Metabolic constraints on the body size scaling of extreme population densities

Pest outbreaks, harmful algal blooms and population collapses are extreme events with critical consequences for ecosystems. Therefore, understanding the ecological mechanisms underlying these extreme events is crucial. We evaluated theoretical predictions on the size scaling and variance of extreme population abundance by combining (i) the generalized extreme value (GEV) theory and (ii) the resource-limited metabolic restriction hypothesis for population abundance. Using the phytoplankton data from the L4 station in the English Channel, we showed a negative size scaling of the expected value of maximal density, whose confidence interval included the predicted metabolic scaling (α = -1) supporting theoretical predictions. The role of resources and temperature in the distribution of the size-abundance pattern and residuals was well characterized by the GEV distribution. This comprehensive modelling framework will allow to elucidate community structure and fluctuations and provide unbiased return times estimates, thereby improving the prediction accuracy of the timing of the population outbreaks.

Rare delayed cardiac tamponade in a pig after cardiac surgery

Objective

Delayed cardiac tamponade, a life‐threatening complication of pericardial effusion in humans, has rarely been described in large animal models. We report here a pig with cardiac tamponade that developed 29 days after cardiac surgery.

Study Design

Case report.

Animals

One 45‐kg domestic pig.

Methods

Open‐chest surgery was performed on a pig to induce chronic heart failure. At 15 days after surgery, the pig's breathing appeared laboured; induced heart failure was considered the cause. Routine heart failure medications were administered.

Results

On day 28, the pig's status deteriorated. On day 29, echocardiography performed just before the pig's death showed a large pericardial effusion, mainly in the lateral and anterior walls of the right heart, with several fibre exudation bands. The right heart was severely compressed with an extremely small right ventricle. An emergency sternotomy was unsuccessful. Pathologic examination showed a severely thickened, fibrous pericardium. The pericardial sac was distended (up to 4.5 cm) and was full of dark brown, soft, friable material. Epicardial haemorrhage with a fresh, organised thrombus was noted in the pericardium.

Conclusion

Delayed tamponade occurring at least 15 days after open‐chest surgery is easy to misdiagnose or overlook in large animal models where attention is often focused on primary pathological model changes. To decrease mortality in animal models, researchers should be aware of potential complications and use the same level of follow‐up monitoring of large animals as in clinical care.

Victor J. Ferrans, MD, PhD (1937-2001)

NA

Contribution of Increased Expression of Yin Yang 2 to Development of Cardiomyopathy

Yin Yang 2 (YY2) is a member of the Yin Yang family of transcription factors. Although the bioactivity of YY2 has been previously studied, its role in cardiovascular diseases is not known. We observed the increased expression of YY2 in failing human hearts compared with control hearts, raising the question of whether YY2 is involved in the pathogenesis of cardiomyopathy. To investigate the potential contribution of YY2 to the development of cardiomyopathy, we crossed two independent transgenic (Tg) mouse lines, pCAG-YY2-Tg+and alpha-myosin heavy chain-cre (α-MHC-Cre), to generate two independent double transgenic (dTg) mouse lines in which the conditional cardiomyocyte-specific expression of YY2 driven by the α-MHC promoter was mediated by Cre recombinase, starting at embryonic day 9.0. In dTg mice, we observed partial embryonic lethality and hearts with defective cardiomyocyte proliferation. Surviving dTg mice from both lines developed cardiomyopathy and heart failure that occurred with aging, showing different degrees of severity that were associated with the level of transgene expression. The development of cardiomyopathy was accompanied by increased levels of cardiac disease markers, apoptosis, and cardiac fibrosis. Our studies further revealed that the Cre-mediated cardiomyocyte-specific increase in YY2 expression led to increased levels of Beclin 1 and LC3II, indicating that YY2 is involved in mediating autophagic activity in mouse hearts in vivo. Also, compared with control hearts, dTg mouse hearts showed increased JNK activity. Because autophagy and JNK activity are important for maintaining cardiac homeostasis, the dysregulation of these signaling pathways may contribute to YY2-induced cardiomyopathy and heart failure in vivo.

Clinicopathological manifestations of myocarditis in a heart failure population

Myocarditis continues to present challenges in diagnosis and management. The goal of this study is to determine the occurrence and manifestations of myocarditis in a heart failure (HF) population. The analyzed patients had acute or persistent HF and were referred over a 6-year period to a quaternary HF center for advanced HF therapies including mechanical circulatory support, left ventricular assist device (LVAD) implantation, and/or heart transplantation. The histopathological diagnosis of myocarditis was made based on the presence of an inflammatory infiltrate of the myocardium, typically with associated cardiomyocyte (CMC) damage, combined as indicated with immunohistochemical and molecular biology characterization. The pathological findings were correlated with a panel of clinical parameters and clinical course of the patients. Myocarditis was identified in 36 patients, with initial diagnoses made in 10 (40%) of 25 by endomyocardial biopsy (EMB), 1 by atrial biopsy (maze procedure), 7 (2.1%) of 331 at LVAD implantation, and 18 (7.8%) of 229 in the explanted heart. There were 20 cases of lymphocytic myocarditis, 4 cases of giant cell myocarditis, 3 cases of eosinophilic myocarditis, and 9 cases of lymphohistocytic with granulomas myocarditis - cardiac sarcoidosis. EMB was performed in 25 patients and was positive in 10 (40%) of cases. Myocarditis was found in 23 explanted hearts including 18 cases de novo and 5 cases with a previously positive specimen. Of the 23 explanted hearts, 21 were nonischemic cardiomyopathy and 2 were ischemic cardiomyopathy. Our findings show that, in patients presenting to a quaternary medical center, myocarditis can be manifest as acute HF as well as a complicating factor in chronic HF.

Community fluctuations and local extinction in a planktonic food web

Determining statistical patterns irrespective of interacting agents (i.e. macroecology) is useful to explore the mechanisms driving population fluctuations and extinctions in natural food webs. Here, we tested four predictions of a neutral model on the distribution of community fluctuations (CF) and the distributions of persistence times (APT). Novel predictions for the food web were generated by combining (1) body size-density scaling, (2) Taylor's law and (3) low efficiency of trophic transference. Predictions were evaluated on an exceptional data set of plankton with 15 years of weekly samples encompassing c. 250 planktonic species from three trophic levels, sampled in the western English Channel. Highly symmetric non-Gaussian distributions of CF support zero-sum dynamics. Variability in CF decreased while a change from an exponential to a power law distribution of APT from basal to upper trophic positions was detected. Results suggest a predictable but profound effect of trophic position on fluctuations and extinction in natural communities.

The invariance of production per unit of food consumed in fish populations

The amount of biomass production per unit of food consumed (P/Q) represents an important quantity in ecosystem functioning, because it indicates how efficient a population transforms ingested food into biomass. Several investigations have noticed that P/Q remains relatively constant (or invariant) across fish population that feed at the same food-type level (carnivorous/herbivorous). Nevertheless, theoretical explanation for this invariant is still lacking. In this paper, we demonstrate that P/Q remains invariant across fish populations with stable-age distribution. Three key assumptions underpin the P/Q invariant: (1) the ratio between natural mortality M and von Bertalanffy growth parameter k (M/k ratio) should remain invariant across fish populations; (2) a parameter defining the fraction of ingested food available for growth needs to remain constant across fish that feed at the same trophic level; (3) third, the ratio between length at age 0 ([Formula: see text]) and asymptotic length ([Formula: see text]) should be constant across fish populations. The influence of these assumptions on the P/Q estimates were numerically assessed considering fish populations of different lifespan. Numerical evaluations show that the most critical condition highly relates to the first assumption, M/k. Results are discussed in the context of the reliability of the required assumption to consider the P/Q invariant in stable-age distributed fish populations.

Comparative Efficacy of Nebivolol and Metoprolol to Prevent Tachycardia-Induced Cardiomyopathy in a Porcine Model

Chronic tachycardia is a well-known cause of nonischemic cardiomyopathy. We hypothesized that nebivolol, a β-blocker with nitric oxide activity, would be superior to a pure β-blocker in preventing tachycardia-induced cardiomyopathy in a porcine model. Fifteen healthy Yucatan pigs were randomly assigned to receive nebivolol, metoprolol, or placebo once a day. All pigs underwent dual-chamber pacemaker implantation. The medication was started the day after the pacemaker implantation. On day 7 after implantation, each pacemaker was set at atrioventricular pace (rate, 170 beats/min), and the pigs were observed for another 7 weeks. Transthoracic echocardiograms, serum catecholamine levels, and blood chemistry data were obtained at baseline and at the end of the study. At the end of week 8, the pigs were euthanized, and complete histopathologic studies were performed. All the pigs developed left ventricular cardiomyopathy but remained hemodynamically stable and survived to the end of the study. The mean left ventricular ejection fraction decreased from baseline by 34%, 20%, and 20% in the nebivolol, metoprolol, and placebo groups, respectively. These changes did not differ significantly among the 3 groups (P =0.51). Histopathologic analysis revealed mild left ventricular perivascular fibrosis with cardiomyocyte hypertrophy in 14 of the 15 pigs. Both nebivolol and metoprolol failed to prevent cardiomyopathy in our animal model of persistent tachycardia and a high catecholamine state.

Left ventricular noncompaction cardiomyopathy in end-stage heart failure patients undergoing orthotopic heart transplantation

BACKGROUND

Previous studies reported that left ventricular noncompaction (LVNC) is a cardiomyopathy, familial or sporadic, arising from arrest of the normal process of trabecular remodeling during embryonic development. The diagnosis is usually made by echocardiography, but to date, there has been little research on the occurrence and clinicopathological features of LVNC in the explanted hearts of orthotopic heart transplant (OHT) recipients.

DESIGN

The clinical, echocardiographic, and pathologic findings were reviewed for evidence of LVNC, diagnosed by echocardiographic criteria, in 105 patients with end-stage heart failure (HF) undergoing OHT. Analyses of multiple sections of the explanted hearts were carried out. The hearts were evaluated for grades (0, negative; 1, mild/occasional foci; 2, moderate/multiple foci; 3, severe/extensive, diffuse) of fibrosis, reactive and replacement, hypertrophy, myocytolysis in left ventricle, right ventricle, interventricular septum, and atria. Absolute measurements of noncompacted and compacted portions of the left ventricle wall and noncompacted/compacted ratios were calculated.

RESULTS

Isolated LVNC was observed in 0 of 54 ischemic cardiomyopathy and in 4 of 51 (7.8%) nonischemic cardiomyopathy patients - 2 men and 2 women, with a mean age±SEM of 34.2±6.9years. The echocardiogram disclosed marked left ventricular dilatation, prominent trabeculations, and left ventricle ejection fraction <20%. Mural thrombi were seen in 3 of 4 (75%) patients. The heart weight mean±SEM was 468±55.3 g (range, 340-600g); noncompacted myocardium was 22±5.8mm, compacted myocardium was 13.2±3.5mm, and noncompacted/compacted ratio was 1.7/1±0.2. The total scores of hypetrophy, myocytolysis, and fibrosis were as follows: left ventricle, 7.7±0.2; right ventricle, 6.2±0.5; interventricular septum, 6.7±0.2; and atria, 7.5±0.3.

CONCLUSIONS

LVNC is an unusual form of nonischemic cardiomyopathy in patients suffering from end-stage HF undergoing OHT. The variability in the noncompacted/compacted ratio and discordance between the echocardiographic and pathological findings points to the need for further clarification of diagnostic imaging and diagnostic criteria for LVNC. Further studies in larger series, correlating the anatomoclinical and genetic variables, also would improve our understanding of LVNC as a cause of advanced HF leading to OHT.

Involvement of activated SUMO-2 conjugation in cardiomyopathy

Sumoylation is a posttranslational modification that regulates a wide spectrum of cellular activities. Cardiomyopathy is the leading cause of heart failure. Whether sumoylation, particularly SUMO-2/3 conjugation, is involved in cardiomyopathy has not been investigated. We report here that SUMO-2/3 conjugation was elevated in the human failing hearts, and we investigated the impact of increased SUMO-2 conjugation on heart function by using the gain-of-function approach in mice, in which cardiac specific expression of constitutively active SUMO-2 was governed by alpha myosin heavy chain promoter (MHC-SUMO-2 transgenic, SUMO-2-Tg). Four of five independent SUMO-2-Tg mouse lines exhibited cardiomyopathy with various severities, ranging from acute heart failure leading to early death to the development of chronic cardiomyopathy with aging. We further revealed that SUMO-2 directly regulated apoptotic process by at least partially targeting calpain 2 and its natural inhibitor calpastatin. SUMO conjugation to calpain 2 promoted its enzymatic activity, and SUMO attachment to calpastatin mainly promoted its turnover and altered its subcellular distribution. Thus, enhanced SUMO-2 conjugation led to increased apoptosis and played a pathogenic role in the development of cardiomyopathy and heart failure.

Anthracycline treatment and ventricular remodeling in left ventricular assist device patients

Nonischemic cardiomyopathy can complicate antineoplastic therapy and lead to irreversible heart failure. We evaluated structural changes at the time of left ventricular assist device implantation in heart failure patients who had been exposed to anthracycline, and we correlated those changes with clinical presentation. We retrospectively studied left ventricular core samples taken at implantation of the HeartMate II left ventricular assist device in 12 heart failure patients (mean age, 46 ± 16 yr) who had histories of anthracycline exposure. We evaluated those samples for hypertrophy, myocytolysis, and fibrosis. Histopathologic findings showed moderate-to-severe myocyte hypertrophy, moderate myocytolysis, and perivascular and interstitial fibrosis with areas of replacement fibrosis. Ultrastructural studies revealed marked decreases in myofibrils, diffuse mitochondrial swelling, and disorganization of the sarcoplasmic reticulum. The interval between anthracycline therapy and heart failure was a mean of 6.8 ± 5.7 years; duration of heart failure symptoms, 38 ± 47 months; and duration of device support, 414 ± 266 days. Four patients are continuing on device support, 3 have undergone transplantation, 3 have undergone device explantation, and 2 have died. The time of heart failure onset and the duration of symptoms did not correlate with the severity and extent of the histopathologic changes. The histopathologic findings and the clinical course varied in heart failure patients with anthracycline exposure. No correlation was observed between anthracycline therapy and the development or duration of heart failure symptoms, severity of histopathologic changes, or outcomes.

Fibrosis and heart failure

The extracellular matrix (ECM) is a living network of proteins that maintains the structural integrity of the myocardium and allows the transmission of electrical and mechanical forces between the myocytes for systole and diastole. During ventricular remodeling, as a result of iterations in the hemodynamic workload, collagen, the main component of the ECM, increases and occupies the areas between the myocytes and the vessels. The resultant fibrosis (reparative fibrosis) is initially a compensatory mechanism and may progress adversely influencing tissue stiffness and ventricular function. Replacement fibrosis appears at sites of previous cardiomyocyte necrosis to preserve the structural integrity of the myocardium, but with the subsequent formation of scar tissue and widespread distribution, it has adverse functional consequences. Continued accumulation of collagen impairs diastolic function and compromises systolic mechanics. Nevertheless, the development of fibrosis is a dynamic process wherein myofibroblasts, the principal cellular elements of fibrosis, are not only metabolically active and capable of the production and upregulation of cytokines but also have contractile properties. During the process of reverse remodeling with left ventricular assist device unloading, cellular, structural, and functional improvements are observed in terminal heart failure patients. With the advent of anti-fibrotic pharmacologic therapies, cellular therapy, and ventricular support devices, fibrosis has become an important therapeutic target in heart failure patients. Herein, we review the current concepts of fibrosis as a main component of ventricular remodeling in heart failure patients. Our aim is to integrate the histopathologic process of fibrosis with the neurohormonal, cytochemical, and molecular changes that lead to ventricular remodeling and its physiologic consequences in patients. The concept of fibrosis as living scar allows us to envision targeting this scar as a means of improving ventricular function in heart failure patients.

Ventricular reconditioning and pump explantation in patients supported by continuous-flow left ventricular assist devices

BACKGROUND

The potential for myocardial reconditioning and device explantation after long-term continuous-flow left ventricular assist device (LVAD) support presents an opportunity to delay or avoid transplantation in select patients.

METHODS

Thirty of 657 patients with end-stage heart failure supported with continuous-flow LVADs were assessed for device explantation. Each patient underwent an individualized process of weaning focused on principles of ventricular unloading, gradual reconditioning, and transition to medical therapy.

RESULTS

After varying reconditioning periods, 27 patients (16 men, 11 women; age, 39 ± 12 years) underwent LVAD explant, and 3 patients (2 men, 1 woman; age, 22 ± 6 years) were evaluated for explantation but could not be weaned. The duration of LVAD support was 533 ± 424 days (range, 42-1,937 days) for the explant cohort and 1,097 ± 424 days (range, 643-1,483) for the non-explant cohort. The LV end-diastolic dimension, LV ejection fraction, systolic pulmonary artery pressure, cardiac output, and cardiac index in the explant cohort were significantly improved at explantation (all, p < 0.05). Two late deaths occurred after LVAD explantation despite satisfactory native cardiac function, and 1 patient required resumption of LVAD support 2.7 years after device removal. The remaining explant patients remain in New York Heart Association classes I to II with medical management alone (mean survival post-explant, 1,172 ± 948 days). The 3 candidates who could not be weaned ultimately underwent transplantation.

CONCLUSIONS

The potential for recovery of native LV function after long-term continuous-flow LVAD support should encourage a more aggressive approach to ventricular reconditioning with the goal of device explantation and a return to medical management, particularly in young patients with dilated cardiomyopathy.

SENP5, a SUMO isopeptidase, induces apoptosis and cardiomyopathy

Cardiomyopathy presents a major health issue and is a leading cause of heart failure. Although a subset of familial cardiomyopathy is associated with genetic mutations, over 50% of cardiomyopathy is defined as idiopathic, the mechanisms underlying which are under intensive investigation. SUMO conjugation is a dynamic posttranslational modification that can be readily reversed by the activity of sentrin-specific proteases (SENPs). However, whether SENPs are implicated in heart disease pathophysiology remains unexplored. We observed a significant increase in the level of SENP5, a SUMO isopeptidase, in human idiopathic failing hearts. To reveal whether it plays a role in the pathogenesis of cardiac muscle disorders, we used a gain-of-function approach to overexpress SENP5 in murine cardiomyocytes (SENP5 transgenic, SENP5-Tg). Overexpression of SENP5 led to cardiac dysfunction, accompanied by decreased cardiomyocyte proliferation and elevated apoptosis. The increase in apoptosis preceded other detectable pathological changes, suggesting its causal link to cardiomyopathy. Further examination of SENP5-Tg hearts unveiled a decrease in SUMO attachment to dynamin related protein (Drp1), a factor critical for mitochondrial fission. Correspondingly, the mitochondria of SENP5-Tg hearts at an early developmental stage were significantly larger compared with those in the control hearts, suggesting that desumoylation of Drp1 at least partially accounts for the cardiac phenotypes observed in the SENP5-Tg mice. Finally, overexpression of Bcl2 in SENP5-Tg hearts improved cardiac function of SENP5-Tg mice, further supporting the notion that SENP5 mainly targets mitochondrial function in vivo. Our findings demonstrate an important role of the desumoylation enzyme SENP5 in the development of cardiac muscle disorders, and point to the SUMO conjugation pathway as a potential target in the prevention/treatment of cardiomyopathy. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease".

Heart failure in remission for more than 13 years after removal of a left ventricular assist device

Mechanical cardiac unloading with use of a left ventricular assist device (LVAD) is associated with substantial improvements in left ventricular function and enables subsequent LVAD explantation in some patients. We describe the case of a 35-year-old man with dilated nonischemic cardiomyopathy who was supported with an LVAD for 9 months. After the device was removed, he led a normal life for 13 years and 4 months. However, at 49 years of age, he presented with new signs and symptoms of heart failure, necessitating implantation of a 2nd LVAD. Afterwards, he has remained asymptomatic. This case is unique in that the patient lived a normal life for longer than a decade before renewed left ventricular decompensation necessitated repeat LVAD therapy. Histologic examination revealed few changes between the first device's removal in 1999 and the 2nd device's implantation in 2012.

Advanced atherosclerosis is associated with increased medial degeneration in sporadic ascending aortic aneurysms

OBJECTIVE

The pathogenesis of non-familial, sporadic ascending aortic aneurysms (SAAA) is poorly understood, and the relationship between ascending aortic atherosclerosis and medial degeneration is unclear. We evaluated the prevalence and severity of aortic atherosclerosis and its association with medial degeneration in SAAA.

METHODS AND RESULTS

Atherosclerosis was characterized in ascending aortic tissues collected from 68 SAAA patients (mean age, 62.9 ± 12.0 years) and 15 controls (mean age, 56.6 ± 11.4 years [P = 0.07]) by using a modified American Heart Association classification system. Upon histologic examination, 97% of SAAA patients and 73% of controls showed atherosclerotic changes. Most SAAA samples had intermediate (types 2 and 3, 35%) or advanced atherosclerosis (types ≥ 4; 40%), whereas most control samples showed minimal atherosclerosis (none or type 1, 80%; P < 0.001 after adjusting for age). In a separate analysis, we examined the total incidence and grade distribution of medial degenerative changes among SAAA samples according to atherosclerosis grade. Advanced atherosclerosis was associated with higher grades of smooth muscle cell depletion (P < 0.001), elastic fiber depletion (P = 0.02), elastic fiber fragmentation (P < 0.001), and mucopolysaccharide accumulation (P = 0.04). Aortic diameter was larger in SAAA patients with advanced atherosclerosis than in patients with minimal (P = 0.04) or intermediate atherosclerosis (P = 0.04). Immunostaining showed marked CD3+ T-cell and CD68+ macrophage infiltration, MMP-2 and MMP-9 production, and cryopyrin expression in the medial layer adjacent to atherosclerotic plaque.

CONCLUSIONS

SAAA tissues exhibited advanced atherosclerosis that was associated with severe medial degeneration and increased aortic diameter. Our findings suggest a role for atherosclerosis in the progression of sporadic ascending aortic aneurysms.

Fatal cardiac and renal allograft rejection with lenalidomide therapy for light-chain amyloidosis

We describe a patient who underwent a successful heart and kidney transplant for light-chain amyloidosis. She had an excellent hematologic response to bortezomib/dexamethasone therapy. Follow-up therapy with lenalidomide was started, and the patient quickly had a fatal allograft rejection of the heart and kidney. We present evidence to support the theory that lenalidomide, a known immunomodulator, may have stimulated the immune system and precipitated the fatal rejection episode.

Competition drives clumpy species coexistence in estuarine phytoplankton

Understanding the mechanisms that maintain biodiversity is a fundamental problem in ecology. Competition is thought to reduce diversity, but hundreds of microbial aquatic primary producers species coexist and compete for a few essential resources (e.g., nutrients and light). Here, we show that resource competition is a plausible mechanism for explaining clumpy distribution on individual species volume (a proxy for the niche) of estuarine phytoplankton communities ranging from North America to South America and Europe, supporting the Emergent Neutrality hypothesis. Furthermore, such a clumpy distribution was also observed throughout the Holocene in diatoms from a sediment core. A Lotka-Volterra competition model predicted position in the niche axis and functional affiliation of dominant species within and among clumps. Results support the coexistence of functionally equivalent species in ecosystems and indicate that resource competition may be a key process to shape the size structure of estuarine phytoplankton, which in turn drives ecosystem functioning.

Safety and feasibility of mapping and stem cell delivery in the presence of an implanted left ventricular assist device: a preclinical investigation in sheep

The objective of this study was to determine the safety and feasibility of performing transendocardial electromechanical mapping and mesenchymal precursor stem cell injections after left ventricular assist device (LVAD) implantation in a sheep model of acute myocardial infarction. Six sheep were assigned to either an acute or chronic group. Then we created an acute myocardial infarction in each by occluding the distal left anterior descending coronary artery with a balloon for 90 minutes. All the sheep underwent LVAD implantation 30 days later. On the same day, sheep in the acute group underwent transendocardial cell injections and were euthanized. Sheep in the chronic group received cell injections 2 weeks after LVAD implantation and were euthanized 30 days later. The presence of the LVAD or the use of chest-closure wires did not interfere with electromechanical mapping. Furthermore, no adverse events were observed during electromechanical mapping or the stem cell injections. In all sheep, the LVAD flow rate was approximately 4 L/min during mapping and the injections, and no adjustments were required. Histologic analysis confirmed that the mesenchymal precursor stem cells were successfully delivered. No differences were observed between the acute and chronic groups. In conclusion, our study showed that transendocardial electromechanical mapping and stem cell injections are safe and feasible in the presence of an LVAD. Surgically implanted metal devices, including the LVAD, steel chest-closure wire, and skin staples, were compatible with the electromechanical mapping system.

Remission of chronic anthracycline-induced heart failure with support from a continuous-flow left ventricular assist device

We report the case of a patient who had chronic anthracycline-induced cardiomyopathy that was reversed after treatment with a left ventricular assist device. A 29-year-old woman had undergone anthracycline-based chemotherapy as a teenager in 1991 and 1992 and received a diagnosis of dilated cardiomyopathy 10 years later. Optimal medical therapy had initially controlled the symptoms of heart failure. However, in June 2006, the symptoms worsened to New York Heart Association functional class IV status. We implanted a continuous-flow left ventricular assist device as a bridge to cardiac transplantation; of note, a left ventricular core biopsy at that time showed no replacement fibrosis. The patient's clinical status improved thereafter, enabling left ventricular assist device ex-plantation after 17 months. To our knowledge, this is the first report of the use of left ventricular assist device support to reverse chronic anthracycline-induced heart failure.

Histopathologic correlates of myocardial improvement in patients supported by a left ventricular assist device

BACKGROUND

Left ventricular assist devices unload the failing heart and improve hemodynamic function and tissue architecture. In some patients improvement allows for left ventricular assist device removal. We retrospectively compared histologic features in patients who were weaned off left ventricular assist device support with those who remained on support without evidence of clinical remission.

METHODS

We graded left ventricular core samples taken at implantation on a scale we designed for evaluating severity and extent of fibrosis and hypertrophy. We correlated the grades with a computerized semiquantitative analysis of picrosirius-red and Masson's trichrome-stained sections. We evaluated interstitial (10×), perivascular (20×), and replacement (4×) fibrosis. Hypertrophy was assessed by myocyte diameter, cytoplasmic area, and nuclear/cytoplasmic ratio.

RESULTS

All patients (N=17) underwent left ventricular assist device implantation for heart failure. In eight patients improvement allowed left ventricular assist device removal. The groups did not differ in age (24.1 vs. 25 years, P=.4) or mean time on left ventricular assist device support (506 vs. 414 days, P=.24). All mean measures showed significantly less hypertrophy in the left ventricular assist device-removal group than in the nonremoval group, respectively (cytoplasmic area, 58.00 vs. 77.18 μm(2), P=.021; myocyte diameter, 20.32 vs. 25.35 μm, P=.004; nuclear/cytoplasmic ratio, 11.04 vs. 8.69, P=.053). Although not statistically significant, the left ventricular assist device-removal group tended toward less overall fibrosis than the nonremoval group (11.57 vs. 13.24, P=.214).

CONCLUSIONS

Left ventricular assist device-removal patients had less hypertrophy and fibrosis overall than did nonremoval patients. These findings may help identify patients with a higher probability of left ventricular assist device removal and myocardial recovery.

Partial left ventriculectomy: which patients can be expected to benefit?

BACKGROUND

Although some patients with end-stage heart disease will benefit from a partial left ventriculectomy, no criteria have been found for identifying this group preoperatively. Our experience with partial left ventriculectomy at two institutions-the Texas Heart Institute in Houston, TX, USA, and Dedinje Cardiovascular Institute in Belgrade, Yugoslavia-showed a higher survival rate and better postoperative myocardial function in the Yugoslavian patients.

METHODS

We reviewed data from 42 patients (21 at each center) who had idiopathic cardiomyopathy, a left ventricular end-diastolic dimension of more than 70 mm, wall thickness of 1 cm or greater, and New York Heart Association class III or IV symptoms. The only significant difference in preoperative status between the two groups was duration of symptoms. Histologic specimens, blinded as to origin, were graded with regard to myocyte hypertrophy, cytoplasmic vacuolation, and fibrosis. Computer-assisted myocyte and nuclear morphometry was also performed.

RESULTS

Immediately postoperatively, there were no significant intergroup differences in the reduction in cardiac dimension or in corrections of mitral regurgitation. During 6-month follow-up, however, the Texas Heart Institute patients had a lower cardiac index (1.8 versus 3.0 L x min(-1) x m(-2); p = 0.001) and left ventricular ejection fraction (24% versus 34%; p = 0.006) than the Dedinje Cardiovascular Institute patients. The Texas Heart Institute patients differed from the Dedinje Cardiovascular Institute patients in the degree of severe or moderate changes in myocyte hypertrophy (90% versus 29%; p = 0.0003) and fibrosis (71% versus 29%; p = 0.006), as well as in the measurements of median myocyte diameter (35 +/- 7 microm versus 27 +/- 4 microm; p = 0.0002) and median nuclear size (15 +/- 4 microm versus 12 +/- 2 microm; p = 0.0029).

CONCLUSIONS

In the Texas Heart Institute patients, the significant intergroup difference in clinical outcome may have been related to increased myocyte hypertrophy and fibrosis. Further studies should be performed to determine the usefulness of these criteria in selecting patients for partial left ventriculectomy.

Intensity of infection in AIDS-related intestinal microsporidiosis

To quantify intensity of infection in AIDS-related microsporidiosis, 20 patients with known microsporidiosis submitted stools for quantitative spore counts after staining with a calcofluor white stain. Nine patients collected stools for 24 h, for assessment of daily spore excretion, stool-to-stool variation in spore excretion, and patient-to-patient variation in intensity of infection. The number of organisms seen in small bowel biopsy specimens from 7 patients was compared with quantitative fecal spore excretion. Fecal spore concentration in 20 patients ranged from 4.5x105 to 4.4x108 spores/mL of stool. There was a strong correlation between fecal spore excretion and duodenal biopsy spore counts (r=.82; P<.024). Microsporidium infections in AIDS patients can be quantified by counting spores in stool and by small bowel biopsy. Variations in intensity of infection from patient to patient are great and are similar to those in AIDS-related Cryptosporidium infection.

Immunohistochemistry of matrix metalloproteinases and their inhibitors in thoracic aortic aneurysms and aortic valves of patients with Marfan's syndrome

BACKGROUND

Thoracic aortic aneurysms (TAAs) and valvular insufficiency, the main cardiovascular lesions in Marfan's syndrome, are associated with destruction of connective tissue; however, their pathogenesis remains unclear.

METHODS AND RESULTS

To test the hypothesis that changes in the activity of the matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are responsible for the damage to connective tissue in these lesions, histochemical studies of the immunoreactivity (IR) for MMPs and their tissue TIMPs (MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2) were made in TAAs (n = 7) and aortic valves (n = 5) from 7 patients with Marfan's syndrome. All TAAs showed cystic medial necrosis (CMN), with loss of elastic fibers and smooth muscle cells. Extensive areas of myxoid change were found in all aortic valves. Areas of CMN showed no IR for any MMPs or TIMPs. The IR of smooth muscle cells at the borders of areas of CMN was stronger for all MMPs, especially MMP-2 and MMP-9, than in other regions. The surfaces of disrupted elastic fibers showed IR for MMP-2 and MMP-9. Areas of myxoid change showed similar but less pronounced alterations.

CONCLUSIONS

We hypothesize that the defect in fibrillin-1 in Marfan's syndrome leads to (1) formation of elastin that is abnormally aggregated and more easily degraded by MMPs than is normal elastin, (2) upregulation of the synthesis of MMPs, (3) progressive destruction of connective tissue by these enzymes, and (4) development of TAAs and valvular lesions.

Histologic assessment of Helicobacter pylori status after therapy: comparison of Giemsa, Diff-Quik, and Genta stains

To compare the Giemsa, Diff-Quik, and Genta stains for detection of Helicobacter pylori in gastric biopsy specimens, we stained, coded, and randomized slides, which were then independently reviewed by two pathologists and one trainee. H. pylori was graded from 0 (absent) to 5 (maximal intensity). Negative cases were from recently cured patients to ensure that a background of chronic inflammation was present. The time required to complete the evaluation was tabulated. The pathologists interpreted 72 H. pylori-negative slides, of which 1 (1.3%), 2 (3%), and 3 (4%) were scored positive (each with the score of 1) with Diff-Quik, Genta, and Giemsa stains, respectively (P = ns). Of the 128 H. pylori-positive slides, 5 (4%) had false-negative results with Diff-Quik, 8 with Genta (6%), and 14 with Giemsa stains( 11%). No Grade 2 slides were missed by Genta or Diff-Quik stains, but 3 of 20 were missed by Giemsa stain. The combination of hematoxylin and eosin and Diff-Quik provides accuracy similar to that of the Genta stain but requires more processing time. No stain was excellent after therapy for detecting one or two bacteria per slide; this finding emphasizes the need for obtaining multiple biopsy specimen to exclude failure of H. pylori therapy.

Mast cell involvement in gastritis with or without Helicobacter pylori infection

BACKGROUND & AIMS

Mast cells are initiators and regulators of inflammation, but their role in the human stomach remains unclear. Therefore, the extent and distribution of mast cell involvement in gastritis with or without Helicobacter pylori infection was investigated.

METHODS

Mapped biopsy specimens from 17 H. pylori-positive and 20 H. pylori-negative subjects were examined. Sections were assessed for infection and inflammation and stained with anti-human mast cell tryptase to count mucosal and epithelial mast cells. Density of mast cells in different gastric compartments, their response to infection treatment, and their relationship with other inflammatory cells were evaluated. Mast cell degranulation was evaluated by electron microscopy.

RESULTS

Mast cell density was significantly greater in the mucosa with gastritis, with or without H. pylori infection, than in the mucosa of noninfected normal subjects. In the antrum, density was much greater in H. pylori-infected peptic ulcer subjects than in the other gastritis groups. It also correlated significantly with the intensity of inflammation. Mast cell degranulation was demonstrated by electron microscopy in H. pylori-infected mucosa. Mast cell density in ulcer patients decreased significantly after cure of H. pylori infection.

CONCLUSIONS

Mast cells may be important effector cells in the pathogenesis of gastritis, especially in H. pylori-associated peptic ulcer.

Cure of Helicobacter pylori infection improves gastric acid secretion in patients with corpus gastritis

BACKGROUND

For more than 30 years it has been known that gastric acid secretion is inversely related to the extent and severity of corpal gastritis. We therefore evaluated the effect of cure of Helicobacter pylori infection on basal and pentagastrin-stimulated acid secretion.

METHODS

Basal acid output (BAO) and maximal acid output (MAO) were assessed in 11 H. pylori-infected dyspeptic patients (8 women and 3 men; mean age, 28 years) before and after successful anti-H. pylori therapy.

RESULTS

The gastritis index was significantly lower after therapy and was associated with an increase in both BAO and MAO after cure of the H. pylori infection (BAO from 0.3 mmol/h and MAO from 4.8 mmol/h to 19 mmol/ h). Basal and stimulated acid concentrations also increased (29.1 +/- 36.6 to 54 +/- 31 mmol/l and 72.5 +/- 46 to 120.1 +/- 30 mmol/l, respectively, for basal and stimulated acid concentrations; P < 0.05 for peak and MAO, P = 0.07 for BAO).

CONCLUSION

Gastric acid secretion increased into the normal range after successful treatment of H. pylori infection, suggesting that gastric function can recover to normal or almost normal after cure of H. pylori infection.

Furazolidone, amoxycillin, bismuth triple therapy for Helicobacter pylori infection

BACKGROUND

Metronidazole-resistant Helicobacter pylori are generally the rule in developing countries such as Colombia. Developing countries need an effective, simple and inexpensive non-metronidazole therapy for H. pylori infection.

AIM

To evaluate the combination of bismuth, furazolidone and amoxycillin for the treatment of H. pylori infection in Colombia.

METHODS

Thirty patients with histologically documented H. pylori infection received the combination of bismuth subcitrate 240 mg b.d., furzolidone 100 mg q.d.s. and amoxycillin 500 mg q.d.s. for 14 days. Four or more weeks after ending therapy patients were re-endoscoped and gastric biopsies were obtained and examined using the Genta stain. Each slide was scored for presence, absence and density of H. pylori, active and chronic inflammation, intestinal metaplasia, erosions and atrophy. Cure was defined as the absence of H. pylori.

RESULTS

All patients completed the course of therapy. Twenty-five patients were cured (86%, 95% CI: 65-94%). Mild, well-tolerated side-effects were reported by six patients (20%).

CONCLUSIONS

This combination of bismuth, furazolidone and amoxycillin fulfills the criteria for successful H. pylori therapy and appears particularly well suited for developing countries since it is simple, inexpensive and effective. Furazolidone-containing therapies may become especially useful in the face of a world-wide increase in H. pylori resistance to metronidazole and macrolides.

Adherence of Helicobacter pylori to areas of incomplete intestinal metaplasia in the gastric mucosa

BACKGROUND & AIMS

Helicobacter pylori is not usually found in areas of intestinal metaplasia. Thus, the development of intestinal metaplasia has been viewed as a mechanism by which the stomach eliminates H. pylori. The aim of this study was to evaluate the frequency of H. pylori adherence to intestinal metaplasia in different populations.

METHODS

Mapped gastric biopsy specimens from 378 H. pylori-positive subjects from various geographical regions were examined. Intestinal metaplasia was typed by staining with periodic acid-Schiff/alcian blue and high-iron diamine/alcian blue.

RESULTS

In 32 patients, H. pylori was found in intimate contact with intestinal metaplasia. This was documented by electron microscopy. All areas of intestinal metaplasia showing adherence contained sulfomucins and had no brush border. Posttreatment biopsy specimens from 4 patients whose infection was not cured showed persistence of H. pylori in intestinal metaplasia.

CONCLUSIONS

These patients may have a strain of H. pylori with unusual adhesion characteristics, or their type of intestinal metaplasia may have biochemical properties that make it hospitable for H. pylori. The exclusive association of H. pylori adherence with incomplete intestinal metaplasia (a putative precursor of carcinoma) and its greater frequency in Koreans (a population at risk for gastric cancer) suggest that this phenomenon may play a role in the hypothetical sequence metaplasia > dysplasia > carcinoma.