N,N'-Dimethylpiperazinium(2+) phosphonoacetate: hydrogen-bonded anion sheets containing cation-templated R(6)(6)(28) rings.

In the title compound, C(6)H(16)N(2)(2+).2C(2)H(4)O(5)P(-), the cations lie across centres of inversion; in the anions, two of the H-atom sites have 0.50 occupancy. The anions are linked by short O-H...O hydrogen bonds [O...O 2.465 (3)-2.612 (3) A and O-H...O 165-171 degrees ] into sheets of alternating R(2)(2)(12) and R(6)(6)(28) rings, both of which are centrosymmetric; the cations lie at the centres of the larger rings linked to the anion sheet by N-H...O hydrogen bonds [N...O 2.642 (2) A and N-H...O 176 degrees ].

Hydrogen-bonded bilayers in piperazinium(2+) bis(mandelate) bis(methanol) solvate.

In the title compound, C(4)H(12)N(2)(2+).2C(8)H(7)O(3)(-).2CH(4)O, the cations lie across centres of inversion and are disordered over two orientations with equal occupancy; there are equal numbers of (R)- and (S)-mandelate anions present (mandelate is alpha-hydroxybenzeneacetate). The anions and the neutral water molecules are linked by O-H...O hydrogen bonds [O...O 2.658 (3) and 2.682 (3) A, and O-H...O 176 and 166 degrees] into deeply folded zigzag chains. Each orientation of the cation forms two symmetry-related two-centre N-H...O hydrogen bonds [N...O 2.588 (4) and 2.678 (4) A, and N-H...O 177 and 171 degrees] and two asymmetric, but planar, three-centre N-H...(O)(2) hydrogen bonds [N...O 2.686 (4)-3.137 (4) A and N-H...O 137-147 degrees], and by means of these the cations link the anion/water chains into bilayers.

Angiotensin II modulates catecholamine release into interstitial fluid of canine myocardium in vivo.

This study tested the hypothesis that exogenous infusion of angiotensin II (ANG II) leads to the release of catecholamines [norepinephrine (NE) and epinephrine (EPI)] into the cardiac interstitial fluid (ISF) space of dogs with adrenals intact (AI) (n = 7) and with adrenals clamped (AC) (n = 5). LV ISF samples were collected at 3-min intervals during administration of ANG II (100 microM ANG II at 1 ml/min for 10 min) to right atrial neurons via their local arterial blood supply and during electrical stimulation of the stellate ganglia of open-chest anesthetized dogs. In AI dogs, ANG II caused ISF NE to increase fivefold (P < 0.05) without a significant increase in coronary sinus (CS) NE. Electrical stimulation (5 ms, 4 Hz, 8-14 V, and 10 min) of the stellate ganglia caused a similar increase in ISF NE (P < 0.05), accompanied by a sevenfold increase in CS NE (P < 0.05). ISF EPI increased greater than sixfold during ANG II infusion (P < 0.05) and during stellate stimulation. However, during ANG II infusions, aorta plasma EPI levels increased fourfold in AI dogs, whereas in AC dogs, CS NE and EPI levels were unaffected during ANG II infusions. Nevertheless, baseline ISF NE and EPI did not differ and increased to a similar extent during ANG II infusions in AI versus AC dogs. Thus exogenously administered ANG II increases the amount of NE liberated into the ISF independent of the adrenal contribution, the amount matching that induced by electrical stimulation of all cardiac sympathetic efferent neurons. In contrast, NE spillover into the CS occurred only during electrical stimulation of stellate ganglia. NE release and uptake mechanisms within the myocardium are differently affected, depending on how the final common pathway of the sympathetic efferent nervous system is modified.

Evidence for angiotensin-converting enzyme- and chymase-mediated angiotensin II formation in the interstitial fluid space of the dog heart in vivo.

BACKGROUND: We have previously demonstrated that angiotensin II (Ang II) levels in the interstitial fluid (ISF) space of the heart are higher than in the blood plasma and do not change after systemic infusion of Ang I. In this study, we assess the enzymatic mechanisms (chymase versus ACE) by which Ang II is generated in the ISF space of the dog heart in vivo. METHODS AND RESULTS: Cardiac microdialysis probes were implanted in the left ventricular (LV) myocardium (3 to 4 probes per dog) of 12 anesthetized open-chest normal dogs. ISF Ang I and II levels were measured at baseline and during ISF infusion of Ang I (15 micromol/L, n=12), Ang I+the ACE inhibitor captopril (cap) (2.5 mmol/L, n=4), Ang I+the chymase inhibitor chymostatin (chy) (1 mmol/L, n=4), and Ang I+cap+chy (n=4). ISF infusion of Ang I increased ISF Ang II levels 100-fold (P<0.01), whereas aortic and coronary sinus plasma Ang I and II levels were unaffected and were 100-fold lower than ISF levels. Compared with ISF infusion of Ang I alone, Ang I+cap (n=4) produced a greater reduction in ISF Ang II levels than did Ang I+chy (n=4) (71% versus 43%, P<0.01), whereas Ang I+cap+chy produced a 100% decrease in ISF Ang II levels. CONCLUSIONS: This study demonstrates for the first time a very high capacity for conversion of Ang I to Ang II mediated by both ACE and chymase in the ISF space of the dog heart in vivo.

The roles of cGMP and cAMP in active thermoregulatory vasodilation.

This study was designed to test the hypothesis that active thermoregulatory vasodilation (AVD) is the result of a neurotransmitter-induced adenosine 3',5'-cyclic monophosphate (cAMP) pathway interacting with a nitric oxide-induced guanosine 3',5'-cyclic monophosphate (cGMP) pathway. Rabbits were instrumented for measurement of arterial pressure and ear blood flow (EBF) and the infusion of drugs. In four groups of conscious animals, whole-body heating increased EBF from 0.5 +/- 0.3 to 8.3 +/- 1.3 kHz. In group 1 (n = 6), N(omega)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor, 10-40 mg) reduced EBF from 7.1 +/- 0.9 to 1.9 +/- 0.5 kHz. Subsequent infusion of 8-bromo-cGMP (a cGMP analog, 5-10 mg) returned EBF to 6.2 +/- 0.7 kHz. In group 2 (n = 3), (R)-p-adenosine 3',5'-cyclic monophosphothioate (a cAMP-dependent protein kinase inhibitor, 10 mg) reduced EBF to 1.6 +/- 0.4 kHz. In group 3 (n = 6), nerve blockade of the ear (procaine, 20 mg/ml, 1.5 ml) reduced EBF from 8.6 +/- 1.3 to 1.6 +/- 0.3 kHz. Subsequent infusion of 8-bromo-cAMP (a cAMP analog, 5-10 mg) returned EBF to 8.3 +/- 2.0 kHz. In group 4 (n = 6), the infusion of L-NAME caused EBF to fall from 9.0 +/- 1.1 to 1.2 +/- 0.3 kHz. Infusion of the cAMP phosphodiesterase inhibitor Ro 20-1724 (0.2-0.5 mg) raised EBF to 5.5 +/- 0.7 kHz. These results suggest that cGMP plays a permissive role in AVD and indicate that the transmitter acts through cAMP.

Perioperative effects of alpha-stat versus pH-stat strategies for deep hypothermic cardiopulmonary bypass in infants.

OBJECTIVES: In a randomized, single-center trial, we compared perioperative outcomes in infants undergoing cardiac operations after use of the alpha-stat versus pH-stat strategy during deep hypothermic cardiopulmonary bypass. METHODS: Admission criteria included reparative cardiac surgery, age less than 9 months, birth weight 2.25 kg or more, and absence of associated congenital or acquired extracardiac disorders. RESULTS: Among the 182 infants in the study, diagnoses included D-transposition of the great arteries (n = 92), tetralogy of Fallot (n = 50), tetralogy of Fallot with pulmonary atresia (n = 6), ventricular septal defect (n = 20), truncus arteriosus (n = 8), complete atrioventricular canal (n = 4), and total anomalous pulmonary venous return (n = 2). Ninety patients were assigned to alpha-stat and 92 to pH-stat strategy. Early death occurred in four infants (2%), all in the alpha-stat group (p = 0.058). Postoperative electroencephalographic seizures occurred in five of 57 patients (9%) assigned to alpha-stat and one of 59 patients (2%) assigned to pH-stat strategy (p = 0.11). Clinical seizures occurred in four infants in the alpha-stat group (4%) and two infants in the pH-stat group (2%) (p = 0.44). First electroencephalographic activity returned sooner among infants randomized to pH-stat strategy (p = 0.03). Within the homogeneous D-transposition subgroup, those assigned to pH-stat tended to have a higher cardiac index despite a lower requirement for inotropic agents; less frequent postoperative acidosis (p = 0.02) and hypotension (p = 0.05); and shorter duration of mechanical ventilation (p = 0.01) and intensive care unit stay (p = 0.01). CONCLUSIONS: Use of the pH-stat strategy in infants undergoing deep hypothermic cardiopulmonary bypass was associated with lower postoperative morbidity, shorter recovery time to first electroencephalographic activity, and, in patients with D-transposition, shorter duration of intubation and intensive care unit stay. These data challenge the notion that alpha-stat management is a superior strategy for organ protection during reparative operations in infants using deep hypothermic cardiopulmonary bypass.

Isochromosomes in acute lymphoblastic leukaemia: i(21q) is a significant finding.

The incidence, type, and clonality of isochromosomes at diagnosis were investigated in acute lymphoblastic leukaemia (ALL). An isochromosome was detected in 50/1,035 (4.8%) of successfully karyotyped patients, 41/919 children (4.5%) and 9/116 adults (7.8%), who were diagnosed within a 5 year period. Isochromosomes of 21q with breakpoints in the short arm at p11 or in the long arm at q10 or q22 were identified in 15 patients (1.4%) associated with B-lineage immunophenotype, a white blood cell count (WBC) of < 10 x 10(9)/litre, and pseudo- or low hyperdiploidy. Isochromosomes of 17q and 7q occurred in 13 (1.3%) and 9 (0.9%) patients, respectively, and were associated with high hyperdiploidy. Isochromosomes of 9q and 6p occurred in 6 (0.6%) and 5 (0.5%) patients, respectively, whereas i(Xp), i(lq), and i(8q) occurred in I patient each. The isochromosome occurred as the sole abnormality in 4 patients [3 with i(21q) and I with i(7q)] and in the stemline, but with other chromosomal changes, in 35 patients. It was confined to a clonally evolved sideline in II patients. Isochromosomes occurred with established abnormalities in 7 patients: with t(1;19)-i(7q)/i(9q)/i(7q) and i(9q) each in I patient; with t(4;11)-i(7q)/i(17q) in 1 and 2 patients, respectively; and with t(9;22)-i(9q) in I patient. This study indicates that isochromosome formation can be an early chromosomal change and suggests that i(21q) occurs more frequently at diagnosis than has been previously suspected.

Probes for hidden hyperdiploidy in acute lymphoblastic leukaemia.

The detection of hyperdiploidy (clones with >46 chromosomes) in the bone marrow of patients with acute lymphoblastic leukaemia (ALL) is important because of the prognostic impact of this finding. The high hyperdiploid (HeH) subgroup with 51-68 chromosomes is associated with the best outcome, followed by the low hyperdiploid (HeL) subgroup with 47-50 chromosomes and the triploid/tetraploid (TT) subgroup with >68 chromosomes, which do less well. We present a strategy for the use of fluorescence in situ hybridization (FISH) with chromosome-specific probes to detect hyperdiploidy in interphase cells and to assign cases to a ploidy subgroup. By using a model population of 252 cases, it was seen that ten chromosomes (X, 4, 6, 8, 10, 14, 16, 18, 20, and 21) used in particular combinations and applied in a step-wise manner enabled the detection of 94% of hyperdiploid cases and gave an accurate prediction of ploidy subgroup in 96% of these cases. The detection and classification of each case required the use of four to six probes over two or three steps. Confirmation that this strategy will achieve this level of detection in other hyperdiploid populations was demonstrated by using 250 published karyotypes. This strategy has an application in detecting missing or hidden hyperdiploid cases among cases with failed or normal cytogenetics.

Permissive role for nitric oxide in active thermoregulatory vasodilation in rabbit ear.

The present study was designed to test the hypothesis that during whole body heating (WBH), nitric oxide (NO) synthesized in the endothelium acts synergistically with an unknown neurotransmitter to elicit active vasodilation. Rabbits were instrumented for the measurement of mean arterial pressure, heart rate, and ear blood flow (EBF) (Doppler ultrasound). During WBH, either N omega-nitro-L-arginine methyl ester (L-NAME, 10-40 mg over 10-15 min, n = 6 rabbits; group 1), a NO synthase inhibitor, or saponin (30-40 mg over 10-20 min, n = 6 rabbits; group 2), a detergent that denudes the endothelium, was given via a lingual artery catheter until thermoregulatory vasodilation was reversed. When EBF stabilized at the new reduced level, the NO donor, sodium nitroprusside (SNP), was infused (0.2-1.0 mg/ml, 0.01-0.05 ml/min, 2-5 min) via the lingual artery catheter. During WBH, EBF increased from 0.39 +/- 0.08 to 6.47 +/- 0.63 kHz in group 1, and from 0.69 +/- 0.18 to 5.72 +/- 0.49 kHz in group 2. Infusion of L-NAME decreased EBF in group 1 to 1.97 +/- 0.40 kHz. Infusion of saponin decreased EBF in group 2 to 1.23 +/- 0.40 kHz. Subsequent SNP infusion during hyperthermia returned EBF to 6.88 +/- 0.72 kHz in group 1 and 5.53 +/- 1.27 kHz in group 2 but had no effect when administered during normothermia. These results suggest that NO acts in conjunction with another substance, presumably the neurotransmitter released on WBH, to elicit thermoregulatory vasodilation.

A comparison of the perioperative neurologic effects of hypothermic circulatory arrest versus low-flow cardiopulmonary bypass in infant heart surgery.

BACKGROUND: Hypothermic circulatory arrest is a widely used support technique during heart surgery in infants, but its effects on neurologic outcome have been controversial. An alternative method, low-flow cardiopulmonary bypass, maintains continuous cerebral circulation but may increase exposure to known pump-related sources of brain injury, such as embolism or inadequate cerebral perfusion. METHODS: We compared the incidence of perioperative brain injury after deep hypothermia and support consisting predominantly of total circulatory arrest with the incidence after deep hypothermia and support consisting predominantly of low-flow cardiopulmonary bypass in a randomized, single-center trial. The criteria for eligibility included a diagnosis of transposition of the great arteries with an intact ventricular septum or a ventricular septal defect and a planned arterial-switch operation before the age of three months. RESULTS: Of 171 patients with D-transposition of the great arteries, 129 (66 of whom were assigned to circulatory arrest and 63 to low-flow bypass) had an intact ventricular septum, and 42 (21 assigned to circulatory arrest and 21 to low-flow bypass) had a ventricular septal defect. After adjustment for diagnosis, assignment to circulatory arrest as compared with low-flow bypass was associated with a higher risk of clinical seizures (odds ratio, 11.4; 95 percent confidence interval, 1.4 to 93.0), a tendency to a higher risk of ictal activity on continuous electroencephalographic (EEG) monitoring during the first 48 hours after surgery (odds ratio, 2.5; 95 percent confidence interval, 1.0 to 6.4), a longer recovery time to the first reappearance of EEG activity (only in the group with an intact ventricular septum, P < 0.001), and greater release of the brain isoenzyme of creatine kinase in the first 6 hours after surgery (P = 0.046). Analyses comparing durations of circulatory arrest produced results similar to those of analyses comparing treatments. CONCLUSIONS: In heart surgery in infants, a strategy consisting predominantly of circulatory arrest is associated with greater central nervous system perturbation in the early postoperative period than a strategy consisting predominantly of low-flow cardiopulmonary bypass. Assessment of the effect of these findings on later outcomes awaits follow-up of this cohort.

Relation of pH strategy and developmental outcome after hypothermic circulatory arrest.

To examine whether pH management during core cooling is a risk factor for adverse developmental outcome, we studied 16 children with transposition of the great arteries and intact ventricular septum who underwent a Senning procedure in infancy (median age 32 days, range 2 to 154 days) between 1983 and 1988. Information was collected retrospectively on many aspects of perfusion, including lowest carbon dioxide tension during core cooling, duration of core cooling, and duration of circulatory arrest. The pH strategy changed from pH-stat to alpha-stat in 1985, resulting in a wide range of pH values and carbon dioxide tension (34 to 76 mm Hg) during the study period. All children had rapid core cooling to a rectal temperature of 19.8 degrees +/- 2.7 degrees C (mean +/- standard deviation) and a tympanic temperature of 16.6 degrees +/- 3.0 degrees C. Development was assessed at median age 48.0 (11 to 79) months with the Bayley Scales (n = 4, children younger than 30 months) or the McCarthy Scales (n = 12, children older than 30 months). The mean core-cooling duration was 14.5 +/- 6.2 minutes, circulatory arrest time was 43.4 +/- 6.6 minutes, and total bypass plus circulatory arrest time was 89.7 +/- 12.7 minutes. Lower carbon dioxide tension (alpha-stat) before onset of circulatory arrest was associated with worse developmental outcome (r = 0.71, p = 0.002). This relationship remained highly significant when we controlled for sociodemographic and intraoperative variables. including core-cooling time, circulatory arrest time, and total elapsed time. Duration of circulatory arrest was not associated with developmental outcome. We conclude that when relatively rapid core cooling is used to achieve hypothermia before circulatory arrest in young infants, a more alkaline pH strategy such as alpha-stat may result in less effective cerebral protection.

Factors associated with choreoathetosis after cardiopulmonary bypass in children with congenital heart disease.

BACKGROUND: Choreoathetosis (CHO) after congenital heart surgery has been described since 1960. Risk factors and patient outcome have not been well defined. METHODS AND RESULTS: As our complexity of cases increased and management of pH on cardiopulmonary bypass (CPB) evolved, we noted the appearance of CHO among patients beginning in 1986. We reviewed the hospital course and follow-up of all 19 affected children, including eight younger patients (median age, 4.3 months) who developed a mild transient form of CHO, all of whom survived and had complete resolution of CHO; seven of these eight patients had deep hypothermic circulatory arrest (DHCA). Eleven older patients (median age, 16.8 months) developed severe persistent CHO; 11 had DHCA, 10 were cyanotic, seven had anatomic pulmonary atresia, and three others were physiologically analogous with a systemic to pulmonary artery shunt-dependent circulation. Five of six patients who had pertinent preoperative angiography had systemic to pulmonary collateral vessels arising from the head and neck arteries. Mortality in severe patients was 36% (four of 11); the seven survivors showed improvement, but only one had a normal neurological examination after 60 months of follow-up. When severe CHO patients were compared with 17 age- and diagnosis-matched patients without neurological complications, no differences were found in CPB or DHCA times, arterial blood gases, or hematocrits. Time from onset of CPB to onset of DHCA (time to shutoff) was shorter in the severe persistent CHO group than for comparison patients (22 +/- 7 versus 40 +/- 29 minutes, p = 0.053). CONCLUSIONS: Factors that may be associated with the development of severe persistent CHO include 1) age beyond early infancy, 2) cyanotic heart disease with systemic to pulmonary collaterals, particularly those arising from the head and neck vessels, and 3) the duration of the cooling period used in conjunction with deep hypothermic circulatory arrest. We advocate earlier reparative surgery, precise preoperative diagnosis and preoperative or intraoperative control of systemic to pulmonary artery collaterals, and further study of pH effects during CPB on development of CHO.

Cognitive development of children following early repair of transposition of the great arteries using deep hypothermic circulatory arrest.

Twenty-eight children who underwent corrective cardiac surgery in early infancy had developmental evaluations to explore whether cardiopulmonary bypass perfusion variables are associated with later cognitive function. All had transposition of the great arteries repaired by the arterial switch operation using deep hypothermic circulatory arrest. The mean duration of deep hypothermic circulatory arrest was 64 +/- 10 minutes (mean +/- SD). Median age at repair was 4 days (range 1 to 125 days). Tests of development were administered at age 7 to 53 months: Bayley Scales for children younger than 30 months of age (n = 18) and McCarthy Scales for older children (n = 10). Overall cognitive development score was 101.2 +/- 11.1. Duration of deep hypothermic circulatory arrest was not associated with performance. However, for core cooling periods of less than 20 minutes' duration, shorter cooling periods were associated with lower scores (r = .85, n = 11, P less than .001). These data suggest that patients undergoing relatively long periods of deep hypothermic circulatory arrest may require some minimum time of cardiopulmonary bypass cooling to avoid central nervous system injury.