Coexistence of tetragonal and cubic phase induced complex magnetic behaviour in CoMn2O4nanoparticles.

CoMn2O4, known for its extensive range of applications, has been subject to limited investigations regarding its structure dependent magnetic properties. Here, we have examined the structure dependent magnetic properties of CoMn2O4nanoparticles synthesized through a facile coprecipitation technique and are characterized using x-ray diffractometer, x-ray photoelectron spectroscopy (XPS), RAMAN spectroscopy, transmission electron microscopy and magnetic measurements. Rietveld refinement of the x-ray diffraction pattern reveals the coexistence of 91.84% of tetragonal and 8.16% of cubic phase. The cation distribution for tetragonal and cubic phases are (Co0.94Mn0.06)[Co0.06Mn1.94]O4and (Co0.04Mn0.96)[Co0.96Mn1.04]O4, respectively. While Raman spectra and selected area electron diffraction pattern confirm the spinel structure, both +2 and +3 oxidation states for Co and Mn confirmed by XPS further corroborate the cation distribution. Magnetic measurement shows two magnetic transitions, Tc1at 165 K and Tc2at 93 K corresponding to paramagnetic to a lower magnetically ordered ferrimagnetic state followed by a higher magnetically ordered ferrimagnetic state, respectively. While Tc1is attributed to the cubic phase having inverse spinel structure, Tc2corresponds to the tetragonal phase with normal spinel. In contrast to general temperature dependentHCobserved in ferrimagnetic material, an unusual temperature dependentHCwith high spontaneous exchange bias of 2.971 kOe and conventional exchange bias of 3.316 kOe at 50 K are observed. Interestingly, a high vertical magnetization shift (VMS) of 2.5 emu g-1is observed at 5 K, attributed to the Yafet-Kittel spin structure of Mn3+in the octahedral site. Such unusual results are discussed on the basis of competition between the non-collinear triangular spin canting configuration of Mn3+cations of octahedral sites and collinear spins of tetrahedral site. The observed VMS has the potential to revolutionize the future of ultrahigh density magnetic recording technology.

Drug kinetics and antimicrobial properties of quaternary bioactive glasses 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO); an in-vitro study.

Bioactive glasses have recently been attracted to meet the challenge in bone tissue regeneration, repair, healing, dental implants, etc. Among the conventional bio-glasses, a novel quaternary mesoporous nano bio-glass with composition 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO) (x = 0, 1.6, 2.4, 4 and 8 mol%) employing Stober's method has been explored for examining the above potential application through in-vitro SBF assay, MTT assay, antimicrobial activity and drug loading and release ability. With increasing the MgO concentration up to 4 mol%, from in-vitro SBF assay, we observe that HAp layer develops on the surface of the nBGs confirmed from XRD, FTIR and FESEM. MTT assay using MG-63 cells confirms the biocompatibility of the nBGs having cell viability >225 % for MGO_4 after 72 h which is more than the clinically used 45S5 bio-glass. We have observed cell viability of >125 % even after 168 h. Moreover, MGO_4 is found to restrict the growth of E. coli by 65 % while S. aureus by 75 %, confirming the antimicrobial activity. Despite an increase in the concentration of magnesium, nBGs are found to be non-toxic towards the RBCs up to 4 mol% of MgO while for 8 %, the hemolysis percentage is >6 % which is toxic. Being confirmed MGO_4 nBG as a bioactive material, various concentrations of drug (Dexamethasone (DEX)) loading and release kinetics are examined. We show that 80 % of loading in case of 10 mg-ml-1 and 70 % of cumulative release in 100 h. The mesoporous structure of MGO_4 having an average pore diameter of 5 nm and surface area of 216 m2 g-1 confirmed from BET supports the loading and release kinetics. We conclude that the quaternary MGO_4 nBG may be employed effectively for bone tissue regeneration due to its high biocompatibility, excellent in-vitro cell viability, antimicrobial response and protracted drug release.

Flap management of groin wounds following vascular procedures: A review of 270 flaps for vascular salvage.

BACKGROUND: Groin dehiscence following vascular procedures results in morbidity for patients with peripheral vascular disease. Controversy exists around the indications for flap coverage. We present an institutional experience with flap reconstruction of groin wounds after vascular procedures to identify predictors of beneficial outcomes. PATIENTS AND METHODS: A retrospective review of patients who had flap coverage for infected/nonhealing groin wounds following a vascular procedure between 1998 and 2021 was performed. Demographics and clinical characteristics, including flap and vascular graft type, were collected along with major complications. Univariate and multivariable logistic regression analyses were performed to assess the associations between procedures and major complications. RESULTS: A total of 270 flaps were transferred to 237 patients. Thirty-three patients had bilateral wounds. The mean age and BMI were 67 ± 11 years and 27.9 ± 6.3 kg/m2, respectively. Flaps included rectus femoris (n = 142), sartorius (n = 118), rectus abdominis (n = 7), and gracilis (n = 3). Covered vascular grafts included prosthetic materials (n = 200) and autografts (n = 70). The median length of hospital stay after surgery was 10 days (interquartile range=12), and the mean follow-up was 29.1 ± 39.2 months. The major complication rate was 38.5% with wound infection being the most common. Flaps successfully prevented the infection-related removal of the grafts in 98.9% of cases. Multivariable analysis revealed no significant associations between variables and having a major complication. CONCLUSIONS: Flap coverage of the inguinal vessels can be performed safely with favorable limb salvage. Wound complications were high, but graft salvage was excellent. Rectus femoris and sartorius muscle flaps were the most common flaps, yielding comparable outcomes.

Liposuction to improve vascular access in hemodialysis patients with arteriovenous fistulas.

Background: Arteriovenous fistulas (AVFs) are indispensable in the care of patients with end-stage renal disease requiring hemodialysis. Obesity is a common comorbidity in hemodialysis patients, often making AVF cannulation technically challenging. Liposuction can be performed for superficialization of the AVF without the need for an open superficialization procedure. The aim of the present study was to evaluate the outcomes of liposuction to improve AVF access for hemodialysis. Methods: We performed a retrospective medical record review of patients who had undergone liposuction over an AVF at our institution from January 2000 to September 2021. Data were collected on the demographics, medical comorbidities, AVF site and depth, AVF diameter and flow, operative details, surgical complications, and follow-up. Results: A total of 19 patients had been referred by the hemodialysis clinic for liposuction. Their mean age was 55.5 years, and their mean body mass index was 39.5 kg/m2. Either liposuction alone or liposuction combined with minimal access direct lipectomy was performed to superficialize the AVF. All procedures were performed secondarily, after prior creation of the AVF. Of the 19 patients, 18 had had an upper AVF and 1 had had a lower extremity AVF graft. Of the 19 patients, 12 (63%) had proceeded to hemodialysis after one liposuction. The mean time to cannulation for 10 of these 12 patients was 52.1 ± 25.6 days. Two of the 12 patients were excluded from the mean calculation to prevent skewing from their prolonged time to requiring dialysis initiation. Of the 19 patients, 2 had required additional liposuction sessions, and 1 had required AVF intervention after the first liposuction attempt before achieving successful cannulation. Four patients (21%) had had unsuccessful cannulation despite additional liposuction or AVF interventions owing to AVF stenosis or thrombosis. Overall, 15 of the 19 patients (79%) had successfully proceeded to dialysis in the same extremity. The mean access depth had decreased from 1.75 cm before liposuction to 0.93 cm after liposuction. The mean volume of fat removed was 92.3 cm3. Of the 16 patients with prior dialysis catheters, 11 were eventually removed after surgery once the vascular site was accessible. The body mass index correlated positively with the interval to the first successful cannulation (r = 0.5881; P < .05). The surgical complications included two cases of cellulitis treated with oral antibiotics. The mean follow-up time was 38.3 months. Conclusions: Our results have shown that liposuction can be performed safely in obese patients requiring hemodialysis and was successful in improved AVF access for 15 of the 19 patients (79%) in our cohort. Larger studies are needed to compare the outcomes of this technique with those of open superficialization.

Lipoblastoma of the extremities.

BACKGROUND: Lipoblastoma is a rare benign tumor of infancy and childhood, with similar radiographic imaging findings as malignant liposarcoma. Therefore, it is crucial to distinguish through other diagnostics and clinical features. We present our experience with the diagnosis and clinical management of this entity. METHODS: A retrospective chart review was performed to identify children treated for lipoblastoma at our institution over a 30-year period. Charts were evaluated for diagnostic methods, treatment, and recurrence risk. RESULTS: A total of 9 males and 3 females were identified. The age at diagnosis ranged from 8 months to 44 years. Imaging modalities employed included ultrasound (N = 5), MRI (N = 12), X-ray (N = 8), and CT (N = 3). The tumor location was reported in the lower extremity (N = 8) and upper extremity (N = 4). The tumor size ranged from 1.7 to 18 cm (mean=7.08 cm). All patients underwent complete resection. Available pathology reports noted masses featuring mature adipocytes (N = 1), fibrous septa (N = 2), focal myxoid changes (N = 1), and spindle cells (N = 2). Nine patients underwent chromosomal analysis, which demonstrated five chromosome 8 abnormalities. No recurrences were reported. Three patients had follow-up imaging, and 11 had follow-up visits between 2 weeks to 15 years. CONCLUSION: Lipoblastoma is an uncommon childhood neoplasm of embryonic white fat that can also be present in adolescence and adulthood. Imaging, especially MRI, is helpful in limiting the differential diagnosis, but definitive diagnosis requires tissue biopsy, which should be obtained with core biopsy rather than fine needle aspiration. Surgical resection is curative with few complications. We do not recommend routine monitoring as recurrence is unlikely.

Long-term survival analysis of free flap reconstruction in patients with collagen vascular disorders.

BACKGROUND: Collagen vascular disorders (CVD) are inflammatory diseases that can affect the blood vessels and soft tissues. Patients with CVD are often immunosuppressed, prone to hyper-coagulation, and represent a challenging patient cohort for free tissue transfer. METHODS: A retrospective review of patients with CVD who underwent free flap reconstructions from 2000-2020 was performed at our institution. Inclusion criteria were patients 18 years old or older with the clinical diagnosis of CVD, including rheumatoid arthritis, Raynaud phenomenon, systemic lupus erythematosus, scleroderma, and sarcoidosis. A time-to-event analysis was performed to identify predictors of surgical complications. RESULTS: A total of 78 patients and 96 free flaps were included. The most common CVD were rheumatoid arthritis (n=36) and Raynaud's phenomenon (n=9). Type of flap included abdominal-based flap (26%), trunk-based flaps (32.3%), and extremity-based flaps (19.8%). The mean age was 56.7±14.6 years, and the mean BMI was 27.5±5.9 kg/m2. Antibody positivity was present in 25.6% of patients; 59% were on chronic steroids, 6.4% were on chronic anticoagulation, 35.9% had radiation therapy, and 29.5% had chemotherapy. Nine percent of patients had a history of prior flap loss, and 11.5% had a history of DVT or arterial thrombosis. The flap loss rate was 3.8%. Steroid treatment was associated with an increased risk of major complications after adjusting for the type of flap HR 2.5(1.3-4.9), p= 0.01. Specifically associated with a higher risk of cellulitis, OR 5.1 (1.1-24.5), p=0.02, and abscess, OR 5.7 (1.2-27.1), p=0.01. CONCLUSION: Free flap reconstruction can be safely performed in patients with CVD. Perioperative optimization of steroids is important to promote wound healing and stabilize disease activity.