Hypoxanthine uptake by skeletal muscle microvascular endothelial cells from equilibrative nucleoside transporter 1 (ENT1)-null mice: effect of oxidative stress.

Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase transporter (ENBT1) which is involved in the cellular flux of adenosine metabolites such as hypoxanthine. Changes in either of these transport systems would impact the bioactivity of adenosine and its metabolism, including the formation of oxygen free radicals. MVEC isolated from skeletal muscle of ENT1(+/+) and ENT1(-/-) mice were subjected to oxidative stress induced by simulated ischemia/reperfusion or menadione. The functional activities of ENT1 and ENBT1 were assessed based on zero-trans influx kinetics of radiolabeled substrates. There was a reduction in the rate of ENBT1-mediated hypoxanthine uptake by ENT1(+/+) MVEC treated with menadione or after exposure to conditions that simulate ischemia/reperfusion. In both cases, the superoxide dismutase mimetic MnTMPyP attenuated the loss of ENBT1 activity, implicating superoxide radicals in the response. In contrast, MVEC isolated from ENT1(-/-) mice showed no reduction in ENBT1 activity upon treatment with menadione or simulated ischemia/reperfusion, but they did have a significantly higher level of catalase activity relative to ENT1(+/+) MVEC. These data suggest that ENBT1 activity is decreased in MVEC in response to the increased superoxide radical that is associated with ischemia/reperfusion injury. MVEC isolated from ENT1(-/-) mice do not show this reduction in ENBT1, possibly due to increased catalase activity.

Werdnig-Hoffmann disease: report of the first case clinically identified and genetically confirmed in central Africa (Kinshasa-Congo).

Werdnig-Hoffmann Disease: Report of the first case clinically identified and genetically confirmed in Central Africa (Kinshasa-Congo): Type 1 spinal muscular atrophy (SMA1) or Werdnig-Hoffman disease is rarely described in black populations. We report on one black patient diagnosed in Kinshasa. This patient was referred to Paediatric consultation at the age of 5 months 1/2 with extreme hypotonia progressing since birth, severe muscular weakness in his trunk and proximal parts of the extremities, ASD type II, and repeated episodes of pulmonary infections. He died of severe respiratory failure at the age of 10 months. EMG analysis revealed motor neuron a defect without nerve conduction anomaly, suggesting the diagnosis of spinal muscular atrophy disease. The diagnosis of SMA1 was definitely confirmed by a quantitative PCR-based testing that demonstrated homozygous deletion of SMN1, the primary disease-causing gene for spinal muscular atrophy, while two normal SMN2 alleles were present. There was a history of similar clinical symptomatology in a patient's older brother, suggesting a familial involvement. To the best of our knowledge, this is the first documented Werdnig-Hoffman case ever reported from Central Africa people.

Percutaneous transluminal coronary angioplasty in patients with prior coronary bypass surgery.

To improve symptomatic status and avoid reoperation, 122 initial and 7 repeat percutaneous transluminal coronary angioplasty procedures were performed in 116 patients with disabling angina pectoris at a mean of 26.8 months (range 2 to 132) after coronary bypass surgery. Marked angiographic improvement (greater than 30% reduction in diameter stenosis) was obtained in 107 (88%) of the 122 initial procedures and in all 7 repetitions. Mean stenosis was reduced from 78 +/- 13% (mean +/- standard deviation) to 25 +/- 13% (p less than 0.0001) and mean pressure gradient from 49 +/- 15 to 11 +/- 8 mm Hg (p less than 0.0001). Complications were: emergency surgery (three patients), Q wave infarction (one patient), myocardial infarction by enzyme criteria only (four patients) and non-occluding coronary dissection (one patient). There were no neurologic or peripheral vascular complications and no early deaths. One late death occurred 14 months after an unsuccessful but uncomplicated angioplasty procedure. At a mean follow-up of 8.3 months, 88 patients (76%) were free of angina or in improved condition. In patients followed up for at least 6 months, evidence of restenosis occurred in 9 (53%) of 17 saphenous veins, 1 (50%) of 2 proximal graft anastomoses, 4 (18%) of 22 distal graft anastomoses and 5 (14%) of 37 native coronary arteries. When coronary anatomy is suitable, percutaneous transluminal angioplasty is an attractive alternative to reoperation in symptomatic patients with prior coronary bypass surgery.

Thallium-201 myocardial tomography with a rotating slant-hole collimator and a large number of projections.

Tomographic imaging of the myocardium was performed using a gamma camera and a 30-degree rotating slant-hole collimator to register 64 projections from a restricted-view angle. Section images were reconstructed with a two-dimensional filtered backprojection technique. Performance in terms of resolution, effects of misalignment, and three-dimensional activity distribution was evaluated in phantom studies. In a limited clinical study, ten consecutive patients were imaged both with single-photon emission computed tomography (SPECT) and the method described. In the new method, the camera was orientated in the 30 degrees left anterior oblique position with 15 degrees cranial tilt. Due to the short distance from the myocardium to the camera, resolution within reconstructed section images was high, the noise level was comparatively low, and the mean activity level in the posterior wall was significantly higher (p less than 0.005) than in SPECT.

Tomography using a rotating slant-hole collimator and a large number of projections.

A tomographic method using a limited-view angle has been evaluated. In studies using a gamma camera and a rotating 30-degree slant-hole (RSH) collimator, 64 projection images were registered. A special filtered backprojection technique was used for reconstruction of section images parallel to the collimator face. Resolution within such sections was 0.6 cm, 3 cm from the collimator face and 1.3 cm at 18 cm. Depth resolution was 2.2 cm at 3 cm and 5.1 cm at 18 cm. Spacing between section images was regular and geometric distortion negligible. Short-axis section images of a myocardium in vivo were qualitatively comparable or better than those obtained with single-photon emission computed tomography. Degradation in the posterior wall due to attenuation and scatter was less. Section images of the facial bones and a hip joint further demonstrated the tomographic capability of the method.

Comparison of SPECT and ectomography for evaluating myocardial perfusion with technetium-99m-sestamibi.

UNLABELLED: This study compared myocardial perfusion scintigraphy performed with ectomography to corresponding SPECT studies. METHODS: In a comparative study between SPECT and ectomography, 19 patients with suspected coronary artery disease were imaged under similar conditions. A two-day protocol using 99mTc-sestamibi was followed. In SPECT, 32 projection images were acquired by rotating the gamma camera detector through 180 degrees, from 45 degrees left posterior oblique to 45 degrees right anterior oblique. Short-axis view sections and polar tomograms were reconstructed. In ectomography, a 30 degrees slant-hole collimator was rotated through 360 degrees in front of a stationary detector to obtain 64 projection images with different projection directions. The gamma camera was orientated perpendicular to the long axis of the left ventricle; the orientation was determined from the SPECT examination. Short-axis section images through the projected conical volume were reconstructed using a two-dimensional filtered back projection technique. In a blind test, the relative diagnostic value and image quality of the two methods were evaluated by three independent observers assessing short-axis view sections and polar tomograms. An objective evaluation based on relative values in the polar tomograms was also performed. The interpretations were evaluated with analysis of variance. RESULTS: After injection during exercise, there was no significant difference between SPECT and ectomography. After injection at rest, visualization of the left ventricle was superior (p < 0.05) and influence of external activity was less (p < 0.005) in ectomography. The activity level within a perfusion defect was significantly lower (p < 0.05) and its extension significantly larger (p < 0.05) in ectomography than in SPECT. There was no difference between the diagnosis based on SPECT or ectomography. CONCLUSION: In myocardial perfusion imaging with 99mTc-sestamibi, ectomography provides information similar to that obtained with SPECT and can, therefore, be used clinically for evaluation of myocardial perfusion when the gamma camera is postitioned perpendicular to the long axis of the left ventricle.

Importance of complete revascularization in performance of the coronary bypass operation.

Cardiac Data Bank records of 1,238 patients with triple-vessel disease (greater than or equal to 50% diameter reduction) who had undergone coronary bypass surgery were reviewed and divided into 2 groups depending on whether complete (n = 773) or incomplete (n = 465) revascularization had been accomplished. Patients with complete revascularization had a higher incidence of a normal preoperative electrocardiogram than did patients with incomplete revascularization (23 versus 14%, respectively, p less than 0.0001). The ejection fraction for both completely and incompletely revascularized patients was good (m = 0.60 and 0.57, respectively). The mean number of grafts per patient for the 2 groups was 3.8 and 2.6 (p less than 0.0001). There was no significant difference between the 2 groups with regard to postoperative inotropic requirements (8 and 7%), ventricular arrhythmias (1.8 and less than 1%), necessity for intraaortic balloon pumping (1.6 and 1.5%, hospital mortality (1.2 and 2.8%), or myocardial infarction (4.3 and 4.8%). Survival at 5 years was significantly greater (p less than 0.001) in patients with complete (88.5%) than in those with incomplete revascularization (83.5%). Reemployment occurred more often in patients with complete (52%) than in those with incomplete revascularization (40%) (p less than 0.001), and more patients were free of angina after complete (70%) than after incomplete revascularization (58%) (p less than 0.0005). Long-term survival appeared to be mediated primarily through improved revascularization rather than through differences in left ventricular function.

Complete atrioventricular canal associated with tetralogy of Fallot: clinical experience and operative methods.

Data on 8 children with the combined anomalies of complete atrioventricular canal and tetralogy of Fallot are presented. Six of the children had only a palliative procedure, and only 1 of these patients is doing relatively well at the present time from a clinical standpoint. Two of the remaining 5 children undergoing palliative procedures have not been helped significantly, and 3 of the children in this group subsequently died. Two children have had an attempted total correction of this complicated intracardiac problem. One of these children, in whom the diagnosis of atrioventricular canal was not made preoperatively, died in the early postoperative period. In the other child, the correct diagnosis was made preoperatively, and a satisfactory, totally corrective procedure was achieved. The patient is asymptomatic at this time.

Improved myocardial recovery after cardioplegic arrest with an oxygenated crystalloid solution.

Possible enhancement of myocardial protection by oxygenation of a crystalloid cardioplegic solution was evaluated in a three-part study. In Part I, canine hearts underwent ischemia followed by heterogeneous cardioplegic arrest for 45 to 60 minutes. Oxygenation led to improved recovery in the left anterior descending region (47% versus 86% recovery, p less than 0.05) (15 minutes of ischemia) and in the circumflex region (9.5% versus 52% recovery, p less than 0.05) (30 minutes of ischemia). Part II was a blind prospective randomized study in 12 patients. It examined creatine kinase, myoglobin, and lactate as well as coronary sinus flow, oxygen consumption, and cardiac work 1 hour after aortic cross-clamping during atrial and during ventricular pacing. No significant difference was demonstrable between control and oxygenated solutions. In Part III, 57 coronary bypass patients were protected with a nonoxygenated solution while 94 patients received an identical oxygenated solution. Twelve-hour creatine kinase levels were similar in the nonoxygenated (9.5 +/- 16 IU, +/- standard deviation) and oxygenated (11 +/- 22 IU) groups if the cross-clamp interval was 28 minutes or less. In patients subjected to longer than 28 minutes of arrest, the 12 hour creatine kinase MB levels were more than twice as high in the nonoxygenated group (26.5 +/- 26 IU) compared to the oxygenated group (9.9 +/- 14 IU, p less than 0.05). In this canine model of heterogeneous cardioplegia and in the routine conduct of coronary bypass operations, oxygenated crystalloid cardioplegia is superior to an identical nonoxygenated solution.

Recognition and management of ascending aortic dissection complicating cardiac surgical operations.

This study retrospectively reviews the hospital records of 24 patients who developed ascending aortic dissection during or following 6,943 cardiac surgical procedures performed from January, 1971, through December, 1981. Group I consists of 15 patients with ascending aortic dissection presenting intraoperatively during myocardial revascularization. Group II consists of nine patients, seven who underwent myocardial revascularization and two who underwent aortic valve replacement, who developed ascending aortic dissection 30 minutes to 21 days after cardiac operation. Four of these patients had poorly controlled hypertension postoperatively. Surgical repair was attempted in all patients in Group I, with an operative mortality of 33%. The major cause of death was myocardial dysfunction secondary to ischemia. There were no operative deaths among six patients managed with closed plication techniques alone. Four of nine patients in Group II underwent ascending aortic dissection repair with an operative mortality of 50%. The overall mortality in Group II was 78%. The major factor in this high mortality was a delay in diagnosis and surgical therapy. Early diagnosis of the intraoperative or postoperative ascending aortic dissection process is essential to minimize the extent of dissection and prevent delay of definitive surgical therapy. Closed aortic plication of the intimal injury rather than more extensive aortic repair may reduce morbidity and mortality in selected patients.

Combined carotid and coronary operations: when are they necessary?

Three groups of patients were analyzed to ascertain the risk of combined carotid/coronary operations and the risk factors for perioperative stroke following coronary artery bypass (CAB). Group 1 (N = 132) had simultaneous carotid endarterectomy and CAB, Group 2 (N = 51) were patients having perioperative stroke following elective CAB, and Group 3 (N = 169) had CAB alone but had prior history of either asymptomatic cervical bruit, stroke/transient cerebral ischemic attack (TIA), or carotid endarterectomy. Hospital mortality and perioperative stroke rate in the combined carotid/coronary group were 3.0% (4/132) and 1.6% (2/126), respectively. These rates were not significantly different from those of a control group having CAB alone. Overall incidence of postoperative stroke in 5,676 patients having CAB alone was 0.9% (51 patients). The incidence of perioperative stroke in patients with asymptomatic bruit or prior history of stroke or TIA undergoing CAB alone was 3.3% (2/60) and 8.6% (6/70), respectively. The majority of strokes following CAB appear to be embolic in origin. Indications for simultaneous carotid/coronary operations are bilateral carotid disease and symptomatic carotid vascular disease associated with unstable angina, left main obstruction, or diffuse multivessel disease. Staged procedures are recommended for patients with stable angina and symptomatic carotid lesions and for difficult carotid revascularization procedures. CAB alone may be performed for most patients with asymptomatic cervical bruit, moderate or mild carotid artery obstruction, and unstable angina associated with prior stroke, although in the third situation postoperative risk of neurological injury may be increased.

Porcine cardiac xenograft valves: analysis of survival, valve failure, and explantation.

Porcine cardiac xenografts were used for cardiac valve replacement in 1,093 patients. Hospital mortality for aortic valve replacement (AVR) was 3.7%; for mitral valve replacement (MVR), 7.8%; and for AVR + MVR, 4.7%. Total follow-up was 2,036 patient-years; maximum, 7.3 years; and mean, 1.89 years. Actuarial survival (+/- standard error of the mean) for AVR was 84% +/- 2% at 56 months; for MVR, 84% +/- 3% at 56 months; and for AVR + MVR, 86% +/- 4% at 30 months. Nonfatal thromboembolism occurred in 8 of 1,030 patients (0.78%). Anticoagulation was not routinely employed. Fifty hospital survivors (4.8%) experienced valve dysfunction; 18 of the survivors (1.7%) died; and 32 of the survivors (3.1%) underwent reoperation. The rate of dysfunction increased slowly until the sixth year when an increased rate was observed (p less than 0.0001). Patients less than 34 years old had a higher incidence of dysfunction (p less than 0.01). Thirty-two hospital survivors (3.1%) underwent explantation of the porcine valve for late dysfunction. Valve dysfunction secondary to endocarditis and paravalvular leak occurred early, while leaflet deterioration or thrombosis was more gradual in onset and was noted later. The porcine valve has functioned well for 1 to 7 years with a low incidence of valve related morbidity and mortality without routine anticoagulation in patients older than 34 years of age.

Unstable angina pectoris: comparison with the National Cooperative Study.

Seventy-eight patients having prolonged pain (greater than 20 minutes) with transient S-T segment and T-wave changes and coronary artery bypass were compared to 288 patients previously reported in the National Cooperative Study on the treatment of unstable angina pectoris. Clinical characteristics observed in the present study that differed from those of the National Cooperative Study included a more chronic anginal pattern, slightly older age, greater number of women, and higher incidence of prior myocardial infarction. The severity of vessel disease was the same for both groups. Left ventricular function was slightly better in the present series. The incidence of perioperative infarction in the present series (3.8%) was significantly less than that for surgical patients reported in the National Cooperative Study (17%). Hospital mortality was also less: 1.2% versus 2.0 and 3.0% for the medical and surgical patients, respectively, in the National Cooperative Study. Late myocardial infarction was 11% and 13% at 30 months for medical and surgical patients in the National Cooperative Study, and only 3% at 43 months in the present surgical series. Actuarial survival for the entire patient population was 95% at 42 months. The reduced hospital mortality and perioperative infarction rates were attributed to immediate operation once acute myocardial infarction has been ruled out, advances in surgical and anesthetic technique, selection of patients with preserved left ventricular function, and a trend toward complete revascularization.

Percutaneous transluminal coronary angioplasty: role of the surgeon.

Over a recent one-year period, 339 patients underwent percutaneous transluminal coronary angioplasty (PTCA) and were compared with 338 patients having isolated coronary artery bypass surgery. Patients undergoing PTCA had a shorter duration of angina, a lower number of prior myocardial infarctions, and better left ventricular function (p less than 0.01); PTCA was considered initially successful in 87% (295/339) of patients. Repeat angioplasty was performed in 18% of patients (34/339), with a successful outcome in all but 1. The most common finding at operation in those with failed angioplasty and urgent or emergency revascularization was dissection of an atheromatous plaque. There were 28 early failures (operation performed within 24 hours) and 24 late failures (operation at more than 24 hours), for early and late failure rates of 8.3% and 7.1%, respectively. Although the cumulative frequency of new Q-waves in the entire angioplasty series was low (2.7%), the incidence was high in those with angioplasty failure and subsequent operation (18%), and was significantly greater than in patients having elective coronary bypass (3.6%). Use of inotropic agents and lidocaine treatment for ventricular arrhythmias was also significantly higher in patients with unsuccessful PTCA who required operation than in those undergoing elective bypass (10% versus 3% and 10% versus 1.5%, respectively; p less than 0.01). Eleven of the 28 patients who were early failures were totally revascularized within 2 hours of angioplasty failure. Facilities and staff available for expedient revascularization accounted for the low morbidity and lack of mortality in PTCA failures.

Coronary bypass for relief of persistent pain following acute myocardial infarction.

Between January, 1976, and April, 1980, 116 patients had urgent myocardial revascularization for clinical instability within 30 days of acute myocardial infarction (MI). Group 1 (8 patients) had coronary bypass grafting within 24 hours of acute MI; Group 2 (20 patients) had coronary bypass grafting 2 to 7 days after acute MI; and Group 3 (88 patients) had coronary bypass grafting 8 to 30 days after infarction. Indications for operation were persistent or recurrent pain (81%), pain plus ventricular arrhythmias (12%), and pain plus compelling anatomy. The incidence of single-vessel, triple-vessel, and left main coronary artery disease was 28%, 31%, and 12%, respectively. There were no hospital deaths in the series. The incidence of inotropic requirements, postoperative intraaortic balloon pumping, ventricular arrhythmias, and perioperative infarction was higher in patients operated on within 7 days of acute MI than for patients having coronary bypass grafting after this time. There have been 5 late deaths during a mean follow-up of 14 months. Actuarial survival was 97% at 18 months. Seventy-one percent of patients are presently pain free. Graft patency was 84% in 17 patients recatheterized after coronary bypass grafting and in 14 patients, grafts placed into the area of infarction were patent. This study suggests that the frequency of perioperative complications will be increased in patients operated on within one week of MI, but after this period, coronary bypass grafting can be accomplished with the same morbidity as the of elective operation.

The impact of pleurodesis in malignant effusion on respiratory function.

Pleurodesis of malignant pleural effusion provides for a substantially better quality of life compared to onging exudation with the need for repeated evacuation of fluid. Successful pleurodesis leads to permanent cessation of fluid production as a result of the formation of fibrous adhesion between the lung and costal pleura which in theory, however, might restrict lung mobility. In patients with poor lung function, or with need for bilateral pleurodesis, the apprehension of further impairment of lung function often arises. The aim of this study was to evaluate the effects of pleurodesis on lung function. Therefore 10 patients with malignant pleurisy with very limited tumour were investigated. They were without radiological signs of tumour infiltration in the lung parenchyma, without visible tumour growth in the pleural space during thoracoscopy and had undergone a successful one-sided pleurodesis. Respiratory function tests were performed at different times, 1-102 months after pleurodesis. The assessment consisted of: static and dynamic spirometry, exercise testing with blood gas determination and radiospirometry. Spirometric values were slightly low, but in general within the reference limits. Blood gas determination showed no signs of alveolar hypoventilation. Radiospirometry showed a slight attenuation of activity in the treated lung but similar turnover of gas of the treated vs. the untreated side. The study showed that pleurodesis in malignant pleurisy has only minor impact on respiratory function.

Total variation norm for three-dimensional iterative reconstruction in limited view angle tomography.

An iterative Bayesian reconstruction algorithm for limited view angle tomography, or ectomography, based on the three-dimensional total variation (TV) norm has been developed. The TV norm has been described in the literature as a method for reducing noise in two-dimensional images while preserving edges, without introducing ringing or edge artefacts. It has also been proposed as a 2D regularization function in Bayesian reconstruction, implemented in an expectation maximization algorithm (TV-EM). The TV-EM was developed for 2D single photon emission computed tomography imaging, and the algorithm is capable of smoothing noise while maintaining edges without introducing artefacts. The TV norm was extended from 2D to 3D and incorporated into an ordered subsets expectation maximization algorithm for limited view angle geometry. The algorithm, called TV3D-EM, was evaluated using a modelled point spread function and digital phantoms. Reconstructed images were compared with those reconstructed with the 2D filtered backprojection algorithm currently used in ectomography. Results show a substantial reduction in artefacts related to the limited view angle geometry, and noise levels were also improved. Perhaps most important, depth resolution was improved by at least 45%. In conclusion, the proposed algorithm has been shown to improve the perceived image quality.

The porcine bioprosthesis. A review of 1,000 consecutive patients undergoing cardiac valve replacement.

Early and late experience with 1,000 patients undergoing porcine xenograft replacement of cardiac valves from 1974 through 1981 at Emory University Hospital is presented. Hemodynamic performance of the modified orifice Hancock and the Carpentier-Edwards valves has been quite satisfactory. There has been a low incidence of thromboembolism in the absence of routine anticoagulation. Less than 20 per cent of our patients are anticoagulated long-term, the primary indication being chronic artrial fibrillation. Endocarditis has developed in 0.7 per cent of patients, an incidence comparing most favorably with that of mechanical prostheses. Valve dysfunction secondary to primary tissue failure is a definite problem. The highest incidence of tissue failure occurred in young patients after six years of implantation. Detailed analysis of long-term patient survival showed a low incidence of valve related deaths. The porcine xenograft is a satisfactory prosthesis for cardiac valve replacement. Our data suggests its use should be limited to older patients or to patients in whom anticoagulation is contraindicated. It should be explained to all patients that long-term durability is unknown and that re-replacement of these bioprostheses within a decade is quite likely.

Effects of order of mixing and solute interactions on the "water activity" of concentrated solutions.

Experimental results indicate that order-of-mixing effects in concentrated sugar-salt solutions are functions of salt:sugar concentrations, types of sugars and salts, time after mixing of clear solutions, and solute interactions. Visual clarity of the solutions after preparation and at least 16 hours of storage may not be a sufficient indicator of complete solvation. The order of mixing solutes may cause differences in their rates of hydration, resulting in differences in "Aw" at non-equilibrium conditions, whereas Aw is only meaningful at thermodynamic equilibrium. Determining a thermodynamic equilibrium Aw in diffusion-resistant foods may take much more time and be more difficult to measure than in the solutions reported in this paper.

Evaluation of anastomoses of small intestine in dogs: crushing versus noncrushing suturing techniques.

Fifteen dogs were used to compare simple interrupted crushing and noncrushing single-layer small intestinal anastomoses. Groups of 5 dogs each were used to evaluate both techniques at 3 postsurgical times--days 4, 21, and 42. There were no significant differences between the 2 techniques at the evaluations. Grossly, there were marked adhesion formations at the 3 evaluation times. Luminal diameters at the anastomotic site indicated there may have been only slightly more stenosis with the noncrushing technique. Bursting pressure studies determined that the anastomotic strengths of the 2 techniques were not measurably different statistically. However, their bursting strengths had greatly increased from day 4 to day 21. There were also significant increases in bursting strengths of jejunal segments caudal to the anastomotic sites from day 4 to day 42. Subjective histopathologic evaluations of anastomotic sites revealed that the types and amounts of inflammation, collagen content, continuity of layers, and severity of peritonitis were not different within each time. It was concluded that both techniques for small intestinal anastomoses in the dog have equal value.