MRI of transplanted pancreatic islets.

A promising treatment method for type 1 diabetes mellitus is transplantation of pancreatic islets containing beta-cells. The aim of this study was to develop an MR technique to monitor the distribution and fate of transplanted pancreatic islets in an animal model. Twenty-five hundred purified and magnetically labeled islets were transplanted through the portal vein into the liver of experimental rats. The animals were scanned using a MR 4.7-T scanner. The labeled pancreatic islets were clearly visualized in the liver in both diabetic and healthy rats as hypointense areas on T2*-weighted MR images during the entire measurement period. Transmission electron microscopy confirmed the presence of iron-oxide nanoparticles inside the cells of the pancreatic islets. A significant decrease in blood glucose levels in diabetic rats was observed; normal glycemia was reached 1 week after transplantation. This study, therefore, represents a promising step toward possible clinical application in human medicine.     

Solute Absorption from the Airways of the Isolated Rat Lung. IV. Mechanisms of Absorption of Fluorophore-Labeled Poly-α,β-[N(2-Hydroxyethyl)-DL-Aspartamide]

The pulmonary absorption kinetics of a single molecular weight distribution (MWD) of fluorophore-labeled poly-,-[N(2-hydroxyethyl)-DL-aspartamide] (F-PHEA), a hydrophilic and biocompatible synthetic polypeptide, were studied in the isolated, perfused rat lung (iprl) as functions of administered polymer concentration, dose, vehicle, and presence and absence of fluorophore. The MWD was characterized before and after absorption by measurement of weight- and number-averaged molecular weights (M _wand M _n, respectively) using high-performance gel-permeation chromatography. Values for M _w and M _n were 8.6 and 5.3 kD before, and 6.7 and 4.7 kD after, absorption into the perfusate; there was no significant metabolism and the MWD of the absorbed polymer was independent of both dose and sampling time over a 3-hr period. F-PHEA failed to show any evidence of aggregation in solution or changes in dose distribution within the airways as functions of increasing polymer concentration and dose. A concentration ranging study indicated the presence of a saturable, carrier-mediated transport process for F-PHEA with a maximum absorption rate, V _max, of approximately 180 µg or 0.027 µmol/hr. Coadministration of fluorophore-free PHEA was capable of depressing the absorption of F-PHEA. The transport process for F-PHEA appeared to have a molecular weight limit of about 7 kD for this hydrophilic polymer.     

Targeting the ERAD pathway via inhibition of signal peptide peptidase for antiparasitic therapeutic design

Early secretory and endoplasmic reticulum (ER)-localized proteins that are terminally misfolded or misassembled are degraded by a ubiquitin- and proteasome-mediated process known as ER-associated degradation (ERAD). Protozoan pathogens, including the causative agents of malaria, toxoplasmosis, trypanosomiasis, and leishmaniasis, contain a minimal ERAD network relative to higher eukaryotic cells, and, because of this, we observe that the malaria parasite Plasmodium falciparum is highly sensitive to the inhibition of components of this protein quality control system. Inhibitors that specifically target a putative protease component of ERAD, signal peptide peptidase (SPP), have high selectivity and potency for P. falciparum. By using a variety of methodologies, we validate that SPP inhibitors target P. falciparum SPP in parasites, disrupt the protein’s ability to facilitate degradation of unstable proteins, and inhibit its proteolytic activity. These compounds also show low nanomolar activity against liver-stage malaria parasites and are also equipotent against a panel of pathogenic protozoan parasites. Collectively, these data suggest ER quality control as a vulnerability of protozoan parasites, and that SPP inhibition may represent a suitable transmission blocking antimalarial strategy and potential pan-protozoan drug target.     

COVID19 infection in a patient with paroxysmal nocturnal hemoglobinuria: A case report

Introduction:Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired, life-threatening hemopoietic stem cell disorder characterized by the triad of hemolytic anemia, thrombosis, and impaired bone marrow function. Evidence suggests that severe outcomes in COVID19 infection are attributed to the excessive activation of the complement cascade leading to acute lung injury and associated is with an increased prothrombotic state.Patient concerns:A 27-year-old Caucasian man with PNH presented to the Emergency Department of our hospital with acute onset shortness of breath, cough and blood in urine.Diagnosis:The patient was diagnosed with acute hemolytic exacerbation of PNH complicated with moderate COVID19 pneumonia.Outcomes:The patient was initiated with an anticoagulant unfractionated heparin, dexamethasone, and cefuroxime injection. His symptoms quickly resolved, and he was discharged after 5 days.Conclusion:The complement system activation is a critical component in the sequalae of COVID19 infection. Evidence suggests that severe outcomes in COVID19 infection are attributed to the excessive activation of the complement cascade leading to acute lung injury and associated is with an increased prothrombotic state. Notably, C5a concentration was noted to be higher in patients with COVID19 infection. The use of complement inhibitors to attenuate immune mediated damage in COVID19 nevertheless represents a very interesting theoretical approach. However, careful consideration as to which patients may benefit will be required and the outcome of clinical trials needed.     

Normalizing Glutamine Concentration Causes Mitochondrial Uncoupling in an In Vitro Model of Human Skeletal Muscle

Background: Glutamine has been considered essential for rapidly dividing cells, but its effect on mitochondrial function is unknown. Materials and Methods: Human myoblasts were isolated from skeletal muscle biopsy samples (n = 9) and exposed for 20 days to 6 different glutamine concentrations (0, 100, 200, 300, 500, and 5000 µM). Cells were trypsinized and manually counted every 5 days. Seven days before the end of exposure, half of these cells were allowed to differentiate to myotubes. Afterward, energy metabolism in both myotubes and myoblasts was assessed by extracellular flux analysis (Seahorse Biosciences, Billerica, MA). The protocol for myoblasts was optimized in preliminary experiments. To account for different mitochondrial density or cell count, data were normalized to citrate synthase activity. Results: Fastest myoblast proliferation was observed at 300 µM glutamine, with a significant reduction at 0 and 100 µM. Glutamine did not influence basal oxygen consumption, anaerobic glycolysis or respiratory chain capacity. Glutamine significantly (P = .015) influenced the leak through the inner mitochondrial membrane. Efficiency of respiratory chain was highest at 200–300 µM glutamine (~90% of oxygen used for adenosine triphosphate synthesis). Increased glutamine concentration to 500 or 5000 µM caused mitochondrial uncoupling in myoblasts and myotubes, decreasing the efficiency of the respiratory chain to ~70%. Conclusion: Glutamine concentrations, consistent with moderate clinical hypoglutaminemia (300 µM), bring about an optimal condition of myoblast proliferation and for efficiency of aerobic phosphorylation in an in vitro model of human skeletal muscle. These data support the hypothesis of hypoglutaminemia as an adaptive phenomenon in conditions leading to bioenergetic failure (eg, critical illness).     

Vascular access monitoring: methods and procedures--something to standardize?

The article discusses the issue of suitable parameters (pressures, recirculation and access flow) to assess hemodialysis vascular access quality (VAQ), available methods to measure those parameters and the setup of the entire VAQ surveillance system (VAQS) in a dialysis facility. Special attention is paid to factors which need some standardization to enable evaluation of VAQ trends in an individual as well as comparison of data from different patients and different dialysis facilities. The discussed procedures are documented with the authors' own measurement results and the results of the VAQS implemented in their unit. Both dynamic and static pressures exhibit insufficient sensitivity in detecting stenoses in native arteriovenous fistulas. Access recirculation is a late finding because with its non-zero value dialysis quality is already compromised. Timely and reliable detection of a deteriorating access condition is enabled by access flow (QVA) only. No standardization is needed in extracorporeal blood flow used in QVA evaluation by ultrasonic dilution. Multiple measurements may increase the reliability of thermodilutional measurements and are a must in optodilutional ones. Timing of the measurement during dialysis should be standardized. Measurement frequency should take into account access type, QVA value and access history. Shortened intervals are needed in the immediate post-intervention period with regard to risk of re-stenosis incidence and strongly nonlinear QVA decreases in such cases. A significant shift-over from surgical interventions to balloon angioplasties is to be expected with the introduction of a VAQS, and appropriate measures must be taken to ensure their quick availability.     

Synthesis and Evaluation of Long-Acting D-Penicillamine Derivatives

This study extends the use of two lathyrogens, β-aminopropionitrile (BAPN) and D-penicillamine (DPA) from daily systemic or local-topical administration to long-time acting agents. This was achieved by converting the hydrophilic drugs into lipophilic derivatives. The synthesis of functional derivatives of DPA consisted in esterification with methyl-, hexyl-, or benzyl alcohols in the presence of thionylchloride. The esters formed were hydrochlorides, acidic and soluble in water. During neutralization in vitro or in vivo by tissue fluid, an oily substance is formed that elutes from a hydrogel polymer at a much slower rate than hydroplilic DPA itself. The degree of lipophilicity, measured as a partition coefficient between octanol/water, was highest for hexyl ester and lowest for methyl ester DPA. A single injection of either DPA hexyl ester HCl or 3-hexyl(amino) propionitrile into the full thickness skin incision wound in rats significantly lowered the breaking strength of the wound 12 days after injection, indicating the interference with collagen cross-linking. Both agents injected into the breast adenocarcinoma in Fisher rats significantly inhibited tumor growth without any signs of local or systemic toxicity. We conclude that these lipophilic lathyrogens with prolonged effectiveness are suitable in the treatment of pathologies, consisting of excessively cross-linked or deposited collagen (fibrotic adhesions, strictures, stenosis, and scar contractures) and in the treatment of single, solitary tumors, malignant and benign.     

Coding variants of TLR2 and TLR4 genes do not substantially contribute to prosthetic joint infection

Objective and design

Prosthetic joint infection (PJI) is a severe complication of total joint arthroplasty (TJA). We conducted a genetic association study that investigated whether selected coding variants of the genes for Toll-like receptors (TLR)2 and TLR4 may contribute to genetic susceptibility for PJI.

Subjects and methods

In total, 350 patients with TJA (98 with PJI/252 without PJI), and 189 unrelated healthy Czech individuals without TJA were enrolled in our study. Three missense polymorphisms of the genes encoding for TLR2 (TLR2 R753Q, rs5743708) and TLR4 (TLR4 D299G, rs4986790 and T399I, rs4986791) were genotyped by “TaqMan” assay.

Results

The frequencies of less common variants for the investigated TLR2/TLR4 polymorphisms in healthy individuals were similar to those observed in other Caucasian populations. Importantly, the distribution of TLR2/TLR4 genotype alleles did not differ between the patients with PJI and the control groups of patients with nonseptic prostheses/healthy individuals.

Conclusion

Our data suggest that structural genetic variants of the receptors TLR2 and TLR4 do not substantially affect the risk of prosthetic joint infection.     

Treatment for brain arteriovenous malformation in the 1998–2011 period and review of the literature

Purpose

The results of the treatment of pial AVM provided at our neurosurgical centre are presented. Based on these results and on an overview of literary data on the efficacy and complications of each therapeutic modality, the algorithm of indications, as used at our institution, is presented.

Cohort of patients

The series comprises 195 patients, aged 9 to 87 years and treated in the years 1998–2011. The surgical group consists of 76 patients; of these, 49 patients solely received endovascular treatment, 25 were consulted and referred directly to the radiosurgical unit, and the remaining 45 were recommended to abide by the strategy of “watch and wait”.

Results

In the surgical group, serious complications were 3.9 %, at a 96.1 % therapeutic efficacy. As for AVM treated with purely endovascular methods, serious procedural complications were seen in 4.1 % of patients, with efficacy totalling 32.7 %. One observed patient suffered bleeding, resulting in death. For comparison with literary data for each modality, a survival analysis without haemorrhage following monotherapy for AVM with each particular modality was carried out.

Conclusions

Based on our analysis, we have devised the following algorithm of treatment:

1. We regard surgical treatment as the treatment of choice for AVM of Spetzler-Martin (S-M) grades I and II, and only for those grade III cases that are surgically accessible.
2. Endovascular intervention should mainly be used for preoperative embolisation, as a curative procedure for lower-grade AVM in patients with comorbidities, and as palliation only for higher-grade cases.
3. Stereotactic irradiation with Leksell Gamma Knife (LGK) is advisable, mainly for poorly accessible, deep-seated grade-III AV malformations. In the case of lower grades, the final decision is left to the properly informed patient.
4. Observation should be used as the method of choice in AVM of grades IV and V, where active therapy carries greater risk than the natural course of the disease.