Reduced serum amino acid concentrations in infants with necrotizing enterocolitis

OBJECTIVE

To determine whether premature infants who have necrotizing enterocolitis (NEC) have deficiencies in glutamine (GLN) and arginine (ARG), which are essential to intestinal integrity.

STUDY DESIGN

A 4-month prospective cohort study of serum amino acid and urea levels in premature infants was done. Serum amino acid and urea levels were measured by high-pressure liquid chromatography and enzymatic methods, respectively, on samples obtained on days of life 3, 7, 14, and 21.

RESULTS

Infants in the control (n = 32) and NEC groups (n = 13) were comparable for birth weight, gestational age, and Apgar scores. NEC began on mean day of life 14.5 (95% CI, day of life 11 to 18). Median values of GLN were 37% to 57% lower in the NEC group on days 7, 14, and 21 compared with those in the control group (P <.05). On days 7 and 14, median values of ARG, GLN, alanine, lysine, ornithine, and threonine were decreased 36% to 67% (P <.05) in the NEC group. Total nonessential amino and total essential amino acids were 35% to 50% lower in the NEC group on days 7 and 14 (P <.05). Infants in the NEC group had significant reductions in GLN and ARG 7 days before the onset of NEC.

CONCLUSIONS

Infants who have NEC have selective amino acid deficiencies including reduced levels of GLN and ARG that may predispose to the illness.

Reduced ischemia-reperfusion injury with rolipram in rat cadaver lung donors: effect of cyclic adenosine monophosphate

BACKGROUND

The perfusion of rat lungs retrieved from cadavers with a solution containing isoproterenol has been shown to ameliorate the ischemia-reperfusion injury seen in lungs retrieved after death, and this protective effect parallels increases in tissue cyclic adenosine monophosphate levels. In this study, we investigated the effect of rolipram, a phosphodiesterase inhibitor, on capillary permeability and lung cyclic adenosine monophosphate levels in lungs retrieved from circulation-arrested rats.

METHODS

Using an isolated perfused lung circuit, we retrieved lungs from circulation-arrested donor rats either ventilated with 100% oxygen or not ventilated for varying postmortem times. The lungs were reperfused with or without rolipram (2 micromol/L). The capillary filtration coefficient and wet to dry weight ratio, indicators of pulmonary vascular integrity, were determined, and tissue levels of adenine nucleotides and cyclic adenosine monophosphate were measured by high-performance liquid chromatography.

RESULTS

The capillary filtration coefficient was significantly reduced in nonventilated cadaver lungs reperfused with rolipram 120 minutes after death (p<0.05). Oxygen ventilation or reperfusion with rolipram had a similar effect on the capillary filtration coefficient. Cyclic adenosine monophosphate levels were significantly higher in rolipram-reperfused lungs retrieved 120 minutes after death in both oxygen-ventilated (p<0.01) and nonventilated (p<0.01) lungs.

CONCLUSIONS

In lungs from nonventilated, circulation-arrested donors, reperfusion with rolipram reduces the ischemia-reperfusion injury that may be due to intracellular cyclic adenosine monophosphate. Alteration of perfusate may have an impact on capillary leak caused by antecedent ischemia. Thus, rolipram may be a useful adjunct in the preservation of donor lungs retrieved after death.

Identification of mammaglobin B, a novel member of the uteroglobin gene family

In this report, we have identified, sequenced, and characterized the expression pattern of a novel human gene, mammaglobin B. Mammaglobin B (MGB2) is highly homologous to mammaglobin (MGB1), a previously characterized human gene whose expression is limited to the mammary epithelium and frequently up-regulated in human breast cancer cells. Based upon amino acid sequence similarities, both mammaglobin and mammaglobin B may be considered members of a larger, mammalian multigene family that includes rabbit uteroglobin, human Clara Cell 10-kDa protein (CC10), and the multimeric rat prostatein protein. Together with the human CC10 gene, mammaglobin and mammaglobin B are closely linked on human chromosome 11q13. However, despite their primary sequence similarity and close chromosomal proximity, the expression of mammaglobin and mammaglobin B is nonconcordant in both nonmalignant and neoplastic tissue.

When does the lung die? Kfc, cell viability, and adenine nucleotide changes in the circulation-arrested rat lung

Lungs harvested from cadaveric circulation-arrested donors may increase the donor pool for lung transplantation. To determine the degree and time course of ischemia-reperfusion injury, we evaluated the effect of O2 ventilation on capillary permeability [capillary filtration coefficient (Kfc)], cell viability, and total adenine nucleotide (TAN) levels in in situ circulation-arrested rat lungs. Kfc increased with increasing postmortem ischemic time (r = 0.88). Lungs ventilated with O2 1 h postmortem had similar Kfc and wet-to-dry ratios as controls. Nonventilated lungs had threefold (P < 0.05) and sevenfold (P < 0.0001) increases in Kfc at 30 and 60 min postmortem compared with controls. Cell viability decreased in all groups except for 30-min postmortem O2-ventilated lungs. TAN levels decreased with increasing ischemic time, particularly in nonventilated lungs. Loss of adenine nucleotides correlated with increasing Kfc values (r = 0.76). This study indicates that lungs retrieved 1 h postmortem may have normal Kfc with preharvest O2 ventilation. The relationship between Kfc and TAN suggests that vascular permeability may be related to lung TAN levels.

A snapshot of tuberculosis in urban Minnesota

We reviewed the records of all 66 cases of tuberculosis in St. Paul between 1986 and 1989. Two-thirds of the patients were foreign born. Some of these patients experienced problems in adherence to therapy because of cultural barriers. Resistance of the organism to antituberculosis medications was also a significant problem.

Intracardiac surgery in pregnant women

A survey of members of The Society of Thoracic Surgeons was undertaken to obtain information on experiences with cardiac operations in pregnant women. The experiences reported were highly successful, with only 1 maternal death in 68 procedures utilizing cardiopulmonary bypass and more than 80% survival of fetuses. Cardiac operations in pregnant patients probably can be made safer by avoidance of perfusion hypothermia and by use of fetal heart and uterine monitoring. When valve replacement is necessary, use of biological valves is recommended to avoid the necessity for anticoagulation.

Pulmonary venous-bronchial fistula following left atrial pressure line insertion: iatrogenic cause of air embolism following cardiac surgery

A 65-year-old patient sustained massive air embolism after the needle used for left atrial pressure line insertion punctured the posterior wall of the superior pulmonary vein, entering the middle lobe bronchus and causing a pulmonary venous-bronchus fistula. This is an apparently heretofore unrecognized potential cause of massive air embolism following cardiac surgery.

False aneurysm of aorta secondary to partial occlusion clamp injury: diagnosis by nuclear flow study

A 72-year-old woman presented 12 months postaortic valve replacement with a false aneurysm near the aortic cannulation site. The diagnosis was suspected from clinical findings and confirmed by a nuclear flow study. The patient refused surgery and died shortly afterward. At autopsy, a smooth-walled 1 cm defect adjacent to the cannulation site (presumably related to injury from a partial occlusion clamp) was found; this would have been easily reparable with surgery.

Medium-term follow-up of the Ionescu-Shiley heterograft valve

Utilizing a questionnaire specifically designed to uncover potential thromboembolic episodes, we personally interviewed 97 patients who underwent valve replacement with the Ionescu-Shiley valve between January, 1977, and June, 1980. In both the aortic and mitral positions, the attrition rate after the first year was low; cumulative survival at 3 to 4 years was 78% (aortic) and 61% (mitral). None of the deaths were attributed to primary valve failure. Patients with aortic prostheses, none of whom were anticoagulated, had a cumulative thromboembolism-free rate of 94% at 3 to 4 years. Patients with mitral prostheses had a thromboembolism-free rate of 71% at 3 to 4 years with 80% of the episodes occurring in patients in atrial fibrillation. Most emboli produced only transient symptoms, and only 1 patient has residual impairment. The Ionescu-Shiley valve performs well in the early years after valve replacement. Anticoagulation should be strongly considered for patients with mitral prostheses who are in atrial fibrillation.

Cortisol and antidiuretic hormone responses to stress in cardiac surgical patients

The hormonal responses to anaesthesia and cardiac surgery were studied in patients undergoing valve or coronary bypass surgery. Marked increases in antidiuretic hormone levels as a result of surgical stress were seen, and were of approximately equal magnitude in both groups. Although both groups also showed marked increases in plasma cortisol levels in response to operations, this response appeared to be relatively blunted in valve surgery patients, especially at the end of operation and in the intensive care unit. This blunted cortisol response may be a manifestation of exhaustion of adrenocortical reserves in valvular surgical patients whose sympathoadrenal system has already been chronically stimulated by a low output state. The important role of the neuroendocrine system in maintaining homeostasis postoperatively has long been recognized; this relative cortisol deficiency may be aetiologically related to poor postoperative recovery in critically ill valvular surgery patients.

Hemodynamic performance of the Ionescu-Shiley valve prosthesis

The hemodynamic performance of the Ionescu-Shiley bovine heterograft valve has been evaluated by intraoperative measurement of transvalvular gradients and cardiac outputs. Effective orifice areas (EOAs) were calculated and the data compared to those obtained by other investigators for other prostheses. In the aortic position, each valve, from 19 to 31 mm external diameter, produced a pressure gradient; mean EOA increased with increasing valve size, so that small (19 to 23 mm) valves were moderately stenotic and larger valves were only mildly stenotic. The presence of a mitral prosthesis produced larger transaortic valve gradients, probably as a result of aortic outflow obstruction by the mitral prosthesis. The Ionescu valve appears to be hemodynamically superior to other biological valves in the aortic position and comparable to most mechanical prostheses, although the data for comparison are scant. Each mitral valve produced a pressure gradient and, on the average, larger (29 mm) valves performed no better than smaller (25 mm). Mean EOAs for each valve size (25 to 29 mm) were adequate to provide satisfactory hemodynamics comparable to other available prosthetic valves. Mild obstruction of the left ventricular outflow by the prosthetic struts was seen to be related to the distance between ventricular septum and the struts. Most currently available prostheses seem to provide similar hemodynamics in the mitral position, and considerations such as thrombogenicity and durability may be relatively more important in the choice of a mitral valve substitute than in the choice of an aortic valve substitute.

Pulsatile cardiopulmonary bypass: failure to influence hemodynamics or hormones

In a randomized trial of pulsatile vs nonpulsatile cardiopulmonary bypass for coronary artery surgery, we studied hemodynamic and hormonal responses. Anesthesia did not produce a response but, from the time of the incision, cortisol and antidiuretic hormone levels and plasma renin activity all increased. Cortisol levels continued to rise after surgery, whereas the other began to fall. Systemic vascular resistance fell dramatically during cardiopulmonary bypass but rapidly rose after bypass with a reciprocal change in cardiac index. We did not see the changes ascribed to nonpulsatile bypass by others. There ws no difference between our pulsatile and nonpulsatile cases. High-flow cardiopulmonary bypass, vasodilating inhalation anesthesia and continuation of Inderal therapy may account for our results.

Application of transesophageal echocardiography to continuous intraoperative monitoring of left ventricular performance

Transesophageal M mode echocardiography was used for continuous monitoring of left ventricular dimensions in 21 patients (11 with valvular and 10 with coronary heart disease) undergoing open heart surgery. Echocardiograms were recorded in six stages of the procedure and simultaneous measurements of cardiac output (with dye dilution) and atrial pressures were made. Measurements of left ventricular diameters with the transesophageal technique correlated excellently with the corresponding measurements obtained with the standard parasternal method. In patients with volume overload, surgical correction was accompanied by a decrease in diastolic dimension, velocity of circumferential fiber shortening, mid wall stress and end-diastolic stiffness, and an increase in cardiac output. Pericardial and chest wall closures generally caused a significant decrease in cardiac output, and correlated with a decrease in diastolic diameter and an increase in the stiffness constant of the left ventricle. Thus, the decrease in cardiac output may have been due to decreased distensibility of the ventricular cavity secondary to mechanical restriction by the pericardium and chest wall. Pericardial opening caused a significant delay in septal motion that was reversed by closing the pericardium. This study confirms the validity of transesophageal echocardiography and its usefulness in monitoring changes in ventricular function during cardiac surgery.

Noncardiogenic pulmonary edema and peripheral vascular collapse following cardiopulmonary bypass: rare protamine reaction?

Four instances of severe anaphylactoid reaction occurring subsequent to cardiopulmonary bypass are described. These catastrophic reactions, from which 2 patients died, took place approximately an hour following administration of protamine and were characterized by marked peripheral vasodilatation, loss of capillary membrane integrity, and fulminant noncardiogenic pulmonary edema. Primary cardiac depression was not evident. We hypothesize that protamine was the causative agent in these unusually severe reactions. Differential diagnosis from other causes of acute cardiorespiratory dysfunction depended on early assessment of pulmonary artery and left ventricular filling pressures, cardiac output, respiratory mechanics, and arterial blood gases. Therapy was difficult; success in 1 of the patients seemed to have been effected in part by prompt administration of high-dose corticosteroids and maintenance of peripheral vascular tone with an alpha-adrenergic agonist.

beta-Blockade therapy for supraventricular tachyarrhythmias after coronary surgery: a propranolol withdrawal syndrome?

A high incidence of cardiac arrhythmias and hypertension has been noted after coronary artery bypass surgery in patients previously treated with oral propranolol. Forty-two patients undergoing coronary bypass surgery had propranolol withdrawal 10 hours before surgery and were randomized into a group treated with propranolol immediately postoperatively, and a nontreatment group. Patients treated with prophylactic propranolol had a significantly lower incidence of postoperative supraventricular arrhythmias compared to patints who received no prophylaxis. All the arrhythmias responded rapidly to 1 mg of intravenous propranolol therapy, whether it was used as a primary treatment or as a supplement to prophylactic propranolol. The findings suggest that (1) there is a high incidence of supraventricular arrhythmias and sinus tachycardia after coronary artery bypass which might reflect an abrupt propranolol withdrawal, and (2) that perioperative prophylactic or supplementary propranolol therapy will successfully prevent or treat most of these arrhythmias.

Dynamic aspects of acute mitral regurgitation: effects of ventricular volume, pressure and contractility on the effective regurgitant orifice area

The dynamics of acute mitral regurgitation were studied in six open-chest dogs in whom a portion of the anterior leaflet was excised. Phasic mitral and aortic flows were measured electromagnetically and left ventricular filling volume, regurgitant volume (RV) and forward stroke volume (SV) were calculated. The systolic pressure gradient (SPG) between the left ventricle (LV) and left atrium (LA) was obtained from high-fidelity pressure transducers. The effective mitral regurgitant orifice area (MRA) was calculated from the hydraulic equation of Gorlin. Volume infusion resulted in significant increases in both left atrial and left ventricular pressures; thus, the SPG was unchanged and the increase in RV was due primarily to the increase in MRA. Angiotensin infused to raise arterial pressure resulted in greater increments in left ventricular than left atrial pressure, so that SPG rose significantly. The increase in RV was due to increases in both MRA and SPG. Norepinephrine infusion increased systolic left ventricular pressure and SPG, while left ventricular end-diastolic pressure and left atrial pressure diminished. Despite a significant increase in SPG, RV did not increase, due to a substantial decrease in MRA. Thus, angiotensin and volume infusion induced a substantial increase in regurgitation due to the increase in MRA, while augmentation of contractility after norepinephrine infusion resulted in a decrease in regurgitation through reduction of MRA. These findings support the clinical view that maintaining a small LV with sustained myocardial contractility will reduce mitral regurgitation. Alternatively, left ventricular dilatation can enhance mitral regurgitation by increasing the effective regurgitant orifice independent of SPG.

Mechanism of reduction of mitral regurgitation with vasodilator therapy

Acute mitral regurgitation was produced in six open chest dogs by excising a portion of the anterior valve leaflet. Electromagnetic flow probes were placed in the left atrium around the mitral anulus and in the ascending aorta to determine phasic left ventricular filling volume, regurgitant volume and stroke volume. The systolic pressure gradient was calculated from simultaneously measured high fidelity left atrial and left ventricular pressures. The effective mitral regurgitant orifice area was calculated from Gorlin's hydraulic equation. Infusion of nitroprusside resulted in a significant reduction in mitral regurgitation. No significant change occurred in the systolic pressure gradient between the left ventricle and the left atrium because both peak left ventricular pressure and left atrial pressure were reduced. The reduction of mitral regurgitation was largely due to reduction in the size of the mitral regurgitant orifice. Reduction of ventricular volume rather than the traditional concept of reduction of impedance of left ventricular ejection may explain the effects of vasodilators in reducing mitral regurgitation.

Surgery for mitral valve endocarditis

The records of 20 patients who underwent mitral valve replacement for complications of bacterial endocarditis were reviewed. Although the indications for surgery were the same as those for patients with aortic endocarditis, major emboli (cerebral, coronary or retinal) prompted surgery in 8 of 20 patients, a much higher incidence than reported for surgery in aortic valve endocarditis. Eighteen of the patients had mitral regurgitation; 14 of these had severe congestive heart failure, but the development of congestive failure tended to be more insidious than in patients with aortic endocarditis. Continued septicemia despite appropriate antibiotics was the least common indication for surgery. Sixteen of the 20 patients were salvaged by surgery, although some had major residual deficits, related mainly to preoperative emboli. These results are a marked improvement in the expected 90-100 percent mortality rate for patients with these complications of endocarditis. The main reason for a poor result following surgery was temporization leading to continued deterioration of vital functions preoperatively. Reinfection of the prosthesis did not occur, and we do not consider duration of preoperative antibiotic therapy an important factor in the decision to perform surgery.

In vitro hydrodynamic comparison of mitral valve prostheses at high flow rates

A pulse duplicator system for evaluating the hemodynamic performance of mitral prostheses is described. Under conditions stimulating normal resting physiology, all valves tested had measurable but acceptably small pressure drops. Under conditions simulating exercise, all were moderately to severely stenotic. Valves with nearly equal mounting diameters were compared. The Hancock, Beall, and Starr-Edwards valves (Group A) were found to be significantly more stenotic than the Björk-Shiley, Cutter-Cooley, Ionescu-Shiley, and Lillehei-Kaster valves (Group B). In the 29 to 30 mm. mounting diameter size at cardiac outputs of 5 and 9 L. per minute, Group A had average pressure drops of 3.2 and 10.5 mm. Hg and Group B, pressure drops of 1.6 and 5.3 mm. Hg, respectively. In the 24 to 26 mm. mounting diameter size, at cardiac outputs of 9 L. per minute, all the valves had critically large pressure drops (9 to 17.6 mm. Hg). The standard Gorlin formula is inappropriate for computing the orifice area of prosthetic valves. The discharge coefficient for a valve (a measure of how well the valve uses its primary flow area) and a performance index (a measure of how well the valve uses its mounting area) have been computed from a knowledge of the orifice size, without the necessity of assuming a value for the discharge coefficient required by the Gorlin formula. The biological valves (Hancock and Ionescu-Shiley) provide an efficient orifice for fluid flow at the free leaflet margins and have large discharge coefficients. On the basis of the fluid dynamic equation of motion, steady flow, root mean square (RMS) flow, and peak flow, combined with the appropriate transvalvular gradients, were all shown to yield equally accurate characterizations of valvular hydrodynamic performance. Mean flow, unfortunately the only value obtainable clinically, yielded effective orifice areas 10 percent smaller than either of the other three flow values.

Infected aortic bifurcation grafts: experience with fourteen patients

The experience with 14 patients with infected aortic bifurcation grafts has been reviewed. Factors which appeared to predispose to infection in 11 patients included "re-do" operations, concomitant cholecystectomy or gastrostomy, and ruptured abdominal aneurysm. A mixture of gastrointestinal organisms was responsible for the infections. The pathogenesis, presentation, and treatment varied according to whether the proximal or distal anastomosis was involved or not. Aortoduodenal communications were present in five patients; they presented with gastrointestinal bleeding or septicemia. One patient survived as a result of early, aggressive surgical therapy. Infection presented at the distal anastomosis in nine patients, either as groin abscess or false aneurysm. Conservative therapy failed in the majority of patients but apparently was successful in three of five patients in whom infection did not involve the intra-abdominal portion of the graft. When infection does involve the intra-abdominal portion of the graft, then the graft must be excised also. Revascularization often can be accomplished with extra-anatomic bypasses of prosthesis or autogenous material, depending on the characteristics of the individual patient. Regardless of the mode of presentation or the site of infection, the early institution of judicious surgical management offers the best chance of success in these patients, and temporization usually leads to failure.

Transaxillary minithoracotomy: the optimal approach for certain pulmonary and mediastinal lesions

This report concerns the use of transaxillary thoracotomy for a variety of pulmonary, pleural, and mediastinal conditions in 50 patients. Primary and metastatic carcinomas, pneumothoraces, and benign lesions such as bronchogenic cysts and neurogenic tumors can be identified, evaluated, and treated with confidence. Reduced postoperative pain and morbidity, rapid return of arm and shoulder movements, reduced hospital stay, and excellent cosmetic result are among the advantages of this approach when compared with the usual posterolateral thoracotomy.

Multiple pulmonary leiomyomatous hamartomas in women

A rare case of multiple pulmonary leiomyomatous hamartomas is described and seven previously reported cases are reviewed. The pathological and clinical features of this lesion, which is benign and occurs in middle-aged women, are unique; a conservative approach following the establishment of diagnosis is recommended.

Congenital esophagobronchial fistula in a 62-year-old woman

A 62-year-old woman had symptoms of cough provoked by ingestion of liquids and radiologic changes compatible with repeated bouts of aspiration pneumonitis. A left bronchoesophageal fistula was easily demonstrated by barium esophagogram and fiberoptic bronchoscopy. Division of the fistula resulted in immediate disappearance of the symptoms, gradual resolution of the radiologic abnormalities, and marked improvement in the results of pulmonary function tests. The fistula appeared to be of congenital origin, but the reason that symptoms developed so late in life remains obscure.