locus OP-L18-2 was linked (16 cM) to de, and the F locus was flanked by markers at 44 and 31 cM. One-hundred F3 families were used to identify quantitative trait loci (QTL) for sex expression, main stem length, number of lateral branches, days to anthesis, fruit number and weight, fruit length and diameter, and fruit length: diameter ratio in two replicated test locations (Wisconsin and Georgia). QTL on linkage group B explained major portions (R2 = ca. 2 to 74%) of the variation observed for sex expression, main stem length, lateral branch number, and fruit diameter (LOD = 2.1 to 29.8). Although ca. 62 to 74% of the variation for sex expression was associated with a putative QTL spanning the F locus (OP-AJ-2 to F and F to de), other regions (three) of the genome were important for the determination of sex in the F3 families examined depending upon environment. The number of genomic regions affecting main stem length (five) and number of lateral branches (three) coincided with expectations as determined by calculations of minimum number of genes in previous studies. Evaluation of QTL associated with several fruit number determinants of early, first-harvest yield demonstrating additive genetic variance (i.e., sex expression, main stem length, and number of laterals) suggests that marker-assisted selection may have utility for the development of determinate, multiple lateral branching germplasm suited for once-over mechanical harvesting in this population.