Search

This study evaluated the incremental prognostic value of 201TI reinjection imaging over clinical, exercise and thallium stress-redistribution data in patients with previous myocardial infarction and left ventricular dysfunction. METHODS: Thallium-201 reinjection after stress-redistribution SPECT was performed in 104 consecutive patients with a first Q-wave myocardial infarction (> 8 wk) and left ventricular ejection fraction < or = 40%. Follow-up data (mean 22 mo) were available for 98 patients; 16 patients underwent early revascularization procedures within 3 mo after exercise testing and were not considered for the analysis. RESULTS: During follow-up there were 13 hard events (cardiac death and myocardial infarction) and 11 soft events (coronary revascularization procedures > 3 mo after thallium imaging). With multivariate Cox regression analysis, the sum of defects at stress-redistribution imaging that were reversible or moderate irreversible after reinjection was a powerful predictor of subsequent events. The addition of thallium reinjection imaging data significantly improved the prognostic power of clinical, exercise and stress-redistribution data for the occurrence of hard events (p < 0.01). CONCLUSION: In patients with previous myocardial infarction and left ventricular dysfunction, thallium reinjection imaging provides incremental prognostic information over those obtained from conventional stress-redistribution imaging.

Autonomic dysfunction has been reported in patients with hypertrophic cardiomyopathy. To evaluate the influence of different clinical and echocardiographic features of the disease on sympathovagal balance, as assessed by heart rate variability, 33 patients with hypertrophic cardiomyopathy and 33 healthy volunteers underwent echocardiographic examination and 24-hour electrocardiogram Holter recording. Measures of vagal modulation of heart rate were lower in patients with hypertrophic cardiomyopathy than in controls, particularly in those exhibiting syncope, exertional chest pain, dyspnea, or moderate or severe mitral regurgitation. Furthermore, the age-corrected multiple regression analysis showed that the parasympathetic cardiac control was inversely related to left atrial dimension and directly related to left ventricular end-systolic dimension. Therefore in hypertrophic cardiomyopathy the parasympathetic withdrawal is more evident in patients with symptoms than in those without; the reduction in left ventricular end-systolic dimension and the increase in left atrial size are the echocardiographic features that most influence the sympathovagal balance.

Objective: This double-blind, placebo-controled randomized study was designed to compare the antihypertensive effect and tolerability of extended-release felodipine and slow-release nifedipine retard in elderly hypertensive patients. Methods: Thirty patients of both sexes (mean age 71 years) with mild to moderate essential hypertension were recruited from our hypertension outpatient clinic. After a 2-week placebo period, felodipine extended-release (felodipine ER), 10 mg once daily, nifedipine slow-release retard (nifedipine SR), 20 mg twice daily or placebo were administered to each patient for 2 weeks according to a 3 × 3 latin-square design. At the end of each treatment period, the patients underwent 24-h noninvasive blood pressure monitoring. Results: All of the patients completed the trial and no serious adverse experience was reported. In comparison with placebo, felodipine and nifedipine decreased mean 24-h diastolic blood pressure by 6.7 and 4.3 mmHg, respectively, with no significant difference between the two drugs. Mean 24-h systolic blood pressure also decreased after felodipine and nifedipine, with no difference between the two drugs. Both drugs reduced blood pressure variability, lowering the 24-h mean standard deviation of mean hourly blood pressure values. The trough:peak ratio for felodipine was 80% for systolic and 75% for diastolic blood pressure. Conclusion: Felodipine ER once daily lowers blood pressure in elderly hypertensives and is as effective as nifedipine SR twice daily. The high trough:peak ratio suggests that the dose and the between-dose interval of felodipine provides adequate therapeutic coverage.

BACKGROUND AND HYPOTHESIS: Alteration in sympathovagal balance may be a mechanism of increased cardiovascular mortality and sudden death of patients with anorexia nervosa. This study was undertaken to characterize cardiac autonomic control in patients with anorexia nervosa by means of heart rate variability analysis. METHODS: Heart period variability by 24-h Holter recording was evaluated in 13 young women with anorexia nervosa, 10 constitutionally thin women, and 10 women of normal weight. RESULTS: High-frequency power, a measure of parasympathetic modulation of heart rate, and all-time domain measures of heart rate variability were higher in patients with anorexia nervosa than in thin women and in those of normal weight. Thin women showed lower values of total power and of most components of power spectrum. CONCLUSIONS: Our data demonstrate an increased vagal tone in young women with anorexia nervosa. The marked increase in parasympathetic activity, not in response to an increase in sympathetic activity, could be detrimental and may contribute to the higher cardiovascular mortality of these patients.

A depressed heart rate variability (HRV) is a powerful predictor of poor outcome in myocardial infarction patients. The beneficial effect of specific interventions on its recovery has been reported, but data concerning calcium antagonists are scarce. We evaluated the effect of a phenylalkylamine derivative, verapamil, and a dihydropyridine derivative, felodipine, on time-and frequency-domain measurements of HRV by 24-hour Holter monitoring in 60 patients with acute myocardial infarction (AMI). After a first Holter recording (65 ± 8 hours from the onset of symptoms), patients were randomly assigned to continue standard treatment or to also receive verapamil retard (120 mg 3 times daily) or felodipine extended-release (10 mg/day). Holter recording was repeated after 7 days. After verapamil, mean RR interval increased from 823 ± 92 to 907 ± 95 ms and the SD of all normal RR (NN) intervals (SDNN) from 99 ± 24 to 120 ± 30 ms (p 50 ms (pNN50) also increased (p Heart rate variability was evaluated by means of 24-hour Holter monitoring in 60 patients with myocardial infarction, randomly assigned to standard treatment or to verapamil retard (120 mg 3 times daily) or felodipine extended-release (10 mg/day) administration. After 7 days of verapamil treatment all measures of heart rate variability significantly increased while the increase was detectable only in few components after felodipine; moreover, the low- to high-frequency ratio decreased after verapamil and remained unchanged after felodipine, suggesting that verapamil, but not felodipine, improves sympathovagal balance early after myocardial infarction.

The elongation factor 1 alpha from the archaeon Sulfolobus solfataricus (SsEF-1 alpha) was expressed in Escherichia coli and purified. The SsEF-1 alpha gene was amplified by PCR and cloned in the Ndel site of the pT7-7 expression vector, under the control of the promoter of T7 RNA polymerase. Upon induction with isopropyl beta-D-thiogalactopyranoside, the recombinant SsEF-1 alpha (recSsEF-1 alpha) was purified from the E. coli S-100 extract by a two-step procedure. From 1 litre of cell culture, about 2 mg of purified recSsEF-1 alpha was obtained. The N-terminal sequence of the first 30 amino acid residues of recSsEF-1 alpha was identical with that translated from the nucleotide sequence of the corresponding gene, except for the initial residue, which in recSsEF-1 alpha was Ser instead of Met. The M(r) of recSsEF-1 alpha (determined by electrospray MS) was almost coincident with that of the naturally occurring SsEF-1 alpha (SsEF-1 alpha). The thermal-inactivation and thermophilicity profiles of SsEF-1 alpha and recSsEF-1 alpha were identical. Concerning the functional properties, recSsEF-1 alpha was able to support poly(Phe) synthesis in vitro, to bind GDP and GTP and to elicit an NaCl-dependent GTPase activity [Masullo, De Vendittis and Bocchini (1994) J. Biol. Chem. 269, 20376-20379] with the same efficiency as that displayed by SsEF-1 alpha.

The Sulfolobus solfataricus S12, S7 and S10 ribosomal proteins and the elongation factor 1 alphagenes are organized in a sequence analogous to that in the Escherichia coli str operon. Northern analysis showed that the S12 gene belongs to a transcript different from that corresponding to the other three genes. Compared to the Sulfolobus acidocaldarius S12 and to the Methanococcus vannielii S7 proteins, the S. solfataricus S12 and S7 proteins were 33 and 47 amino acids longer respectively. These differences were eliminated if the 5' flanking regions of the S. acidocaldarius S12 and the M. vannielii S7 genes were translated from a different start codon. Despite the structural similarities between the archaeal and the bacterial str operons the S. solfataricus ribosomal proteins S12, S7 and S10 are more similar to the eukaryotic counterparts.

The cloning and sequencing of the gene coding for the archaebacterial elongation factor 1 alpha (aEF-1 alpha) was performed by screening a Sulfolobus solfataricus genomic library using a probe constructed from the eptapeptide KNMITGA that is conserved in all the EF-1 alpha/EF-Tu known so far. The isolated recombinant phage contained the part of the aEF-1 alpha gene from amino acids 1 to 171. The other part (amino acids 162-435) was obtained through the amplification of the S. solfataricus DNA by PCR. The codon usage by the aEF-1 alpha gene showed a preference for triplets ending in A and/or T. This behavior was almost identical to that of the S. acidocaldarius EF-1 alpha gene but differed greatly from that of EF-1 alpha/EF-Tu genes in other archaebacteria eukaryotes and eubacteria. The translated protein is made of 435 amino acid residues and contains sequence motifs for the binding of GTP, tRNA and ribosome. Alignments of aEF-1 alpha with several EF-1 alpha/EF-Tu revealed that aEF-1 alpha is more similar to its eukaryotic than to its eubacterial counterparts.

A Sulfolobus solfataricus genomic library cloned in the EMBL3 phage was screened using as probes synthetic oligonucleotides designed from the known amino acid sequence of a peptide obtained from the purified glyceraldehyde-3-phosphate dehydrogenase (aGAPD) protein. The screening led to the isolation of six recombinant phages (λG1–λG6) and one of them (λG4) contained the entire GAPD gene. The deduced amino acid sequence accounts for a protein made of 341 amino acids and the initial methionine is encoded by a GTG triplet. Alignment of the S. solfataricus aGAPD sequence versus GAPD from archaea, eukarya, and bacteria showed that a GAPD is very similar to other archaebacterial but not to eukaryotic or eubacterial GAPD. For known archaebacterial GAPD sequences, the rate of nucleotide substitutions per site per year showed that these sequences are homologous not only at the amino acid but also at the nucleotide level. The evolutionary rates are nearly similar to those reported for other eukaryotic genes.

The authors measured heart rate variability (HRV) during dipyridamole test (DET) in 36 patients with suspected coronary artery disease (CAD) who underwent coronary angiography for chest pain evaluation. The authors considered Group A: no CAD and negative DET results; Group B: CAD and negative DET; Group C: CAD and positive DET. After dipyridamole, in Group B and C, HRV measures of cardiac vagal control decreased and sympathetic activity increased; differently, in Group A all components of HRV decreased. Therefore, in CAD patients dipyridamole infusion induced a parasympathetic withdrawal with sympathetic predominance despite a negative DET. HRV analysis seems to be able to detect this autonomic disturbance, improving the diagnostic accuracy of DET in patients with suspected CAD.

The guanine nucleotide exchange factor EF-1beta gene from the thermoacidophilic archaeon Sulfolobus solfataricus (SsEF-1beta) was amplified by PCR and cloned into the pT7-7 expression vector. One of four selected clones harbored the T160C nucleotide substitution leading to the Y54H amino acid change in a hydrophobic region of SsEF-1beta, caused by a nucleotide misincorporation of the Taq DNA polymerase during PCR. The resulting plasmids were used to transform the Escherichia coli BL21(DE3)pLysE strain. Upon induction with isopropyl beta-d-thiogalactopyranoside about 1.4 mg of the recombinant SsEF-1beta (recSsEF-1beta) and Y54HSsEF-1beta were obtained from 1 liter of cell culture. recSsEF-1beta and Y54HSsEF-1beta were both able to catalyze the GDP/GTP exchange on SsEF-1alpha as observed with the wild-type SsEF-1beta. In addition, the heat inactivation profiles of recSsEF-1beta and Y54HSsEF-1beta were identical, being both half inactivated after 30 min treatment at 105 degrees C. These results suggest that Tyr 54 is not essential for the nucleotide exchange activity and is not involved in the thermostability of SsEF-1beta.

The elongation factor 1 alpha from the archaeon Sulfolobus solfataricus (SsEF-1 alpha) was expressed in Escherichia coli and purified. The SsEF-1 alpha gene was amplified by PCR and cloned in the Ndel site of the pT7-7 expression vector, under the control of the promoter of T7 RNA polymerase. Upon induction with isopropyl beta-D-thiogalactopyranoside, the recombinant SsEF-1 alpha (recSsEF-1 alpha) was purified from the E. coli S-100 extract by a two-step procedure. From 1 litre of cell culture, about 2 mg of purified recSsEF-1 alpha was obtained. The N-terminal sequence of the first 30 amino acid residues of recSsEF-1 alpha was identical with that translated from the nucleotide sequence of the corresponding gene, except for the initial residue, which in recSsEF-1 alpha was Ser instead of Met. The M(r) of recSsEF-1 alpha (determined by electrospray MS) was almost coincident with that of the naturally occurring SsEF-1 alpha (SsEF-1 alpha). The thermal-inactivation and thermophilicity profiles of SsEF-1 alpha and recSsEF-1 alpha were identical. Concerning the functional properties, recSsEF-1 alpha was able to support poly(Phe) synthesis in vitro, to bind GDP and GTP and to elicit an NaCl-dependent GTPase activity [Masullo, De Vendittis and Bocchini (1994) J. Biol. Chem. 269, 20376-20379] with the same efficiency as that displayed by SsEF-1 alpha.

The elongation factor 1 beta (EF-1 beta), that in eukarya and archaea promotes the replacement of GDP by GTP on the elongation factor 1 alpha x GDP complex, was purified to homogeneity from the thermoacidophilic archaeon Sulfolobus solfataricus (SsEF-1 beta). Its primary structure was established by sequenced Edman degradation of the entire protein or its proteolytic peptides. The molecular weight of SsEF-1 beta was estimated as about 10000 or 20000 under denaturing or native conditions respectively; this finding suggests that the native protein exists as a dimer. The peptide chain of SsEF-1 beta is much shorter than that of its eukaryotic analogues and homology is found only at their C-terminal region; no homology exists between SsEF-1 beta and eubacterial EF-Ts. At 50 degrees C, at a concentration of SsEF-1 beta 5-fold higher than that of SsEF-1 alpha x [3H]GDP the rate of the exchange of [3H]GDP for GTP becomes about 160-fold faster. An analysis of the values of the energetic parameters indicates that in the presence of SsEF-1 beta the GDP/GTP exchange is entropically favoured. At 100 degrees C the half-life of SsEF-1 beta is about 4 h.

Glyceraldehyde-3-phosphate dehydrogenase in the archaeon Sulfolobus solfataricus (SsGAPD) has been purified 232 fold with an overall recovery of about 25%. The enzyme is a homomeric tetramer with an M(r) of 41 kDa/subunit. It utilizes either NAD+ or NADP+ as coenzyme but its affinity for the latter is about 50 fold higher. SsGAPD activity is maximum at 87 degrees C. In the range 45-87 degrees C the Arrhenius plot is linear and the activation energy is 55 kJ/mol. The enzyme is thermostable, with a half-life of 45 min at 87 degrees C. The primary structure of SsGAPD shows 35% identity with that of other archaeal GAPDs. Its N-domain shows sequence motifs typical of the dinucleotide binding proteins while the catalytic C-terminal region contains a cysteine residue (C140), required for catalysis, that is conserved in all the archaeal, eukaryal and bacterial GAPDs. These remarks suggest that archaeal GAPDs show a convergent molecular evolution to the eukaryal and eubacterial enzymes in the catalytic region.