A case of spontaneous coronary artery disease regression

Coronary angiographic trials have demonstrated that lowering cholesterol can slow the progression of atherosclerosis, limit the formation of new lesions and enhance atherosclerotic regression together with reducing the incidence of clinical events (Waters D, 1996). Spontaneous regression of coronary atherosclerotic lesions is rare. We report the case of a patient with a severe within-stent restenotic lesion whose coronary disease spontaneously regressed 12 months after initial diagnosis, allowing for medical treatment of symptoms rather than repeated intervention. (Int J Cardiovasc Interventions 1999; 2: 121-123)     

New dye-labeled terminators for improved DNA sequencing patterns.

We have used two new dye sets for automated dye-labeled terminator DNA sequencing. One set consists of four, 4,7-dichlororhodamine dyes (d-rhodamines). The second set consists of energy-transfer dyes that use the 5-carboxy-d-rhodamine dyes as acceptor dyes and the 5- or 6-carboxy isomers of 4'-aminomethylfluorescein as the donor dye. Both dye sets utilize a new linker between the dye and the nucleotide, and both provide more even peak heights in terminator sequencing than the dye-terminators consisting of unsubstituted rhodamine dyes. The unsubstituted rhodamine terminators produced electropherograms in which weak G peaks are observed after A peaks and occasionally C peaks. The number of weak G peaks has been reduced or eliminated with the new dye terminators. The general improvement in peak evenness improves accuracy for the automated base-calling software. The improved signal-to-noise ratio of the energy-transfer dye-labeled terminators combined with more even peak heights results in successful sequencing of high molecular weight DNA templates such as bacterial artificial chromosome DNA.     

Single adult rabbit and rat cardiac myocytes retain the Ca2+- and species-dependent systolic and diastolic contractile properties of intact muscle

The systolic and diastolic properties of single myocytes and intact papillary muscles isolated from hearts of adult rats and rabbits were examined at 37 degrees C over a range of stimulation frequencies and bathing [Ca2+]o (Cao). In both rabbit myocytes and intact muscles bathed in 1 mM Cao, increasing the frequency of stimulation from 6 to 120 min-1 resulted in a positive staircase of twitch performance. During stimulation at 2 min-1, twitch performance also increased with increases in Cao up to 20 mM. In the absence of stimulation, both rabbit myocytes and muscles were completely quiescent in less than 15 mM Cao. Further increases in Cao caused the appearance of spontaneous asynchronous contractile waves in myocytes and in intact muscles caused scattered light intensity fluctuations (SLIF), which were previously demonstrated to be caused by Ca2+-dependent spontaneous contractile waves. In contrast to rabbit preparations, intact rat papillary muscles exhibited SLIF in 1.0 mM Cao. Two populations of rat myocytes were observed in 1 mM Cao: approximately 85% of unstimulated cells exhibited low-frequency (3-4 min-1) spontaneous contractile waves, whereas 15%, during a 1-min observation period, were quiescent. In a given Cao, the contractile wave frequency in myocytes and SLIF in intact muscles were constant for long periods of time. In both intact rat muscles and myocytes with spontaneous waves, in 1 mM Cao, increasing the frequency of stimulation from 6 to 120 min-1 resulted, on the average, in a 65% reduction in steady state twitch amplitude. Of the rat myocytes that did not manifest waves, some had a positive, some had a flat, and some had a negative staircase; the average steady state twitch amplitude of these cells during stimulation at 120 min-1 was 30% greater than that at 6 min-1. In contrast to rabbit preparations, twitch performance during stimulation at 2 min-1 saturated at 1.5 mM Cao in both intact rat muscles and in the myocytes with spontaneous waves. We conclude that the widely divergent, Ca2+-dependent systolic and diastolic properties of intact rat and rabbit cardiac muscle are retained with a high degree of fidelity in the majority of viable single myocytes isolated from the myocardium of these species, and that these myocytes are thus a valid model for studies of Ca2+-dependent excitation-contraction mechanisms in the heart.     

Factors influencing the release of proteins by cultured schwann cells

Cultured rat schwann cells grown in association with sensory neurons when labeled with [(3)H]leucinem, [(3)H]glucosamine, or [(35)S]methionine release labeled polypeptides into the culture medium. Analysis by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of the culture medium reveals a reproducible pattern of more than 20 polypeptides with molecular weights ranging from 15,000 to more than 250,000. Five major polypeptides (apparent molecular weights 225,000, 210,000, 90,000, 66,000, 50,000, and 40,000) account for approximately 40 percent of the leucine or methionine radioactivity in medium polypeptide. Schwann cells grown in a serum-free defined medium, in which schwann cells do not relate normally to axons, release approximately four times less labeled medium polypeptides tha cultures grown in medium supplemented with serum and chick embryo extract. In addition, there is a qualitative difference in the pattern of medium polypeptides resolved by SDS-PAGE, so that a single polypeptide (mol wt 40,000) accounts for nearly all of the label in medium polypeptides. Switching of cultures grown in defined medium to supplemented medium for 2 d results in a fourfold increase in the amount of labeled polypeptides appearing in the culture medium, and a return to the normal pattern of medium polypeptides appearing in the culture medium, and a return to the normal pattern of medium polypeptides as resolved by SDS-PAGE. This change in the pattern of polypeptides release by schwann cells is accompanied by changes in the association between schwann cells and axons. An early step in the establishment of normal axon-schwann cell relations appears to be an inward migration of schwann cells into axonal bundles and spreading of schwann cells along neurites. These changes are evident within 48 h after medium shift. Our results thus suggest that the release of proteins by schwann cells may be important for the development of normal axonal ensheathment.     

The relationship between codon boundaries and multiple reading-frame preferences: coding organization of bacterial insertion sequences

Theoretical considerations have shown that the five possible overlapping reading-frame configurations differ significantly in their coding flexibility and thus in their information content (Siegel and Fitch 1980; Smith and Waterman 1980). Contrary to expectation, the overlapping frame configuration allowing the greatest coding flexibility is rarely seen, whereas one of the most constraining is common. We point out here that this overlapping reading-frame paradox and an observed but unexplained preference in coding regions for a pyrimidine-purine at codon boundaries (Shepherd 1981; Jones and Kafatos 1982; Smith et al. 1983) are intimately linked. The codon boundary preference, which may be related to translation efficiency or accuracy, places constraints on the evolution of overlapping coding regions. These considerations may help identify actual coding regions in DNA sequences. We have analyzed five sequenced (enteric) bacterial insertion sequences for codon boundary incidences and reading-frame configurations and find that they are consistent with these proposed constraints.      

Inhibition of aminoacyl-transfer ribonucleic acid synthetases and the regulation of amino acid biosynthetic enzymes in Neurospora crassa.

Growth conditions that result in the accumulation of the tryptophan intermediate indoleglycerol phosphate or of the histidine intermediate imidazoleglycerol phosphate cause mycelia of Neurospora crassa to exhibit an immediate and sustained increase in the differential rate at which the biosynthetic enzymes of the tryptophan, histidine, and arginine pathways are synthesized. These accumulated intermediates are shown to be inhibitors of the activity of aminoacyltransfer ribonucleic acid (tRNA) synthetases, as judged by an in vitro esterification assay. The tryptophan intermediate is shown to inhibit the charging of tryptophan, and the histidine intermediate is shown to inhibit charging of histidine. The inhibitions noted are consistent with the finding that the level of charged tRNATrp is decreased significantly in cells that have accumulated indoleglycerol phosphate and that of tRNAHis is decreased significantly in cells that have accumulated imidazoleglycerol phosphate. These results are interpreted as support for the involvement of aminoacyl-tRNA species in mediating cross-pathway regulation of the tryptophan, histidine, and arginine biosynthetic pathways as proposed in Lester's polyrepressor hypothesis (G. Lester, 1971). the correlations noted lead to the conclusion that Neurospora utilizes regulatory mechanisms that have the ability to react to changes in the level of charging of tRNA species.     

Studies on the actin-binding protein HS1 in platelets

Background  

The platelet cytoskeleton mediates the dramatic change in platelet morphology that takes place upon activation and stabilizes thrombus formation. The Arp2/3 complex plays a vital role in these processes, providing the protrusive force for lamellipodia formation. The Arp2/3 complex is highly regulated by a number of actin-binding proteins including the haematopoietic-specific protein HS1 and its homologue cortactin. The present study investigates the role of HS1 in platelets using HS1^-/- mice.     

<i>Trichoderma</i> spp. fostering growth on <i>Capsicum chinense</i> Jacq. seedlings and antagonistic against <i>Meloidogyne incognita</i>

Fourteen native strains of Trichoderma spp. from wildand agricultural pathosystems in the state of Yucatan, Mexico, with growth-promoting ability of Capsicum chinense Jacq. seedlings were evaluated and antagonistic effect of their filtrate against second-stage juveniles (J2) of Meloidogyne incognita. The strains Th05-02 and Th27-08 showed the best significant effects on plant hight variable increments 55.57 and 47.62%, theTh07-04 with 29.48% more root length, theTh02-01 and Th07-04 isolates increased from 48.71 to 84.61% in volume radical and 53.40% of total dry biomass. Statistical analysis (p≤0.001) of Th43 and Th43-13-14 filtrates caused 100% mortality at 24 and 48h. In the test of reversibility to 24 h after replacing the filtrates Th43-13, Th43-14, TH09-06 and TH20-07 by sterile distilled water, the J2 did not recover their viability, so they were considered as the best potential strains of Trichoderma spp. with antagonistic capacity in J2 of M.incognita.     

High-level expression of the 32.5-kilodalton calelectrin in ductal epithelia as revealed by immunocytochemistry

Abstract. Calelectrins are a family of antigenically related Ca²⁺-binding proteins that have only recently been described. They have the important property of binding to membranes only in the presence of Ca²⁺. We systematically studied the tissue localization of one calelectrin, the 32.5-kilodalton species, in rats using immunocytochemistry. We found that high levels were exclusively present in the epithelial cells of bile and pancreatic ducts, renal collecting ducts, bronchial epithelia, and brain ependyma. In all of these organs, the other cells were not immunoreactive. In addition, strong immunoreactivity was found in the intercalated disks of myocardial cells, and mild immunoreactivity was observed in several endocrine tissues. In contrast, the cellular distribution of the 67-kilodalton calelectrin was more diffuse, involving most parenchymal cells in addition to the already-mentioned cells. Due to the presence of high levels of 32.5-kilodalton calelectrin in some cell types, this protein may be used as a histochemical marker for differentiated ductal epithelial cells, some specialized epithelia, myocardial cells, and Paneth cells.