A prospective randomized trial of arginine vasopressin in the treatment of vasodilatory shock after left ventricular assist device placement

BACKGROUND

Vasodilatory shock requiring catecholamine pressors occurs in some patients following cardiopulmonary bypass. Prompted by a clinical observation, we investigated the use of vasopressin as a treatment for this syndrome in a randomized, controlled trial.

METHODS AND RESULTS

Patients undergoing placement of a left ventricular assist device (n=23) were evaluated for post-bypass vasodilatory shock requiring catecholamine pressors, and consecutive eligible subjects (n=10) were evenly randomized to blinded intravenous vasopressin or saline placebo. Vasopressin (0.1 U/min) increased mean arterial pressure (57+/-4 to 84+/-2 mm Hg, P<.001) and systemic vascular resistance (813+/-113 to 1188+/-87 dyne-s/cm5, P<.001), with decreased norepinephrine administration. There was no significant response to saline, but in three subjects who crossed over, blinded vasopressin increased mean arterial pressure (69+/-8 to 93+/-4 mm Hg) and systemic vascular resistance (898+/-88 to 1443+/-72 dyne-s/cm5) with decreased norepinephrine administration. Plasma vasopressin concentrations prior to randomization clustered in two groups: one (n=5) with concentrations inappropriately low for the degree of hypotension (8.4+/-2.1 pg/mL) and a second (n=3) with moderately elevated levels (33.7+/-1.6 pg/mL); vasopressin increased mean arterial pressure in the low vasopressin group from 57+/-4 to 85+/-2 mm Hg (P<.01) and in the high vasopressin group from 68+/-8 to 86+/-4 mm Hg.

CONCLUSIONS

Vasopressin is an effective pressor in vasodilatory shock after cardiopulmonary bypass. An absolute vasopressin deficiency was observed in the majority of patients, but all subjects responded to vasopressin administration.

Experimental Leptospira borgpetersenii serovar hardjo infection of pregnant cattle

OBJECTIVE

To observe the effect upon the foetus of experimental infection of pregnant cattle with Leptospira borgpetersenii serovar hardjo.

DESIGN

A disease transmission study using pregnant cattle.

PROCEDURE

Fourteen heifers serologically negative to L hardjo were artificially inseminated and later challenged with a north-Queensland isolate of L hardjo by conjunctival inoculation. The heifers were serologically monitored and their urine examined for the presence of leptospires using culture and fluorescent-antibody tests at appropriate intervals. Elective caesarean sections were performed on pregnant heifers at 6.5 weeks after the challenge. Foetuses were examined using serological, histopathological, microbiological and fluorescent-antibody tests.

RESULTS

Ten of the heifers became pregnant, but three subsequently aborted before challenge. After challenge, all 14 heifers seroconverted and L hardjo was isolated from the urine of 6 of the 7 pregnant heifers. No evidence of foetal L hardjo infection was detected. Two of the foetuses had histopatho-logical lesions consistent with Neospora sp infection.

CONCLUSION

It is likely that the isolate of L hardjo used in this study does not normally infect the foetus. Neospora sp may be a more significant cause of bovine reproductive wastage.

Amoxycillin as an alternative to dihydrostreptomycin sulphate for treating cattle infected with Leptospira borgpetersenii serovar hardjo

OBJECTIVE

To assess the effect of amoxycillin treatment on urinary excretion of leptospires from cattle infected with Leptospira borgpetersenii serovar hardjo.

DESIGN

A chemotherapy trial with controls.

PROCEDURE

Fourteen heifers serologically negative to L hardjo were inoculated with L hardjo via the conjunctival route and assessed for evidence of infection by serological, fluorescent antibody and microbiological tests. Two injections (48 h apart) of amoxycillin at a dose of 15 mg/kg were administered intramuscularly to seven heifers 6.5 weeks after infection; the remaining heifers acted as untreated controls. Later, these seven control group heifers were treated with a single dose of amoxycillin (15 mg/kg). Samples of urine were collected before and after amoxycillin treatments; kidneys were collected at slaughter, and examined by fluorescent antibody test and microbiological culture.

RESULTS

Leptospires were isolated from the urine of 11 of 14 heifers inoculated with L hardjo. After treatment of six of these with two injections of amoxycillin, leptospires were not isolated. Of the controls, four of the five initially leptospiruric heifers continued to shed leptospires; after a single injection of amoxycillin, no leptospires were detected in the kidneys of these four.

CONCLUSION

Amoxycillin may be an acceptable alternative to dihydrostreptomycin sulphate for the treatment of cattle infected with L hardjo.

Late pulmonary venous complications after lung transplantation

Although abnormalities of the pulmonary venous anastomosis in the early postoperative period after lung transplantation have been reported from several centers, late complications related to the pulmonary venous anastomosis have not been described. In the present study, we describe the clinical and transesophageal echocardiographic findings of pulmonary vein anastomotic complications in two patients at 1.9 and 2.3 years after lung transplantation. Both pulmonary venous abnormalities, stenosis in the first instance and thrombosis in the second instance, impaired venous outflow on the affected side causing unilateral edema and pleural effusion. Pulmonary venous abnormalities late after lung transplantation can mimic allograft rejection, opportunistic infection, or heart failure and are best diagnosed by transesophageal echocardiography.

Histologic analysis of transmyocardial channels: comparison of CO2 and holmium:YAG lasers

BACKGROUND

Transmyocardial laser revascularization using different lasers is being tested in the treatment of refractory angina. We conducted comparative analysis of the acute and chronic myocardial effects of these different lasers.

METHODS

Transmyocardial channels were made in normal dog hearts with either a holmium:yttrium-aluminum garnet or a CO2 laser. Channels were examined histologically 6 to 24 hours, 2 to 3 weeks, and 6 weeks after creation.

RESULTS

Regardless of the laser source, the channels were occluded by thrombus within 6 to 24 hours. Subsequently, organization and neovascularization of the channel region occurred. Thermoacoustic damage was initially greater with the holmium:yttrium-aluminum garnet laser, but the channel appearances were indistinguishable from those made with the CO2 laser by 6 weeks.

CONCLUSIONS

Histologically, the myocardial effects of the CO2 and holmium:yttrium-aluminum garnet lasers are similar and differ predominantly in the amount of acute thermoacoustic injury. Channels are rapidly occluded by thrombus and are replaced by neovascularized collagen. This suggests that the physiologic effects of these two lasers may be similar and that mechanisms other than blood flow through chronic patent channels should be considered as contributing to the clinical benefits observed with this procedure.

Use of positron emission tomography to study the dynamics of psychostimulant-induced dopamine release

Microdialysis studies have shown that psychostimulants act through a common neurochemical mechanism of elevating synaptic dopamine content in the mesocorticolimbic dopaminergic system. However, little information is available regarding the dynamics of the interaction between the elevated synaptic dopamine levels induced by a psychostimulant and postsynaptic dopamine receptors. The goal of the current investigation was to determine if positron emission tomography (PET) studies using the dopamine D2-selective radioligand [18F]4'-fluoroclebopride ([18F]FCP) could be used to measure synaptic dopamine levels. Rhesus monkeys were used because our previous studies revealed that [18F]FCP has a low test/retest variability in this species. Under control conditions, [18F]FCP had a high uptake and slow rate of washout from the basal ganglia, a region of brain that expresses a high density of D2 receptors, reaching kinetic equilibrium at approximately 40 min. Challenge studies, each separated by at least 1 month, were conducted by administering an intravenous dose of (-)cocaine, d-amphetamine, methylphenidate, or d-methamphetamine (1.0 mg/kg) at 40 min post-IV injection of a no-carrier-added dose of [18F]FCP. In each case, the psychostimulant caused an increase in the rate of washout of [18F]FCP from the basal ganglia. Methamphetamine and amphetamine had more pronounced effects on the washout kinetics of [18F]FCP relative to cocaine and methylphenidate, a result that is consistent with the ability of each drug to elevate synaptic dopamine levels. Our results indicate that challenge studies with [18F]FCP may be a useful technique for studying the dynamics of the interaction between psychostimulant-induced increases in synaptic dopamine and postsynaptic D2 receptors.

An overview of plague in the United States and a report of investigations of two human cases in Kern county, California, 1995

Plague was confirmed in the United States from nine western states during 1995. Evidence of Yersinia pestis infection was identified in 28 species of wild or domestic mammals. Thirteen of the plague positive species were wild rodents; 15 were predators/carnivores. Yersinia pestis was isolated from eight species of fleas. Seven confirmed cases of human plague were reported in 1995 (New Mexico 3; California 2; Arizona and Oregon 1 each). Five of the seven cases were bubonic; one was septicemic and one a fatal pneumonic case. Months of onset ranged from March through August. In California, during 1995, plague was recorded from 15 of the 58 counties. Over 1,500 animals were tested, of which 208 were plague positive. These included 144 rodents and 64 predators/carnivores. Two confirmed human cases (one bubonic and one fatal pneumonic) occurred, both in Kern County. Case No. 1 was reported from the town of Tehachapi. The patient, a 23 year-old male resident, died following a diagnosis of plague pneumonia. The patient's source of plague infection could not be determined precisely. Field investigations revealed an extensive plague epizootic surrounding Tehachapi, an area of approximately 500-600 square miles (800-970 square kilometers). Case No. 2 was a 57 year-old female diagnosed with bubonic plague; she was placed on an antibiotic regimen and subsequently recovered. The patient lives approximately 20 miles (32 km) north of Tehachapi. Field investigations revealed evidence of a plague epizootic in the vicinity of the victim's residence and adjacent areas. Overall results of the joint field investigations throughout the entire Kern county area revealed a high rate of plague positive animals. Of the numerous samples submitted, 48 non-human samples were plague positive.

Cockroach: the omnivorous scavenger. Potential misinterpretation of postmortem injuries

Interpretation of postmortem injuries, including their differentiation from those produced antemortem, may be difficult even for experienced forensic pathologists. A variety of animals or insects residing in the death environment may alter the appearance of the deceased. Dictyoptera blattaria (the cockroach) is common in the residential setting. Three cases of sudden and unexpected infant death are presented in which postmortem injuries inflicted by cockroaches initially raised concern of nonaccidental injury. The true nature of the lesions was not recognized by the people at the death scene and, in one case, observation of neck injuries raised suspicion of possible strangulation. In another, the lesions were thought to be burns of different ages. Cockroaches are omnivorous scavengers that devour keratin. They will bite human flesh in both the living and dead with resultant injury. Recognition of cockroach bites will help in the evaluation of injuries discovered during child death investigations.

The effects of psyllium hydrophilic mucilloid on diarrhea in enterally fed patients

OBJECTIVE

To investigate the efficacy of psyllium hydrophilic mucilloid (PHM) for prevention of diarrhea and to compare methods of PHM delivery.

DESIGN

Experimental.

SETTING

University-affiliated Department of Veterans Affairs Medical Center.

SUBJECTS

Sixty patients from medical-surgical and intensive care units who received newly initiated enteral feeding via feeding tube.

OUTCOME MEASURES

Diarrhea, stool frequency and consistency, and feeding tube obstruction.

INTERVENTION

Receipt of PHM (7 gm, twice-daily) added to continuous feeding or given as a bolus with intermittent feeding, or receipt of No PHM for 7 days after initiation of enteral feeding.

RESULTS

Fifteen subjects (25%) developed diarrhea (defined as 3 or more liquid stools per day, or 2 or more liquid stools on successive days). There were no significant differences in incidence of diarrhea or percentage of days of diarrhea between subjects who did and did not receive PHM. However, subjects who received PHM in their continuous feedings had a significantly higher number of gelatinous stools, and the combined PHM groups had a significantly lower number of liquid stools and a higher number of normal stools than did subjects who did not receive PHM. For the combined PHM groups, there was a 12% incidence of small-bore feeding tube occlusion--requiring replacement.

CONCLUSIONS

Further study with a larger sample is necessary to evaluate trends found in this pilot study and to determine PHM efficacy for prevention of diarrhea. PHM administration may result in small-bore feeding tube obstruction, and thus requires adequate dilution and close monitoring.

Physiology, histology, and 2-week morphology of acute transmyocardial channels made with a CO2 laser

BACKGROUND

Transmyocardial revascularization with a CO2 laser appears to improve symptoms in patients with refractory angina. However, it remains controversial as to whether blood flow through the channels is the mechanism of benefit, especially in the acute setting.

METHODS AND RESULTS

Three protocols were used to test whether blood flows through transmyocardial CO2 laser revascularization channels. First, channels were made in excised, cross-perfused dog hearts (n = 5) using a CO2 laser (The Heart Laser; PLC Systems Inc, Milford, MA; 40 J/pulse) followed by ligation of the proximal left anterior descending coronary artery. Colored microspheres injected into the left ventricular chamber failed to detect any significant transmyocardial blood flow. In the second protocol (n = 4), laser channels were created in the left anterior descending artery territory, the left anterior descending artery was ligated, and the hearts were excised after 24 hours. Triphenyltetrazolium chloride staining revealed that no viable myocardium was detected around the laser channels in the ischemic myocardium. Finally, channels examined 2 weeks after creation in normal (n = 6) or ischemic (n = 4) myocardium did not maintain their original caliber but were invaded by granulation tissue, which included a large amount of smaller vascular spaces and vessels of various sizes.

CONCLUSIONS

Transmyocardial laser revascularization channels made with this CO2 laser did not provide acute myocardial perfusion or preserve myocardial viability in the face of acute ischemia. Channel morphology changes dramatically within the first 2 weeks. To the degree that these findings pertain to human myocardium, the results suggest that transmyocardial blood flow may not be the mechanism of benefit of this procedure, particularly in the acute setting.

Evidence for the microbial basis of a chemoautotrophic invertebrate community at a whale fall on the deep seafloor: bone-colonizing bacteria and invertebrate endosymbionts

To explore the microbial basis for a remarkable macrofaunal community at the site of a whale skeleton on the seafloor of the Santa Catalina Basin, we obtained samples of whale bone, bone-colonizing invertebrates, microbial mats, and the dominant fauna in the adjacent sulfide-rich sediments during Alvin expeditions in 1988 and 1991. Invertebrate tissues were examined by transmission electron microscopy (TEM) and mats and bone-penetrating bacteria by epifluorescence microscopy (EM). Tissues from the dominant bivalve Vesicomya c.f. gigas, the mytilid mussel Idasola washingtonia, and selected gastropods and limpets were also assayed chemically for enzymes diagnostic of sulfur- and methane-based chemoautotrophy and for stable carbon isotopic composition. Results of all analyses were consistent with dominant sulfur-based endosymbioses in the clam and mussel (the first record of endosymbiosis in the genus Idasola) and the general absence of methane symbioses at the site, strengthening the analogy of the whale-skeleton faunal community to those known from distant Pacific hydrothermal vent sites. Examples of minor endosymbionts, either nitrifying or methanotrophic cells according to internal membrane structures by TEM, raised the possibility of a supplemental mode of nutrition to the clam, or means to remove ammonia in the gill tissue, in the event of significant changes in the chemical environment.

Imaging of cholinergic terminals using the radiotracer [18F](+)-4-fluorobenzyltrozamicol: in vitro binding studies and positron emission tomography studies in nonhuman primates

The goal of the present set of studies was to characterize the in vitro binding properties and in vivo tissue kinetics for the vesicular acetylcholine transporter (VAcChT) radiotracer, [18F](+)-4-fluorobenzyltrozamicol ([18F](+)-FBT). In vitro binding studies were conducted in order to determine the affinity of the (+)- and (-)-stereoisomers of FBT for the VAcChT as well as sigma (sigma 1 and sigma 2) receptors. (+)-FBT was found to have a high affinity (Ki = 0.22 nM) for the VAcChT and lower affinities for sigma 1 (21.6 nM) and sigma 2 (35.9 nM) receptors, whereas (-)-FBT had similar affinities for the VAcChT and sigma 1 receptors (approximately 20 nM) and a lower affinity for sigma 2 (110 nM) receptors. PET imaging studies were conducted in rhesus monkeys (n = 3) with [18F](+)-FBT. [18F](+)-FBT was found to have a high accumulation and slow rate of washout from the basal ganglia, which is consistent with the labeling of cholinergic interneurons in this brain region. [18F](+)-FBT also displayed reversible binding kinetics during the 3 h time course of PET and produced radiolabeled metabolites that did not cross the blood-brain barrier. The results from the current in vitro and in vivo studies indicate that [18F](+)-FBT is a promising ligand for studying cholinergic terminal density, with PET, via the VAcChT.

Assessment of transmyocardial perfusion in alligator hearts

BACKGROUND

Techniques for achieving myocardial perfusion directly from the left ventricular chamber are currently under investigation. Although originally based on the anatomy of reptilian hearts, which are rich in transmural channels and reported to have a poorly developed coronary vasculature, the blood flow capacity of a transmyocardial blood supply has not been studied in these hearts. With the ultimate goal of providing insight into the potential for achieving transmyocardial perfusion in human hearts, we studied the relative contribution of transmyocardial and coronary perfusion in alligator hearts.

METHODS AND RESULTS

After explanation from six American alligators, the left ventricle was instrumented, and coronary arteries were perfused with oxygenated physiological solution. Using microspheres to estimate regional myocardial perfusion in the beating hearts, we show that although the epicardium was well perfused by the coronary arteries (0.20 +/- 0.08 versus 0.07 +/- 0.01 mL.min-1.g-1 owing to flow from the ventricular chamber), a significant proportion of endocardial perfusion was from the ventricular chamber (0.21 +/- 0.07 mL.min-1.g-1 from the left ventricle versus 0.13 +/- 0.04 mL.min-1.g-1 from coronary arteries).

CONCLUSIONS

A significant amount of direct transmyocardial perfusion is present in alligator hearts. The conditions that apparently permit this situation in reptilian hearts are reviewed, and their implications for aiding in the optimization of techniques for achieving transmyocardial flow in humans are discussed.

Self-hypnosis reduces anxiety following coronary artery bypass surgery. A prospective, randomized trial

OBJECTIVE

The role of complementary medicine techniques has generated increasing interest in today's society. The purpose of our study was to evaluate the effects of one technique, self-hypnosis, and its role in coronary artery bypass surgery. We hypotesize that self-hypnosis relaxation techniques will have a positive effect on the patient's mental and physical condition following coronary artery bypass surgery.

EXPERIMENTAL DESIGN

A prospective, randomized trial was conducted. Patients were followed beginning one day prior to surgery until the time of discharge from the hospital.

SETTING

The study was conducted at Columbia Presbyterian Medical Center, a large tertiary care teaching institution.

PATIENTS

All patients undergoing first-time elective coronary artery bypass surgery were eligible. A total of 32 patients were randomized into two groups.

INTERVENTIONS

The study group was taught self-hypnosis relaxation techniques preoperatively, with no therapy in the control group.

MEASURES

Outcome variables studied included anesthetic requirements, operative parameters, postoperative pain medication requirements, quality of life, hospital stay, major morbidity and mortality.

RESULTS

Patients who were taught self-hypnosis relaxation techniques were significantly more relaxed postoperatively compared to the control group (p=0.032). Pain medication requirements were also significantly less in patients practising the self-hypnosis relaxation techniques that those who were noncompliant (p=0.046). No differences were noted in intraoperative parameters, morbidity or mortality.

CONCLUSION

This study demonstrates the beneficial effects self-hypnosis relaxation techniques on patients undergoing coronary artery bypass surgery. It also provides a framework to study complementary techniques and the limitations encountered.

A multicenter, randomized, double-blind, placebo-controlled trial of influenza immunization in multiple sclerosis

We determined the effect of influenza vaccine in patients with relapsing/remitting MS. Considerable controversy surrounds the question of whether to administer influenza vaccines to MS patients. Prevention of a febrile viral illness is clearly desirable in MS, and previous studies suggest that immunization is safe. Despite this, many clinicians avoid vaccination because they fear precipitating an MS exacerbation. We conducted a multicenter, prospective, randomized, double-blind trial of influenza immunization in patients with relapsing/remitting MS. In the autumn of 1993, 104 patients at five MS centers received either standard influenza vaccine or placebo. Patients were followed for 6 months for evaluation of neurologic status and the occurrence of influenza. Influenza was operationally defined as fever > or = 38 degrees C in the presence of coryza, cough, or sore throat at a time when the disease was present in the community. Attacks were defined in the standard manner, requiring objective change in the examination. Patients were examined at 4 weeks and 6 months after inoculation and were contacted by telephone at 1 week and 3 months. They were also examined at times of possible attacks but not when they were sick with flu-like illness. Three vaccine patients and two placebo patients experienced attacks within 28 days of vaccine (no significant difference). Exacerbation rates in the first month for both groups were equal to or less than expected from published series. The two groups showed no difference in attack rate or disease progression over 6 months. Influenza immunization in MS patients is neither associated with an increased exacerbation rate in the postvaccination period nor a change in disease course over the subsequent 6 months.

Blood flow capacity via direct acute myocardial revascularization

The concept of direct myocardial revascularization, achieving myocardial perfusion through means other than the normal coronary vasculature, has a long history with the most widely investigated technique being the Vineberg procedure; current interest centers around the encouraging preliminary clinical results obtained with transmyocardial laser revascularization. Despite significant previous research, the acute blood flow potential through the direct myocardial route remains unknown. Nontransmural laser channels were made in the distal LAD territory from the epicardial surface of 5 mongrel dogs to which an internal mammary artery was connected. A flow probe was placed on the distal most portion of the artery and an intercostal branch was cannulated for infusion of colored microspheres. Measurements were taken under baseline conditions and following LAD and epicardial collateral ligation. Under all conditions, blood flow pattern was of a to-and-fro nature. At baseline, there was an average 0.60 +/- 0.24 ml/min net flow into the myocardium which was all contained within 0.5 cm of the central channel with a final myocardial perfusion of 0.011 +/- 0.016 ml/min/g. Following induction of ischemia average flow increased to 1.41 +/- 0.51 ml/min which extended as far as 1 cm from the channel with a final myocardial perfusion of 0.22 +/- 0.19 ml/min/g. In conclusion, a limited amount of acute myocardial perfusion can be achieved by the present technique of direct myocardial revascularization and the amount of flow is highly dependent upon the amount of flow through the native circulation.

Sigma 2 receptors as potential biomarkers of proliferation in breast cancer

sigma 1 and sigma 2 receptors have been shown to exist in a number of rodent and human tumor cell lines. Although their expression is heterogeneous and their function is unknown, sigma receptors have been proposed as potential targets for diagnostic tumor-imaging agents. In this study, the density of sigma 2 receptors in proliferative (P) and quiescent (Q) cells of the mouse mammary adenocarcinoma, line 66, was examined. Scatchard analyses of sigma 2 receptors were performed on membrane preparations of 66 P cells from 3-day cultures and 66 Q cells from 7-, 10-, and 12-day cultures. The Scatchard studies revealed that 66 P cells had approximately 10 times more sigma 2 receptors/cell than the 66 Q cells from 10-day cultures. Although > 97% of the cells were quiescent after 7 days in culture, the maximum differential in the sigma 2 expression between 66 P and 66 Q cells was not attained until these cells had been in culture for 10 days. These data suggest that ligands labeled with positron-emitting or single photon-emitting radionuclides, which selectively bind sigma 2 receptors, have the potential to noninvasively assess the proliferative status of human breast tumors.

Is aprotinin indicated for reoperative valvular surgery?

BACKGROUND AND AIMS OF THE STUDY

While the hemostatic effect of aprotinin for patients undergoing reoperative coronary bypass is well established, it remains unclear whether these effects extend to patients undergoing reoperative valvular surgery.

METHODS

We examined our experience with 85 consecutive patients undergoing isolated reoperative valvular surgery with and without use of perioperative aprotinin in order to investigate differences in perioperative blood use, blood loss, bleeding complications, mortality and incidence of myocardial injury.

RESULTS

Aprotinin recipients benefited from a significant reduction in bleeding complications, and a decrease in perioperative and in-hospital mortalities as compared with untreated patients. Anaphylactic reactions and clinically significant thromboembolic events were not observed. There was no difference in the incidence of renal dysfunction or myocardial injury among aprotinin-treated and untreated groups.

CONCLUSIONS

Our results indicate that aprotinin therapy can be safely administered to patients undergoing reoperative valvular surgery. No increased incidence of anaphylactic reactions, renal dysfunction or perioperative myocardial injury was noted. The observed reductions in bleeding complications and perioperative and in-hospital mortality strongly warrant the evaluation of aprotinin for reoperative valvular surgery in a prospective fashion.

Comparison of two fluorine-18 labeled benzamide derivatives that bind reversibly to dopamine D2 receptors: in vitro binding studies and positron emission tomography

The purpose of the present set of studies was to characterize, in vitro and in vivo, two benzamide analogues, 2,3-dimethoxy-N-[1-(4-fluorobenzyl)piperidin4yl]benzamide (MBP) and 4'-fluoroclebopride (FCP), for studying dopamine D2 receptors with Positron Emission Tomography (PET). In vitro binding studies were conducted to determine the affinities of MBP and FCP to the three subtypes of dopamine D2 receptors: D2(long), D3, and D4 receptors. MBP was found to have a high affinity (Ki = 1-8 nM) for all three subtypes of the D2 receptor, whereas FCP had nanomolar affinity (Ki approximately 5.5 nM) for D2(long) and D3 receptors, and a lower affinity for D4 receptors (Ki = 144 nM). In vitro binding studies also revealed that MBP had a relatively high affinity for rho1 receptors (Ki = 11 nM) compared to FCP (Ki = 340 nM). PET imaging studies were conducted in rhesus monkeys with the fluorine-18 labeled analogues of each compound. Both [18F]MBP and [18F]FCP displayed reversible binding kinetics during the 3 h time course of PET. [18F]FCP was found to have a higher basal ganglia:cerebellum ratio and lower variability in the rate of washout from D2 receptors in vivo relative to [18F]MBP. Neither radiotracer was found to produce radiolabeled metabolites capable of crossing the blood-brain barrier. The high rho1 binding affinity and low basal ganglia:cerebellum ratio of [18F]MBP indicate that this ligand may not be suitable for quantitative studies of D2 receptors. The results from the in vitro and in vivo studies indicate that [18F]FCP is a promising ligand for studying D2 receptors with PET.

Variability of right ventricular functional recovery after lung transplantation

BACKGROUND

The purpose of this study was to assess by echocardiography the effects of lung transplantation on recovery of right ventricular (RV) function in patients with preoperative RV dysfunction.

METHODS

Fourteen (20%) of 71 lung transplant recipients were identified by echocardiography as manifesting abnormal RV function before lung transplantation. These 14 patients were selected for follow-up echocardiographic study 8 months after transplantation.

RESULTS

RV function improved significantly in the study group. Mean RV end-diastolic area decreased from 26.8 +/- 7.9 cm2 to 20.1 +/- 4.7 cm2 (P < 0.01); mean RV end-systolic area decreased from 21.5 +/- 6.8 cm2 to 13.1 +/- 4.2 (P < 0.01); and mean RV fractional area change (FAC) increased from 20.4 +/- 3.3% to 35.8 +/- 8.9% (P < 0.001). A subgroup of four patients, however, exhibited no change in RV function. Patients who achieved improvement in RV function tended to be younger, had shorter duration of disease before transplantation, and had higher pulmonary arterial (PA) pressures before transplantation (PA systolic, 89 +/- 28 mmHg vs. 38 +/- 11 mmHg, P < 0.001; PA diastolic, 42 +/- 11 mmHg vs. 19 +/- 3 mmHg, P < 0.002). Each of the eight patients with primary pulmonary hypertension exhibited improvement in RV function (mean delta FAC +20.6 +/- 5.9%), while two of three patients with emphysema and both patients with idiopathic pulmonary fibrosis failed to achieve improvement in RV function (mean delta FAC +2.3 +/- 1.2%).

CONCLUSIONS

Improvement of RV function assessed by echocardiography occurs after lung transplantation, even in patients with severe preoperative RV dysfunction. However, the degree of improvement is variable and may depend on the degree of RV after-load reduction and the presence or absence of intrinsic myocardial disease. RV ejection parameters do not distinguish between these two possibilities.

Consequences of electroencephalographic-suppressive doses of propofol in conjunction with deep hypothermic circulatory arrest

BACKGROUND

Some patients who undergo cerebral aneurysm surgery require cardiopulmonary bypass and deep hypothermic circulatory arrest. During bypass, these patients often are given large doses of a supplemental anesthetic agent in the hope that additional cerebral protection will be provided. Pharmacologic brain protection, however, has been associated with undesirable side effects. These side effects were evaluated in patients who received large doses of propofol.

METHODS

Thirteen neurosurgical patients underwent cardiopulmonary bypass and deep hypothermic circulatory arrest to facilitate clip application to a giant or otherwise high-risk cerebral aneurysm. Electroencephalographic burst suppression was established before bypass with an infusion of propofol, and the infusion was continued until the end of surgery. Hemodynamic and echocardiographic measurements were made before and during the prebypass propofol infusion and again after bypass. Emergence time also was determined.

RESULTS

Prebypass propofol at 243 +/- 57 micrograms.kg-1.min-1 decreased vascular resistance from 34 +/- 8 to 27 +/- 8 units without changing heart rate, arterial or filling pressures, cardiac index, stroke volume, or ejection fraction. Propofol blood concentration was 8 +/- 2 micrograms/ml. Myocardial wall motion appeared hyperdynamic at the end of cardiopulmonary bypass, and all patients were weaned therefrom without inotropic support. After bypass, vascular resistance decreased further, and cardiovascular performance was improved compared to baseline values. Nine of the 13 patients emerged from anesthesia and were able to follow commands at 3.1 +/- 1.4 h. Three others had strokes and a fourth had cerebral swelling.

CONCLUSIONS

Propofol infused at a rate sufficient to suppress the electroencephalogram does not depress the heart or excessively prolong emergence from anesthesia after cardiopulmonary bypass and deep hypothermic circulatory arrest.

Blunt cardiac injuries in children: a postmortem study

We reviewed the records of the Chief Coroner for all pediatric (< 16 years of age) trauma fatalities in Ontario (pediatric population of 2 million) for the period January 1, 1988 through December 31, 1990. Forty-one (14.5%) of 282 patients for which complete autopsy data were available had sustained cardiac injuries. Nineteen patients (46%) died at the scene of the accident, 15 patients (37%) died in an emergency department, and seven patients (17%) died during hospitalization. Rupture of a cardiac chamber occurred in 16 cases; it was the main cause of death in eight cases and a contributing factor in the remainder. Cardiac contusion without chamber rupture was present in 25 cases, but in none of the cases was it the cause of death. Brain injury was the cause of death in 16 (64%) of the cases of cardiac contusion. Cardiac injuries are more common among children who die from blunt trauma than previous reports have suggested. However, because these injuries are often rapidly fatal, many patients die before they reach a hospital. With improvements in emergency medical services and the resulting reduction in transit time, more patients may reach trauma centers alive. A high index of suspicion and rapid diagnosis and treatment of these injuries can save the lives of some of these patients.

Tissue iron storage patterns in fetal hydrops associated with congestive heart failure

To learn whether fetal congestive heart failure causes a characteristic tissue iron storage pattern, we selected 15 neonatal autopsy cases of hydrops fetalis in which both the clinical and gross autopsy findings suggested intrauterine congestive heart failure. The latter appeared to be due to functional causes in 10 (3 nonhemolytic anemia, 4 cardiac dysrhythmia, 3 dilated cardiomyopathy) and was associated with cardiac malformation in 5. We graded the amount of hepatocellular siderosis, reticuloendothelial siderosis, and renal tubular siderosis in Perls-stained microscopic sections of liver, spleen, and kidney and compared the iron storage pattern with that in 15 normally developed neonatal autopsy controls (4 preterm, 11 term) and a further 7 with hemolytic anemia (5 alpha-thalassemia, 2 parvovirus B19 infection). Liver cell siderosis was absent in the three cases with nonhemolytic anemia. It was increased in 11 of the remaining 12 cases, as in hemolytic anemia controls. Among the five cardiac malformation cases, three had proximal renal tubular siderosis (as in hemolytic anemia controls) attributed to turbulent blood flow through the heart. Among the five, hydrops appeared to be due to prenatal closure of the foramen ovale in one and to prenatal constriction of the ductus arteriosus in another. In one of the five, and despite complex malformation of the heart, hydrops appeared to be due to complete heart block. We concluded that, although clinical information and morphologic assessment of the heart were basic to identifying a cardiac cause of fetal hydrops, histologic assessment of the pattern of iron storage helped confirm the pathologic diagnosis. Analysis of the pathologic findings led to a scheme for categorizing cardiogenic fetal hydrops.

Histologic appearance of transmyocardial laser channels after 4 1/2 weeks

Preliminary results of clinical studies suggest that transmyocardial laser revascularization is an effective treatment for patients with chronic angina that cannot be treated by other means. The mechanism of this effect remains controversial. We present autopsy results from a patient obtained 4 1/2 weeks after operation that show that the channels do not maintain patency. Further work is needed to determine the frequency of channel patency and its relation to clinical benefit.

A pancreatic cyst of the anterior mediastinum

Although heterotopia of pancreatic tissue is a developmental anomaly found in approximately 2% of all autopsies, pancreatic tissue within the thorax and mediastinum is uncommon. In most of these instances, the pancreatic acini and islets are components of gastroenteric duplication cysts, intralobar pulmonary sequestrations, or teratomas. We describe the clinicopathologic features and hormonal profile of a patient with an anterior mediastinal cyst formed entirely by pancreatic tissue. To our knowledge, the English literature reveals only two previous examples of this lesion. The patient, a previously healthy 16-year-old girl, was found to have a cystic lesion in the anterior mediastinum during investigation of an asymptomatic heart murmur. The lesion measured 12 cm in maximal diameter and contained dark, turbid fluid. The wall was fibrotic and contained a haphazard mixture of ducts, exocrine acini, and islets. In many areas, the ducts and islets formed ductuloinsular complexes resembling those seen in diffuse nesidioblastosis. Immunohistochemical examination showed that the islets contained an increased number of B and PP cells, recapitulating the hormonal profile of the ventral anlage of the fetal pancreas. The similarity between this lesion and a fetal pancreas was further supported by the presence of a significant number of islet cells containing gastrin. The histogenesis of this lesion is unclear; we think that this lesion represents a derivative of the ventral (anterior) primitive foregut, but unidirectional differentiation of a benign cystic teratoma cannot be excluded.

Does blood flow through holmium:YAG transmyocardial laser channels?

BACKGROUND

Early reports indicate that transmyocardial laser revascularization improves symptoms in patients with refractory angina. However, there is little experimental evidence of whether blood flow through channels is the mechanism of action.

METHODS

Endocardial channels were made in the distribution of the left anterior descending coronary artery in canine hearts (n = 5) using a holmium:yttrium-aluminum garnet laser. Hearts were excised acutely while perfused in a retrograde fashion from a second dog so that the aortic valve always remained closed. The proximal left anterior descending coronary artery was ligated. To measure direct transmyocardial blood flow, colored microspheres were injected into the left ventricular chamber.

RESULTS

The number of spheres per gram of tissue in the channel region was significantly higher than in the control region (low load, 302.5 +/- 169.0 versus 41.8 +/- 59.4; high load, 208.4 +/- 138.3 versus 5.8 +/- 11.7; both, p < 0.05). However, the estimated regional blood flow through the channels was extremely low (<0.01 mL/g/min. In the chronic setting (n = 4) (2-week survival), no flow as detected through the channels, and the endocardial entry points were closed.

CONCLUSIONS

Transmyocardial blood flow does not appear to occur through channels made with the holmium:yttrium-aluminum garnet laser. It remains to be determined whether this is the case with other types of lasers.

Safety of repeat aprotinin administration for LVAD recipients undergoing cardiac transplantation

BACKGROUND

Anecdotal reports of allergic and anaphylactic reactions after aprotinin therapy have raised concern that its repeat use may be associated with substantial morbidity.

METHODS

To address this concern, we reviewed our experience with all patients who underwent implantation of a left ventricular assist device and subsequent cardiac transplantation with perioperative use of aprotinin.

RESULTS

Twenty-three patients received full-dose aprotinin during left ventricular assist device implantation and subsequent cardiac transplantation. All patients tolerated primary exposure to aprotinin without complication. One episode of anaphylaxis after secondary exposure was treated with rapid institution of cardiopulmonary bypass. Although renal dysfunction was observed shortly after cardiac transplantation in 30.4% of patients, the effect was transient and occurred in the presence of cyclosporine. The one perioperative death after secondary exposure was unrelated to bleeding complications. No clinically evident thromboembolic events were documented.

CONCLUSIONS

Primary and secondary exposure to aprotinin during operation with cardiopulmonary bypass is associated with limited intraoperative blood use, a low incidence of transient renal dysfunction and anaphylaxis, a rare need of reoperation for bleeding, and no clinical thromboembolic events.

Immunologic monitoring in lung allograft recipients

To identify patients with increased risk of chronic lung allograft rejection, we assessed the utility of an in vitro biopsy-derived lymphocyte growth assay and serum anti-HLA antibody screening as a complement to currently available methods of monitoring lung allograft recipients. Lymphocyte growth assay was performed on bronchoscopic fragments of tissue cultured in medium with rIL-2. Seventy-nine biopsies from 31 lung transplant recipients were tested by lymphocyte growth assay, and results were correlated with histopathology findings. Positive lymphocyte growth was found in 12/26 (46%) episodes of acute rejection, 5/44 biopsies without rejection (11%), and 0/9 episodes of bronchitis. Positive lymphocyte growth was seen in 7/16 (44%) grade A1 rejections and in 5/10 (50%) grade A2 rejections, as opposed to only 5/44 (11%) grade A0 (no rejection) biopsies (P < 0.01 for both A1 and A2 with respect to A0). Actuarial probability of remaining free from obliterative bronchiolitis (OB)* tended to be higher in patients who did not exhibit lymphocyte growth in biopsies. Sequential samples of sera obtained at the time of the biopsy were screened for lymphocytotoxic anti-HLA antibodies. Twenty-two of 44 recipients (50%) developed anti-HLA antibodies during the first postoperative year, exhibiting greater than 10% reactivity to an HLA reference panel of lymphocytes in four or more consecutive serum samples. Actuarial survival of lung allograft recipients with anti-HLA antibodies (n = 22) was lower than in those without anti-HLA antibodies (n = 22; P = 0.03). Of the 22 antibody producers, 7/12 died as a consequence of OB. Of the 22 non-antibody-producers, 1/2 deaths occurred as a consequence of OB. Anti-HLA antibodies were present in 9/11 instances of OB (82% sensitivity) and in 13/33 patients without OB (61% specificity; P = 0.03). These data indicate that lung transplant recipients with positive lymphocyte growth and anti-HLA antibodies are at an increased risk of chronic allograft rejection.

Two decades of cardiac transplantation at the Columbia-Presbyterian Medical Center: 1977-1997

Since its inception in 1977, the Cardiac Transplantation Service at Columbia-Presbyterian Medical Center has performed more than 900 heart transplant procedures, with a one-year survival rate of approximately 80%, and a 5-year survival rate of approximately 60%. Throughout our 20-year experience, the criteria for eligibility both donors and recipients has widened to include older and "reanimated" donors for selected recipients, as well as an extensive experience with recipients bridged to transplantation with mechanical assist devices. Of particular interest in recent years has been the need for additional therapy for the highly sensitized transplant candidate and ultimate transplant recipient, whose immunosuppressive regimen must be continuously monitored and modified to ensure graft survival. In light of the persistent donor organ crisis, continued efforts are being developed to more accurately characterize the transplant candidate waiting list in order to identify those patients who may be better served by either medical management or an alternative surgical procedure to transplantation, including high-risk coronary revascularization and mechanical or biological assistance. Current research interests at CPMC include left ventricular assist devices, xenotransplantation, and management of both transplant coronary artery disease and immunologic sensitization. Ongoing investigations in these and other areas of transplantation have been established to encourage continued growth both within the field and at CPMC through the 21st century.

Development of the respiratory diaphragm in childhood: diaphragmatic contraction band necrosis in sudden death

The authors studied the respiratory diaphragm in 50 normally grown infants and children aged 1 to 16 years at the time of sudden death. By comparing the weights of both costal diaphragm and heart with age and height, the authors found that the diaphragm grows proportionately to the body as a whole and to the heart in particular. Diaphragmatic contraction band necrosis was found in 15 cases (30%). The incidence was similar in subjects dying of asphyxia (five of 21) to that in those dying of trauma (five of 20). It was present in two of 15 of those that died at once, and 13 of 35 of those who survived for varying periods with or without cardiopulmonary resuscitation. Myocardial contraction band necrosis was more common than diaphragmatic contraction band necrosis, being present in five of 11 of those who died at once, and 16 of 26 of those that survived for a period. Among individual subjects, the authors found no correlation of the presence of the diaphragmatic lesion with either cause or mode of death. Based on a comparison with the morphologically similar myocardial lesion, the etiopathogenesis of diaphragmatic contraction band necrosis may concern a local catecholamine effect.

Microsurgery in a rat lung transplant model: analysis of benefit

With the use of microsurgery, we have developed a method of measuring hemodynamic parameters in a rat not possible with previous technology. Three groups of rats were studied: a chemically induced pulmonary hypertensive group (PH); a chemically induced pulmonary hypertensive group treated with single lung transplantation (LT); and an untreated, control group (C). Cardiac output, heart rate, and pulmonary vascular resistance were then calculated in each group from data obtained by 1 mm high fidelity micromanometers and an ultrasonic flow probe. The results show that the data collected from the rodent model are reproducible within each group, and data quality is comparable to large animal models. With this new method, data can be collected in a small animal model at a fraction of the time and cost of large animal studies. Additionally, the complications of graft rejection in large animal studies are eliminated in an isogenic rodent model.

Cerebral dysfunction after cardiac operations in elderly patients

BACKGROUND

Cerebral injury remains a significant complication of cardiac operations. We determined the incidence of cerebral dysfunction in a population of elderly patients undergoing open chamber cardiac operations (group 1) as compared with a younger population (group 2) and an age-matched group of elderly patients undergoing major noncardiac operations (group 3).

METHODS

Sixty-eight patients (55 for open chamber cardiac operations and 13 for noncardiac operations) were prospectively studied. Patients were evaluated preoperatively and postoperatively before hospital discharge using a complete neurologic examination and a battery of standard neuropsychometric tests, and at surgical follow-up with neuropsychometric tests only.

RESULTS

Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in all groups. No statistically significant differences in incidence were found. The neuropsychometric performance of group 1 patients was statistically different from that of patients in groups 2 and 3 only in the early follow-up period.

CONCLUSIONS

Elderly patients having open chamber cardiac operations exhibit significantly more cerebral dysfunction in the early postoperative period than those undergoing major noncardiac operations and younger patients after open chamber procedures. These changes do not persist into the late follow-up period.

Safety and efficacy of aprotinin under conditions of deep hypothermia and circulatory arrest

Aprotinin has been successfully used to reduce blood loss and blood product requirements in patients undergoing primary and reoperative cardiac operations. Its safety and efficacy during profound hypothermia and circulatory arrest have been questioned, however. A retrospective review compared 24 patients who received aprotinin during complex aortic procedures under profound hypothermia and circulatory arrest with 24 age-matched patients undergoing similar procedures without aprotinin. Activated clotting time was maintained at longer than 500 seconds (kaolin activating agent) or longer than 750 seconds (celite). We observed no statistically significant difference in the incidence of neurologic events (p not significant) or myocardial infarctions (p not significant), and there was a trend toward reduced in-hospital mortality rate in aprotinin-treated patients. A higher incidence of postoperative renal dysfunction was encountered in aprotinin-treated patients. Aprotinin recipients had a significant reduction in requirements for postoperative homologous erythrocytes (p = 0.01). We conclude that aprotinin may be safely and effectively used in patients undergoing deep hypothermia and circulatory arrest.

Development of a clinically applicable high-speed flow cytometer for the isolation of transplantable human hematopoietic stem cells

A high-speed cell sorter capable of a throughput speed 4-5-fold greater than commercially available systems was developed and evaluated as a processing tool for isolating purified hematopoietic stem cell grafts. The clinical high-speed sorter (CHSS) serves as a single-pass, multiparameter processing tool that provides the means to isolate a highly purified population of cells from starting cell populations with extremely low frequencies. The sorter incorporates environmental barriers to create a sterile environment for cell processing. Monoclonal antibodies and reagents produced under good manufacturing practices (GMP) are used to isolate hematopoietic stem cells by means of the CHSS. Using this technology, the CD34+Thy-1+Lin- hematopoietic stem cell population has been isolated from normal adult bone marrow and mobilized peripheral blood. The sorted cells have been shown to be sterile and viable and to retain hematopoietic function.

Ischemia-induced interleukin-8 release after human heart transplantation. A potential role for endothelial cells

BACKGROUND

Interleukin-8 (IL-8) secreted from endothelial cells is a powerful neutrophil chemoattractant and activator. We hypothesized that human endothelial cells deprived of oxygen would secrete IL-8, which might translate into elevated IL-8 production after cardiac ischemia. Furthermore, we hypothesized that coronary sinus (CS) IL-8 levels would be particularly high after cardiac preservation for transplantation, due to extended ischemic times.

METHODS AND RESULTS

Human saphenous vein endothelial cells exposed to a hypoxic environment (PO2 < 20 mm Hg) demonstrated a time-dependent release of IL-8 (measured by ELISA) into the culture supernatant as early as 4 hours after exposure. To determine whether cardiac preservation in humans was associated with IL-8 production, we obtained CS blood samples 5 minutes after reperfusion in a consecutive series of patients after they underwent cardiac transplantation (CTX, n = 20) or elective cardiac surgery (non-CTX, n = 21). CTX patients demonstrated significantly higher CS IL-8 levels than non-CTX patients (325 +/- 123 versus 50 +/- 17 ng/mL, respectively, P < .05). Further analysis of the CS samples revealed that a biochemical marker of myocyte injury (myoglobin) was similarly elevated in the CTX patients compared with the non-CTX patients (3340 +/- 625 versus 1151 +/- 525 ng/mL, respectively, P < .05).

CONCLUSIONS

These differences may reflect the longer ischemic times of CTX compared with non-CTX hearts (161 +/- 10 versus 80 +/- 6 minutes, P < .0001) and suggest that the neutrophil chemoattractant/activator IL-8 may contribute to myocyte injury after prolonged hypothermic cardiac ischemia, as occurs during human cardiac transplantation.

Inhaled nitric oxide fails to confer the pulmonary protection provided by distal stimulation of the nitric oxide pathway at the level of cyclic guanosine monophosphate

It has been suggested that inhaled nitric oxide gas may be beneficial after lung transplantation, because endogenous levels of pulmonary nitric oxide decline rapidly after reperfusion. However theoretical concerns remain about the formation of highly toxic oxidants during the quenching of nitric oxide by superoxide. To determine whether distal stimulation of the nitric oxide-cyclic guanosine monophosphate pathway at the level of cyclic guanosine monophosphate might confer the beneficial vascular effects of nitric oxide without its potential toxicities, we studied an orthotopic rat left lung transplant model. In this model, hemodynamic and survival measurements can be obtained independent of the native right lung. Lungs were preserved for 6 hours at 4 degrees C in Euro-Collins solution alone (control, n = 6) or supplemented with the cyclic guanosine monophosphate analog, 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic guanosine monophosphate (cGMP, n = 4). In additional experiments in which lungs were preserved with Euro-Collins solution alone, inhaled nitric oxide was administered during reperfusion (NO, n = 12). Thirty minutes after transplantation and ligation of the native right pulmonary artery, pulmonary vascular resistance, arterial oxygenation, graft neutrophil infiltration (myeloperoxidase activity), and recipient survival were evaluated. Cyclic guanosine monophosphate decreased pulmonary vascular resistance (1.1 +/- 0.2 vs 12.1 +/- 6.3 mm Hg/ml/min, p < 0.05), improved oxygen tension (369 +/- 56 vs 82.8 +/- 48 mm Hg, p < 0.05), reduced myeloperoxidase activity (1.7 +/- 0.3 vs 3.1 +/- 0.9 delta Abs 460 nm/min, p < 0.05), and improved recipient survival (100% vs 0%, p < 0.005) compared with Euro-Collins solution alone (control group). Animals receiving inhaled nitric oxide during reperfusion did not differ from control animals with respect to any of these parameters. These data suggest that distal stimulation of the nitric oxide-cyclic guanosine monophosphate pathway at the level of cyclic guanosine monophosphate has a protective effect that is not seen with inhaled nitric oxide in the immediate pulmonary reperfusion period.

Blockade of the human platelet GPIIb/IIIa receptor by a murine monoclonal antibody Fab fragment (7E3): potent dose-dependent inhibition of platelet function

The platelet glycoprotein (GP) IIb/IIIa receptor can bind fibrinogen, von Willebrand factor, and other adhesive ligands; this binding is the final common pathway mediating platelet aggregation. The purpose of this study was to evaluate the safety and platelet inhibitory characteristics of the Fab fragment of the murine monoclonal anti-GPII/IIIa 7E3 antibody (m7E3 Fab) when administered intravenously as a single bolus dose, as a single and repeat bolus dose, and as a single bolus dose followed by continuous infusions of varying duration. Various dosage regimens of m7E3 Fab were studied in 74 patients with stable angina. Dosage regimens included single doses of m7E3 Fab from 0.1 to 0.3 mg/kg, a single dose of 0.20-0.30 mg/kg, and a repeat dose of 0.05 mg/kg, or a loading dose followed by a continuous infusion of m7E3 Fab for up to 36 hours. To assess the effect of m7E3 Fab on platelet function, quantitative blockade of GPIIb/IIIa receptors, inhibition of ex vivo platelet aggregation, and template bleeding time were measured in all patients. Dose-dependent inhibition of platelet function was evident in response to escalating bolus doses of m7E3 Fab, with maximum inhibition observed at 0.25-0.30 mg/kg body weight; at the 0.30 mg/kg dose, mean (+/- SE) GPIIb/IIIa receptor blockade was 81 +/- 3%, ex vivo platelet aggregation in response to 20 microM ADP was 14 +/- 6% of baseline, and the median bleeding time was > 20 minutes. Although platelet function gradually recovered following a single bolus injection, platelet inhibition could be sustained by continuous, low-dose infusion of the antibody. Platelet inhibition occurred within minutes, but m7E3 Fab that did not bind to platelets cleared rapidly from circulation. Sixteen percent of the m7E3 Fab-injected subjects exhibited low titer, human anti-murine antibody responses. No significant bleeding or allergic reactions were observed in any patients. One of the 74 patients developed transient thrombocytopenia soon after receiving m7E3 Fab. These studies establish that m7E3 Fab can be administered safely at doses that cause profound inhibition of platelet function.

Single-stage treatment of sternal wound complications in heart transplant recipients in whom pectoralis major myocutaneous advancement flaps were used

Treatment of sternal wound complications is controversial, particularly in immunosuppressed heart transplant recipients. Regardless of the severity of infection, we combine immediate, aggressive débridement with bilateral pectoralis major myocutaneous advancement flaps in a single procedure. Compared with management with pectoralis major turnover flaps or distant pedicled muscle flaps, treatment of these sternal wounds with pectoralis major myocutaneous advancement flaps is simpler and quicker and provides better aesthetic results. Furthermore, because pectoralis major myocutaneous flaps are based on the thoracoacromial arteries, whether or not the internal mammary arteries have previously been harvested for coronary grafts is irrelevant. Twenty consecutive heart transplant recipients with sternal wound complications were treated with this technique. No intraoperative or perioperative deaths occurred. The morbidity rate was 30%, with seroma treated by needle aspiration in four patients (20%) being the most common complication. Only one patient had a postoperative wound infection. All patients had excellent functional and aesthetic results.

Heart transplantation in children with congenital heart disease

OBJECTIVES

The aim of this study was to describe heart transplantation in children with congenital heart disease and to compare the results with those in children undergoing transplantation for other cardiac diseases.

BACKGROUND

Reports describe decreased survival after heart transplantation in children with congenital heart disease compared with those with cardiomyopathy. However, transplantation is increasingly being considered in the surgical management of children with complex congenital heart disease. Present-day results from this group require reassessment.

METHODS

The diagnoses, previous operations and indications for transplantation were characterized in children with congenital heart disease. Pretransplant course, graft ischemia time, post-transplant survival and outcome (rejection frequency, infection rate, length of hospital stay) were compared with those in children undergoing transplantation for other reasons (n = 47).

RESULTS

Thirty-seven children (mean [+/- SD] age 9 +/- 6 years) with congenital heart disease underwent transplantation; 86% had undergone one or more previous operations. Repair of extracardiac defects at transplantation was necessary in 23 patients. Causes of death after transplantation were donor failure in two patients, surgical bleeding in two, pulmonary hemorrhage in one, infection in four, rejection in three and graft atherosclerosis in one. No difference in 1- and 5-year survival rates (70% vs. 77% and 64% vs. 65%, respectively), rejection frequency or length of hospital stay was seen between children with and without congenital heart disease. Cardiopulmonary bypass and donor ischemia time were significantly longer in patients with congenital heart disease. Serious infections were more common in children with than without congenital heart disease (13 of 37 vs. 6 of 47, respectively, p = 0.01).

CONCLUSIONS

Despite the more complex cardiac surgery required at implantation and longer donor ischemic time, heart transplantation can be performed in children with complex congenital heart disease with success similar to that in patients with other cardiac diseases.

Metabolic and hemodynamic responses to walking with shoulder-worn exercise weights: a brief report

This study examined the acute physiological responses to steady-rate walking with additional weight carried at shoulder level. Sixteen healthy subjects completed two treadmill walking bouts with and without a 4.54-kg shoulder-worn load carriage system in place. Addition of the external shoulder weights resulted in small increases in level walking oxygen uptake (+0.44 ml.kg-1.min-1; +0.03 L.min-1) and minute ventilation volumes (+0.81 L.min-1) (p < 0.05). RER values, heart rate (+3 beats.min-1), and blood pressure responses [systolic blood pressure (SBP) + 4.5 mm Hg, diastolic blood pressure (DBP) + 1.3 mm Hg] were not significantly changed (p > 0.05). These findings indicate that the efficacy of shoulder-worn exercise weights to augment the physiological demand of walking exercise is marginal at best.

Ibogaine possesses a selective affinity for sigma 2 receptors

The alkaloid ibogaine is potentially useful to reduce craving for several drugs of abuse, but its mechanism of action is not known. In the current study, in vitro studies were conducted in order to determine the affinity of ibogaine for sigma receptors. Our results indicate that ibogaine has a relatively high affinity for sigma 2 receptors (Ki = 90.4 and 250 nM) and a significantly lower affinity for sigma 1 receptors (Ki = 9310 nM). These data suggest that ibogaine may have a higher affinity at sigma 2 receptors than any other known CNS receptor. Its low affinity for sigma 1 receptors also suggests that ibogaine may be a suitable lead compound for structure-activity relationship studies aimed at developing sigma 2-selective ligands.

Rapid optimization of electroporation conditions for plant cells, protoplasts, and pollen

The optimization of electroporation conditions for maximal uptake of DNA during direct gene transfer experiments is critical to achieve high levels of gene expression in transformed plant cells. Two stains, trypan blue and fluorescein diacetate, have been applied to optimize electroporation conditions for three plant cell types, using different square wave and exponential wave electroporation devices. The different cell types included protoplasts from tobacco, a stable mixotrophic suspension cell culture from soybean with intact cell walls, and germinating pollen from alfalfa and tobacco. Successful electroporation of each of these cell types was obtained, even in the presence of an intact cell wall when conditions were optimized for the electroporation pulse. The optimal field strength for each of these cells differs, protoplasts having the lowest optimal pulse field strength, followed by suspension cells and finally germinating pollen requiring the strongest electroporation pulse. A rapid procedure is described for optimizing electroporation parameters using different types of cells from different plant sources.

Use of aprotinin in LVAD recipients reduces blood loss, blood use, and perioperative mortality

Aprotinin, a bovine protease inhibitor, has been used extensively in patients undergoing cardiac surgical procedures in an effort to minimize blood loss and prevent the complications associated with blood replacement. We sought to evaluate the effect of aprotinin on postoperative blood loss, renal function, and the incidence of right ventricular failure in patients undergoing placement of a TCI Heartmate left ventricular assist device as a bridge to cardiac transplantation. Retrospective data analysis in 142 patients (42 receiving aprotinin and 100 untreated) demonstrated that the use of aprotinin was associated with a significant decrease in postoperative blood loss (p = 0.019) and in the intraoperative packed red blood cell transfusion (p = 0.019) and total blood product (p = 0.016) requirements. A transient, yet significant, increase in the postoperative creatinine level in the aprotinin group (p = 0.0006), but not in blood urea nitrogen level (p = 0.22), was noted. Interestingly, we noted an association between blood loss and the subsequent development of right ventricular failure; patients who required a right ventricular assist device bled significantly more than did those who did not suffer right ventricular failure (p = 0.02). Additionally, aprotinin recipients benefited by a reduction of nearly one half in the incidence of the need for a right ventricular assist device. The incidence of perioperative mortality was reduced in those receiving aprotinin compared with that in untreated patients, (p = 0.05). We conclude that aprotinin is safe and effective in decreasing postoperative blood loss and intraoperative blood product requirements, and in reducing perioperative mortality in patients undergoing left ventricular assist device placement as a bridge to cardiac transplantation.

Vesamicol analogues as sigma ligands. Molecular determinants of selectivity at the vesamicol receptor

The present study compares the affinities of 2-(4-phenylpiperidino)cyclohexanol (vesamicol, 1) and selected analogues of the latter at the vesamicol receptor (VR) with the corresponding affinities at sigma 1 and sigma 2 binding sites. For this study, the parent structure 1 was divided into three fragments: A (cyclohexyl), B (piperidyl) and C (phenyl). Vesamicol analogues were then selected to reflect structural modifications in these fragments. Consistent with earlier reports, vesamicol was found to exhibit nanomolar affinities at the VR and sigma 1 and sigma 2 sites, resulting in poor selectivity for the VR over the sigma sites. Vesamicol analogues characterized by an acyclic A-fragment showed moderate to low affinities at the VR and moderate to high affinities at sigma 1 and sigma 2 sites. As a result, many of these analogues showed poor selectivity for the VR. Replacement of the C4 carbon of 1 with a halobenzyl amine resulted in higher affinities at the VR coupled with moderate to low affinities at sigma 1 and sigma 2 sites. The introduction of a benzofused substituent at the C4 and C5 positions of 1 (compound 2) resulted in a 200-fold increase in affinity at the VR accompanied by a 5- to 6-fold decrease in affinity at sigma 1 and sigma 2 sites relative to the parent structure. Consequently, compound 2 showed 12,000-fold higher affinity at the VR than at sigma sites. Restricting the rotation of fragment C relative to B (by means of alkyl and alkenyl bridges) generally yielded analogues with subnanomolar affinities at the VR. The corresponding affinities of these spirofused conformationally restricted analogues were moderate to poor at sigma 1 and sigma 2 sites when fragment A was preserved. In contrast, the affinities at sigma 1 and sigma 2 sites were decreased 3- to 11-fold when fragment A was modified at position C4 and decreased up to 100-fold with benzofusion at the C4 and C5 positions of fragment A. Consequently, the spirofused analogues 15-19 were among the most selective VR ligands examined. Thus, the effect of conformational restriction in fragments A and B-C is to increase affinity at the VR while decreasing affinity at sigma 1 and sigma 2 sites, and thereby increasing selectivity for the VR over the sigma sites.

Management strategies for pulmonary vein thrombosis following single lung transplantation

Pulmonary vein thrombosis following lung transplantation is an infrequently reported and often fatal vascular complication. Two cases of early pulmonary vein thrombosis following single lung transplantation are described. Both patients underwent surgical thrombectomy and anastomotic reconstruction following institution of cardiopulmonary bypass, but died of multiorgan failure within 5 days of diagnosis. The efficacy of transesophageal echocardiography as a diagnostic modality, as well as medical and surgical management strategies for thrombectomy, are discussed.

Do standard monitoring sites reflect true brain temperature when profound hypothermia is rapidly induced and reversed?

BACKGROUND

Brain temperature is closely approximated by most body temperature measurements under normal anesthetic conditions. However, when thermal autoregulation is overridden, large temperature gradients may prevail. This study sought to determine which of the standard temperature monitoring sites best approximates brain temperature when deep hypothermia is rapidly induced and reversed during cardiopulmonary bypass.

METHODS

Twenty-seven patients underwent cardiopulmonary bypass and deep hypothermic circulatory arrest in order for each to have a giant cerebral aneurysm surgically clipped. Brain temperatures were measured directly with a thermocouple embedded in the cerebral cortex. Eight other body temperatures were monitored simultaneously with less invasive sensors at standard sites.

RESULTS

Brain temperature decreased from 32.6 +/- 1.4 degrees C (mean +/- SD) to 16.7 +/- 1.7 degrees C in 28 +/- 7 min, for an average cerebral cooling rate of 0.59 +/- 0.15 degrees C/min. Circulatory arrest lasted 24 +/- 15 min and was followed by 63 +/- 17 min of rewarming at 0.31 +/- 0.09 degrees C/min. None of the monitored sites tracked cerebral temperature well throughout the entire hypothermic period. During rapid temperature change, nasopharyngeal, esophageal, and pulmonary artery temperatures corresponded to brain temperature with smaller mean differences than did those of the tympanic membrane, bladder, rectum, axilla, and sole of the foot. At circulatory arrest, nasopharyngeal, esophageal, and pulmonary artery mean temperatures were within 1 degree C of brain temperature, even though individual patients frequently exhibited disparate values at those sites.

CONCLUSIONS

When profound hypothermia is rapidly induced and reversed, temperature measurements made at standard monitoring sites may not reflect cerebral temperature. Measurements from the nasopharynx, esophagus, and pulmonary artery tend to match brain temperature best but only with an array of data can one feel comfortable disregarding discordant readings.

Nitroglycerin maintains graft vascular homeostasis and enhances preservation in an orthotopic rat lung transplant model

Transplanted lungs often fail during the peritransplantation period for poorly understood reasons. Because the nitric oxide pathway regulates pulmonary vascular tone, helps to maintain the integrity of the endothelial barrier, and modulates neutrophil adhesivity and activation, we hypothesized that perturbation of this pathway during the preservation and reperfusion of transplanted lungs might play a critical role in mediating early graft failure. To evaluate whether supplementing the preservation solution with the nitric oxide donor nitroglycerin enhances lung preservation for transplantation, we obtained hemodynamic measurements in a model of orthotopic left lung transplantation in the rat after ligation of the native right pulmonary artery. In these experiments, recipient survival and hemodynamics depended solely on the transplanted lung. The left lung was harvested from 22 rats, flushed with either lactated Ringer's solution alone (control, n = 11) or Ringer's solution supplemented with nitroglycerin (0.1 mg/ml, n = 11), preserved for 4 hours at 4 degrees C, and then transplanted using a rapid cuff technique for bronchial and vascular anastomoses. Nitroglycerin significantly improved arterial blood oxygenation (339 +/- 66 versus 130 +/- 12 mm Hg, p < 0.05), increased pulmonary arterial flow (7.6 +/- 1.9 versus 0.9 +/- 0.2 ml/min, p < 0.005), decreased pulmonary vascular resistance (1.7 +/- 0.4 versus 6.6 +/- 1.9 x 10(3) Wood units, p < 0.05), and enhanced recipient survival (64% versus 0%, p < 0.05). Control grafts had significantly greater neutrophil accumulation (50% greater as quantified by myeloperoxidase activity, p < 0.05) than grafts preserved in the presence of nitroglycerin. These studies show that supplementation of the preservation solution with the nitric oxide donor nitroglycerin maintains graft vascular homeostasis and significantly improves pulmonary function and recipient survival after transplantation.

Classmode: a new data format for real-time multiparameter data analysis and data compression

A new data acquisition and analysis format (classmode) was developed that allows real-time data classification in a flow cytometer. In our cytometer, detected events were classified in real time by their presence or absence in a set of look-up tables (LUT). A modification of the cytometer hardware allows the exclusive transfer of the LUT data to the acquisition/storage computer. Using a combination of 8 LUTs, the analyzed events can be classified into 256 subpopulations. Real-time data classification results in an increased data transfer rate and a significant compression of the data.