Search

OBJECTIVES The aim of this study was to evaluate whether additional cusp interventions and valve types affect aortic valve-related reoperation and mortality rates after the David procedure. METHODS Between 1997 and 2018, a total of 449 patients {372 males; mean age 54.2 [standard deviation (SD) 15.2] years, range: 12.7–79.9 years} underwent elective valve-sparing aortic root replacement (David procedure) for aortic regurgitation and were prospectively followed up clinically and echocardiographically. RESULTS The follow-up was 94% complete. Cumulative follow-up time was 2268 patient-years [mean follow-up time 5.1 (4.3 SD) years]. Thirty-day mortality was 2.2% (n = 10). Late (>30 days) survival did not differ from that of the age- and gender-matched general population. Freedom from reoperation in patients without additional cusp reconstruction was 94% [95% confidence interval (CI) 91–98] and 92% (95% CI 88–97) at 5 and 10 years, respectively, which was not significantly different (P = 1) for patients who did require additional cusp reconstruction 98% (95% CI 95–100) and 89% (95% CI 81–99). In patients with tricuspid aortic valves (n = 338), freedom from reoperation was 96% (95% CI 94–99) and 93% (95% CI 88–97) at 5 and 10 years, respectively. Patients with bicuspid aortic valves (n = 111) had a freedom from reoperation of 94% (95% CI 89–99) at 5 years and 88% (95% CI 79–98) at 10 years (P = 0.021 for the comparison to tricuspid aortic valve). Overall, 23 patients (5%; 1%/patient-year) required reoperation with a mean interval of 4.5 (4.8 SD) months. CONCLUSIONS The David procedure revealed low mid-term reoperation risk and excellent survival independent of adjunctive cusp interventions/valve morphology and is comparable with that of the age- and gender-matched general population.

Background: Surgical treatment of young and middle-aged patients suffering from aortic valve disease remains an unresolved issue due to the limited durability of bioprosthetic heart valve replacements and the valve-related morbidity of patients with mechanical valve substitutes. Theoretically, the “living valve” principle of the Ross operation may represent a potentially viable solution to this dilemma. In this paper, we report on the surgical techniques of the Ross procedure and present long-term post-operative outcomes using the reinforced full-root technique. Methods: From 1995 to 2020, a total of 832 consecutive patients (mean age, 43.4±13.7 years; 617 males) underwent a Ross operation using the full-root technique. Patients were prospectively monitored with clinical and echocardiographic follow-up. Total follow-up was 9,046 patients-years and was 92% complete. Mean-follow-up was 10.9±6.9 years (range, 0–24.9 years) Results: Survival at twenty years was 92% (95% CI: 90–94%). Freedom from autograft or right ventricle to pulmonary artery connection reoperation at twenty years was 79% (95% CI: 74–85%). Eighty-nine pulmonary autograft reoperations had to be performed in eighty patients; salvage of the pulmonary autograft could be performed in forty-six of them. Fifty-seven patients required sixty-three reoperations on the right ventricle to pulmonary artery connection. Major cerebral bleeding occurred in one patient and neurological events in seventeen patients, respectively. Conclusions: Over a follow-up interval of up to twenty-five years, the Ross operation with the reinforced full-root technique demonstrated excellent survival in young and middle-aged patients. The rate of pulmonary autograft and right ventricular outflow graft reoperations were low in this patient subset. Therefore, the Ross operation with the reinforced full-root technique represents an enduring and valid treatment option in young and middle-aged patients suffering from aortic valve disease.

Summary Many broadly neutralizing antibodies (bnAbs) against HIV-1 recognize and/or penetrate the glycan shield on native, virion-associated envelope glycoprotein (Env) spikes. The same bnAbs also bind to recombinant, soluble trimeric immunogens based on the SOSIP design. While SOSIP trimers are close structural and antigenic mimics of virion Env, the extent to which their glycan structures resemble ones on infectious viruses is undefined. Here, we compare the overall glycosylation of gp120 and gp41 subunits from BG505 (clade A) virions produced in a lymphoid cell line with those from recombinant BG505 SOSIP trimers, including CHO-derived clinical grade material. We also performed detailed site-specific analyses of gp120. Glycans relevant to key bnAb epitopes are generally similar on the recombinant SOSIP and virion-derived Env proteins, although the latter do contain hotspots of elevated glycan processing. Knowledge of native versus recombinant Env glycosylation will guide vaccine design and manufacturing programs., Graphical Abstract, Highlights • HIV envelope glycans are central features of broadly neutralizing antibody epitopes • Recombinant mimetics of the HIV virus trimer are vaccine candidates • Glycosylation of a leading trimer immunogen is similar to that of infectious virus, Struwe et al. present site-specific analyses of N-glycosylation sites on HIV-1 envelope glycoproteins from an infectious virus and a recombinant trimer mimic. The structural and antigenic details of the glycan shield will be valuable for designing next-generation immunogens and understanding virus neutralization by broadly active antibodies.

An incomplete understanding of native human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) envelope glycoproteins (Envs) impedes the development of structural models of Env and vaccine design. This shortcoming is due in part to the low number of Env trimers on virus particles. For SIV, this low expression level can be counteracted by truncating the cytoplasmic tail (CT) of Env. CT truncation has been shown to increase Env incorporation into the virion and is commonly used in vaccine and imaging studies, but its effects on viral antigenicity have not been fully elucidated. To study the effects of a CT truncation of Env in viruses in similar genetic contexts, we introduced stop codons into the CT of a SIVsmE660 molecular clone and two neutralizing antibody (NAb) escape variants. These viruses shared 98% sequence identity in Env but were characterized as either tier 1 (sensitive to neutralization), tier 2 (moderately resistant to neutralization), or tier 3 (resistant to neutralization). However, the introduction of premature stop codons in Env at position Q741/Q742 converted all three transfection-derived viruses to a tier 3-like phenotype, and these viruses were uniformly resistant to neutralization by sera from infected macaques and monoclonal antibodies (MAbs). These changes in neutralization sensitivity were not accompanied by an increase in either the virion Env content of infection-derived viruses or the infectivity of transfection-derived viruses in human cells, suggesting that CT mutations may result in global changes to the Env conformation. Our results demonstrate that some CT truncations can affect viral antigenicity and, as such, may not be suitable surrogate models of native HIV/SIV Env. IMPORTANCE Modifications to the SIV envelope protein (Env) are commonly used in structural and vaccine studies to stabilize and increase the expression of Env, often without consideration of effects on antigenicity. One such widespread modification is the truncation of the Env C-terminal tail. Here, we studied the effects of a particular cytoplasmic tail truncation in three SIVsm strains that have highly similar Env sequences but exhibit different sensitivities to neutralizing antibodies. After truncation of the Env CT, these viruses were all very resistant to neutralization by sera from infected macaques and monoclonal antibodies. The viruses with a truncated Env CT also did not exhibit the desired and typical increase in Env expression. These results underscore the importance of carefully evaluating the use of truncated Env as a model in HIV/SIV vaccine and imaging studies and of the continued need to find better models of native Env that contain fewer modifications.

Simian immunodeficiency virus (SIV) stocks for in vivo nonhuman primate models of AIDS are typically generated by transfection of 293T cells with molecularly cloned viral genomes or by expansion in productively infected T cells. Although titers of stocks are determined for infectivity in vitro prior to in vivo inoculation, virus production methods may differentially affect stock features that are not routinely analyzed but may impact in vivo infectivity, mucosal transmissibility, and early infection events. We performed a detailed analysis of nine SIV stocks, comprising five infection-derived SIVmac251 viral swarm stocks and paired infection- and transfected-293T-cell-derived stocks of both SIVmac239 and SIVmac766. Representative stocks were evaluated for (i) virus content, (ii) infectious titer, (iii) sequence diversity and polymorphism frequency by single-genome amplification and 454 pyrosequencing, (iv) virion-associated Env content, and (v) cytokine and chemokine content by 36-plex Luminex analysis. Regardless of production method, all stocks had comparable particle/infectivity ratios, with the transfected-293T stocks possessing the highest overall virus content and infectivity titers despite containing markedly lower levels of virion-associated Env than infection-derived viruses. Transfected-293T stocks also contained fewer and lower levels of cytokines and chemokines than infection-derived stocks, which had elevated levels of multiple analytes, with substantial variability among stocks. Sequencing of the infection-derived SIVmac251 stocks revealed variable levels of viral diversity between stocks, with evidence of stock-specific selection and expansion of unique viral lineages. These analyses suggest that there may be underappreciated features of SIV in vivo challenge stocks with the potential to impact early infection events, which may merit consideration when selecting virus stocks for in vivo studies.

The Ross operation is a complex procedure for aortic valve replacement in which the pulmonary autograft is replaced by a homograft. However, homograft availability is becoming limited. This report evaluates the performance of porcine stentless prostheses as alternative pulmonary substitutes. Echocardiographic results from two patient cohorts were compared at time of discharge and 1 year after a Ross procedure. Thirty-three patients (median age 42 years, range 17–62 years, 76% male) received a stentless prosthesis (median size 25.6 mm, range 25–29 mm) for right ventricular outflow tract reconstruction. Clinical data were not significantly different from 106 patients (median age 47 years, range 2–68 years, 75% male) who received cryopreserved homografts (median size 26 mm, range 20–33 mm). At time of discharge, peak pressure gradients (ΔPmax) across the stentless valve (median ΔPmax 13 mmHg, range 2–26 mmHg) were higher compared to homografts (median ΔPmax 7 mmHg, range 1–32 mmHg, p

Background: The excellent results of the Cox-Maze-III operation showed that a surgical treatment of atrial fibrillation is possible. The maze operation is surgically demanding and time-consuming. This fact led to the development of simplified modifications. Due to the good results of an exclusive left atrial maze procedure in combination with mitral valve surgery and new technologies of ablation, it seems reasonable to perform these techniques concomitant to cardiac surgery on a large number of patients.¶ Methods: From November 1999 until June 2000 a modified maze procedure concomitant to a cardiac surgical intervention was performed on 42 patients, with a mean age of 62.2 years, suffering from chronic or intermittent atrial fibrillation. Primary cardiac disease was mainly cardiac valve disease (mitral valve disease 19 patients, aortic valve disease 10 patients) or coronary heart disease (8 patients). After left atriotomy and with the use of the Thermaline probe (Boston Scientific, Corporation, San Jose, California, USA) a bilateral pulmonary veins isolation was carried out by radiofrequency ablation. An additional ablation line was directed from the left pulmonary veins to the posterior mitral valve anulus. Finally, the left atrial appendage was resected. An evaluation of the therapeutic success was carried out in the immediate postoperative course and 3 months after surgery, at that point of time operation-related influences on the refractory period of the atrial myocardium were negligible.¶ Results: At the time of discharge 32 patients (76.2%) showed a regular supraventricular rhythm. Twenty-one patients have already undergone the 3-month follow-up examination. At the time of discharge 13 out of these 21 patients (61.9%) were in sinus rhythm and at 3 months after surgery 18 out of these 21 patients (85.7%) showed a sinus rhythm with a restoration of atrial transport function echocardiographically determined. Three patients were still receiving antiarrhythmic medication.¶ Conclusion: The modified maze procedure in combination with cardiac surgical interventions proved to be easy, quick and reliable to perform. The early results suggest a high success rate of this technique. The long-term results have to be verified with further, regular follow-up examinations of the patients.

AIDS virus infections are rarely controlled by cell-mediated immunity, in part due to viral immune evasion and immunodeficiency resulting from CD4 + T-cell infection. One likely aspect of this failure is that antiviral cellular immune responses are either absent or present at low levels during the initial establishment of infection. To test whether an extensive, timely, and effective response could reduce the establishment of infection from a high-dose inoculum, we adoptively transferred large numbers of T cells that were molecularly engineered with anti-simian immunodeficiency virus (anti-SIV) activity into rhesus macaques 3 days following an intrarectal SIV inoculation. To measure in vivo antiviral activity, we assessed the number of viruses transmitted using SIVmac239X, a molecularly tagged viral stock containing 10 genotypic variants, at a dose calculated to transmit 12 founder viruses. Single-genome sequencing of plasma virus revealed that the two animals receiving T cells expressing SIV-specific T-cell receptors (TCRs) had significantly fewer viral genotypes than the two control animals receiving non-SIV-specific T cells (means of 4.0 versus 7.5 transmitted viral genotypes; P = 0.044). Accounting for the likelihood of transmission of multiple viruses of a particular genotype, the calculated means of the total number of founder viruses transmitted were 4.5 and 14.5 in the experimental and control groups, respectively ( P = 0.021). Thus, a large antiviral T-cell response timed with virus exposure can limit viral transmission. The presence of strong, preexisting T-cell responses, including those induced by vaccines, might help prevent the establishment of infection at the lower-exposure doses in humans that typically transmit only a single virus. IMPORTANCE The establishment of AIDS virus infection in an individual is essentially a race between the spreading virus and host immune defenses. Cell-mediated immune responses induced by infection or vaccination are important contributors in limiting viral replication. However, in human immunodeficiency virus (HIV)/SIV infection, the virus usually wins the race, irreversibly crippling the immune system before an effective cellular immune response is developed and active. We found that providing an accelerated response by adoptively transferring large numbers of antiviral T cells shortly after a high-dose mucosal inoculation, while not preventing infection altogether, limited the number of individual viruses transmitted. Thus, the presence of strong, preexisting T-cell responses, including those induced by vaccines, might prevent infection in humans, where the virus exposure is considerably lower.

We report the case of a 83-year-old man who had undergone a full root replacement with a stentless bioprosthesis 15 years earlier. He was now diagnosed with severe aortic valve regurgitation secondary to leaflet degeneration, moderate mitral regurgitation, and single-vessel coronary artery disease. To reduce cross-clamp time and technical difficulties a sutureless aortic prosthesis was used. His surgery and postoperative course were uneventful. This is the first report of the successful use of a sutureless aortic valve prosthesis in a patient after bioprosthetic full root replacement who required additional mitral repair and coronary artery bypass surgery.

We previously reported that human immunodeficiency virus type 1 (HIV-1) develops resistance to the cholesterol-binding compound amphotericin B methyl ester (AME) by acquiring mutations (P203L and S205L) in the cytoplasmic tail of the transmembrane envelope glycoprotein gp41 that create cleavage sites for the viral protease (PR). In the present study, we observed that a PR inhibitor-resistant (PIR) HIV-1 mutant is unable to efficiently cleave the gp41 cytoplasmic tail in P203L and S205L virions, resulting in loss of AME resistance. To define the pathway to AME resistance in the context of the PIR PR, we selected for resistance with an HIV-1 isolate expressing the mutant enzyme. We identified a new gp41 mutation, R236L, that results in cleavage of the gp41 tail by the PIR PR. These results highlight the central role of gp41 cleavage as the primary mechanism of AME resistance.

Starting in November 1999, we performed a left atrial radiofrequency ablation procedure concomitantly to a variety of cardiac surgical procedures. By January 2001, this ablation procedure had been performed on 100 patients (age 65.7 +/- 10.4 years, 53 % male, 47 % female, left atrium 51.0 +/- 7.5 mm) suffering either from chronic or paroxysmal atrial fibrillation. Primary cardiac pathology was mitral valve disease in most cases (43), aortic valve disease (28) or coronary heart disease (27). After bilateral pulmonary veins isolation, an additional ablation line was directed from the left pulmonary veins to the mitral valve annulus (Thermaline probe, Boston Scientific Corporation, USA). Finally, the left atrial appendage was resected. Surgical success was evaluated in the immediate postoperative course, 3 and 6 months postoperatively (ECG and echocardiography), and every year after that. Operative time was 229.7 +/- 56.5 min, ablation time 18.8 +/- 6.9 min. Follow-up is 95 % complete at the time of writing. Mean follow-up time was 7.3 months, ranging from 3 to 23 months. Success (sinus rhythm and atrial contraction) was proven in 72 out of 90 patients (80.0 %) (75.0 % mitral valve surgery, 84.0 % other cardiac surgery). The reported results support a broad spectrum of indications for this left atrial ablation procedure.

Dilatation of the pulmonary autograft is a major fear after the Ross procedure. We analyzed the results after reoperation for autograft dysfunction using a valve-sparing reimplantation technique (David procedure).From 1995 to 2012, 645 Ross operations were performed, with 630 (98%) of these as freestanding root replacements (mean follow-up, 8.3 ± 4.6 years). Forty-nine autograft reoperations occurred in 46 patients (0.89%/patient-year). Between 2005 and 2013, reoperation using a David procedure was performed in 18 of 35 patients (52%) with autograft dilatation at a mean interval of 11 ± 3.2 years after the Ross operation.The mean age of 18 patients receiving a David procedure as reoperation was 49.8 ± 13.9 years; 83% were male. The 30-day reoperative mortality was zero. The mean vascular graft size used for reimplantation was 29.5 ± 1.7 mm. At a mean follow-up time of 3.2 ± 2.3 years (100% complete), all patients (18 of 18) were alive and in New York Heart Association functional class I. One patient (5%) needed valve replacement for recurrent aortic regurgitation 2.6 years after the David procedure. In the remaining patients (95%), freedom from aortic regurgitation of grade 2 or greater was 100% at 3 years (regurgitation grade1, 14 of 17; 82%). Aortic valve gradients were clinically insignificant at 5.8 ± 2.1 mm Hg.Performing a David procedure was successful in the vast majority of patients with dilatation of the pulmonary autograft after a Ross operation and revealed good function of the preserved autograft at midterm follow-up. Reoperations could be performed with low perioperative morbidity and mortality.

Background In this report we address the question whether the Ross operation can be recommended in combined and complicated cardiac procedures. Methods From February 1995 to July 2000, we performed 203 Ross operations, 129 with ideal clinical presentation (group 1: mean age 41 +/- 13 years, male 105). In 74 patients, the clinical presentation was complex (group 2: mean age 35 +/- 17 years, male 57), defined as previous aortic or cardiac operations in 32, active endocarditis in 8 or combined procedures in 40 patients. Follow-up is 95 % complete. Results Neither early mortality nor thromboembolic events were observed. Complications in group 1 vs. group 2 were prolonged ventilation in 1 vs. 1, pacemaker insertion in 1 vs. 2, minor myocardial infarction in none vs. 2 and postoperative bleeds in 2 vs. 3 patients. In group 1, one patient died of hemoptysis at 25 months, and in group 2 one sudden death occurred at 5 months. In the long term, two patients required reoperation for autograft failure in group 1, and one on group 2. Pulmonary stenosis required surgical treatment in one patient of group 2. Echocardiography revealed physiological gradients across the autograft with no significant regurgitation in either group. Conclusion The Ross operation has excellent mid-term results and is a safe and attractive therapeutic approach, both in combined procedures and complex clinical presentations.

Background . The Ross operation approaches the ideal aortic valve replacement. Between February 1995 and February 2000 we performed 186 procedures. This article reviews modifications introduced reflecting our experience. Methods . In all patients the Ross operation was performed as root replacement. Echocardiographic follow-up was complete in 94% of patients. Results . No operative death or early mortality occurred, nor did thromboembolic or hemorrhagic events. One patient died at 25 months from hemoptysis with pulmonary valve vegetations. Three patients required reoperation for autograft insufficiency. In 1 patient a tethered cusp was repairable and in 2 patients progressive autograft dilatation required autograft replacement. After routinely incorporating support into the aortic annulus and replacing all dilated ascending aorta, autograft dilatation did not recur. For the pulmonary homograft, one outflow patch was placed to relieve a symptomatic gradient. Nine patients with elevated gradients were under observation. Echocardiography revealed autograft median peak systolic gradients of 4.6 ± 2.8 mm Hg, pulmonary homograft gradients of 14.8 ± 9.6 mm Hg, and nil or insignificant regurgitation. Conclusions . The aortic annulus must be supported and the dilated ascending aorta replaced. Root replacement with a short autograft allows consistent results. Pulmonary homograft dysfunction is rare but unpredictable.

BACKGROUND The pulmonary autograft approaches the ideal aortic valve substitute but numerous technical modifications are debated. The valves involved often differ in diameter and shape of the recipient annulus. We previously reported simplified surgical rules and early results of 52 patients and here we extend the report to 76 patients and analyze the mid-term results with respect to valve mismatch. METHODS We studied the influence of geometric discrepancies. Valve regurgitation and gradient are compared for size discrepancies up to or more than 3 mm between recipient annulus and pulmonary autograft. The normal tricuspid recipient aortic annulus is compared with the flat circular redo-prosthetic or bicuspid annulus. Patients with plication of the aortic annulus and remodeling of the distal aorta are reviewed, and lastly donor homograft to pulmonary autograft discrepancies up to and more than 3 mm are compared. RESULTS The results were comparable in all groups and no significant differences were observed. CONCLUSION The pulmonary autograft operation may be simplified, with good results at the least in the first year despite operative tailoring due to valve discrepancies.

Interleukin-15 (IL-15), a 114 amino acid cytokine related to IL-2, regulates immune homeostasis and the fate of many lymphocyte subsets. We reported that IL-15 is present as a heterodimer associated with soluble IL-15 Receptor alpha (sIL-15Ra) in the blood of mice and humans. Here, we show efficient production of this non-covalently linked but stable heterodimer in clonal human HEK293 cells and release of the processed IL-15/sIL-15Rα heterodimer in the medium. Purification of the IL-15 and sIL-15Rα polypeptides allowed identification of the proteolytic cleavage site of IL-15Rα and characterization of multiple glycosylation sites. Administration of purified, reconstituted IL-15/sIL-15Rα heterodimer resulted in sustained plasma levels and in robust expansion of NK and T cells in mice, demonstrating pharmacokinetics and in vivo bioactivity superior to E. coli derived single-chain IL-15. The identified properties of heterodimeric IL-15 provide a strong rationale for the evaluation of this molecule for clinical applications.

Background The enthusiasm about the advantages of a viable autologous transplant faded with recent reports of autograft deterioration and associated reoperations after the Ross procedure. This report evaluates predictors for autograft failure and outcomes extending into the second decade after a Ross procedure. Methods From 1995 through 2012, 645 consecutive patients (mean age, 42.3 ± 14.2 years; 76% males) underwent a Ross operation using mainly the root replacement technique (98%). They were prospectively followed up with clinical and echocardiographic evaluations. Total follow-up was 5,349 patient-years and was 96% complete. Mean follow-up duration was 8.4 ± 4.6 years (range, 0 to 17.4 years). Results Early mortality was 0.9% (n = 6). Cumulative survival at 15 years was 92.7% (95% confidence interval, 90.1% to 95.3%) and did not differ from the general German population ( p = 0.261). Freedom from reoperation on the autograft or the pulmonary allograft at 12 years was 91.6% (95% confidence interval, 88.5% to 94.9%) and 95.0% (95% confidence interval, 92.8% to 97.2%), respectively. Sixty-five patients (10.1%) required a total of 78 valve-related reoperations after a Ross procedure (1.5%/patient-year) with a reoperative hospital mortality of 3.8% (n = 3). Forty-seven autograft reoperations were observed in 44 patients (0.87%/patient-year); 22 of them (47%) could be performed as a valve-sparing procedure. Preoperative aortic valve regurgitation and an aortic annulus of at least 26 mm were identified as predictors for autograft failure. Conclusions In this large series, the Ross procedure resulted in excellent long-term survival rates with a low risk of valve-related morbidity and a considerably low rate of reoperations in young and middle-aged patients and should be considered as an important treatment option in this cohort.

Although xenotropic murine leukemia virus-related virus (XMRV) has been previously linked to prostate cancer and myalgic encephalomyelitis/chronic fatigue syndrome, recent data indicate that results interpreted as evidence of human XMRV infection reflect laboratory contamination rather than authentic in vivo infection. Nevertheless, XMRV is a retrovirus of undefined pathogenic potential that is able to replicate in human cells. Here we describe a comprehensive analysis of two male pigtailed macaques ( Macaca nemestrina ) experimentally infected with XMRV. Following intravenous inoculation with >10 10 RNA copy equivalents of XMRV, viral replication was limited and transient, peaking at ≤2,200 viral RNA (vRNA) copies/ml plasma and becoming undetectable by 4 weeks postinfection, though viral DNA (vDNA) in peripheral blood mononuclear cells remained detectable through 119 days of follow-up. Similarly, vRNA was not detectable in lymph nodes by in situ hybridization despite detectable vDNA. Sequencing of cell-associated vDNA revealed extensive G-to-A hypermutation, suggestive of APOBEC-mediated viral restriction. Consistent with limited viral replication, we found transient upregulation of type I interferon responses that returned to baseline by 2 weeks postinfection, no detectable cellular immune responses, and limited or no spread to prostate tissue. Antibody responses, including neutralizing antibodies, however, were detectable by 2 weeks postinfection and maintained throughout the study. Both animals were healthy for the duration of follow-up. These findings indicate that XMRV replication and spread were limited in pigtailed macaques, predominantly by APOBEC-mediated hypermutation. Given that human APOBEC proteins restrict XMRV infection in vitro , human XMRV infection, if it occurred, would be expected to be characterized by similarly limited viral replication and spread.

Grimmia antarctici is abundant on the Bailey and Clark Peninsulas, Wilkes Land, East Antarctica. It grows as a turf in wet locations and as cushions at relatively dry sites. This paper documents substantial differences in the internal CO2 concentration of cushion and turf communities during the growing season. In November, CO2 levels in the rhizo/phylloplane of both growth forms were close to ambient (around 350 ppm). Over the next two months the levels increased tenfold in turf but remained essentially constant in cushions. This means that the actively growing shoot tips of turf would be photosynthesizing at optimal CO2 concentration (i.e. close to CO2 saturation) for most of the summer. Photosynthesis in cushions, on the other hand, would be severely limited by CO2. These findings may account for the observations of Kappen et al. (1989), made at the same field sites in January 1986, that turf photosynthesizes at higher rates than cushions under simulated field conditions and is more resistant t...

Background Although the Ross operation requires double-valve replacement for aortic valve pathology, it is the only autologous, aortic valve replacement available. We report a single-unit's 11-year experience. Methods Before August 2006, 467 patients (mean age, 41 ± 15 years; 358 males) underwent a Ross operation. The right ventricular outflow tract was repaired with a cryopreserved pulmonary homograft. Follow-up was 94.4% complete. Results The 30-day mortality was 0.6%. The Kaplan-Meier survival estimate at 120 months was 94.4% ± 2.9% (standard error [SE], 0.0146). Reoperation was due to autograft failure in 15 patients (7 repairs, 8 replacements), with a Kaplan-Meier freedom from autograft failure measured as reoperation or regurgitation exceeding grade II at 120 months of 94.2% ± 2.8% (SE, 0.0142). Homograft replacement, mostly due to stenosis, occurred in 11 patients. Freedom from homograft dysfunction, defined as homograft reoperation or peak homograft gradient of 30 mm Hg or more, at 120 months was 79.3% ± 7.3% (SE, 0.0372). Freedom from all autograft- and homograft-related reoperations at 120 months was 85.9% ± 6.3% (SE, 0.0321). Autograft or homograft endocarditis occurred in 8 patients, and 1 patient had simultaneous endocarditis of both valves. Conclusions Patient survival and freedom from prostheses-related events over 11 years still compares favorably with conventional heart valve prostheses. Mortality and morbidity remain low. Reoperation for autograft or homograft failure is higher than our previous reports, and endocarditis is also evident, 1.9% (9 of 467). Homograft dysfunction is higher in younger recipients.

HIV-1 virions are highly enriched in cholesterol relative to the cellular plasma membrane. We recently reported that a cholesterol-binding compound, amphotericin B methyl ester (AME), blocks HIV-1 entry and that single amino acid substitutions in the cytoplasmic tail of the transmembrane envelope glycoprotein gp41 confer resistance to AME. In this study, we defined the mechanism of resistance to AME. We observed that the gp41 in AME-resistant virions is substantially smaller than wild-type gp41. Remarkably, we found that this shift in gp41 size is due to cleavage of the gp41 cytoplasmic tail by the viral protease. We mapped the protease-mediated cleavage to two sites in the cytoplasmic tail and showed that gp41 truncations in this region also confer AME resistance. Thus, to escape the inhibitory effects of AME, HIV-1 evolved a mechanism of protease-mediated envelope glycoprotein cleavage used by several other retroviruses to activate envelope glycoprotein fusogenicity. In contrast to the mechanism of AME resistance observed for HIV-1, we demonstrate that simian immunodeficiency virus can escape from AME via the introduction of premature termination codons in the gp41 cytoplasmic tail coding region. These findings demonstrate that in human T cell lines, HIV-1 and simian immunodeficiency virus can evolve distinct strategies for evading AME, reflecting their differential requirements for the gp41 cytoplasmic tail in virus replication. These data reveal that HIV-1 can escape from an inhibitor of viral entry by acquiring mutations that cause the cytoplasmic tail of gp41 to be cleaved by the viral protease.

Human immunodeficiency virus type 1 (HIV-1) infects CD4 + T lymphocytes and monocytes/macrophages, incorporating host proteins in the process of assembly and budding. Analysis of the host cell proteins incorporated into virions can provide insights into viral biology. We characterized proteins in highly purified HIV-1 virions produced from human monocyte-derived macrophages (MDM), within which virus buds predominantly into intracytoplasmic vesicles, in contrast to the plasmalemmal budding of HIV-1 typically seen with infected T cells. Liquid chromatography-linked tandem mass spectrometry of highly purified virions identified many cellular proteins, including 33 previously described proteins in HIV-1 preparations from other cell types. Proteins involved in many different cellular structures and functions were present, including those from the cytoskeleton, adhesion, signaling, intracellular trafficking, chaperone, metabolic, ubiquitin/proteasomal, and immune response systems. We also identified annexins, annexin-binding proteins, Rab proteins, and other proteins involved in membrane organization, vesicular trafficking, and late endosomal function, as well as apolipoprotein E, which participates in cholesterol transport, immunoregulation, and modulation of cell growth and differentiation. Several tetraspanins, markers of the late endosomal compartment, were also identified. MDM-derived HIV contained 26 of 37 proteins previously found in exosomes, consistent with the idea that HIV uses the late endosome/multivesicular body pathway during virion budding from macrophages.

Background The Ross operation is increasingly accepted as an alternative to conventional valve prostheses for children, adolescents, and young adults. We review patients younger than 20 years of age. Methods Of 404 Ross operations done before November 2004, 60 were young patients with a median age of 12 years (range, 1 to 20 years). The pulmonary autograft technique universally was as a free root. A cryopreserved pulmonary homograft reconstructed the right ventricular outflow tract. Results Early postoperative complications were reentry for bleeding in 2 patients and one pacemaker insertion. No thromboembolic or hemorrhagic events occurred during the follow-up of 42 ± 27 months. Two late deaths occurred, one from myocardial infarction after 3 months and another sudden death after 5 years, probably from critical pulmonary homograft stenosis. Echocardiographic follow-up revealed a median peak gradient of 6.3 ± 3 mm Hg across the autograft. The median pulmonary homograft peak gradient of 19.1 ± 13.7 mm Hg was increased to more than 30 mm Hg in 6 patients. Another 6 patients had moderate but clinically insignificant pulmonary homograft regurgitation. Altogether, 6 patients required reoperation for replacement of stenotic homografts. No autograft related reoperation occurred. Conclusions Young patients with the Ross operation had good mid-term autograft function and no perioperative mortality. Factors that justify the choice of the Ross operation for young patients are the normal physiologic hemodynamics and growth of the autograft as well as freedom from anticoagulation. A 10% reoperation rate, elevated pulmonary homograft gradients, and the surgical complexity remain limiting factors.

The zinc finger motifs in retroviral nucleocapsid (NC) proteins are essential for viral replication. Disruption of these Cys-X 2 -Cys-X 4 -His-X 4 -Cys zinc-binding structures eliminates infectivity. To determine if N -ethylmaleimide (NEM) can inactivate human immunodeficiency virus type 1 (HIV-1) or simian immunodeficiency virus (SIV) preparations by alkylating cysteines of NC zinc fingers, we treated infectious virus with NEM and evaluated inactivation of infectivity in cell-based assays. Inactivation was rapid and proportional to the NEM concentration. NEM treatment of HIV-1 or SIV resulted in extensive covalent modification of NC and other internal virion proteins. In contrast, viral envelope glycoproteins, in which the cysteines are disulfide bonded, remained intact and functional, as assayed by high-performance liquid chromatography, fusion-from-without analyses, and dendritic cell capture. Quantitative PCR assays for reverse transcription intermediates showed that NEM and 2,2′-dipyridyl disulfide (aldrithiol-2), a reagent which inactivates retroviruses through oxidation of cysteines in internal virion proteins such as NC, blocked HIV-1 reverse transcription prior to the formation of minus-strand strong-stop products. However, the reverse transcriptase from NEM-treated virions remained active in exogenous template assays, consistent with a role for NC in reverse transcription. Since disruption of NC zinc finger structures by NEM blocks early postentry steps in the retroviral infection cycle, virus preparations with modified NC proteins may be useful as vaccine immunogens and probes of the role of NC in viral replication.

We report the case of a 73-year-old patient with severe ischemic mitral regurgitation (MR). She subsequently underwent combined coronary artery revascularization and mitral valve annuloplasty using the adjustable enCorSQ device (MiCardia Corporation, Irvine, CA). Three months later she experienced recurrent symptomatic severe MR. Accessing the subcutaneous lead, activation and downsizing of the device within 45 seconds resulted in trace MR. The result was unchanged 1 month later.

The pulmonary autograft operation has achieved broad acceptance and may be the ideal aortic valve substitute. Both the pulmonary autograft and the aortic homograft are more complicated procedures than prosthetic valve replacement. The trend to insert the pulmonary autograft as a root replacement rather than in the subcoronary position has achieved greater uniformity in the results, but there is still confusing diversity in opinions on technical details and anatomical dimensions. The importance of both size and shape mismatches between the three valves involved has received little attention. The valves often differ in diameter and in the shape of the recipient aortic annulus. This uncertainty and the diversity of opinions on essential technical details was disconcerting when we proceeded from aortic homograft-to-pulmonary autograft operations, this was compounded by only a single homograft being available for every operation as we have no homograft bank.We compared the hemodynamic results regarding various geometric mismatches. All operative details were the same and patients were studied at regular intervals. Comparisons were made in patients with mismatch between recipient aortic annulus and pulmonary autograft. Patients with a normal tricuspid aortic annulus were compared to those with either a circular redo prosthetic valve annulus or a bicuspid recipient annulus. Thirdly we compared the patients with plication of the aortic annulus to those with remodeling of the distal aorta. Lastly we compared mismatch between donor homograft and pulmonary autograft.No influence of geometric mismatch between the three valves could be found on the results of the pulmonary autograft operation.Good results are obtainable without a painful learning curve if one keeps to certain surgical principles. It need not be a complicated operation and geometric mismatches between the three valves involved may be compensated for adequately.

' Plotless ' techniques for determining population densities have been developed for, and applied to, higher plant populations. They can often be carried out more rapidly than techniques involving total counts of individuals in plots, or quadrants, but such plotless techniques have not been generally applied to the estimation of densities of bacterial cells. Direct microscopical counting of cell numbers in a field of view, an example of a plot-related method, has been traditionally used for microbial cell counts. In this study 'plot' and ' plotless ' methods on a variety of bacterial samples are compared. Estimates of bacterial cell density were obtained by measuring the distance of cells from a fixed point in a field of view. The values, which were more rapidly obtained, were directly correlated with total cell counts. Although there was some apparent deviation from a perfect 1:1 relationship with total counts, as indicated by a correlation coefficient less than 1.0, there were no significant differences between the replicated counts of bacteria on samples of tissue from the surface of Hypholoma basidiocarps (P less than 0.05). This indicated that the methods of enumeration were comparable. The distance-related estimates could readily be obtained from fields of view with cell densities varying over several orders of magnitude. It was more rapidly applied, particularly at high density, and the method was applicable not only to random cell distributions but also to the non-random distributions encountered when microbial cells aggregated into microcolonies. The method appears to be particularly well-suited for automated, digitized, direct counting procedures, as well as to estimating bacterial numbers on membrane filters and natural substrates.

Der Entschleunigungstest zeichnet sich durch zwei nystaktische Reaktionen mit entgegengesetzter Schlagrichtung aus. Eine Analyse des Erregungsvorganges und der Vergleich mehrerer Untersuchungsarten (Entschleunigungstest, Langdrehmethode, einfache Verzogerungsteste, unterbrochener Entschleunigungstest) zeigt, das sowohl antagonistische wie synergistische Interferenzen eine Rolle spielen. Die antagonistische Interferenz ist auf Grund der Endolymphverschiebung berechenbar, die II. (inversen) Phasen, die beim Zustandekommen der 2. Reaktion mitwirken, sind nicht berechenbar. An Hand von Fallen vestibularer Storung werden die Schwierigkeiten der Deutung des Entschleunigungstestes aufgezeigt.

A host cytidine deaminase, APOBEC3G (A3G), inhibits replication of human immunodeficiency virus type 1 (HIV-1) by incorporating into virions in the absence of the virally encoded Vif protein (Deltavif virions), at least in part by causing G-to-A hypermutation. To gain insight into the antiretroviral function of A3G, we determined the quantities of A3G molecules that are incorporated in Deltavif virions. We combined three experimental approaches-reversed-phase high-pressure liquid chromatography (HPLC), scintillation proximity assay (SPA), and quantitative immunoblotting-to determine the molar ratio of A3G to HIV-1 capsid protein in Deltavif virions. Our studies revealed that the amount of the A3G incorporated into Deltavif virions was proportional to the level of its expression in the viral producing cells, and the ratio of the A3G to Gag in the Deltavif virions produced from activated human peripheral blood mononuclear cells (PBMC) was approximately 1:439. Based on previous estimates of the stoichiometry of HIV-1 Gag in virions (1400-5000), we conclude that approximately 7 (+/-4) molecules of A3G are incorporated into Deltavif virions produced from human PBMCs. These results indicate that virion incorporation of only a few molecules of A3G is sufficient to inhibit HIV-1 replication.

Recombinant lentiviral vectors pseudotyped with heterologous HIV-1 envelope glycoproteins allow rapid and accurate measurement of antibody-mediated HIV-1 neutralization. However, the neutralization phenotypes of envelope pseudoviruses have not been directly compared to isogenic replication competent HIV-1. We produced pseudoviruses expressing three different HIV-1 envelope glycoproteins and subcloned the same three env genes into a replication competent NL4-3 molecular clone. For each of the antibodies tested, the neutralization dose–response curves of pseudoviruses and corresponding replication competent viruses were similar. Thus, envelope pseudoviruses can be used to study the anti-HIV-1 neutralizing antibody response. A single passage of replication competent virus derived from 293T cells through peripheral blood mononuclear cells (PBMC) caused a substantial decrease in sensitivity to neutralizing antibodies. This was associated with an increase in average virion envelope glycoprotein content of the PBMC-derived virus. Replication competent HIV-1 and isogenic envelope pseudoviruses have similar neutralization characteristics, but passage into PBMC is associated with decreased sensitivity to neutralization.