Acute and short-term fluctuations in gravity are associated with changes in circulatory plasma protein levels

Gravitational changes between micro- and hypergravity cause several adaptations and alterations in the human body. Besides muscular atrophy and immune system impairment, effects on the circulatory system have been described, which can be associated with a wide range of blood biomarker changes. This study examined nine individuals (seven males, two females) during a parabolic flight campaign (PFC). Thirty-one parabolas were performed in one flight day, resulting in ~22 s of microgravity during each parabola. Each participant was subjected to a single flight day with a total of 31 parabolas, totaling 11 min of microgravity during one parabolic flight. Before and after (1 hour (h) and 24 h), the flights blood was sampled to examine potential gravity-induced changes of circulating plasma proteins. Proximity Extension Assay (PEA) offers a proteomic solution, enabling the simultaneous analysis of a wide variety of plasma proteins. From 2925 unique proteins analyzed, 251 (8.58%) proteins demonstrated a differential regulation between baseline, 1 h and 24 h post flight. Pathway analysis indicated that parabolic flights led to altered levels of proteins associated with vesicle organization and apoptosis up to 24 h post microgravity exposure. Varying gravity conditions are associated with poorly understood physiological changes, including stress responses and fluid shifts. We provide a publicly available library of gravity-modulated circulating protein levels illustrating numerous changes in cellular pathways relevant for inter-organ function and communication.

Outcome of Patients Managed by Percutaneous Left Ventricular Assist Device Implantation During On-Hours and Off-Hours

Percutaneous left ventricular assist devices (pVADs) may be used in patients with cardiogenic shock (CS) to stabilize hemodynamics and maintain sufficient end-organ perfusion. Vascular complications are commonly observed in patients with pVAD support. We aimed to assess the relationship between pVAD implantation time and access-site complication rates. This retrospective observational study included all patients who underwent pVAD insertion for the treatment of CS at our university hospital between 2014 and 2021 (n = 224). Depending on the pVAD insertion time, the patients were assigned to the on-hours (n = 120) or off-hours group (n = 104). Both groups had comparable baseline characteristics and comorbidities. The rate of access-site-related complications was higher in the off-hours group than in the on-hours group (26% vs. 10%, p = 0.002). Premature discontinuation of pVAD support to prevent limb ischemia or manage access-site bleeding was required more often in the off-hours group than in the on-hours group (14% vs. 5%, p = 0.016). Pre-existing peripheral artery disease and implantation time off-hours were independent predictors for access-siterelated vascular complications. In conclusion, patients with CS in whom pVAD was inserted during off-hours had higher rates of access-site-related complications and premature discontinuation of pVAD support than those in whom pVAD was inserted during on-hours.

Evaluation of risk factors for cytomegalovirus DNAemia after end of regular prophylaxis after heart transplantation

BACKGROUND

Cytomegalovirus (CMV) infections after heart transplantation (HTx) can cause cardiac allograft vasculopathy. Consequently, monitoring and prophylaxis for cytomegalovirus deoxyribonucleic acid (CMV-DNAemia) within the first weeks after HTx is recommended.

METHODS

All patients who underwent HTx between September 2010 and 2021 surviving the first 90 days (n = 196) were retrospectively reviewed. The patients were divided on the prevalence of CMV-DNAemia during the first postoperative year after the end of the prophylaxis. A total of n = 35 (20.1%) developed CMV-DNAemia (CMV group) and were compared to patients without CMV-DNAemia (controls, n = 139). The remaining patients (n = 22) were excluded due to incomplete data.

RESULTS

Positive donors and negative recipients (D+/R-) and negative donors and positive recipients (D-/R+) serology was significantly increased and D-/R- decreased in the CMV group (p < .01). Furthermore, the mean age was 57.7 ± 8.7 years but only 53.6 ± 10.0 years for controls (p = .03). Additionally, the intensive care unit (p = .02) and total hospital stay (p = .03) after HTx were approximately 50% longer. Interestingly, the incidence of CMV-DNAemia during prophylaxis was only numerically increased in the CMV group (5.7%, respectively, 0.7%, p = .10), the same effect was also observed for postoperative infections. Multivariate analyses confirmed that D+/R- and D-/R+ CMV immunoglobulin G match were independent risk factors for postprophylaxis CMV-DNAemia.

CONCLUSION

Our data should raise awareness of CMV-DNAemia after the termination of regular prophylaxis, as this affects one in five HTx patients. Especially old recipients as well as D+/R- and D-/R+ serology share an elevated risk of late CMV-DNAemia. For these patients, prolongation, or repetition of CMV prophylaxis, including antiviral drugs and CMV immunoglobulins, may be considered.

The impact of gender and frailty on the outcome of older patients with functional mitral regurgitation

AIMS

Functional mitral regurgitation (MR) is the second most common valvular heart disease worldwide and is increasing with age. The present study investigates the gender distribution and 1 year prognosis of older patients (≥65 years) with pharmacologically treated MR in a real-world population with moderate to severe functional MR.

METHODS AND RESULTS

This a single-centre retrospective observational cohort study and included 243 medically treated patients with moderate to severe MR from 2014 to 2020. Echocardiography was performed at baseline. The combined endpoint was hospitalization due to heart failure and all-cause death. There were more female than male patients (42% vs. 58%) without differences regarding age (81 ± 7 years in males vs. 82 ± 8 years in females, P = 0.24). Heart failure symptoms were distributed equally in both groups. Almost half of the patients evidenced a high EuroSCORE II (41%/42%). Atrial fibrillation was frequent, affecting 65% male and 64% female patients (P = 0.89). There were no differences regarding medical treatment. In both genders, two-thirds of the patients displayed MR grade II° (71% (72), and 69% (97)), and one-third showed MR grade III° (29% (30) vs. 31% (44), respectively, P = 0.76). Although males had larger left ventricular end-diastolic diameter, lower ejection fraction (39% (16) vs. 48% (14), P < 0.001), and more dilated left atria. After 1 year, genders did not differ regarding the combined primary endpoint of hospitalization due to heart failure and all-cause mortality (32% (33) for males vs. 29% (41) for females, P = 0.61). One-year mortality was low and equal in both cohorts (11% in males and 9% in females, P = 0.69). In univariate Cox regression proportion hazard model, being female was not associated with the primary endpoint (hazard ratio 0.87 (95% confidence interval 0.55 to 1.37), P = 0.54). Multivariable adjustment for EuroSCORE II and frailty did not result in a significant change regarding the impact of the female gender.

CONCLUSIONS

Despite better left ventricular systolic function, mortality in medically treated older female patients suffering from functional mitral regurgitation is not lower than in males. In this real-world cohort, frailty was a stronger predictor of clinical outcome than gender.

Comparison of costs associated with transcatheter mitral valve repair: PASCAL vs MitraClip in a real-world setting

AIMS

We aimed to conduct a clinical process cost analysis to evaluate all upcoming costs of mitral valve transcatheter edge-to-edge repair (M-TEER) treatment using the MitraClip and the PASCAL repair system.

METHODS

First, we prospectively enrolled 107 M-TEER patients treated with either the PASCAL or MitraClip system and compared all upcoming costs during the M-TEER procedure and the associated in-hospital stay. Second, we retrospectively analysed 716 M-TEER procedures with regard to the occurrence of complications and their associated costs. All materials used in the catheterization laboratory for the procedures were evaluated. The cost analysis considered various expenses, such as general in-hospital costs, device costs, catheter laboratory and material costs.

RESULTS

In the prospective study, 51 patients were treated using the PASCAL system, and 56 were treated using the MitraClip system. The two groups had comparable baseline characteristics and comorbidities. The total in-hospital costs were 25 414 (Interquartile range (IQR) 24 631, 27 697) € in the PASCAL group and 25 633 (IQR 24 752, 28 256) € in the MitraClip group (p = 0.515). The major cost driver was initial material expenditure, mostly triggered by device costs, which were similar to the PASCAL and MitraClip systems. Overall intensive care unit and general ward costs did not differ between the PASCAL and MitraClip groups. In the retrospective analysis, M-TEER-related complications were rare but were associated with higher costs, mainly due to prolonged hospitalisation.

CONCLUSION

The major cost driver of M-TEER was the material expenditure, which was mostly triggered by high device costs. The costs of treating patients were similar for the PASCAL and MitraClip systems. M-TEER-related complications are associated with higher costs, mainly due to prolonged hospitalisation. This analysis provides valuable insights into reducing expenses by modifying the process of M-TEER.

Early Postoperative Neurologic Events Are Associated With Worse Outcome and Fatal Midterm Survival After Adult Heart Transplantation

Background Neurologic events during primary stay in heart transplant (HTx) recipients may be associated with reduced outcome and survival, which we aim to explore with the current study. Methods and Results We screened and included all patients undergoing HTx in our center between September 2010 and December 2022 (n=268) and checked for the occurrence of neurologic events within their index stay. Neurologic events were defined as ischemic stroke, hemorrhage, hypoxic ischemic injury, or acute symptomatic neurologic dysfunction without central nervous system injury. The cohort was then divided into recipients with (n=33) and without (n=235) neurologic events after HTx. Using a multivariable Cox regression model, the association of neurologic events after HTx and survival was assessed. Recipients with neurologic events displayed a longer intensive care unit stay (30 versus 16 days; P=0.009), longer mechanical ventilation (192 versus 48 hours; P<0.001), and higher need for blood transfusion, and need for hemodialysis after HTx was substantially higher (81% versus 55%; P=0.01). Resternotomy (36% versus 26%; P=0.05) and mechanical life support (extracorporeal life support) after HTx (46% versus 24%; P=0.02) were also significantly higher in patients with neurologic events. Covariable-adjusted multivariable Cox regression analysis revealed a significant independent association of neurologic events and increased 30-day (hazard ratio [HR], 2.5 [95% CI, 1.0-6.0]; P=0.049), 1-year (HR, 2.2 [95% CI, 1.1-4.3]; P=0.019), and overall (HR, 2.5 [95% CI, 1.5-4.2]; P<0.001) mortality after HTx and reduced Kaplan-Meier survival up to 5 years after HTx (P<0.001). Conclusions Neurologic events after HTx were strongly and independently associated with worse postoperative outcome and reduced survival up to 5 years after HTx.

Synchronous Donor Heart and Lung Procurement Does Not Impair Outcomes After Heart Transplant

OBJECTIVES

Donor hearts frequently originate from donors whose lungs are also recovered for transplant. Synchronous heart and lung procurement is more complex than procurement ofthe heart alone, and the effects on outcomes are debated. This study examines the effect of synchronous procurement on outcomes in heart transplant recipients.

MATERIALS AND METHODS

This single-center study included patients who received a heart transplant from September 2010 to June 2022. Main outcomes were overall mortality and mortality at 30 days, 3 months, 1 year, and 3 years and morbidity within the first year. We analyzed overall mortality using KaplanMeier survival analysis. Logistic regression was used for the remaining outcomes, adjusting for covariates. P < .05 was considered significant.

RESULTS

Our study included 253 heart transplant recipients (72.3% male, mean age 55.0 years), of which 184 patients (72.7%) received hearts from donors of heart and lung, and 69 (27.3%) received hearts from donors of only hearts. Heart-and-lung donors were younger than heart-only donors (43.2 vs 47.2 years; P = .017). Transplant recipient baseline characteristics were not different between the 2 groups. Receipt of hearts from heart-and-lung donors was not associated with higher overall mortality (P = .33) or mortality at 3 months (P = .199), 1 year (P = .348), or 3 years (P = .375), and even showed better 30-day survival than receipt of hearts from heart-only donors (p=0.035). Recipients of hearts from heart-and-lung donors did not have higher rates of postoperative mechanical circulatory support, resternotomy, or pacemaker implantation within the first year.

CONCLUSIONS

Our study confirms that synchronous heart and lung procurement for transplant is not associated with worse outcomes in heart transplant recipients and that hearts originating from heart-andlung donors may even be associated with improved outcomes.

Reply to Thet et al. Comment on "Oehler et al. Outcome and Midterm Survival after Heart Transplantation Is Independent from Donor Length of Stay in the Intensive Care Unit. Life 2022, 12, 1053"

Myat Soe Thet et al. published a letter [...].

Lactate to Albumin Ratio for Predicting Clinical Outcomes after In-Hospital Cardiac Arrest

In-hospital cardiac arrest (IHCA) is associated with high mortality and poor neurological outcomes. Our objective was to assess whether the lactate-to-albumin ratio (LAR) can predict the outcomes in patients after IHCA. We retrospectively screened 75,987 hospitalised patients at a university hospital between 2015 and 2019. The primary endpoint was survival at 30-days. Neurological outcomes were assessed at 30 days using the cerebral performance category scale. 244 patients with IHCA and return of spontaneous circulation (ROSC) were included in this study and divided into quartiles of LAR. Overall, there were no differences in key baseline characteristics or rates of pre-existing comorbidities among the LAR quartiles. Patients with higher LAR had poorer survival after IHCA compared to patients with lower LAR: Q1, 70.4% of the patients; Q2, 50.8% of the patients; Q3, 26.2% of the patients; Q4, 6.6% of the patients (p = 0.001). Across increasing quartiles, the probability of a favourable neurological outcome in patients with ROSC after IHCA decreased: Q1: 49.2% of the patients; Q2: 32.8% of the patients; Q3: 14.7% of the patients; Q4: 3.2% of the patients (p = 0.001). The AUCs for predicting 30-days survival using the LAR were higher as compared to using a single measurement of lactate or albumin. The prognostic performance of LAR was superior to that of a single measurement of lactate or albumin for predicting survival after IHCA.

Impact of circadian rhythm and daytime variation on outcome after heart transplantation

INTRO

Recently, the impact of circadian rhythm and daytime variation on surgical outcomes has attracted interest. Although studies for coronary artery and aortic valve surgery report contrary results, effects on heart transplantation have not been studied.

METHODS

Between 2010 and February 2022, 235 patients underwent HTx in our department. The recipients were reviewed and categorized according to the start of the HTx procedure - between 04:00 am and 11:59 am (morning, n = 79), 12:00 pm and 07:59 pm (afternoon, n = 68) or 08:00 pm and 03:59 am (night, n = 88).

RESULTS

The incidence of high urgency status was slightly but not significantly increased (p = .08) in the morning (55.7%), compared to the afternoon (41.2%) or night (39.8%). The most important donor and recipient characteristics were comparable among the three groups. The incidence of severe primary graft dysfunction (PGD) requiring extracorporeal life support (morning: 36.7%, afternoon: 27.3%, night: 23.0%, p = .15) was also similarly distributed. In addition, there were no significant differences for kidney failure, infections, and acute graft rejection. However, the incidence of bleeding that required rethoracotomy showed an increased trend in the afternoon (morning: 29.1%, afternoon: 40.9%, night: 23.0%, p = .06). 30-day survival (morning: 88.6%, afternoon: 90.8%, night: 92.0%, p = .82) and 1-year survival (morning: 77.5%, afternoon: 76.0%, night: 84.4%, p = .41) were comparable between all groups.

CONCLUSION

Circadian rhythm and daytime variation did not affect the outcome after HTx. Postoperative adverse events as well as survival were comparable throughout day- and night-time. As the timing of the HTx procedure is rarely possible and depends on the timing of organ recovery, these results are encouraging, as they allow for the continuation of the prevalent practice.

Donor hypernatremia is associated with increased mortality after heart transplantation: A retrospective study

BACKGROUND AND AIMS

Donor hypernatremia has been associated with primary graft dysfunction in heart transplantation (HTx) and is correlated with impaired outcome following liver and renal transplantation. However, controversial data exist regarding the impact of sodium dysregulation on survival. This study aims to investigate the impact of donor sodium levels on early morbidity and short- and midterm survival following HTx.

METHODS

Between September 2010 and June 2021, a total of n = 218 patients underwent HTx in our center. From those, 214 could be included retrospectively in our study. For each donor, sodium levels were collected and different cut-off levels from 145 to 159 mmol/L were investigated by Kaplan-Meier-analysis. Then, recipients were divided in three groups regarding donor sodium: Normonatremia (133-145 mmol/L, n = 73), mild hypernatremia (146-156 mmol/L, n = 105) and severe hypernatremia (>156 mmol/L, n = 35). Recipient and donor variables were reviewed and compared, including peri- and postoperative characteristics and recipient survival after up to 5 years after transplantation.

RESULTS

All patients were comparable regarding baseline characteristics and perioperative parameters. Regarding early mortality, 90-day survival was significantly reduced only in patients with severe donor hypernatremia in comparison to normonatremia (90% vs. 71%, p = .02), but not in mild hypernatremia (89%, p = .89). One-year survival was comparable in all groups (p > .28).

CONCLUSION

Severe donor hypernatremia was associated with reduced short-term survival, while the correlation weakens > 1 year after HTx. As our study is limited due to the nature of its retrospective, single-center approach, future prospective studies are needed to evaluate the importance of donor management with regard to hypernatremia.

Virtual and augmented reality in critical care medicine: the patient's, clinician's, and researcher's perspective

Virtual reality (VR) and augmented reality (AR) are aspiring, new technologies with increasing use in critical care medicine. While VR fully immerses the user into a virtual three-dimensional space, AR adds overlaid virtual elements into a real-world environment. VR and AR offer great potential to improve critical care medicine for patients, relatives and health care providers. VR may help to ameliorate anxiety, stress, fear, and pain for the patient. It may assist patients in mobilisation and rehabilitation and can improve communication between all those involved in the patient's care. AR can be an effective tool to support continuous education of intensive care medicine providers, and may complement traditional learning methods to acquire key practical competences such as central venous line placement, cardiopulmonary resuscitation, extracorporeal membrane oxygenation device management or endotracheal intubation. Currently, technical, human, and ethical challenges remain. The adaptation and integration of VR/AR modalities into useful clinical applications that can be used routinely on the ICU is challenging. Users may experience unwanted side effects (so-called "cybersickness") during VR/AR sessions, which may limit its applicability. Furthermore, critically ill patients are one of the most vulnerable patient groups and warrant special ethical considerations if new technologies are to be introduced into their daily care. To date, most studies involving AR/VR in critical care medicine provide only a low level of evidence due to their research design. Here we summarise background information, current developments, and key considerations that should be taken into account for future scientific investigations in this field.

Chronic insulin resistance deteriorates cardiac mitochondrial quality control in a mouse model of SEC-NAFLD-IR

Background

Insulin resistance and nonalcoholic fatty liver disease (NAFLD) both relate to cardiovascular mortality. Using a mouse model of chronic lipid overload and secondary-NAFLD-induced insulin resistance (SEC-NAFLD-IR), we recently deciphered that SEC-NAFLD-IR already at young age provoked myocardial lipotoxicity with reduced mitochondrial efficiency and increased vulnerability to cardiac ischemia. However, long-term consequences of SEC-NAFLD-IR remain elusive.

Purpose

Here we aimed to elucidate the impact of long-term SEC-NAFLD-IR on multiple mitochondrial quality control (mQC) mechanisms in the heart and its consequences for cardiac function.

Methods

We studied 36 SEC-NAFLD-IR mice (72-week-old). For mechanistic experiments, we applied palmitate-induced insulin resistant murine HL-1 cells. Cardiac mitochondrial dynamics were measured via quantification of mitochondrial morphology and expression of mitochondrial fusion and fission factors (Opa1, Drp1, Fis1, Mfn 1 & 2). Mitophagy level was evaluated via immunofluorescence and protein expression of key mitophagy-related genes (Parkin, NIX, LC3). Mitochondrial biogenesis and mass were examined via quantitation of PGC-1α expression, mtDNA and citrate synthase activity.

Results

72-week-old SEC-NAFLD-IR mice exhibited 21% (p=0.001) and 32% (p&lt;0.001) higher body weight and heart weight compared with controls. Along with elevated oxidative stress, hepatic lipid accumulation and inflammation, 6h-fasted SEC-NAFLD-IR mice were characterized by increased plasma glucose, insulin and cholesterol. SEC-NAFLD-IR mice displayed a cardiac phenotype with 21% higher left ventricular mass (normalized to body weight, p&lt;0.001) and 6% lower ejection fraction compared to controls (73.5% SEM 0.90 vs 69.4% SEM 1.65, p=0.04). We found several advantageous mQC mechanisms suppressed in aged SEC-NAFLD-IR mice including long form OPA1-mediated mitochondrial fusion, Parkin- and NIX-mediated mitophagy. Likewise, mitochondrial biogenesis was suppressed in the aged insulin-resistant heart, which was connected to a 65% downregulation of PGC-1α1 expression (p=0.01). Interestingly, downregulation of cardiac PGC-1α1 in aged SEC-NAFLD-IR mice coincided with upregulation of PARIS, indicating the crucial participation of the Parkin/PARIS pathway in mQC of the insulin-resistant heart. In addition, induction of insulin resistance in murine HL-1 cardiomyocytes also led to increased mitochondrial fragmentation and decreased PGC-1α1 expression.

Conclusion

This study demonstrated that regulation of mitochondrial network and turnover is hampered by SEC-NAFLD-IR in the hearts of aged mice, which may contribute to hypertrophy and cardiac dysfunction in insulin resistance.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Collaborative Research Centre 1116 (German Research Foundation)

Donor hypernatremia is associated with increased mortality after heart transplantation

Objective

Donor hypernatremia has been associated with primary graft dysfunction in heart transplantation and is known to be associated with impaired outcome following liver and renal transplantation. However, controversial data exist regarding the impact of sodium deregulation in patient survival after heart transplantation (HTx). This study aims to investigate the impact of donor sodium levels on early morbidity and short- and midterm survival following HTx.

Methods

Between September 2010 and June 2021, a total of n=218 patients underwent HTx in our centre. From those, 214 could be included retrospectively in our study. For each donor, sodium levels were collected and different cut-off levels from 145 to 159 mmol/l were investigated by Kaplan-Meier-analysis. Then, recipients were divided in three groups regarding donor sodium: Normonatremia (133–145 mmol/l, n=73), mild hypernatremia (146–156 mmol/l, n=105) and severe hypernatremia (&gt;156 mmol/l, n=35). Recipient and donor variables were reviewed and compared, including peri- and postoperative characteristics and recipient survival after up to 5 years after transplantation.

Results

All patients were comparable regarding baseline characteristics and perioperative parameters. Regarding early mortality, 90-day survival was significantly reduced only in patients with severe donor hypernatremia in comparison to normonatremia (see table 1 and fifgure 1, 90% vs. 71%, p=0.02), but not in mild normonatremia (89%, p=0.89). 1-year survival was comparable in all groups (p&gt;0.28).

Conclusion

Donor hypernatremia was associated with reduced short-term survival, while correlation weakens &gt;1 year after HTx. Future prospective studies are needed to confirm the possible cut-off value of 156 mmol/l for donor-acceptancy.

Funding Acknowledgement

Type of funding sources: None.

Full-length transcriptomic analysis in murine and human heart reveals diversity of PGC-1α promoters and isoforms regulated distinctly in myocardial ischemia and obesity

Background

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) acts as a transcriptional coactivator and regulates mitochondrial function. Various isoforms are generated by alternative splicing and differentially regulated promoters. In the heart, total PGC-1α deficiency knockout leads to dilatative cardiomyopathy, but knowledge on the complexity of cardiac isoform expression of PGC-1α remains sparse. Thus, this study aims to generate a reliable dataset on cardiac isoform expression pattern by long-read mRNA sequencing, followed by investigation of differential regulation of PGC-1α isoforms under metabolic and ischemic stress, using high-fat-high-sucrose-diet-induced obesity and a murine model of myocardial infarction.

Results

Murine (C57Bl/6J) or human heart tissue (obtained during LVAD-surgery) was used for long-read mRNA sequencing, resulting in full-length transcriptomes including 58,000 mRNA isoforms with 99% sequence accuracy. Automatic bioinformatic analysis as well as manual similarity search against exonic sequences leads to identification of putative coding PGC-1α isoforms, validated by PCR and Sanger sequencing. Thereby, 12 novel transcripts generated by hitherto unknown splicing events were detected. In addition, we postulate a novel promoter with homologous and strongly conserved sequence in human heart. High-fat diet as well as ischemia/reperfusion (I/R) injury transiently reduced cardiac expression of PGC-1α isoforms, with the most pronounced effect in the infarcted area. Recovery of PGC-1α-isoform expression was even more decelerated when I/R was performed in diet-induced obese mice.

Conclusions

We deciphered for the first time a complete full-length transcriptome of the murine and human heart, identifying novel putative PGC-1α coding transcripts including a novel promoter. These transcripts are differentially regulated in I/R and obesity suggesting transcriptional regulation and alternative splicing that may modulate PGC-1α function in the injured and metabolically challenged heart.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01360-w.

COVID-19 nach Herztransplantation: Erfahrungen eines deutschen Transplantationszentrums

Hintergrund

Die durch SARS-CoV‑2 (Severe acute respiratory syndrome coronavirus type 2) verursachte Erkrankung gilt bei immunsupprimierten Patienten als besonders gefährlich. Patienten nach einer Herztransplantation zählen zu den Gruppen mit langjähriger, meist 3‑facher Immunsuppression. In der Literatur werden schwerwiegende klinische Verläufe beschrieben.

Ziel der Arbeit (Fragestellung)

In dieser Arbeit wird über unsere Erfahrungen mit COVID-19 (coronavirus disease 2019) bei herztransplantierten Patienten an einem deutschen Transplantationszentrum longitudinal über die bisherigen Pandemiewellen berichtet und es erfolgt eine Einordnung dieser in publizierte Erfahrungen anderer Zentren.

Material und Methoden

Alle adulten herztransplantierten Patienten unseres Zentrums, bei denen nach der Herztransplantation eine SARS-CoV-2-Infektion nachgewiesen wurde (n = 12), wurden eingeschlossen und retrospektiv analysiert.

Ergebnisse

Das Durchschnittsalter betrug 61,5 (49 bis 63) Jahre; die Mehrheit der Patienten war männlich (83 %). Die häufigsten Komorbiditäten waren Diabetes (42 %), arterielle Hypertonie (43 %) sowie chronische Niereninsuffizienz (67 %). Bei 50 % erfolgte bei Krankenhausaufnahme eine passive Immunisierung (Rekonvaleszenzplasma/monoklonale Antikörper). Eine Sauerstoffgabe war bei 33 % der Patienten notwendig; nur ein Patient erhielt eine nichtinvasive Ventilation (8 %). Kein Patient benötigte eine invasive Beatmung oder eine mechanische Herz-Kreislauf-Unterstützung (ECMO). Es fanden sich keine neuen kardiovaskulären oder thrombembolischen Ereignisse.

Zusammenfassung

In dieser Kohorte konnten wir longitudinal keine schweren Verläufe oder eine erhöhte Mortalität von COVID-19 in herztransplantierten Patienten detektieren. Prospektive Studien sind notwendig, um in Zukunft bessere Prognoseabschätzungen bei COVID-19 in (herz-)transplantierten Patienten treffen zu können.

IgM-enriched immunoglobulin as adjuvant therapy for heart transplant after infection of left ventricular assist devices

Patients undergoing heart transplantation (HTx) with active infection of left ventricular assist devices (LVAD) are at high risk for postoperative infections. Between 2021 and 2022, five (P1-P5) of a total of n = 44 patients underwent HTx in our department while suffering from LVAD infection. Postoperatively, patients received adjuvant IgM-enriched human intravenous immunoglobulin (IGM-IVIG), consisting of 76% IgG, 12% IgM, and 12% IgA as a novel approach to prevent infective complications. While in P1, P2, and P4, LVAD driveline infection was known before HTx; in P3 and P5, abscess of device pocket was found incidentally during HTx. After a single dose of IGM-IVIG, all patients showed adequate rise in serum immunoglobulins. In the postoperative course, no patient developed infective complications. All patients were successfully discharged and in good condition at the last follow-up. Therefore, IGM-IVIG seems to be an effective adjuvant treatment for patients undergoing HTx with LVAD infections.

Fatal outcome of isolated patients who suffered an in-hospital cardiac arrest

AIM

Isolation of patients in single-patient rooms for infection control precautions leads to less contact with medical staff. Our objective was to assess whether isolated patients who suffer an in-hospital cardiac arrest (IHCA) have lower survival as non-isolated IHCA patients.

METHODS

We screened for IHCA occurrence and the isolation state in 75.987 patients that had been hospitalized from 2016 to 2019 at the university hospital. Primary endpoint was survival to discharge. Neurological outcome was assessed using the cerebral performance category scale.

RESULTS

In five consecutive years, 4,249 out of 75,987 patients (5.6%) had to be isolated for infection control precautions. In-hospital cardiac arrest occurred in 32 (0.8%) of these isolated patients and in 410 out of 71,738 non-isolated patients (0.6%) (p=0.130). Propensity score matching yielded 30 isolated and 30 non-isolated patients who suffered an IHCA, without a difference in baseline characteristics and characteristics of cardiac arrests between the groups. Only one out of 30 isolated patients (3.3%) survived to discharge after IHCA compared to 11 non-isolated patients (36.6%) (risk difference, 33.3% [95% CI, 14.9%-51.7%]. None of the 30 isolated patients were discharged with good neurological outcomes compared to nine out of 30 non-isolated IHCA patients (30%) (risk difference, 30% [95% CI, 13.6%-46.4%]). In the multivariate analysis, patient isolation was an independent predictor of poor survival after IHCA (OR, 18.99; 95% CI, 2.467-133.743).

CONCLUSIONS

Isolation of patients for infection control precautions is associated with considerable poorer survival and neurological outcome in case these patients are suffering an IHCA.

Intracerebral bleeding in donors is associated with reduced short-term to midterm survival of heart transplant recipients

Aim

The quality of the donor heart is known to have a crucial effect on outcome after heart transplantation (HTx). Although leading to brain death in the end, the initial cause of death of the donor and its potential influences on organ quality are heterogeneous. However, it is still controversial to which extent the donor cause of death is associated with outcome or survival post‐HTx.

Methods and results

We included all patients undergoing HTx in our centre between September 2010 and June 2021 (n = 218). Recipients were divided in five groups related to their donor cause of death: intracerebral bleeding (‘ICB’, n = 95, 44%), traumatic brain injury (‘trauma’, n = 54, 25%), hypoxic brain damage (‘hypoxic’, n = 34, 16%), cerebrovascular (‘vascular’, n = 15, 7%), or other cause (n = 20, 9%). Baseline characteristics, perioperative parameters, and survival after 30 and 90 days as well as 5 years after transplantation were collected.

Results

Intracerebral bleeding in donors compared with traumatic brain injury is associated with higher probability of need for ECLS post‐HTx (35% vs. 19%, P = 0.04) and significantly reduced survival up to 5 years post‐HTx (i.e. 1 year survival: 61% vs. 95%, P < 0.0001). Although other conditions also show significant changes in outcome and survival, the effect is strongest for ICB, where survival is also reduced compared with all other causes (1 year: 61% vs. 89%, P < 0.0001).

Conclusions

In this retrospective analysis, donor cause of death is associated with differing outcome and survival after HTx. Intracerebral bleeding hereby shows strongest decline in outcome and survival in comparison with all other causes.

COVID-19 pandemic deteriorates aftercare attendance in heart transplant recipients independently of perceived impact on social life

BACKGROUND

Heart transplant (HTx) recipients are at an increased risk of developing infections or malignancies due to immunosuppressive medication. Thus, regular aftercare in those patients is of utmost importance. The extent of collateral damage due to the COVID-19 pandemic (delayed or canceled clinical visits and diagnostics) on high-risk patients is yet unknown. We believe that, especially for HTx-patients, data acquisition on potential pandemic-related nonattendance is crucial to improve clinical care in the future. Therefore, we aim to decipher possible COVID-19-related alterations in attendance to clinical care after HTx using a survey-based approach.

METHODS

HTx recipients, 2 years beyond transplantation were selected (n = 75). We filed a paper-based questionnaire or an online survey containing nine items about COVID-19-related exceptional circumstances. Fifty-two patients (69%) returned fully answered questionnaires.

RESULTS

A perceived impact on daily life was evident with 79% of all patients, reporting a moderate-to-severe negative influence of the COVID-19 pandemic on daily routine. We detected increased nonattendance of clinical care during the COVID-19 pandemic compared to prepandemic time (38 vs. 6%, p < .0001). The various diagnostic modalities of aftercare were heterogeneously affected, ranging from 2% nonattendance for influence vaccination and 18% for colonoscopy. Off note, nonattendance to clinical care within the pandemic was independent of perceived impact of the pandemia on daily life (p > .68).

CONCLUSIONS

For the first time, we objectively demonstrate a significant decrease in attendance to clinical care in HTx recipients during the COVID-19 pandemic. Efforts are needed to increase attendance in this highly vulnerable patient cohort.

Removal of Electrophysiological Devices in the Context of Heart Transplantation: Comparison of Combined and Staged Extraction Procedures

BACKGROUND

 During heart transplantation (HTx), tip of the leads of cardiac implantable electrophysiological devices (CIEPD) has to be cut when resecting the heart. Timing of the removal of the remaining device and leads is still discussed controversially.

METHODS

 Between 2010 and 2021, n = 201 patients underwent HTx, of those n = 124 (61.7%) carried a present CIEPD. These patients were divided on the basis of the time of complete device removal (combined procedure with HTx, n = 40 or staged procedure, n = 84).

RESULTS

 CIEPD was removed 11.4 ± 6.7 days after the initial HTx in staged patients. Dwelling time, number of leads as well as incidence of retained components (combined: 8.1%, staged: 7.7%, p = 1.00) were comparable between both groups. While postoperative incidence of infections (p = 0.52), neurological events (p = 0.47), and acute kidney injury (p = 0.44) did not differ, staged patients suffered more often from primary graft dysfunction with temporary mechanical assistance (combined: 20.0%, staged: 40.5%, p = 0.03). Consecutively, stay on intensive care unit (p = 0.02) was prolonged and transfusions of red blood cells (p = 0.15) and plasma (p = 0.06) as well as re-thoracotomy for thoracic bleeding complications (p = 0.10) were numerically increased in this group. However, we did not observe any differences in postoperative survival.

CONCLUSION

 Presence of CIEPD is common in HTx patients. However, the extraction strategy of CIEPD most likely did not affect postoperative morbidity and mortality except primary graft dysfunction. Especially, retained components, blood transfusions, and infective complications are not correlated to the timing of CIEPD removal.

Cytomegalovirus mismatch after heart transplantation: Impact of antiviral prophylaxis and intravenous hyperimmune globulin

Objective

Cytomegalovirus (CMV) infections are correlated with complications following heart transplantation (HTx) and impaired outcome. The impact of a serologic mismatch between donor and recipient and the necessity of prophylactic virostatic medication is still a matter of concern.

Methods

We retrospectively reviewed all patients that underwent HTx between 2010 and 2020 in our department. The recipients (n = 176) could be categorized into four risk groups depending on their serologic CMV matching (D⁺/R⁻ = donor CMV‐IgG positive and recipient CMV‐IgG negative, n = 32; D⁻/R⁺, n = 51; D⁻/R⁻, n = 35; D⁺/R⁺, n = 58). All patients followed the same protocol of CMV prophylaxis with application of ganciclovir/valganciclovir and intravenous CMV hyperimmune globulin.

RESULTS

Incidence of postoperative morbidity such as primary graft dysfunction, neurological events, infections, and graft rejection were comparable between all groups (p > .05). However, the incidence of postoperative acute kidney injury with hemodialysis was by trend increased in the D⁻/R⁺ group (72.0%) compared to the other groups. In‐hospital CMV‐DNAemia was observed in serologic positive recipients only (D⁺/R⁻: 0.0%, D⁻/R⁺: 25.0%, D⁻/R⁻: 0.0%, D⁺/R⁺: 13.3%, p < .01). During the first year, a total of 18 patients developed CMV‐DNAemia (D⁺/R⁻: 31.6%, D⁻/R⁺: 31.9%, D⁻/R⁻: 3.4%, D⁺/R⁺: 11.1%, p = .03).

Conclusions

Seropositive recipients carry an important risk for CMV‐DNAemia. However, we did not observe differences in perioperative morbidity and mortality regarding CMV matching, which might be related to regularly administer prophylactic virostatics and additional CMV‐IVIG for risk constellations. For high‐risk constellation, long‐term application of CMV‐IVIG during the first year after transplant may be beneficial.

Outcome of patients with non-ischaemic cardiogenic shock supported by percutaneous left ventricular assist device

Aims

Percutaneous left ventricular assist devices (pVADs) are used to haemodynamically stabilize patients with cardiogenic shock (CS) caused by acute myocardial infarction (AMI). One out of every two patients has a non‐ischaemic cause of CS, and these patients differ profoundly from patients with AMI‐related CS. We assessed the usefulness of pVAD support for patients with non‐ischaemic CS.

Methods and results

We analysed 106 patients with CS and Impella® support between 2015 and 2018. CS was non‐ischaemic in 36 patients and AMI‐related in 70 patients. Compared with the AMI group, those in the non‐ischaemic group were significantly younger [median age 62 (50.8, 70.8) years vs. 68 (58.0, 75.5) years, P = 0.007] and had more patients with severely reduced left ventricular function (94% vs. 79%, P = 0.035) and worse glomerular filtration rate [45 (27, 57) mL/min vs. 60 (44, 78) mL/min]. Propensity score matching yielded 31 patients with non‐ischaemic CS and 31 patients with AMI‐related CS, without a difference in baseline laboratory values or comorbidities. In both groups, pVAD support was performed along with haemodynamic stabilization, reduction of catecholamines and normalization of lactate levels. In 7 days, systolic blood pressure increased from 91 (80, 101) mmHg at baseline to 100 (100, 120) mmHg in the non‐ischaemic CS group (P = 0.001) and 89 (80, 100) mmHg at baseline to 112 (100, 128) mmHg in the AMI‐related CS group (P = 0.001). Moreover, in 7 days, the need of catecholamines (calculated as vasoactive‐inotropic score) decreased from 32.0 (11.1, 47.0) at baseline to 5.3 (0, 16.1) in the non‐ischaemic group (P = 0.001) and from 35.2 (18.11, 67.0) to zero (0, 0) in the AMI‐related CS group (P = 0.001). Lactate level decreased from 3.8 (2.8, 5.9) mmol/L at baseline to 1.0 (0.8, 2.1) mmol/L (P = 0.001) in the non‐ischaemic CS group and from 3.8 (2.6, 6.5) mmol/L to 1.2 (1.0, 2.0) mmol/L in the AMI‐related group (P = 0.001).

In the non‐ischaemic CS group, eight patients (25.8%) were upgraded to veno‐arterial extracorporeal membrane oxygenation (VA‐ECMO) or long‐term mechanical circulatory support. Two of these upgraded patients received heart transplantation. In the AMI group, eight patients (25.8%) were upgraded to VA‐ECMO or long‐term mechanical circulatory support. Ninety‐day survival did not significantly differ between the groups (non‐ischaemic CS group 48.4%, AMI‐related CS group 45.2%, P = 0.799).

Conclusions

pVAD support is useful for haemodynamic stabilization of patients with non‐ischaemic CS and is valuable as a bridge to patients' recovery or long‐term left ventricular support and heart transplantation.

Moderate acceptance of COVID-19 vaccination in patients pre- and post-heart transplantation: Experiences from a German Transplant Centre

INTRODUCTION AND OBJECTIVES

Patients awaiting heart transplantation (HTx) are at increased risk developing severe coronavirus disease 2019 (COVID-19). Patients supported by a left ventricular assist device (LVAD) face additional risks due to coagulopathies during COVID-19. Following HTx, elevated risk factors for severe COVID-19 persist due to chronic immunosuppression and frequent comorbidities. Taken together, COVID-19 vaccination is of critical importance in all three patient cohorts. Here, we report our experience to deliver COVID-19 vaccination in a German transplant center.

METHODS AND RESULTS

We screened 211 patients for contraindications and offered the remaining 186 eligible patients COVID-19 vaccination. Of those, 133 patients (71%) accepted the offer and were vaccinated. Acceptance of vaccination differed between HTx recipients (84 of 113, 74%), patients on the waiting list (34 of 47, 72%), and patients with LVAD support (28 of 50, 56%). The LVAD cohort demonstrated lower acceptance levels for vaccination compared to HTx recipients and patients awaiting HTx (74% vs. 56%; p = 0.028).

CONCLUSION

We demonstrate for the first time only moderate acceptance levels of COVID-19 vaccination in HTx recipients and candidates on the waiting list compared to general population, despite perceived high-risk for severe disease. Additionally, those supported by LVAD have even lower adherence. Efforts may need to be made to increase acceptance in this vulnerable as well as cost-intensive patient cohort.

Full-length-transcriptomic analysis in mice and human heart using Single-Molecule Real-time Sequencing (SMRT) identified 15 novel isoforms and a novel promoter region of PGC1-alpha

Background

Alternative splicing is a process by which exons within a pre-mRNA are joined or skipped, resulting in isoforms being encoded by a single gene. Alternative Splicing affecting transcription factors may have substantial impact on cellular dynamics. The PPARG Coactivator 1 Alpha (PGC1-α), is a major modulator in energy metabolism. Data from murine skeletal muscle revealed distinctive isoform patterns giving rise to different phenotypes, i.e. mitogenesis and hypertrophy. Here, we aimed to establish a complete dataset of isoforms in murine and human heart applying single-molecule real-time (SMRT)-sequencing as novel approach to identify transcripts without need for assembly, resulting in true full-length sequences. Moreover, we aimed to unravel functional relevance of the various isoforms during experimental ischemia reperfusion (I/R).

Methods

RNA-Isolation was performed in murine (C57Bl/6J) or human heart tissue (obtained during LVAD-surgery), followed by library preparation and SMRT-Sequencing. Bioinformatic analysis was done using a modified IsoSeq3-Pipeline and OS-tools. Identification of PGC1-α isoforms was fulfilled by similarity search against exonic sequences within the full-length, non-concatemere (FLNC) reads. Isoforms with Open-Reading-Frame (ORF) were manually curated and validated by PCR and Sanger-Sequencing. I/R was induced by ligature of the LAD for 45 min in mice on standard chow as well as on high-fat-high-sucrose diet. Area At Risk (AAR) and remote tissue were collected three and 16 days after I/R or sham-surgery (n=4 per time point). Promotor patterns were analyzed by qPCR.

Results

Deciphering the full-length transcriptome of murine and human heart resulted in ∼60000 Isoforms with 99% accuracy on mRNA-sequence. Focusing on murine PGC1-α-isoforms we discovered and verified 15 novel transcripts generated by hitherto unknown splicing events. Additionally, we identified a novel Exon 1 originating between the known promoters followed by a valid ORF, suggesting the discovery of a novel promoter. Remarkably, we found a homologous novel Exon1 in human heart, suggesting conservation of the postulated promoter.

In I/R the AAR exhibited a significant lower expression of established and novel promoters compared to remote under standard chow 3d post I/R. 16d post I/R, the difference between AAR & Remote equalized in standard chow while remaining under High-Fat-Diet.

Conclusion

Applying SMRT-technique, we generated the first time a complete full-length-transcriptome of the murine and human heart, identifying 15 novel potentially coding transcripts of PGC1-α and a novel exon 1. These transcripts are differentially regulated in experimental I/R in AAR and remote myocardium, suggesting transcriptional regulation and alternative splicing modulating PGC1-α function in heart. Differences between standard chow and high fat diet suggest impact of impaired glucose metabolism on regulatory processes after myocardial infarction.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Collaborative Research Centre 1116 (German Research Foundation)

Physiological Effects of Beetroot in Athletes and Patients

Dietary supplementation with beetroot juice (BRJ), a naturally rich source of nitrate, is an area of considerable interest to elite athletes as well as recreational exercisers. Nitrate and nitrite have previously been thought of as mainly final elimination products of nitric oxide (NO), but this view has been challenged and evidence indicates that these compounds can be converted to NO in vivo. We conducted a narrative review summarizing the literature regarding evidence of beetroot used as dietary supplement and its effects on training physiology and athletic performance in healthy and diseased populations. The databases PubMed and Web of Science were used to obtain articles. It was evident that BRJ supplementation had an effect on oxygen cost and consumption during exercise by more efficient adenosine triphosphate (ATP) production in combination with lower ATP consumption. However, the effect seems to be dependent on dose and duration. Effect on exercise performance is conflicting, time to exhaustion seems to increase but its effect on time-trial performance needs further elucidation. Ergogenic benefits might depend on individual aerobic fitness level, where individuals with lower fitness level may gain higher benefits regarding athletic performance. Dietary nitrate supplementation appears to have some effect on training performance in patients with peripheral artery disease, heart failure, and chronic pulmonary obstructive disease. However, larger randomized controlled trials are necessary to determine the overall utility of beetroot as a dietary supplement.

Genomic structural variations lead to dysregulation of important coding and non-coding RNA species in dilated cardiomyopathy

The transcriptome needs to be tightly regulated by mechanisms that include transcription factors, enhancers, and repressors as well as non‐coding RNAs. Besides this dynamic regulation, a large part of phenotypic variability of eukaryotes is expressed through changes in gene transcription caused by genetic variation. In this study, we evaluate genome‐wide structural genomic variants (SVs) and their association with gene expression in the human heart. We detected 3,898 individual SVs affecting all classes of gene transcripts (e.g., mRNA, miRNA, lncRNA) and regulatory genomic regions (e.g., enhancer or TFBS). In a cohort of patients (n = 50) with dilated cardiomyopathy (DCM), 80,635 non‐protein‐coding elements of the genome are deleted or duplicated by SVs, containing 3,758 long non‐coding RNAs and 1,756 protein‐coding transcripts. 65.3% of the SV‐eQTLs do not harbor a significant SNV‐eQTL, and for the regions with both classes of association, we find similar effect sizes. In case of deleted protein‐coding exons, we find downregulation of the associated transcripts, duplication events, however, do not show significant changes over all events. In summary, we are first to describe the genomic variability associated with SVs in heart failure due to DCM and dissect their impact on the transcriptome. Overall, SVs explain up to 7.5% of the variation of cardiac gene expression, underlining the importance to study human myocardial gene expression in the context of the individual genome. This has immediate implications for studies on basic mechanisms of cardiac maladaptation, biomarkers, and (gene) therapeutic studies alike.

The Role of Quality Control in Targeted Next-generation Sequencing Library Preparation

Next-generation sequencing (NGS) is getting routinely used in the diagnosis of hereditary diseases, such as human cardiomyopathies. Hence, it is of utter importance to secure high quality sequencing data, enabling the identification of disease-relevant mutations or the conclusion of negative test results. During the process of sample preparation, each protocol for target enrichment library preparation has its own requirements for quality control (QC); however, there is little evidence on the actual impact of these guidelines on resulting data quality. In this study, we analyzed the impact of QC during the diverse library preparation steps of Agilent SureSelect XT target enrichment and Illumina sequencing. We quantified the parameters for a cohort of around 600 samples, which include starting amount of DNA, amount of sheared DNA, smallest and largest fragment size of the starting DNA; amount of DNA after the pre-PCR, and smallest and largest fragment size of the resulting DNA; as well as the amount of the final library, the corresponding smallest and largest fragment size, and the number of detected variants. Intriguingly, there is a high tolerance for variations in all QC steps, meaning that within the boundaries proposed in the current study, a considerable variance at each step of QC can be well tolerated without compromising NGS quality.

Microdissection and DOP-PCR-based reverse chromosome painting as a fast and reliable strategy in the analysis of various structural chromosome abnormalities

Reverse chromosome painting has become a powerful tool in clinical genetics for the characterization of cytogenetically unclassifiable aberrations. In this report, the application of a sensitive and rapid procedure for the complete and precise identification of four different de novo structural chromosome abnormalities is presented. These chromosome rearrangements include a marker derived from chromosome 3(cen-q11), an interstitial deletion of chromosome 13 [del(13)(q14q22)], an unbalanced translocation [46,XY, -4, +der(4)t(4;8)(p 15.2;p21.1)] leading to Wolf-Hirschhorn syndrome, and a partial inverted duplication in conjunction with a partial deletion of chromosome 5p [46,XX, -5, +der(5)(:p13-p15.1::p15.1-qter)] which is responsible for the manifestation of the cri-du-chat syndrome. The importance of a fast and reliable evaluation of complex chromosome aberrations in pre- and postnatal diagnosis with regard to comprehensive genetic counselling is emphasized.

Regional distribution and characterization of nitric oxide synthase activity in the brain of the common marmoset

The distribution of nitric oxide synthase (NOS) within the brain of the common marmoset, a non-human primate species, was investigated using the [3H]L-citrulline formation assay and Western blot analysis. No hemispheric asymmetry of specific NOS activity was shown. The highest levels of NOS were found in the putamen and caudate nucleus--more than twice those in the cortex and the cerebellum, the brain regions with the lowest activities. The regional distribution pattern was similar to that in the ferret brain and contrasted to that in the mouse and bovine brain. Analysis of NOS catalytic activities in subcellular fractions revealed marked differences in the subcellular localization. Neuronal NOS accounted mainly for the measured catalytic activity in the brain. Differences in the regional distribution pattern of brain NOS activity among species may be indicative of diversities in the functional role of nitric oxide and NOS in mammals.

Nutritional insult and recovery in the neonatal rat cerebellum: insulin-like growth factors (IGFs) and their binding proteins (IGFBPs)

Alterations in growth caused by neonatal malnutrition may be mediated in part by changes in insulin-like growth factor (IGF) and IGF binding protein (IGFBP) expression. Since the neonatal rat cerebellum undergoes a transient, proliferative growth phase in the first two weeks of life, this structure was used to determine whether alterations in circulating and tissue IGFs and IGFBPs may mediate effects of impaired nutrition on the developing central nervous system. Gravid rats were placed on a 4% (protein-calorie deprived, D) or 20% (control, C) protein diets one day prior to delivery and allowed to nurse their pups postpartum. Pups nursing from D mothers received a limited volume of milk and were calorically deprived. Some litters of D pups were foster fed by C mothers from day 8 to day 13 to constitute a recovery group (R). Cerebellar weight, protein, and DNA content in D pups were less than C, p < 0.001. In R pups, DNA and protein returned to C levels by day 13. Between days 6 and 13, serum IGF-I levels rose from 158 +/- 18 to 210 +/- 18 ng/ml in C but remained low in D (47 +/- 6 ng/ml and 25 +/- 3 ng/ml), respectively. In R pups, serum IGF-I partially recovered during this time, and increased from 49 +/- 5 to 110 +/- 7 ng/ml. In cerebellar extracts, IGF-I levels in both C and D were lower at 13 days than at 6 days, p < 0.05 and p < 0.005, respectively. IGF-I levels in C were similar at day 9 and day 11 and were consistently higher than D (11.84 +/- 0.83 vs 8.56 +/- 0.92 ng/g, p < 0.02 C vs D). In R, IGF-I was reduced on day 11, but was similar to C on day 13. Serum IGF-II in D was lower than C, p < 0.01, and did not increase in the R group. Cerebellar IGF-II was virtually undetectable in either group. Immunoprecipitation and ligand blotting studies of serum demonstrated that circulating levels of 32-34 K IGFBPs were increased 3-4 fold in D vs C, reflecting high levels of IGFBP-1 and/or -2, while levels of 24 K IGFBP-4 were lower in D vs C. By contrast, immunoprecipitation and ligand blotting of cerebellar extracts detected IGFBP-2 and -4, but did not detect IGFBP-1. Further, tissue levels of IGFBP-2 were not increased in D vs C, and levels of IGFBP-4 also were not markedly affected by nutritional deprivation. These results suggest that alterations in tissue content and the availability of IGF-I only modestly contributed to the effects of impaired nutrition in the developing central nervous system.

A novel DNA/protein complex interacts with the insulin-like growth factor binding protein-1 (IGFBP-1) insulin response sequence and is required for maximal effects of insulin and glucocorticoids on promoter function

Glucocorticoids stimulate and insulin inhibits hepatic production of IGFBP-1 at the level of gene transcription. We previously identified contiguous insulin and glucocorticoid response sequences in the proximal rat IGFBP-1 promoter. This insulin response sequence (IRS) is palindromic (CAAAACAAACTTATTTTG) and each half resembles an IRS in the phosphoenolpyruvate carboxykinase (PEPCK) gene. We have reported that both the IGFBP-1 and PEPCK IRSs bind hepatocyte nuclear factor-3 (HNF-3) proteins [1]. We now report that IRSs from the IGFBP-1 and PEPCK, as well as an IRS which also binds HNF-3 in the rat tyrosine aminotransferase (TAT) gene, also interact with another DNA/protein complex in gel shift studies. Further, methylation interferences studies, gel shift and transient transfection studies with site-specific mutations identified a single base in the first half of the IRS that is critical both for interactions with proteins in this complex, and for maximal effects of insulin and glucocorticoids, on promoter function. Of note, a 250-fold excess of an oligo containing a C/EBP binding site (but not other AT-rich sequences) inhibits the formation of this complex in gel shift assays. Nevertheless, interactions with this C/EBP site are negligible at lower titers (< or = 100-fold excess), and antibodies against known C/EBP proteins do not react with this complex. Similarly, preincubation with CHOP, a truncated member of the C/EBP family which contains a beta-leucine zipper domain, does not prevent or alter the mobility of this novel DNA/protein complex, indicating that components of this complex do not form heterodimers with beta-ZIP proteins. We conclude that HNF-3 proteins and this novel C/EBP-related DNA/protein complex may play an important role in mediating interactions between glucocorticoids and insulin in the regulation of IGFBP-1 and perhaps multiple hepatic genes.

Dideoxy sequencing and structural analysis of the rat insulin-like growth factor binding protein-1 gene

Insulin-like growth factor binding protein-1 (IGFBP-1) is an important modulator of IGF bioavailability. To facilitate studies of IGFBP-1 regulation and function in rodent models, we cloned the rat IGFBP-1 gene and analyzed its structure by dideoxy sequencing. The rat IGFBP-1 gene is relatively small (approximately 5 kb) and contains 4 exons and 3 introns, similar to the human IGFBP-1 gene.

Circulating levels of insulin-like growth factor binding protein-1 (IGFBP-1) and hepatic mRNA are increased in the small for gestational age (SGA) fetal rat

Insulin-like growth factors (IGFs) circulate in association with a family of specific binding proteins (BPs). Recently, we reported that circulating levels of IGFBP-1 and IGFBP-2 are increased in streptozotocin-diabetic adult rats and are differentially regulated in accordance with insulin and metabolic status. Since IGF BPs appear to be important modulators of IGF bioactivity in post-natal life, we asked whether serum levels of IGF BPs also might be altered in utero when the delivery of maternal nutrients is restricted and fetal growth is impaired. Bilateral uterine artery ligation or sham surgery was performed on maternal rats on d 19 of gestation (term 21.5 d). One day after ligation (d 20), fetuses were (SGA) compared to shams (3.1 +/- 1 vs 3.7 +/- 0.2 g, p less than .02) and serum levels of glucose (70 +/- 5 vs 96 +/- 6 mg/dL, p less than .01) and insulin (62 +/- 4 vs 138 +/- 14 microU/mL) also were reduced. In contrast, serum [125I]IGF-I binding activity was markedly increased in SGA litters compared to sham (65 +/- 5% maximum binding with 2.5 microL/mL SGA serum vs 14 +/- 3% for sham serum, p less than .001), and correlated with fetal weight (r = -0.539, p less than .05) and insulin (r = -0.622, p less than .05). Ligand blotting with [125I]IGF-I revealed that serum levels of IGFBP-1 (32 K) were greater in SGA than shams, while immunoblotting with specific antiserum demonstrated that levels of IGFBP-2 (34 K), the major fetal rat IGF BP, were similar in serum from SGA and shams litters. Affinity labeling and immunoprecipitation confirmed that IGF binding activity is increased in SGA, due largely to increased availability of IGFBP-1. In addition, Northern analysis of hepatic RNA revealed that the abundance of IGFBP-1 mRNA is increased in the SGA fetal rat, while hepatic mRNA for IGFBP-2 is similar in SGA and sham-operated litters. We conclude that circulating levels of IGFBP-1 and the abundance of hepatic mRNA are increased in the SGA fetal rat. IGFBP-1 may be an important modulator of IGF bioactivity and somatic growth in utero.