Effects of prolonged partial liquid ventilation, high frequency ventilation and conventional ventilation on gas exchange and lung pathology in newborn surfactant-depleted piglets

Partial liquid ventilation (PLV) improves oxygenation in various animal models of respiratory insufficiency. The aim of this study was to compare the effects of conventional ventilation (CV), high frequency oscillatory ventilation (HFOV), and PLV combined with CV or HFOV on gas exchange and histopathology. Thirty anaesthetised newborn piglets (mean weight 1.94 kg, age 1-3 days) were randomized in five groups of six animals: CV, CV + surfactant (S), HFOV+S, PLV/CV, and PLV/HFOV. Thirty min after lung injury had been induced with repeated saline lavage, specific ventilatory treatment was initiated. Three animals of the CV group died within the 24 h study period, whereas none died in any of the other groups. The oxygenation index (OI) and the PaO2/FIO2 ratio improved significantly within 30 min in all groups, but not in the CV group. After 24 h all oxygenation parameters were better in the PLV groups than in CV or CV+S (P < 0.05). No differences in gas exchange were noted between HFOV+S and PLV/CV. The combination of PLV with HFOV led to an increased PaO2/FIO2 ratio when compared with PLV/CV and with HFOV+S (P < 0.05). All PLV treated animals had significantly less lung injury in the upper and lower lobes compared with gas-ventilated animals by histologic semi-quantitative lung injury score (P < 0.01) and in the lower lobes by morphometry (P < 0.001). In conclusion, HFOV+S and PLV either with CV or HFOV are effective techniques to provide adequate gas exchange in S-deficient lungs compared with CV with and without S. However, lung injury was significantly improved in both PLV treated groups compared with HFOV+S and the CV groups.

Efficient synthesis of a porphyrin-N-tripod conjugate with covalently linked proximal ligand: toward new-generation active-site models of cytochrome c oxidase

[formula: see text] A new-generation cytochrome c oxidase active-site model compound (4) featuring both a trisimidazolyl moiety and a proximal base has been designed and efficiently synthesized. During this study, a facile method based on the chemistry of a 4-magnesioimidazole derivative to synthesize 4-imidazolyl-containing tripodal ligands (7) has been developed.

Intravenous immunoglobulin reduces anti-HLA alloreactivity and shortens waiting time to cardiac transplantation in highly sensitized left ventricular assist device recipients

BACKGROUND

Recipients of left ventricular assist devices (LVADs) develop prominent B-cell hyperreactivity. We investigated the influence of anti-HLA antibodies on waiting time to cardiac transplantation in LVAD recipients and compared the effects of 2 immunomodulatory regimens on anti-HLA serum reactivity.

METHODS AND RESULTS

Fifty-five previously nonsensitized LVAD recipients of a TCI device implanted between 1990 and 1996 were studied. Patients with anti-HLA antibodies received monthly courses of either intravenous immunoglobulin (IVIg) or plasmapheresis, in conjunction with cyclophosphamide. The effects of these regimens on anti-HLA alloreactivity and waiting time to transplantation were then determined by Kaplan-Meier log-rank statistics, nonparametric Wilcoxon rank-sum test, and Student's t test. Prolongation in transplant waiting time was related to serum IgG anti-HLA class I alloreactivity. Infusion of IVIg (2 g/kg) caused a mean reduction of 33% in anti-HLA class I alloreactivity within 1 week. Waiting time to transplantation was significantly reduced by IVIg therapy and subsequently approximated that in nonsensitized patients. Side effects of IVIg (2 g/kg) were minimal and related primarily to immune complex disease. Although plasmapheresis caused a similar reduction in alloreactivity to IVIg, this effect was achieved after longer treatment. Moreover, plasmapheresis was associated with an unacceptably high frequency of infectious complications. In patients resistant to low-dose (2 g/kg) IVIg therapy, high-dose (3 g/kg) IVIg was effective in reducing alloreactivity but was associated with a high incidence of reversible renal insufficiency.

CONCLUSIONS

These results indicate that IVIg is an effective and safe modality for sensitized recipients awaiting cardiac transplantation, reducing serum anti-HLA alloreactivity and shortening the duration to transplantation. The therapeutic and safety profile of IVIg would appear to be superior to plasmapheresis.

Low incidence of myocardial recovery after left ventricular assist device implantation in patients with chronic heart failure

BACKGROUND

Mechanical, histological, and biochemical improvement has been described in patients after left ventricular assist device (LVAD) support. Explantation of the LVADs without heart transplantation has been described in selected patients who received this therapy as a bridge to transplantation.

METHODS AND RESULTS

A retrospective review of patients receiving a mechanical bridge to transplantation at Columbia Presbyterian Hospital after July 21, 1991, was performed to determine the incidence of patients in whom the device was successfully explanted. From August 1, 1996, to February 1, 1998, we prospectively attempted to identify potential explant candidates by the use of exercise testing. During this time, we recruited 39 consecutive patients after insertion of the Thermo Cardiosystems vented electric device to participate in the following study. Approximately 3 months after device implantation, a maximal exercise test with hemodynamic monitoring and respiratory gas analysis was performed with the LVAD in the automated mode. The electric device was interfaced with a pneumatic console such that the rate could be decreased to 20 cycles/min. Hemodynamic measurements were recorded as the device rate was decreased. A repeat exercise test was then performed if the patient remained hemodynamically stable. A retrospective chart review of 111 LVAD recipients at our institution identified only 5 successful explant patients. Eighteen of the 39 patients were studied. Fifteen patients exercised with maximal device support. At peak exercise, VO2 averaged 14.5+/-3.6 mL. kg-1. min-1; LVAD flow, 8.0+/-1.3 L/min; Fick cardiac output, 11.4+/-3.3 L/min; and pulmonary capillary wedge pressure, 13+/-4 mm Hg. Seven patients remained normotensive and could exercise at a fixed rate of 20 cycles/min. In these patients, peak VO2 declined from 17.3+/-3.9 to 13.0+/-6.1 mL. kg-1. min-1. In one of these patients, the device was explanted.

CONCLUSIONS

Significant myocardial recovery after LVAD therapy in patients with end-stage congestive heart failure occurs in a small percentage of patients. Most of these patients have dilated cardiomyopathy. Exercise testing may be a useful modality to identify those patients in whom the device can be explanted.

Comparison of exercise performance in patients with chronic severe heart failure versus left ventricular assist devices

BACKGROUND

Left ventricular assist devices (LVADs) are frequently used as a bridge to cardiac transplantation and may be useful as long-term therapy. The purpose of this study was to compare the exercise performance of LVAD patients with that of ambulatory heart failure patients.

METHODS AND RESULTS

Exercise testing with hemodynamic and respiratory gas measurements was performed in 65 congestive heart failure (CHF) patients (age 53+/-10 years) and 20 LVAD patients (age 49+/-8 years). Peak Vo2 was significantly higher in the LVAD than the CHF patients (CHF, 12+/-3; LVAD, 15. 9+/-3.8 mL . kg-1 . min-1; P<0.001), as was the Vo2 at the anaerobic threshold (CHF, 8.1+/-2.1; LVAD, 12.2+/-2.9 mL . kg-1 . min-1; P<0.001). At rest, mean arterial blood pressure (CHF, 87+/-11; LVAD, 94+/-9 mm Hg) and cardiac output (CHF, 4+/-1; LVAD, 4. 9+/-0.9 L/min) were increased, whereas mean pulmonary artery pressure (CHF, 28+/-11; LVAD, 18+/-4 mm Hg) and pulmonary artery wedge pressure (CHF, 16+/-10; LVAD 5+/-3 mm Hg) were reduced (all P<0.01). At peak exercise, heart rate (CHF,125+/-24; LVAD, 148+/-24 bpm), blood pressure (CHF, 87+/-14; LVAD,96+/-12 mm Hg), and cardiac output (CHF, 7.6+/-2.2; LVAD, 11.2+/-2.6 L/min) were higher (all P<0. 01), whereas mean pulmonary artery pressure (CHF, 48+/-12; LVAD, 30+/-5 mm Hg) and mean pulmonary capillary wedge pressure (CHF, 31+/-11; LVAD, 14+/-6 mm Hg) were lower in the LVAD group (both P<0. 001). In the LVAD patients, Fick cardiac output was higher than LVAD flow sensor value measurements (Fick, 11.6+/-2.5; LVAD, 8.1+/-1.2 L/min; P<0.001).

CONCLUSIONS

Hemodynamic measurements at rest and during exercise are significantly improved in patients with devices compared with those in ambulatory heart failure patients awaiting cardiac transplantation. Similarly, the exercise capacity of device patients is better than that of transplant candidates and in the majority of patients is similar to that of patients with mild CHF.

High-resolution restriction maps of bacterial artificial chromosomes constructed by optical mapping

Large insert clone libraries have been the primary resource used for the physical mapping of the human genome. Research directions in the genome community now are shifting direction from purely mapping to large-scale sequencing, which in turn, require new standards to be met by physical maps and large insert libraries. Bacterial artificial chromosome libraries offer enormous potential as the chosen substrate for both mapping and sequencing studies. Physical mapping, however, has come under some scrutiny as being "redundant" in the age of large-scale automated sequencing. We report the development and applications of nonelectrophoretic, optical approaches for high-resolution mapping of bacterial artificial chromosome that offer the potential to complement and thereby advance large-scale sequencing projects.

Gender and savings in rural India

"In this study we use data from rural India to examine the impact of the birth of a boy relative to the birth of a girl (i.e., the ¿gender shock') on the savings, consumption and income of rural Indian households. We find that the gender shock reduces savings for medium and large farm households, although there is no evidence that the shock affects savings for the landless and the small farm households. We also estimate the effect of the shock on income and consumption for the former group in order to determine the source of the drop in savings."

Effect of Hispanic ethnicity on interpretation of maternal serum screening

Maternal serum concentrations of alpha-fetoprotein (MSAFP), unconjugated estriol (uE3) and human chorionic gonadotropin (hCG) were measured in the sera of 3,046 Hispanic women and of 15,154 Caucasian women from gestational weeks 14 through 20 between January 1990 and December 1995. Median values for analytes were calculated for each gestational week and the two ethnic groups compared. Our findings indicate that the median values for Hispanics are lower for MSAFP and hCG, but higher for estriol. These differences are not accounted for by differences in median weights of the two ethnic groups. Although these results would suggest that Hispanic women at risk for a fetus with a neural tube defect (NTD) may be missed when cut-offs derived from a Caucasian population are used, in fact, that was not the case in our screening population. However, a disproportionate number of Hispanic women may be identified with an abnormal serum screening test unrelated to a risk for neural tube defects. This does not infer that detection rates are different across different ethnic groups since other factors are involved. Adjustment of medians for Hispanic ethnicity may have a small but significant effect, especially with regard to low values.

Treatment of hairy-cell leukemia with cladribine: response, toxicity, and long-term follow-up

PURPOSE

To analyze initial and long-term outcomes after treatment of patients with active hairy-cell leukemia (HCL) with a single cycle of cladribine (2-CdA).

PATIENTS AND METHODS

Forty-nine patients with active HCL were treated with 2-CdA by continuous intravenous infusion at 0.1 mg/kg/d for a total of 7 days at the Long Island Jewish Medical Center between September 1990 and August 1992. Here we report on all patients followed-up until April 1996.

RESULTS

At 3 months after treatment, complete response (CR) occurred in 37 patients (76%) and partial response (PR) occurred in 12 patients (24%), for an overall response rate of 100% (95% confidence interval, 94% to 100%). At a median follow-up of 55 months, the relapse-free survival is 80% and overall survival is 95%. Ten patients (20%) have relapsed. Of the 26 patients in whom lymphocyte phenotyping was performed, four were found to have a CD25-negative phenotype. All four of these patients had PRs only and all relapsed. Eight patients have been re-treated with 2-CdA, and all achieved at least a partial remission; two of these have already relapsed with remission durations of less than 1 year. Five second malignancies have occurred in four patients.

CONCLUSION

With a median follow-up of more than 4 years, 39 patients (80%) continue in remission. Only two deaths have occurred. A CD25-negative phenotype may predict for a poorer response to 2-CdA. Patients who relapse may be re-treated with 2-CdA, but subsequent remissions may be of shorter duration. There has not been a markedly increased incidence of second malignancies or late opportunistic infections.

Activation of coagulation and fibrinolytic pathways in patients with left ventricular assist devices

Left ventricular assist devices have provided successful supportive therapy for patients awaiting cardiac transplantation for extended periods of time. Although thromboembolic events have complicated support with these devices, the HeartMate left ventricular assist device developed by Thermo Cardiosystems, Inc., Woburn, Massachusetts, was specifically designed with a textured blood-contacting surface to minimize this risk. Clinical experience with this device has been encouraging, inasmuch as minimal thromboembolic complications have occurred despite the absence of anticoagulation. The coagulation and fibrinolytic pathways in these individuals were investigated to better understand the hematologic status of patients treated with the Thermo Cardiosystems device. Despite apparently normal prothrombin and activated partial thromboplastin times, as well as platelet counts, evidence of significant thrombin generation and fibrinolysis was present. To eliminate underlying cardiac failure as the responsible factor for these abnormalities, we made similar measurements in patients with end-stage heart failure who were not supported by an assist device or anticoagulation. These measurements revealed no evidence of thrombin generation or fibrinolysis. These data demonstrate that patients supported with a left ventricular assist device, while successfully sustained without systemic anticoagulation, nevertheless have evidence of activation of coagulation. These phenomena appear to be related to the presence of the device rather than to the underlying cardiac abnormalities. Although procoagulant and fibrinolytic pathways are apparently balanced in these patients, these data underscore the potential for the development of bleeding or thrombosis in clinically relevant settings.

Relapse of hairy cell leukemia after 2-chlorodeoxyadenosine: long-term follow-up of the Northwestern University experience

Although 2-chlorodeoxyadenosine (2-CdA) is effective in inducing complete remissions (CRs) in the majority of patients with hairy cell leukemia (HCL), neither the actual relapse rate, the clinical factors that may predict relapse, the long-term outcome, nor the response rate to re-treatment at relapse has been clearly determined. Fifty-two consecutive patients with previously untreated or treated HCL were treated with 2-CdA at a dose of 0.1 mg/kg/d by continuous intravenous infusion for 7 days. Of 50 assessable patients, 40 (80%) achieved CR, and 9 (18%) achieved partial remission (PR). A total of 7 patients (14%) have relapsed, at a median duration of 24 months (range, 12 to 44). Of the 7 relapsed patients, 5 were re-treated with a second cycle of 2-CdA; 2 achieved a second CR and 3 attained a PR. The progression-free survival (PFS) rate is 72% at 4 years for all 52 patients and 83% for patients achieving CR. The overall survival (OS) rate is 86% at 4 years. Only prior therapy was predictive of relapse. The majority of patients achieve durable CRs with a single cycle of 2-CdA. The relapse rate is low and the long-term prognosis is excellent. The few patients who relapse can attain second remissions after re-treatment with 2-CdA.

Pharmacokinetic study of oral and bolus intravenous 2-chlorodeoxyadenosine in patients with malignancy

PURPOSE

This study was designed to evaluate the absolute bioavailability (F value) of 2-chlorodeoxyadenosine (cladribine; 2-CdA) after multiple oral administrations, and the intersubject variability after oral and 2-hour intravenous (IV) administration schedules in patients with malignancy.

PATIENTS AND METHODS

Patients with advanced malignancies were eligible. There were two treatment cycles; during cycle 1, patients received 2-CdA solution at 0.28 mg/kg/d orally under fasting conditions for 5 consecutive days concomitantly with omeprazole, and 4 weeks later during cycle 2 patients received 2-CdA as a 2-hour IV infusion of 0.14 mg/kg/d for 5 consecutive days. Serial blood samples for 2-CdA plasma levels were obtained after drug administrations on days 1 and 5 during each treatment cycle.

RESULTS

Ten patients completed cycles 1 and 2. The F value of oral 2-CdA measured on days 1 and 5 was 37.2% and 36.7%, respectively. For both oral and IV multiple administrations, there was no significant accumulation in maximum concentration (Cmax), and the intersubject variabilities (coefficient of variation [CV], approximately 40%) in Cmax and area under the concentration-time curve from 0 to 24 hours [AUC(0-24)] values were comparable for both routes on days 1 and 5. A three-compartment open model was applied to the plasma concentration data after oral and IV administrations and resulted in good agreement between observed and simulated concentration-time profiles. Neutropenia was the principal adverse event observed when 2-CdA was administered orally and IV.

CONCLUSION

The F value of 2-CdA after oral administration was approximately 37% and there were no cumulative differences in bioavailability observed on multiple dosing of the drug. The absorption and disposition characteristics of oral 2-CdA were linear and predictable with this dosing regimen.

Interaction between the phosphotyrosine binding domain of Shc and the insulin receptor is required for Shc phosphorylation by insulin in vivo

Stimulation of the insulin receptor (IR) results in tyrosine phosphorylation of the intermediate molecules insulin receptor substrate-1 (IRS-1), IRS-2, and Shc, which then couple the IR to downstream signaling pathways by serving as binding sites for signaling molecules with SH2 domains. It has been proposed that direct binding of IRS-1, IRS-2, and Shc to an NPX-Tyr(P) motif in the juxtamembrane region of the IR is required for tyrosine phosphorylation of these molecules by the IR. In this regard, Shc and IRS-1 contain domains that are distinct from SH2 domains, referred to as the phosphotyrosine binding (PTB) or phosphotyrosine interaction (PI) domains, which bind phosphotyrosine in the context of an NPX-Tyr(P) motif. To further clarify the role of the Shc PTB/PI domain, we identified a mutation in this domain that abrogated binding of Shc to the IR in vitro. Interestingly, this mutation completely abolished Shc phosphorylation by the IR in vivo whereas mutation of the arginine in the FLVRES motif of the Shc SH2 domain did not affect Shc phosphorylation by insulin. In addition, we identified specific amino acids on the IR that are required for the IR to stimulate Shc but not IRS-1 phosphorylation in vivo. As with the PTB/PI domain Shc mutant, the ability of these mutant receptors to phosphorylate Shc correlates with the binding of the PTB/PI domain of Shc to similar sequences in vitro. These findings support a model in which binding of the PTB/PI domain of Shc directly to the NPX-Tyr(P) motif on the IR mediates Shc phosphorylation by insulin.

Selection and treatment of candidates for heart transplantation. A statement for health professionals from the Committee on Heart Failure and Cardiac Transplantation of the Council on Clinical Cardiology, American Heart Association

Improved outcome of heart failure in response to medical therapy, coupled with a critical shortage of donor organs, makes it imperative to restrict heart transplantation to patients who are most disabled by heart failure and who are likely to derive the maximum benefit from transplantation. Hemodynamic and functional indexes of prognosis are helpful in identifying these patients. Stratification of ambulatory heart failure patients by objective criteria, such as peak exercise oxygen consumption, has improved ability to select appropriate adult patients for heart transplantation. Such patients will have a poor prognosis despite optimal medical therapy. When determining the impact of individual comorbid conditions on a patient's candidacy for heart transplantation, the detrimental effects of each condition on posttransplantation outcome should be weighed. Evaluation of patients with severe heart failure should be done by a multidisciplinary team that is expert in management of heart failure, performance of cardiac surgery in patients with low left ventricular ejection fraction, and transplantation. Potential heart transplant candidates should be reevaluated on a regular basis to assess continued need for transplantation. Long-term management of heart failure should include continuity of care by an experienced physician, optimal dosing in conventional therapy, and periodic reevaluation of left ventricular function and exercise capacity. The outcome of high-risk conventional cardiovascular surgery should be weighed against that of transplantation in patients with ischemic and valvular heart disease. Establishment of regional specialized heart failure centers may improve access to optimal medical therapy and new promising medical and surgical treatments for these patients as well as stimulate investigative efforts to accelerate progress in this critical area.

The GTP-binding protein Rac does not couple PI 3-kinase to insulin-stimulated glucose transport in adipocytes

BACKGROUND

In insulin-sensitive cells, such as adipocytes and skeletal muscle, the activation of phosphoinositide 3-kinase (PI 3-kinase) is thought to be critical in allowing insulin to stimulate both the uptake of glucose and the translocation of a specialized glucose transporter, GLUT4, to the plasma membrane. However, the downstream mediators that couple PI 3-kinase to GLUT4 translocation are still not known. Recent studies have shown that the GTP-binding protein Rac mediates some of the biological effects of PI 3-kinase, and these findings have led to the suggestion that Rac may be a common mediator for a variety of responses mediated by PI 3-kinase. To determine whether Rac couples PI 3-kinase to glucose uptake in adipocytes, we produced 3T3-L1 cells expressing either a constitutively active Rac1 (V12 Rac1, containing a valine residue at position 12) or a dominant-inhibitory Rac1 (N17 Rac1, containing an asparagine residue at position 17).

RESULTS

The stable expression of both V12 Rac1 and N17 Rac1 led to observable phenotypes in 3T3-L1 cells; expression of V12 Rac1 resulted in constitutive formation of lamellipodia and constitutive activation of the cJun-N-terminal kinase (JNK), whereas expression of N17 Rac1 inhibited the insulin-stimulated formation of lamellipodia. However, neither basal glucose uptake nor insulin-stimulated glucose uptake was affected by the expression of either mutant Rac protein. In addition, expression of V12 Rac1 did not reverse the inhibition of insulin-stimulated glucose uptake caused by the PI 3-kinase inhibitor wortmannin.

CONCLUSIONS

These findings provide direct evidence that PI 3-kinase does not use Rac to couple the insulin receptor to glucose uptake in adipocytes. Furthermore, the finding that Rac does not mediate glucose uptake in response to insulin is consistent with the idea that PI 3-kinase couples to a variety of different effector molecules in cells, and suggests that some of the specificity in the biological responses elicited by PI 3-kinase may be mediated by the activation of different effector molecules.