Myocardial metabolic effects of intravenous terbutaline in patients with severe heart failure due to coronary artery disease

Intravenous terbutaline, 0.3 mg/kg/min for 30 minutes followed by 0.15 mg/min for 60 minutes, was studied in nine patients with severe heart failure due to documented coronary artery disease. Hemodynamic and myocardial metabolic effects were measured during terbutaline infusion. Cardiac index and stroke index increased, whereas mean pulmonary artery wedge pressure and pulmonary vascular resistance decreased significantly. No significant alterations in aortic oxygen content, coronary sinus oxygen content, myocardial oxygen extraction, and myocardial lactate extraction were observed during terbutaline infusion. No patient developed angina or electrocardiographic changes suggestive of ischemia. These results indicate that intravenous terbutaline infusion, at the dosage employed, produces beneficial hemodynamic effects without a deterioration of myocardial metabolism in patients with heart failure due to coronary artery disease.

Terbutaline infusion in cardiogenic shock: acute hemodynamic effects and clinical response

The effect of terbutaline infusion was studied in six patients with cardiogenic shock due to acute myocardial infarction. Terbutaline was initiated at 3 micrograms/kg/min, and the subsequent infusion rate was adjusted according to heart rate and blood pressure. At 3 hours after infusion arterial pressure increased from 62 +/- 13 mm Hg (mean +/- S.D.) to 89 +/- 13 mm Hg (P less than 0.001), cardiac index increased from 1.38 +/- 0.29 liter/min/m2 to 2.68 +/- 0.47 liter/min/m2 (P less than 0.001), and heart rate increased from 92 +/- 32 beats/min to 112 +/- 29 beats/min (P less than 0.005). Pulmonary artery wedge pressure fell from 24 +/- 7 mm Hg to 17 +/- 3 mm Hg (P less than 0.01), right atrial pressure fell from 12 +/- 4 mm Hg to 6 +/- 3 mm Hg (P less than 0.005), and systemic vascular resistance fell from 1880 +/- 641 dyn-sec/cm5 to 1515 +/- 418 dyn-sec/cm5 (P less than 0.05). In addition, urine flow increased from 4 +/- 6 ml/hr to 314 +/- 237 ml/hr (P less than 0.05), and subjective improvement was noted in all subjects. Undesirable effects observed were hypokalemia (all subjects), supraventricular tachycardia (one subject), and ventricular ectopic beats (three subjects), which responded to potassium replacement and other treatments. All patients required prolonged maintenance infusion to maintain adequate hemodynamic and clinical response. Four patients were weaned off from maintenance therapy after a mean duration of 4.8 days and eventually were discharged from the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous ranitidine has no hemodynamic effects in subjects with normal lung function and patients with chronic obstructive airway disease

Ten patients with Chronic Obstructive Airway Disease (COAD) and five subjects with duodenal ulcers and normal lung function were given 50 mg ranitidine as a single intravenous bolus injection. Hemodynamic responses were continuously monitored. There were no significant alterations in systemic and pulmonary pressures, systemic and total pulmonary vascular resistances or cardiac output. Continuous ECG recordings did not reveal arrhythmias. Ranitidine does not appear to cause any significant disturbance of hemodynamic function in COAD patients. This contrasts with alterations in hemodynamics previously observed following administration of cimetidine.

The 5-methylcytosine content of highly repeated sequences in human DNA

Previously, we found much tissue- or cell-specificity in the levels of 5-methylcytosine (m5C) in the total human genome as well as in DNA fractions resolved by reassociation kinetics. We now report that there were even greater differences in the m5C content of the highly repeated, tandem EcoRI family of DNA sequences from different human organs or cell populations. The ratio of m5C levels in this DNA fraction from brain, placenta, and sperm was 2.0:1.2:1.0. At a HhaI site in this repeat family, sperm DNA was 5-10 fold less methylated than somatic DNAs. In contrast, the highly repeated Alu family, which is approximately 5% of the genome, had almost the same high m5C content in brain and placenta despite marked tissue-specific differences in m5C levels of the single copy sequences with which these repeats are interspersed. These data show that very different degrees of change in methylation levels of various highly repeated DNA sequences accompany differentiation.

Comparison of the effects of chronic haloperidol treatment on A9 and A10 dopamine neurons in the rat

The effects of chronic haloperidol (CHAL) treatment on A9 and A10 dopamine (DA) neurons were compared using extracellular single cell recording techniques. CHAL caused a time-dependent reduction in the number of spontaneously active A9 and A10 DA cells and induced an irregular firing pattern in many of the DA cells that remained active. Both of these effects occurred earlier and to a greater extent in A10 than in A9. Intravenous injection of the DA agonist apomorphine reversed both the reduction of active DA neurons and the irregular discharge pattern, suggesting that both effects were due to the process of depolarization inactivation. Lesions of the nucleus accumbens (NAc) produced by ibotenic acid prevented the development of depolarization inactivation of A10 DA neurons, indicating that this process is mediated primarily by NAc-A10 feedback pathways. The results suggest that the slow development of depolarization inactivation of DA cells produced by CHAL may contribute to the delayed onset of the clinical effects of long-term treatment with antipsychotic drugs.

Mexiletine in the treatment of recurrent ventricular tachycardia. Prediction of long-term arrhythmia suppression from acute and short-term response

Acute intravenous and short-term oral mexiletine therapy was effective in suppressing the arrhythmia in six of eight patients with recurrent ventricular tachycardia. Five of the six patients who were placed on maintenance therapy remained asymptomatic during a mean follow-up of 15 months. The study shows that the acute and short-term suppression of ventricular tachycardia by mexiletine can be a useful predictor of its long-term efficacy.

Beneficial hemodynamic effects of intravenous terbutaline in patients with severe heart failure

The hemodynamic effects of terbutaline infusion at rates of 0.15, 0.3, and 0.45 micrograms/kg/min were studied and compared in eight patients with severe heart failure. Terbutaline infusion at 0.15 micrograms/kg/min infusion produced insignificant effects at 30 minutes. At 0.3 micrograms/kg/min infusion highly significant beneficial hemodynamic effects were observed: at 60 minutes cardiac index increased from 1.79 +/- 0.38 to 3.60 +/- 0.96 (mean +/- SD) L/min/m2 (p less than 0.0001) and stroke volume index increased from 20.1 +/- 6.2 to 36.7 +/- 13.1 ml/beat/m2 (p less than 0.0001); mean pulmonary artery wedge pressure fell from 27.5 +/0- 5.5 to 18.5 +/- 5.7 mm Hg (p less than 0.0001); systemic vascular resistance fell from 2624 +/- 586 to 1455 +/- 500 dynes . sec . cm-5/m2 (p less than 0.0001); and pulmonary vascular resistance fell from 248 +/- 84 to 150 +/- 70 dynes . sec . cm-5/m2 (p less than 0.0005). Mean arterial pressure and O2 uptake did not change significantly; however, mean heart rate increased from 93.4 +/- 22 to 103.1 +/- 26 bpm (p less than 0.005) and plasma potassium fell from 3.86 +/- 0.14 to 3.12 +/ 0.23 mEq/L (p less than 0.05). The 0.45 micrograms/kg/min infusion at 30 minutes produced no greater hemodynamic changes than that from 0.3 micrograms/kg/min. Our study suggests that intravenous terbutaline produces beneficial effects and may be useful in the acute management of severe heart failure.

Is cardiac catheterisation necessary before valvular surgery?

The results of 269 patients who had undergone valvular operations during and 18-month period (January 1, 1980, to June 30, 1981) were analysed. One hundred and seventy-four patients referred for surgery had undergone routine cardiac catheterisation elsewhere, and these, together with four electively catheterised patients, constituted a group representing the conventional approach. Ninety-one patients were assessed only by clinical and non-invasive methods, including echocardiography, and were subjected to surgery without catheterisation. The two groups were comparable in their major clinical characteristics including age, sex ratio, functional class, previous history of closed mitral valvotomy, aetiology of valve lesions, and type of operative procedure performed. There was no discordance between operative finding and preoperative assessment, except in two patients of the catheterised group. Hospital mortality was acceptably low and was comparable between the two groups. Cardiac catheterisation is, thus, no longer necessary in the majority of patients undergoing surgery for valvular heart diseases.

Heat- and alkali-induced deamination of 5-methylcytosine and cytosine residues in DNA

5-methylcytosine residues in DNA underwent deamination at high temperatures. Furthermore, their rate of deamination at neutral or alkaline pH was greater than that of cytosine residues in DNA. As sources of [14C]-5-methylcytosine-containing DNA, we used bacteriophage XP-12 DNA, in which 5-methylcytosine residues completely replace C residues, and calf thymus DNA experimentally substituted with [14C] 5-methylcytosine residues. Upon incubation at 95 degrees C in a physiological buffer or at 60 degrees C in 1 M NaOH, the respective rates of deamination of 5-methylcytosine residues were about 3- and 1.5-times those on cytosine residues. Under the same conditions, the free 5-methyldeoxycytidine was converted to thymidine more rapidly than deoxycytidine was converted to deoxyuridine. The reactions at physiological pH and elevated temperature suggest that deamination of 5-methylcytosine residues may yield a significant portion of spontaneous mutations in vivo, especially in view of the lack of thymine-specific mismatch repair systems with specificity and efficiency comparable to that of uracil excision repair systems.

5-methyl-dCTP deaminase induced by bacteriophage XP-12

Bacteriophage XP-12, whose DNA contains 34 mol% 5-methylcytosine, induces the synthesis of a unique enzyme, 5-methyl-dCTP deaminase. The substrate for this enzyme, 5-methyl-dCTP, is produced by reactions catalyzed in part by other phage-induced enzymes, and the product of the reaction is dTTP. The deaminase therefore provides a novel pathway for biosynthesis of thymine residues for phage XP-12 DNA. Evidence is presented that this pathway is used for dTTP synthesis in XP-12-infected Xanthomonas oryzae.

A bacteriophage-induced 5-methyldeoxycytidine 5'-monophosphate kinase

Bacteriophage XP-12-infected Xanthomonas oryzae have been found to be a source of a kinase preparation which converts m5dCMP to m5dCDP and then to m5dCTP using ATP as the phosphate donor. Optimal formation of the triphosphate required the presence of creatine phosphate and creatine kinase. In the presence of dGTP, dTTP and dATP, Escherichia coli DNA polymerase I and T4 DNA polymerase catalyzed the incorporation of m5dCTP into DNA just as efficiently as that of dCTP. Neither dTMP nor dCMP served as substrate for the m5dCMP monophosphate kinase. Analogous preparations from uninfected X. oryzae were unable to phosphorylate m5dCMP.

Correlative firing patterns of serotonergic neurons in rat dorsal raphe nucleus

In this study, local neuronal interactions in the midbrain dorsal raphe nucleus (DRN) were analyzed by the use of autocorrelation and cross-correlation histograms. The autocorrelograms of serotonin (5-hydroxytryptamine; 5-HT)-containing cells showed an initial trough and subsequent periodicity which corresponded to their regular rhythmic firing pattern. Cross-correlograms revealed that all adjacent 5-HT neurons recorded from single micropipettes displayed complicated patterns of functional interactions. The interactions could be grouped into the following categories: (1) synchronization (interspike intervals less than 10 msec), (2) synchronization and direct inhibition, (3) synchronization and mutual inhibition. In contrast, cross-correlograms generated from adjacent neuronal pairs consisting of one 5-HT cell and one non-5-HT neuron or from non-adjacent 5-HT neuronal pairs usually failed to show functional interactions. The results of the present study are consistent with previous findings of a powerful auto-and mutual regulatory system for 5-HT neurons in the DRN.

Pregnancy in patients with prosthetic heart valves: an experience with 45 pregnancies

Between 1974 and 1981, 27 patients became pregnant after prosthetic heart valve replacement with a total of 45 pregnancies. Four pregnancies terminated in therapeutic abortions. Of the remaining 41 pregnancies, 30 were associated with the use of anticoagulants and 11 not. Haemorrhage related to anticoagulant therapy occurred in one patient. The foetal loss in the group with anticoagulant therapy was 33 per cent (10 abortions) and that in the group without was 9 per cent (one abortion). The use of aspirin and dipyridamole during pregnancy (eight pregnancies) did not appear to threaten the outcome of pregnancy. A total of 30 babies were born alive and 20 per cent of them were light for date. There was no perinatal mortality. The typical warfarin embryopathy was not found. Congenital anomalies in four newborns included congenital hydrocephalus, harelip and complete cleft palate, bilateral accessory auricles and bilateral incurving 5th fingers. Subsequently, all except the newborn with congenital hydrocephalus showed normal developmental milestones.

5-Methylcytosine in eukaryotic DNA

A small portion of the cytosine residues in the DNA of higher eukaryotes as well as in that of many lowe eukaryotes if methylated. The resulting 5-methylcytosine residues occur in specific in the DNA, usually adjacent to guanine residues on the 3' side. This methylation of eukaryotic DNA has been proposed to function in many ways, including control of transcription, maintenance of chromosome structure, repair of DNA, establishment of preferred sites for mutation, oncogenic transformation, and, in certain systems, protection of DNA against enzymatic degradation.

Monoaminergic denervation of the rat hippocampus: microiontophoretic studies on pre- and postsynaptic supersensitivity to norepinephrine and serotonin

The responsiveness of hippocampal CA3 pyramidal neurons to microiontophoretic applications of serotonin (5-HT), norepinephrine (NE), gamma-aminobutyric acid (GABA) and isoproterenol (ISO) was assessed in rats following 5,7-dihydroxy-tryptamine (5,7-DHT) and 6-hydroxydopamine (6-OHDA) pretreatments and bilateral locus coeruleus lesions. The intraventricular administration of 200 micrograms (free base) of 5,7-DHT and of 6-OHDA produced 89% and 93% decreases of 5-HT and NE respectively. None of these pretreatments modified the inital responsiveness to, or recovery from iontophoretic application of 5-HT. In 6-OHDA pretreated and locus-lesioned rats, the initial effectiveness of NE was not altered but its effect was markedly prolonged. However, there was no such prolongation of the effect of ISO which is not a substrate for the high affinity NE reuptake. The effect of GABA was not affected by these pretreatments. Acute pharmacological blockade of the NE reuptake with desipramine (5 mg/kg, i.p.) similarly induced a prolongation of the effect of iontophoretically applied NE, while fluoxetine (10 mg/kg, i.p.) a 5-HT reuptake blocker, failed to alter the recovery of pyramidal cells from iontophoretic application of 5-HT. It is concluded that 5-HT denervation induces neither pre- nor postsynaptic types of supersensitivity in hippocampal pyramidal cells, contrasting with the previously shown supersensitivity of ventral lateral geniculate and amygdaloid neurons following 5-HT denervation. NE denervation fails to induce a postsynaptic type of supersensitivity but leads to a marked prolongation of the response to NE indicative of a presynaptic mechanism. These results underscore the necessity for regional studies of neurotransmitters and drug action.

Comparison of bisulfite modification of 5-methyldeoxycytidine and deoxycytidine residues

Sodium bisulfite is a mutagen which can specifically deaminate more than 96% of the cytosine residues in single-stranded DNA via formation of a 5,6-dihydrocytosine-6-sulfonate intermediate. Under the same reaction conditions, only 2-3% of the 5-methylcytosine (m5Cyt) residues in single-stranded XP-12 DNA, which has 34 mole% m5Cyt, was converted to thymine (Thy) residues. In contrast, at the deoxynucleoside and free base levels, the same treatment with bisulfite and then alkali converted 51% and > 95%, respectively, of the m5Cyt to the corresponding Thy derivatives. However, the rate of reaction of m5Cyt and its deoxyribonucleoside was much slower than that of the analogous quantitative conversion of cytosine or deoxycytidine to uracil or deoxyuridine, respectively. The much lower reactivity of m5Cyt and its derivatives compared to that of the unmethylated analogs is primarily due to a decrease in the rate of formation of the sulfonate adduct.