A randomized controlled trial investigating the value of patient-specific instrumentation for total knee arthroplasty in the Canadian healthcare system.

AIMS: The purpose of the present study was to compare patient-specific instrumentation (PSI) and conventional surgical instrumentation (CSI) for total knee arthroplasty (TKA) in terms of early implant migration, alignment, surgical resources, patient outcomes, and costs. PATIENTS AND METHODS: The study was a prospective, randomized controlled trial of 50 patients undergoing TKA. There were 25 patients in each of the PSI and CSI groups. There were 12 male patients in the PSI group and seven male patients in the CSI group. The patients had a mean age of 69.0 years (sd 8.4) in the PSI group and 69.4 years (sd 8.4) in the CSI group. All patients received the same TKA implant. Intraoperative surgical resources and any surgical waste generated were recorded. Patients underwent radiostereometric analysis (RSA) studies to measure femoral and tibial component migration over two years. Outcome measures were recorded pre- and postoperatively. Overall costs were calculated for each group. RESULTS: There were no differences (p > 0.05) in any measurement of migration at two years for either the tibial or femoral components. Movement between one and two years was < 0.2 mm, indicating stable fixation. There were no differences in coronal or sagittal alignment between the two groups. The PSI group took a mean 6.1 minutes longer (p = 0.04) and used a mean 3.4 less trays (p < 0.0001). Total waste generated was similar (10 kg) between the two groups. The PSI group cost a mean CAD$1787 more per case (p < 0.01). CONCLUSION: RSA criteria suggest that both groups will have revision rates of approximately 3% at five years. The advantages of PSI were minimal or absent for surgical resources used and waste eliminated, and for meeting target alignment, yet had significantly greater costs. Therefore, we conclude that PSI may not offer any advantage over CSI for routine primary TKA cases. Cite this article: Bone Joint J 2019;101-B:565-572.

Coregulation of calcium channels and beta-adrenergic receptors in cultured chick embryo ventricular cells.

To examine mechanisms whereby the abundance of functional Ca channels may be regulated in excitable tissue, Ca channel number was estimated by binding of the dihydropyridine (DHP) antagonist 3H (+)PN200-110 to monolayers of intact myocytes from chick embryo ventricle. Beta adrenergic receptor properties were studied in cultured myocytes using [3H]CGP12177, an antagonist ligand. Physiological correlates for alterations in DHP binding site number included 45Ca uptake and contractile response to (+)BAYk 8644, a specific L-type Ca channel activator. All binding and physiological determinations were performed in similar intact cell preparations under identical conditions. 4-h exposure to 1 microM isoproterenol reduced cell surface beta-adrenergic receptor number from 44 +/- 3 to 17 +/- 2 fmol/mg (P less than 0.05); DHP binding sites declined in number from 113 +/- 25 to 73 +/- 30 fmol/mg (P less than 0.03). When protein kinase A was activated by a non-receptor-dependent mechanism, DHP binding declined similarly to 68% of control. Exposure to diltiazem, a Ca channel antagonist, for 18-24 h had no effect on number of DHP binding sites. After 4-h isoproterenol exposure, 45Ca uptake stimulated by BAYk 8644 declined from 3.3 +/- 0.2 nmol/mg to 2.9 +/- 0.3 nmol/mg (P less than 0.01) and BAYk 8644-stimulated increase in amplitude of contraction declined from 168 +/- 7 to 134 +/- 11% (P = 0.02). Thus, elevation of [cAMP] in myocytes is associated with a time-dependent decline in Ca channel abundance as estimated by DHP binding and a decline in physiological responses that are in part dependent on abundance of Ca channels. Binding of a directly acting Ca channel antagonist for 18-24 h does not modulate the number of DHP binding sites.

Enkephalins increase cyclic adenosine monophosphate content, calcium uptake, and contractile state in cultured chick embryo heart cells.

Peripheral vascular effects of opioid peptides are well known, but direct myocardial effects have not been established. We studied the inotropic response of spontaneously beating cultured chick embryo ventricular cells to the enkephalin analogue [D-Ala2]-enkephalin. Amplitude of cell motion increased in a concentration-dependent manner with 0.53 microM [D-Ala2]-enkephalin producing half-maximal response. The mechanism of this positive inotropic effect was investigated by examining alterations in 45Ca influx, cyclic AMP accumulation and adenylate cyclase activity in response to [D-Ala2]-enkephalin. At maximally inotropic concentrations, the 45Ca influx rate increased 39%, adenylate cyclase was stimulated by 30%, and cyclic AMP content rose more than twofold. Thus, in contrast to neural tissue, receptors for enkephalin in cultured heart cells are coupled to adenylate cyclase in a stimulatory manner. Occupancy of these receptors produces an increase in cyclic AMP levels and exerts a positive inotropic effect via a verapamil-sensitive enhancement of Ca influx.

Effects of morphine on coronary and left ventricular dynamics in conscious dogs.

We studied the effects of i.v. 2 mg/kg morphine sulfate (MS) on coronary blood flow and resistance, left ventricular (LV) diameter and pressure (P), rate of change of pressure (dP/dt), and dP/dt/P in conscious dogs. An initial transient reduction in coronary vascular resistance, associated with increases in heart rate, dP/dt, dP/dt/P, and reductions in LV end-diastolic and end-systolic size were observed. This was followed by a prolonged increase in mean coronary vascular resistance, lasting from 5 to 30 min, while heart rate, arterial pressure, and LV end-diastolic diameter returned to control levels and dP/dt/P remained slightly but significantly above control. At 10 min, late diastolic coronary flow had fallen from 44 plus or minus 3 ml/min to a minimum level of 25 plus or minus 3 ml/min, while late diastolic coronary resistance had risen from 1.68 plus or minus 0.10 to 3.04 plus or minus 0.28 mm Hg/ml/min. Morphine also induced substantial coronary vasoconstriction when heart rate was held constant. Neither the MS-induced coronary vasoconstriction nor the positive inotropic response was abolished by bilateral adrenalectomy. The positive inotropic response of MS was reversed after beta blockade, but not the coronary vasoconstriction. Alpha receptor blockade abolished the late coronary vasoconstriction effects of morphine, and only dilatation occurred. In anesthetized dogs MS failed to produce late coronary vasoconstriction. Coronary after a respiratory-depressant dose of morphine, 10 mg/kg i.v. Smaller doses of MS, 0.25 mg/kg every 15 min, produced significant coronary vasoconstriction after a total dose of 0.75 mg/kg in the conscious dogs. The effects of morphine may differ in the normal dog and man and may vary depending upon the presence or absence of coronary artery disease. However, in the normal conscious dog, MS elicits a mild beta adrenergic increase in contractility and an important coronary vasoconstrictor effect, which is mediated through alpha adrenergic receptors.

Effect of thyroid hormone on slow calcium channel function in cultured chick ventricular cells.

The hyperthyroid state is associated with increased myocardial contractility. To clarify responsible mechanisms, we examined the effects of thyroid hormone on slow Ca channels, beta-adrenergic receptors, transsarcolemmal 45Ca flux and cytosolic free calcium in cultured chick ventricular cells. Compared with cells grown without triiodothyronine (T3), cells grown in 10 nM T3 possessed 67% (P less than 0.05) more dihydropyridine 3H-PN200-110 binding sites, 24% (P less than 0.05) more beta-adrenergic antagonist 3H-CGP12177 binding sites, a 57% (P less than 0.05) greater nifedipine-sensitive initial 45Ca uptake rate, and a 31% (P less than 0.05) greater nifedipine-sensitive 45Ca uptake rate in response to BAY k 8644. Time-averaged mean intracellular free Ca concentration ([Ca]i) measured with fura-2, total protein content, and dissociation constant values for 3H-PN200-110 or 3H-CGP12177 binding was not significantly different in the two groups of cells. BAY k 8644 (1 microM) increased mean [Ca]i 2.85- or 2.16-fold in cells grown with or without 10 nM T3, respectively. l-Isoproterenol (1 microM) increased [Ca]i 1.53- or 1.28-fold in cells grown with or without 10 nM T3, respectively. We conclude that thyroid hormone augments transsarcolemmal Ca influx, at least in part via slow Ca channels associated with increased numbers of these channels. T3-treated cells appear to be more responsive to the effects of BAY k 8644 or isoproterenol on [Ca]i.

Direct contact between sympathetic neurons and rat cardiac myocytes in vitro increases expression of functional calcium channels.

To test the hypothesis that direct contact between sympathetic neurons and myocytes regulates expression and function of cardiac Ca channels, we prepared cultures of neonatal rat ventricular myocytes with and without sympathetic ganglia. Contractile properties of myocytes were assessed by an optical-video system. Contractility-pCa curves showed a 60% greater increase in contractility for innervated myocytes compared with control cells at 6.3 mM [Ca]0 (n = 8, P less than 0.05). Cells grown in medium conditioned by growth of ganglia and myocytes were indistinguishable physiologically from control cells. [Bay K 8644]-contractility curves revealed a 60 +/- 10% enhancement of the contractility response at 10(-6) M for innervated cells compared with control cells. The increased response to Bay K 8644 was not blocked by alpha- or beta-adrenergic antagonists. Moreover, increased efficacy of Bay K 8644 was maintained for at least 24 h after denervation produced by removal of ganglia from the culture. Dihydropyridine binding sites were assessed with the L channel-specific radioligand 3[H]PN200-110. PN200-110 binding sites were increased by innervation (51 +/- 5 to 108 +/- 20 fmol/mg protein, P less than 0.01), with no change in KD. Peak current-voltage curves were determined by whole-cell voltage clamp techniques for myocytes contacted by a neuron, control myocytes, and myocytes grown in conditioned medium. Current density of L-type Ca channels was significantly higher in innervated myocytes (10.5 +/- 0.4 pA/pF, n = 5) than in control myocytes (5.9 +/- 0.3 pA/pF, n = 8, P less than 0.01) or myocytes grown in conditioned medium (6.2 +/- 0.2 pA/pF, n = 10, P less than 0.01). Thus, physical contact between a sympathetic neuron and previously uninnervated neonatal rat ventricular myocytes increases expression of functional L-type calcium channels as judged by contractile responses to Ca0 and Bay K 8644, as well as by electrophysiological and radioligand binding properties.

Hypertrophic stimuli induce transforming growth factor-beta 1 expression in rat ventricular myocytes.

Transforming growth factor-beta 1 (TGF-beta 1) is a peptide growth factor that may play a role in the myocardial response to hypertrophic stimuli. However, the cellular distribution, mechanism of induction, and source of increased TGF-beta 1 in response to hypertrophic stimuli are not known. We tested the hypothesis that the cardiac myocyte responds to hypertrophic stimuli with the increased expression of TGF-beta 1. In adult rat ventricular myocardium freshly dissociated into myocyte and nonmyocyte cellular fractions, the preponderance of TGF-beta 1 mRNA visualized by Northern hybridization was in the nonmyocyte fraction. Abdominal aortic constriction (7 d) and subcutaneous norepinephrine infusion (36 h) each caused ventricular hypertrophy associated with 3.1-fold and 3.8-fold increases, respectively, in TGF-beta 1 mRNA in the myocyte fraction, but had no effect on the level of TGF-beta 1 mRNA in the nonmyocyte fraction. In ventricular myocytes, norepinephrine likewise caused a 4.1-fold increase in TGF-beta 1 mRNA associated with an increase in TGF-beta bioactivity. This induction of TGF-beta 1 mRNA occurred at norepinephrine concentrations as low as 1 nM and was blocked by prazosin, but not propranolol. NE did not increase the TGF-beta 1 mRNA level in nonmyocytes, primarily fibroblasts, cultured from neonatal rat ventricle. Thus, the cardiac myocyte responds to two hypertrophic stimuli, pressure overload and norepinephrine, with the induction of TGF-beta 1. These data support the view that TGF-beta 1, released by myocytes and acting in an autocrine and/or paracrine manner, is involved in myocardial remodeling by hypertrophic stimuli.

Intracoronary infusion of dobutamine to patients with and without severe congestive heart failure. Dose-response relationships, correlation with circulating catecholamines, and effect of phosphodiesterase inhibition.

We infused dobutamine into the left main coronary artery of 24 patients with severe congestive heart failure (CHF) and 8 normal subjects without hemodynamic dysfunction. The maximal +dP/dt response to intracoronary (IC) dobutamine in CHF patients was only 37% of that in normals. This decrease in maximal response was not associated with a rightshift in the EC50 for dobutamine's effect on +dP/dt, or a decrease in the affinity of myocardial beta adrenergic receptors for dobutamine determined in vitro. In nine of the CHF patients, IC dobutamine infusion was followed by IC infusion of the phosphodiesterase inhibitor milrinone, and subsequently, by a second IC infusion of dobutamine. After IC milrinone, the increase in +dP/dt caused by IC dobutamine (74 +/- 10%) was significantly greater than that caused by the first infusion of dobutamine (52 +/- 11%; P less than 0.003) or milrinone (42 +/- 6%; P less than 0.001). Resting plasma norepinephrine was markedly elevated in CHF patients (837 +/- 208 ng/liter), but not in normal subjects (142 +/- 32 ng/liter); and the increase in +dP/dt caused by IC dobutamine was inversely related to resting plasma norepinephrine levels (r = -0.653; P less than 0.001). IC dobutamine caused a dose-related decrease in plasma norepinephrine (maximal effect, -160 +/- 31 ng/liter; P less than 0.001). Thus, (a) the maximal inotropic response to dobutamine is markedly depressed in patients with severe CHF, and is significantly greater after pretreatment with the phosphodiesterase inhibitor milrinone; (b) the impairment in inotropic response to dobutamine is inversely related to circulating norepinephrine levels; and (c) myocardial stimulation by dobutamine results in withdrawal of sympathetic tone.

Expression of dihydropyridine receptor (Ca2+ channel) and calsequestrin genes in the myocardium of patients with end-stage heart failure.

Cytoplasmic free calcium ions (Ca2+) play a central role in excitation-contraction coupling of cardiac muscle. Abnormal Ca2+ handling has been implicated in systolic and diastolic dysfunction in patients with end-stage heart failure. The current study tests the hypothesis that expression of genes encoding proteins regulating myocardial Ca2+ homeostasis is altered in human heart failure. We analyzed RNA isolated from the left ventricular (LV) myocardium of 30 cardiac transplant recipients with end-stage heart failure (HF) and five organ donors (normal control), using cDNA probes specific for the cardiac dihydropyridine (DHP) receptor (the alpha 1 subunit of the DHP-sensitive Ca2+ channel) and cardiac calsequestrin of sarcoplasmic reticulum (SR). In addition, abundance of DHP binding sites was assessed by ligand binding techniques (n = 6 each for the patients and normal controls). There was no difference in the level of cardiac calsequestrin mRNA between the HF patients and normal controls. In contrast, the level of mRNA encoding the DHP receptor was decreased by 47% (P less than 0.001) in the LV myocardium from the patients with HF compared to the normal controls. The number of DHP binding sites was decreased by 35-48%. As reported previously, expression of the SR Ca(2+)-ATPase mRNA was also diminished by 50% (P less than 0.001) in the HF group. These data suggest that expression of the genes encoding the cardiac DHP receptor and SR Ca(2+)-ATPase is reduced in the LV myocardium from patients with HF. Altered expression of these genes may be related to abnormal Ca2+ handling in the failing myocardium, contributing to LV systolic and diastolic dysfunction in patients with end-stage heart failure.

Regulation of calcium channel expression in neonatal myocytes by catecholamines.

Expression of the dihydropyridine (DHP) receptor (alpha 1 subunit of L-type calcium channel) in heart is regulated by differentiation and innervation and is altered in congestive heart failure. We examined the transmembrane signaling pathways by which norepinephrine regulates DHP receptor expression in cultured neonatal rat ventricular myocytes. Using a 1.3-kb rat cardiac DHP receptor probe, and Northern analysis quantified by laser densitometry, we found that norepinephrine exposure produced a 2.2-fold increase in DHP receptor mRNA levels at 2 h followed by a decline to 50% of control at 4-48 h (P < 0.02). The alpha-adrenergic agonist phenylephrine and a phorbol ester produced a decline in mRNA levels (8-48 h). The beta-adrenergic agonist isoproterenol and 8-bromo-cAMP produced a transient increase in mRNA levels. After 24 h of exposure to isoproterenol, 3H-(+)PN200-110 binding sites increased from 410 +/- 8 to 539 +/- 39 fmol/mg (P < 0.05). The number of functional calcium channels, estimated by whole-cell voltage clamp experiments, was also increased after 24 h of exposure to isoproterenol. Peak current density (recordings performed in absence of isoproterenol) increased from -10.8 +/- 0.8 (n = 23) to -13.9 +/- 1.0 pA/pF (n = 27) (P < 0.01). Other characteristics of the calcium current (voltage for peak current, activation, and inactivation) were unchanged. Exposure for 48 h to phenylephrine produced a significant decline in peak current density (P < 0.01). We conclude that beta -adrenergic transmembrane signaling increases DHP receptor mRNA and number of functional calcium channels and that alpha - adrenergic transmembrane signaling produces a reciprocal effect. Regulation of cardiac calcium channel expression by adrenergic pathways may have physiological and pathophysiological importance.

Bradykinin blocks angiotensin II-induced hypertrophy in the presence of endothelial cells.

Angiotensin-converting enzyme inhibitors block left ventricular hypertrophy in vivo. A component of this effect has been attributed to tissue accumulation of bradykinin. Little is known regarding the effect of bradykinin on cardiomyocytes. The objectives of the present study were to define the effects of bradykinin on isolated ventricular cardiomyocytes (from adult and neonatal rat hearts) and to determine the extent to which bradykinin blocks hypertrophy in vitro. Bradykinin was found to be a hypertrophic agonist, as defined by increased protein synthesis and atrial natriuretic peptide secretion and expression. Bradykinin (10 micromol/L) increased [3H]phenylalanine incorporation by 23+/-3% in adult and by 36+/-10% in neonatal cardiomyocytes. Constitutive atrial natriuretic peptide secretion by neonatal myocytes was increased 357+/-103%. All effects of bradykinin were abolished by the B2-kinin receptor antagonist Hoe 140. These increases were similar in magnitude to those observed with phenylephrine (20 micromol/L) and angiotensin II (1 micromol/L). However, in cardiomyocytes cocultured with endothelial cells, bradykinin did not increase protein synthesis. Angiotensin II increased [3H]phenylalanine incorporation by 24+/-3% in adult cardiomyocytes in monoculture and by 22+/-2% in adult rat cardiomyocytes cocultured with endothelial cells. Bradykinin abolished this angiotensin II-induced hypertrophy in myocytes cultured with endothelial cells but not in myocytes studied in the absence of endothelial cells. In conclusion, bradykinin has a direct hypertrophic effect on ventricular myocytes. The presence of endothelial cells is required for the antihypertrophic effects of bradykinin. The results suggest that the increase in local concentration of bradykinin associated with angiotensin-converting enzyme inhibition is an important mechanism by which hypertrophy can be blocked. Manifestation of this mechanism appears to require bradykinin-stimulated release of paracrine factor(s) from endothelial cells, which are also able to block the hypertrophic effects of Ang II.

Myocardial infarction in young patients.

Myocardial infarction in persons under the age of 45 years accounts for 6% to 10% of all myocardial infarctions in the United States. In this age group, it is predominantly a disease of men. Important risk factors include a family history of myocardial infarction before age 55 years, hyperlipidemia, smoking, and obesity. Unlike older patients, approximately half of young patients have single-vessel coronary disease, and in up to 20%, the cause is not related to atherosclerosis. Coronary angiography may be warranted in young patients with myocardial infarction to define the anatomy of the disease and to permit optimal management.

Pulmonary angiography. Application in a new spectrum of patients.

Guidelines that are frequently used to select patients with suspected pulmonary embolus for pulmonary angiography evolved from studies conducted 10 to 15 years ago. To determine if clinical practice in a referral medical center should continue to be based on these guidelines, clinical and angiographic data on 106 patients recently studied were compared with similar data obtained from the same institution in the previous era. The need to perform angiography if a lung scan demonstrated low or high probability for embolus was also examined, along with clinical, laboratory, and hemodynamic findings previously reported to be of diagnostic utility. There has been a marked change in the spectrum of patients studied. Cancer patients and patients who have undergone abdominal and pelvic surgery comprise the preponderance of patients undergoing angiography. Lung scans had a clinically important error rate in that more than one third of these selected patients with either a high- or low-probability scan had discordant results on angiography. Clinical criteria for selecting patients for pulmonary angiography should reflect the contemporary spectrum of patients with pulmonary embolus, as well as the limitations of clinical judgment and of the lung scan.

Angina pectoris as the initial manifestation of an aortocaval fistula.

Spontaneous aortocaval fistula is an unusual disorder associated with abdominal aortic aneurysms and with the onset of high-output heart failure. A novel case of spontaneous aortocaval fistula formation that presented with angina is described. Increased myocardial oxygen demand due to elevated myocardial wall tension, inotropic state, and heart rate is the apparent contributing factor. Clinical evidence of ischemic heart disease and heart failure resolved with surgical correction of the shunt. Spontaneous aortocaval fistula formation can be a precipitating cause of new-onset angina.

Effect of metabolic inhibition on technetium-99m-MIBI kinetics in cultured chick myocardial cells.

Cellular uptake characteristics of hexakis(methoxyisobutylisonitrile)technetium(I) ([99mTc]MIBI), a myocardial perfusion imaging agent, were evaluated in cultured chick embryo heart cells. Myocyte net uptake of 99mTc-MIBI approached a plateau with a half-time of 9.3 +/- 1.5 min (mean +/- s.e.m.; n = 10). Tracer [99mTc]MIBI showed apparent competitive displacement by carrier [99Tc]MIBI at relatively high molar ratios ([99mTc]MIBI/[99Tc]MIBI) indicating a low affinity cellular retention process (apparent KD approximately 7 x 10(-5)). Metabolic inhibition induced by pre-incubation of cells for 2.5 hr in rotenone (10 microM), iodoacetate (1 mM), or both metabolic inhibitors together reduced 1-min [99mTc] MIBI uptake to 74.1% +/- 8.0% (p less than 0.05), 6.2% +/- 3.4% (p less than 0.01), and 10.1% +/- 3.6% of control (p less than 0.01), respectively (n = 11-12). Half-maximal inhibitory concentration of iodoacetate was approximately 5 microM. Iodoacetate inhibition of [99mTc]MIBI uptake kinetics was time-dependent; no significant effect on [99mTc]MIBI uptake was seen during the first 60 min of metabolic inhibition despite significant depletion of ATP content determined on the same preparations (control ATP: 40.2 nmoles/mg protein versus iodoacetate incubation: 2.8 nmoles/mg protein; p less than 0.01). However, prolonged metabolic blockade did eventually depress 1-min [99mTc]MIBI uptake. These data indicate that a late component of myocardial cell injury can depress [99mTc]MIBI cellular uptake.

No adaptation to digitalization as evaluated by digitalis receptor (Na,K-ATPase) quantification in explanted hearts from donors without heart disease and from digitalized recipients with end-stage heart failure.

Speculations about development of tolerance to the inotropic effect of digitalis have been engendered since studies in various in vitro systems and tissues not representative of the heart have shown up-regulation of sodium potassium adenosine triphosphatase (Na,K-ATPase) when exposed to digitalis. Moreover the digitalis receptor (i.e., Na,K-ATPase) concentration in the normal, vital human left ventricle has not been previously determined. On this basis, digitalis receptor concentration was quantified in the left ventricle of explanted hearts from subjects without heart disease and from patients with end-stage heart failure who had received digitalis therapy. This was performed using vanadate-facilitated 3H-ouabain binding to intact tissue samples giving values of 728 +/- 58 (n = 5) and 467 +/- 55 pmol/g wet weight (n = 6) (mean +/- SEM) (p < 0.005), respectively. However, some of the digitalis receptors may have retained digoxin before 3H-ouabain binding and thus may have escaped detection. To eliminate this effect of retained digoxin, samples were exposed to prolonged washing in buffer containing excess digoxin antibody, a method recently shown to clear digoxin from receptors and allow subsequent complete digitalis receptor quantification by 3H-ouabain binding. After washing in digoxin specific antibody, specific digitalis receptor concentration was 760 +/- 58 pmol/g (n = 5) and 614 +/- 47 pmol/g (n = 6) wet weight in samples of the normal and failing hearts, respectively (p < 0.08). Thus, digitalization was associated with occupancy of digitalis receptors in the failing human heart of 24% (p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism of heart failure caused by cardiac allograft rejection.

Rejection of the cardiac allograft is often associated with reversible myocardial failure, the mechanism of which is not understood. We have examined this phenomenon in a small animal model that provides the opportunity for multimodality study of the rejection process. Heterotopic cardiac transplantation was performed in the Lewis rat with Lewis X Brown-Norway (allografts) or Lewis (isografts) donors. Without immunosuppression, allografts are completely rejected in 6 to 8 days. At 3 days cardiac grafts were explanted and mounted on a modified Langendorff apparatus for functional measurements or submitted for pathologic examination and biochemical determination of high-energy phosphates. Three-day isografts (n = 9) had minimal histologic changes. Pathologic examination of 3-day allografts (n = 13) showed lymphocytic infiltrate and myocyte necrosis, histologic features for which antirejection treatment is usually given clinically. For grafts subjected to functional studies (n = 11), heart rate, cardiac output, coronary flow, and stroke work were determined at baseline and in response to isoproterenol (3 x 10(-8) mol/ml). Three-day allografts (n = 6) and isografts (n = 5) had similar baseline function. The chronotropic response to isoproterenol was similar in allografts and isografts, but allografts had diminished cardiac output and stroke work after isoproterenol. Adenosine triphosphate levels were normal (41.9 nmol/mg) in 3-day allografts (n = 4). We have evaluated functional, biochemical, and pathologic changes associated with myocardial dysfunction during heterotopic cardiac transplant rejection in a small animal. This model reproducibly demonstrates diminished contractile reserve in 3-day allografts with normal baseline function and high-energy stores but histologically significant rejection.

Improved recovery of heart transplants by combined use of oxygen-derived free radical scavengers and energy enhancement.

Oxygen free radical injury during reperfusion of ischemically stored heart transplants may further impair the ability of the transplanted heart to reuse substrate for recovery. We compared the effects of oxygen free radical scavengers, superoxide dismutase and catalase, either alone or combined with glucose-insulin-potassium, in an improved model of the heterotopically transplanted rat heart. Group 1 hearts (n = 8) received no preservation before transplantation and were transplanted immediately. Hearts in four other groups (n = 8 for each group) underwent cold storage (4 degrees to 6 degrees C) for 3 1/2 hours before transplantation. Five minutes before reperfusion of the transplanted hearts, recipient rats received one of the following intravenous treatments: saline (group 2), glucose-insulin-potassium (group 3), superoxide dismutase/catalase (group 4), and superoxide dismutase/catalase plus glucose-insulin-potassium (group 5). Left ventricular end-diastolic pressure, rate of rise of left ventricular pressure, myocardial blood flow, coronary resistance, and tissue adenosine triphosphate content of the heart transplants were assessed during or at the end of 2 hours of reperfusion. Hearts treated with superoxide dismutase/catalase alone showed improvement of end-diastolic pressure and myocardial blood flow. The use of glucose-insulin-potassium alone did not facilitate the recovery of transplanted hearts. In contrast, the combined use of superoxide dismutase/catalase plus glucose-insulin-potassium resulted in a superior recovery of all functional and hemodynamic parameters. These results indicate that free radical scavengers in the presence of glucose-insulin-potassium significantly improve functional recovery in the setting of heart transplantation.

Piretanide: a loop-active diuretic. Pharmacology, therapeutic efficacy and adverse effects.

Piretanide is a high-ceiling, loop-active diuretic that has been developed for treatment of congestive heart failure, hypertension and edematous states caused by renal and hepatic diseases. Piretanide is structurally related to furosemide and bumetanide; when administered orally, 6 mg of piretanide is as effective as 40 mg of furosemide, and when administered intravenously, 12 mg of piretanide is as effective as 40 mg of furosemide. Piretanide enhances water and sodium excretion in patients with congestive heart failure, with nephrotic syndrome and with cirrhosis and ascites. Adverse effects reported to date are limited to those attributable to excess loss of fluid and electrolytes. Under some conditions, piretanide appears to be less potassium wasting than thiazide diuretics or other loop-active diuretics.

Effect of serotype 2 and 3 Marek's disease vaccines on the development of avian leukosis virus-induced pre-neoplastic bursal follicles.

The effect of serotype 2 and 3 Marek's disease virus (MDV) vaccines on the development of pre-neoplastic bursal lesions induced by two strains of subgroup A avian leukosis virus (ALV) was studied. Chickens of line 15I5 x 7(1) susceptible to ALV-induced lymphoma were inoculated at hatch with Rous-associated virus-1 (RAV-1) or strain RPL-40 of subgroup A ALV. All chickens, except for negative controls, were also inoculated at hatch with strain 301B/1 of serotype 2 MDV or strain FC126 of turkey herpesvirus (HVT), a serotype 3 MDV. At 11 and 14 weeks of age, serial sections of bursal tissues from chickens in various treatment groups were stained with methyl green pyronin and examined for ALV-induced pre-neoplastic bursal lesions, also known as hyperplastic follicles. At 6 days and at 11 and 14 weeks of age, bursal tissues from groups of chickens inoculated with serotype 2 MDV and ALV at hatch were also examined for the presence of MDV genome by in situ hybridization. The number of ALV-induced hyperplastic follicles was significantly higher in chickens inoculated with serotype 2 MDV than in unvaccinated chickens or in chickens vaccinated with HVT. In contrast, the lowest number of hyperplastic follicles was noted in chickens vaccinated with HVT, regardless of strain of ALV used. These results suggest that enhancement of lymphoid leukosis may result from an increase in the number of ALV-induced hyperplastic follicles caused by the MDV and also that the enhancing effect of MDV on ALV-induced lymphomagenesis may occur at the stage of formation of hyperplastic follicles in the bursa.