Clinical efficacy of two dentin desensitizing agents

PURPOSE

To compare the clinical effect over 3 months of two commercially available desensitizing agents on the level of discomfort of patients with complaints of dentin sensitivity.

MATERIALS AND METHODS

An oxalate-containing pre-polymerized resin suspension (Pain-Free), a 0.7% fluoride solution (DentinBloc), and a distilled water placebo were compared in a clinical setting. Ten volunteer patients exhibiting three or more teeth that were sensitive to touch and to a stream of forced air were enrolled in the study (52 teeth total). Each patient's level of sensitivity to tactile stimuli and to a forced air stream was recorded using a visual analog scale (VAS). The tactile stimulus was a metal probe rubbed across the exposed dentin with a constant pressure of 40 grams. A 1-second blast of air from a dental unit air syringe was used to generate the air stream. The desensitizing agents were applied according to manufacturers' guidelines. Sensitivity measurements were recorded at baseline, immediately after treatment, at 1 week, 1 month, and at 3 months. VAS pain scores were analyzed using a repeated measures ANOVA (alpha = 0.05).

RESULTS

The pre-polymerized resin suspension (Pain-Free), the fluoride-containing solution (DentinBloc), and the placebo all decreased dentin sensitivity. No significant difference was found among the desensitizing agents at any time period (P > 0.05).

Human complement regulatory proteins protect swine lungs from xenogeneic injury

BACKGROUND

Pulmonary xenotransplantation is not possible because of hyperacute lung injury, the pathogenesis of which is unknown. This study evaluates complement-dependent pathways of pulmonary injury during heterologous perfusion of swine lungs.

METHODS

Lungs from unmodified swine and swine expressing human decay-accelerating factor and human CD59 (hDAF/hCD59 swine) were perfused with either human plasma or baboon blood. Pulmonary vascular resistance and static pulmonary compliance were measured serially, and swine lung tissue were examined by light microscopy. Complement activation was assessed by serial measurements of baboon plasma C3a-desArg concentrations.

RESULTS

Perfusion of unmodified swine lungs with human plasma and baboon blood resulted in hyperacute lung injury within minutes of perfusion. However, function was preserved in swine lungs expressing human decay-accelerating factor and human CD59. In both study groups, xenogeneic perfusion with baboon blood resulted in at least a sevenfold increase in plasma C3a-desArg levels suggesting transient activation of complement.

CONCLUSIONS

Lungs from swine expressing human decay-accelerating factor and human CD59 were resistant to injury during perfusion with human plasma and baboon blood, indicating that complement mediated some of the features of xenogeneic acute lung injury.

Fracture strength of Class 2 amalgams with various cavity-lining materials

This in vitro study compared the fracture resistance of class 2 amalgam restorations placed over seven materials: three resin-modified glass-ionomer cements (Fuji II LC, Vitrebond, and Vitremer), one polyacid-modified composite resin (VariGlass VLC), two conventional glass-ionomer cements (Ketac-Bond and GlasIonomer Cement), and one calcium-hydroxide material (Dycal). Eighty maxillary molars with flattened occlusal surfaces were divided into 14 experimental groups and two control (no liner) groups. One standardized class 2 amalgam cavity preparation was completed per tooth. Lining materials standardized at a thickness of 0.5 mm were placed in the approximal box portion of 10 test specimens per experimental group. Spherical amalgam was hand condensed into each cavity preparation. At 1 hour and again at 7 days, five samples from each group were fractured in compression using an Instron Universal Testing Machine. The force was directed at 10 degrees to the long axis of the tooth, 2.0 mm inside the approximal portion of the restoration. Results were analyzed using a two-way ANOVA for time and material. No statistically significant differences were found among the materials and controls at either time interval tested (P > 0.05). A statistically significant difference was found (P < 0.05) when comparing 1-hour and 7-day strengths. The 7-day specimens were more resistant to fracture than the 1-hour specimens.

CONCLUSION

The fracture resistance of amalgam restorations was not affected by the presence of a material 0.5 mm thick placed in the approximal box when 3 mm of bulk of amalgam remained over it.

A comparison of two serological methods for detecting the immune response after rabies vaccination in dogs and cats being exported to rabies-free areas

Levels of rabies virus neutralizing antibody in sera from dogs and cats were titrated to endpoint by the Rapid Fluorescent Focus Inhibition Test (RFFIT) and retested by the RFFIT and the Fluorescent Antibody Virus Neutralization test (FAVN). The two tests were compared for their ability to detect the 0.5 international units/ml (I.U.) of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. No difference was observed in sensitivity or specificity for either method in tests of 168 sera from unvaccinated animals or 70 sera from vaccinated animals with high levels of neutralizing antibody (an initial RFFIT titre of > or = 1.0 I.U.). Test to test variation occurred for results obtained by both RFFIT and FAVN for 95 sera from vaccinated animals with low to moderate levels of neutralizing antibody (RFFIT titre < 1.0 I.U.). No significant differences were detected for the 95 sera in the frequency for one methodology more often than the other to have a positive response (> or = 0.5 I.U.), nor were significant differences detected for the symmetry (P = 0.43) or the marginal homogeneity (P = 0.39) of results obtained by the two methods. Both methods can adequately identity unvaccinated animals, but false positive and false negative results are possible for either method when a single test is used to measure the antibody response of low-responding vaccinated animals. Nucleotide sequence analysis identified several amino acid differences in stocks of the challenge rabies virus from different laboratories. The small differences in neutralizing antibody titre that may result from mutations in the challenge virus are not important for evaluating immunity induced by vaccines which are themselves prepared from a variety of different rabies virus strains, but differences in the challenge virus, rather than differences in methodology, may account for at least some of the discrepant results reported in inter-laboratory surveys. Comparative studies of serological methods for measuring rabies antibodies should use well-characterized unpassaged virus stocks obtained from a single reference laboratory.

Genetic Variation Among Vegetative Compatibility Groups of Fusarium oxysporum f. sp. cubense Analyzed by DNA Fingerprinting

ABSTRACT Genetic variation within a worldwide collection of 208 isolates of Fu-sarium oxysporum f. sp. cubense, representing physiological races 1, 2, 3, and 4 and the 20 reported vegetative compatibility groups (VCGs), was analyzed using modified DNA amplification fingerprinting. Also characterized were 133 isolates that did not belong to any of the reported VCGs of F. oxysporum f. sp. cubense including race 3 isolates from a Heliconia species and isolates from a symptomatic wild banana species growing in the jungle in peninsular Malaysia. The DNA fingerprint patterns were generally VCG specific, irrespective of geographic or host origin. A total of 33 different genotypes were identified within F. oxysporum f. sp. cu-bense; 19 genotypes were distinguished among the isolates that belonged to the 20 reported VCGs, and 14 new genotypes were identified among the isolates that did not belong to any of the existing VCGs. DNA fingerprinting analysis also allowed differentiation of nine clonal lineages within F. oxysporum f. sp. cubense. Five of these lineages each contained numerous closely related VCGs and genotypes, and the remaining four lineages each contained a single genotype. The genetic diversity and geographic distribution of several of these lineages of F. oxysporum f. sp. cubense suggests that they have coevolved with edible bananas and their wild diploid progenitors in Asia. DNA fingerprinting analysis of isolates from the wild pathosystem provides further evidence for the coevolution hypothesis. The genetic isolation and limited geographic distribution of four of the lineages of F. oxysporum f. sp. cubense suggests that the pathogen has also arisen independently, both within and outside of the center of origin of the host.

Myocardial recovery after ischemia and reperfusion injury is significantly impaired in hearts with transgenic overexpression of beta-adrenergic receptor kinase

BACKGROUND

beta-Adrenergic receptor kinase 1 (beta ARK1) mediates beta-adrenergic receptor signaling via receptor phosphorylation, which results in functional uncoupling. The physiological importance of beta ARK1 on cardiac performance in the setting of ischemia and reperfusion injury, however, has not been clearly established. In this study, the effects of beta ARK1 overexpression on myocardial recovery after ischemia and reperfusion injury were evaluated in transgenic mice with the use of an isolated work-performing murine heart preparation and computerized analysis of functional data.

METHODS AND RESULTS

A controlled, experimental study was performed to compare cardiac function in the hearts of both transgenic mice with a 3-fold overexpression of beta ARK1 (n = 6; weight, 25 to 29 g) and littermate controls (n = 9; weight, 25 to 28 g). Preload-dependent cardiac output, contractility, heart rate, stroke work, and stroke volume were evaluated in the 2 groups before and after a 6-minute period of normothermic ischemia. Before ischemia, significant decreases were observed in all parameters of myocardial performance in beta ARK1 mice compared with control mice. After ischemia and reperfusion, significant decreases in cardiac function were observed in both experimental groups; however, significantly lower percentages of myocardial recovery occurred in beta ARK1 hearts compared with control hearts.

CONCLUSIONS

After global normothermic ischemia, significant decreases in cardiac function were observed in both beta ARK1 and control mice; however, significantly lower percentages of myocardial recovery occurred in beta ARK1 mice. These data suggest that myocardial beta ARK1 overexpression significantly impairs cardiac function in the setting of ischemia and reperfusion injury.

Comparison of open mitral commissurotomy with mitral valve replacement with or without chordal preservation in patients with mitral stenosis

BACKGROUND

Percutaneous balloon mitral valvuloplasty and durable mitral prostheses have made the role of open mitral commissurotomy (OMC) uncertain.

METHODS AND RESULTS

Results from the use of St Jude mitral valve replacement (SJMVR) were compared with those of the use of OMC in 312 consecutive patients with mitral stenosis between 1983 and the present. OMC and SJMVR patients were well matched for age, sex, and comorbidity except that SJMVR patients had more severe stenosis and were more likely to undergo concurrent aortic valve replacement. Compared with OMC, SJMVR without chordal preservation involved a longer pump time (158 +/- 81 versus 87 +/- 41 min, P < 0.05), more frequent in-hospital complications or death (57 of 219 [26%] versus 4 of 52 [8%], P < 0.01), and longer hospital stay (13 +/- 11 versus 10 +/- 6 days, P = 0.001). Preservation of chordae to at least 1 mitral valve leaflet decreased early morbidity and mortality rates of SJMVR to values comparable to those of OMC (3 of 41 [7%]). Survival was greater at 10 years for OMC versus SJMVR (86 +/- 5% versus 67 +/- 4%, P = 0.03). Ten-year freedom from cardiac events was not different between groups (49 +/- 9% for OMC versus 55 +/- 4% for SJMVR, P = 0.7). Freedom from subsequent mitral procedures at 10 years was better for SJMVR (96 +/- 2% versus 58 +/- 8%, P < 0.001).

CONCLUSIONS

In the modern era, SJMVR offers significantly greater durability than does OMC. Chordal preservation at the time of SJMVR may reduce perioperative complications to levels comparable to those of OMC.

Candidal anastomotic infection in lung transplant recipients: successful treatment with a combination of systemic and inhaled antifungal agents

Anastomotic infection is an uncommon but potentially life-threatening complication after lung transplantation. We recently encountered three lung transplant recipients with invasive candidal anastomotic infection. Two patients were admitted with dyspnea and fever, and one asymptomatic infection was detected on surveillance bronchoscopy. All three patients were treated similarly with a combination of intravenous amphotericin B, inhaled amphotericin B, and oral fluconazole. The combination of systemic and inhaled antifungal agents successfully treated all three cases of anastomotic infection.

Short-term clinical evaluation of post-operative sensitivity with bonded amalgams

PURPOSE

To compare the in vivo short-term post-operative sensitivity of teeth restored with amalgam using a bonded resin liner vs. teeth restored using a copal varnish liner.

MATERIALS AND METHODS

20 patients received Class I or Class II contralaterally paired restorations which were placed at the same appointment. All restorations were placed by the same operator using an identical technique except that, in each randomized pair, one was lined with an adhesive resin (Scotchbond Multi-Purpose Plus) while the other was lined with copal varnish. (Plastodent) Patients were provided visual analog scale response forms, instructed in their use, and requested to complete and return a form reporting their degree of sensitivity at baseline and on days 1, 3, 7, 14, and 30 post-operatively. Data from the response forms were analyzed for differences using a paired t-test.

RESULTS

A response rate of 90% (18/20) was achieved for the complete 30-day assessment. Increases in thermal sensitivity beyond baseline were seen in 13 of the 18 subjects involving 12 restorations lined with copal varnish and 10 lined with adhesive resin. Typically, sensitivity peaked on day 1 or day 3 and diminished to pre-operative levels by day 30. Only three subjects reported greater sensitivity at day 30 than at baseline. No significant difference in post-operative sensitivity was found between the two cavity lining materials at any post-operative interval.

Right ventricular function in orthotopic total atrioventricular heart transplantation

BACKGROUND

Total orthotopic heart transplantation was recently introduced into clinical practice as an alternative technique of orthotopic heart transplantation, adding bicaval and left and right pulmonary vein anastomoses to pulmonary artery and ascending aorta connection (total technique). The conventional technique (ventricular transplantation with atrioplasty) is compared with the total technique with particular emphasis on right ventricular performance.

METHODS

Forty-eight mongrel dogs (23 to 31 kg) were used for 12 total and 12 standard orthotopic heart transplantations. Right ventricular (RV) function and atrial systole were analyzed with the use of micromanometry, sonomicrometry, and ultrasonic flow probes (preload-independent RV recruitable stroke work, RVPRSW). Fourier analysis was used to calculate RV power and pulmonary vascular impedance.

RESULTS

There was no significant difference in cardiac ischemic and bypass times between the two groups. After transplantation, sinus rhythm was preserved after all total transplantations and after only one standard transplantation; no significant hemodynamic differences were observed. RVPRSW in the total group was conserved after transplantation; however, RVPRSW decreased by 39% (+/-8, p < .05) in the standard group. There was also a significant decrease in the rate of RV filling in the standard group after transplantation, suggesting decreased right atrial function. Pulmonary vascular impedance and RV power output were not significantly different after transplantation between the two groups.

CONCLUSIONS

Total atrioventricular transplantation is a feasible alternative and conserves normal sinus rhythm. Ischemic and bypass times were not significantly different when the superior vena cava anastomosis is performed last after the release of the aortic cross-clamp. The insignificant decrease in the rate of RV filling with the use of the total technique suggests conserved RV diastolic function after transplantation with less decreased RV function in the total group.

Hemodynamic and inotropic effects of milrinone after heart transplantation in the setting of recipient pulmonary hypertension

BACKGROUND

Right ventricular failure remains an important cause of early morbidity and death after heart transplantation and is commonly related to preexistent recipient chronic pulmonary hypertension, which occurs as a result of long-standing congestive heart failure. In this study, the hemodynamic and inotropic effects of milrinone were assessed after bicaval heart transplantation in the setting of monocrotaline pyrrole-induced recipient chronic pulmonary hypertension.

METHODS

Twenty dogs were used for 10 successfully completed transplantation experiments. Recipient animals underwent right atrial injection of 3 mg/kg monocrotaline pyrrole 4 months before transplantation. Hemodynamic and functional data were taken 1 hour after termination of cardiopulmonary bypass and after milrinone infusion. Myocardial function was assessed with load-insensitive means (preload-recruitable stroke work) and pulmonary vascular impedance was calculated with Fourier analysis.

RESULTS

At the time of transplantation, before cardiopulmonary bypass, pulmonary hemodynamic indexes in recipient animals were significantly increased when compared with donors and were further significantly increased after cardiopulmonary bypass. Two animals died after transplantation as a result of acute right ventricular failure. In surviving animals milrinone infusion led to significant increases in right ventricular function, which occurred in association with significant improvements in pulmonary vascular impedance and transpulmonary efficiency.

CONCLUSIONS

In the setting of monocrotaline pyrrole-induced recipient pulmonary hypertension, milrinone was associated with significant improvements in pulmonary vascular impedance, right ventricular function, and transpulmonary efficiency. These data suggest that milrinone is an effective means to improve right ventricular dysfunction and pulmonary vascular efficiency after bicaval heart transplantation in the setting of recipient chronic pulmonary hypertension.

The Ross procedure: shorter hospital stay, decreased morbidity, and cost effective

BACKGROUND

The Ross procedure has become an accepted and sometimes preferred alternative to mechanical aortic valve replacement. One criticism of the Ross procedure is that it may have a higher operative mortality, morbidity, and cost. Several groups have shown that this operation can be performed safely with less than 3% mortality. The issue of higher cost has not been resolved. In this retrospective study we compared a consecutive group of patients undergoing the Ross procedure with an age- and disease-matched group of patients who underwent mechanical aortic valve replacement.

METHODS

From 1993 to 1996, 22 consecutive adult patients (age range, 20 to 57 years; mean, 38 +/- 14 years) underwent the Ross procedure. Twenty-seven patients (age range, 17 to 57 years; mean, 41 +/- 10 years) underwent mechanical aortic valve replacement between 1991 and 1996. The hospital cost (in 1996 dollars) and postoperative length of stay were calculated for each patient using Transition I, a hospital-wide cost accounting system.

RESULTS

There was no hospital mortality in either group. The incidence of significant valve-related complication was 5% (1/22 patients) in the Ross procedure group and 22% (6/27 patients) in the mechanical valve group. There were two late deaths in the group with mechanical aortic valve replacement. The length of stay for the Ross procedure group was 5.9 +/- 2.1 days, versus 8 +/- 1.85 days for the mechanical valve group (p < 0.01). The mean hospital costs were not significantly different, $23,140 +/- $7,825 for the mechanical valve group and $23,226 +/- $6,960 for the group having the Ross procedure.

CONCLUSIONS

The data from this review demonstrate that the Ross procedure can be done safely, with short hospital stays, decreased morbidity, and costs comparable with those of standard mechanical aortic valve replacement in patients with isolated aortic valve disease.

Cardiopulmonary bypass time does not affect cerebral blood flow

BACKGROUND

A time-dependent decline in cerebral blood flow (CBF) has been reported in cardiac surgical patients despite stable pump flows and arterial carbon dioxide tension. Other studies have failed to support these hypothermic cardiopulmonary bypass (CPB) results, showing preservation of CBF during CPB. The purpose of the study was to define the influence of mildly hypothermic CPB duration on CBF.

METHODS

Cerebral blood flow was measured using xenon-133 washout and alpha-stat blood gas management during nonpulsatile CPB. Cerebral blood flow measurements were made after the initiation of CPB and near the end of bypass during pump flows of 2.4 L.min-1.m-2.

RESULTS

Fifty-two coronary artery bypass patients were studied. The average time between CBF measurements was 54 +/- 20 minutes (mean +/- standard deviation), with a range of 10 to 100 minutes. Temperature and arterial carbon dioxide tension were controlled: after the initiation of CPB, temperature was 35.5 degrees +/- 0.4 degree C and carbon dioxide tension was 37 +/- 2.8 mm Hg; whereas near the end of bypass temperature was 35.6 degrees +/- 0.5 degree C and carbon dioxide tension was 36 +/- 2.3 mm Hg. We found no correlation between CBF and time on CPB (p = 0.47; r = 0.101), in contrast to other studies suggesting that CPB duration may intrinsically affect CBF.

CONCLUSIONS

Our experimental results include the following: (1) during mildly hypothermic bypass, CBF does not decrease in relation to time and (2) cerebral flow-metabolism coupling is intact at 35 degrees C.

Pharmacological strategies for improving diastolic dysfunction in the setting of chronic pulmonary hypertension

BACKGROUND

Right ventricular (RV) hypertrophy is an adaptive process that occurs in the setting of chronic pulmonary hypertension (CPH) and can lead to alterations in normal RV diastolic properties. This study was designed to investigate the effects of NO and milrinone on RV diastolic dysfunction in the setting of CPH and RV hypertrophy by use of a canine model of monocrotaline pyrrole (MCTP)-induced CPH.

METHODS AND RESULTS

Sixteen mongrel dogs (22 to 24 kg) were used. Animals underwent percutaneous pulmonary artery (PA) catheterization to measure pulmonary hemodynamics before and 8 weeks after injection of 3 mg/kg MCTP (n=8) or placebo (control, n=8). Eight weeks after injection, all hearts were instrumented with a PA flow probe, sonomicrometric dimension transducers, and micromanometers. Data were collected at baseline and after both NO and milrinone administration. Diastolic properties were quantified by use of the end-diastolic pressure-volume relationship and the time constant of ventricular isovolumic relaxation. Eight weeks after injection, significant increases in the PA pressure and pulmonary vascular resistance were observed in MCTP dogs. Significant worsening of RV diastolic function occurred in association with significant increases in the ratio of RV dry weight to LV+septal dry weight. NO and milrinone administration both led to significant improvements in RV diastolic properties.

CONCLUSIONS

In the setting of MCTP-induced CPH, significant worsening of RV diastolic function was observed in association with significant increases in the ratio of RV dry weight to LV+septal dry weight, suggesting that these changes are partially due to RV hypertrophy. The significant improvement in RV diastolic properties after both NO and milrinone administration suggests that these agents may be effective forms of pharmacological therapy for improving RV diastolic dysfunction in the setting of CPH.

Complement-mediated pulmonary xenograft injury: studies in swine-to-primate orthotopic single lung transplant models

BACKGROUND

The pathogenesis of acute pulmonary xenograft injury has not yet been determined. The present study evaluates the role of complement in mediating pulmonary xenograft dysfunction by using cobra venom factor (CVF) to deplete recipient complement and transgenic swine, which express human regulators of complement activation (human decay-accelerating factor [hDAF] and hCD59).

METHODS

Fifteen orthotopic lung transplants were performed as follows: group I, swine-to-swine (n=5); group II, unmodified swine-to-baboon (n=3); group III, unmodified swine-to-(CVF treated) baboon (n=3); and group IV, hCD59/hDAF swine-to-baboon (n=4). Left pulmonary artery flow and pulmonary vascular resistance were measured at 30-min intervals. Serial lung biopsies were examined by light microscopy and immunofluorescence. The activation of complement was quantified by measurement of baboon plasma CH50 and C4 functional activity.

RESULTS

Group II xenotransplants ceased functioning within 30 min of reperfusion. Histopathologic ab normalities included erythrocyte/platelet aggregates and hemorrhagic pulmonary edema. Groups I and IV showed excellent function throughout. hDAF/hCD59 lungs (group IV) showed trace venular fibrin plugs and moderate loss of alveolar architecture. Pretreatment with CVF (group III) was ineffective in preventing xenograft injury.

CONCLUSIONS

These results characterize the fundamental features of discordant pulmonary xenotransplantation. Correction of the known defects in the regulation of heterologous complement activation was partially effective in preventing pulmonary xenograft dysfunction, suggesting that complement mediates, in part, some of the features of acute lung injury after discordant lung xenotransplantation.

The role of antibodies in acute vascular rejection of pig-to-baboon cardiac transplants

Long-term success in xenotransplantation is currently hampered by acute vascular rejection. The inciting cause of acute vascular rejection is not yet known; however, a variety of observations suggest that the humoral immune response of the recipient against the donor may be involved in the pathogenesis of this process. Using a pig-to-baboon heterotopic cardiac transplant model, we examined the role of antibodies in the development of acute vascular rejection. After transplantation into baboons, hearts from transgenic pigs expressing human decay-accelerating factor and CD59 underwent acute vascular rejection leading to graft failure within 5 d; the histology was characterized by endothelial injury and fibrin thrombi. Hearts from the transgenic pigs transplanted into baboons whose circulating antibodies were depleted using antiimmunoglobulin columns (Therasorb, Unterschleisshein, Germany) did not undergo acute vascular rejection in five of six cases. Biopsies from the xenotransplants in Ig-depleted baboons revealed little or no IgM or IgG, and no histologic evidence of acute vascular rejection in the five cases. Complement activity in the baboons was within the normal range during the period of xenograft survival. In one case, acute vascular rejection of a xenotransplant occurred in a baboon in which the level of antidonor antibody rose after Ig depletion was discontinued. This study provides evidence that antibodies play a significant role in the pathogenesis of acute vascular rejection, and suggests that acute vascular rejection might be prevented or treated by therapies aimed at the humoral immune response to porcine antigens.

Community respiratory viral infection in adult lung transplant recipients

STUDY OBJECTIVE

To define the epidemiology, clinical manifestations, and long-term complications of respiratory viral infections in adult lung transplant recipients.

DESIGN

Retrospective review of the records of 122 adult lung transplant recipients over a 5-year period at one institution.

RESULTS

Ten episodes of infection with respiratory syncytial virus, parainfluenza, influenza, or adenovirus were identified. All patients presented with symptoms of respiratory tract infection. Two patients died acutely and four patients subsequently had development of obliterative bronchiolitis (OB).

CONCLUSIONS

These data suggest community respiratory viral infections cause significant morbidity and mortality in lung transplant recipients. Further prospective studies are warranted to clarify the relationship between respiratory viral infection and OB and to define the optimal therapy for these viral infections.

Physiologic effects of extracellular superoxide dismutase transgene overexpression on myocardial function after ischemia and reperfusion injury

OBJECTIVE

Myocardial injury after ischemia and reperfusion may be mediated, in part, by oxygen-derived free radicals. In this study the protective effects of extracellular superoxide dismutase overexpression were directly assessed in the hearts of transgenic mice, after ischemia and reperfusion injury, using an isolated work-performing murine heart preparation and computerized analysis of functional data.

METHODS

A blinded study was performed to compare cardiac function in the hearts of both transgenic mice with a 3.5-fold overexpression of myocardial extracellular superoxide dismutase (n = 6, 22 to 26 gm) and littermate controls (n = 8, 22 to 26 gm). Preload-dependent cardiac output, contractility, heart rate, stroke work, and stroke volume were evaluated in the two groups before and after a 6-minute period of normothermic ischemia.

RESULTS

No differences were found between extracellular superoxide dismutase hearts and control hearts in any parameter of myocardial function before ischemia. After ischemia, decreases in cardiac output occurred in both groups; however, this decrease was larger in control mice compared with extracellular superoxide dismutase mice. A higher percentage of recovery was also observed in the contractility, heart rate, stroke work, and stroke volume of extracellular superoxide dismutase hearts compared with control hearts.

CONCLUSION

After global normothermic ischemia and subsequent reperfusion, decreases in cardiac function occurred in both extracellular superoxide dismutase and control mice; however, a higher percentage of recovery was observed in the extracellular superoxide dismutase overexpressed hearts. These data suggest that extracellular superoxide dismutase transgene overexpression significantly improves preservation of myocardial function after ischemia and reperfusion injury.

Lung transplantation for Williams-Campbell syndrome

Williams-Campbell syndrome is a rare disorder characterized by a deficiency of cartilage in subsegmental bronchi leading to distal airway collapse and bronchiectasis. We report the first case of lung transplantation in a patient with end-stage lung disease secondary to Williams-Campbell syndrome. Although the patient did not have proximal airway collapse prior to transplantation, his posttransplant course was complicated by the development of bronchomalacia of the right and left mainstem bronchi. The patient experienced recurrent pulmonary infections and died of bacterial pneumonia 1 year after transplantation. Autopsy revealed cartilage deficiency in both right and left mainstem bronchi. A hypothesis may be made that a combination of proximal cartilage deficiency and posttransplant airway ischemia led to the development of bronchomalacia after lung transplantation. Thus, in contrast to previous reports, the cartilage deficiency in Williams-Campbell syndrome can involve both proximal and distal airways. Consequently, bilateral sequential lung transplantation may not be an effective therapeutic option in patients with this syndrome.

Lung transplantation at Duke University Medical Center

Lung transplantation is a viable therapy for patients with a variety of end-stage lung diseases. Our active program now includes over 200 lung transplant operations with acceptable one- and 3-year survival rates of 78% and 61%. A major focus of clinical research at this institution is to design strategies to prevent the development of chronic allograft dysfunction. Our preliminary work in this regard has been encouraging. In addition, a major research focus has been to design protocols to prevent the development of posttransplant infections. Our work with aerosolized ABLC represents a major advance at our center, and additional randomized prospective studies are ongoing to define the optimal antifungal prophylaxis after transplantation. Ongoing clinical and basic research at Duke and elsewhere should continue to advance the field of clinical transplantation and ultimately lead to more acceptable long-term outcomes for lung allograft recipients.

A clinical evaluation of the analgesic efficacy of preoperative administration of ketorolac and dexamethasone following surgical removal of third molars

The purpose of this study was to compare the postoperative analgesic efficacy of the presurgical intravenous administration of a steroid (dexamethasone), a nonsteroidal anti-inflammatory drug (ketorolac), and a combination of the two medications. These drugs were administrated preoperatively, and their analgesic effects were assessed following the removal of four third molars using intravenous sedation (Fentany/Midazolam) and local anesthetic (2% lidocaine with 1:100,000 epinephrine). Thirty-four patients were randomly assigned to one of four groups: Group I (control), saline; Group II, 30 mg ketorolac; Group III, 8 mg dexamethasone; and Group IV, 30 mg ketorolac + 8 mg dexamethasone. Pain was assessed with the Heft-Parker graphic pain rating scale; the initial survey was completed preoperatively. The teeth were surgically removed by one of four oral and maxillofacial surgeons. Following surgery and initial recovery, the patients completed the second survey and were then admitted for overnight observation. The patients completed the remaining pain rating scales at 2-hr intervals for 12 hr. The last survey was completed at discharge (24 hr postoperatively). A postoperative narcotic analgesic was provided upon request (Tylenol 3). Pain data were assessed using one-way analysis of variance and the Duncan multiple range test (alpha = 0.05). At all postoperative intervals, the greatest pain scores were recorded in the control group. Statistically significant differences in pain scores were found at the 4-, 6-, 8-, and 10-hr postoperative intervals. At the 2-hr postoperative interval, pain had increased in all groups, but no differences were found among the groups. At the 4- and 6-hr interval, pain levels in Group I were significantly greater than those in Group II and Group IV, with Group III and IV not significantly different from Group II. At 10 hr, pain levels in the saline group were significantly greater than those in all the other groups. At all intervals, the only significant differences detected were found between the control group and the experimental groups; no significant differences were found at any point among any of the experimental groups. The relationship between the number of doses of narcotic medication taken postoperatively, and the preoperative intravenous regimen was assessed with a Kruskal-Wallis test. No significant difference was found among groups with respect to the need for postoperative pain medication (P > 0.05). Postoperative analgesia following third molar surgery was enhanced in the first 10 hr with the preoperative administration of ketorolac. The addition of dexamethasone did not improve the analgesic effect.

Total respiratory support from swine lungs in primate recipients

The use of nonhuman lung donors, such as swine, has the potential to provide an unlimited supply of organs. However, hyperacute rejection has prevented pulmonary xenotransplantation.

OBJECTIVE

Our aim was to test the hypothesis that immunodepletion by pretransplantation swine lung perfusion will prevent hyperacute swine-to-primate pulmonary xenograft rejection and allow for a functional swine pulmonary xenograft.

METHODS

Seven baboons underwent left pneumonectomy followed by orthotopic transplantation of the swine left lung. Four baboons received immunodepletion by perfusion with swine lungs before transplantation, and three received no treatment before transplantation.

RESULTS

After transplantation, pulmonary xenografts from immunodepleted baboons had a low pulmonary vascular resistance and a high pulmonary blood flow compared with control animals, which had a high pulmonary vascular resistance and a low pulmonary blood flow. After 60 minutes of reperfusion, three of four immunodepleted animals also tolerated complete occlusion of the right pulmonary artery, with the baboon relying completely on the swine pulmonary xenograft for respiratory function for 11 hours. Pathologic analysis of peripheral lung biopsy specimens taken from control lungs displayed alveolar disruption and hemorrhage within small vessels, whereas swine lungs transplanted into immunodepleted baboons displayed little histologic evidence of injury. Furthermore, pulmonary xenografts transplanted into immunodepleted baboons demonstrated excellent respiratory function and adequate hemodynamics during occlusion of the right pulmonary artery.

CONCLUSION

Hyperacute pulmonary xenograft rejection can be prevented by pretransplantation swine lung perfusion. Swine pulmonary xenografts can provide complete respiratory support in primates when rejection is prevented.

Pulmonary vascular impedance and recipient chronic pulmonary hypertension following cardiac transplantation

STUDY OBJECTIVES

Recipient chronic pulmonary hypertension (CPH), secondary to long-standing congestive heart failure, represents a significant risk factor for right ventricular (RV) dysfunction following orthotopic cardiac transplantation (TX). This study was designed to characterize the changes occurring in pulmonary hemodynamics, pre-TX and post-TX, using Fourier analysis, a canine model of bicaval TX, and monocrotaline pyrrole (MCTP)-induced recipient CPH.

DESIGN

Prospective, controlled study.

SETTING

Experimental laboratory.

PARTICIPANTS

Twenty adult male mongrel dogs (23 to 26 kg).

INTERVENTIONS

Recipients underwent pulmonary artery injection of 3 mg/kg MCTP 4 months pre-TX. On the day of TX, donor hearts were instrumented with an ultrasonic flow probe and micromanometers. Harmonic derivation of functional data was achieved with Fourier analysis.

MEASUREMENTS AND RESULTS

At the time of TX, significant increases were observed in the mean pulmonary artery pressure and pulmonary vascular resistance of recipient animals in comparison to donors, which were further significantly increased following the termination of cardiopulmonary bypass. Significant increases were also observed in the input resistance, characteristic impedance, and RV hydraulic power post-TX compared to pre-TX, and occurred in association with a significant decrease in the transpulmonary efficiency.

CONCLUSIONS

In the setting of MCTP-induced recipient CPH donor hearts were exposed to significant alterations in cardiopulmonary hemodynamics following bicaval TX. Pulmonary blood flow is maintained by a significantly higher energy expenditure by the RV, but at a lower level of efficiency. This experimental model may provide a useful means by which to evaluate therapeutic options to better manage cardiopulmonary hemodynamics in order to prevent RV failure following TX in the setting of recipient CPH.

Mycoplasma hominis pneumonia complicating bilateral lung transplantation: case report and review of the literature

Mycoplasma hominis is a commensal of humans. The organism has been predominantly associated with infections of the genitourinary tract. Extragenital infections have been described in neonates, in women during the postpartum period, and in immunocompromised patients. Pneumonia caused by M. hominis is very rare. This report describes the development of M. hominis pneumonia in a lung transplantation recipient and underscores the difficulty in establishing the correct diagnosis and the need for early and aggressive treatment with appropriate antimicrobial agents to insure a good outcome.