The histology and genetic characteristics of PDX tumour models were stable over subsequent passages. Lymphoma transformation occurred in five cases , and all were in the NOG mouse, with none in the nude mouse. Together, the present study identified Lauren classification, tumour cell percentages, and ex vivo times along with overall procedure times, as key determinants for successful PDX engraftment. Furthermore, genetic and histological characteristics were highly consistent between primary and PDX tumours, which provide realistic paraclinical models, enabling personalised development of treatment options for gastric cancer.The patient-derived xenograft (PDX) model is emerging as a promising translational platform to duplicate the characteristics of tumours. However, few studies have reported detailed histological and genomic analyses for model fidelity and for factors affecting successful model establishment of gastric cancer. Here, we generated PDX tumours surgically-derived from 62 gastric cancer patients. Fifteen PDX models were successfully established  and passaged to maintain tumours in immune-compromised mice. Diffuse type and low tumour cell percentage were negatively correlated with success rates ( The baseline characteristics of donor patients are summarized in PDX tumours were initially generated in F1 mice, then implanted into F2 mice in 15 cases . p = 0.005). In addition, higher tumour cell percentages in the representative tissues were correlated with higher success rates (p = 0.025).To investigate potential factors related to the success of PDX tumours, we classified the parameters into three groups: patient characteristics, pathological tumour characteristics, and experimental parameters. There were no statistically significant parameters correlated with success of PDX tumours in patient characteristics such as age, gender, co-morbidity, history of smoking and alcohol, and no statistically significant parameters correlated with the success of PDX tumours in laboratory parameters, including tumour markers such as carcinoembryonic antigen (CEA) and carbohydrate antigen 19–9 (CA19–9) . Regardiex vivo times were shorter in successful cases than unsuccessful cases . When multiple pieces were implanted in a single animal, the success rate was higher (38.9%) than for implantation of a single piece (18.2%), but this difference was not statistically significant (p = 0.108). Other experimental parameters, such as the mouse strain, implantation site, or using Matrigel were not correlated with engraftment success . The success rate was 8.0% for nude mice (6 out of 75) and 10.5% for NOG mice (9 out of 86). Furthermore, 10.7% of subcutaneous implantations were successful (14 out of 131), while only 3.3% of subrenal capsule implantations were successful (1 out of 30), and Matrigel-embedded tumours did not improve the engraftment success . In whole exome sequencing analysis, some genetic variations in 726 cancer related genes were noticed across five F3 tumours of GA013 case when analysed without additional high-quality filters . When apin situ hybridization (ISH), indicating they were related to EBV-associated B-cell lymphoma . In all five cases with histological changes, tumour tissues obtained from F1 mice showed a lymphocytic dominant pattern, regardless of primary tumour histology. Immunohistochemistry (IHC) showed that these tumours were cytokeratin (CK) negative, but the cells strongly stained for CD20 and Epstein-Barr virus (EBV) early RNA (EBER) by lymphoma . These lp = 0.022), percentage of tumour cells (p = 0.044), and ex vivo time (p = 0.013) correlated with engraftment success (n = 10), but overall procedure time was not statistically significant (p = 0.054).Retaining histological and genetic features of the patient tumour is the most important aspect of PDX models. It has been reported that the histology of primary tumours (F0) was maintained through successive generations in various cancers, including gastric cancer132021222313222325262728ex vivo time and overall procedure time were the only significant experimental parameters affecting the success of establishing PDX tumour models for gastric cancer. Ischemic injury is closely related to viability of cells, and associated with low survival of grafts in organ transplantation313213183618In the present study, we identified parameters correlated with engraftment success, to improve the success rate of future PDX tumour models. We found that in vivo, giving rise to xenograft tumour formation. As high failure rates in some histologic subtypes of PDX tumour models have been reportedp = 0.001), which is supportive of this possibility. According to a recent study of the molecular characteristics for gastric cancer, mesenchymal-like gastric cancer comprised mostly (80.4%) of the diffuse type, by the Lauren classification, has the worst prognosisTumour aggressiveness involving metastatic tumours, lymph node metastases, and poorly differentiated histology has been reported to be related to engraftment success for colon cancer2729H. pylori-related gastritis is associated with gastric cancerp = 0.787). Furthermore, 55.6% of the engraftment successes for NOG mice involved lymphoma, and the growth rate of the tumour was not different between NOG and nude strains in our series  of Yonsei University Severance Hospital (4-2013-0526), and all patients provided written informed consent. All protocols adhered to the tenets of the Declaration of Helsinki. The samples were obtained from patients with pathologically proven adenocarcinoma of the stomach, with the following characteristics: 1) the size of the tumour was larger than 4 cm, because it should be large enough not to affect the pathological staging of the patient, 2) not only primary gastric cancer but also cancer in the remnant stomach was used; patients who were treated preoperatively with chemotherapy or chemoradiation therapy were also included, 3) if the patient received gastrectomy with metastasectomy for a metastatic lesion, both primary and metastatic tissue were obtained, and 4) patients with human immunodeficiency virus, hepatitis B, and/or hepatitis C virus were excluded.The tumour was obtained from a surgical specimen (F0) just after gastrectomy. A total of six pieces of tumour tissue were collected from each patient under sterile conditions. They were separated into two groups (three paired tissues in both groups): one group for the PDX tumour model in nude mice and another group for the PDX tumour model in NOG mice. In each group, there were three paired tissues: 1) tissue for the PDX tumour model was placed into RPMI 1640 medium with antibiotics ; 2) other tissue was cryopreserved in liquid nitrogen and stored at −80 °C; and 3) other tissue was fixed in 10% formalin solution for hematoxylin and eosin (H & E) staining as a representative histopathological characterisation of the implanted tumour. Each time point, such as the time of last ligation of the main artery, gastrectomy, and the beginning and completion of the PDX, was recorded to analyse the effect of processing time on engraftment success of the PDX tumour.3 fragments. Typically, each fragment was implanted into a subcutaneous area in the right and left flanks. They were also implanted into the subrenal capsule  from the 16th PDX case, because it was reported that subrenal capsule implantation shortened time to engraftment and improved the engraftment success18th PDX case and multiple pieces of tumours (4 ~ 6 pieces of 3 × 3 × 3 mm3 fragments) were tried from the 39th PDX case and the number of pieces were decided according to the size of the donor tumours. The size of the implanted tumour was checked 1 ~ 3 times per week using Vernier calipers when the implanted tissue was palpable, and the volume was calculated as (length × width2)/2. For follow-up of subrenal capsule PDX model tumours, non-enhanced magnetic resonance imaging (MRI) [Bruker Preclinical Animal MRI (9.4 T)] was used at 1–2 month intervals. Tumour formation in the implanted site over 500 mm3 in size was considered as engraftment success in the case of subcutaneous implantation, and tumour formation growth (detected by MRI) was regarded as successful for subrenal implantation. For the engraftment success cases, the mouse was anaesthetised and the tumour (F1) was removed for serial transplantation to the next generation . After removing the tumour, the mouse was sacrificed by cervical dislocation and necropsy was done to determine possible tumour metastasis.The mice were cared according to the institutional guidelines for animal care. All animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of the Yonsei University College of Medicine 2014-0130). The 6-week-old female athymic nude mice  and male NOG mice  were used for each PDX model. Before the experiments, the animals were acclimated for seven days with 12 hour light-dark cycles. The transferred tumour was placed into a sterile Petri dish containing phosphate-buffered saline (PBS), then sliced into 3 × 3 × 3 mm0. The 6-in situ hybridization (EBER ISH). IHC was performed using a Ventana XT automated stainer  with antibodies against CK , CD3 , and CD20 . Every other week, there was a regular meeting with the surgeon, the pathologist, and researchers for reviewing and discussion of the histopathological characteristics of each tumour.Sections (4 μm thick) from formalin-fixed and paraffin-embedded blocks were prepared for IHC and Epstein-Barr encoded RNA th edition of the UICCex vivo time (from gastrectomy to beginning of the PDX), the PDX time (from beginning to end of the PDX), and overall procedure time (ischemic time + ex vivo time + the PDX time), strain of mouse, amount of tumour and its implantation site, and whether Matrigel was used for analysis.Clinical and pathological information about enrolled patients was collected prospectively. The following variables were analysed to identify factors which were related to engraftment success of the PDX tumour model: 1) the patient’s age, patient’s sex, history of diabetes mellitus, history of hypertension, history of tuberculosis, history of smoking and alcohol, blood type, preoperative tumour markers [CEA and carbohydrate antigen (CA) 19-9], white blood cell count, percentage of neutrophils and lymphocytes, neutrophil lymphocyte ratio (NLR), and albumin level; 2) tumour pathological characteristics including size, location, gross type, tumour depth, presence of lymph node metastasis, and pTNM stage according to the 7For genomic analyses, two representative cases (GA006 and GA013) were selected considering two criteria: 1) PDX cases passaged greater than F3 generation at the time of analysis, 2) PDX cases representing early and advanced stage of tumours because they might have different genomic landscapes.® dsDNA Assay . For whole exome sequencing, SureSelect sequencing libraries were prepared according to the manufacturer’s instructions  using the Bravo automated liquid handler. For RNA sequencing, library preparations were performed using the Illumina™ Truseq RNA Access Library Prep Kit  according to manufacturer’s protocols. The library qualities of both whole exome and RNA sequencing were verified by capillary electrophoresis . After qPCR using the SYBR Green PCR Master Mix , index-tagged libraries were combined in equimolar amounts in the pool. Cluster generation occurred in the flow cell on the cBot automated cluster generation system (Illumina™). The flow cell loaded on the HISEQ 2500 sequencing system (Illumina™) performed sequencing with 2 × 100 base pair (bp) read lengths.Genomic DNA and total RNA were extracted from the frozen tissues of primary and PDX tumour model tissues using the DNeasy Blood and Tissue Kit  and the RNeasy Plus Mini Kit (Qiagen) according to the manufacture’s protocols. The quality of DNA was checked by 1% agarose gel electrophoresis and by the PicoGreenp-value less than 0.05 was considered statistically significant. The analyses were performed by SPSS, version 19.0 software for Windows . A total of 727 cancer-related genes .


The pericardium is one of the serosal cavities of the mammals. It consists of two anatomical structures closely connected, an external sac of fibrous connective tissue, that is called fibrous pericardium and an internal that is called serous pericardium coating the internal surface of the fibrous pericardium  and the heart  forming the pericardial space. Between these two layers a small amount of fluid exists that is called pericardial fluid. The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly. Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics. Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated. The pericardium is one of the serosal cavities of mammals , are responsible for the blood supply of the whole pericardium while the venous drainage is accomplished through the venae pericardiales which drain to the azygos vein, to the superior vena cava or to the brachiocephalic  D'Avila, . The serThe parietal lamina of the serous pericardium is composed of a monolayer of flattened, squamous-like, mesothelial cells. Mesothelial cells rest on a thin basement membrane supported by connective tissue stroma in a narrow submesothelial space. The connective tissue stroma contains variously oriented layers of collagen fibrils and small elastic fibers , which connect the pericardial cavity with the adjacent mediastinal pleural cavities, except the positions that are held by the adipose tissue , glanulocytes (31%), macrophages (12%), eosinophils (1.7%), and basophils (1.2%). This means that the pericardial fluid “lymphocytosis” should always be under critical consideration and characterized as pathological only when it exceeds 60% of the whole cell population  of Na+ (150.5 ± 0.72), Cl− (123.2 ± 0.71), Ca2+ (1.92 ± 0.04), and Mg2+ (0.85 ± 0.09) were lower in the pericardial fluid than in the plasma. On the contrary, the concentration of K+ (3.81 ± 0.07) was higher than the plasma, which was attributed to the K+ leakage from the myocardial interstitium toward the pericardial cavity, during systole  lubricating the moving surfaces of the heart, (2) stabilizing the heart anatomic position, (3) isolating the heart from the adjacent anatomical structures, prohibiting the adhesion formation, the inflammatory or neoplastic extention, (4) limiting heart dilatation during diastole, reducing the endomyocardial tension, (5) preventing cardiac hypertrophy in pressure overload conditions, (6) reducing the right ventricular impulse work in left ventricular overload conditions, (7) the ventriculoatrial blood retrogression prevention during high end-diastolic ventricular pressures, (8) the preservation of the negative endothoracic pressure, which is crucial for the atria blood filling, (9) the nervous stimulation response and regulation of the cardiac frequency and arterial blood pressure, (10) the formation of a hydrostatic compensation system ensuring that end-diastolic pressure remains the same at all hydrostatic levels and the Frank–Starling mechanism is functional Holt, .In vitro studies in canine parietal pericardium demonstrated the presence of viscoelastic response, mainly attributed to the presence and the arrangement of the elastic and collagen fibers  have shown the same mechanical properties, only with quantitative differences. In vitro epicardial studies , proved the presence of elastic properties that have been attributed to the composition and orientation of the connective tissue. Specifically, the human epicardium undergoes an oblong and circumferential systolic shortening, therebe the energy gathering during the diastolic period may contribute to the passive mechanical properties of the myocardium  and pericardial cavity (p), respectively. L is a membrane conductance constant for liquids, S is the surface area and σ is the osmotic constant of the endothelium/interstitial tissue barrier for proteins  as well as the sac deformation that provoved by the catheter insertion. The Pp depends on the pericardial fluid volume and accumulation velocity, the cardiac and respiration circle phase and the measurement position. The large amount and the fluid rapid accumulation results in rapid and great increase in Pp. This is not present during the gradual fluid accumulation, which allows greater ammounts of fluid without hemodynamic instability. This phenomenon is due to the viscoelastic properties of the parietal pericardium  , during the enddiastole  through “small” pores and later it was shown that there is a passive paracellular diffusion of macromolecules  through “large” pores (either like permanent channels or like transient cystic formations). In both cases the main morphological and functional barrier proved to be the mesothelium. However, by that time active ion trasport through the parietal pericardium was thought to be minimal  compared to the underlying connective tissue alone (1 ± 0.2 Ω × cm2) , is independent from its concentration. This finding contradicted the previous data regarding rabbit pericardium, pleura and omentum where the reference values were higher and directly proportional to albumin concentration  (Vogiatzidis et al., Variance among species seems to be the case also in terms of transmesothelial electrical resistance, an index of ion transport. As mentioned above rabbit parietal pericardium had values in the range of 10.1 ± 0.9 Ω × cmThe study of pericardial space physiology is an area with many things to be discovered. The mechanism of pericardial fluid production is straightforward in physiological conditions, however it needs to be identified what is the exact role of the mesothelial cells both in the recycling of the pericardial fluid as well as with respect to the paracrine function that they possess. Another important challenge would be to dissect the exact contribution and magnitude of each mechanism regulating the recycling of the pericardial fluid. Finally, few things are known about the interplay of mesothelial cells and pericardial fluid. These areas will increase our understanding of the physiology of the pericardial space once explored as well as they will provide us with new insights regarding drug development in the context of pericardial effusions.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The affiliation for the second author is incorrect. Björn Halleröd is affiliated with: Department of Sociology and Work Science, University of Gothenburg, Gothenburg, Sweden.In the Funding section, the grant number from the funder Swedish Research Council is not listed. The grant number is: (dnr: 2011–7619).


Predicting fluid responsiveness is of paramount importance to avoid unnecessary fluid administration in ARDS patients, since a positive fluid balance is associated with ARDS mortality . Several-1 predicted body weight (PBW).To evaluate the diagnostic performance of three methods to predict fluid responsiveness in PP: cardiac index variation during the Trendelenburg position and an end-expiratory occlusion, and pulse pressure variation after increasing tidal volume (VT) to 8 ml.kg-1 PBW, during a 15-s end-expiratory occlusion and after IV infusion of 500 ml crystalloids. Patients were returned to baseline settings after each intervention. Fluid responsiveness was deemed present if cardiac index assessed by thermodilution increased by at least 15% after fluid administration.This study is a prospective single-center study, performed on ARDS patients in PP, monitored with the PiCCO device, and with acute circulatory failure. Patients were studied at baseline with bed angulation 13°, during a 1-min postural change in the Trendelenburg position with bed angulation -13°, during a 1 min increase of VT to 8 ml.kg-1 PBW, PaO2/FiO2 ratio 158 mm Hg (116-201), PEEP 8 (6-10) cm H2O, and plateau pressure 23 (20-27) cm H2O. 7 patients (37%) were deemed fluid-responsive after fluid administration. The area under ROC curve of the pulse contour derived cardiac index during the Trendelenburg maneuver and the end-expiratory occlusion test were 0.91 (95% CI: 0.77-1) and 0.45 (95% CI: 0.17-0.73), respectively. An increase in cardiac index ≥ 8% during the Trendelenburg maneuver enable to diagnose fluid responsiveness with a sensitivity of 71% (95% CI: 43-100%), and a specificity of 100% (95% CI: 100-100%). Cardiac arrhythmia were present at baseline in 11 patients (58%), which were therefore excluded from pulse pressure variation analysis. The area under ROC curve of pulse pressure variation during VT increase to 8 ml.kg-1PBW was 0.50 (95% CI: 0.04-0.96).19 patients (SAPS II 56 (48-62)) were included at the time of abstract submission. VT was 6.0 (5.9-6.2) ml.kgCardiac output measurement during a Trendelenburg maneuver is a reliable method to assess fluid responsiveness in ARDS patients in the prone position.Clinical trial registered with www.clinicaltrials.gov (NCT01965574).


She had received the VZV vaccination when she was 5-years-old and had not been exposed to chicken pox before the LDLT, and her serum was positive for VZV immunoglobulin G at the time of the LDLT. Although she underwent treatment with intravenous acyclovir, intravenous immunoglobulin, and withdrawal of immunosuppressants, her symptoms worsened and were accompanied by disseminated intravascular coagulation, pneumonia, and encephalitis. These complications required treatment in the intensive care unit for 16 days. Five weeks later, her clinical findings improved, although her VZV-DNA levels remained high (8.5 × 103copies/mL). Oral acyclovir was added for 2 weeks, and she was eventually discharged from our hospital on day 86 after admission; she has not experienced a recurrence. In conclusion, although disseminated VZV infection with multiple organ failure after pediatric LDLT is a life-threatening disease, it can be cured via an early diagnosis and intensive treatment.A 12-year-old female patient with biliary atresia underwent living donor liver transplantation (LDLT). Twelve months after the LDLT, she developed acute hepatitis  and was diagnosed with disseminated varicella-zoster virus (VZV) infection with high level of serum VZV-DNA (1.5 × 10 Varicella-zoster virus (VZV) is a DNA virus that belongs to the family of herpes viruses, and is the cause of both chicken pox (as a primary infection) and herpes zoster, which is a reactivation infection that is typically observed in adults. Chicken pox is generally a mild disease, VZV infection is known to be more severe in adolescent patients, and although disseminated VZV infection is a rare disease, it is potentially life-threating in patients with immunosuppression after organ transplantation –4. We haA 12-year-old female patient with biliary atresia underwent LDLT using a left lobe graft from her ABO-compatible father. She had received the VZV vaccination when she was 5-years-old and she had not been exposed to chicken pox before the LDLT. Her serum was positive for VZV immunoglobulin G (IgG)  at the time of the LDLT. The recipients’ cytomegalovirus (CMV) status was seronegative (IgG-negative and IgM-negative) before the LDLT, although the donor’s CMV status was seropositive . Her immunosuppression regimen after LDLT consisted of tacrolimus (FK), methylprednisolone (MP), and mycophenolate mofetil (MMF). She did not receive prophylactic therapy for CMV infection, and was evaluated each month for CMV antigenemia (C7-HRP) .5 copies/mL). As we could not investigate the strain type of the VZV, we were unable to determine whether her infection was primary infection or secondary dissemination. In addition, she exhibited signs of severe hepatic damage  and disseminated intravascular coagulation (DIC)  Table . We cons3), due to bone marrow suppression. On day 12, she experienced a generalized tonic-clonic seizure. Although brain magnetic resonance imaging did not reveal any abnormal findings, we suspected encephalitis due to disseminated VZV infection and considered performing a lumbar puncture, although we chose not to perform the puncture, based on her unresolved bleeding tendency. Therefore, she remained in the intensive care unit for 16 days, and as her symptoms gradually improved, we resumed the oral immunosuppressants (FK and MP) after 12 days of cessation. In addition, on day 16, we changed the intravenous acyclovir to intravenous ganciclovir (12.5 mg/kg/day), because she had developed a CMV infection . After 14 days of intravenous ganciclovir, we changed the treatment to oral valganciclovir after we had confirmed the absence of CMV antigen. At 5 weeks after these treatments were started, all of her skin rash was covered with scabs, her organ symptoms had disappeared, and her clinical findings appeared to be completely improved, although her VZV-DNA levels remained high (8.5 × 103 copies/mL). We continued the oral acyclovir treatment for another 2 weeks, and she was discharged on day 86 after the admission; she has not experienced a recurrence. She was well at 6 months after discharge, and follow-up PCR testing did not reveal any VZV-DNA.Although she underwent treatment with intravenous acyclovir (30 mg/kg/day), intravenous immunoglobulin (125 mg/kg/day), and withdrawal of all immunosuppressants , her symptoms worsened, and she developed pneumonia that required artificial respiratory management for 11 days . Although it is unknown whether the present case was primary infection or re-activation of the vaccine strain, it is possible that re-activation of the vaccine strain might have led to severe disseminated VZV infection –27. Pati3copies/mL), even after all skin rashes and organ symptoms had completely resolved. Therefore, we added prophylactic oral acyclovir and continued monitoring until a decrease in the patient’s VZV-DNA was observed without any symptoms. This course appears to have been effective, as the patient has not experienced a recurrence. Similarly, monitoring for Epstein Barr virus DNA via PCR is and established method for prophylaxis and management of those infections, which are also common after liver transplantation [The primary treatment for disseminated VZV infection with MOF should address the organ failure and involve antiviral therapy, including intravenous acyclovir. In general, the antiviral therapy should be continued until all skin rashes are covered with scabs, and the organ symptoms have disappeared. Interestingly, Kronenberg et al. have reported four cases of disseminated VZV infection after solid organ transplantation in which the VZV-DNA levels were monitored via PCR . Among tantation , 30. HowIn conclusion, although disseminated VZV infection with MOF after pediatric LDLT is a life-threatening disease, it can be cured via an early diagnosis and intensive treatment. In these cases, PCR monitoring of VZV-DNA is helpful to quickly reach an accurate diagnosis and evaluate the efficacy of the subsequent treatment.Written informed consent was obtained from the patient and her parents for publication of this case report and the accompanying images. A copy of the written consent is available for review by the Editor-in-Chief.This study was approved by Ethics Committee of Jichi Medical University (rA15-042).


Both vaccines contain the live-attenuated Oka strain of VZV. Although highly immunogenic, a two-dose regimen is required to achieve a 99% seroconversion rate. Zostavax vaccination reduces the incidence of HZ by 51% within a 3-year period, but a significant reduction in vaccine-induced immunity is observed within the first year after vaccination. Developing more efficacious vaccines and therapeutics requires a better understanding of the host response to VZV. These studies have been hampered by the scarcity of animal models that recapitulate all aspects of VZV infections in humans. In this review, we describe different animal models of VZV infection as well as an alternative animal model that leverages the infection of Old World macaques with the highly related simian varicella virus (SVV) and discuss their contributions to our understanding of pathogenesis and immunity during VZV infection. Primary infection with varicella zoster virus (VZV) results in varicella (chickenpox) followed by the establishment of latency in sensory ganglia. Declining T cell immunity due to aging or immune suppressive treatments can lead to VZV reactivation and the development of herpes zoster . HZ is often associated with significant morbidity and occasionally mortality in elderly and immune compromised patients. There are currently two FDA-approved vaccines for the prevention of VZV: Varivax Varicellovirus genus, and the causative agent of varicella (chickenpox) and herpes zoster . Like other members of the alphaherpesvirus subfamily, VZV establishes a latent infection in sensory ganglia [Varicella zoster virus (VZV) is a neurotropic alphaherpesvirus of the  ganglia . The str ganglia . The cor ganglia . The uns ganglia . The env ganglia . The VZV ganglia . VZV enc ganglia  and vira ganglia . in vitro infectivity data [ex vivo analysis during VZV infection, the exact mode of VZV trafficking remains unknown. There is strong clinical evidence that primary VZV infection occurs through the inhalation of virus-laden respiratory droplets ,9 or airity data ,19,20 asity data . In the It is unclear how or when VZV travels to the ganglia following primary infection, but two hypotheses exist. The first proposes that the sensory nerves of the dorsal root terminating within the dermis become infected either by the release of cell-free virus following epidermal infection or due to the cell-to-cell fusion of infected cells with neuronal axons ,22. The http://www.cdc.gov/shingles/hcp/clinical-overview.html). HZ begins with a prodromal phase characterized by pain, itching, or burning sensations in one to three dermatomes [VZV reactivation typically presents as herpes zoster (HZ), although it can be asymptomatic at times as has been documented in astronauts during and shortly after spaceflight ,25, and rmatomes . In mostrmatomes  that usurmatomes . Althougrmatomes . The mosrmatomes . Other crmatomes , vertigormatomes , as wellrmatomes . Asymptormatomes ,35,36.There are currently two FDA-approved VZV vaccines, both of which contain the live-attenuated Oka strain of VZV: Varivax, for the prevention of varicella, and Zostavax, for the prevention of HZ. While Varivax contains on average 1350 plaque-forming units (PFU) per 0.5 mL of vaccine, Zostavax has a minimal potency of 19,400 PFU . VarivaxSuccessful infection of guinea pigs with VZV only occurs with the use of a guinea pig-adapted strain , which iVZV infection of mice or rats via subcutaneous, ocular, and intraperitoneal routes results in seroconversion without clinical disease ,57,58,59A rat model of VZV-associated pain has been developed in order to gain a better understanding of post herpetic neuralgia (PHN). In this model, Wistar rats are inoculated subcutaneously in the footpad and then subjected to behavioral tests that include measurement of paw withdrawal time in response to mechanical or thermal stimuli . These sTo circumvent some of the host specificity constraints of VZV, Dr. Arvin and colleagues applied the severe-combined immunodeficient (SCID)-humanized (SCID-hu) mouse model to the study of VZV pathogenesis . In thisin vitro studies that demonstrated high infectivity of tonsillar T cells by VZV [The infection of thy/liv implants directly inoculated with a suspension of VZV-infected cells revealed that both CD4 and CD8 T cells support VZV replication as evidenced by the presence of both viral DNA and infectious virus . These os by VZV . In addis by VZV , suggestvivo. For example, while previous in vitro studies have indicated that ORFs 14, 47, and 66 are dispensable for viral replication  [69,70,ectively ,72, dataectively . The SCIectively . HoweverThe SCID-hu mouse model has also been adapted to study VZV neurotropism by implanting a human fetal dorsal root ganglia (DRG) under the kidney capsule . The dirSeveral reports have documented naturally acquired varicella in anthropoid apes ,79. In oPlatyrrhini, e.g., marmosets, spider monkeys) or Old World  [Homo sapiens, and it is estimated that New World monkeys diverged over 35 million years ago whereas Old World monkeys diverged 10–12 million years ago [Callithrix jacchus) via combined oral-nasal-conjunctival route resulted in seroconversion, no varicella, and an inability to detected viral replication [Erythrocebus patas) leads to seroconversion in the absence of clinical disease or viral replication [There were also several attempts to experimentally inoculate monkeys with VZV, but none resulted in clinical disease. In general, monkeys can be categorized as New World (acaques) . New Worears ago . VZV inolication . Similarlication . Both oflication . VZV DNAlication . These dRecords indicate the first outbreak of a varicella-like disease in nonhuman primates in 1967 . Since tErythrocebus patas) is a ground-dwelling species of Old World monkey that inhabits open grasslands of Central Africa. It is the only member of the Erythrocebus genus, but recent phylogenetic evidence indicates that it is the closest relative of the vervet monkey (Chlorocebus aethiops). Historical records report that natural infection of patas monkeys with SVV results in severe, disseminated disease with a 50% fatality rate [The patas monkey  is native to Southeast Asia. There are 10 subspecies of Macaca fascicularis, and the one most often used in research is commonly referred to as the crab-eating macaque. Initial outbreaks of SVV at the Washington Primate Center between 1969 and 1971 resulted in a total of four deaths and 50 diseased animals out of 184 cynomolgus monkeys at risk [4 PFU SVV. This approach results in the development of varicella rash 10–14 days post-infection and the establishment of latency [The cynomolgus monkey , grivet (C. aethiops), and vervet (C. pygerythrus) monkey. SVV outbreaks in C. aethiops at the Liverpool School of Tropical Medicine (UK) (1966) resulted in nine deaths out of the 17 animals at risk [C. aethiops that exhibited clinical disease [C. aethiops that is reminiscent of fatal human VZV infection in immunodeficient patients has been reported [C. aethiops [ at risk . An outb disease . Severe reported . Interesaethiops . Experimaethiops . Moreoveaethiops . To addraethiops . Naturalaethiops . In addiaethiops . Studiesne (UK) 16 resulteaethiops . HoweverMacaca mulatta), also called rhesus monkeys, are Old World monkeys native to northern India, Bangladesh, Pakistan, Nepal, Burma, Thailand, Afghanistan, Vietnam, and southern China. Rhesus macaques have been used in numerous clinical and laboratory investigations, including the evaluation of several vaccines and antivirals. The first documentation of a mild exanthematous disease in rhesus macaques was in May 1969 at the Washington Regional Primate Research Center  [versus intratracheal) could also influence development of disease.Rhesus macaques  . Nineteetle, WA) . Experimtle, WA) . Intratrtle, WA) . The lactle, WA) ,124. Difin vivo during SVV infection [in vivo.Analysis of viral transcription levels during acute and latent SVV infection in young rhesus macaques shows that all known SVV ORFs are expressed to detectable levels in bronchial alveolar lavage samples . Moreovenfection . Infectinfection . Moreovenfection . These dAn interesting study showed that nonmyeloablative-TBI of a cohort of rhesus macaques resulted in severe disseminated varicella in one of the animals, similar to what is observed with immune compromised persons infected with VZV . FurtherGiven the clinical, virological, and immunological similarities between SVV infection of rhesus macaques and VZV infection of humans, this animal model will undoubtedly yield critical insights into VZV pathogenesis and host response.Our understanding of VZV biology has increased substantially since it was first discovered over a century ago. However, due to the strict host-specificity of infection and cell-associated nature, our knowledge of host-pathogen interaction regarding VZV infection remains incomplete. Numerous efforts have been made to develop adequate animal models of VZV infection, but these models remain limited. Nevertheless, the ability of VZV to establish latency in sensory ganglia of these animals offers an opportunity to identify viral genes that are critical to the establishment and/or maintenance of viral latency. The rhesus macaque model of SVV infection recapitulates key clinical and virological features of VZV infection. Specifically, immune competent rhesus macaques develop a benign disease that closely resembles chickenpox, develop a immune response with similar kinetics to what is observed in VZV infection in children, and acute infection is resolved concurrent with the established latency in sensory ganglia. Therefore, data generated using this model will contribute to our understanding of pathogenesis and host response during VZV infection.et al., study above are more in line with those observed in humans receiving bone marrow ablating TBI for autologous bone marrow transplantation where the rates of HZ are 77–84% HZ [versus 1:15800 in experimentally SVV inoculated rhesus macaques and 1:9400 in VZV infected humans) [versus humoral immunity in the prevention of HZ can be evaluated. One of the most important aspects in the development of an ideal animal model of VZV infection is reactivation, which has not yet been experimentally induced in the rhesus macaque model. Reactivation has been observed in both cynomolgus and African green monkeys receiving nonmyeloablative-TBI that did not ablate bone marrow and/or treated with immune suppressants ,111. Ind7–84% HZ ,131. One humans) ,133. ThuAnother area that remains poorly understood is the VZV transcriptional profile during latency. Several studies have investigated VZV transcription in latently infected human sensory ganglia using various methods including quantitative RT-PCR, in-situ hybridization, cDNA libraries and northern blot hybridization. Transcripts associated with VZV ORFs 4, 21, 29, 62, 63, and 66 are detected most often ,137,138.in vivo. An animal model that can mimic hallmarks of varicella and zoster using VZV would be of tremendous value to the field and would greatly advance the development of more efficacious second-generation vaccines and antivirals against VZV.Efforts towards developing an animal model wherein VZV can cause clinical disease should also continue. These efforts will most likely require adapting VZV to growing in cells derived from rhesus macaques including potentially passaging the virus


Giant cell tumour is a benign aggressive bone tumour. Most commonly, it is seen in epiphysiometaphyseal region around knee and distal radius. Proximal ulna is a rare location for giant cell tumour. According to reports, only 4 such cases have been reported in English literature. We report one such case of giant cell tumour of proximal ulna. Patient presented with painless, progressiveswelling around right elbow since 4 months. Proximal ulna along with tumour was resected and elbow was reconstructed using nonvascularized free fibular graft. At two years of follow-up, patient is tumour-free and has functional range of movement in elbow. We are reporting the case because of its rare location and for the indigenous treatment modality of using free fibular graft for elbow reconstruction. Giant cell tumour also known as osteoclastoma is a benign aggressive tumour. It has a slight female preponderance and is seen in the age group of 20–40 years. Giant cell tumour is an epiphysiometaphysial tumour commonly seen in distal end of femur, proximal end of tibia, and distal end of radius .Treatment options include curettage with or without bone grafting, extended curettage, wide excision, and reconstruction.We are reporting a case of giant cell tumour of proximal ulna. According to reports, only few such cases have been reported in English literature. After evaluation, tumour was resected en bloc and joint was reconstructed using free fibular graft. This case is being reported for its rare location and the indigenous treatment modality carried out.A 30-year-old male presented with painless swelling around his right elbow since 4 months . It was On examination, a localised swelling measuring 5 × 6 cm in posterior aspect of elbow was seen which was nontender, hard in consistency, and continuous with proximal ulna. The overlying skin was normal. Elbow flexion was up to 90 degrees and terminal 10 degrees of extension were limited.X-ray showed a lytic lesion involving entire proximal ulna with soap bubble appearance with destruction of articular surface . FNAC waGiving a tumour-free upper limb along with a functional elbow joint was a challenging part. Hence, treatment plan included en bloc excision of proximal ulna with tumour and safe margin of normal appearing bone and reconstruction of the elbow joint using free fibular graft.Under general anaesthesia, tumour was exposed through posterior approach to elbow . ProximaPost-op period was uneventful. K-wire was removed after 3 weeks and elbow was mobilised. Patient was regularly followed up for 2 years for radiological union of the graft, functional outcome of the elbow, and possible recurrence or metastasis to lungs.Radiological union of the graft was seen as early as 4 months. At the end of 2 years, patient is pain-free and has a stable and functional elbow . No recuGiant cell tumour is a benign bone tumour but has an aggressive course. It is seen after skeletal maturity with slight female preponderance. Epiphysiometaphysical region around knee and distal end radius are the favoured sites . Very feFirst case of giant cell tumour of proximal ulna in South East Asia was reported by Sanjay et al. in 1991 . And sinUsual management of this tumour involves resection of the tumour or curettage and ablation of the cavity surface. This is feasible if the tumour is located in a long bone. In a small bone, excision and reconstruction are preferred. The challenge we faced was that the tumour involved proximal part of ulna along with elbow joint of the dominant upper limb of the patient. Hence, it was necessary for us to keep the bone and elbow joint-free from tumour and give the patient a stable, functional elbow joint. In previous reported cases, excision of proximal ulna along with arthrodesis of elbow in functional position has been done , 3. We pFree fibular grafts have been used frequently in orthopaedics as a graft to bridge long bony gaps and in very few cases to reconstruct joints. There have been reports of them being used to reconstruct elbow joint after resection of distal end of humerus –6. But rIn summary, we were able to perform a limb saving procedure along with giving a stable functional joint using a free fibular graft. However, further follow-up and more research are needed in this regard to carry out this procedure as a regular treatment modality for tumours around elbow.


S-nitrosoglutathione (GSNO) is a nitric oxide (NO) donor, which exerts antioxidant, anti-inflammatory, and microbicidal actions. Intragingival application of GSNO was already shown to decrease alveolar bone loss, inflammation and oxidative stress in an experimental periodontal disease (EPD) model. In the present study, we evaluated the potential therapeutic effect of topical applications of hydroxypropylmethylcellulose (HPMC)/GSNO solutions on EPD in Wistar rats. EPD was induced by placing a sterilized nylon (3.0) thread ligature around the cervix of the second left upper molar of the animals, which received topical applications of a HPMC solutions containing GSNO 2 or 10 mM or vehicle (HPMC solution), 1 h prior to the placement of the ligature and then twice daily until sacrifice on day 11. Treatment with HPMC/GSNO 10 mM solution significantly reduced alveolar bone loss, oxidative stress and TNF-α e IL-1β levels in the surrounding gingival tissue, and led to a decreased transcription of RANK and TNF-α genes and elevated bone alkaline phosphatase, compared to the HPMC group. In conclusion, topical application of HPMC/GSNO solution is a potential treatment to reduce inflammation and bone loss in periodontal disease. Periodontal diseases, including gingivitis, are highly prevalent  and charEndogenously produced nitric oxide (NO) is a mediator of several physiological and pathophysiological processes whose actions include the inactivation of ROS and the blocking of radical propagation reactions ,6. It hain vivo in a animal model of periodontitis [in vitro with L-arginine supplementation [It has been demonstrated that intragingival administration of S-nitrosoglutathione (GSNO), an endogenously found NO carrier and donor decreases bone resorption dontitis , similarentation . GSNO haentation –18 as weentation  in sever2), phosphate-buffered saline (PBS) pH 7.4, acetone and hydrochloric acid (HCl) were purchased from Sigma-Aldrich . All reagents were analytical grade and used as received. All experiments were performed using deionized water from a Millipore Milli-Q gradient filtration system .Hydroxypropylmethylcellulose , glutathione (GSH), sodium nitrite  as described elsewhere [S-nitrosoglutathione (GSNO) was synthesized by reacting GSH with NaNOlsewhere . Solid, To incorporate GSNO in the HPMC solutions at final concentrations of 2.0 mM (HPMC/GSNO 2.0 mM) and 10 mM (HPMC/GSNO 10 mM), appropriate amounts of solid GSNO were weighted and transferred initially to PBS solution in falcon tubes. After complete GSNO dissolution under stirring, appropriate volumes of the GSNO solutions were transferred to other falcon tubes containing solid HPMC in amounts calculated to obtain a final HPMC concentration of 1.25 wt% in all cases. The tubes were stirred for 5 min in a vortex and transferred to a refrigerator at 8°C, where they stayed for 2 h to assure complete dissolution of the HPMC in the GSNO solutions. The GSNO solutions and HPMC/GSNO solutions were protected from room light with aluminum foil during all the procedures in order to avoid GSNO photodecomposition. The prepared formulations were used immediately in the topical applications and stored back in the refrigerator after use. The formulations were discarded after 3 days of storage.ad libitum. Surgical procedures and animal treatments were conducted in accordance with the guidelines of the Animal Research Ethics Committee , of the Federal University of Ceará, Brazil, who approved all the procedures involving the animals. All efforts were made to minimize suffering.Male Wistar rats from the Federal University of Ceará, weighting 200 to 250 g were housed in temperature-controlled rooms under 12 hour light-dark cycles and received water and food th.Experimental Periodontal Disease (EPD) was induced as previously described –21.Briefth day. Control groups consisted of animals subjected to the surgical procedure that received only the vehicle (HPMC) and a group of animals not subjected to experimental periodontitis .The animals were divided into groups of 6 animals each and received topical applications of HPMC/GSNO 2.0 mM or HPMC/GSNO 10.0 mM. The solutions were applied using small cotton swabs with a gentle massage to both palatal and vestibular sides of the left maxillary molars gingiva, starting 1 hour before the placement of the ligature and twice daily until euthanasia on the 112) corresponding to the exposed roots of the molars  was calculated and subtracted from the corresponding area (mm2) of the normal group. All acquired images were compared to a well-known area (1.0 x 1.0 mm2).The animals were euthanized 11 days after the placement of the ligature and the maxillae were excided and fixed in 10% buffer formalin. After 24 hour, the left maxillae were defleshed and stained with methylene blue (1%) to differentiate bone from teeth, fixed in a piece of wax and photographed. The digital images were subjected to alveolar bone loss analysis using the Image J software, as described previously . In thisFor the histopathological analysis, the maxillae were excised, fixed in 10% neutral-buffered formalin and demineralized in EDTA. The specimens were then dehydrated, embedded in paraffin, and sectioned along the molars in a mesiodistal plane for hematoxylin and eosin staining. Three sections of 4 μm each, corresponding to the area between the first and second molars were evaluated under light microscopy using a 0 to 3 score grade ,23, as fth day in order to obtain plasma concentration of alkaline phosphatase using the thermo-activation method, as previously described [®, Lagoa Santa, MG, Brazil). The results were expressed as Bone Alkaline Phosphatase variation on day 11 (U/L) compared to the values obtained before the EPD induction, on day 0.Blood samples were collected from retro-orbital plexus, under anesthesia with a mixture of ketamine and xylazine , before ligature (on day 0) and immediately before the euthanasia on the 11escribed . The sam3PO4 and 0.5 ml of 0.6% thiobarbituric acid aqueous solution and the mixture was stirred and heated in boiling water for 45 minutes. After cooling, 2 ml of n-butanol were added and the mixture was homogenized. The butanol layer was separated, and the difference between the optical densities at 535 and 520 nm was used for calculating the MDA concentrations, which were expressed as nanomol of MDA per gram of gingival tissue.To evaluate the effect of HPMC/GSNO solutions on the oxidative stress, reduced glutathione (GSH), an antioxidant and malonaldehyde, a marker for oxidative stress, were measured in the gingival tissue collected on day 11. Lipid peroxidation was measured as malonaldehyde (MDA) production through the thiobarbituric acid reaction  in the gTo evaluate the reduced glutathione (GSH) levels, the gingivae were first homogenized (400 μl of a 10 wt% tissue solution prepared in 0.02 M EDTA). After that, 320 μl of distilled water and 80 μL of 50% trichloroacetic acid (TCA) were added, followed by centrifugation at 3000 rpm for 15 min at 4°C. The supernatant was collected (400 mL) and added to 800 μL of 0.4 M Tris buffer at pH 8.9 and 20 μL of 0.01 M DTNB. The absorbance of each sample was measured at 412 nm, and the results were described as μg of GSH per milligram of tissue.X) quantification using the Griess method [On day 11 after EPD induction, the gingivae surrounding the upper left molars were removed for nitrite/nitrate  measurements. The quantification of the cytokines contained in the samples was performed using an enzyme-linked immunosorbent assay (ELISA), as previously described [The gingivae surrounding the upper left molars were removed on the 11escribed ,28. TNF-th day, the maxillae were excised, fixed in 10% neutral-buffered formalin and demineralized in 10% EDTA. The immunohistochemical for iNOS, RANK and TRAP were performed using the avidin–biotin–peroxidase method [After the animals were sacrificed on the 11e method ,28 in foe method .AurumTMTotal RNA Fatty and Fibrous Tissue Kit  following the manufacturer’s instructions. The quality of the RNA was analyzed by 260/280 ratio, and quantified by UV absorption using NanoDrop . One microgram of total RNA from the intestinal samples in a final volume of 20 μl were reverse-transcribed into cDNA in the C1000 Touch™ Termal Cycler system with the iScript™ cDNA synthesis kit from Bio-Rad. Real-time quantitative PCR analysis of the mRNA was performed in an CFX96 Touch™ real-time PCR detection system instrument from Bio-Rad using the iQTM SYBR® Green Supermix  as indicated by the manufacturer. qPCR was performed for 35 cycles under the following conditions: denaturation 95°C, 30 s; annealing 60°C, 30 s; extension, 25°C, 50 s. All samples were run in duplicate, and the relative mRNA expression level was determined after normalizing all values to those of GAPDH. All samples were evaluated for the dissociation characteristics of the double-stranded DNA during heating . The relative gene expression was determined using the 2-ΔΔCt method [Expression of mRNA for TNF-α, RANK, RANK-L and OPG was determined by quantitative real-time polymerase chain reaction (qPCR). RNA was extracted from gingival tissue using the Data are presented as means ± standard error (SEM) or as medians when appropriate. Univariate Analysis of Variance followed by Bonferroni test was used to compare means and Kruskal–Wallis and Dunn tests were used to compare medians. P< 0.05 was considered significant. All analyses were performed using GraphPad Prism 6 software, San Diego, CA, USA.Local administration of HPMC/GSNO 10 mM solution 1 hour before the placement of the ligature and twice daily for 11 days resulted in a significant inhibition of alveolar bone loss Figs , compareHistopathological analysis of the region between the first and second molars of the animal periodontium that received local applications of HPMC demonstrated accentuated inflammatory leukocyte infiltration, resorption of the alveolar bone and cementum and collagen fiber derangement within the periodontal ligament, receiving a median score and range of 3(2–3) ; Fig 2D.The treatment with GSNO/HPMC (2 and 10 mM) resulted in a significant increase in the BALP serum levels variation when compared with the control HPMC solution group .th day the group subjected to EPD that received topical applications of the control HPMC solution showed a significant increase in the MDA level and a reduction in the GSH concentration in the gingival tissue, when compared to the normal group. At the same time, treatment with GSNO/HPMC at 10 mM (but not 2.0 mM) significantly reduced the MDA gingival tissue levels  significantly reduced NOx concentration when compared with the control HPMC solution group .It was observed a significant increase in the TNF-α  and IL-1th day compared with the weak staining observed in the Normal control group  reduce inflammation and bone loss in EPD ,14. The S-S bond ,32. FreeIn the present HPMC/GSNO solutions the HPMC concentration is 1.25 wt%. At this concentration, the HPMC chains are considered to be fully hydrated, with little polymer-polymer interactions, comprising thus a viscous polymeric solution and not a hydrogel. HPMC solutions can undergo gelation with HPMC concentrations above 10 wt% and HPMC hydrogels are frequently used as vehicles for drug delivery ,34. The The observed therapeutic effect of the HPMC/GSNO 10 mM solution on the bone resorption was associated with an increase in the level of plasma bone alkaline phosphatase (BALP), a marker of osteoblastic activity, in the serum of animals and a considerable reduction in TRAP immunostaining . These changes were observed in the periodontal tissue of the animals treated with he HPMC/GSNO 10 mM solution for 11 days, when compared with the control HPMC solution group, suggesting that the HPMC/GSNO 10 mM solution prevents bone resorption and also induces bone formation. Accordingly, it has been described that NO donors have beneficial effects on the control of bone resorption (decreased osteoclast activity), and have a milder anabolic action on bone formation, enhancing osteoblast activity ,13.The present study suggests that the protective effect of GSNO on the alveolar bone resorption is at least in part due to its anti-inflammatory, anti-oxidant and immunomodulatory properties. We demonstrated that the HPMC/GSNO 10 mM solution significantly reduced the TNF-α mRNA in gingival tissue of animals treated with this formulation as well as the gingival levels of TNF-α and IL-1β, when compared with the control HPMC solution group.Cytokine participation in periodontal disease is well documented and these substances, particularly TNF-α and IL-1β, may amplify the inflammatory response causing tissue destruction and bone loss . It has The release of large amounts of NO by iNOS has been shown to play a major role in immune reactions and inflammatory processes, including rheumatoid arthritis and periodontal disease . NO reacConsidering that alveolar bone loss is a severe consequence of periodontal disease, we investigated the role of GSNO on bone regulatory RANK/RANKL/OPG pathway in association with inflammatory and oxidative factors was investigated. It has been demonstrated that TNF-α can lead to bone destruction by acting direct on osteoclast differentiation . TNF-α a


In silico modelling is demonstrated to considerably benefit from information obtainable with PET and PET/CT. In particular, models have successfully integrated tumour glucose metabolism, cell proliferation, and cell oxygenation from multiple tracers in order to simulate tumour behaviour. With the development of novel radiotracers to image additional tumour phenomena, such as pH and gene expression, the value of PET and PET/CT data for use in tumour models will continue to grow. In this work, the use of PET and PET/CT information in in silico tumour models is reviewed. The various parameters that can be obtained using PET and PET/CT are detailed, as well as the radiotracers that may be used for this purpose, their utility, and limitations. The biophysical measures used to quantify PET and PET/CT data are also described. Finally, a list of in silico models that incorporate PET and/or PET/CT data is provided and reviewed.The innovation of computational techniques serves as an important step toward optimized, patient-specific management of cancer. In particular,  Anatomic imaging modalities, particularly X-ray computed tomography (CT) and magnetic resonance imaging (MRI), have long been the standard tools for the accurate localization of organs and lesions in radiation oncology. Today, they play a routine role in three-dimensional treatment planning. However, the effectiveness of structural imaging techniques in determining metabolic or functional tissue information is limited. Functional imaging has been demonstrated to be invaluable for the initial diagnosis and staging of cancer as well as the monitoring of therapy and the detection of cancer recurrence . Metabol18F-fluorodeoxyglucose (FDG). FDG-PET has demonstrated superior accuracy over conventional imaging modalities in multiple scenarios across both the diagnosis and the staging of cancer [PET scanning has progressed into widespread clinical practice since its first commercialization in the late 1970s. For oncological PET studies, the most utilized and extensively researched radiotracer is f cancer , 4. In af cancer . HoweverIn order to take advantage of their inherent benefits, the combined use of both anatomic and physiologic imaging modalities is optimal. The accurate structure localization capabilities of CT complement the mapping of normal and abnormal tissue function performed by PET. Because of this, PET images are routinely read alongside CT images in order to both distinguish and localize metabolic irregularities. In the first instance, this has been achieved via the coregistration of separately acquired PET and CT images using fusion software, a technique which has especially proved to be effective for brain imaging. However, coregistration of images of other anatomical regions poses significant challenges . Difficu18F-FDG. This combined modality overcomes some of the drawbacks that are characteristic of standalone PET scanning, namely, the significant presence of noise in attenuation correction factors, the lengthy duration of scans, and the absence of anatomic markers [18F-FDG-PET/CT can lead to improved diagnostic accuracy [The use of integrated PET/CT in oncologic imaging has since become a widespread field of research, particularly with the utilization of  markers . While t markers . Studies markers . Some ce markers , 7, 11. accuracy . Finallyaccuracy . The ongaccuracy . in silico models of these radiobiological processes is particularly beneficial [ in silico modelling of tumours. In particular, it examines the various parameters that can be determined via PET and PET/CT imaging along with the assortment of radiotracers available for these purposes. The biophysical quantities used to quantify PET and PET/CT data, including SUV and compartmental models, are assessed. Finally, an overview of the existing in silico models that utilize PET or PET/CT data is provided.The significant interpatient variability in both tumour behaviour and normal tissue response to cancer therapy has prompted increasing demand for individualized treatment planning. Simulations of radiobiological processes in malignancies provide scope for the further optimization of individual treatment plans and to ultimately improve patient outcomes. The development of computer orneficial . It is hneficial –17. The  in silico modelling of tumour growth and treatment response. Similarly, since it is well established that tumour's oxygenation level contributes significantly to its radioresistance, modelling parameters that characterize tumour hypoxia and angiogenesis are also common. Increasingly, in silico models have expanded to incorporate additional contributing factors to tumour radiosensitivity, including intracellular tumour pH, gene expression, and cell-cycle simulation. The complexity of any given model dictates the number of characteristics simulated, as well as the accuracy with which each tumour characteristic is simulated. Simpler models may use averaged, macroscopic measures of a given tumour characteristic, while more complex models may simulate a tumour and its behaviour at the microscopic, molecular, and even atomic levels. Indeed, some of the most accurate, contemporary models are “multiscale”; they simulate tumour behaviour across multiple biological scales, reconciling the macroscopic and microscopic levels [With the objective of optimal, individualized treatment planning, many biological characteristics of a given tumour can be considered for computer simulation. In the case of radiation therapy, the proliferative potential of a tumour and its radiosensitivity are of particular interest. Parameters which describe tumour cell proliferation and repopulation characteristics are useful forc levels . DetailsThere are many approaches to modelling cell proliferation but it is useful to separately consider modelling at the macroscopic and microscopic scales. At the macroscopic scale, tumours are commonly simulated using continuum models. Using this approach, gross tumour morphology and behaviour are modelled under various environmental conditions and typically governed by a set of differential equations whose initial conditions serve as input parameters . Input pIn contrast to continuum tumour models, discrete tumour models developed at the microscopic scale simulate individual cell behaviour. Their input parameters correspondingly describe a set of biophysical rules applied to the modelled cells and the diversity of these rules varies across different models. Each cell is assigned an initial state and its status is subsequently tracked throughout the simulation. Consequently, discrete models directly simulate cell proliferation; a process which is mediated by input parameters such as proliferative potential, cell-cycle positions, and durations for different cell types, probability of cell division, cell loss rates, and maximum tumour radius or cell number . PatientThe adverse effects of tumour hypoxia on patient outcomes following radiotherapy have been well established. Indeed, hypoxia is often attributed to poor tumour control probabilities in locally advanced head and neck cancers, for which low oxygenation levels are common . AccordiOxygen information is generally modelled using an analytic approach. That is, sets of differential equations are used to describe oxygen diffusion and/or consumption rates both during tumour growth and in response to treatment. Even stochastic (discrete) tumour cell proliferation models that incorporate oxygen information typically employ a composite approach; oxygen and other substrate concentrations are generally governed by continuous fields. Since the oxygen distribution within a tumour is directly related to the extent and nature of its vasculature, many tumour hypoxia models incorporate blood vessel information into their simulations. The most sophisticated models simulate angiogenesis see  and its 2 values. Thus, for the successful simulation of tumour hypoxia, realistic initial pO2 conditions must be set. In order to categorize the oxygen status of tissue, binary approaches to oxygen modelling establish a defined threshold pO2 value below which the region is considered to be hypoxic. More robust models establish a more detailed relationship between tumour growth or treatment response and oxygen information and may incorporate both oxygen diffusion and oxygen consumption by tissue [2 distributions for use in patient-specific tumour models [Simulated oxygen distributions are typically quantified using partial oxygen tension or pOy tissue , 25. Addr models , 23, 26.The extent and nature of tumour vasculature significantly influence tumour growth and oxygen status. Consequently, the simulation of angiogenesis serves as a useful complement to models of tumour cell proliferation and hypoxia. Likecell proliferation, models of tumour-induced angiogenesis may be either continuous or discrete in nature. More advanced models utilize both approaches for simulating the various mechanisms involved in angiogenesis, such as capillary sprout formation, endothelial cell migration, blood flow, and vessel adaptation .αvβ3 integrins and tumour expression of VEGF, has been demonstrated by multiple groups [Input parameters related to vessel branching generally include probabilities of random endothelial cell migration, chemotaxis with tumour angiogenesis factor concentration , and haptotaxis with fibronectin gradients . The utie groups , 29. To e groups , 23. Spee groups .Though the intracellular pH of solid tumours is maintained in a range similar to that of normal cells, the extracellular pH of solid tumours is commonly acidic. The increased glucose metabolism of solid tumours, assisted by characteristically poor perfusion, is the most probable cause of their low extracellular pH. This is because glucose catabolism results in net acid production and insufficient vasculature cannot remove excess acid from the extracellular environment . in silico tumour growth modelling and the role played by acid gradients in triggering tumour invasion has been evaluated this way [+ ion concentration may be simulated in a continuum model utilizing reaction-diffusion partial differential equations, where input parameters such as acid production rate, reabsorption rate, and H+ ion diffusion coefficients may be obtained from measurement [Perhaps the most compelling value of including pH in tumour growth models arises from the acid-mediated tumour invasion hypothesis. This suggests that tumour cells develop phenotypic adaptations to the harmful effects of acidosis during carcinogenesis, traits that are not present in normal cells. Consequently, tumour cells are rendered relatively impervious to the decreased pH in the tumour microenvironment resulting from increased anaerobic glycolysis, which is otherwise toxic to normal tissue. Effectively the tumour provides for itself a selective growth advantage and a useful mechanism for invasion . Investithis way . Excess surement . in silico models incorporating tumour pH have not utilized noninvasive PET data for input. Though PET has been used for the measurement of pH since the 1970s and was the first noninvasive in vivo pH meter, it has historically been both an inaccurate and imprecise measurement tool [ in silico models of tumour growth [As with angiogenesis,ent tool . Howeverr growth . in silico tumour models has so far been limited to radiotracers specific to glucose metabolism, cell proliferation, and hypoxia. There is significant potential for the use of alternative radiotracers to obtain additional functional information for in silico models using PET. A list of radiotracers whose information has been directly incorporated into in silico models as well as those that show significant promise for such applications is provided in PET and PET/CT are able to image an increasing variety of physiological phenomena. This versatility arises from the ability to select a radiotracer that specifically targets a particular mechanism. Additionally, the diversity of PET tracers continues to expand with ongoing innovations in radiopharmaceutical production. Today, radiotracers exist for the imaging of metabolism, proliferation, perfusion, drug/receptor interactions, and gene expression. Despite this variety, the extent of PET data incorporated into18F-2-Fluoro-2-deoxy-glucose or FDG is by far the most commonly used and extensively researched PET radiotracer. Today, FDG-PET plays an important role in oncology. It has been recommended for use as an imaging tool additional to traditional radiological modalities in the appropriate clinical setting. In particular, it has demonstrated efficacy in the diagnosis, staging, unknown primary discovery, and the detection of cancer recurrence [Increased glucose consumption is a typical characteristic of most cancers. In hypoxic regions, the Pasteur effect results in the upregulation of anaerobic glycolysis and the GLUT 1 glucose transporter in tumour cells. However, even if oxygen is plentiful, cancers undergo accelerated glycolysis. This observation, called the Warburg effect, is widely attributed to mutations in oncogenes and tumour suppressor genes . Since FThe primary drawback of FDG-PET for oncologic imaging is that FDG uptake is not specific to cancer. That is, FDG-PET exhibits a poor level of specificity for certain applications. FDG uptake may be intense in benign diseases as well as in areas of infectious disease and inflammatory tissue. That is, there are many potential causes of false-positive PET signals in oncologic imaging , 35, 36. in silico models of both tumour growth and treatment response [Commensurate with the predominance of FDG as the PET radiotracer of choice, metabolic information provided by FDG-PET is often utilized inresponse , 20. Theresponse . Alterna18F-3-fluoro-3-deoxy-thymidine (FLT) is perhaps the most researched and the most utilized. FLT-PET is typically a less sensitive imaging modality than FDG-PET: the difference in FLT uptake between normal and malignant tissues is usually less pronounced than that for FDG [PET radiotracers specific to cell proliferation are an effective alternative to those specific to glucose metabolism, such as FDG. Of these tracers,  for FDG . However for FDG –41 as we for FDG . The upt for FDG , 44. Con in silico models of tumour growth and treatment response [The magnitude of FLT that is trapped in a tumour cell is proportional to the amount of DNA/RNA synthesis undertaken by the cell. Since the growth of malignant tissue is intricately related to DNA replication, the degree of FLT uptake is strongly correlated with proliferation rate. Accordingly, FLT-PET data is particularly useful for patient-specific tumour modelling, where proliferative rates are often of paramount interest. A group led by Benjamin Titz at the University of Wisconsin has correspondingly acquired cell proliferation information from FLT-PET data forresponse , 16.18F-fluoromisonidazole (FMISO) is the most extensively studied and clinically validated. FMISO uptake is inversely proportional to O2 level and perfusion does not restrict its delivery to malignant tissue. Several studies have demonstrated FMISO-PET to be a viable prognostic indicator of tumour response to treatment [In an effort to develop accurate, noninvasive measurement techniques of tumour hypoxia, a number of PET radiotracers have been produced which irreversibly bind to cells in poorly oxygenated conditions. Of these, reatment .FMISO-PET has not been universally adopted into routine clinical application because of a number of limitations inherent in the radiotracer. Since it relies on passive transport mechanisms, its uptake is relatively slow in hypoxic tumours, usually requiring 2–4 hours to be selectively retained in the target following injection . FMISO-P4-methylthiosemicarbazone) or Cu-ATSM [Alternative hypoxia-specific PET radiotracers have been developed in order to overcome the various limitations of FMISO. Several other nitroimidazole compounds have been developed for this purpose . In 1997 Cu-ATSM . Cu-ATSM Cu-ATSM . It is a Cu-ATSM . in silico tumour models [The effectiveness of Cu-ATSM for providing clinically relevant tumour oxygenation information has been confirmed in multiple studies and its predictive value of tumour behaviour and treatment response has been demonstrated –51. Perhr models , 16, 23.r models , followir models . Using p in silico models are yet to incorporate PET or PET/CT information beyond glucose metabolism, cell proliferation, and tumour oxygenation, there is scope for the use of tracers that image additional processes. Tumour acidosis arising from amplified glycolysis is a common feature of cancers and is a likely trigger of invasion into surrounding tissue [Althoughg tissue . Consequg tissue , 54. Theg tissue . pHLIP bg tissue . in silico tumour modelling. Though parameters related to angiogenesis can be indirectly obtained using hypoxia-specific PET-imaging, alternative markers of angiogenesis can instead be targeted. For example, vascular integrins are targeted by PET radiotracers containing the tripeptide sequence arginine-glycine-aspartic acid (RGD) [αvβ3 integrin is a receptor related to cell adhesion and involved in tumour-induced angiogenesis that can be imaged using radiotracers such as 18F-Galacto-RGD [As discussed in id (RGD) . In partacto-RGD .18F-dihydroxyphenylalanine (FDOPA) [18F labelled oestrogens such as 18F-fluoroestradiol (FES) [In models that simulate specific tumour types, PET information from alternative tracers might be useful. For example, neuroendocrine tumours are typically characterised by an increased L-DOPA decarboxylase activity . The ima (FDOPA)  and may ol (FES) . in silico models of tumour growth and treatment response greatly relies on the accurate and precise quantification of imaging data. This is especially relevant for PET and PET/CT, for which radiotracer uptake is dependent on a host of factors. SUV is the most extensively used parameter clinically for the analysis of PET tracers, but its high degree of sensitivity to multiple variables can render the comparison of SUVs taken at different times or between different centres to be extremely difficult [The integration of reliable imaging-based information intoifficult . in silico models of tumour growth and treatment response is also discussed.Details of the biophysical parameters used to quantify PET and PET/CT data are provided below. Their applications and limitations are discussed and compared, as well as the various methods that have been developed to overcome the potential pitfalls of a given measure. The present use of PET and PET/CT quantification measures inN is a factor normalizing for body weight, body surface area, or lean body mass. The overall denominator has units kBq/g. The radiotracer is commonly computed by scanning the patient for a 5–15-minute interval after a predetermined period  after radiotracer injection.The standardized uptake value is the quintessential parameter employed to analyse and quantify PET radiotracer data. It is defined as follows: max, mean, peak, or total SUV [In general, SUV depends on the time between injection and scanning as well as multiple image acquisition settings such as the reconstruction algorithm and scatter and attenuation corrections . Its comotal SUV . SUV mayotal SUV .2 values for use in in silico tumour models [Despite its limitations, SUV poses advantages over alternative quantification techniques such as compartmental methods see . It is tr models , 20, 23.Compartmental or kinetic modelling (CM) is the “gold standard” of quantification methods for PET data . In CM, Despite its accuracy and relative independence of confounding effects as compared to SUV, CM has the disadvantage of requiring a complex, time-intensive acquisition protocol. Techniques with which the requisite scan protocol complexity of CM can be overcome CMare an ongoing field of research , 63. In However, in the case of FMISO-PET imaging of hypoxia, the use of CM is warranted. Whilst FMISO can be used to identify and image tumour hypoxia, it typically exhibits poor tumour-to-background ratios using the standard SUV measure, generating highly variable results , 27. ComThe process of positron emission tomography is based on the coincident detection of colinear, 511 keV photons originating from an annihilation event. This measurement may be affected by an interaction between one or both of the photons and the attenuator prior to reaching the detectors. A colinear coincident event is consequently not detected and may instead register as scatter coincidence or no coincidence. To account for this signal loss, attenuation corrections are performed during PET image reconstruction in an effort to salvage the true radiotracer distribution. Until the development of PET/CT attenuation correction in PET was performed using a transmission scan taken immediately prior to the imaging scan, effectively doubling the total scan time. In modern PET/CT scanners, CT-based attenuation correction of PET images can be performed using the immediately available CT images. 511 keV linear attenuation values are obtained from the Hounsfield unit (HU) data provided by the CT using an appropriate transformation scheme , usuallyμ into HU for display. Since attenuation is directly proportional to attenuator density, the HU of a particular voxel may be interpreted as the density of the object within that voxel relative to that of water. Typical scans consist of image noise within the range of 10–50 HU, corresponding to a relative error of 1–5% [CT scanners convert attenuation coefficient distributions  of 1–5% . Consequ of 1–5% –68.Positive contrast agents within PET/CT may cause overestimation of PET attenuation with contrast-enhanced CT based attenuation corrections. This can lead to artifacts of apparently increased tracer uptake in regions of high contrast concentration within the PET image. However, such artifacts can often be attributed to an underlying vessel and hence do not cause problems with image interpretation . FurtherWith the advances in technology, the current imaging modalities offer a great variety of biological, biophysical, and clinical parameters to be further studied and implemented into complex tumour models. Computational modelling is an ever-increasing area of research in tumour biology and therapy. Depending on their design  models offer various levels of understanding of biological, biochemical, and biophysical processes occurring in tumours before and during treatment. Models are versatile in terms of input parameters, equations used, phenomena simulated, and end points. While never perfectly illustrating the biological reality, models are valuable complements to kinetic analysis of tumour growth and development, treatment outcome prediction, patient selection, and important decision-making towards personalized medicine.There are a large number of computational and mathematical tumour models that incorporate functional imaging data in the scientific literature. This is particularly true for PET and PET/CT. A detailed list is provided in Tumour growth models are an important initial step when modelling treatment response. Using dual-phase CT and FDG-PET imaging modalities, Liu et al. have developed a tumour growth model for pancreatic cancers , 71. The2), Thorwarth et al. came to a practical conclusion, whereby compartmental kinetic models are more reliable for hypoxia assessment than early static SUV measurements, due to the low uptake of FMISO by severely hypoxic cells.Perhaps the vast majority of the models address the challenge of tumour hypoxia and neovascularization , 23, 27.2) suggests that patient-based simulation can contribute towards individualized patient planning and treatment.Experimental probability density functions were employed by other groups to simulate the direction and spatial arrangement of microvascular tumour density, using patient-specific PET imaging information . The disHybrid models  are often used for complex assessment of tumour growth and behaviour under therapy, due to their versatility and ability to integrate mathematical/computational modelling with experimental data on different physical scales. The hybrid model developed by Titz and Jeraj is an example of this . DependiTo further prove the usefulness of complex multiscale models, the same group has simulated the effect of bevacizumab, an anti-VEGF agent, which is administered for targeting endothelial cell population in tumours . Tumour  in silico model development and refinement permits the simulation of cancer with ever-increasing accuracy, with the goal of optimally individualizing cancer management and improving overall patient outcome.The incorporation of patient-specific data into multiscale models is necessary for individualized, predictive simulation. This is an essential component of predictive oncology. Image-based information can be transformed into input parameters and incorporated into either probabilistic or deterministic equations governing their relationships and interdependences. Using these tools, countless hypotheses can then be generated and scenarios of “what if” can be simulated and solved. Models usually have the benefit of independence from the manner in which input parameters are obtained. This allows for the constant refinement of parameters with future innovations in measurement techniques, particularly in PET and PET/CT. Additionally, most models can be readily adapted to include new parameters in order to better resemble the real tumour environment. The widespread, continuing research into