Preparation and application of an isolated superior mesenteric arterial vascular preparation

Our laboratory developed an isolated perfused superior mesenteric arterial vascular bed preparation to study and correlate vascular smooth-muscle mechanics with associated biochemical events. This preparation provides consistent dose-dependent contractile responses, contains most of the superior mesenteric artery as well as first-, second-, and third-generation arterioles, and has been used for concurrent functional and biochemical analysis of vascular smooth muscle. Preparations isolated from Sprague-Dawley rats produced rapid, dose-related vasoconstrictor responses to norepinephrine (NE) and KCl, while appearing to be unresponsive to periarterial nerve stimulation. Endothelial relaxations to bolus doses of acetylcholine (ACh) in the presence of a constant infusion of NE (10 microM) were limited, producing reductions of perfusion pressures of <25%. Receptor-binding studies conducted to evaluate alpha1-adrenoceptor subtypes revealed high- and low-affinity binding sites composing 91 and 9% of the overall population, respectively. A 60-s time course for contractile response and inositol 1,4,5-triphosphate (IP3) production revealed a significant but transient increase of IP3 that paralleled the contractile response generated by using bolus injections of NE (30 microg). This preparation offers the capacity to conduct perfusion studies investigating vasoconstrictor responses, as well as biochemical studies including receptor-binding and second-messenger assays in the same tissue.

A load-independent in vivo model for evaluating therapeutic interventions in injured myocardium

Although cardiomyocyte damage is normally irreversible, gene therapy and somatic cell transfer offer potential for improving function in damaged regions of the heart. However, in ischemic models of injury, variability in depth, size, and location of damage compromises statistical evaluation of in vivo function. We have adapted cryoablation to create a reproducible, posterior, transmural lesion within rabbit myocardium in which small changes in function are measurable in vivo. Before and at 2 and 6 wk postinjury, in vivo left ventricular intracavitary pressure and myocardial segment length were measured. Regional indexes of performance, segmental stroke work (SW), and percent systolic shortening (SS) were significantly decreased (P < 0.001) postcryoinjury as was the slope (Mw) of the linear preload recruitable SW relationship between SW and end-diastolic segment length (P = 0.0001). Decreased SW, SS, and Mw correlated with wall thinning, loss of myocytes, presence of fibroblasts, and transmural scar formation. Reproducible changes in regional myocardial performance in vivo postcryoinjury suggest that this is a reasonable model for evaluating novel therapies for cardiovascular disease.

Myocardial infarction complicated by ventricular septal rupture in a patient with polycythemia vera and minimal coronary ectasia

Although it is known that patients with polycythemia vera (PV) are at increased risk of myocardial infarction (MI) secondary to thrombosis, ventricular septal rupture in this setting has never been reported. Ventricular septal rupture complicating a small anteroseptal MI is reported in a patient with PV and with only minimal ectasia of the left anterior descending coronary artery. Despite small infarct size these patients may be predisposed to myocardial hemorrhage, increasing the likelihood of myocardial rupture.

Modulation of delta9-tetrahydrocannabinol-induced hypothermia by fluoxetine in the rat

1. It has been suggested that the dose of delta9-tetrahydrocannabinol (delta9-THC) that induces hypothermia in the rat increases the release of brain 5-hydroxytryptamine (5-HT). In light of this, we investigated the hypothermia produced by delta4-THC, and the effect the selective serotonin reuptake inhibitor fluoxetine has on this response. 2. A significant dose-dependent decrease in body temperature occurred after i.v. administration of 0.5 to 5 mg kg(-1) delta9-THC; maximum decreases being 0.8+/-0.2 degrees C to 2.9+/-0.3 degrees C. This hypothermic response was attenuated by the cannabinoid CB1 receptor antagonist SR 141716. 3. Fluoxetine (10 mg kg(-1) i.p.) alone caused a decrease in body temperature of 0.6+/-0.1 degrees C (n=32, P < 0.05) after 40 min. However, pretreatment with fluoxetine (10 mg kg(-1) i.p.) 40 min before delta9-THC significantly reduced the delta9-THC-induced hypothermia (n=7-8, P < 0.05). Contrary to this antagonist-like effect, fluoxetine administered 40 min after delta9-THC significantly potentiated the delta9-THC-induced hypothermia, producing a maximum decrease of 3.2+/-0.3 degrees C. 4. It is suggested that the effect of fluoxetine on the delta9-THC-induced hypothermic response is dependent on the time of its administration relative to that of delta9-THC. Pretreatment with fluoxetine increases extracellular 5-HT due to reuptake inhibition. Increased extracellular 5-HT can activate autoreceptors which may decrease serotonergic activity, thereby reducing the delta9-THC-induced hypothermia. Conversely, when fluoxetine is administered after delta9-THC, the reuptake block is thought to potentiate the already activated serotonergic system, hence potentiating the delta9-THC-induced hypothermia.

Regenerating functional myocardium: improved performance after skeletal myoblast transplantation

The adult heart lacks reserve cardiocytes and cannot regenerate. Therefore, a large acute myocardial infarction often develops into congestive heart failure. To attempt to prevent this progression, we transplanted skeletal myoblasts into cryoinfarcted myocardium of the same rabbits (autologous transfer), monitored cardiac function in vivo for two to six weeks and examined serial sections of the hearts by light and electron microscopy. Islands of different sizes comprising elongated, striated cells that retained characteristics of both skeletal and cardiac cells were found in the cryoinfarct. In rabbits in which myoblasts were incorporated, myocardial performance was improved. The ability to regenerate functioning muscle after autologous myoblast transplantation could have a important effect on patients after acute myocardial infarction.

Allergen-induced early and late asthmatic responses are not affected by inhibition of endogenous nitric oxide

Endogenous exhaled nitric oxide (NO) is increased during the late response to inhaled allergen in patients with asthma and may be bronchoprotective in asthma or have a deleterious effect when generated in excess under inflammatory conditions. To investigate this, we evaluated the effect of inhibiting endogenous NO production with nebulized NG-nitro-L-arginine methyl ester (L-NAME), a nonselective NO synthase (NOS) inhibitor, on early and late asthmatic responses to inhaled allergen in patients with mild allergic asthma. After a screening allergen challenge (AC), 22 male patients attended two visits conducted in a double-blind, randomized, placebo-controlled, crossover manner. Twelve patients demonstrating an early asthmatic response only (single responders) inhaled either L-NAME 170 mg or 0.9% saline 20 min before AC, with exhaled NO and FEV1 measured for 3 h. Ten patients demonstrating both early and late asthmatic responses (dual responders) were studied in a similar fashion but inhaled two further doses of L-NAME or placebo 3.5 and 7 h after the initial dose, with exhaled NO and FEV1 measured for 10 h. L-NAME reduced exhaled NO levels by 77 +/- 5% (p < 0.01) and 71 +/- 7% (p < 0.01) in single and dual responders, respectively, but had no significant effect on early or late asthmatic responses. Following AC in single responders, the mean (+/- SEM) maximum fall in FEV1 after L-NAME and saline was 21.2 +/- 2.9% and 23.8 +/- 3.0%, respectively, and in dual responders, 31.2 +/- 4.5% and 31.8 +/- 5. 8% during the early asthmatic responses, and 27.4 +/- 3.9% and 30.6 +/- 4.5% during the late asthmatic responses, respectively. Area under the curve (AUC) did not significantly differ. AUC0-2 h in single responders after L-NAME and saline was 20.2 +/- 3.9 and 24.9 +/- 4.4 Delta% FEV1/h, and in dual responders, 37.6 +/- 8.4 and 36.7 +/- 8.4 Delta% FEV1/h, respectively, and 106.2 +/- 18.9 and 117.1 +/- 22.4 Delta% FEV1/h, respectively, for the AUC4-10 h. This study suggests that in mild allergic asthma, endogenous NO neither protects against nor contributes to the processes underlying airway responses to inhaled allergen.

Biatrial myxoma: a rare cardiac tumor

A previously healthy 48-year-old man presented to the hospital with a transient ischemic attack. Echocardiography revealed a large left atrial tumor with a second tumor in the right atrium. Surgical excision revealed a large left atrial myxoma with extension through the interatrial septum into the right atrium.

Effect of endogenous nitric oxide inhibition on airway responsiveness to histamine and adenosine-5'-monophosphate in asthma

BACKGROUND

Nitric oxide (NO) may be bronchoprotective in asthma, possibly due to a direct action on airway smooth muscle or through mast cell stabilisation. To investigate this the effects of two doses of nebulised NG-nitro-L-arginine methyl ester (L-NAME), a non-selective NO synthase (NOS) inhibitor, on exhaled NO levels and airway responsiveness to histamine, a direct smooth muscle spasmogen, and adenosine-5'-monophosphate (AMP), an indirect spasmogen which activates mast cells, were evaluated in patients with mild asthma.

METHODS

The study consisted of two phases each with a double blind, randomised, crossover design. In phase 1, 15 subjects inhaled either L-NAME 54 mg or 0.9% saline 30 minutes before histamine challenge. Nine of these subjects were studied in a similar fashion but were also challenged with AMP. In phase 2, 13 subjects (eight from phase 1) performed the same protocol but inhaled L-NAME in a dose of 170 mg or 0.9% saline before being challenged with histamine and AMP.

RESULTS

The mean (95% CI) reduction in exhaled NO levels after L-NAME 54 mg was 78% (66 to 90) but this did not alter airway responsiveness; the geometric mean (SE) concentration provoking a fall of 20% or more in forced expiratory volume in one second (PC20) after L-NAME and saline was 0.59 (1.26) and 0.81 (1.26) mg/ml, respectively, for histamine and 20.2 (1.7) and 17.2 (1.6) mg/ml, respectively, for AMP. In contrast, L-NAME 170 mg reduced NO levels to a similar extent (81% (95% CI 76 to 87)) but increased airway responsiveness by approximately one doubling dose to both spasmogens; the geometric mean (SE) PC20 for histamine after L-NAME 170 mg and saline was 0.82 (1.29) and 1.78 (1.19) mg/ml, respectively (p < 0.001), and for AMP was 11.8 (1.5) and 24.3 (1.4) mg/ml, respectively (p < 0.001).

CONCLUSIONS

These results suggest that L-NAME increases airway responsiveness in asthma. This may occur through mechanisms separate from NO inhibition or through pathways independent of those responsible for production of NO measured in exhaled air.

Induction and maintenance of increased VEGF protein by chronic motor nerve stimulation in skeletal muscle

Vascular endothelial growth factor (VEGF) causes endothelial cell proliferation in vitro and angiogenesis in vivo. Glycolytic skeletal muscles have a lower capillary density than oxidative muscles but can increase their capillary density and convert to a more oxidative phenotype when subject to chronic motor nerve stimulation (CMNS). We used Western analysis and immunohistochemical techniques to examine VEGF protein in a rabbit CMNS model of glycolytic skeletal muscle and in muscles with innate glycolytic versus oxidative phenotypes. VEGF protein per gram of total protein was increased in stimulated vs. control muscles 2.9 +/- 1.0, 3.6 +/- 1.3, 3.1 +/- 0.5, 4.4 +/- 1.6, and 2.7 +/- 0.3 times after 3 (n = 4), 5 (n = 2), 10 (n = 3), 21 (n = 3), and 56 (n = 2) days, respectively. VEGF protein was increased 3.1 +/- 0.5 times (P < 0.005) before (3, 5, and 10 days) and remained elevated 3.7 +/- 1.0 times (P < 0.05) after (21 and 56 days) the transition to an oxidative phenotype. By immunohistochemistry, VEGF protein was found primarily in the matrix between stimulated muscle fibers but not in the myocytes. In addition, VEGF protein was consistently lower in innate glycolytic compared with oxidative muscles. These findings suggest that VEGF plays a role in the alteration and maintenance of vascular density in mammalian skeletal muscles.

Involvement of serotonin in the modulation of cocaine-induced locomotor activity in the rat

The influence of serotonin (5-HT) antagonists and a selective serotonin reuptake inhibitor (SSRI) on cocaine-induced locomotor activity, rears, and head bobs was investigated in female Glaxo Wistar rats. The SSRI, fluoxetine (10 mg/kg), and the nonselective 5-HT agent, methysergide, at the dose range of 5 and 15 mg/kg enhanced the behaviors produced by cocaine (15 mg/kg) to a similar extent. Moreover, the potentiation of cocaine-induced locomotor activity, rears, and head bobs was even greater after the combined administration of methysergide ( 15 mg/kg) and fluoxetine (10 mg/kg). In order to investigate a possible involvement of 5-HT1A receptors in the observed potentiation by methysergide and fluoxetine, the potent and selective 5-HT1A antagonist, WAY 100635, was used. WAY 100635 (0.1 and 1.5 mg/kg) markedly reduced the behaviors induced by cocaine preceded by fluoxetine (10 mg/kg) and methysergide (5 and 15 mg/kg) pretreatment, respectively, suggesting an involvement of 5-HT1A receptors in the action of fluoxetine and methysergide on cocaine-induced behaviors. An attenuation of the fluoxetine-enhanced cocaine-induced behaviors was also observed after pretreatment with the 5-HT2A antagonist ketanserin (0.1 and 1.0 mg/kg). Coadministration of ketanserin (1.0 mg/kg) and WAY 100635 (1.5 mg/kg) resulted in the greatest blockade of the fluoxetine-enhanced cocaine-induced behaviors. The antagonists and the SSRI, fluoxetine, did not alter the behaviors in comparison to that of saline-treated animals. These results provide evidence for an involvement of 5-HT1A receptors in the enhancing effect of fluoxetine and methysergide on cocaine-induced locomotor activity, rears, and head bobs, and suggest a stimulatory action of methysergide at the 5-HT1A receptor. In addition, some of the actions may also be mediated by activation of the 5-HT2A receptor and/or inhibition of the 5-HT2C receptor.

Regulation of carbohydrate and fatty acid utilization by L-carnitine during cardiac development and hypoxia

This study is designed to investigate whether substrate preference in the myocardium during the neonatal period and hypoxia-induced stress is controlled intracellularly or by extracellular substrate availability. To determine this, the effect of exogenous L-carnitine on the regulation of carbohydrate and fatty acid metabolism was determined during cardiac stress (hypoxia) and during the postnatal period. The effect of L-carnitine on long chain (palmitate) and medium chain (octonoate) fatty acid oxidation was studied in cardiac myocytes isolated from less than 24 h old (new born; NB), 2 week old (2 week) and hypoxic 4 week old (HY) piglets. Palmitate oxidation was severely decreased in NB cells compared to those from 2 week animals (0.456+/-0.04 vs. 1.207+/-0.52 nmol/mg protein/30 min); surprisingly, cells from even older hypoxic animals appeared shifted toward the new born state (0.695+/-0.038 nmol/mg protein/30 min). Addition of L-carnitine to the incubation medium, which stimulates carnitine palmitoyl-transferase I (CPTI) accelerated palmitate oxidation 3 fold in NB and approximately 2 fold in HY and 2 week cells. In contrast, octanoate oxidation which was greater in new born myocytes than in 2 week cells, was decreased by L-carnitine suggesting a compensatory response. Furthermore, oxidation of carbohydrates (glucose, pyruvate, and lactate) was greatly increased in new born myocytes compared to 2 week and HY cells and was accompanied by a parallel increase in pyruvate dehydrogenase (PDH) activity. The concentration of malonyl-CoA, a potent inhibitor of CPTI was significantly higher in new born heart than at 2 weeks. These metabolic data taken together suggest that intracellular metabolic signals interact to shift from carbohydrate to fatty acid utilization during development of the myocardium. The decreased oxidation of palmitate in NB hearts probably reflects decreased intracellular L-carnitine and increased malonyl-CoA concentrations. Interestingly, these data further suggest that the cells remain compliant so that under stressful conditions, such as hypoxia, they can revert toward the neonatal state of increased glucose utilization.

Multicenter masked evaluation of AutoCyte PREP thin layers with matched conventional smears. Including initial biopsy results

OBJECTIVE

To compare the performance of liquid-based cell preparations from the AutoCyte PREP system (AutoCyte, Inc., Elon College, North Carolina) with the conventional cervical smear in masked, split-sample, multisite trials.

STUDY DESIGN

The AutoCyte PREP system utilizes the CytoRich method, which combines liquid preservation, selective reduction of blood and inflammation, thin-layer cell dispersion and discrete staining. In an eight-site multicenter trial, 8,983 cases were evaluated. Parallel AutoCyte PREP slides and matching conventional cervical cytologic smears were screened in a masked fashion, with all abnormals reviewed in a masked, on-site pathologist review. The conventional smear was always prepared first, with the AutoCyte PREP using the residual cells on the collection device. The Bethesda System was used for reporting diagnosis and specimen adequacy.

RESULTS

Of the cases, 7,805 (86.9%) had the same interpretation. In 8,750 cases (97.4%), there was agreement within one diagnostic category. The AutoCyte PREP demonstrated a statistically significant, 31% overall improvement in the detection of squamous intraepithelial lesion and invasive cancer when evaluating cases with more than one diagnostic class difference. Biopsy correlation of available data supported the improvement observed in the cytology-based comparison. Recovery of infectious organisms and endocervical component was comparable between preparations, especially in light of the split-sample study design. There was a 39% reduction in unsatisfactory slides and 44% fewer satisfactory but limited by reports.

CONCLUSION

The AutoCyte PREP and CytoRich method produce excellent cellular presentations with standardized quality, superior sensitivity and improved adequacy as compared to the conventional method.

Comparison of salmeterol and albuterol-induced bronchoprotection against adenosine monophosphate and histamine in mild asthma

Short-acting beta(2)-agonists provide greater protection to bronchoconstriction induced by adenosine-5'-monophosphate (AMP) than does methacholine. Because AMP produces bronchoconstriction through release of mediators from mast cells, and methacholine directly constricts airway smooth muscle, this suggests that beta(2)-agonists stabilize mast cells in vivo. This in vivo property has not been demonstrated with long-acting beta(2)-agonists. We undertook two double-blind, randomized, crossover, placebo-controlled studies to investigate the effects of salmeterol and albuterol on airway responsiveness (AR) to AMP and histamine in patients with mild asthma. In the first study, 19 patients attended on four occasions to inhale salmeterol 50 micrograms or placebo 2 h before challenge with AMP or histamine. In the second study 16 patients (13 of whom had participated in the first study) were studied in a similar fashion but inhaled albuterol 400 micrograms or placebo 30 min prior to challenge. Salmeterol reduced AR to AMP and histamine by 3.4 +/- 0.3 and 3.9 +/- 0.3 doubling doses, respectively (NS). In contrast, albuterol demonstrated a greater protective effect on AMP than on histamine, reducing AR by 5.1 +/- 0.3 and 3.8 +/- 0.2 doubling doses, respectively (p < 0.005). Thus, in contrast to albuterol, salmeterol did not demonstrate mast-cell stabilizing properties in vivo at a time corresponding to maximal bronchodilatation. These findings might be explained by the unique pharmacologic profile of salmeterol in combination with the differential beta(2)-adrenoceptor pharmacology of bronchial mast cells and bronchial smooth muscle.

A comparison of low-dose inhaled budesonide plus theophylline and high-dose inhaled budesonide for moderate asthma

BACKGROUND

Inhaled glucosteroids and oral theophylline are widely used to treat asthma. We compared the benefits of adding theophylline to inhaled glucosteroid with those of doubling the dose of inhaled glucosteroid in patients with persistent symptoms despite the use of inhaled glucosteroid.

METHODS

In a double-blind, placebo-controlled trial, we randomly assigned 62 patients to receive either 400 microg of inhaled budesonide (low-dose budesonide) with 250 or 375 mg of theophylline (depending on body weight) or 800 microg of inhaled budesonide (high-dose budesonide). All doses were given twice daily for three months. Lung function was measured serially, and patients kept records of peak expiratory flow, symptoms, and albuterol use. The effects of treatment on endogenous cortisol levels were also assessed.

RESULTS

Both treatments resulted in improvements in lung function that were sustained throughout the study. As compared with treatment with high-dose budesonide, treatment with low-dose budesonide plus theophylline resulted in greater improvements in forced vital capacity (P=0.03) and forced expiratory volume in one second (P= 0.03). There were significant and similar reductions in beta2-agonist use and the variability of peak expiratory flow, a correlate of bronchial hyperresponsiveness and the severity of asthma. Serum cortisol concentrations were significantly reduced in the group given high-dose budesonide (from a mean [+/-SE] of 18.4+/-2.4 microg per deciliter to 15.9+/-2.1 microg per deciliter, P=0.02) but were unchanged in the other group. The median serum theophylline concentration was 8.7 microg per milliliter (therapeutic range, 10 to 20) among those who received theophylline. Both treatments were well tolerated.

CONCLUSIONS

For patients with moderate asthma and persistent symptoms, low-dose inhaled budesonide with theophylline and high-dose inhaled budesonide produced similar benefits. Effects were achieved at theophylline concentrations below the recommended therapeutic range. The addition of low-dose theophylline to inhaled glucosteroid may be preferable to and cheaper than increasing the dose of inhaled glucosteroid.

Reduced effects of L-carnitine on glucose and fatty acid metabolism in myocytes isolated from diabetic rats

Depressed glucose utilization and over-reliance of muscle tissues on fat represents a major metabolic disturbance in diabetes. This study was designed to investigate the relationship between fatty acid oxidation and glucose utilization in diabetic hearts and to examine the role of L-Carnitine on the utilization of these substrates in diabetes. 14CO2 release from [1-14C]pyruvate (an index of PDH activity), [2-14C]pyruvate and [6-14C]glucose (an index of acetyl-CoA flux through the Krebs cycle), [U-14C]glucose (an index of both PDH and acetyl-CoA flux through the Krebs cycle), and [1-14C]palmitate oxidation were studied in cardiac myocystes isolated from normal and streptozotocin-injected rats. Palmitate oxidation was increased twofold in diabetic myocytes compared to normal cells (5.4 +/- 1.45 vs 2.35 +/- 0.055 nmol/mg protein/30 min, p > 0.05). L-Carnitine (5 mM) significantly increased palmitate oxidation (60-70%) in normal cells but had no effect on diabetic cells. The activity of PDH and acetyl-CoA flux through the Krebs cycle was severely depressed in diabetes (58.14 +/- 20.27 and 8.63 +/- 0.62 in diabetes vs 128.75 +/- 11.47 and 24.84 +/- 7.81 nmol/mg protein/30 min in controls, p > 0.05, respectively). The efflux of acetylcarnitine, a by-product of PDH activity was also much lower in diabetic cells than in normal cells but had no effect in diabetes. L-Carnitine also had no effect on 14CO2 release from [U-14C]glucose but significantly decreased that from [6-14C]glucose, which reflects oxidative metabolism suggesting that L-Carnitine decreases oxidative glucose utilization. Thus, these data suggest that the overreliance on fat in diabetes may be in part secondary to a reduction of carbohydrate-generated acetyl-CoA through the Krebs cycle.

Examination by radioligand binding of the alpha1 adrenoceptors in the mesenteric arterial vasculature during the development of salt-sensitive hypertension

Previous experiments have suggested that the vascular smooth muscle of Dahl salt-sensitive (DS) rats may possess a difference in the alpha1-adrenoceptor population or its transduction processes compared to Dahl salt-resistant (DR) rats. The purpose of the current research is to study the role of alpha1-adrenoceptors in the specific supersensitivity to norepinephrine (NE) seen prior to and early in the development of hypertension in the DS rat. Experiments in isolated perfused superior mesenteric arterial vasculature from DS rats chronically fed a high (7%) salt diet for 5 days or 3 weeks, in the absence or presence of an elevation in systolic blood pressure, respectively, demonstrated a specific supersensitivity to NE relative to DR rats. The enhanced responsiveness was specific to NE after 5 days of high salt since no differences in sensitivity of these preparations was observed to either KCl or 5-HT. A small but significant elevation in sensitivity to KCl following 3 weeks of treatment suggests that multiple factors may contribute to tissue responsiveness at this time. Radioligand binding experiments were performed using [125I]-HEAT to study the alpha1-adrenoceptor population and its subtypes. Saturation experiments using membranes prepared from the superior mesenteric arterial vasculature or mesenteric arterial branches showed no significant differences in overall alpha1-adrenoceptor population between DS and DR rats fed a high-salt diet for 5 days or 3 weeks. Competition experiments using membranes prepared from the superior mesenteric arterial branches in the presence of the alpha1A-subtype selective antagonist 5-methylurapidil showed two binding sites (high and low affinity) in these resistance vessels but no significant differences in nature or ratio of these sites between the DS and DR groups. These results suggest that changes in the alpha1-adrenoceptor population are not responsible for the specific supersensitivity to NE, which may be an early event in the induction and development of hypertension.

Adult patients' knowledge about their congenital heart disease

OBJECTIVE

To assess patient knowledge about their congenital cardiovascular disease.

DESIGN

Fifty consecutive patients (25 women) attending the Adult Congenital Heart Disease Clinic, University of Alberta, Edmonton, Alberta, filled out a questionnaire that tested knowledge about their heart defect and endocarditis prophylaxis. The patients ranged in age from 18 to 60 years (mean 25). The most frequent cardiovascular anomalies were obstruction of the left ventricular outflow tract (13), coarctation of the aorta (10), tetralogy of Fallot (six), transposition of the great arteries (five) and Marfan syndrome (four). Patients had been seen on average by three cardiologists (range one to six) and had made an average of seven clinic visits (range one to 22) since the age of 17 years. Eight patients had been followed at other clinics in the past.

MAIN RESULTS

Fifty-four per cent of patients knew their diagnosis. Forty-four per cent could explain the defect in lay language, and another 48% made an attempt. When given a heart diagram, 26% marked their defect correctly and 28% made an attempt. Terms 'endocarditis' and 'antibiotic prophylaxis' were known to 16% and 22% of patients, respectively. Fifty-eight per cent could name at least one situation that carries a risk of 'infection in the heart'.

CONCLUSION

Adults with congenital heart disease have poor knowledge of their heart defects and the importance of endocarditis and antibiotic prophylaxis. Although time consuming, patient education should be a part of every clinic visit. Repetitive and structured patient education may improve patients' knowledge and, hence, participation in their health care.

Calretinin expression in the chick brainstem auditory nuclei develops and is maintained independently of cochlear nerve input

The expression of the calcium-binding protein calretinin (CR) in the chick brainstem auditory nuclei angularis (NA), laminaris (NL), and magnocelularis (NM) was studied during normal development and after deafening by surgical removal of the otocyst (embryonic precursor of the inner ear) or columella (middle ear ossicle). CR mRNA was localized by in situ hybridization by using a radiolabeled oligonucleotide chick CR probe. CR immunoreactivity (CR-IR) was localized on adjacent tissue sections. CR mRNA signal in the auditory nuclei was expressed at comparable levels at embryonic day (E)9 and E11 and increased thereafter to reach the highest levels in posthatch chicks. CR-IR neurons were apparent in NM and NA at E11 and in NL by E13, and CR-IR increased in all three auditory nuclei thereafter. Neither unilateral nor bilateral otocyst removal caused detectable changes in the intensity of CR mRNA expression or CR-IR in the auditory nuclei at any of the several ages examined. Similarly, columella removal at posthatching day 2 or 3 failed to significantly affect CR mRNA or CR-IR levels at 3 hours, 1 day, or 3-4 days survival times. We conclude that cochlear nerve input is not necessary for expression of either calretinin mRNA or protein and that the profound decrease in sound-evoked activity caused by columella removal does not affect the maintenance of CR expression after hatching.

Optimal dose and duration of heparin for inhibition of intimal hyperplasia

BACKGROUND

A Dacron patch graft was placed in the common carotid artery of sheep to assess the effect of three different doses of unfractionated heparin administered for periods of one to four weeks.

MATERIALS AND METHODS

Animals were divided into a control group (n=6) in which animals received a patch graft but no heparin and three main treatment groups on the basis of the dose of heparin received. Group 1 animals (n=24) received 140 units per kg daily in two divided doses. Group 2 (n=24) received 280 units per kg daily and Group 3 (n=24) received 420 units per kg daily. Each treatment group was further divided into four subgroups on the basis of the duration of treatment. Groups 1(i), 2(i), 3(i) had treatment for one week. Groups 1(ii), 2(ii), 3(ii) had treatment for two weeks. Groups 1(iii), 2(iii), 3(iii) had treatment for three weeks. Groups 1(iv), 2(iv), 3(iv) had treatment for four weeks. There were six animals in each subgroup giving a total of 72 treated sheep. Animals were sacrificed at four weeks and an intimal measurement in pm was obtained under light microscopy from a transverse sectioned segment of artery containing the patch graft using an eyepiece graticule.

RESULTS

There were no haemorrhagic complications. Control animals had a mean intimal thickness of 176 pm. All treatment groups had significantly less IH--Group 1 131.9 (p<0.01), Group 2 138.5 (p<0.05), Group 3 117.8 (p<0.01). There were no significant differences between the treatment groups. There was significantly less IH in animals treated for four weeks (106.3) compared to one week (140.2, p<0.05).

CONCLUSIONS

This study indicates that inhibition of IH can be achieved by heparin with optimal effect from a four week treatment period.

The structure of a calmodulin mutant with a deletion in the central helix: implications for molecular recognition and protein binding

BACKGROUND

Calmodulin (CaM) is the major calcium-dependent regulator of a large variety of important intracellular processes in eukaryotes. The structure of CaM consists of two globular calcium-binding domains joined by a central 28-residue alpha helix. This linker helix has been hypothesized to act as a flexible tether and is crucial for the binding and activation of numerous target proteins. Although the way in which alterations of the central helix modulate the molecular recognition mechanism is not known exactly, the relative orientation of the globular domains seems to be of great importance. The structural analysis of central helix mutants may contribute to a better understanding of how changes in the conformation of CaM effect its function.

RESULTS

We have determined the crystal structure of a calcium-saturated mutant of chicken CaM (mut-2) that lacks two residues in the central helix, Thr79 and Asp80, at 1.8 A resolution. The mutated shorter central helix is straight, relative to that of the wild-type structure. The loss of a partial turn of the central alpha helix causes the C-terminal domain to rotate 220 degrees around the helix axis, with respect to the N-terminal domain. This rotation places the two domains on the same side of the central helix, in a cis orientation, rather than in the trans orientation found in wild-type structures.

CONCLUSIONS

The deletion of two residues in the central helix of CaM does not distort or cause a bending of the linker alpha helix. The main consequence of the mutation is a change in the relative orientation of the two globular calcium-binding domains, causing the hydrophobic patches in these domains to be closer and much less accessible to interact with the target enzymes. This may explain why this mutant of CaM shows a marked decrease in its ability to activate some enzymes while the mutation has little or no effect on its ability to activate others.

Delivery of primary autologous skeletal myoblasts into rabbit heart by coronary infusion: a potential approach to myocardial repair

Myocardial repair after injury is limited because the adult heart cannot regenerate. We propose using autologous skeletal muscle cells (myoblasts) as a source of reserve cells for repair of regions of damaged myocardium. This report examines two potential methods for the transfer of cells to the myocardium: selective coronary catheterization, and myoblast infusion or myoblast injection directly into the left ventricular wall. Autologous, primary rabbit skeletal myoblasts were harvested, were transduced ex vivo with adenoviruses expressing the Escherichia coli beta-galactosidase (beta-gal) gene, and were infused selectively into the coronary circulation or injected directly into the myocardial wall. After either delivery method, beta-gal expression was detectable at the earliest times examined (3 days) and persisted for several weeks. The method of delivery influenced the spatial pattern of beta-gal expression. After direct injection, a localized concentration of myoblasts that decreased with distance from the injection site was visible primarily in the myocardial layer of the ventricle, although occasional staining could be detected in other layers. After coronary infusion, discrete punctate or linear foci of beta-gal expression were found throughout the distribution of the left coronary circulation in all cardiac layers. After infusion or injection, beta-gal-positive cells were seen in direct physical apposition to cardiocytes; interestingly, beta-gal could be detected also in some branched cells with clear cross-striations. Autologous myoblasts survived with no obvious dysrhythmic effects despite their presence in extensive or discrete loci in the myocardium. These observations provide the first evidence that myoblast transfer is possible by catheter-based methods, and they create the basis for studies to investigate the functional consequences of myoblast infusion in damaged heart.

Involvement of mu- and delta-opioid receptors in the effects of systemic and locally perfused morphine on extracellular levels of dopamine, DOPAC and HVA in the nucleus accumbens of the halothane-anaesthetized rat

The effects of systemic and intra-accumbens infusion of morphine on the extracellular level of dopamine (DA) and its metabolites, DOPAC and HVA, were investigated in the nucleus accumbens (NAcc) of halothane-anaesthetized rats using in vivo microdialysis. Morphine in a dose of 1 or 5 mg/kg i.v. produced a significant increase (60-100% of baseline levels) in the extracellular level of DA for at least 3 h. Morphine at 5, but not 1 mg/kg, produced a small (10-15%) but significant reduction in the level of DOPAC when compared with saline in the first h following injection. Pretreatment with the preferential mu-opioid receptor antagonist naloxone in a dose of 1 or 3 mg/kg i.p. significantly blocked the morphine-induced changes in the extracellular levels of DA and DOPAC. Pretreatment with the selective delta-opioid receptor antagonist, naltrindole, at 1 mg/kg i.p. blocked only the morphine-induced decrease in DA metabolism. Furthermore, in the presence of naltrindole, systemic morphine induced a large and long-lasting increase in the level of DOPAC and HVA, which was significantly higher than in rats receiving combinations of saline/water + saline, saline/water + morphine and naltrindole + saline. When applied directly into the NAcc, morphine at concentrations of 125, 250 and 500 ng infused over 10 min produced a dose-related increase in the extracellular level of accumbens DA with either no effect or a small reduction in the level of DOPAC and HVA. The effects of intra-accumbens morphine on DA levels were significantly blocked by pretreatment with i.p. naltrindole but not naloxone. These results indicate that, while systemic morphine probably increases DA via activation of mu-opioid receptors, local perfusion of morphine increases DA in the NAcc via activation of delta-opioid receptors located in the NAcc. Furthermore, under the conditions of the study, it appears that activation of mu- and delta-opioid receptors by morphine respectively increases and decreases DA metabolism.

Quantitative relation of electrocardiographic and angiocardiographic measures of risk in patients with coronary atherosclerosis. Simvastatin/Enalapril Coronary Atherosclerosis Trial (SCAT) Investigators

OBJECTIVE

To correlate angiocardiographic and electrocardiographic (ECG) measures of risk in coronary artery disease (CAD) patients.

SETTING

Baseline substudy of the Simvastatin/Enalapril Coronary Atherosclerosis Trial (SCAT), a 2 x 2 factorial, randomized, controlled trial of CAD regression.

PATIENTS

One hundred and twenty-three CAD patients, 113 males and 10 females; average age, 59 years.

METHODS

Bivariate correlations of multiple quantitative measures of epicardial coronary angiographic luminal narrowing (quantitative coronary angiography [QCA]) and body surface ECG maps of the sum of the decrease in the potential time integral of the ST segment (SST decrease) between rest and symptom-limited exercise and between rest and 1 and 5 mins postexercise recovery.

RESULTS

The average number of epicardial coronary segments analyzed per patient was 12. The mean diameter averaged 2.78 mm; the minimal diameter, 2.01 mm. The mean percentage coronary stenosis averaged 29.6% and the most severe averaged 62.9%. sigma ST decrease averaged -5323 microV.s between rest and peak exercise and recovered slowly, averaging -5117 microV.s at 1 min postexercise and -4562 microV.s at 5 mins. No QCA measure correlated with any ECG variable (range of r, 0.002 to -0.179; not significant).

CONCLUSIONS

Among CAD patients there are no close, or causal, relations between angiographic measures of anatomic epicardial coronary atherosclerosis and ECG functional measures of exercise-induced myocardial ischemia. These data suggest that demonstrated values of stress ECG and coronary angiography for the prediction of clinical risk in CAD patients are largely independent of each other.

Hyperpolarizing effects of morphine, clonidine and 2-chloroadenosine in myenteric neurons associated with tolerance to morphine

Chronic treatment of guinea pigs with morphine produces non-specific subsensitivity (tolerance) of the longitudinal smooth muscle myenteric plexus (LM/MP) preparation of the guinea pig ileum to morphine, clonidine and 2-chloroadenosine correlated with a partial depolarization of myenteric S neurons. The purpose of our investigation was to gain further evidence regarding the cellular mechanism of tolerance. Either morphine or placebo pellets were implanted s.c. in guinea pigs 7 days before the experiment. Subsensitivity was confirmed by a marked decrease of the inhibitory effect of 0.1 microM morphine and 0.3 microM clonidine on neurogenically induced twitches in longitudinal smooth muscle myenteric plexus preparations from the morphine-pretreated guinea pigs. Intracellular microelectrode recording established that only myenteric S neurons that were hyperpolarized by morphine exhibited the depolarized state (difference of 7.2 mV), which occurred without a change in the threshold for initiation of action potentials. S neurons that were hyperpolarized by superfusion with solution containing morphine, 0.1 microM, were acutely hyperpolarized an equivalent amount (6-8 mV) by clonidine, 0.3 microM, or 2-chloroadenosine, 0.1 microM. Morphine and clonidine, but not 2-chloroadenosine, reduced input resistance. The hyperpolarizations and changes in conductance were not different between tolerant and control preparations for any agonist. It is concluded that 1) the receptors for the three agonists are colocalized on selected S neurons, 2) the transduction process for the hyperpolarizing effect of 2-chloroadenosine is different than that for morphine and clonidine, 3) cross-tolerance among the agonists is not a function of altered receptors or signal transduction processes and 4) the depolarized state is associated with tolerance of myenteric S neurons.

Mechanisms of adaptive supersensitivity: correlation of guinea pig atrial supersensitivity with modifications in adenylyl cyclase activity

The possibility that the cellular mechanism underlying adaptive supersensitivity in right and left atria of the guinea pig may involve either adenylyl cyclase or components of that transduction process was examined in left and right atria obtained from controls or guinea pigs chronically treated with reserpine. Adenylyl cyclase activity and the abundance of alpha-subunits of several G-proteins (i.e. Gs, Gi, and Go) were quantified using standard techniques. Functional concentrations of Gs and Gi were compared in tissues from control and treated animals using pertussis- or cholera toxin-induced protein ribosylation. Chronic treatment with reserpine did not alter basal levels of adenylyl cyclase activity in left or right atrium but did increase significantly the ability of isoproterenol, 5'-guanylylimido diphosphate, and forskolin to activate adenylyl cyclase in the left atrium compared with the control. In contrast, treatment with reserpine increased the ability of only isoproterenol to active adenylyl cyclase in the right atrium. The increases in enzyme activation were not correlated with any detectable change in the concentrations of G-proteins or beta-adrenoceptors. The correlation between the specificity of changes in responsiveness and increased activation of adenylyl cyclase suggests that the cellular mechanism that underlies the development of adaptive supersensitivity in the guinea pig myocardium may involve a modification of adenylyl cyclase. The data also support the idea that the development of enhanced responsiveness in cardiac muscle may not only involve more than one cellular mechanism but may even differ between right and left atrium and ventricles of the same species.