Heart transplant recipients with confirmed 2019 novel coronavirus infection: The Detroit experience

A chronic immunosuppressed state as in solid organ transplant recipients is a reported risk factor for the novel 2019 coronavirus infection. Patients with a history of orthotopic heart transplant (OHT) at a tertiary care transplant center in Detroit, Michigan were retrospectively reviewed from March until May 2020. Clinical parameters and outcomes of 5 OHT recipients and one combined heart–lung recipient with confirmed SARS-CoV-2 were obtained. The cohort was predominately African American males with median age of 59 years (interquartile range, 48.25-73.25). All patients were classified as having mild–moderate disease; none required intubation or ICU admission with no deaths. The most common presenting symptoms were fever and shortness of breath 83% (n = 5), followed by cough and chills 67% (n = 4). All admitted patients (n = 5) received hydroxychloroquine and 3 received high-dose steroids. Antimetabolites were held for 2 patients (33.3%). The calcineurin inhibitor trough goal was decreased in only 1 patient; 3 other patients, without change in goal, required calcineurin inhibitor dosage reduction. Two patients requiring readmission presented 7 and 23 days after initial symptoms onset. In conclusion, our experience with OHT patients infected by the SARS-CoV-2 virus did not have an elevated risk of severe infection. Impact of modifying immunosuppression remains unclear.     

Characterization of putative regulatory isoforms of porcine tumor necrosis factor receptor 2 in endothelial cells

Tumor necrosis factor α (TNFα) and its receptors contribute to rejection of transplanted cells and organs. To elucidate how TNFα affects xenograft rejection, we previously cloned the cDNA of pig TNF-receptor 2 (pTNFR2) and found four isoforms: one comprising the full receptor with four cysteine-rich domains (CRD), a shorter variant (pTNFR2ΔE7-10) encoding for a soluble isoform, another lacking exon 4 (pTNFR2ΔE4) displaying only 3 CRD and poor ligand binding, and the smallest one generated by the two alternative splicings. All isoforms contained the pre-ligand assembly domain (PLAD) responsible for receptor trimerization. We now investigated their roles by structural, expression, and subcellular localization studies. Structural in silico analyses identified four amino acids potentially involved in TNFα binding and lacking in pTNFR2ΔE4. Quantitative RT-PCR determined regulated expression affecting the two pTNFR2 alternative splicings in cytokine-stimulated porcine aortic endothelial cells (PAEC). Particularly, human IL-1α and TNFα produced a strong mRNA upregulation of all isoforms, being the full receptor the predominant one. However, expression of pTNFR2 on PAEC did not correlate with mRNA and decreased after 24-hour exposure to IL-1α or TNFα. Notably, confocal microscopy confirmed the presence of pTNFR2 inside and on the plasma membrane, whereas pTNFR2ΔE4 located only intracellularly. Most interestingly, FRET analyses showed that membrane-bound isoforms pTNFR2 and pTNFR2ΔE4 colocalized intracellularly and associated through the PLAD. Our data show that pTNFR2ΔE4 bind and may retain the full receptor intracellularly. This mechanism has not been described in other species and represents a particularity that may affect the pathophysiology of pig xenografts.     

Side‐effects of thiamethoxam on the brain andmidgut of the africanized honeybee Apis mellifera (Hymenopptera: Apidae)

The development of agricultural activities coincides with the increased use of pesticides to control pests, which can also be harmful to nontarget insects such as bees. Thus, the goal of this work was assess the toxic effects of thiamethoxam on newly emerged worker bees of Apis mellifera (africanized honeybee—AHB). Initially, we determined that the lethal concentration 50 (LC₅₀) of thiamethoxam was 4.28 ng a.i./μL of diet. To determine the lethal time 50 (LT₅₀), a survival assay was conducted using diets containing sublethal doses of thiamethoxam equal to 1/10 and 1/100 of the LC_50. The group of bees exposed to 1/10 of the LC₅₀ had a 41.2% reduction of lifespan. When AHB samples were analyzed by morphological technique we found the presence of condensed cells in the mushroom bodies and optical lobes in exposed honeybees. Through Xylidine Ponceau technique, we found cells which stained more intensely in groups exposed to thiamethoxam. The digestive and regenerative cells of the midgut from exposed bees also showed morphological and histochemical alterations, like cytoplasm vacuolization, increased apocrine secretion and increased cell elimination. Thus, intoxication with a sublethal doses of thiamethoxam can cause impairment in the brain and midgut of AHB and contribute to the honeybee lifespan reduction. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1122–1133, 2014.     

BDE-154 Induces Mitochondrial Permeability Transition and Impairs Mitochondrial Bioenergetics

Brominated flame retardants are used in various consumer goods to make these materials difficult to burn. Polybrominated diphenyl ethers (PBDE), which are representative of this class of retardants, consist of two benzene rings linked by an oxygen atom, and contain between 1 and 10 bromine atoms in their chemical structure, with the possibility of up to 209 different congeners. Among these congeners, BDE-154 (hexa-BDE) is persistent in the environment and easy to detect in the biota, but no apparent information regarding the mechanism underlying action and toxicity is available. Mitochondria, as the main energy-producing organelles, play an important role in the maintenance of various cellular functions. Therefore, mitochondria were used in the present study as an experimental model to determine the effects of BDE-154 congener at concentrations ranging from 0.1 μM to 50 μM. Our results demonstrated that BDE-154 interacts with the mitochondrial membrane, preferably by inserting into the hydrophobic core of the mitochondrial membrane, which partially inhibits respiration, dissipates Δψ, and permeabilizes the inner mitochondrial membrane to deplete ATP. These effects are more pronounced at concentrations equal to or higher than 10 μM. Results also showed that BDE-154 did not induce reactive oxygen species (ROS) accumulation within the mitochondria, indicating the absence of oxidative stress. Therefore, BDE-154 impairs mitochondrial bioenergetics and permeabilizes the mitochondrial membrane, potentially leading to cell death but not via mechanisms involving oxidative stress.     

Regulatory authorities and orthopaedic clinical trials on expanded mesenchymal stem cells

Skeletal injuries requiring bone augmentation techniques are increasing in the context of avoiding or treating difficult cases with bone defects, bone healing problems, and bone regeneration limitations. Musculoskeletal severe trauma, osteoporosis-related fractures, and conditions where bone defect, bone collapse or insufficient bone regeneration occur are prone to disability and serious complications. Bone cell therapy has emerged as a promising technique to augment and promote bone regeneration. Interest in the orthopaedic community is considerable, although many aspects related to the research of this technique in specific indications may be insufficiently recognised by many orthopaedic surgeons. Clinical trials are the ultimate research in real patients that may confirm or refute the value of this new therapy. However, before launching the required trials in bone cell therapy towards bone regeneration, preclinical data is needed with the cell product to be implanted in patients to ensure safety and efficacy. These preclinical studies support the end-points that need to be evaluated in clinical trials. Orthopaedic surgeons are the ultimate players that, through their research, would confirm in clinical trials the benefit of bone cell therapies. To further foster this research, the pathway to eventually obtain authorisation from the National Competent Authorities and Research Ethics Committees under the European regulation is reviewed, and the experience of the REBORNE European project offers information and important clues about the current Voluntary Harmonization Procedure and other opportunities that need to be considered by surgeons and researchers on the topic.     

Biocompatibility of Ricinus communis polymer with addition of calcium carbonate compared to titanium. Experimental study in guinea pigs

Objective

The aim of the present investigation was to determine whether the difference in inflammatory tissue reaction between the Riccinus communis (castor) polymer with calcium carbonate and the titanium implant is statistically significant.

Methods

Thirty-two Cavia porcellus were allocated into four groups of eight animals each. We implanted the two types of materials in the retroperitoneal space of all the animals. They were euthanized at 7, 20, 30 and 40 days after surgery, and an histological study of the samples was conducted.

Results

All implants showed characteristics of chronic inflammation regardless of the material and timepoint of evaluation. There was no statistically significant difference between Pm+CaCO₃ and Ti with regard to the presence of granulation tissue, tissue congestion, histiocytes, lymphocytes, neutrophils, giant cells, and fibrosis (P> 0.05).

Conclusion

The castor oil polymer plus calcium carbonate implant was not statistically different from the titanium implant regarding inflammatory tissue reaction.     

Effects of LED phototherapy on relative wound contraction and reepithelialization during tissue repair in hypothyroid rats: morphometric and histological study

The aim of this study was to assess morphometrically and histologically, the effects of light-emitting diode (LED) (λ630?±?20 nm) phototherapy on reepithelialization and wound contraction during tissue repair in hypothyroid rats. Thyroid hormone deficiency has been associated with disorders of tissue repair. LED phototherapy has been studied using several healing models, but their usefulness in the improvement of hypothyroidism wound healing remains unknown. Under general anesthesia, a standard surgical wound (1 cm²) was produced on the dorsum of 48 male Wistar rats divided into four groups of 12 animals each: EC—control euthyroid, ED—euthyroid + LED, HC—control hypothyroid, and HD—Hypothyroid + LED. The irradiation started immediately after surgery and was repeated every other day for 7 and 14 days. Photographs of the wound were taken at the day of the surgical procedure and on days 8 and 15 after surgery, when animals’ deaths occurred. The specimens were removed, routinely processed, and stained with hematoxylin/eosin. Seven days after the surgery, it was possible to observe statistically significant reductions in the wound area of the irradiated euthyroid group, in comparison to hypothyroid group, irradiated and non-irradiated (ANOVA, p?<?0.05). The reepithelialization was significantly higher in the euthyroid and hypothyroid groups irradiated with LED than in the non-irradiated groups (Fisher’s test, p?<?0.05). No significant difference was found in the experimental period of 14 days among the groups. The hypothyroidism delayed wound healing and the LED phototherapy, at these specific parameters, improved the process of reepithelialization in the presence of hypothyroidism.     

Lung ultrasound during hemodialysis: the role in the assessment of volume status

Objective

Fluid balance is important in patients undergoing hemodialysis. “Dry” weight is usually estimated clinically, and also, bioimpedance is considered reliable. Ultrasonography of inferior vena cava (IVC) estimates central venous pressure, and lung ultrasound evaluates extravascular (counting B-lines artifact) lung water. Our study was aimed to clarify their usefulness in the assessment of volume status during hemodialysis.

Methods

A total of 71 consecutive patients undergoing hemodialysis underwent lung and IVC ultrasound and bioimpedance spectroscopy immediately before and after dialysis.

Results

There was a significant reduction in the number of B-lines (3.13 vs 1.41) and in IVC diameters (end-expiratory diameter 1.71 vs 1.37; end-inspiratory diameter 1.19 vs 0.95) during dialysis. The reduction in B-lines correlated with weight reduction during dialysis (p 0.007); none of the parameters concerning the IVC correlated with fluid removal. At the end of the dialysis session, the total number of B-lines correlated with bioimpedance residual weight (p 0.002).

Discussion

The reduction in B-lines correlated with fluid loss due to hemodialysis, despite the small pre-dialysis number, confirming that lung ultrasound can identify even modest variations in extravascular lung water. IVC ultrasound, which reflects the intravascular filling grade, might not be sensitive enough to detect rapid volume decrease. Clinically estimated dry weight had a poor correlation with both bioimpedance and ultrasound techniques. Post-dialysis B-lines number correlates with residual weight assessed with bioimpedance, suggesting a role for ultrasound in managing hemodialysis patients.