Optimization of Y-90 Radioembolization Imaging for Post-Treatment Dosimetry on a Long Axial Field-of-View PET/CT Scanner.

BACKGROUND: PET imaging after yttrium-90 (Y-90) radioembolization is challenging because of the low positron fraction of Y-90 (32 × 10-6). The resulting low number of events can be compensated by the high sensitivity of long axial field-of-view (LAFOV) PET/CT scanners. Nevertheless, the reduced event statistics require optimization of the imaging protocol to achieve high image quality (IQ) and quantification accuracy sufficient for post-treatment dosimetry. METHODS: Two phantoms (NEMA IEC and AbdoMan phantoms, mimicking human liver) filled with Y-90 and a 4:1 sphere (tumor)-to-background ratio were scanned for 24 h with the Biograph Vision Quadra (Siemens Healthineers). Eight patients were scanned after Y-90 radioembolization (1.3-4.7 GBq) using the optimized protocol (obtained by phantom studies). The IQ, contrast recovery coefficients (CRCs) and noise were evaluated for their limited and full acceptance angles, different rebinned scan durations, numbers of iterations and post-reconstruction filters. The s-value-based absorbed doses were calculated to assess their suitability for dosimetry. RESULTS: The phantom studies demonstrate that two iterations, five subsets and a 4 mm Gaussian filter provide a reasonable compromise between a high CRC and low noise. For a 20 min scan duration, an adequate CRC of 56% (vs. 24 h: 62%, 20 mm sphere) was obtained, and the noise was reduced by a factor of 1.4, from 40% to 29%, using the full acceptance angle. The patient scan results were consistent with those from the phantom studies, and the impacts on the absorbed doses were negligible for all of the studied parameter sets, as the maximum percentage difference was -3.89%. CONCLUSIONS: With 2i5s, a 4 mm filter and a scan duration of 20 min, IQ and quantification accuracy that are suitable for post-treatment dosimetry of Y-90 radioembolization can be achieved.

Image Quality and Quantitative PET Parameters of Low-Dose [18F]FDG PET in a Long Axial Field-of-View PET/CT Scanner.

PET/CT scanners with a long axial field-of-view (LAFOV) provide increased sensitivity, enabling the adjustment of imaging parameters by reducing the injected activity or shortening the acquisition time. This study aimed to evaluate the limitations of reduced [18F]FDG activity doses on image quality, lesion detectability, and the quantification of lesion uptake in the Biograph Vision Quadra, as well as to assess the benefits of the recently introduced ultra-high sensitivity mode in a clinical setting. A number of 26 patients who underwent [18F]FDG-PET/CT (3.0 MBq/kg, 5 min scan time) were included in this analysis. The PET raw data was rebinned for shorter frame durations to simulate 5 min scans with lower activities in the high sensitivity (HS) and ultra-high sensitivity (UHS) modes. Image quality, noise, and lesion detectability (n = 82) were assessed using a 5-point Likert scale. The coefficient of variation (CoV), signal-to-noise ratio (SNR), tumor-to-background ratio (TBR), and standardized uptake values (SUV) including SUVmean, SUVmax, and SUVpeak were evaluated. Subjective image ratings were generally superior in UHS compared to the HS mode. At 0.5 MBq/kg, lesion detectability decreased to 95% (HS) and to 98% (UHS). SNR was comparable at 1.0 MBq/kg in HS (5.7 ± 0.6) and 0.5 MBq/kg in UHS (5.5 ± 0.5). With lower doses, there were negligible reductions in SUVmean and SUVpeak, whereas SUVmax increased steadily. Reducing the [18F]FDG activity to 1.0 MBq/kg (HS/UHS) in a LAFOV PET/CT provides diagnostic image quality without statistically significant changes in the uptake parameters. The UHS mode improves image quality, noise, and lesion detectability compared to the HS mode.

On the Use of Artificial Intelligence for Dosimetry of Radiopharmaceutical Therapies.

Routine clinical dosimetry along with radiopharmaceutical therapies is key for future treatment personalization. However, dosimetry is considered complex and time-consuming with various challenges amongst the required steps within the dosimetry workflow. The general workflow for image-based dosimetry consists of quantitative imaging, the segmentation of organs and tumors, fitting of the time-activity-curves, and the conversion to absorbed dose. This work reviews the potential and advantages of the use of artificial intelligence to improve speed and accuracy of every single step of the dosimetry workflow.

Long-acting lenacapavir protects macaques against intravenous challenge with simian-tropic HIV.

BACKGROUND: Long-acting subcutaneous lenacapavir (LEN), a first-in-class HIV capsid inhibitor approved by the US FDA for the treatment of multidrug-resistant HIV-1 with twice yearly dosing, is under investigation for HIV-1 pre-exposure prophylaxis (PrEP). We previously derived a simian-tropic HIV-1 clone (stHIV-A19) that encodes an HIV-1 capsid and replicates to high titres in pigtail macaques (PTM), resulting in a nonhuman primate model well-suited for evaluating LEN PrEP in vivo. METHODS: Lenacapavir potency against stHIV-A19 in PTM peripheral blood mononuclear cells in vitro was determined and subcutaneous LEN pharmacokinetics were evaluated in naïve PTMs in vivo. To evaluate the protective efficacy of LEN PrEP, naïve PTMs received either a single subcutaneous injection of LEN (25 mg/kg, N = 3) or vehicle (N = 4) 30 days before a high-dose intravenous challenge with stHIV-A19, or 7 daily subcutaneous injections of a 3-drug control PrEP regimen starting 3 days before stHIV-A19 challenge (N = 3). FINDINGS: In vitro, LEN showed potent antiviral activity against stHIV-A19, comparable to its potency against HIV-1. In vivo, subcutaneous LEN displayed sustained plasma drug exposures in PTMs. Following stHIV-A19 challenge, while all vehicle control animals became productively infected, all LEN and 3-drug control PrEP animals were protected from infection. INTERPRETATION: These findings highlight the utility of the stHIV-A19/PTM model and support the clinical development of long-acting LEN for PrEP in humans. FUNDING: Gilead Sciences as part of a Cooperative Research and Development Agreement between Gilead Sciences and Frederick National Lab; federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. 75N91019D00024/HHSN261201500003I; NIH grant R01AI078788.

Gene Editing of Primary Rhesus Macaque B Cells.

B cells and their progeny are the sources of highly expressed antibodies. Their high protein expression capabilities together with their abundance, easy accessibility via peripheral blood, and amenability to simple adoptive transfers have made them an attractive target for gene editing approaches to express recombinant antibodies or other therapeutic proteins. The gene editing of mouse and human primary B cells is efficient, and mouse models for in vivo studies have shown promise, but feasibility and scalability for larger animal models have so far not been demonstrated. We, therefore, developed a protocol to edit rhesus macaque primary B cells in vitro to enable such studies. We report conditions for in vitro culture and gene-editing of primary rhesus macaque B cells from peripheral blood mononuclear cells or splenocytes using CRISPR/Cas9. To achieve the targeted integration of large (<4.5 kb) cassettes, a fast and efficient protocol was included for preparing recombinant adeno-associated virus serotype 6 as a homology-directed repair template using a tetracycline-enabled self-silencing adenoviral helper vector. These protocols enable the study of prospective B cell therapeutics in rhesus macaques.

Evolution of antibody immunity to SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected 78 million individuals and is responsible for over 1.7 million deaths to date. Infection is associated with the development of variable levels of antibodies with neutralizing activity, which can protect against infection in animal models1,2. Antibody levels decrease with time, but, to our knowledge, the nature and quality of the memory B cells that would be required to produce antibodies upon reinfection has not been examined. Here we report on the humoral memory response in a cohort of 87 individuals assessed at 1.3 and 6.2 months after infection with SARS-CoV-2. We find that titres of IgM and IgG antibodies against the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 decrease significantly over this time period, with IgA being less affected. Concurrently, neutralizing activity in plasma decreases by fivefold in pseudotype virus assays. By contrast, the number of RBD-specific memory B cells remains unchanged at 6.2 months after infection. Memory B cells display clonal turnover after 6.2 months, and the antibodies that they express have greater somatic hypermutation, resistance to RBD mutations and increased potency, indicative of continued evolution of the humoral response. Immunofluorescence and PCR analyses of intestinal biopsies obtained from asymptomatic individuals at 4 months after the onset of coronavirus disease 2019 (COVID-19) revealed the persistence of SARS-CoV-2 nucleic acids and immunoreactivity in the small bowel of 7 out of 14 individuals. We conclude that the memory B cell response to SARS-CoV-2 evolves between 1.3 and 6.2 months after infection in a manner that is consistent with antigen persistence.

Mycosis fungoides-type cutaneous T-cell lymphoma (MF-CTCL) epidemiology and treatment pathway in Spain: new insights for an accurate description.

BACKGROUND: Mycosis fungoides-type cutaneous T-cell lymphoma (MF-CTCL) is a rare lymphoma localized in the skin. Due to its indolent nature and similarity to other skin conditions, diagnosis is often delayed or incorrect. Consequently, accurate calculations of incidence and prevalence are difficult to make. The treatment pathway taken by MF-CTCL patients can differ depending upon local healthcare systems, clinical policies and guidelines. AIMS: This study aims to (1) provide an estimate for the prevalence of treated MF-CTCL patients in Spain, (2) describe the Spanish patient treatment pathways for MF-CTCL, including quantification of the distribution of patients between primary, secondary and tertiary care institutions, and (3) investigate and quantify the treatment preferences of physicians. METHODOLOGY: This study employed primary market research methodologies to facilitate the collection of patient numbers and treatment practices from healthcare professionals (HCPs) and patients. LIMITATIONS: Poor diagnosis of MF-CTCL may mean that actual prevalence levels in the broader population are higher than those estimated by this analysis of treated patients. This study was reliant upon accurate reporting by HCPs of patient numbers and their personal treatment practices. The rarity of the condition means the patient sample size is relatively small and limits possible accuracy of the quantitative analyses of patient-derived data, although this is supplemented by HCP-derived data in the analysis. FINDINGS: Around 75% of MF-CTCL patients in Spain report that the initial diagnosis by their general practitioner is incorrect. This is usually due to underestimation of severity or type of skin disease. Once they have been correctly diagnosed (usually by a dermatologist) in secondary care, the management of MF-CTCL is led by dermatologists. In 39% of patients, shared care teams are also involved in patient management. Following diagnosis, the majority of patient management is conducted by secondary or tertiary care centers. CONCLUSIONS: Incidence rates have increased in recent years, and possible reasons for this include improving levels of diagnosis. Survival in MF-CTCL has also increased over the last few decades. This trend appears to be reflected in the prevalence reported in this study, which is higher than suggested by some other estimates. However, it is still likely that there are further undiagnosed MF-CTCL patients in Spain due to the challenges of diagnosis at the primary care level.

Electron-Induced Formation of Ethyl Methyl Ether in Condensed Mixtures of Methanol and Ethylene.

Electron-induced reactions in condensed mixtures of ethylene (C2H4) and methanol (CH3OH) lead to the formation of ethyl methyl ether (EME, C2H5OCH3), as shown by post-irradiation thermal desorption spectrometry (TDS). In contrast to the electron-induced reaction between water (H2O) and C2H4, product formation as a consequence of proton transfer following electron attachment (EA) to C2H4 is not observed in the analogous reaction between CH3OH and C2H4. However, a resonant process centered around 5.5 eV and a threshold-type increase of product yield starting at 9 eV is observed. On the basis of the presence and absence of particular side products after irradiation of the mixture as well as of the pure parent compounds, reaction mechanisms related to the two energy regimes are proposed. Below the ionization threshold of the reactants, dissociative electron attachment (DEA) to CH3OH triggers the reaction sequence by producing reactive methoxy radicals, which attack neighboring C2H4 molecules. The resulting adduct then abstracts a hydrogen atom to yield EME. Above but near the ionization threshold, electron impact ionization (EI) produces primarily intact molecular cations, which drive the reaction by converting the repulsive Coulomb force between the high electron densities at the reactive sites of the two neutral parent species into an attractive force. This again induces the formation of an adduct between the two reactants that rearranges to the product EME. Fragmentation of the molecular CH3OH+• cation into CH3O+, however, may provide an additional reaction pathway toward EME. In this scenario, CH3O+ attacks a neighboring C2H4 molecule. The resulting adduct is then neutralized by a thermalized electron and abstracts a hydrogen atom from a nearby CH3OH molecule to yield EME.

hIAPP forms toxic oligomers in plasma.

In diabetes, hyperamylinemia contributes to cardiac dysfunction. The interplay between hIAPP, blood glucose and other plasma components is, however, not understood. We show that glucose and LDL interact with hIAPP, resulting in ß-sheet rich oligomers with increased ß-cell toxicity and hemolytic activity, providing mechanistic insights for a direct link between diabetes and cardiovascular diseases.

Endoscopic Vacuum Therapy (EVT)-a New Concept for Complication Management in Bariatric Surgery.

BACKGROUND: Bariatric surgery is the most efficient therapy for morbid obesity. Staple line and anastomotic leakage are the most feared postoperative complications after Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy (LSG). Traditional treatment options like revisional surgery and endoscopic stent placement are associated with high morbidity and mortality as well as variable success rates. Endoscopic vacuum therapy (EVT) has shown to be a new successful and feasible treatment option for leaks of different etiology after major gastro-esophageal surgery. METHOD: We report a case of the EVT principle being applied in a patient with three major leaks located apart from each other within the gastric staple line after LSG for morbid obesity (BMI 62.7). EVT was initiated on postoperative day 8. RESULTS: In total, 18 endoscopic interventions were performed in 72 days, the vacuum sponge being replaced endoscopically every 4 days. Hospital length of stay was 106 days. No relevant procedure related complications were observed during the course of therapy and during the follow up. CONCLUSION: EVT of postoperative leaks in the upper GI tract has been shown to be feasible and safe. It combines defect closure and effective drainage and allows a periodic inspection of the wound cavity. In case of therapeutic failure, it does not jeopardize surgical repair or stent placement. Even though the techniques and materials used in EVT still vary considerably according to local expertise, EVT has the potential to succeed as a nonsurgical, feasible, safe, and effective treatment option for postoperative leaks in bariatric surgery.

Simian Immunodeficiency Virus Infection of Chimpanzees (Pan troglodytes) Shares Features of Both Pathogenic and Non-pathogenic Lentiviral Infections.

The virus-host relationship in simian immunodeficiency virus (SIV) infected chimpanzees is thought to be different from that found in other SIV infected African primates. However, studies of captive SIVcpz infected chimpanzees are limited. Previously, the natural SIVcpz infection of one chimpanzee, and the experimental infection of six chimpanzees was reported, with limited follow-up. Here, we present a long-term study of these seven animals, with a retrospective re-examination of the early stages of infection. The only clinical signs consistent with AIDS or AIDS associated disease was thrombocytopenia in two cases, associated with the development of anti-platelet antibodies. However, compared to uninfected and HIV-1 infected animals, SIVcpz infected animals had significantly lower levels of peripheral blood CD4+ T-cells. Despite this, levels of T-cell activation in chronic infection were not significantly elevated. In addition, while plasma levels of ß2 microglobulin, neopterin and soluble TNF-related apoptosis inducing ligand (sTRAIL) were elevated in acute infection, these markers returned to near-normal levels in chronic infection, reminiscent of immune activation patterns in 'natural host' species. Furthermore, plasma soluble CD14 was not elevated in chronic infection. However, examination of the secondary lymphoid environment revealed persistent changes to the lymphoid structure, including follicular hyperplasia in SIVcpz infected animals. In addition, both SIV and HIV-1 infected chimpanzees showed increased levels of deposition of collagen and increased levels of Mx1 expression in the T-cell zones of the lymph node. The outcome of SIVcpz infection of captive chimpanzees therefore shares features of both non-pathogenic and pathogenic lentivirus infections.

Frameshift-derived neoantigens constitute immunotherapeutic targets for patients with microsatellite-instable haematological malignancies: frameshift peptides for treating MSI+ blood cancers.

PURPOSE: Microsatellite instability (MSI) resulting from loss of functional DNA mismatch repair was recently found in various haematological disorders. In coding sequences, MSI leads to frameshift mutations (FSMs) and the production of C-terminally altered proteins which are foreign to the immune system. Here, we wondered whether these frame-shifted peptide (FSP) sequences represent tumour-specific antigens also for MSI(+) leukaemia and lymphomas (L/L). MATERIAL AND METHODS: A total of 33 coding region microsatellites were examined in MSI(+) L/L cell lines for the presence of FSMs. Thereafter, recognition of MSI(+) cells by established FSP-specific CD8(+) T cell lines was quantified using interferon (IFN)-γ enzyme-linked immunospot (ELISpot) assays. In each experiment, MSI(+) L/L cell lines and T2 targets exogenously loaded with the cognate peptide (=internal control) were employed. Supplementary, lytic activity towards tumour cells was analysed by standard chromium release assay ((51)Cr). RESULTS: Mutational profiling of 33 coding microsatellite loci in nine MSI(+) L/L cell lines revealed instability in at least nine microsatellites. In each cell line, a distinct mutational profile was observed. Only three of the 33 loci were stable. FSP-specific and human leukocyte antigen-A2 (HLA-A2)-restricted T cells specifically recognised MSI(+) L/L cells endogenously expressing TGFßRII(-1), Caspase 5 (-1) and MSH3 (-1) in ELISpot assays. Moreover, specific killing of Caspase 5 (-1) and MSH3 (-1) expressing L/L cell lines was achieved in functional cytotoxicity assays. CONCLUSION: Data presented here expand the importance of FSPs as shared and general tumour-specific antigens. Consequently, they open new avenues for specific immunotherapies not only for solid but also for MSI(+) haematological malignancies.

Herpesvirus saimiri infection of rhesus macaques: a model for acute rhadinovirus-induced t-cell transformation and oncogenesis.

Herpesvirus saimiri (HVS) causes acute lymphoma and leukemia upon experimental infection of various monkey species. HVS strain C488 is also capable of transforming human T-lymphocytes to stable growth in culture. The most susceptible species for oncogenesis are New World primates, in particular the cottontop tamarin (Saguinus oedipus). However, Old World monkeys such as macaques are the most used animal model for the close-to-human situation. The limited data on HVS infection in Old World monkeys prompted us to investigate susceptibility to infection and disease induction by HVS in macaques. After having established that rhesus macaques can be infected productively, and that rhesus T-cells can be transformed in vivo by HVS, we observed induction of lymphoma in all inoculated animals. Pre-existing humoral immunity in part of the rhesus colony capable of blocking HVS infection could be overcome by preselecting rhesus macaques for lack of this immunity of unknown origin. HVS infection of rhesus macaques as compared to that of New World monkeys has the advantages that disease progression is more prolonged, and larger blood volumes can be collected, which allows more extended analyses. Also, rhesus monkeys are the best immunologically and immunogenetically characterized primate species next to humans. This model could be useful for the evaluation of candidate tumor vaccines and to test novel approaches for cancer immunotherapy. In addition, HVS infection of macaques could eventually be useful as a surrogate model to address certain questions in rhadinovirus-induced human cancer such as effusion lymphoma or Kaposi's sarcoma.

Prognostic impact of underlying liver fibrosis and cirrhosis after curative resection of hepatocellular carcinoma.

BACKGROUND: In the case of hepatocellular carcinoma (HCC), underlying liver pathology may not only determine the feasibility of surgery but may also affect the postsurgical outcome. We report our experience after curative liver resection for HCC in patients with normal liver, liver fibrosis, and liver cirrhosis. METHODS: A total of 72 patients after liver resection with curative intention were analyzed. Histopathologic findings of tumor-unaffected liver tissue were used for retrospective classification: group A (normal liver); group B (liver fibrosis); group C (liver cirrhosis). The groups were compared for differences in short-term surgical results, total survival, and recurrence-free survival. RESULTS: The rate of major complications was 34.7% and did not significantly differ among groups. The overall perioperative mortality rate was 9.7%, with one patient dying in group A and three patients dying in each of the other two groups. Including perioperative mortality, the median overall survival for the whole group was 37.3 months (95% confidence interval 29.3-45.2 months). The respective 1-, 2-, and 5-year survival rates for group A (n = 21) were 86%, 71%, and 50% and for group C (n = 24) 62%, 50%, and 17%. The overall survival of group B (n = 27) was intermediate (log-rank, P = 0.032). The respective recurrence-free survival rates were 76%, 42%, and 20% for group A and 39%, 13%, and 4% for group C, with group B being intermediate (log-rank, P = 0.016). CONCLUSIONS: Our data demonstrate that liver resection in the presence of compensated liver cirrhosis is feasible but associated with a significantly impaired prognosis for overall and recurrence-free survival. The management of cirrhotic patients with compensated liver function and HCC therefore also requires the opportunity for transplantation.

Unusual clinical presentation of primary hypothyroidism in a very young infant caused by autoimmune thyroiditis: case report and update of the literature.

Acquired primary hypothyroidism in infancy can be related to autoimmune thyroiditis and can present with unusual symptoms, such as muscle pseudohypertrophy and pituitary tumor. This condition can cause permanent deficits in psychomotor development and growth despite adequate replacement with L: -thyroxine.

Mucosal cytology in the determination of the pubertal status in girls.

AIM: To assess and validate the diagnostic value of buccal and vaginal smears in the ambulatory care of girls with potential disorders of puberty. METHODS: Smears were obtained from 77 girls who presented for assessment of their pubertal status, stained as described by Papanicolaou, examined for signs of estrogenization according to the method of Schmitt, and compared with the clinical status. RESULTS: Vaginal but not buccal smears reflect accurately the changes of sexual maturation, even more sensitive than single serum hormone measurements. CONCLUSIONS: Vaginal smears represent a valid, reproducible, and well-tolerated diagnostic tool in the ambulatory care of peripubertal girls to identify their estrogen status with high sensitivity and specificity. The decision to perform confirmative but invasive diagnostic procedures can be based on auxology, physical examination, bone age determination, and analysis of vaginal smears.