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Biomedical subjects

T J Kulik

Publications and source records attributed to T J Kulik.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effect of stretch on growth and collagen synthesis in cultured rat and lamb pulmonary arterial smooth muscle cells.

There are no studies of the effect of stretch in cultured pulmonary vascular smooth muscle, and some data suggest that a stretch-mediated increase in connective tissue synthesis in pulmonary arteries is mediated by the endothelium. To investigate whether stretch can serve as a growth stimulus in this smooth muscle, we studied two types of cultured pulmonary arterial smooth muscle cells (a multiply passaged clonal line of rat cells [PAC1], and early passage lamb cells [EPTC]). Cells were grown on a collagen-coated silicone surface and subjected to repetitive stretch (0.33-0.5 Hz; 10-20% strain). The relative rates of total RNA, DNA, protein, and soluble collagen synthesis were determined using 3H precursors, and c-fos and collagen mRNAs by Northern blot analysis. Stretch caused no significant change in the rate of RNA synthesis in either PAC1 cells (+9%) or EPTC (-3%). The relative rate of total protein synthesis was decreased by stretch (6% in PAC1 cells and 36% in EPTC [both NS]) as was the rate of collagen synthesis (-24% in EPTC [NS]). In EPTC, the percentage of 3H-thymidine labeled cells was modestly increased with 24 h stretch (17 +/- 5.7%; P < .001), but trichloroacetic acid (TCA) precipitated 3H-thymidine was unaltered by stretch, and the number of cells not significantly changed with stretch. c-fos mRNA expression was only inconsistently induced by stretch x 30 min in EPTC, and not at all in PAC1 cells. Expression of mRNA for alpha 1 (I) and alpha 1 (III) collagen was not changed significantly by 24 h or 48 h of stretch. We conclude that stretch does not serve as a significant growth stimulus in cultured pulmonary vascular smooth muscle cells in this system. These findings do not rule out the possibility that stretch is a growth stimulus for these cells under different conditions, but do suggest that other models will be needed to determine if and how mechanical stimuli affect growth of pulmonary vascular smooth muscle.

Animals↗
PubMed1993

Real-time gas-exchange measurement of oxygen consumption in neonates and infants after cardiac surgery.

OBJECTIVES: The purposes of this study were: a) to measure oxygen consumption (VO2) in ventilated neonates and infants after cardiac surgery, utilizing a real-time gas exchange system; and b) to assess this new method by comparing the measured VO2 with calculated VO2 (using the Fick equation and simultaneously determined thermodilution cardiac output, measured hemoglobin, and measured mixed venous and arterial saturations). DESIGN: Prospective, comparison study. Comparison of measured VO2 and calculated VO2 using correlation coefficient, linear regression analysis, and bias and precision. SETTING: Cardiac intensive care unit in a children's hospital. PATIENTS: A total of 60 direct comparisons were made between measured and calculated VO2 in 15 patients (ages ranging from 4 days to 14.1 months with median age of 2.4 months) who were receiving mechanical ventilation after undergoing corrective cardiac surgery. INTERVENTIONS: a) Direct measurement of VO2 using gas exchange method involving a pneumotachograph and a gas sampling system; b) determination of cardiac output by the thermodilution technique; c) measurement of arterial and mixed venous oxygen content by blood sampling. MEASUREMENTS AND RESULTS: The absolute measured VO2 ranged from 19 to 154 mL/min with a mean of 52 +/- 32 mL/min (when indexed, the range was 81 to 367 mL/min/m2 with mean 185 +/- 69 mL/min/m2, or range 4.7 to 18.8 mL/min/kg with mean 10.4 +/- 3.3 mL/min/kg). While 34 (57%) of 60 measured VO2 values were within 10% of their respective calculated VO2 values, 58 (97%) of 60 were within 25%; the mean percent difference between measured and calculated VO2 values was 10.6 +/- 7.7%. In comparing the measured VO2 and calculated VO2, the correlation coefficient was good (r2 = .87; p < .01) and the linear regression equation was: measured VO2 = 1.1 x calculated VO2 -9.0 mL/min/m2. The mean difference, or bias, was 0 mL/min/m2 with precision of 26 and 52 mL/min/m2 (at 1 and 2 SD). As an alternative means of examining the measured VO2 data, we also directly compared the thermodilution cardiac output with cardiac output derived by using the measured VO2 and the Fick equation. The range of Fick-derived cardiac output was between 1.69 to 8.11 L/min/m2 (mean 3.72 +/- 1.56) and the range of thermodilution cardiac output was between 1.75 to 7.42 L/min/m2 (mean 3.71 +/- 1.36). The correlation coefficient between thermodilution cardiac output and Fick-derived cardiac output was good with r2 = .88 (p < .01) and the linear regression equation was: thermodilution cardiac output = 0.81 x Fick-derived cardiac output + 0.71 L/min/m2. The bias was -0.01 L/min/m2 with a precision of 0.54 L/min/m2 at 1 SD (or 1.08 L/min/m2 for 2 SD). CONCLUSIONS: Measured VO2 using a gas-exchange system compared favorably with calculated VO2 values using the Fick equation and simultaneously obtained thermodilution cardiac output and arterial and venous oxygen concentrations. By employing this breath-by-breath gas-exchange system, real-time VO2 measurement in ventilated neonates and infants is now feasible.

Bias↗
PubMed1993

Use of inhaled nitric oxide and acetylcholine in the evaluation of pulmonary hypertension and endothelial function after cardiopulmonary bypass.

BACKGROUND: Increased pulmonary vascular resistance is common in congenital heart disease and is exacerbated by cardiopulmonary bypass (CPB). We investigated whether CPB is responsible for pulmonary endothelial dysfunction and contributes to postoperative pulmonary hypertension. METHODS AND RESULTS: We infused the endothelium-dependent vasodilator acetylcholine (ACH) into the pulmonary circulation of pulmonary hypertensive children with congenital heart disease either before (n = 12) or after (n = 22) surgical repair on CPB. The dose response to ACH (10(-9) to 10(-6) M) was recorded for all hemodynamic variables. Nine additional postoperative patients were studied with ACH followed by inhalation of 80 ppm nitric oxide, an endothelium-independent smooth muscle relaxant. Plasma levels of cyclic GMP (cGMP) were measured before and after ACH and nitric oxide administration. Pulmonary vasodilation with 10(-6) M ACH was seen in all preoperative patients but was markedly attenuated in postoperative patients. Baseline pulmonary vascular resistance (5.6 +/- 1.0 U x m2) fell 46 +/- 5% in preoperative patients but declined only 11 +/- 4% from baseline (5.8 +/- 0.9 U x m2) in postoperative patients (P < .002). However, inhalation of 80 ppm nitric oxide after ACH infusion in postoperative patients lowered pulmonary vascular resistance by 33 +/- 4% (P < .0002 compared with postoperative ACH response) with minimal effects on the systemic circulation. This finding suggests that the capacity for smooth muscle relaxation and pulmonary vasodilation was present in postoperative patients but could not be induced by ACH. Plasma levels of cGMP in postoperative patients were unchanged after acetylcholine infusion but rose more than threefold during pulmonary vasodilation with nitric oxide (P < .0001). This finding is consistent with the purported role of cGMP as the second messenger effecting smooth muscle relaxation in this process. CONCLUSIONS: CPB may be responsible for postoperative dysfunction of the pulmonary endothelial cell and may contribute to postoperative pulmonary hypertension in children. Inhaled nitric oxide is a potent pulmonary vasodilator after CPB with minimal systemic circulatory effects. It may have important diagnostic and therapeutic applications in patients with congenital heart disease.

Acetylcholine↗
PubMed1993

Correction of total anomalous pulmonary venous connection in infancy.

From January 1985 through January 1993, 41 patients less than 1 year of age underwent operative correction of isolated total anomalous pulmonary venous connection. There were 24 boys and 17 girls. The median age at operation was 13 days (range 1 to 282 days) and weight was 3.6 kg (2.5 to 5.2 kg). Locations of the connections were supracardiac in 19, cardiac in 9, infracardiac in 11, and mixed supracardiac and cardiac in 2. Obstruction of the pulmonary veins was severe in 24, mild in 3, and absent in 14. Preoperative stabilization included mechanical ventilation for 15 patients for a mean duration of 2 1/2 days and extracorporeal membrane oxygenation for 1 patient for 1 day. All operations were performed with deep hypothermia and circulatory arrest (mean arrest time 34 minutes). Supracardiac connections were repaired by performing a side-to-side anastomosis between the pulmonary venous confluence and the dome of the left atrium through a superior approach between the superior vena cava and the aorta. Coronary sinus connections were repaired by enlarging the atrial septal defect and the coronary sinus communication with the left atrium and closing the atrial defect with a large patch. Infracardiac repairs included elevation and rotation of the heart to the right and an elongated side-to-side anastomosis between the common venous confluence and the left atrium. One patient died 1 week postoperatively of persistent pulmonary hypertension. Another patient, who was supported by extracorporeal membrane oxygenation before the operation, died 3 months after the operation as a consequence of pulmonary lymphangiectasia. All other patients are alive and well with a mean follow-up of 26 months (range 3 to 77 months). One patient required two subsequent reoperations for persistent pulmonary venous obstruction, and another patient had superior vena cava obstruction necessitating reoperation. Operative treatment of total anomalous pulmonary venous connection in infants can be performed with low mortality and an infrequent need for reoperations.

Cardiac Surgical Procedures↗
PubMed1992

Molecular characterization of the stretch-induced adaptation of cultured cardiac cells. An in vitro model of load-induced cardiac hypertrophy.

Although it is a well-known fact that hemodynamic load is a major determinant of cardiac muscle mass and its phenotype, little is known as to how mechanical load is converted into intracellular signals of gene regulation. To address this question, we characterized the stretch-induced adaptation of cultured neonatal cardiocytes grown on a stretchable substrate in a serum-free medium. Static stretch (20%) of the cells was applied without cell injury. Stretch caused hypertrophy in myocytes and hyperplasia in non-myocytes. Stretch caused an induction of immediate-early genes such as c-fos, c-jun, c-myc, JE, and Egr-1, but not Hsp70. Immunostaining showed that the stretch-induced Fos protein localized in the nucleus of both myocytes and non-myocytes. Nuclear extracts from stretched myocytes contained DNA binding activity to the AP-1 and Egr-1 consensus sequences. In myocytes, the induction of immediate-early genes was followed by expression of "fetal" genes such as skeletal alpha-actin, atrial natriuretic factor, and beta-myosin heavy chain. DNA transfection experiments showed that the "stretch-response element" of the c-fos gene promoter is present within 356 base pairs of the 5'-flanking region, whereas that of the atrial natriuretic factor and the beta-myosin heavy chain genes is probably located outside of 3412 and 628 base pairs of the 5'-flanking region, respectively. These results demonstrate that the phenotype of stretched cardiocytes in this in vitro model closely mimics that of hemodynamic load-induced hypertrophy in vivo. This model seems to be a suitable system with which to dissect the molecular mechanisms of load-induced hypertrophy of cardiac muscle.

Adaptation, Physiological↗
PubMed1992

Stretching increases calcium influx and efflux in cultured pulmonary arterial smooth muscle cells.

To determine the effect of a single static stretch on calcium fluxes in cultured pulmonary arterial smooth muscle cells (PASMC), calcium influx and efflux were evaluated in PASMC on a collagen-coated silicone membrane using 45Ca2+ as a tracer. A single 20% linear stretch of the silicone membrane of 1 min in duration increased calcium uptake by 71%. This effect was partially inhibited by verapamil or gadolinium, but was not altered by staurosporine, pertussis toxin, or removal of extracellular sodium. Stretch-stimulated calcium uptake attenuated over time, such that uptake during the last minute of a 5-min sustained stretch was 46% of that during the first minute of stretch. A single 20% stretch sustained for 6 min caused a 47% increase in calcium efflux, the magnitude of which was linearly related to the degree of cell stretch. Gadolinium and removal of extracellular calcium each partially inhibited stretch-induced calcium efflux. We conclude that a single static stretch of PASMC causes increases in both calcium influx and efflux. Stretch-stimulated calcium influx does not require sodium influx and is mediated in part by a pathway sensitive to both gadolinium and verapamil. Stretch-stimulated calcium efflux is due to both calcium influx via a gadolinium-sensitive pathway and mobilization of intracellular stores. Because calcium is a key cellular second messenger, these effects of stretch on cellular calcium handling may play a role in the regulation of vascular smooth muscle cell phenotype and function.

Alkaloids↗
PubMed1992

Development and characterization of a cloned rat pulmonary arterial smooth muscle cell line that maintains differentiated properties through multiple subcultures.

BACKGROUND: Pulmonary hypertension is associated with abnormal pulmonary arterial contractility and growth. The mechanisms for these abnormalities are largely unknown. To study these processes, we sought to develop an in vitro system. Even though cultured aortic and pulmonary artery smooth muscle cells (SMCs) have been of considerable value in studying smooth muscle biology, one drawback of this system has been that these cells often lose differentiated properties in an unpredictable manner when they are passaged in culture. In addition, there appear to be significant differences in physiological and pathological responses between the systemic and pulmonary circulations, many of which could be directly related to the smooth muscle. We therefore established a cloned population of rat pulmonary arterial SMCs (PASMCs) that maintain differentiated properties through multiple subcultures. METHODS AND RESULTS: PASMCs were obtained initially by enzymatic dissociation from pulmonary arteries of adult Sprague-Dawley rats. From these cells, clones were isolated. The cloned cells retained expression of functional surface receptors for angiotensin II, norepinephrine, and alpha-thrombin and high levels of the smooth muscle isoforms of alpha-actin, myosin heavy chain, myosin regulatory light chain, and alpha-tropomyosin mRNAs even after multiple passages. The cells could also be transfected and processed exogenous transcripts in a smooth muscle-specific fashion. CONCLUSIONS: These cloned PASMCs retain many differentiated characteristics and should be valuable for future studies of pulmonary vascular smooth muscle cell biology.

Animals↗
PubMed1991

Stretch increases inositol trisphosphate and inositol tetrakisphosphate in cultured pulmonary vascular smooth muscle cells.

There are no reports of the effect of stretch on inositol phosphates in smooth muscle. Phosphoinositide and inositol phosphate metabolism was studied in cultured rat vascular smooth muscle cells subjected to stretching. The masses of inositol trisphosphate and tetrakisphosphate increased (+34 +/- 7% and +58 +/- 12%, respectively; p less than 0.001) after 25 s of a single 20% stretch and had returned to control levels by 45 s; phosphatidylinositol, phosphatidylinositol phosphate and bisphosphate did not change. Repetitive stretch did not alter the masses of any of the compounds. A single stretch also increased 45Ca2+ efflux (+52 +/- 5%, p less than 0.01). These data suggest that stretch of cultured vascular smooth muscle can elicit a rapid, short-lived increase in inositol phosphates, which may subsequently affect Ca2+.

Animals↗
PubMed1991

Inhibition of contraction of isolated lymphatic ducts by atrial natriuretic peptide.

Atrial natriuretic peptide (ANP) potently relaxes blood vessels but its effect on lymphatic motility is unreported. We studied the effect of ANP, and the smooth muscle relaxing agent nitroprusside (NP), on isolated ovine mesenteric lymphatic ducts. Duct segments were mounted on a myograph, and noncumulative dose-response curves were obtained for the effect of ANP and NP on the rate and force of spontaneous (and norepinephrine-induced) duct contraction. Both ANP (threshold approximately 1 nM) and NP (threshold approximately 10 nM) in a dose-related fashion reduced the frequency and force of contraction of both spontaneously contracting and norepinephrine-stimulated duct segments. ANP may therefore affect interstitial fluid balance through its effect on lymphatic motility.

Animals↗
PubMed1990

The "laid-back" aortogram: an improved angiographic view for demonstration of coronary arteries in transposition of the great arteries.

Preoperative demonstration of coronary arterial anatomy may be important for babies undergoing the arterial switch operation. Echocardiography is clearly useful, but may not unequivocally show all coronary branches. Standard angiographic views can be confusing. An improved angiographic projection in which the frontal x-ray tube is caudally angled, resulting in a "laid-back" position of the image intensifier and cine camera, provides superior visualization of the coronary arteries and their relation to the aorta and the pulmonary artery. The balloon occlusion technique is used for opacification of the aortic root from the transvenous approach. Injection of 1 ml/kg of contrast delivered in 1/2 to 1 second provides the best images. The caudal aortogram is easier to interpret than standard views and facilitates description and recognition of various coronary patterns. The relation between the pulmonary artery and the aorta, the origins of the coronary arteries from the facing sinuses and their proximity to the intercoronary commissures, and the myocardial distribution of each coronary vessel are shown clearly. The caudal view therefore offers significant advantages over conventional projections for demonstration of coronary arterial anatomy in infants with transposition of the great arteries or double-outlet right ventricle.

Aortography↗
PubMed1989

Pulmonary hypertension and asthma in two patients with congenital heart disease.

Reactive airway disease has only rarely been associated with pulmonary hypertension. We treated two patients with congenital heart disease and asthma who had increased pulmonary arterial pressure at cardiac catheterization. Pulmonary hypertension could not be explained solely by the cardiac lesion, nor by respiratory mechanical factors, as the patients did not have wheezing during the catheterization study. After long-term treatment with bronchodilators, corticosteroids, and oxygen, and coincident with improvement in the airway disease, there was catheterization-proved diminution of pulmonary hypertension. Whether asthma and pulmonary hypertension were causally linked is unknown, but further work seems indicated to elucidate the relationship between bronchoconstriction and pulmonary vasoconstriction. Furthermore, aggressive management of even mild reactive airway disease may be warranted in patients with pulmonary hypertension, regardless of apparent cause.

Asthma↗
PubMed1988

Stretch-induced contraction in pulmonary arteries.

Stretch stimulates contraction of systemic blood vessels, but the response has not been described in pulmonary vessels. To determine whether pulmonary arteries contract when stretched, isolated cylindrical segments of pulmonary arteries were suspended between two parallel wires, stretched, and the active force was generated in response to stretch measured. Eighty-nine percent of segments from small (in situ diameter less than 1,000 microns) feline pulmonary arteries contracted when stretched, and in 65% of these the magnitude of stretch was related to the magnitude of contraction. Large (in situ diameter greater than or equal to 1,000 microns) feline pulmonary arteries did not contract with stretch. Multiple, rapidly repeated stretches resulted in a diminution of active force development. Stretch-induced contraction required external Ca2+ and was abolished by diltiazem (10 microns), but it was not affected by phenoxybenzamine, phentolamine, diethylcarbamazine, or mechanical removal of endothelium. Indomethacin blunted but did not abolish stretch-induced contraction, an effect that may have been nonspecific. This study suggests that stretch can act, probably directly, on smooth muscle in small feline pulmonary arteries to elicit contraction and that it may be a determinant of pulmonary vascular tone. In addition, feline pulmonary arteries are suitable for the in vitro study of stretch-induced contraction.

Animals↗
PubMed1988

Pulmonary and systemic vascular effects of serotonin in conscious newborn lambs.

There is evidence that serotonin (5-hydroxytryptamine) may be released from pulmonary neuroendocrine cells during hypoxia in animals. Because there are few data regarding serotonin's effect on the immature pulmonary circulation, we studied the direct pulmonary (and systemic) vascular effects of this amine in awake lambs. As has been observed in mature animals, we found that serotonin is a powerful pulmonary and systemic vasoconstrictor, with a threshold of 3 micrograms/kg in immature lambs. However, unlike in mature animals, phenoxybenzamine, 2 mg/kg, prevented both the pulmonary (and systemic) vasoconstriction seen with serotonin. Serotonin is a powerful pulmonary vasoconstrictor in immature lambs, which is consistent with the idea that release of serotonin from pulmonary neuroendocrine cells may play a role in the hypoxic pulmonary vasoconstrictor response.

Animals↗
PubMed1987

Balloon dilation of the aortic valve: studies in normal lambs and in children with aortic stenosis.

To evaluate the risks of and optimal method for valve dilation in aortic stenosis, balloons of different sizes were used to dilate the normal aortic root in 16 lambs and then stenotic valves in 15 children. In the lambs, inflated balloon to aortic anulus diameter ratios ranged from 0.9 to 1.5. These hearts were examined immediately after the procedure. Ratios of 0.9 to 1.1 did not produce significant damage to the left ventricular outflow tract, whereas those of 1.2 to 1.5 produced tears or hematomas, or both, of the aortic valve leaflets (n = 3), mitral valve leaflets (n = 4) and interventricular septum (n = 4). The 15 patients, aged 10 days to 15 years, underwent 16 balloon aortic valvotomy procedures. The balloon-aortic anulus ratio ranged from 0.67 to 1.1 (mean 0.90). The average pressure gradient decreased 69% and, overall, the peak systolic gradient decreased from 86 +/- 21 to 28 +/- 14 mm Hg (p less than 0.01) and the aortic valve area increased from 0.44 +/- 0.11 to 0.73 +/- 0.22 cm2/m2 (p less than 0.01). Immediately after the procedure an increase in aortic regurgitation was noted in 8 (57%) of 14 patients, but was never greater than 3+ and has been well tolerated. Other early complications encountered consisted of transient left bundle branch block in two patients, temporary femoral artery occlusion in three and femoral artery rupture requiring operative management in one infant. Balloon valvotomy can reduce the transvalvular gradient in most patients with valvular aortic stenosis when a balloon less than 1.1 times the aortic root diameter is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Effects of static and fluctuating airway pressure on intact pulmonary circulation.

The direct effects on the pulmonary circulation of static and fluctuation airway pressure were compared in intact close-chest infant lambs with reactive pulmonary vasculature under alpha-chloralose anesthesia. A preparation developed to permit independent ventilation of right and left lungs and independent measurement of right and left lung blood flow was employed to separate direct from indirect effects of unilateral airway pressure changes on pulmonary vascular resistance (PVR). Both static and fluctuating unilateral airway pressure interventions directly elevated ipsilateral PVR. For purposes of comparison mean alveolar pressure (PA) was estimated for both static and fluctuating trials. Fluctuating interventions increased PVR more than did static trials at comparable levels of PA. Substantially less PA was needed to double ipsilateral PVR by fluctuating than by static interventions (16 vs. 26 mmHg, respectively). These data indicate that, in the intact animal with reactive pulmonary vasculature, both PA and the waveform of airway pressure applied can influence PVR.

Animals↗
PubMed1986

The effects of substance P on the preconstricted pulmonary vasculature of the anesthetized dog.

Substance P is a vasoactive peptide. Nerve fibers containing substance P are present in the media of pulmonary arteries but the physiologic function of substance P in the pulmonary vasculature is unknown. Several doses of substance P were infused intravenously in the anesthetized dog to ascertain its effects on the pulmonary vasculature, both during normoxia and following preconstriction with hypoxia (F1O2 0.1) or prostaglandin F2 alpha (PGF2 alpha 5 mug/kg/min). Substance P resulted in systemic vasodilation during normoxia but had minimal effect on the pulmonary vasculature. During hypoxia and PGF2 alpha-induced pulmonary vasoconstriction, substance P significantly lowered pulmonary artery pressure, pulmonary vascular resistance, mean aortic pressure, and total systemic resistance. It had no effect on cardiac output, wedge pressure, and arterial blood gases. To investigate possible mechanisms for substance P-induced vasodilation, substance P was studied following pretreatment with N-acetylcysteine (a radical scavenging agent), methylene blue (an inhibitor of guanylate cyclase), meclofenamate (a cyclooxygenase inhibitor), and atropine (a muscarinic receptor antagonist). None of these agents impaired substance P-induced vasodilation. Substance P given intravenously is a nonselective vasodilator in the dog but the mechanism of its action remains uncertain.

Acetylcysteine↗