Do large parathyroid adenomas increase the risk of severe hypercalcemia?

<b><br>Introduction:</b> Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma (PA). Rare variants of PA, weighing >2.0-3.5 g are called "large" or "giant" adenomas and account for about 1.5% of all PA.</br> <b><br>Aim:</b> The aim of this study was to compare normal-sized and large parathyroid lesions identifying risk factors for severe hypercalcemia.</br> <b><br>Materials and methods:</b> 27 patients with PHPT and parathyroid lesion ≥2.0 cm3 (study group) were compared with 73 patients with PHPT and lesion < 2.0 cm³ (control group). In both groups, the majority were women (81.5% - study group, 90.5% - control group, gender ratios 4.4:9.1, respectively). The patients were examined preoperatively and postoperatively: PTH, creatine, calcium, and phosphate serum and urine concentrations, and calcidiol serum levels were assessed. Preoperative ultrasonography (US) was performed.</br> <b><br>Results:</b> Patients with larger parathyroid lesions had signifficantly higher PTH and calcium serum concentrations and lower serum phosphate and calcidiol concentrations. There were no statistically significant differences in the concentration of creatine in serum and urine, calciuria, or tubular reabsorption of phosphorus (TRP). US relatively underestimated the parathyroid volume by about 0.3-0.4 mL (10% in larger lesions and 43% in smaller ones).</br> <b><br>Conclusions:</b> Due to higher PTH and calcium levels, larger parathyroid adenomas may constitute a higher risk of severe hypercalcemia. In general, US underestimated the parathyroid volume.</br>.

Successful Endovascular Microembolization for Post-Traumatic High-Flow Priapism: A Case Report.

BACKGROUND High-flow (non-ischemic) priapism is a rare urological condition usually related to blind trauma to the penis or perineum causing an arterial-lacunar fistula. It can be treated conservatively, but in some cases when conservative treatment fails, the interventional approach is indicated. In the past, only surgical treatment was available, which was associated with a significant risk of complications. Endovascular techniques use a novel approach and offer clinical benefits for the patient. CASE REPORT A 51-year-old man was admitted to the hospital after referral from the urology department with high-flow priapism related to blunt trauma. Angio-computed tomography showed extravasation of contrast medium to the corpus cavernosum, and angiography revealed a fistula between the distal segment of the left internal pudendal artery and corpora cavernosa. A successful endovascular microembolization of the arterial-lacunar fistula with the use of microcoils was performed. The postprocedural period was uneventful and the patient was discharged. Despite incomplete angiographic follow-up at 6 months, the initial symptoms were fully resolved with the absence of any erectile dysfunction and no recurrence of priapism occurred. CONCLUSIONS Post-traumatic high-flow priapism can be safely and effectively treated by endovascular means. Microembolization has proven to be successful and beneficial to preserve sexual functions.

Anemia in Patients After Stem Cell Transplantation and in Kidney Transplant Recipients.

Hematopoietic stem cell transplant (HSCT) is the treatment of choice in various hematologic diseases, and kidney transplantation (KTx) is the best therapy for end-stage kidney disease. Chronic kidney disease (CKD) occurs relatively often after both types of transplantations. Anemia after both HSCT and KTx may be due to CKD and other reasons. This study aimed to assess the prevalence of anemia to CKD in 156 prevalent patients after HSCT and 80 after KTx. According to the World Health Organization's definition (hemoglobin <13 g/dL for men and <12 g/dL for women), the prevalence of anemia in the studied cohort after HSCT was 13% in women and 35% in men and for those after KTx, it was29% in men and 11%. Anemia in KTx was found in 46% of patients, whereas CKD was present in 53%. After HSCT, anemia was associated with CKD in 56% of women and 17% of men. In KTx, anemia and CKD was diagnosed in 21% of patients. Patients with anemia after KTx had significantly lower glomerular filtration rate (GFR), hemoglobin, and significantly higher creatinine levels. Age was related to the estimated GFR (eGFR; r = -0.39, P < .001) in patients who underwent HSCT and had anemia. In patients without anemia, age was negatively related to eGFR (r = -0.56, P < .001) and the hemoglobin-to-platelet count (r = 0.62, P < .001). In KTx, hemoglobin was related to eGFR (r = 0.35, P < .001), and age was related to eGFR (r = -0.20, P < .05). The type of induction therapy immunosuppressive regimen (anti-thymocyte globulin vs basiliximab vs no induction) did not affect the prevalence of anemia in the KTx population studied. Anemia is relatively common in CKD after HSCT. In both CKD and coexistent anemia, nephrology referral is to be considered to optimize therapy, including nephroprotection.

Left-Sided Pneumothorax in a Potential Kidney Transplant Recipient-A Surprise in the Surgical Ward: Case Report.

BACKGROUND: The risk of morbidity and mortality in the group of people qualified for kidney transplantation is high. Although currently, the qualification for kidney transplantation is very extensive and detailed, the final examination and assessment at the transplant center is crucial for the success of the transplantation. CASE REPORT: A 50-year-old woman with end-stage kidney disease was admitted to the Department of General, Vascular, and Transplant Surgery on July 21, 2023, for kidney transplantation. A month earlier, she had undergone surgery to create an arteriovenous fistula on the left forearm. The regional anesthesia was performed. Apart from temporary pain and cough, the postoperative course was uncomplicated. Upon admission to the Department, the patient was in good general condition, and only a dry cough was noted during the physical examination. Chest X-ray revealed pneumothorax on the left side with partial lung atelectasis. The patient was temporarily disqualified from kidney transplantation and the pneumothorax was cured. She is currently on the active list waiting for a kidney transplant. CONCLUSIONS: The analysis of the above case emphasizes the importance of a physical examination and final qualification at the transplant center. Detailed examination and evaluation at the above center can improve patients' quality of life and survival.

Outcomes of Combined Liver-Kidney Transplantation - Single Center Experience.

BACKGROUND: There is continuous growth of combined liver-kidney transplantation (CLKTx) numbers with remarkable outcomes, especially among patient with liver cirrhosis and end-stage renal disease. The aim was to present a single center experience. METHODS: Twenty patients (9 males) with a mean age of 48 (range: 20-62) years underwent CLKTx from 2005 to 2022. Indications were polycystic liver and kidney diseases (ADPKD) in 12 cases, cirrhosis due to hepatitis (4 patients), and 1 case of amyloidosis, alcoholic liver disease, nonalcoholic steatosis, and congenital hepatic fibrosis with concomitant glomerulonephritis. After hepatectomy, half of the patients had orthotopic liver transplantation with piggy-back technique, and the other had conventional technique. All but 1 recipient had biliary end-to-end anastomosis. 3 patients had preemptive kidney graft transplantation. 4 underwent simultaneous right-side nephrectomy due to volume of the right kidney. Kidney was transplanted from the separate incision after abdominal closure with typical anastomoses. Tacrolimus, mycophenolate mofetile, basiliximab, and steroids were applied for all recipients. RESULTS: Mean follow-up was 57.7 ± 54 months. No primary non-function of the grafts occurred. Delayed kidney graft function (DGF) occurred in 8 patients. Three-month, 1-year, and 5-year cumulative survival rates were: 90%, 80%, and 72% respectively. None of the patients required retransplantation, and 1 recipient returned to hemodialysis 19 months after transplantation. Preemptive kidney transplantation and simultaneous right-side nephrectomy were not significant for DGF and recipient survival. No deaths within the first year occurred in piggy-back technique. CONCLUSIONS: CLKTx is safe and effective in the treatment of both liver and kidney failure.

Effect of Pretransplant Dialysis Method and Vintage on Early Clinical Outcomes of Kidney Transplantation.

BACKGROUND: Pre-transplantation dialysis duration and modality may affect patients' long-term (mortality and graft failure) and short-term (delayed graft function) outcomes after kidney transplantation. We aimed to assess the impact of the method and duration of dialysis therapy on the graft function in the first 6 months post-transplant. METHODS: The analysis included 122 kidney transplant patients (109 from a deceased donor and 13 from a living donor). Before transplantation, 91 were on hemodialysis (HD), 19 were on peritoneal dialysis (PD), and 9 received preemptive transplants. The incidence of delayed graft function (DGF) and creatinine levels at discharge and 6 months after transplantation were assessed. RESULTS: PD and HD patients did not differ in age, number of mismatches, and cold ischemia time (CIT), but they had a significantly shorter dialysis vintage (18.3 ± 25.7 vs 39.6 ± 34.3 months, P = .01) and a lower incidence of DGF (5% vs 37%, P = .006). The duration of hospitalization and creatinine concentration at discharge and after 6 months were similar. Preemptively transplanted patients had a significantly shorter CIT (ND vs DO - 576 ± 362 vs 1113 ± 574, P = .01; ND vs HD - 576 ± 362 vs 1025 ± 585 minutes, P = .01). DGF did not occur in any of the patients transplanted preemptively. They had slightly shorter hospitalization times and, compared to HD, better graft function at discharge. After 6 months, creatinine levels were comparable to HD and PD. Patients dialyzed for less than 12 months, regardless of the method, had a lower incidence of DGF. CONCLUSIONS: Peritoneal dialysis and a short duration of pre-transplant dialysis may improve the early results of kidney transplantation.

Recurrence of Glomerulonephritis After Kidney Transplantation - Experience of One Center from 2020 to 2023.

BACKGROUND: Glomerulonephritis (GN) after kidney transplantation is a common problem. Many of them are recurrences of the primary disease in the transplanted kidney. The course and prognosis of individual types of glomerulonephritis (GN) are very different and their appearance may worsen the graft survival. World statistics show significant discrepancies regarding the incidence of GN recurrence depending on the adopted protocol (protocolar biopsy or due to symptoms). We analyzed the transplanted kidney biopsy results that are performed only in symptomatic patients. METHODS: A group of 125 patients transplanted and treated in one medical center were observed. In this group, in 32 patients, the primary kidney disease was GN, confirmed by kidney biopsy before transplantation. Twenty three kidney biopsies were performed; in 8, cases the primary disease was GN. The indication for biopsy were hematuria and/or proteinuria and/or graft failure. RESULTS: We diagnosed 5 cases of GN, including 4 cases of GN recurrence (12.5% in whole GN group, 50% in symptomatic GN group). In the relapse group, there was 1 case of IgA nephropathy (the earliest recurrence 1 month after transplantation), 1 case of focal segmental glomerulosclerosis, 1 case of membranous nephropathy, and 1 case of lupus nephritis (the latest recurrence 1 year and 4 months after transplantation). CONCLUSIONS: Our observation showed a high percentage of GN recurrences in symptomatic patients. This indicates the need to specify data regarding the diagnosis of recurrence depending on the adopted research method (protocolar or due to symptoms biopsy) to know which patients should be treated.

Comparison of Fine-Needle Aspiration Cytopathology with Histopathological Examination of the Thyroid Gland in Patients Undergoing Elective Thyroid Surgery: Do We Still Need Fine-Needle Aspiration Cytopathology?

BACKGROUND: The thyroid gland is responsible for various functions, but it is susceptible to pathologies. The gold standard for preliminarily diagnosing thyroid abnormalities is fine-needle aspiration cytology (FNAC), although it has some limitations; thus, postoperative histopathological examination confirms the diagnosis. The aim of the present study was to compare preoperative FNAC results with postoperative histopathological examination. METHODS: This study is a retrospective study based on FNAC and postoperative histopathology examination, which were compared and analyzed. RESULTS: This study included 344 patients between 18 and 86 years old (mean age: 53.06 ± 13.89), comprising 274 females and 70 males (mean ages 52.72 ± 13.86 and 54.39 ± 14.05, respectively) with a 3.9:1 female-to-male ratio. Statistical significance between the FNAC and histopathology results was observed (p = 0.0000), and 86 (25.00%) patients were found to have been diagnosed incorrectly based on FNAC. The sensitivity of FNAC was 92.31%, and its specificity was 82.08%, with positive and negative predictive values of 68.57% and 96.08%, respectively. CONCLUSIONS: Due to many factors, FNAC may lead to over- or under-diagnosis, increasing the chances of complications associated with the selected treatment. However, we do not have any other more accurate tools; therefore, FNAC should still remain as the gold standard of preliminary examination.

Impact of Internal Carotid Stenosis Treatment on Cerebral Blood Flow Volume: A Comparative Study between Preoperative and Postoperative Values.

BACKGROUND Among patients with ICA stenosis, there are some cases with elevated, undisrupted, and diminished cerebral blood flow (CBF). The aim of this study was to assess the influence of ICA stenosis treatment on postoperative CBF changes in relation to preoperative CBF values. MATERIAL AND METHODS We qualified 58 patients ≥65 years old (28 males, 30 females, mean age 71.02±6.34 years) for surgical intervention due to symptomatic ≥70% ICA stenosis. In all patients, a flow volume in all extracranial arteries (internal carotid [ICA], external carotid [ECA], and vertebral arteries [VA]) was measured preoperatively and 2-3 days following the surgery. The CBF values were compared with the ones established for a healthy population of the same age. RESULTS Preoperatively, there were 3 subgroups of patients, comparing to healthy population: with elevated CBF - "significant compensation," with undisrupted CBF - "mild compensation," and with diminished CBF - "no compensation." Postoperatively, a significant CBF increase was observed in patients with preoperative "no" and "mild compensation" - 277.18±154.26 ml/min (P=0.0000001) and 221.56±98.8 ml/min (P=0.0000001). In a "significant compensation" group, there was no flow increase observed (CBF change of 2.57±58.5 ml/min, P=0.954) - a redistribution of flow was observed. CONCLUSIONS In patients with lower preoperative CBF values, surgical treatment caused a significant increase in global cerebral inflow, which was more prominent in patients with the lowest preoperative CBF. In patients with high preoperative CBF, surgical treatment resulted in a flow redistribution, but did not cause a CBF increase. Volumetric flow assessment in DUS can predict hemodynamic benefit from surgery in terms of CBF increase.

Rapid Formation and Hybrid Treatment of a Large Superior Mesenteric Artery Aneurysm.

BACKGROUND Superior mesenteric artery (SMA) aneurysms account for about 5.5% of all visceral aneurysms, and are most commonly secondary to infectious causes or dissection. They tend to expand and rupture. Here, we present our successful diagnosis and treatment of a 41-year-old man with asymptomatic coeliac trunk stenosis, in whom the large aneurysm of the branch of the SMA developed in a very short time after conservative treatment of plastron appendicitis. CASE REPORT A 41-year-old man was diagnosed with plastron appendicitis during abdomen ultrasound (US) examination. Following 2 weeks of conservative treatment with intravenous antibiotic therapy, complete resolution of symptoms was obtained and confirmed in the computed tomography (CT) scan, and no other pathologies were diagnosed. Three weeks later, during the US examination, a 33-mm aneurysm of the branch of the SMA was diagnosed. The patient was admitted to the Vascular Surgery Department, where a critical stenosis of the coeliac trunk secondary to the compression by median arcuate ligament and a 33-mm true visceral aneurysm of one of the branches of the SMA were diagnosed. Successful treatment of the aneurysm was performed. Surgical decompression of the coeliac trunk and subsequent elective endovascular embolization of the SMA aneurysm with angioplasty of the coeliac trunk were performed. The postoperative period was uneventful and the patient was released from the hospital and remains asymptomatic. CONCLUSIONS Visceral artery aneurysm can form very quickly. In some of the aneurysms, a combination of open surgical and endovascular methods should be performed.

Evaluation of selected parameters of inflammation, coagulation system, and formation of extracellular neutrophil traps (NETs) in the perioperative period in patients undergoing endovascular treatment of thoracoabdominal aneurysm with a branched device (t-Branch).

Extracellular Neutrophils Traps (NETs) and their formation, known as NETosis, have become pivotal in the pathogenesis of aortic aneurysm development. This study investigates the NETosis markers with the assessment of selected parameters of inflammation and coagulation system in patients with thoracoabdominal aortic aneurysms in the pre-and postop period undergoing t-Branch stent-graft implantation. The study included 20 patients with thoracoabdominal aortic aneurysms. Three markers double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), and citrullinated H3 histones (Cit-H3) were tested at three-time points from patients' blood. The parameters of NETosis, inflammation, and coagulation system were examined in the preoperative period (within 24 h before surgery) and in the postoperative period (on the 3rd and 5th postoperative day). Free-circulating DNA (cfDNA) was isolated from the blood using the MagMAXTM Cell-Free DNA Extraction Kit. Double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) were then quantified using the Qubit dsDNA HS Assay Kit and the Qubit ssDNA Assay Kit. Cit-H3 concentration was determined by enzyme immunoassay ELISA (Cayman). The results revealed the significance of NETs secretion in response to the complex processes after stent-graft implantation. All NET markers increased shortly after surgery, with histones being the first to return to preoperative levels. The lack of normalization of dsDNA and ssDNA levels to preoperative levels by the last postoperative blood collection demonstrates NETs reorganization. The increase in the number of neutrophils was not related to the expansion of postoperative NETosis. The study reveals a new marker of NETosis, ssDNA, that has not been studied so far. The implantation of a stent graft in a patient with TAAA triggers an inflammatory response manifested by an increase in inflammatory parameters. One of the hallmarks of inflammation is the activation of neutrophil extracellular traps.

Ultra-thin lithium aluminate spinel ferrite films with perpendicular magnetic anisotropy and low damping.

Ultra-thin films of low damping ferromagnetic insulators with perpendicular magnetic anisotropy have been identified as critical to advancing spin-based electronics by significantly reducing the threshold for current-induced magnetization switching while enabling new types of hybrid structures or devices. Here, we have developed a new class of ultra-thin spinel structure Li0.5Al1.0Fe1.5O4 (LAFO) films on MgGa2O4 (MGO) substrates with: 1) perpendicular magnetic anisotropy; 2) low magnetic damping and 3) the absence of degraded or magnetic dead layers. These films have been integrated with epitaxial Pt spin source layers to demonstrate record low magnetization switching currents and high spin-orbit torque efficiencies. These LAFO films on MGO thus combine all of the desirable properties of ferromagnetic insulators with perpendicular magnetic anisotropy, opening new possibilities for spin based electronics.

Cystic Parathyroid Adenomas as a Risk Factor for Severe Hypercalcemia.

(1) Background: Parathyroid cystic adenomas (PCA) are rare entities representing only 0.5-1% of parathyroid adenomas, accounting for 1-2% of cases of primary hyperparathyroidism (PHPT). The purpose of this study was to compare classical and functional/secreting cystic parathyroid lesions and identify risk factors for severe hypercalcemia; (2) Methods: A total of 17 patients with PHPT and parathyroid cysts (study group) were compared with the group of 100 patients with hyperparathyroidism caused by adenoma or hyperplasia (control group). In both groups the majority were women (88% vs. 12%, with gender ratio 7, 3:1). The patients were examined preoperatively and postoperatively: PTH, creatine, calcium and phosphate serum and urine concentrations and calcidiol serum levels were assessed; (3) Results: Patients with parathyroid cyst had statistically higher PTH and calcium serum concentration, higher calciuria and lower serum phosphate concentration. There were no statistically significant differences in the concentration of creatine in serum and urine and tubular reabsorption of phosphorus (TRP); (4) Conclusions: Due to higher PTH and calcium levels, cystic parathyroid adenomas could be one of the rare risk factors for severe hypercalcemia and hypercalcemic crisis which can be life threatening.

Can Color Doppler Ultrasound Be Effectively Used as the Follow-Up Modality in Patients Undergoing Splenic Artery Aneurysm Embolization? A Correlational Study between Doppler Ultrasound, Magnetic Resonance Angiography and Digital Subtraction Angiography.

Splenic artery aneurysm (SAAs) rupture is associated with a high mortality rate. Regular surveillance with imaging before and after intervention is crucial to guide best evidence treatment. The following study aimed to determine the efficacy of color Doppler ultrasound imaging (DUS) compared to digital subtraction angiography (DSA) and magnetic resonance angiography (MRA) as a follow-up modality after selective coil embolization of true SAAs. We analyzed data from 20 patients, 15 females (48.1 ± 16.1 years) undergoing selective SAA coil embolization using detachable fibered embolization coils. Imaging using DUS, MRA, and DSA was performed 3 months after the initial embolization or the consequent re-embolization procedure. Primary clinical success, defined as Class I aneurysm occlusion, on 3-month follow-up was seen in 16 (80.0%) patients. DUS had a sensitivity of 94.4% and a specificity of 42.9% when compared to DSA and 92.3% and 30%, respectively, when compared to MRA in identifying Class I aneurysm occlusion. The positive predictive value (PPV) of DUS in identifying the need for re-embolization was 75.0%, while the NPV of DUS in these terms was 90.5%. DUS showed a high sensitivity in detecting aneurysm occlusion and clinical success, simultaneously exhibiting poor specificity. Still, with caution, this follow-up modality could be used for monitoring select low-risk patients after selective embolization of SAAs. DUS could provide a higher cost-to-benefit ratio, enabling more systematic post-procedural follow-up, as it is far more commonly used compared to MRA and non-invasive compared to DSA.

Huge Hematoma as First Manifestation of Adrenocortical Carcinoma: A Case Report.

BACKGROUND Adrenocortical carcinoma (ACC) is a rare malignancy associated with unfavorable prognosis. It is mainly diagnosed in the fifth or sixth decade of life. Symptoms of ACC are associated with hormonal activity, presence of metastases, and size of the tumor. The treatment and prognosis depend on the stage of the disease assessed with the ENSAT staging system. CASE REPORT A 38-year-old White man was admitted to our department from the city hospital due to a huge hematoma of the right adrenal gland (130×100 mm). On admission, the patient's condition was stable, and no active bleeding or other complications were present. Therefore, initially, conservative treatment was performed. The control CT scan showed reduction of the hematoma (90×80 mm). Due to the unknown character of the tumor and the sudden onset of bleeding, the patient was prepared for elective surgery according to the phaeochromocytoma surgery protocol. Following preparation, the patient underwent right-sided adrenalectomy. In the postoperative histopathological examination, adrenocortical carcinoma was diagnosed, which allowed the patient to receive appropriate oncological treatment. CONCLUSIONS There is currently no clear algorithm for the management of adrenal hemorrhage. A hemodynamically unstable patient requires urgent surgical treatment. Patients in good general condition should be prepared for early elective surgery.

Association Between Parafibromin Expression and Presence of Brown Tumors and Jaw Tumors in Patients with Primary Hyperparathyroidism: Series of Cases with Review of the Literature.

BACKGROUND Brown and jaw tumors are rare entities of poorly understood etiology that are regarded as end-stage of bone remodeling in patients with long-lasting and chronic hyperparathyroidism. Jaw tumors are mainly diagnosed in jaw tumors syndrome (HPT-JT syndrome) and are caused by mutation in the CDC73 gene, encoding parafibromin, a tumor suppressing protein. The aim of this work is to present 4 cases of patients in whom the genetic mutation of the CDC73 gene and clinical presentation coexist in an unusual setting that has not yet been described. CASE REPORT We present cases of 4 patients with primary hyperparathyroidism. Three were diagnosed with brown tumors (located in long bones, ribs, iliac, shoulders) and 1 with brown and jaw tumors. Expression of parafibromin in affected parathyroid tissues were analyzed. In patients without positive parafibromin staining, we searched for CDC73 mutation using next-generation sequencing. Parafibromin staining was positive in 1 patient with brown tumors and was negative in 2 individuals with brown tumors and 1 with brown and jaw tumors. CDC73 mutation was detected in two-thirds of patients (60%) with negative staining for parafibromin and brown tumors. MEN1 mutation was found in the patient with brown tumor and positive staining for parafibromin. CONCLUSIONS Patients with hyperparathyroidism and coexistence of brown tumors or jaw tumors might have decreased expression of parafibromin in parathyroid adenoma tissue, which might be caused by CDC73 mutation and suggest a genetic predisposition. Further research on much larger study groups is needed.

Volumetric Flow Assessment in Extracranial Arteries in Patients with 70-99% Internal Carotid Artery Stenosis.

Background: Cerebral blood flow (CBF) can be related to the risk of occurrence of neurological symptoms. Well-developed collateral circulation is a good prognostic factor in patients with cerebrovascular disease. Understanding the mechanisms of collateral circulation may be important in the diagnosis, treatment, and monitoring in this group of patients. The aim of this study covered the assessment of CBF in patients with 70−99% Internal carotid artery (ICA) stenosis, focusing on the circulation pathways and flow volume in extracranial arteries. Materials and methods: 53 patients with 70−99% ICA stenosis (mean age 73.4 ± 7 years old; 17 female, mean age 73.9 ± 7.5 years old; 36 male, mean age 73.2 ± 6.8 years old) were included in the study. In all patients a Doppler ultrasound (DUS) examination, measuring blood flow volume in the internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA), was performed. The cerebral blood flow (CBF) was compared to the previously reported CBF values in the healthy population > 65 years old. Results: Among the study groups three subgroups with flow differences were identified: patients with elevated CBF (significant volumetric flow compensation­26/53, 49%), patients with CBF similar to (mild compensation­17/53, 32%), and patients with CBF lower than (no compensation­10/53, 19%) the healthy, equally aged population. The percentage of patients with significant volumetric flow compensation was the highest in age groups 65−69 years old (62.5%) and >80 years old (60%). In the oldest age group (>80 years old) no patients without flow compensation (0%) were observed. The level of compensation depends on the number of the arteries with compensatory increased flow. In patients with significant volumetric flow compensation, the compensatory increased flow was observed, on average, in 3.31 arteries, in the mild compensation group­in 2.18 arteries, and in the no compensation group only in 1 artery. ICA plays the most important role in the volumetric flow compensation­the increase in the flow volume, in comparison to the reference values, was between 116.7 mL/min and 251.9 mL/min (in the ECA 57.6 mL/min−110.4 mL/min; in the VA 73.9 mL/min−104.9 mL/min). The relative flow increase was highest in the VA: 215−246%, then in the ECA: 163−206%, and finally in the ICA: 148.6−192%. The increased flow was most commonly observed in the VA­57 arteries, in second place in the ECA­42 arteries, and ICA­31 arteries. In patients with unilateral ICA stenosis, the volumetric flow increase was stated more frequently in the ipsilateral ECAs then in the contralateral ones (23 vs. 14). In the VA the opposite tendency was observed (29 contralateral vs. 23 ipsilateral). The ability of volumetric flow compensation decreased significantly with increasing age. Conclusions: Understanding the mechanisms of collateral circulation and their assessment in Doppler ultrasonography may provide a novel and easily accessible tool of identifying and monitoring patients with cerebrovascular disease.

Exploiting the Nanostructural Anisotropy of ß-Ga2O3 to Demonstrate Giant Improvement in Titanium/Gold Ohmic Contacts.

Here we demonstrate a dramatic improvement in Ti/Au ohmic contact performance by utilizing the anisotropic nature of ß-Ga2O3. Under a similar doping concentration, Ti/Au metallization on (100) Ga2O3 shows a specific contact resistivity 5.11 × 10-5 Ω·cm2, while that on (010) Ga2O3 is as high as 3.29 × 10-3 Ω·cm2. Temperature-dependent contact performance and analyses suggest that field emission or thermionic field emission is the dominant charge transport mechanism across the Ti/Au-(100) Ga2O3 junction, depending on whether reactive ion etching was used prior to metallization. Cross-sectional high-resolution microscopy and elemental mapping analysis show that the in situ-formed Ti-TiOx layer on (100) Ga2O3 is relatively thin (2-2.5 nm) and homogeneous, whereas that on (010) substrates is much thicker (3-5 nm) and shows nanoscale facet-like features at the interface. The anisotropic nature of monoclinic Ga2O3, including anisotropic surface energy and mass diffusivity, is likely to be the main cause of the differences observed under microscopy and in electrical properties. The findings here provide direct evidence and insights into the dependence of device performance on the atomic-scale structural anisotropy of ß-Ga2O3. Moreover, the investigative strategy here─combining comprehensive electrical and materials characterization of interfaces on different semiconductor orientations─can be applied to assess a variety of other anisotropic oxide junctions.