[Effects of Tranexamic Acid on Perioperative Blood Loss and Wound Hematoma Development in Lumbar Spine Surgery: a Prospective Randomized Study]. / Vliv tranexamové kyseliny na perioperacní krevní ztrátu a rozvoj hematomu v ráne u operací bederní pátere: prospektivní randomizovaná studie.

PURPOSE OF THE STUDY Tranexamic acid as a haemostatic agent is commonly used in multiple medical branches. Over the last decade, there has been a steep rise in the number of studies evaluating its effect, i.e. blood loss reduction in specific surgical procedures. The aim of our study was to evaluate the effect of tranexamic acid on reducing intraoperative blood loss, postoperative blood loss into the drain, total blood loss, transfusion requirements, and development of symptomatic wound hematoma in conventional single-level lumbar decompression and stabilization. MATERIAL AND METHODS The study included patients who had undergone a traditional open lumbar spine surgery in the form of single-level decompression and stabilisation. The patients were randomized into two groups. The study group received a 15 mg/kg dose of tranexamic acid intravenously during the induction of anaesthesia and then again 6 hours later. No tranexamic acid was administered to the control group. In all patients, intraoperative blood loss, postoperative blood loss into the drain, and therefore also total blood loss, transfusion requirements and potential development of a symptomatic postoperative wound hematoma requiring surgical evacuation were recorded. The data of the two groups were compared. RESULTS The cohort includes 162 patients, 81 in the study group and the same number in the control group. In the intraoperative blood loss assessment, no statistically significant difference between the two groups was observed; 430 (190-910) mL vs. 435 (200-900) mL. In case of post-operative drain blood loss, a statistically significantly lower volume was reported after the tranexamic acid administration; 405 (180-750) mL vs. 490 (210-820) mL. When evaluating the total blood loss, a statistically significant difference was also confirmed, namely in favour of the tranexamic acid; 860 (470-1410) mL vs. 910 (500- 1420) mL. The reduction of total blood loss did not result in a difference in the number of administered transfusions; transfusions were given to 4 patients in each group. A postoperative wound hematoma requiring surgical evacuation developed in 1 patient in the group with the tranexamic acid and in 4 patients in the control group, but the difference was not statistically significant with respect to the insufficient group size. No patient in our study experienced complications associated with tranexamic acid application. DISCUSSION The beneficial effect of tranexamic acid on reducing blood loss in lumbar spine surgeries has already been confirmed by numerous meta-analyses. The question remains in what types of procedures, at what dose and route of administration its effect is significant. To date, most of the studies have explored its effect in multi-level decompressions and stabilizations. Raksakietisak et al., for instance, report significant reduction in total blood loss from 900 (160, 4150) mL to 600 (200, 4750) mL following an intravenous injection of 2 bolus doses of 15 mg/kg tranexamic acid. In less extensive spinal surgeries, the effect of tranexamic acid may not be that distinct. In our study of single-level decompressions and stabilizations, no reduction in the actual intraoperative bleeding was confirmed at the given dosage. Its effect was seen only in the postoperative period in a significant reduction of blood loss into the drain, thus also in the total blood loss, although the difference between 910 (500, 1420) mL and 860 (470, 1410) mL was not that significant. CONCLUSIONS By intravenous application of tranexamic acid in 2 bolus doses in single-level decompression and stabilization of the lumbar spine a statistically significant reduction in postoperative blood loss into the drain and also total blood loss was confirmed. The reduction in the actual intraoperative blood loss was not statistically significant. No difference was observed in the number of administered transfusions. Following the tranexamic acid administration, a lower number of postoperative symptomatic wound hematomas was recorded, but the difference was not statistically significant. Key words: tranexamic acid, spinal surgeries, blood loss, postoperative hematoma.

Unusual foreign body in the nasal cavity after craniofacial injury.

A 68-year-old man with severe craniofacial trauma underwent endoscopic surgery for nasal cerebrospinal fluid leak. During the operation, a plastic object in the shape of a spectacle lens was found wedged in the left nasal passage, which we extracted. As subsequently established from the patient's documentation, it was a dislodged acrylic implant originally placed at the base of the orbit which was surgically treated after an injury to the facial skeleton thirty-five years ago. What is also rare about this is the fact that the patient had been examined for many years at the otorhinology department for purulent discharge from the left nasal cavity and impaired ventilation. The patient had also undergone an endoscopic examination of the nasal cavity during which an intranasal tumor was even suspected, but it was not histologically confirmed.

Phase-contrast enhanced synchrotron micro-tomography of human meniscus tissue.

OBJECTIVE: To investigate the feasibility of synchrotron radiation-based phase contrast enhanced micro-computed tomography (SR-PhC-µCT) for imaging of human meniscus. Quantitative parameters related to fiber orientation and crimping were evaluated as potential markers of tissue degeneration. DESIGN: Human meniscus specimens from 10 deceased donors were prepared using different preparation schemes: fresh frozen and thawed before imaging or fixed and paraffin-embedded. The samples were imaged using SR-PhC-µCT with an isotropic voxel size of 1.625 µm. Image quality was evaluated by visual inspection and spatial resolution. Fiber voxels were defined using a grey level threshold and a structure tensor analysis was applied to estimate collagen fiber orientation. The area at half maximum (FAHM) was calculated from angle histograms to quantify orientation distribution. Crimping period was calculated from the power spectrum of image profiles of crimped fibers. Parameters were compared to degenerative stage as evaluated by Pauli histopathological scoring. RESULTS: Image quality was similar between frozen and embedded samples and spatial resolutions ranged from 5.1 to 5.8 µm. Fiber structure, including crimping, was clearly visible in the images. Fibers appeared to be less organized closer to the tip of the meniscus. Fiber density might decrease slightly with degeneration. FAHM and crimping period did not show any clear association with histopathological scoring. CONCLUSION: SR-PhC-µCT is a feasible technique for high-resolution 3D imaging of fresh frozen meniscus tissue. Further work is needed to establish quantitative parameters that relate to tissue degeneration, but this imaging technique is promising for future studies of meniscus structure and biomechanical response.

Risk of biochemical recurrence in patients with a positive surgical margin after radical prostatectomy.

INTRODUCTION: Serum prostate specific antigen (PSA) is an irreplaceable marker in the detection and follow-up of patients with prostate cancer. In our analysis we addressed factors that could indicate the likelihood of biochemical recurrence (BCR) early after radical prostatectomy. We mainly focused on the positive surgical margin (R1). METHODS: Retrospective evaluation and analysis of the database of patients with prostate cancer after radical prostatectomy from 2001 to 2019. In total 1529 patients were enrolled in the study. The median follow-up was 48 months. The age of the patients ranged from 49 to 76 years. We used pre-operative PSA values, and the monitoring of the dynamics of 3rd generation PSA progression (detection limit 0.003 ng/ml) at month 1 and month 3 after surgery and then in 3-month intervals. We monitored the surgical margin positivity (R0 negative, R1 positive) and the Gleason score (GS) based on histological samples and we analysed the relationship to biochemical recurrence of the disease. RESULTS: The pre-operative PSA value did not show a direct relationship to the R1 risk. Patient values in the groups R1 and R0 differed only by 1.159 ng/ml (p=NS). The 3rd generation PSA value at month 1 after surgery was 50.82% higher in R1 patients (p>0.001). 50% of patients with R1 (29.5% patients of the total) did develop BCR during the follow-up period, while in patients with R0 (70.5% patients of the total) this proportion was 30% (p>0.001). Among those with GS 67, 47% developed BCR. The GS 810 group relapsed in 75% of the cases (p>0.001). CONCLUSION: According to our analysis 33% of the patients reached the stage of biochemical recurrence. We demonstrated a direct dependency between the risk of recurrence and the final Gleason score. The presence of R1 should not be viewed as a direct indication for adjuvant radiotherapy.

[Minimally Invasive Sacroiliac Joint Stabilization]. / Minimálne invazivní stabilizace sakroiliackého skloubení.

PURPOSE OF THE STUDY Sacroiliac joint dysfunction is defined as a permanent chronic pain originating from the sacroiliac joint, limiting the patient's daily activities. The purpose of this study was to evaluate the effectiveness of the minimally invasive sacroiliac joint stabilization by triangular titanium implants in patients with sacroiliac joint dysfunction. MATERIAL AND METHODS The prospective study evaluated the patients who had underwent a minimally invasive sacroiliac joint stabilization for sacroiliac joint dysfunction with the use of iFuse® implants. The surgery was performed solely under fluoroscopic guidance or together with the use of O-arm O2® mobile imaging system. The clinical condition, the Visual Analogue Scale preoperatively and one year postoperatively, previous surgeries in the lumbar spine region, the use of O-arm and occurrence of complications were recorded. The minimum follow-up period was 1 year. RESULTS The group was composed of 20 patients, of whom 4 men and 16 women. The mean age was 48.9 years. The surgeries covered 21 sacroiliac joints. Improvement of the clinical condition was reported in 17 cases (81.0%), no relief was observed in 4 cases (19%). The mean VAS score was 6.1 points preoperatively and decreased to 2.9 points postoperatively (p=0.0001). CONCLUSIONS The minimally invasive sacroiliac joint stabilization should be reserved for patients experiencing an intractable pain originating from the sacroiliac joint, in whom all non-operative therapy failed. Key words: minimally invasive sacroiliac joint stabilization, sacroiliac joint dysfunction, O-arm.

[URGENT SURGICAL OPERATIONS FOR CROHN'S DISEASE IN CHILDREN].

Aim - the improvement of treatment results of patients with complicated Crohn's disease based on study and analysis of own results of surgical interventions. Since 2008 to 2020 years 23 patients at the age 1,5-17 years old with Crohn's disease in 3 pediatric surgical hospitals have been observed. The article presents the analysis of surgical treatment of these patients with complications of main pathology. Diagnostics is integrated and includes clinical and laboratorian examination of patients, X-ray, endoscopic, sonography methods of examination and morphological research method of clinical biopsy. Complications of Crohn's disease were presented by intestinal obstructions (34,78% of cases), intestinal perforations (26,09%), acute appendicitis with mesadenitis (13,04%), intraabdominal abscesses (8,7%), intestinal hemorragia from inflammatory wart (4,35%), perianal inflammatory complications with fistulas (13,04%). The article has covered all possible methods of surgical operations depending on the type of complication. The most frequent surgical interventions were resections of intestinal stenosis with formation of intestinal stomas. The majority of patients have achieved good results after surgical interventions. 5 (23,81%) patients have got a relaparotomias because of such postoperative complications as anastomotic failure (1), recurrence of intestinal perforation (2) and recurrence of intestinal obstruction (2). Mortality has not been observed. Conclusions. 1. Because of Crohn's disease is a progressive disease, the opportunity of emergence of acute surgical complications of this pathology preserves. Our data show that urgent surgical complications of Crohn's disease in 47,83% of patients were the first manifestation of the disease, which was diagnosed during treatment and verified morphologically in the postoperative period. 2. In most cases surgical complications were intestinal obstruction (34,78% cases) and intestinal perforations (26,09%), and the most frequent surgical interventions for Crohn's disease in children were resections of the affected areas of the intestine with formation of intestinal stomas. 3. The modern tactic of surgical treatment of complicated of Crohn's disease in children based on local intestinal resections with intestinal stomas. 4. It is very important to use a combined approach combining conservative and surgical treatment. Surgical treatment and drug treatment of Crohn's disease should be complementary treatments.

Imaging Current-Induced Switching of Antiferromagnetic Domains in CuMnAs.

The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using x-ray magnetic linear dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the antiferromagnetic domain structure in microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between the average domain orientation and the anisotropy of the electrical resistance is demonstrated, with both showing reproducible switching in response to orthogonally applied current pulses. However, the behavior is inhomogeneous at the submicron level, highlighting the complex nature of the switching process in multidomain antiferromagnetic films.

[Metastatic Pituitary Disorders]. / Metastatické postizení hypofýzy.

BACKGROUND: Pituitary metastases are a rare complication of generalized cancer. Metastases to the pituitary gland occur in only 1% of patients operated on for sellar tumor. The most common presenting symptom in patients with pituitary metastases is diabetes insipidus, whereas this is rare in those with pituitary adenoma. MATERIAL AND METHODS: This publication presents the cases of two patients with pituitary metastases and a systematic review of the literature. English-language publications related to pituitary metastases and published from 1957 to 2016 were identified using the PubMed database. RESULTS: A total of 131 publications containing information about 259 patients (121 female and 138 male; mean age, 57.3 years) were identified. The most often metastasized breast carcinoma (24.6%) and lung carcinoma (23.8%), followed by thyroid carcinoma (11.3%), renal cell carcinoma (7.8%), hepatocellular carcinoma (4.3%), colorectal carcinoma (3.5%), and malignant melanoma (3.5%). The most frequent initial symptoms were manifestations of diabetes insipidus (39.6%), anterior pituitary deficiency (44.9%), perimeter disorders (51.6%), headache (37.6%), cranial nerve palsy (33.5%), and pseudoprolactinemia (16.7%). Radiotherapy (67.8%) and surgical treatment (63.9%) were the most frequently used treatment. CONCLUSION: The average survival time from the onset of metastatic disease was 11.8 months. Surgical therapy alone or in combination with radiation therapy does not prolong survival, but alleviates symptoms and improves quality of life.Key words: pituitary metastasis - diabetes insipidus - hypopituitarism - transsphenoidal surgery The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 13. 1. 2017Accepted: 4. 4. 2017.

[Autologous cranioplasty with a bone flap preserved subcutaneously in the mesogastrium]. / Autologní kranioplastika deponovanou kostní ploténkou v podkozí mezogastria.

INTRODUCTION: Cranioplasty with autologous bone flap is indicated in patients who have undergone decompressive craniectomy. Although it is an elective procedure, literature data indicate complication rates of up to 30%. The aim of this paper is to present our experience with cranioplasty with the patients own bone flap stored subcutaneously in the mesogastrium. METHODS: We retrospectively analyzed a set of 92 patients who had undergone cranioplasty after decompressive craniectomy using autologous graft preserved subcutaneously in the mesogastrium. The patients were clinically and radiologically examined before the surgery, and six weeks and one year after surgery. We evaluated the incidence of acute complications - wound hematoma, and late complications - infection and bone resorption. The postoperative cosmetic effect and patient discomfort from the stored bone flap also constituted an important aspect. RESULTS: The frequency of complications in our study group was 25%. Late complications were the most common, occurring with a frequency of 13%. These were mainly resorption of the bone flap (4.3%) and infectious complications (4.3%). Acute complications occurred with a frequency of 10.9% in our patient group. The most serious complication was cerebral edema of unknown origin leading to death of the patient. Unsatisfactory cosmetic effect as well as discomfort at the site where the flap was stored occurred in two cases. CONCLUSIONS: Cranioplasty is associated with a higher risk of complications in comparison with other elective procedures. Nevertheless, we regard cranioplasty with subcutaneously preserved bone flap as an inexpensive and suitable alternative to cryopreservation or alloplastic materials.Key words: cranioplasty complications of cranioplasty autologous cranioplasty decompressive craniectomy.

[АNALYSIS OF LETHALITY IN COMPLICATED DIABETIC FOOT SYNDROME AND SEPSIS].

There were examined in dynamics 724 patients, in whom complicated diabetic foot syndrome (DFS) was diagnosed, and in 71 (9.8%) of them the disease was complicated by sepsis. The state severity in a DFS patients have depended upon duration of purulent-necrotic process on the foot, in septic patients such dependence was not revealed. All the DFS patients without sepsis were operated on. In total 36 died (lethality 5.5%), in presence of sepsis - 42 (lethality 59.1%). The cause of sepsis in the patients, suffering complicated DFS, was predominantly a wet gangrene of the lower extremities. Among those, who were not operated on, 13 (30.9%) septic patients died, of them 5 ­ who refused operative intervention performance - died in first hours after admittance to hospital due to irreversible injury of organs and systems.

[THE DYNAMICS OF IMMUNOLOGICAL RESULTS OF PATIENTS WITH T-CELL SKIN LYMPHOMAS AND PSORIASIS BY THE THERAPY OF ACTIVATION MECHANISMS SANOGENESIS METHODS].

The therapy T-cell skin lymphoma and psoriasis by the application of activation mechanisms sanogenesis methods, such as: original--a treatment plasmapheresis, a standard heparin infusion; used for the first time--wobenzym; solutions of acid acetic food and sodium bicarbonate; known--the basic sanitations of concomitant diseases, photopheresis caused remissions in 79.6% patients with different stages T-cell skin lymphoma (observed over an 8-year span), and in 67% of patients with psoriasis (observed over an 6-year span). Depuration reactions (phagocytosis, pinocytosis, toxin neutralization) has been activated by detoxication of treatment plasmapheresis and heparin infusions. The topical therapy with wobenzym, solutions of acid acetic food and sodium bicarbonate renewed natural immune barrier of skin. Basic therapy of concomitant diseases enhanced of patient state of health and mobilized compensatory resources. Photopheresis initiated autoimmunization processes by malignant CD4+ lymphocytes. When remission was achieved, the parameters of cellular and humoral immunity returned to normal levels, or the parameters made worse in the absence of remission.

[The indices of quality of the donor's plasma, obtained by the methods of plasmapheresis and primary fractionation, using various hemopreservatives and leukocytic filters].

There was estimated quality of the plasm indices; so in comparison with the fractioning methods, using two regimens of the donor's blood centifugating, harvested with the help of various conservants, the most secure and functionally adequate plasm preparation was determined such, which is obtained with the help of plasmapheresis procedures. The expediency of application and introduction of the differentiated centrifugation technology, providing rational usage of a donor's blood, was determined. After conduction of leukofiltration of the conserved blood and plasm the residual cells content is reducing significantly, while preserving activity of the blood coagulation factors.

Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature.

Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls in the magnetic order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these textures that have high potential for terahertz dynamics, deflection-free motion and improved size scaling due to the absence of stray field. Here we show that topological spin textures, merons and antimerons, can be generated at room temperature and reversibly moved using electrical pulses in thin-film CuMnAs, a semimetallic antiferromagnet that is a testbed system for spintronic applications. The merons and antimerons are localized on 180° domain walls, and move in the direction of the current pulses. The electrical generation and manipulation of antiferromagnetic merons is a crucial step towards realizing the full potential of antiferromagnetic thin films as active components in high-density, high-speed magnetic memory devices.

[Percutaneous interspinous dynamic stabilization (in-space) in patients with degenerative disease of the lumbosacral spine - a prospective study]. / Perkutánní interspinózní dynamická stabilizace (In-Space) u nemocných s degenerativním onemocnením lumbosakrální pátere - prospektivní studie.

INTRODUCTION: Interspinous spacers are supposed to reduce the segmental extension with a decrease in the expansion of yellow ligaments into the spinal canal, thus avoiding the dynamic narrowing of the spinal canal and compression of nerve roots. The aim of this study was to evaluate clinical outcomes and post-operative complications during one year in patients mostly having suffered from spinal stenosis and treated by In-Space interspinous spacer (Synthes, USA). MATERIAL AND METHODS: A total of 25 patients aged between 25 and 73 (average age 52.6) years, including 18 males and 7 females, with degenerative disease of the lumbosacral spine were indicated for surgery and prospectively followed up. The patients were operated on under general anaesthesia in the prone position, using a minimally invasive lateral percutaneous approach, under fluoroscopic control. The ODI and VAS values as well as X- rays (Range Of Motion and Sagittal angle of the operated segment) 6 and 12 months after the surgery were compared to each other and to those before surgery. The results were statistically analyzed. RESULTS: The average ODI of the group was 47.2% before surgery and 17.48% 6 months (22.76% 12 months) after surgery, showing a statistically significant improvement by 63% (52% after 12 months). The average VAS of the group was 6.64 points before surgery and 2.96 points 6 months (2.8 points 12 months) after surgery, which showed a statistically significant improvement by 55.4% after 6 months (57.8% after 12 months) when compared to preoperative status. After surgery the lordotic sagittal angle remained in all cases; one year after surgery the angle increased due to the slight sinking of some implants. The extent of segmental motion was minimally changed (6.1° 6 months and 7.24° 12 months after surgery). No serious complications occurred. The effect of interspinous implants proved insufficient in two cases (one year and two years after surgery) and conversion to arthrodesis or decompression was performed. CONCLUSIONS: 1. Percutaneous, minimally invasive insertion of an In-Space interspinous spacer is an effective and safe method of dynamic stabilization not accompanied by any serious complications. 2. ODI improved by 63% 6 months after surgery with a decrease in this effect 12 months after surgery. VAS for axial and radicular pain, as reported by patients, improved on average by 55.4% 6 months and by 57.8% 12 months after surgery. 3. In all cases, the lordotic sagittal angle remained after surgery and the extent of segmental motion from flexion to extension was minimally changed.

Safety of Intranasal Insulin in Type 2 Diabetes on Systemic Insulin: A Double-Blinded Placebo-Controlled Sub-Study of Memaid Trial.

Aims: To determine safety of intranasal insulin (INI) in MemAID trial participants with diabetes treated with systemic insulins. Materials and Methods: This randomized, double-blinded trial consisted of 24-week INI or placebo treatment once daily and 24-week follow-up. Safety outcomes were: 1) Short-term effects on glycemic variability, hypoglycemic episodes on continuous glucose monitoring (CGM) at baseline and on-treatment. 2) Long-term effects on glucose metabolism and weight on INI/placebo treatment and post-treatment follow-up. Of 86 screened subjects, 14 were randomized, 9 (5 INI, 4 Placebo) completed CGM at baseline and on-treatment, and 5 (2 INI, 3 Placebo) completed treatment and follow-up. Results: INI was safe and was not associated with serious adverse events, hypoglycemic episodes or weight gain. INI administration did not acutely affect capillary glucose. Glycemic variability on CGM decreased with INI, compared to baseline. On INI treatment, there was a long-term trend toward lower HbA1c, plasma glucose and insulin. No interactions with subcutaneous insulins were observed. Conclusions: INI is safe in older people with diabetes treated with systemic insulins, and it is not associated with adverse events, hypoglycemia or weight gain. Future studies are needed to determine whether INI administration can reduce glycemic variability, improve insulin sensitivity and thus potentially lessen diabetes burden in this population.

Ultrashort spin-orbit torque generated by femtosecond laser pulses.

To realize the very objective of spintronics, namely the development of ultra-high frequency and energy-efficient electronic devices, an ultrafast and scalable approach to switch magnetic bits is required. Magnetization switching with spin currents generated by the spin-orbit interaction at ferromagnetic/non-magnetic interfaces is one of such scalable approaches, where the ultimate switching speed is limited by the Larmor precession frequency. Understanding the magnetization precession dynamics induced by spin-orbit torques (SOTs) is therefore of great importance. Here we demonstrate generation of ultrashort SOT pulses that excite Larmor precession at an epitaxial Fe/GaAs interface by converting femtosecond laser pulses into high-amplitude current pulses in an electrically biased p-i-n photodiode. We control the polarity, amplitude, and duration of the current pulses and, most importantly, also their propagation direction with respect to the crystal orientation. The SOT origin of the excited Larmor precession was revealed by a detailed analysis of the precession phase and amplitude at different experimental conditions.

11q23/MLL rearrangements in adult acute leukemia.

AIM: To detect the frequency, diagnostic and prognostic significance of 11q23/MLL rearrangements and to determine the chromosomes that are most frequently involved in 11q23/MLL abnormalities in adult acute leukemia (AL). MATERIALS AND METHODS: Cytogenetic investigations of bone marrow and/or peripheral blood cells from 140 patients with acute myeloid leukemia (AML) and 57 patients with acute lymphoblastic leukemia (ALL) were performed. The methods of conventional cytogenetics (GTG-banding) and fluorescence in situ hybridization were used. RESULTS: Chromosomal abnormalities in leukemia cells were found by conventional cytogenetic methods in 80 (57%) and 37 (65%) adult patients with AML and ALL, respectively. 11q23/MLL rearrangements were found in 7 (5%) and 8 (14%) patients with AML and ALL, respectively. Among them, 8 (53.4%) patients had translocations, 2 (13.3%) - had deletions and 5 (33.3%) patients had trisomies or tetrasomies of chromosome 11. With respect to the distribution of partner chromosomes involved in 11q23/MLL translocations chromosome 4 was found to participate in 3 (37.5%) cases of 11q23/MLL translocations, 9 - in 2 (25%) cases and chromosomes 10, 14 and non-identified chromosome were involved in 1 (12.5%) case each. Nine patients (60%), besides abnormal ones, had 9-86% normal metaphases in their karyotypes. Of 15 patients with 11q23/MLL rearrangements, 5 (33%) patients had only 11q23/MLL rearrangements, whereas other 10 (67%) - had additional cytogenetic abnormalities, besides 11q23/MLL rearrangements. CONCLUSIONS: Chromosomal abnormalities of various kinds were found in 57% and 65% adult patients with AML and ALL, respectively. The frequency of 11q23/MLL rearrangements in patients with AML and ALL was 5% and 14%, respectively. Since AL patients with 11q23/MLL rearrangements are attributed to cytogenetic categories of AL with a poor or intermediate risk prognosis, cytogenetic methods should be included in the standard examination of AL patients for diagnosis, prognosis and selection of the optimal treatment strategy.

Microscopic analysis of the valence band and impurity band theories of (Ga,Mn)As.

We analyze microscopically the valence and impurity band models of ferromagnetic (Ga,Mn)As. We find that the tight-binding Anderson approach with conventional parametrization and the full potential local-density approximation+U calculations give a very similar band structure whose microscopic spectral character is consistent with the physical premise of the k·p kinetic-exchange model. On the other hand, the various models with a band structure comprising an impurity band detached from the valence band assume mutually incompatible microscopic spectral character. By adapting the tight-binding Anderson calculations individually to each of the impurity band pictures in the single Mn impurity limit and then by exploring the entire doping range, we find that a detached impurity band does not persist in any of these models in ferromagnetic (Ga,Mn)As.

Systematic study of Mn-doping trends in optical properties of (Ga,Mn)As.

We report on a systematic study of optical properties of (Ga,Mn)As epilayers spanning the wide range of accessible Mn(Ga) dopings. The material synthesis was optimized for each nominal Mn doping in order to obtain films which are as close as possible to uniform uncompensated (Ga,Mn)As mixed crystals. We observe a broad maximum in the mid-infrared absorption spectra whose position exhibits a prevailing blueshift for increasing Mn doping. In the visible range, a peak in the magnetic circular dichroism also shifts with increasing Mn doping. The results are consistent with the description of ferromagnetic (Ga,Mn)As based on the microscopic valence band theory. They also imply that opposite trends seen previously in the optical data on a limited number of samples are not generic and cannot serve as an experimental basis for postulating the impurity band model of ferromagnetic (Ga,Mn)As.

Pattern formation in semiconductors.

In semiconductors, nonlinear generation and recombination processes of free carriers and nonlinear charge transport can give rise to non-equilibrium phase transitions, . At low temperatures, the basic nonlinearity is due to the autocatalytic generation of free carriers by impact ionization of shallow impurities. The electric field accelerates free electrons, causing an abrupt increase in free carrier density at a critical electric field. In static electric fields, this nonlinearity is known to yield complex filamentary current patterns bound to electric contacts.