Clinical and Molecular Characterization of Nine Novel Antithrombin Mutations.

Antithrombin (AT) is the major plasma inhibitor of thrombin (FIIa) and activated factor X (FXa), and antithrombin deficiency (ATD) is one of the most severe thrombophilic disorders. In this study, we identified nine novel AT mutations and investigated their genotype-phenotype correlations. Clinical and laboratory data from patients were collected, and the nine mutant AT proteins (p.Arg14Lys, p.Cys32Tyr, p.Arg78Gly, p.Met121Arg, p.Leu245Pro, p.Leu270Argfs*14, p.Asn450Ile, p.Gly456delins_Ala_Thr and p.Pro461Thr) were expressed in HEK293 cells; then, Western blotting, N-Glycosidase F digestion, and ELISA were used to detect wild-type and mutant AT. RT-qPCR was performed to determine the expression of AT mRNA from the transfected cells. Functional studies (AT activity in the presence and in the absence of heparin and heparin-binding studies with the surface plasmon resonance method) were carried out. Mutations were also investigated by in silico methods. Type I ATD caused by altered protein synthesis (p.Cys32Tyr, p.Leu270Argfs*14, p.Asn450Ile) or secretion disorder (p.Met121Arg, p.Leu245Pro, p.Gly456delins_Ala_Thr) was proved in six mutants, while type II heparin-binding-site ATD (p.Arg78Gly) and pleiotropic-effect ATD (p.Pro461Thr) were suggested in two mutants. Finally, the pathogenic role of p.Arg14Lys was equivocal. We provided evidence to understand the pathogenic nature of novel SERPINC1 mutations through in vitro expression studies.

Low-burden TP53 mutations represent frequent genetic events in CLL with an increased risk for treatment initiation.

TP53 aberrations predict chemoresistance and represent a contraindication for the use of standard chemoimmunotherapy in chronic lymphocytic leukaemia (CLL). Recent next-generation sequencing (NGS)-based studies have identified frequent low-burden TP53 mutations with variant allele frequencies below 10%, but the clinical impact of these low-burden TP53 mutations is still a matter of debate. In this study, we aimed to scrutinise the subclonal architecture and clinical impact of TP53 mutations using a sensitive, NGS-based mutation analysis in a 'real-world' cohort of 901 patients with CLL. In total, 225 TP53 mutations were identified in 17.5% (158/901) of the patients; 48% of these alterations represented high-burden mutations, while 52% were low-burden TP53 mutations. Low-burden mutations as sole alterations were identified in 39% (62/158) of all mutated cases with 82% (51/62) of these being represented by a single low-burden TP53 mutation. Patients harbouring low-burden TP53 mutations had significantly lower time to first treatment compared to patients with wild-type TP53. Our study has expanded the knowledge on the frequency, clonal architecture, and clinical impact of low-burden TP53 mutations. By demonstrating that patients with sole low-burden TP53 variants represent more than one-third of patients with TP53 mutations and have an increased risk for treatment initiation, our findings strengthen the need to redefine the threshold of TP53 variant reporting to below 10% in the routine diagnostic setting.

Successful treatment of acquired haemophilia A / A szerzett haemophilia A sikeres kezelése.

Összefoglaló. A szerzett haemophilia A ritka autoimmun betegség, melyben gátlótest képzodik a VIII. véralvadási faktor ellen. Az inhibitor véralvadásra gyakorolt hatása súlyos, életet veszélyezteto vérzéses állapotot idéz elo. A beteg élete a gyors diagnózison múlik: a jellemzo klinikai kép mellett a megnyúlt, normálplazmával nem korrigálható aktivált parciális tromboplasztinido megléte esetén a kórkép alapos gyanúja merül fel. Egy súlyos vérszegénység miatt kórházunkba beutalt nobeteg esetében a szerzett haemophilia A a felvételt követo napon már diagnosztizálásra került. A vérzés megszüntetésére aktivált protrombinkomplex-koncentrátumot alkalmaztunk, valamint immunszuppresszív terápiát vezettünk be. A kórkép korai felismerése és a megfelelo kezelés azonnali megkezdése a beteg gyógyulását eredményezte. Esetünkkel arra szeretnénk felhívni a figyelmet, hogy a szerzett haemophilia A gyors diagnózisa egyszeru, könnyen hozzáférheto véralvadási paraméter, az aktivált parciális tromboplasztinido meghatározásán és nem korrigálható megnyúlásának felismerésén múlik. Orv Hetil. 2021; 162(49): 1977-1981. Summary. Acquired haemophilia A is a rare autoimmune disorder, in which antibodies are formed against coagulation factor VIII. The effect of the inhibitor on blood clotting results in severe, life-threatening bleeding diathesis. The patient's life depends on the rapid diagnosis: besides the characteristic clinical presentation, a prolonged activated partial thromboplastin time, which is not corrigible with normal plasma, suggests the existence of the disorder. In the case of the female patient who was referred to our hospital due to severe anaemia, acquired haemophilia A was diagnosed rapidly, the day after her admission. We used activated prothrombin complex concentrate to stop the bleeding, and introduced immunosuppressive therapy. The early recognition of the disease and immediate initiation of adequate treatment resulted in the patient's full recovery. With our case presentation, we would like to draw attention to the fact that the rapid diagnosis of acquired haemophilia A depends on the determination of a simple, easily accessible coagulation parameter, the activated partial thromboplastin time and on the immediate recognition of its incorrigible prolongation. Orv Hetil. 2021; 162(49): 1977-1981.

High penetrance of inferior vena cava system atresia in severe thrombophilia caused by homozygous antithrombin Budapest 3 variant: Description of a new syndrome.

Atresia of inferior vena cava (IVC) is a rare congenital malformation associated with high risk of venous thrombosis that still has unknown etiology, although intrauterine IVC thrombosis has been suggested to be involved. The identification of IVC atresia in a case with early idiopathic venous thrombosis and antithrombin deficiency caused by the homozygous SERPINC1 c.391C > T variant (p.Leu131Phe; antithrombin Budapest 3) encouraged us to evaluate the role of this severe thrombophilia in this vascular abnormality. We have done a cross-sectional study in previously identified cohorts of patients homozygous for the Budapest 3 variant (N = 61) selected from 1118 patients with congenital antithrombin deficiency identified in two different populations: Spain (N = 692) and Hungary (N = 426). Image analysis included computed tomography and phlebography. Atresia of the IVC system was observed in 17/24 cases (70.8%, 95% confidence interval [CI]: 48.9%-87.3%) homozygous for antithrombin Budapest 3 with available computed tomography (5/8 and 12/16 in the Spanish and Hungarian cohorts, respectively), 16 had an absence of infrarenal IVC and one had atresia of the left common iliac vein. All cases with vascular defects had compensatory mechanisms, azygos-hemiazygos continuation or double IVC, and seven also had other congenital anomalies. Short tandem repeat analysis supported the specific association of the IVC system atresia with SERPINC1. We show the first evidence of the association of a severe thrombophilia with IVC system atresia, supporting the possibility that a thrombosis in the developing fetal vessels is the reason for this anomaly. Our hypothesis-generating results encourage further studies to investigate severe thrombophilic states in patients with atresia of IVC.

Screening and monitoring of the BTKC481S mutation in a real-world cohort of patients with relapsed/refractory chronic lymphocytic leukaemia during ibrutinib therapy.

The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has revolutionised the therapeutic landscape of chronic lymphocytic leukaemia (CLL). Acquired mutations emerging at position C481 in the BTK tyrosine kinase domain are the predominant genetic alterations associated with secondary ibrutinib resistance. To assess the correlation between disease progression, and the emergence and temporal dynamics of the most common resistance mutation BTKC481S , sensitive (10-4 ) time-resolved screening was performed in 83 relapsed/refractory CLL patients during single-agent ibrutinib treatment. With a median follow-up time of 40 months, BTKC481S was detected in 48·2% (40/83) of the patients, with 80·0% (32/40) of them showing disease progression during the examined period. In these 32 cases, representing 72·7% (32/44) of all patients experiencing relapse, emergence of the BTKC481S mutation preceded the symptoms of clinical relapse with a median of nine months. Subsequent Bcl-2 inhibition therapy applied in 28/32 patients harbouring BTKC481S and progressing on ibrutinib conferred clinical and molecular remission across the patients. Our study demonstrates the clinical value of sensitive BTKC481S monitoring with the largest longitudinally analysed real-world patient cohort reported to date and validates the feasibility of an early prediction of relapse in the majority of ibrutinib-treated relapsed/refractory CLL patients experiencing disease progression.

[Investigation and treatment of prefibrotic/early primary myelofibrosis. A case study]. / A korai/praefibroticus primer myelofibrosis kivizsgálása és kezelése egy eset kapcsán.

Moderate thrombocytosis can accompany several diseases (bleeding, inflammation, iron deficiency, or autoimmune diseases), but hematologic examination is strongly recommended in a patient with persistent platelet count above 450 G/L unless reactive origin can be confirmed. The 47-year-old woman's medical history included hypertonia, asthma bronchiale, and endometriosis. In March 2015, she underwent laboratory examination due to weight loss and lack of appetite. Her results showed elevated thrombocyte count (617 G/L), but no iron deficiency. She presented in our clinic on 07. 04. 2015 with acute pain below her left hypochondrial region, but simple imaging examinations showed no difference to explain it. Abdominal CT revealed a 4.5 cm thrombus which protruded into the left renal artery, blocking it. We started APTI- (activated partial thromboplastin time) monitored continuous intravenous treatment with unfractionated heparin. The JAK2V617F mutation analysis came back positive. Subsequent bone marrow examination revealed prefibrotic/early stage myelofibrosis, prompting treatment with hydroxyurea. The applied treatments led to the disappearance of the patient's symptoms accompanied by the gradual normalisation of the thrombocyte count. Moderate thrombocytosis is often secondary, but if it persists and is accompanied by mainly thromboembolic events, the risk of diseases of the haematopoietic system, primarily Philadelphia chromosome negative chronic myeloproliferative disease should also be considered. Clinically, essential thrombocythaemia and the prefibrotic/early stage of myelofibrosis can be very similar. Differential diagnosis is only possible through the histological examination of the bone marrow, which becomes indispensible due to the difference in prognosis and treatment options. Orv Hetil. 2018; 159(15): 603-609.

A decade-long clinical experience on the prophylactic use of activated prothrombin complex concentrate in acquired haemophilia A: a case series from a tertiary care centre.

: In acquired haemophilia A (AHA), risk for recurrent bleeding exists until the inhibitor is detectable. Thus, patients with persisting inhibitor may benefit from prophylaxis with activated prothrombin complex concentrate (aPCC). Potential thromboembolic complications and cost are also factors to consider. Today, no high level evidence or clear recommendations are available on aPCC prophylaxis in AHA. Recently, a small prospective study demonstrated a favourable outcome with short-term, daily administered aPCC infusion. Here we report a retrospective case series of 19 patients with AHA to demonstrate our practice on aPCC prophylaxis. In our practice, clinical bleeding tendency guided our decision on the initiation of aPCC prophylaxis. In patients with serious bleeding tendency, aPCC infusion was prolonged beyond bleeding resolution in a twice-weekly or thrice-weekly regimen. Serious bleeding phenotype included a single episode of life-threatening bleeding or recurrent, severe haemorrhages. Patients who did not present such events were treated on-demand. The preventive dose of aPCC was equal with the lowest effective therapeutic dose. Prophylaxis was continued until the inhibitor disappeared. Eleven patients received aPCC prophylaxis. In nine cases, prophylaxis lasted beyond two months. No severe bleeding developed spontaneously and no thromboembolic complication occurred in the median 16 weeks (interquartile range 9-34) duration of prophylaxis. Eight patients of the nonprophylaxis group did not present any severe haemorrhage. According to our experience, we consider prophylaxis with aPCC effective and well tolerated for patients with AHA and serious bleeding tendency, until the acquired inhibitor persists.

Clinical and laboratory characteristics of antithrombin deficiencies: A large cohort study from a single diagnostic center.

INTRODUCTION: Inherited antithrombin (AT) deficiency is a heterogeneous disease. Due to low prevalence, only a few studies are available concerning genotype-phenotype associations. The aim was to describe the clinical, laboratory and genetic characteristics of AT deficiency in a large cohort including children and to add further laboratory data on the different sensitivity of functional AT assays. PATIENTS AND METHODS: Non-related AT deficient patients (n=156) and their family members (total n=246) were recruited. Clinical and laboratory data were collected, the mutation spectrum of SERPINC1 was described. Three different AT functional assays were explored. RESULTS: Thirty-one SERPINC1 mutations including 11 novel ones and high mutation detection rate (98%) were detected. Heparin binding site deficiency (type IIHBS) was the most frequent (75.6%) including AT Budapest3 (ATBp3), AT Padua I and AT Basel (86%, 9% and 4% of type IIHBS, respectively). Clinical and laboratory phenotypes of IIHBS were heterogeneous and dependent on the specific mutation. Arterial thrombosis and pregnancy complications were the most frequent in AT Basel and AT Padua I, respectively. Median age at the time of thrombosis was the lowest in ATBp3 homozygotes. The functional assay with high heparin concentration and pH7.4 as assay conditions had low (44%) sensitivity for ATBp3 and it was insensitive for AT Basel and Padua I. CONCLUSION: Type IIHBS deficiencies behave differently in clinical and laboratory phenotypes from each other and from other AT deficiencies. Heparin concentration and pH seem to be the key factors influencing the sensitivity of AT functional assays to IIHBS.

Antithrombin Debrecen (p.Leu205Pro) - Clinical and molecular characterization of a novel mutation associated with severe thrombotic tendency.

INTRODUCTION: Hereditary antithrombin (AT) deficiency is a rare thrombophilic disorder with heterogeneous genetic background and various clinical presentations. In this study we identified a novel AT mutation. Genotype-phenotype correlations, molecular characteristics and thrombotic manifestations of the mutation were investigated. MATERIALS AND METHODS: Thirty-one members of a single family were included. Clinical data was collected regarding thrombotic history. The mutation was identified by direct sequencing of the SERPINC1 gene. HEK293 cells were transfected with wild type and mutant SERPINC1 plasmids. Western blotting, ELISA and functional amidolytic assay were used to detect wild type and mutant AT. After double immunostaining, confocal laser scanning microscopy was used to localize mutant AT in the cells. Molecular modeling was carried out to study the structural-functional consequences of the mutation. RESULTS: Unprovoked venous thrombotic events at early age, fatal first episodes and recurrences were observed in the affected individuals. The median AT activity was 59%. Genetic analysis revealed heterozygous form of the novel mutation p.Leu205Pro (AT Debrecen). The mutant AT was expressed and synthesized in HEK293 cells but only a small amount was secreted. The majority was trapped intracellularly in the trans­Golgi and 26S proteasome. The mutation is suspected to cause considerable structural distortion of the protein. The low specific activity of the mutant AT suggested functional abnormality. CONCLUSIONS: AT Debrecen was associated with very severe thrombotic tendency. The mutation led to misfolded AT, impaired secretion and altered function. Detailed clinical and molecular characterization of a pathogenic mutation might provide valuable information for individualized management.

Evaluation of flow cytometric HIT assays in relation to an IgG-Specific immunoassay and clinical outcome.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe side effect of heparin treatment caused by platelet activating IgG antibodies generated against the platelet factor 4 (PF4)-heparin complex. Thrombocytopenia and thrombosis are the leading clinical symptoms of HIT. METHODS: The clinical pretest probability of HIT was evaluated by the 4T score system. Laboratory testing of HIT was performed by immunological detection of antibodies against PF4-heparin complex (EIA) and two functional assays. Heparin-dependent activation of donor platelets by patient plasma was detected by flow cytometry. Increased binding of Annexin-V to platelets and elevated number of platelet-derived microparticles (PMP) were the indicators of platelet activation. RESULTS: EIA for IgG isotype HIT antibodies was performed in 405 suspected HIT patients. Based on negative EIA results, HIT was excluded in 365 (90%) of cases. In 40 patients with positive EIA test result functional tests were performed. Platelet activating antibodies were detected in 17 cases by Annexin V binding. PMP count analysis provided nearly identical results. The probability of a positive flow cytometric assay result was higher in patients with elevated antibody titer. 71% of patients with positive EIA and functional assay had thrombosis. CONCLUSIONS: EIA is an important first line laboratory test in the diagnosis of HIT; however, HIT must be confirmed by a functional test. Annexin V binding and PMP assays using flow cytometry are functional HIT tests convenient in a clinical diagnostic laboratory. The positive results of functional assays may predict the onset of thrombosis. © 2016 International Clinical Cytometry Society.

Management and outcome of pregnancies in women with antithrombin deficiency: a single-center experience and review of literature.

Women with antithrombin (AT) deficiency have an increased risk for pregnancy-associated venous thromboembolism (VTE) and adverse pregnancy outcome. AT deficiency is a rare thrombophilia with heterogeneous genetic background. Owing to the few cases reported in the literature, management strategies of pregnancy with AT deficiency are inconsistent. Our aim was to examine the type of the genetic defect, management, maternal, and pregnancy outcome in patients with hereditary AT deficiency. Five expectant mothers with AT deficiency were followed in our center to evaluate thrombotic events, and maternal and pregnancy outcomes. AT gene sequencing was performed in all cases, and levels of AT and anti-activated factor X were regularly measured to guide the risk-adopted anticoagulant prophylaxis. Three mothers had homozygous type II heparin-binding site mutations and two had heterozygous type I mutations of the gene encoding AT. Two women had additional factor V Leiden heterozygous mutations. Three maternal VTEs--four healthy newborns and five pregnancy losses--were observed. The risk of patients to VTE and adverse pregnancy outcome was found to associate with the homozygous type II heparin-binding site mutation of the AT gene. High risk of maternal VTE and frequent pregnancy complications were observed to associate with AT deficiency. Our results support the need of individualized, risk-adopted anticoagulant therapy in patients with AT deficiency.

Catheter-directed thrombolysis in inflammatory bowel diseases: report of a case.

In patients with inflammatory bowel diseases (IBD) the prevalence of thrombosis is 6.2%, the average incidence of thromboembolism (TE) is 3.6 times higher compared to normal population. The TE is a common extraintestinal complication of IBD, squarely associated with the IBD activity. The application of anticoagulant and thrombolytic therapy in severe IBD is an unresolved issue. Herein we report the first case in literature of an active IBD patient with an upper limb acute arterial occlusion and successful catheter-directed thrombolysis (CDT). A 46-year-old male patient is reported who had Crohn's disease for 10 years. His right hand suddenly became cold and painful. Angiography proved acute occlusion of the brachial and radial artery. Vascular surgery intervention was not applicable. Endoscopy showed extended, severe inflammation of the colon. Despite the severe endoscopic findings, frequent bloody stools and moderate anaemia, CDT with recombinant tissue plasminogen activator was performed. The control angiography proved improvement, the radial artery pulse appeared. No bleeding complication was observed. This case supports that CDT-after careful estimation of the bleeding risk-can be effective and safe in patients with severe or life-threatening TE and active IBD.

Acquired haemophilia: an often overlooked cause of bleeding - experience from a Hungarian tertiary care centre.

Acquired haemophilia is a potentially life-threatening bleeding disorder. Its early diagnosis and treatment is of major importance. We evaluated the elapsed time between the first presentation of the bleeding symptoms and the correct diagnosis in the cases of the acquired haemophilia patients referred to our centre between 1999 and 2011. The causes and consequences of the often delayed diagnosis were also examined. The clinical and laboratory data of 13 patients with acquired haemophilia were analysed. Eleven patients had inhibitors to factor VIII (FVIII), in one case the autoantibody developed to factor XIII (FXIII) and in one to factor V (FV). The median period between the onset of the bleeding symptoms and the correct diagnosis was 1.5 months (3.0 days-9.0 months). In four cases 4.0-9.0 months were needed to establish the diagnosis. The main reason of this delay was that either the prothrombin time was used exclusively to evaluate haemostasis in primary care and also in some secondary care centres, or the prolonged activated partial thromboplastin time went unnoticed despite the obvious bleeding symptoms. Our observation underlines the importance of early referral of patients with unexplained bleeding symptoms to centres with appropriate laboratory facilities and experience in the diagnosis of bleeding disorders.

Stem cell therapy: a promising and prospective approach in the treatment of patients with severe Buerger's disease.

No effective blood-flow enhancement therapies are available for patients with severe peripheral arterial disease (SPAD), thus amputation remains the only option for relief of rest pain or gangrene. Autologous bone marrow-derived stem cell therapy (ABMSCT) is an emerging modality to induce angiogenesis from endothelial progenitors. A total of 5 patients with SPAD were treated by ABMSCT using isolated CD34+ cells with characterized phenotype administered by intramuscular injections. The follow-up before and 1, 3, 6, 9, and 12 months after ABMSCT was based on clinical (rest pain, walking distance without pain, nonhealing ulcers, ankle-brachial index [ABI]) and laboratory (angiography, duplex and laser ultrasonography, TcPO(2)) parameters. Significant improvement of pain and walking distance was observed in all patients. Nonhealing ulcers disappeared in 3 patients and became smaller and thinner in 1 patient. The average of ABI improved significantly on the treated limb but did not change on the contralateral limb. New collaterals were detected by angiography in 3 patients, but duplex ultrasonography detected improvement in one patient only. Laser ultrasonography showed a mild significant change, TcPO(2) values improved mainly on the foot. Severe adverse events were not observed. We conclude that ABMSCT with isolated CD34+ cells is safe, effective, and results in sustained clinical benefit for patients with SPAD.

[Autologous bone marrow-derived stem cell therapy in patients with severe peripheral arterial disorder]. / Autológ csontvelôi eredetû ôssejtterápia eredménye elôrehaladott perifériás artériás érbetegségben.

BACKGROUND AND AIMS: Amputation is the only current option for relief of rest pain or gangrene in patients with severe peripheral arterial disease. Up to now, no effective blood-flow enhancement therapies are available. Autologous bone marrow-derived stem cell transplantation is an arising therapy modality with an option of building new blood vessels through endothelial stem and/or progenitor cells. PATIENTS AND METHODS: Five patients with severe peripheral arterial disorder were treated by autologous bone marrow-derived stem cell therapy. CD34+, CD133+ and CD45+/- cell number and ratio were determined. CD34+ cells were isolated by magnetic separation and collected into a 10 ml sample. The cell suspension was administered by local intramuscular injections (0.5-1.0 ml injections in the musculus gastrocnemius). The follow-up (before; 1, 3, 6, 9 and 12 months after the autologous bone marrow-derived stem cell therapy) based on clinical (rest pain, walking distance without pain, changes of non-healing ischaemic ulcers, ankle-brachial index) and laboratory (angiography, Color- and Laser-Doppler scan, measurement of transcutaneous oxygen tension and endothelial function test) parameters was documented and analyzed. RESULTS: Improvement of pain and walking distance was observed in all five cases. In three cases the non-healing ischaemic ulcers disappeared, in one other case they became smaller and thinner, and in one case no change was realized. The average of ankle-brachial index improved significantly (before: 0.41, twelve months after: 0.83). New collaterals were detected by angiography in three patients, but duplex ultrasonography detected improvement in one patient only. Before and 1, 6 and 12 months after stem cell therapy the transcutaneous oxygen tension changed on the foot from 18.80/16.78/23.83/37.50 mmHg, and on the calf from 36.66/31.25/45.00/37.30 mmHg. The macro- and microcirculation parameters did not show improvement after 1 month, however, after 3, 6, 9 and 12 months improved parameters were recorded. Severe adverse events were not observed. In one case elevated level of serum creatinine phosphokinase, and in another case a mild form of vasculitis were detected. CONCLUSION: autologous bone marrow-derived stem cell therapy with isolated CD34+ cells is effective, safe and results in sustained clinical benefit for patients with severe peripheral arterial disease.

[Local thrombolysis in the treatment of peripheral arterial vascular diseases]. / Lokális thrombolyticus kezelés perifériás artériás érbetegségben.

While atherosclerosis develops in a progressive manner, acute arterial thrombosis and embolism are characterized by fulminant occlusion of vessels. Special localisation of atherosclerotic plaques might result in severe and life threatening clinical symptoms. Multidisciplinary consultations of angiologist, radiologist and surgeon are necessary to identify the most proper diagnosis, and urgent intervention should be taken which nowadays involves local thrombolysis, too. The essence of this method is a prolonged, intravenous infusion of tissue plasminogen activator administered locally into the thrombus via an intraarterial catheter. Revascularisation can be controlled by angiography. The authors present the indications and contraindications of local thrombolysis in peripheral arterial disease and also demonstrate two cases which support the importance of this question. Data of some recent publications are also discussed. This emphasizes that local thrombolysis is equivalent to surgical possibilities. In specific cases, with complex clinical situations this method might be the first choice of treatment. Finally the most important conclusions and future prospects are presented.