Treatment of pulmonary arterial hypertension in congenital heart disease in Singapore versus the Netherlands: age exceeds ethnicity in influencing clinical outcome.

BACKGROUND: Advanced treatment of pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) is increasingly applied worldwide following the-mainly Western world based-international PAH-CHD guidelines. However, studies comparing clinical presentation and outcome after the initiation of PAH-specific treatment are lacking. We aimed to analyse this in a Singaporean and Dutch cohort of PAH-CHD patients. METHODS: Adult CHD patients starting PAH-specific therapy, enrolled in two nationwide registries, were analysed. Patients received phosphodiesterase-type-5 inhibitors, endothelin receptor antagonists, or a combination. Change in six-minute walk test (6MWT) during follow-up was analysed using linear mixed model analysis. Determinants for mortality were assessed using Cox proportional hazard analyses. RESULTS: A total of 74 patients, 45 Dutch (mean age 47 ± 14 years) and 29 Singaporean (mean age 41 ± 14 years) were analysed. Despite a lower 6MWT (312 versus 395 metres, p = 0.01) and peak VO2 (35 versus 49 % of predicted, p = 0.01) at baseline in Singaporean patients, the treatment effect was similar in the two populations. Age at initiation of therapy (per 5 year lower age, ß = + 4.5, p = 0.017) was the strongest predictor of improvement in exercise capacity, corrected for ethnicity, baseline 6MWT, sex and CHD defect. CONCLUSIONS: Patients from Singapore had a worse clinical performance at baseline compared with the PAH-CHD patients from the Netherlands. No relation between ethnicity and improvement in 6MWT after PAH-specific therapy was found. Age at initiation of PAH-specific therapy was the strongest predictor of treatment efficacy and mortality, emphasising the need for early initiation of treatment in these patients.

Glomerular hyperfiltration in the prediction of nephropathy in IDDM: a 10-year follow-up study.

Glomerular hyperfiltration has been proposed as an independent risk factor for the development of diabetic nephropathy in patients with IDDM. In a case-controlled prospective study of IDDM patients without albuminuria, serial glomerular filtration rate (GFR) measurements were performed over an observation period of 10 years. A group of 25 IDDM patients (20 men, 5 women; initial age, 29 [17-49] years) with glomerular hyperfiltration (GFR >135 ml x min(-1) x 1.73 m(-2)) were matched for age, sex, and duration of diabetes with 25 IDDM patients (20 men, 5 women; initial age, 30 [17-48] years) with glomerular normofiltration (GFR 83-135 ml x min(-1) x 1.73 m(-2)). GFR, urinary albumin excretion rate (AER), blood pressure, and glycated hemoglobin were measured at baseline and at 5, 8, and 10 years. The two groups had similar entry levels of blood pressure, AER, and glycated hemoglobin. Metabolic control was similar in the two groups during follow-up. The final GFR remained higher in the group with hyperfiltration (122 [109-135] vs. 103 [95-111] ml x min(-1) x 1.73 m(-2); P = 0.02) despite a nonsignificantly faster rate of fall of GFR compared with that of the control group (2.54 [1.20-3.88] vs. 1.50 [1.01-1.99] ml x min(-1) x year(-1); P = 0.14). A similar number of patients in each group progressed to either microalbuminuria or macroalbuminuria (n = 4 vs. n = 3) or developed hypertension (blood pressure, >160/95 mmHg; n = 3 vs. n = 4). End-of-study AER was, however, higher in the group with hyperfiltration (geometric mean [95% CI]: 18.9 [11.3-31.6] vs. 11.0 [8.1-15.0]; P = 0.05), and baseline glomerular hyperfiltration was an independent determinant of end-of-study blood pressure (P = 0.04). The strongest predictors of end-of-study AER and blood pressure were their baseline values (P < 0.04 and P < 0.01, respectively). In conclusion, levels of AER and blood pressure are the main risk factors for renal outcome, while glomerular hyperfiltration appears to play a lesser role.

ReoPro Observational Registry (RAPOR): insights from the multicentre use of abciximab in Asia.

INTRODUCTION: The pattern of use of abciximab in real-life clinical patients undergoing percutaneous coronary intervention (PCI) in 11 high-volume centres in Singapore, Malaysia, Thailand, Philippines, India, Pakistan and Korea was prospectively examined. METHODS: These centres enrolled 224 consecutive patients over eight months to receive abciximab during PCI for the study. The cohort consisted of 82.1 percent males, with mean age of 55 (+/- 11) years and mean weight of 67 (+/- 17) kg. RESULTS: The use of abciximab during PCI ranged between 6.2 percent and 21.6 percent. The indications for the use of abciximab were: acute coronary syndromes (34.3 percent), complex coronary lesions (17.9 percent) and multivessel PCI (17.7 percent). Based on a risk scoring system devised for this registry, majority (60.0 percent) of the patients was considered high risk when abciximab was used. Among the patients enrolled, 36.6 percent received abciximab as a "bail-out". The overall in-hospital ischaemic event rates were low at 4.0 percent. The complication rates included major bleeding 0.7 percent, thrombocytopenia 2.7 percent and need for blood transfusion 2.8 percent. There was a trend towards a higher incidence of in-hospital non-Q myocardial infarction in the "bail-out" group (2.1 percent versus 7.3 percent, p-value equals 0.07). CONCLUSION: Abxicimab was uncommonly used among patients (9.4 percent) undergoing PCI in this Asian region, with the operators reserving it mainly for high-risk patients.

Blood pressure, sodium intake, insulin resistance, and urinary nitrate excretion.

The objective of this study was to investigate the relationships among various humoral factors thought to be involved in the regulation of blood pressure during high NaCl intake. Nineteen healthy subjects underwent sequential 5-day periods ingesting a low-sodium (25 mmol/d) or high-sodium (200 mmol/d) diet. Insulin resistance was assessed by the steady-state plasma glucose concentration at the end of a 3-hour insulin suppression test. Insulin resistance correlated inversely with natriuresis (P=0.04) and directly with increase in weight (P=0.03). The increase in mean arterial pressure associated with the high-sodium diet correlated directly with the gain in weight (P<0.05) and inversely with the increase in urinary nitrate excretion (P<0.0001). In a multiple regression model, more than 2/3 of the variance in mean arterial pressure was accounted for by the gain in weight and change in urinary nitrate excretion. The steady-state plasma glucose concentrations obtained with the 2 diets were similar, indicating that insulin resistance was unaffected by sodium intake. During high sodium intake, plasma renin activity and aldosterone decreased and plasma atrial natriuretic peptide increased; these changes did not correlate with the change in mean arterial pressure, insulin resistance, or change in urinary nitrate excretion. To the extent that urinary nitrate excretion reflects activity of the endogenous nitric oxide system, these results suggest that the salt sensitivity of mean arterial pressure may be related to blunted generation of endogenous nitric oxide. The results also demonstrate that insulin-resistant individuals have an impaired natriuretic response to high sodium intake.

Ectopic sympathetic preganglionic neurons maintain proper connectivity in the reeler mutant mouse.

The location of sympathetic preganglionic neurons (SPN) in the spinal cord of the reeler mouse mutant is abnormal. Instead of their normal location in the intermediolateral column, the majority of SPN in the reeler cluster around the central canal. To determine whether ectopically located SPN in the reeler form appropriate synaptic connections with their pre- and postsynaptic partners, we examined 1). whether the axons of descending neural pathways that normally terminate on SPN follow them to their ectopic location, and 2). whether the central autonomic neural circuit that controls sympathetic output to the kidney is organized normally in the reeler. Using antibodies against tyrosine hydroxylase, serotonin, neuropeptide Y, substance P and calcitonin gene-related peptide as markers for adrenergic, serotonergic and peptidergic terminals, we found that axons which normally innervate SPN follow these neurons to their ectopic spinal location in the reeler. Injection of pseudorabies virus into the kidney of wild type and reeler mutant mice revealed similar patterns of renal sympathetic and pre-sympathetic control circuits in the spinal cord, brainstem and forebrain. These results indicate that the presynaptic inputs and postsynaptic targets of SPN in the reeler are normal, despite the ectopic spinal location of their cell bodies.

Electrocardiographic patterns in posterior chest leads (V7, V8, V9) in normal subjects.

The electrocardiographic patterns in leads V7, V8, and V9 were studied in 225 young, normal men (age range 17 to 21 years). The prevalence of 0.5- to 1.0-mm ST-segment elevation in leads V7, V8, and Vg 0.08 second after the J point was 8.9%, 5.8%, and 3.1%, respectively; the ST-segment elevation was not >1.0 mm in any subject.

Usefulness of ST elevation II/III ratio and ST deviation in lead I for identifying the culprit artery in inferior wall acute myocardial infarction.

In a study of 92 patients presenting with inferior wall acute myocardial infarction, the infarct-related artery was the right coronary artery in 72 patients (78%) and the left circumflex artery in 20 (22%). An ST II/III ratio of 1 or an isoelectric ST in lead I are sensitive and specific markers of left circumflex artery occlusion, whereas an ST II/III ratio <1 (ST elevation in lead III >II) or ST depression in lead I are sensitive and specific markers of right coronary artery occlusion.

Insulin resistance in patients with essential hypertension can occur in the absence of microalbuminuria.

This study was initiated to see if the presence of resistance to insulin-mediated glucose disposal, glucose intolerance, and hyperinsulinemia in healthy patients with hypertension was dependent upon the coexistence of microalbuminuria. For this purpose we compared these variables in 68 individuals: 34 patients with hypertension and 34 normal volunteers. The two groups were similar in terms of age, gender distribution, body mass index, and ratio of waist to hip girth. Furthermore, although four patients with hypertension satisfied the criteria for microalbuminuria, as compared to one normal volunteer, the urinary albumin excretion (UAE) rates were similar in the two groups (8.07 +/- 1.08 v 7.67 +/- 1.12 micrograms/min). Despite the similarities, both the plasma glucose and insulin responses to a 75 g oral glucose challenge were significantly higher (P < .01) in those with high blood pressure. In addition, the steady-state plasma glucose (SSPG) concentrations at the end of a 180 min continuous infusion of somatostatin, insulin, and glucose was significantly higher in those with hypertension (156 +/- 13 v 107 +/- 10 mg/dL, P < .01). Since the steady-state plasma insulin levels were also somewhat higher in those with hypertension, the higher SSPG values indicate that these individuals were relatively insulin resistant as compared to the control population. Finally, UAE rates were not correlated with either the plasma glucose or insulin responses to oral glucose or to the SSPG concentrations--either in the entire group of 68, or when the 34 patients in each group were considered separately. These results demonstrate that insulin resistance, glucose intolerance, and hyperinsulinemia can occur independently of microalbuminuria in patients with hypertension.

A model system and technique to study the effects of ultrasound irradiation on embryonic development.

To study the effects of ultrasound on development it is important to have a system which provides reliable results. We have designed a system which allows for reproducible irradiations of chick embryos in ovo. The irradiation system includes a heated sonation tank with ultrasound absorbers and a PC/AT computer-based data acquisition system for on-line monitoring of irradiations. The ultrasound detection microprobe and irradiation transducers were calibrated against an NBS traceable balance meter. An acoustic spacer was utilized to provide a more uniform profile of the irradiation beam. At the position of the embryo the ultrasound field geometry was determined. To maintain the chick embryo in its natural physiological state while minimizing ultrasonic reflections and standing-wave generation, two diametrically opposed windows were made in the eggshell along the ultrasound pathway and covered with polyethylene membranes. Using this irradiation system at intensity levels as high as 1.1 W/cm2 (spatial average, temporal average) for 10 min, the temperature rise is minimal.

Target cues are not required for the guidance of sympathetic preganglionic axons.

The patterns of preganglionic projections in the avian sympathetic system are highly specific. Preganglionic axons arising from the T1 spinal segment, for example, project predominantly in the rostral direction, whereas T4 preganglionic axons project predominantly in the caudal direction. Moreover, each ganglion receives projections from a distinct set of spinal cord segments. These patterns are established during embryonic life and are correct from the outset. In this study, I have examined the patterns of preganglionic projections in embryos deprived of their target ganglia through removal of the neural crest prior to its migration to form the sympathetic ganglia. My results indicate that preganglionic axons of target-deprived embryos still project in the proper directions and terminate in the presumptive target regions. Target cues are thus not required for the guidance of preganglionic axons.

Size and location of the motoneuron pool supplying normal and orthotopically transplanted muscles.

Following intramuscular placement of horseradish peroxidase (HRP) into the 129ReJ mouse extensor digitorum longus muscle, 15 +/- 1 (S.E.M.) labeled motoneurons were found in the antero-lateral motor column, between the exits of spinal roots L3 and L4. When HRP was placed in 100-day orthotopic whole muscle transplants of the extensor digitorum longus muscle, the location of the motoneurons supplying the graft was similar to that of control muscle; however, the number of motoneurons innervating the grafts was variable and usually reduced (7 +/- 1 S.E.M.).

Laminin--developmental expression and role in axonal outgrowth in the peripheral nervous system of the chick.

The possible role of laminin on axon outgrowth and guidance in vivo was examined by: (1) determining its developmental expression, and relationship to outgrowth of sensory, motor and sympathetic axons in the chick embryo; and (2) evaluating the changes in the pattern of sympathetic preganglionic projections subsequent to injections of laminin, antilaminin and other laminin function blockers (JG22, INO) into their pathways during axon outgrowth. Double immunofluorescent staining for laminin and neurofilaments in peripheral nerves prior to and during initial outgrowth showed no obvious relationship between laminin and potential nerve pathways. Even though weak laminin immunostaining is apparent throughout the mesenchyme through which axons grow, the most prominent laminin immunostaining is on basement membranes of the neural tube, notochord and dermamyotome. However, as peripheral nerves mature, laminin becomes localized to nerve fascicles throughout the peripheral nervous system, beginning with the dorsal and ventral roots, and progressing later to more distal spinal nerves. Microinjections of antilaminin, JG22 (a monoclonal antibody against laminin/fibronectin receptors) and INO (a monoclonal antibody against a laminin-heparan sulfate proteoglycan complex) into the pathway of sympathetic preganglionic axons prior to and during outgrowth had no effect on the spatio-temporal patterns of sympathetic preganglionic projections. An alternate laminin-rich pathway produced by injecting laminin into the region of the sympathetic trunk immediately adjacent but caudal to the T1 spinal level also did not alter the projection of T1 preganglionic axons. These results suggest that laminin may not be crucial to the initial of peripheral axons. The localization of laminin in nerve fascicles in later stages of development suggests instead that laminin may be important in the maintenance of these structures.

Changes in fibronectin distribution in the developing peripheral nervous system of the chick.

The relationship of peripheral nerves with fibronectin was examined at different stages of the chick embryo using double immunofluorescent staining. Neurons were stained with a monoclonal antibody (E/C8) against intermediate filaments in neuronal processes, and fibronectin was stained with polyclonal antibodies. Prior to axonal outgrowth, fibronectin was distributed in a meshwork throughout the mesenchyme. However, soon after the initiation of axonal outgrowth, fibronectin began to disappear along neuronal pathways. Thus, during the period of active axonal growth, all neural tissues were marked by the striking absence of fibronectin. Interestingly, fibronectin reappeared along peripheral pathways soon after projection patterns were established. The presence of fibronectin in the substrate on which axons grow suggests that fibronectin may provide a permissive substrate for axon extension. The disappearance of fibronectin upon axon arrival suggests that neurons may modify the substrate of their pathway during outgrowth.

Axonin 1 is expressed primarily in subclasses of avian sensory neurons during outgrowth.

A 120 kDa protein, which is expressed mainly on the surface of chick sensory neurons during outgrowth, was identified by monoclonal antibody 1A12. Crossreactivity studies showed that this protein was identical to axonin 1, a member of the immunoglobulin superfamily which promotes neurite outgrowth. Using the 1A12 antibody, we show that in the peripheral nervous system of the chick, axonin 1 is present on the cell bodies and processes of cutaneous and visceral neurons, but not on muscle afferents. In the central nervous system, axonin 1 is present in sensory pathways, such as fibers of the dorsal funiculi in the spinal cord and the optic pathway. However, axonin 1 is only expressed on growing nerve fibers. Late in embryonic development, it is present only on a small population of dorsal root ganglion cells, and is entirely absent on optic fibers. The disappearance of axonin 1 in the visual pathway coincides with the arrival of optic axons at the tectum, suggesting its expression is down regulated by axonal contact with its target. The localization of this protein on the surface of neuronal membranes was confirmed by EM immunohistochemistry and by labeling live nerve cells and their processes in tissue culture. The restricted spatio-temporal expression of axonin 1, together with its expression on the surface of neuronal membranes suggests that it is important for the development of sensory projections.

The expression, origin and function of tenascin during peripheral nerve formation in the chick.

During development of the peripheral nervous system, the extracellular matrix molecule tenascin has been found to be closely associated with growing axons. However, its origin and function in peripheral nerve formation are far from clear. In this study, we examined the expression of tenascin during outgrowth of sensory, motor and sympathetic preganglionic axons, and assessed its origin and function in peripheral nerve formation. During outgrowth of sensory and motor axons, a high concentration of tenascin and its mRNA was found to surround sensory and motor axons in the newly formed spinal nerves. The source of this tenascin was examined through a series of surgical manipulations. Neural crest removals did not alter the distribution of tenascin protein or its mRNA surrounding the spinal nerves. Transplantation of quail somites into chick embryos showed that, similar to the distribution of tenascin, there is a high concentration of somitic cells surrounding the spinal nerves. Moreover, somite removals resulted in a reduction of the tenascin and tenascin mRNA surrounding the spinal nerves. Taken together, these results suggest that the majority of the tenascin surrounding the spinal nerves is of somitic origin. Possible functions of tenascin associated with peripheral nerve formation were examined through injections of tenascin or its antiserum into individual somites prior to or during axon outgrowth. Injections of tenascin or its antiserum did not alter the trajectory of peripheral axons in the anterior half of the somite, nor produce gross abnormalities in the morphology of peripheral nerves, suggesting that tenascin does not play a crucial role in the early formation of peripheral nerves.

Effect of ultrasound on axonal outgrowth in the sympathetic nervous system of the chick.

The effects of ultrasound exposure on the rate and specificity of sympathetic preganglionic axonal outgrowth were examined in the chick embryo. Using a technique which allows for exact quantitation of exposure for exact quantiation of exposure conditions, embryos were irradiated in ovo for 5 min daily on 3 consecutive days at an intensity of 1 W/cm2 Spatial Average, Temporal Average (SATA), with a frequency of 1.1 MHz pulsed at 1 kHz and a pulse width of 75 microsecond(s). Our results show no significant difference between irradiated and sham-irradiated embryos. In addition, we have examined the distributions of several major extracellular matrix molecules (fibronectin, laminin and collagen IV) in irradiated and sham-irradiated embryos using immunofluorescent staining. No difference in the staining pattern was found. Finally, we found no increase in the incidence of gross abnormalities and no evidence of lesions and malformations in irradiated embryos.

Ultrasound effects on cell proliferation and migration of chick motoneurons.

The effect of ultrasound exposure on proliferation and migration of motoneurons was examined in chick embryos. Using an egg preparation which minimizes ultrasonic reflections and standing wave generation, chick embryos were exposed to ultrasound in ovo for 10 min at an intensity of 2 W/cm2 Spatial Average, Temporal Average (SATA) with a frequency of 1.1 MHz pulsed at 2 kHz, and a pulse width of 75 microseconds. For cell proliferation studies, embryos were irradiated at the developmental stage of the most active lateral motoneuron proliferation. For cell migration studies, embryos were irradiated at the developmental stage just prior to lateral motoneuron migration. Our results show that the birthdates, migration and proliferation of lateral motoneurons are unaffected by the ultrasound exposure parameters used in this study.

The ECG "lead I sign" in cardiac disease--an indicator of coexisting obstructive pulmonary disease.

Two patients with co-existing cardiac disease and chronic obstructive pulmonary disease are described. The first patient had Wolff-Parkinson-White syndrome and the second patient had extensive anterior Q wave myocardial infarction. In addition to the distinctive ECG patterns of their cardiac abnormalities, both patients also showed the "lead I sign" which is a highly specific marker of chronic obstructive pulmonary disease. These two patients suggest that even in the presence of cardiac disease, the diagnosis of chronic obstructive pulmonary disease should be strongly suspected when the "lead I sign" is present.

Effect of culture media and nutrients on biofilm growth kinetics of laboratory and clinical strains of Enterococcus faecalis.

OBJECTIVE: Enterococcus faecalis is a bacterial pathogen that is often associated with endodontic infections. Biofilm formation is a key virulence attribute in the pathogenicity of E. faecalis. In the present study, we comprehensively examined the effect of various culture media and nutrients on the development of E. faecalis biofilms. DESIGN: A reference strain and a clinical isolate of E. faecalis were used in all experiments for comparison. Commonly used liquid culture media with different nutrient compositions were used to support the development of E. faecalis biofilms in a time-dependent assay. E. faecalis biofilms were quantified by colony forming unit (CFU) and crystal violet (CV) assays. Biofilm architecture and cellular viability were evaluated by scanning electron microscopy and confocal laser scanning microscopy. RESULTS: Growth kinetics evaluated by CFU and CV assays and by microscopy showed that E. faecalis biofilms reached maturity at 72h. "Pg broth" (Tryptic Soy Broth with yeast extract, hemen and vitamin K) promoted E. faecalis biofilm formation more than Brain Heart Infusion broth or Tryptic Soy Broth. Addition of 2% glucose enhanced biofilm formation. Thus, it seems that nutrients such as hemen, vitamin K and glucose are important for E. faecalis for the formation of biofilms. CONCLUSION: The present study demonstrated that nutrient-rich media containing glucose enhances the formation of E. faecalis biofilms, which exhibit maturation at 72h.

Electrocardiography Series. ECGs of structural heart disease: Part 1.

Electrocardiogram (ECG) is a useful but imperfect investigation in the diagnosis and possible follow-up of structural heart disease such as ventricular hypertrophy. Different ECG criteria with different sensitivity and specificity are available to aid the detection of left or right ventricular hypertrophy. Subsequent echocardiography can help in the quantification of ventricular mass and identification of the aetiology.