The hindbrain and cortico-reticular pathway in adolescent idiopathic scoliosis

AIM

To characterise the corticoreticular pathway (CRP) in a case-control cohort of adolescent idiopathic scoliosis (AIS) patients using high-resolution slice-accelerated readout-segmented echo-planar diffusion tensor imaging (DTI) to enhance the discrimination of small brainstem nuclei in comparison to automated whole-brain volumetry and tractography and their clinical correlates.

MATERIALS AND METHODS

Thirty-four participants (16 AIS patients, 18 healthy controls) underwent clinical and orthopaedic assessments and brain magnetic resonance imaging (MRI) on a 3 T MRI machine. Automated whole-brain volume-based morphometry, tract-based spatial statistics analysis, and manual CRP tractography by two independent raters were performed. Intra-rater and inter-rater agreement of DTI metrics from CRP tractography were assessed by intraclass correlation coefficient. Normalised structural brain volumes and DTI metrics were compared between groups using Student's t-tests. Linear correlation analysis between imaging parameters and clinical scores was also performed.

RESULTS

AIS patients demonstrated a significantly larger pons volume compared to controls (p=0.006). Significant inter-side CRP differences in mean (p=0.02) and axial diffusivity (p=0.01) were found in patients only. Asymmetry in CRP fractional anisotropy significantly correlated with the Cobb angle (p=0.03).

CONCLUSION

Relative pontine hypertrophy and asymmetry in CRP DTI metrics suggest central supranuclear inter-hemispheric imbalance in AIS, and support the role of the CRP in axial muscle tone. Longitudinal evaluation of CRP DTI metrics in the prediction of AIS progression may be clinically relevant.

A randomized double-blinded trial to assess recurrence of systemic allergic reactions following COVID-19 mRNA vaccination

BACKGROUND

Systemic allergic reactions (sARs) following coronavirus disease 2019 (COVID-19) mRNA vaccines were initially reported at a higher rate than after traditional vaccines.

OBJECTIVE

We aimed to evaluate the safety of revaccination in these individuals and to interrogate mechanisms underlying these reactions.

METHODS

In this randomized, double-blinded, phase 2 trial, participants aged 16 to 69 years who previously reported a convincing sAR to their first dose of COVID-19 mRNA vaccine were randomly assigned to receive a second dose of BNT162b2 (Comirnaty) vaccine and placebo on consecutive days in a blinded, 1:1 crossover fashion at the National Institutes of Health. An open-label BNT162b2 booster was offered 5 months later if the second dose did not result in severe sAR. None of the participants received the mRNA-1273 (Spikevax) vaccine during the study. The primary end point was recurrence of sAR following second dose and booster vaccination; exploratory end points included biomarker measurements.

RESULTS

Of 111 screened participants, 18 were randomly assigned to receive study interventions. Eight received BNT162b2 second dose followed by placebo; 8 received placebo followed by BNT162b2 second dose; 2 withdrew before receiving any study intervention. All 16 participants received the booster dose. Following second dose and booster vaccination, sARs recurred in 2 participants (12.5%; 95% CI, 1.6 to 38.3). No sAR occurred after placebo. An anaphylaxis mimic, immunization stress-related response (ISRR), occurred more commonly than sARs following both vaccine and placebo and was associated with higher predose anxiety scores, paresthesias, and distinct vital sign and biomarker changes.

CONCLUSIONS

Our findings support revaccination of individuals who report sARs to COVID-19 mRNA vaccines. Distinct clinical and laboratory features may distinguish sARs from ISRRs.

Pearls and pitfalls in food protein-induced enterocolitis syndrome (FPIES)

Background: Food protein-induced enterocolitis syndrome (FPIES) is a rare, non-immunoglobulin E (IgE) mediated gastrointestinal food hypersensitivity. It is a clinical diagnosis commonly characterized by profuse vomiting 1 to 4 hours after ingestion of the triggering food(s). Objective: The objective was to increase awareness of FPIES and review the epidemiology, clinical presentation, pathogenesis, diagnosis, and management of FPIES. The lack of availability of a definite biomarker or diagnostic tool often leads to a delay in diagnosis. Methods: A literature search of salient articles that described case reports and case series of FPIES and their management were analyzed. Results: A case of FPIES with a literature review is presented with emphasis on clinical pearls and pitfalls. FPIES is a diagnosis of exclusion and the mainstay of treatment is avoidance of the trigger food(s) for at least 12-18 months from the last exposure. Conclusion: As FPIES is a non-IgE-mediated reaction, allergy testing via skin-prick test or blood tests to measure food IgE antibodies is not routinely recommended. Many children outgrow FPIES by 3-4 years of age. Supervised oral food challenge is recommended to assess acquisition of tolerance.

Aphelenchoides varicaudatus (Nematoda: Aphelenchoididae) and Helicotylenchus erythrinae (Nematoda: Hoplolaimidae) from Garlic Plantation in Magelang, Central Java, Indonesia

There were two most found genera of plant parasitic nematodes from garlic plantation in Magelang, Central Java, Indonesia which suffered losses due to bulb rot, Aphelenchoides and Helicotylenchus. Polymerase Chain Reaction (PCR) was conducted using a pair of universal nematode primer (D2A/D3B) to determine the Aphelenchoides and Helicotylenchus species from those host. Both genera were amplified at ~780 bp. The Blast-N results for the Aphelenchoides showed high identity to Aphelenchoides varicaudatus from Yunnan China (HQ283353) with 99.47 % identity, while the Helicotylenchus showed 95.22 % identity to Helicotylenchus erythrinae from Colombia (MT321739). From morphological and molecular data, we confirm that the Aphelenchoides species is A. varicaudatus. Based on female morphological character, Helicotylenchus species refers to H. erythrinae. Which is also supported by its nucleotide alignment which has same region character as H. erythrinae (MT321739). This is the first report of molecular characterization of H. erythrinae in Indonesia.

Exploration and analysis of R-loop mapping data with RLBase

R-loops are three-stranded nucleic acid structures formed from the hybridization of RNA and DNA. In 2012, Ginno et al. introduced the first R-loop mapping method. Since that time, dozens of R-loop mapping studies have been conducted, yielding hundreds of publicly available datasets. Current R-loop databases provide only limited access to these data. Moreover, no web tools for analyzing user-supplied R-loop datasets have yet been described. In our recent work, we reprocessed 810 R-loop mapping samples, building the largest R-loop data resource to date. We also defined R-loop consensus regions and developed a framework for R-loop data analysis. Now, we introduce RLBase, a user-friendly database that provides the capability to (i) explore hundreds of public R-loop mapping datasets, (ii) explore R-loop consensus regions, (iii) analyze user-supplied data and (iv) download standardized and reprocessed datasets. RLBase is directly accessible via the following URL: https://gccri.bishop-lab.uthscsa.edu/shiny/rlbase/.

Rdh54/Tid1 inhibits Rad51-Rad54-mediated D-loop formation and limits D-loop length

Displacement loops (D-loops) are critical intermediates formed during homologous recombination. Rdh54 (a.k.a. Tid1), a Rad54 paralog in Saccharomyces cerevisiae, is well-known for its role with Dmc1 recombinase during meiotic recombination. Yet contrary to Dmc1, Rdh54/Tid1 is also present in somatic cells where its function is less understood. While Rdh54/Tid1 enhances the Rad51 DNA strand invasion activity in vitro, it is unclear how it interplays with Rad54. Here, we show that Rdh54/Tid1 inhibits D-loop formation by Rad51 and Rad54 in an ATPase-independent manner. Using a novel D-loop Mapping Assay, we further demonstrate that Rdh54/Tid1 uniquely restricts the length of Rad51-Rad54-mediated D-loops. The alterations in D-loop properties appear to be important for cell survival and mating-type switch in haploid yeast. We propose that Rdh54/Tid1 and Rad54 compete for potential binding sites within the Rad51 filament, where Rdh54/Tid1 acts as a physical roadblock to Rad54 translocation, limiting D-loop formation and D-loop length.

SETX (senataxin), the helicase mutated in AOA2 and ALS4, functions in autophagy regulation

SETX (senataxin) is an RNA/DNA helicase that has been implicated in transcriptional regulation and the DNA damage response through resolution of R-loop structures. Mutations in SETX result in either of two distinct neurodegenerative disorders. SETX dominant mutations result in a juvenile form of amyotrophic lateral sclerosis (ALS) called ALS4, whereas recessive mutations are responsible for ataxia called ataxia with oculomotor apraxia type 2 (AOA2). How mutations in the same protein can lead to different phenotypes is still unclear. To elucidate AOA2 disease mechanisms, we first examined gene expression changes following SETX depletion. We observed the effects on both transcription and RNA processing, but surprisingly observed decreased R-loop accumulation in SETX-depleted cells. Importantly, we discovered a strong connection between SETX and the macroautophagy/autophagy pathway, reflecting a direct effect on transcription of autophagy genes. We show that SETX depletion inhibits the progression of autophagy, leading to an accumulation of ubiquitinated proteins, decreased ability to clear protein aggregates, as well as mitochondrial defects. Analysis of AOA2 patient fibroblasts also revealed a perturbation of the autophagy pathway. Our work has thus identified a novel function for SETX in the regulation of autophagy, whose modulation may have a therapeutic impact for AOA2.Abbreviations: 3'READS: 3' region extraction and deep sequencing; ACTB: actin beta; ALS4: amyotrophic lateral sclerosis type 4; AOA2: ataxia with oculomotor apraxia type 2; APA: alternative polyadenylation; AS: alternative splicing; ATG7: autophagy-related 7; ATP6V0D2: ATPase H+ transporting V0 subunit D2; BAF: bafilomycin A₁; BECN1: beclin 1; ChIP: chromatin IP; Chloro: chloroquine; CPT: camptothecin; DDR: DNA damage response; DNMT1: DNA methyltransferase 1; DRIP: DNA/RNA IP; DSBs: double strand breaks; EBs: embryoid bodies; FTD: frontotemporal dementia; GABARAP: GABA type A receptor-associated protein; GO: gene ontology; HR: homologous recombination; HTT: huntingtin; IF: immunofluorescence; IP: immunoprecipitation; iPSCs: induced pluripotent stem cells; KD: knockdown; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MN: motor neuron; MTORC1: mechanistic target of rapamycin kinase complex 1; PASS: PolyA Site Supporting; PFA: paraformaldehyde; RNAPII: RNA polymerase II; SCA: spinocerebellar ataxia; SETX: senataxin; SMA: spinal muscular atrophy; SMN1: survival of motor neuron 1, telomeric; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TSS: transcription start site; TTS: transcription termination site; ULK1: unc-51 like autophagy activating kinase 1; WB: western blot; WIPI2: WD repeat domain, phosphoinositide interacting 2; XRN2: 5'-3' exoribonuclease 2.

Periventricular white matter hyperintensity burden and cognitive impairment in early Parkinson's disease

BACKGROUND AND PURPOSE

This study quantified the total brain and periventricular white matter hyperintensity (WMH) burdens in patients with early Parkinson's disease (PD) and explored their associations with cardiovascular risk factors and cognitive performance.

METHODS

A total of 175 non-demented patients with early PD who had undergone baseline brain magnetic resonance imaging were included. Comprehensive neurocognitive testing was conducted to identify PD with mild cognitive impairment (PD-MCI) and to evaluate performances in individual cognitive domains. Cardiovascular risk was expressed as a modified Framingham 10-year cardiovascular risk score (mFRS).

RESULTS

A total of 53.7% of this early PD cohort fulfilled the diagnostic criteria for PD-MCI. An increase in mFRS was significantly associated with increases in the total brain WMH (P = 0.015) and periventricular WMH (P = 0.040) burden, independent of age and gender. The periventricular WMH burden was significantly associated with PD-MCI (P = 0.046) in early PD, independent of cardiovascular risk factors. Patients in the 5th quintile of periventricular WMH burden were 8.6 times more likely to have PD-MCI compared with patients in the 1st quintile of periventricular WMH burden (P = 0.004). However, total brain WMH burden was not associated with PD-MCI (P = 0.158). In individual cognitive domains, heavier periventricular WMH burden was associated with worse executive function and visuospatial function independent of cardiovascular risk factors.

CONCLUSION

Periventricular WMHs are a useful imaging biomarker for cognitive impairment in early PD. Cardiovascular risk factors, although associated with periventricular WMHs, were unable to fully explain the association between periventricular WMHs and cognitive impairment in early PD.

Understanding K trans: a simulation study based on a multiple-pathway model

The transfer constant K ^trans is commonly employed in dynamic contrast-enhanced MRI studies, but the utility and interpretation of K ^trans as a potential biomarker of tumor vasculature remains unclear. In this study, computer simulations based on a comprehensive tracer kinetic model with multiple pathways was used to provide clarification on the interpretation and application of K ^trans. Tissue concentration-time curves pertaining to a wide range of transport conditions were simulated using the multiple-pathway (MP) model and fitted using the generalized kinetic (GK) and extended GK models. Relationships between K ^trans and plasma flow F _p, vessel permeability PS and extraction rate EF _p under various transport conditions were assessed by correlation and regression analysis. Results show that the MP model provides an alternative two-tier interpretation of K ^trans based on the vascular transit time. K ^trans is primarily associated with F _p and EF _p respectively, in the slow and rapid vascular transit states, independent of the magnitude of PS. The relative magnitudes of PS and F _p only serve as secondary constraints for which K ^trans can be further associated with EF _p and PS in the slow and rapid transit states, respectively.

A longitudinal study of whole body, tissue, and cellular physiology in a mouse model of fibrosing NASH with high fidelity to the human condition

The sequence of events that lead to inflammation and fibrosing nonalcoholic steatohepatitis (NASH) is incompletely understood. Hence, we investigated the chronology of whole body, tissue, and cellular events that occur during the evolution of diet-induced NASH. Male C57Bl/6 mice were assigned to a fast-food (FF; high calorie, high cholesterol, high fructose) or standard-chow (SC) diet over a period of 36 wk. Liver histology, body composition, mitochondrial respiration, metabolic rate, gene expression, and hepatic lipid content were analyzed. Insulin resistance [homeostasis model assessment-insulin resistance (HOMA-IR)] increased 10-fold after 4 wk. Fibrosing NASH was fully established by 16 wk. Total hepatic lipids increased by 4 wk and remained two- to threefold increased throughout. Hepatic triglycerides declined from sixfold increase at 8 wk to threefold increase by 36 wk. In contrast, hepatic cholesterol levels steadily increased from baseline at 8 wk to twofold by 36 wk. The hepatic immune cell population altered over time with macrophages persisting beyond 16 wk. Mitochondrial oxygen flux rates of FF mice diet were uniformly lower with all the tested substrates (13-276 pmol·s^-1·ml^-1 per unit citrate synthase) than SC mice (17-394 pmol·s^-1·ml^-1 per unit citrate synthase) and was accompanied by decreased mitochondrial:nuclear gene copy number ratios after 4 wk. Metabolic rate was lower in FF mice. Mitochondrial glutathione was significantly decreased at 24 wk in FF mice. Expression of dismutases and catalase was also decreased in FF mice. The evolution of NASH in the FF diet-induced model is multiphasic, particularly in terms of hepatic lipid composition. Insulin resistance precedes hepatic inflammation and fibrosis. Mitochondrial dysfunction and depletion occur after the histological features of NASH are apparent. Collectively, these observations provide a unique overview of the sequence of changes that coevolve with the histological evolution of NASH.NEW & NOTEWORTHY This study demonstrates in a first of kind longitudinal analysis, the evolution of nonalcoholic steatohepatitis (NASH) on a fast-food diet-induced model. Key findings include 1) hepatic lipid composition changes in a multiphasic fashion as NASH evolves; 2) insulin resistance precedes hepatic inflammation and fibrosis, answering a longstanding chicken-and-egg question regarding the relationship of insulin resistance to liver histology in NASH; and 3) mitochondrial dysfunction and depletion occur after the histological features of NASH are apparent.

Intravoxel incoherent motion and diffusion tensor imaging of early renal fibrosis induced in a murine model of streptozotocin induced diabetes

INTRODUCTION

To assess if parameters in intravoxel incoherent motion (IVIM) and diffusion tensor imaging (DTI) can be used to evaluate early renal fibrosis in a mouse model of diabetic nephropathy.

MATERIALS & METHODS

In a population of 38 male CD1 mice (8weeks old, 20-30g), streptozotocin induced diabetes was created in 20 mice via a single intraperitoneal injection of streptozotocin at 150mg/kg, while 18 mice served as control group. IVIM parameters were acquired at 0, 12 and 24weeks after injection of streptozotocin using a range of b values from 0 to 1200s/mm2. DTI parameters were obtained using 12 diffusion directions and lower b values of 0, 100 and 400s/mm2. DTI and IVIM parameters were obtained using region of interests drawn over the renal parenchyma. Histopathological analysis of the right kidney was performed in all mice. Results were analyzed using an unpaired t-test with P<0.05 considered statistically significant.

RESULTS

Renal cortex fractional anisotropy (FA) was significantly lower in the diabetes group at week 12 as compared with the control group. Renal cortex apparent diffusion coefficient and tissue diffusivity were significantly higher in the diabetes group at week 12 compared with the control group at 12weeks. Blood flow was significantly decreased at the renal medulla at 24weeks. Histopathological analysis confirmed fibrosis in the diabetes group at 24weeks.

CONCLUSION

FA is significantly reduced in diabetic nephropathy. FA might serve a potential role in the detection and therapy monitoring of early diabetic nephropathy.

Mesenchymal cell effect on the immune response in renovascular hypertension (INC1P.352)

Atherosclerotic renal artery sclerosis (RAS) is a significant public health concern, affecting 7% of the population over 65 years old and conveying an increased risk for cardiovascular as well as renal disease. Recent reports have failed to show a benefit of renal artery stenting to treat RAS. We tested the hypothesis that mesenchymal stem cells (MSC) slow the progression of renal injury by reducing inflammation. MSCs were isolated and cultured from murine adipocyte tissue and injected via the carotid artery into the animals 4 weeks after inducing RAS, a time at which the stenotic kidney has undergone severe atrophy. Conjugated microsphere labeling and flow cytometry confirmed that the MSCs migrate to the stenotic kidney. Half of the treatment group demonstrated a 90% reduction in atrophy and significantly lower level of regulatory T cell (Treg) infiltration while the other half demonstrated no change when compared to vehicle treated RAS mice. Array analysis showed a significant down-regulation of NOS2 (M1 macrophages), RORc (Th 17 cells), and CCR4 (associated with M1 macrophages) within those mice with low renal atrophy. The results suggest that under certain conditions, MSCs have a possible effect on the inflammatory environment present in RAS mice. Future studies will determine whether intervention prior to development of severe atrophy will increase therapeutic efficacy of MSC.

Abstract 523: Diabetes Promotes the Development of Aortic Aneurysm in Mice with Hypertension

Introduction: The estimated prevalence of diabetes mellitus (DM) is 8.4% among adults in the U.S. Cardiovascular disease is a major complication of DM. We have observed that diabetic mice, but not non-diabetic mice, undergoing 2kidney-1clip (2K1C) surgery inducing renovascular hypertension had high mortality attributed to ruptured aortic aneurysm. However, the effect of diabetes on formation of aortic aneurysm remains unclear.

Method: In our previous experiment, 163 mice were divided into 4 groups: leptin KO 2K1C (db 2K1C, n=52), leptin KO Sham (db Sham, n=20), wild type 2K1C (dbc 2K1C, n=62), and wild type Sham (dbc Sham, n=29), respectively. We found that 42% (22/52) of db 2K1C died, from ruptured aortic aneurysms examined by gross examination, within 120 days, while others survived 100%. In this study, available H&E aortic sections of survived mice (n=74): db 2K1C (n=30), db Sham (n=15), dbc 2K1C (n=20), and dbc Sham (n=9) were examined 2K1C surgery in a blinded fashion. Aortic lesions defined as necrosis, thrombosis and dropped-out smooth muscle cells, which are signs of early formation of aortic aneurysm, were identified. Inflammation was graded as mild, moderate and severe inflammation.

Result: The db 2K1C mice had a significantly greater aortic lesions (16/30, 53%) compared to the db Sham (13/15, 20%); and dbc 2K1C mice (1/20, 5%), p=0.002 and 0.0001, respectively. The number of aortic lesions in the dbc 2K1C group was not statistically different from that of the dbc Sham group (p=0.5). Similarly, the number of aortic lesions in the db Sham group was not statistically different from that of the dbc Sham group (0/9, 0%), p=0.125. Moderate-to-severe inflammation in the tunica media was more prevalence in db mice than the dbc mice.

Conclusion: We report for the first time an increased incidence of aortic lesions in db 2K1C compared to dbc and sham groups. This finding suggests that diabetes contributes to aortic aneurysm formation in mice with renal artery stenosis, potentially due to induction of inflammation. Further studies to confirm a mechanism are warranted.

Abstract 521: Cardiovascular Phenotype in Mice with Renovascular Hypertension and Type II Diabetes

Background: Combined renovascular hypertension (RVH) and type II diabetes (DM II) are a major health problem. Both share common risk factors and contribute to cardiovascular morbidity and mortality. We recently observed a high mortality rate in DM II mice (dbdb) with RVH.

Purpose: We sought to determine the interactions between renovascular hypertension and DM II on the cardiovascular phenotype in dbdb mice with RVH.

Methods and Materials: RVH was established by placing a polytetrafluoroethylene cuff on the right renal artery of C57BL/KS (wild type, WT) or dbdb mice.

We divided the mice into four groups: WT sham, WT type RAS, dbdb sham, dbdb RAS. We examined the blood pressure, plasma angiotensin I, renin, heart weight and myocyte diameter. Histologic parameters including inflammation, necrosis and fibrosis were assessed semiquantitively.

Results: Blood pressure, Renin, Plasma angiotensin I: RAS produced a similar elevation in systolic blood pressure (SBP), renin mRNA expression, and plasma angiotensin I content in WT and dbdb mice with RAS.

Heart weight: Despite similar elevation in SBP, db/db RAS mice showed a greater increase in heart weight than WT RAS mice (163.7 +/- 6.4 mmHg vs 145.7 +/- 2.3; n=23).. Similar trends were observed on normalization of the heart weight to tibial length.

Cardiac myocyte diameter: Cardiac myocyte diameter in WT RAS (n=26) was significantly higher than in WT sham (n=15; 16.4 ± 0.3 vs. 15.0 ± 0.3 μm, p=0.0031). Myocyte diameter was higher in dbdb RAS mice (n=19, 14.76 ± 0.35) than dbdb sham (15.94 ± 0.29 μm, p= 0.0126). However, myocyte diameter was similar in dbdb RAS and WT RAS mice (16.4 ± 0.3 vs. 15.9 ± 0.3 μm, p=0.3).

Histology: Sham groups had no inflammation (INF) or necrosis (NEC). Interstitial fibrous tissue was increased in dbdb RAS mice (28% by area) vs WT RAS (19% by area). Dbdb RAS mice had more severe INF (severe in 18%, mild in 82%) than WT RAS (severe in 0%, jild in 12%). Severe NEC was found in 32.1% of dbdb compared to 11.5% of WT RAS.

Conclusion: The histologic changes and hypertrophy of the heart superimpose in dbdb RAS compared to WT RAS. This indicates that the risk of cardiovascular morbidity and mortality increases synergisticly in the presence of DM II and RVH.

NLRP3 deficiency reduces renal atrophy in renovascular hypertension (HUM1P.306)

Renovascular hypertension (RVH) affects up to 7% of individuals over 65 years of age. We have previously demonstrated that induction of oxidative stress is an early event in the development of RVH that leads to development of inflammation and renal atrophy. NLRP3 is one of the most well-known sensors of oxidative stress. However, the role of NLRP3 in the development of RVH and subsequent end-organ damage is not well understood. We therefore sought to test the hypothesis that inhibition of NLRP3 activation protects the heart and the kidneys of mice subjected to RVH. In accordance with our previous observations, wild type (WT) mice subjected to RVH developed 26±6% of renal atrophy within 1 week following cuff placement that progressed to almost 100% by 4 weeks. In contrast, although NLRP3-/- mice (KO) subjected to RVH developed similar degree of atrophy to their age-matched WT in the first week (29 ± 17 vs. 39 ± 20), the atrophy did not progress when evaluated at 4 weeks (29 ± 13 vs. 78 ± 10, p=0.013). Histologic evaluation of renal cortex of KO mice showed no significant interstitial infiltration with CD3+ T cells or F4/80+ macrophages. In addition, KO mice developed no cardiac hypertrophy, no cardiac fibrosis, or aortic lesion despite similar elevation in systolic blood pressure to the WT mice. We propose that NLRP3 activation plays a critical role in the development of renal atrophy in mice subjected to RVH and represent a potential therapeutic target.

The stenotic kidney of Rag1 mice subjected to 2K1C hypertension is protected from atrophy (P3078)

Renal artery stenosis is a common finding in patients with cardiovascular disease. Recent studies have provided evidence that innate immunity plays a critical role in the development of chronic renal disease in renovascular hypertension. We have previously demonstrated that interstitial infiltration of lymphocytes is an early event in the development of renal atrophy in the 2K1C model of renovascular hypertension. We therefore sought to test the hypothesis that lymphocytes play a role in the development of progressive atrophy/fibrosis in this model. We subjected mice to renal artery stenosis through placement of a polytetrafluoroethylene cuff on the right renal artery. In accordance with our previous observations, wild type mice subjected to RAS developed renal atrophy within 2 weeks following placement of the cuff (70.5 +/- 11.9%). Chemokine expression in renal cortex of the stenotic kidney reflected predominantly a Th1 response (STAT1, STAT4, TBX21); CCL2, CCL17, CCL12, and TNF mRNA expression were also upregulated, but not IL-6 and IL-10. In striking contrast to wild type mice, Rag1 mice developed significantly less atrophy (23.1 +/- 10.4, p&lt;0.0037 vs wild type). Unlike wild type mice, histologic evaluation of renal cortex of Rag1 mice showed no significant interstitial infiltration with CD3+ T cells or F4/80+ macrophages. We propose that T cell-mediated inflammation plays a critical role in the development of renal atrophy in 2K1C mice.

A Phase 1 dose-finding and pharmacodynamic study of rapamycin in combination with bevacizumab in patients with unresectable hepatocellular carcinoma

BACKGROUND & AIMS

Preclinical studies have demonstrated the additive effect of rapamycin with bevacizumab for hepatocellular carcinoma treatment. We conducted a Phase 1 study to evaluate the safety and pharmacokinetics of the combination in patients with hepatocellular carcinoma.

METHODS

Adult participants with advanced hepatocellular carcinoma received intravenous bevacizumab (5mg/kg every 14 days) and oral rapamycin (1-6 mg/day; 3+3 dose escalation design). Computed tomography assessed tumour response and treatment safety. Pharmacokinetics assessment established rapamycin blood concentrations pre- and post-dose. Dynamic contrast-enhanced computed tomography analysed the tumour region for blood flow, permeability surface area product, fractional intravascular blood volume and extracellular-extravascular volume.

RESULTS

Twenty-four participants were treated. There were two dose limiting toxicities with rapamycin 5mg: grade 3 thrombocytopenia and grade 3 mucositis. The maximally tolerated dose of rapamycin was 4 mg. Adverse events (grade 1-2) included hyperglycaemia (83%), thrombocytopenia (75%), fatigue (46%), mucositis (46%), anorexia (42%), diarrhoea (33%) and proteinuria (12.5%). Of 20 evaluable participants, one reached complete response that lasted 4.5 months, two reached partial response, 14 reached stable disease and three had progressive disease. Median overall survival was 9.4 months; progression-free survival was 5.5 months. Dose level and steady state area under the concentration time curve for hour zero to infinity of rapamycin correlated inversely with blood flow rate and change in permeability-surface area. After 22 days of treatment, there were significant reductions from baseline in blood flow rate, permeability-surface area and fractional intracellular blood volume.

CONCLUSIONS

The recommended Phase 2 dose of rapamycin is 4 mg in combination with bevacizumab. Evidence of anti-vascular activity was observed together with promising clinical activity.

High temporal resolution dynamic contrast-enhanced MRI at 7 Tesla: a feasibility study with mouse liver model

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been widely applied to evaluate microcirculatory parameters in clinical settings. However, pre-clinical studies involving DCE-MRI of small animals remain challenging with the requirement for high spatial and temporal resolution for quantitative tracer kinetic analysis. This study illustrates the feasibility of applying a high temporal resolution (2 s) protocol for liver imaging in mice by analyzing the DCE-MRI datasets of mice liver with a dual-input two-compartment tracer kinetic model. Phantom studies were performed to validate the T(1) estimates derived by the proposed protocol before applying it in mice studies. The DCE-MRI datasets of mice liver were amendable to tracer kinetic analysis using a dual-input two-compartment model. Estimated micro-circulatory parameters were consistent with liver physiology, indicating viability of applying the technique for pre-clinical drug developments.

Dynamic contrast-enhanced MRI of neuroendocrine hepatic metastases: A feasibility study using a dual-input two-compartment model

Neuroendocrine hepatic metastases exhibit various contrast uptake enhancement patterns in dynamic contrast-enhanced MRI. Using a dual-input two-compartment distributed parameter model, we analyzed the dynamic contrast-enhanced MRI datasets of seven patient study cases with the aim to relate the tumor contrast uptake patterns to parameters of tumor microvasculature. Simulation studies were also performed to provide further insights into the effects of individual microcirculatory parameter on the tumor concentration-time curves. Although the tumor contrast uptake patterns can be influenced by many parameters, initial results indicate that hepatic blood flow and the ratio of fractional vascular volume to fractional interstitial volume may potentially distinguish between the patterns of neuroendocrine hepatic metastases.

Acute myocardial ischaemia in the anaesthetised pig: local catecholamine release and its relation to ventricular fibrillation

In anaesthetised open-chest pigs, sequential myocardial samples were obtained before and after occlusion of the distal half of the LAD. These samples were analysed histofluorimetrically to determine the density of catecholamine containing neurones in each sample (quantified morphometrically), and radioenzymatically for total tissue noradrenaline content. Following coronary artery occlusion, 75% of the animals (24 out of 32) died in ventricular fibrillation in the first 30 min, the other 25% (8/32) survived the first 60 min of myocardial ischaemia. Coronary artery occlusion led to a significant reduction in the density of fluorescing fibres in the ischaemic myocardium of animals which fibrillated (from 1.25 +/- 0.2% to 0.67 +/- 0.10% at 15 min) whereas in the survivors there was no significant change in fluorescing area during the course of the experiment. Animals which fibrillated had a significant reduction in tissue noradrenaline concentration of the ischaemic myocardium (from an initial concentration of 612 +/- 72 to 402 +/- 64 ng/g ww) within the first 5 min of ischaemia. It is concluded that in this model of myocardial ischaemia, the development of ventricular fibrillation in the early phase seems to be related to the release of noradrenaline from the sympathetic neurones after the onset of myocardial ischaemia.