The effect of isradipine administration on existing fatty streaks in the cholesterol-fed rabbit: a morphometric study

Previous studies have shown that the administration of certain calcium channel blocking drugs (at an appropriate time point) can reduce the severity of atherosclerotic lesion formation. This study was undertaken to determine if the administration of isradipine would reverse established lesions produced by feeding rabbits an atherogenic diet. Rabbits were fed cholesterol for three weeks and examined directly, or after being left for a four week washout period, with or without a daily oral supplement of isradipine. Fatty streaks were well established after three weeks of cholesterol feeding and were more extensive at the end of the washout period, as indicated by gross changes in the volume of the intima per unit length of aorta. When isradipine was administered during the washout period, the volume of the intima per unit length of aorta fell to levels below those produced by cholesterol feeding for three weeks alone. The major components of the lesions affected to accommodate these changes were the foam cells and myointimal cells; these were examined in detail using morphometry and lipid cytochemistry. The mean volume of intima/cm of aorta occupied by foam cells and myointimal cells both fell by more than 60% to levels lower than those found after three weeks of cholesterol feeding alone. The volume of the extracellular space of the intima occupied by cytochemically demonstrable unesterified and esterified cholesterol was reduced by isradipine administration as was that of foam cells, all to levels lower than those found after three weeks of cholesterol feeding alone. These data indicate that the administration of isradipine during a washout period, after cholesterol feeding, can promote the regression of fatty streak lesions.     

Interaction of nonylphenol and hepatic CYP1A in rats

Both estradiol and nonylphenol (NP) inhibited hepatic microsomal 7-ethoxyresorufin O-deethylase (EROD) activity of beta-naphthoflavone-treated rats. Enzyme kinetic analyses (Lineweaver-Burk plots) using different estradiol and NP concentrations with graded increases in the concentrations of the substrate, ethoxyresorufin, showed that the inhibition was of a competitive nature at all concentrations of estradiol or NP used. Thus, the mechanism by which NP inhibits EROD activity is similar to that of estradiol. NP, however, was much less potent than estradiol. Young rats treated in vivo with 80 mg/kg body weight of NP demonstrated a slight but significant decrease in their hepatic microsomal EROD activity and CYP1A protein as measured by western blot analysis. In addition, treatment with NP led to a decrease in the steady-state levels of hepatic CYP1A mRNA in rats, suggesting that NP acted at the pre-translational level. The competitive nature of inhibition by NP on hepatic microsomal EROD activity indirectly suggests that this compound is a possible substrate of the CYP1A enzyme. Furthermore, NP had a moderate modulating effect on the expression of CYP1A in rat liver.     

Detection of M. leprae by gene amplification; combined ethidium-bromide staining and probe hybridization

Human and animal studies have clearly demonstrated the advantageous effects of sensorially enriched rearing environments. Nevertheless, little work has been done concerning the long-lasting persistence of all these behavioral modifications. To undertake this question, a very early enrichment animal model was used. From days 10 to 24 after birth, 28 male albino rats were exposed to a multisensory stimulated environment, while other 28 littermates constituted the control group. At 3 and 6 months old two cognitive abilities were analyzed; the spatial working memory (short term memory) and the latent learning capacity (long term memory). The results evidenced an improved working memory in both 3 and 6 months old rats exposed to the early enriched environment. Moreover, the adult early stimulated group performed as well as younger subjects both on error scores and speed to solve this test. Only in the adult group of rats a superior latent learning capacity of stimulated subjects was evidenced. To conclude, the early enriched environment induced: a) persistent cognitive benefits in the adult rat and b) a more relevant influence on the subsequent behavior of older rather than younger subjects.     

Comparison of the genomic short regions of a vaccine strain (SA-2) and a virulent strain (CSW-1) of infectious laryngotracheitis virus (Gallid herpesvirus 1)

Restriction enzyme linkage maps were produced for the genomic short region of the virulent infectious laryngotracheitis virus (CSW-1 strain). After comparison with the equivalent restriction enzyme linkage maps for the infectious laryngotracheitis virus SA-2 strain (a vaccine strain), it was determined that the maps for the short regions of the two strains were identical, apart from a single section in each of the inverted terminal repeats. Each inverted terminal repeat of the SA-2 strain was discovered to contain 467 base pairs more DNA than the CSW-1 strain's inverted terminal repeats. This extra DNA was more precisely mapped entirely within the EcoRI fragments D and d of SA-2, which were found to form part of the SmaI fragments U and P of SA-2 and Q and b of SA-2 and to contain one SmaI restriction enzyme site.     

Dimension and related anatomical distance of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia

INTRODUCTION: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. METHODS AND RESULTS: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His-bundle area and the base of the coronary sinus orifice (DHis-OS) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His-bundle recording site from the successful ablation site (DHis-Ab) and the distance as a fraction of the entire length of Koch's triangle (DHis-Ab/DHis-Os) were determined. The mean DHis-Os and DHis-Ab were 25.9 +/- 7.9 and 13.4 +/- 3.8 mm, respectively. DHis-Os negatively correlated with patient age (r = -0.41, P < 0.0001) and body mass index (r = -0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, DHis-Os was longer (27.2 +/- 6.6 vs 24.6 +/- 8.4 mm, P < 0.005), DHis-Ab was similar (12.9 +/- 3.1 vs 13.9 +/- 4.0, P > 0.05) and DHis-Ab/DHis-Os was smaller (0.48 +/- 0.04 vs 0.74 +/- 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 +/- 4 vs 4 +/- 3, P < 0.05). CONCLUSION: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His-bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle; therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter DHis-Os to avoid injury to AV node.     

Population-specific screening by mutation analysis for diseases frequent in Ashkenazi Jews

Three-dimensional (3D) imaging of intracellular rhodamine 123 fluorescence distribution was performed by means of confocal laser scanning microscopy (CLSM). Human IGR melanoma cells grown in monolayer or multicellular spheroid culture were studied for elucidating mitochondrial membrane potential characteristics, and cell and nucleus volume dimensions. Microspheres 6 microns in diameter loaded with rhodamine B were used to calibrate our instruments for performing 3D imaging of optical sections as obtained by CLSM. Accurate optical slicing is only possible taking into consideration the physical characteristics of the objectives used like chromatic and spherical aberrations, depth discrimination or cover slip correction and the temperature dependence of the immersion medium. While 3D imaging of optical slices can be carried out showing the original shape of the object being tested without physical distortion, 3D images of microspheres show well-reproducible structures of rhodamine B fluorescence. These can be explained by a superposition of two effects, namely scattering of the fluorescence light and a gradient of the electromagnetic field strength of the laser beam due to the shape of the object. 3D imaging of optical slices of IGR cells in monolayer or multicellular spheroid culture, which have been loaded with rhodamine 123, show the location of the dye predominantly within the cytoplasm of the cells with a remarkable heterogeneity of fluorescence intensity within and between single cells, indicating differences in the mitochondrial membrane potential and thus in the metabolic activity. Due to the heterogeneity of the cell shape the cell nucleus occupies between 4 and 14% of the total cell volume. These data reveal calibrated 3D imaging as a valuable noninvasive tool to visualize the heterogeneity of cell parameters under different cell culture conditions.     

Multiple members of the leucokinin neuropeptide family are present in cerebral and abdominal neurohemal organs in the cockroach Leucophaea maderae

Two neurohemal organs of the cockroach Leucophaea maderae, the corpora cardiaca and the lateral heart nerve are known to contain leucokinin immunoreactive material. We examined the corpora cardiaca and the lateral heart nerve to establish whether these neurohemal organs store all 8 known leucokinin isoforms or if the leucokinins have a differential distribution. Extracts of corpora cardiaca and abdominal hearts with attached lateral heart nerve were separated on reversed phase high performance liquid chromatography (rpHPLC), then tested for leucokinin immunoreactivity by a radioimmunoassay (RIA) able to detect all 8 leucokinin isoforms. Extracts from brain and optic lobes were also separated and assayed in the RIA. Synthetic leucokinin 1-8 were subjected to rpHPLC and their different retention times established by RIA for reference. Leucokinin immunoreactive material originating from the corpora cardiaca and lateral heart nerves eluted in fractions corresponding to those of the synthetic leucokinin 1-8. In this study we have thus demonstrated that probably all 8 leucokinin isoforms are stored in the corpora cardiaca and the lateral heart nerve. These observations suggest that all 8 leucokinins are likely to be released as neurohormones into the circulation.     

Impact of cholesterol reduction on peripheral arterial disease in the Program on the Surgical Control of the Hyperlipidemias (POSCH)

BACKGROUND: Few lipid/atherosclerosis intervention trials have assessed the impact of cholesterol reduction on peripheral arterial disease. The 838 patients evaluated in the Program on the Surgical Control of the Hyperlipidemias (POSCH) trial represent more than the total number of patients in the seven previously reported studies. METHODS: Peripheral arterial disease in POSCH was assessed by progression of clinical disease, serial changes in the systolic blood pressure ankle/brachial index (ABI), and changes on sequential peripheral arteriograms. RESULTS: At the time of formal closure of the POSCH trial on July 19, 1990, claudication or limb-threatening ischemia was exhibited in 72 of 417 control group (CG) patients and in 54 of 421 intervention group (IG) patients (IG relative risk [RR] 0.702, 95% confidence interval [CI] 0.169 to 1.000, p = 0.049). With additional follow-up evaluation to September 30, 1994, clinical peripheral arterial disease was evident in 91 CG patients and 64 IG patients (RR 0.656, 95% CI 0.200 to 0.903, p = 0.009). At the 5-year follow-up evaluation, an ABI of less than 0.95 was present in 41 of 120 CG patients and in 24 of 126 IG patients, all of whom had an ABI of 0.95 or greater at baseline (RR in the IG of 0.557, 95% CI 0.360 to 0.863, p < 0.01). No appreciable differences were noted in the progression or regression of arteriographic peripheral arterial disease between the two groups. CONCLUSIONS: Effective cholesterol reduction in POSCH led to statistically significant differences between the control and the intervention groups in the development of clinically evident peripheral arterial disease and in the ABI values, but not in the peripheral arteriograms. Additional studies need to assess the correlation between peripheral arterial changes and coronary arterial changes and clinical atherosclerosis events. Intervention trials that study peripheral arterial disease have intrinsic value in the evaluation of the impact of risk factor modification on progression of atherosclerotic peripheral arterial disease.     

A new enzyme superfamily - the phosphopantetheinyl transferases

BACKGROUND: All polyketide synthases, fatty acid synthases, and non-ribosomal peptide synthetases require posttranslational modification of their constituent acyl carrier protein domain(s) to become catalytically active. The inactive apoproteins are converted to their active holo-forms by posttranslational transfer of the 4'-phosphopantetheinyl (P-pant) moiety of coenzyme A to the sidechain hydroxyl of a conserved serine residue in each acyl carrier protein domain. The first P-pant transferase to be cloned and characterized was the recently reported Escherichia coli enzyme ACPS, responsible for apo to holo conversion of fatty acid synthase. Surprisingly, initial searches of sequence databases did not reveal any proteins with significant peptide sequence similarity with ACPS. RESULTS: Through refinement of sequence alignments that indicated low level similarity with the ACPS peptide sequence, we identified two consensus motifs shared among several potential ACPS homologs. This has led to the identification of a large family of proteins having 12-22 % similarity with ACPS, which are putative P-pant transferases. Three of these proteins, E. coli EntD and o195, and B. subtilis Sfp, have been overproduced, purified and found to have P-pant transferase activity, confirming that the observed low level of sequence homology correctly predicted catalytic function. Three P-pant transferases are now known to be present in E. coli (ACPS, EntD and o195); ACPS and EntD are specific for the activation of fatty acid synthase and enterobactin synthetase, respectively. The apo-protein substrate for o195 has not yet been identified. Sfp is responsible for the activation of the surfactin synthetase. CONCLUSIONS: The specificity of ACPS and EntD for distinct P-pant-requiring enzymes suggests that each P-pant-requiring synthase has its own partner enzyme responsible for apo to holo activation of its acyl carrier domains. This is the first direct evidence that in organisms containing multiple P-pant-requiring pathways, each pathway has its own posttranslational modifying activity.