Uroliths composed of antiviral compound GS-441524 in 2 cats undergoing treatment for feline infectious peritonitis.

Feline infectious peritonitis (FIP) historically has been a fatal disease in cats. Recent unlicensed use of antiviral medication has been shown to markedly improve survival of this infection. An 8-month-old female spayed domestic short-haired cat undergoing treatment for presumptive FIP with the antiviral nucleoside analog GS-441524 developed acute progressive azotemia. Abdominal ultrasound examination identified multifocal urolithiasis including renal, ureteral, and cystic calculi. Unilateral ureteral obstruction progressed to suspected bilateral ureteral obstruction and subcutaneous ureteral bypass (SUB) was performed along with urolith removal and submission for analysis. A 2-year-old male neutered domestic medium-haired cat undergoing treatment for confirmed FIP with GS-441524 developed dysuria (weak urine stream, urinary incontinence, and difficulty expressing the urinary bladder). This cat also was diagnosed sonographically with multifocal urolithiasis requiring temporary tube cystostomy after cystotomy and urolith removal. In both cases, initial urolith analysis showed unidentified material. Additional testing confirmed the calculi in both cats to be 98% consistent with GS-441524. Additional clinical studies are required to determine best screening practices for cats presented for urolithiasis during treatment with GS-441524.

Effect of gabapentin on ambulatory, direct, systemic arterial blood pressure in apparently healthy cats in the at-home and in-clinic environments.

OBJECTIVES: Situational increases in blood pressure (BP) frequently confound the accurate diagnosis of pathological systemic hypertension in cats. The objective of this study was to investigate the effect of gabapentin on direct, ambulatory systolic arterial BP (SBP) in cats in at-home and in-clinic environments. METHODS: Six adult purpose-bred cats with surgically implanted femoral artery telemetric BP-sensing catheters were administered 100 mg of gabapentin or a placebo orally in two randomized, masked, crossover study phases. In the first, direct BP was measured continuously in undisturbed cats for 24 h before (at-home baseline) and 4 h after administration of study drug. The mean SBP after administration of the drug was compared between treatments. In the second study period, cats were administered gabapentin or placebo 90 mins before transport to a clinic, where direct BP was measured continuously during a simulated veterinary visit that included an indirect BP measurement session. Changes in mean direct SBP relative to the 24-h at-home pre-treatment period were calculated for each of one waiting room and two examination-room periods, and compared between treatments. Concurrent in-clinic direct and indirect SBP measurements were compared within-cat. Data were compared using linear mixed models. RESULTS: Direct SBP data from one cat were excluded due to implant failure. There were no differences in at-home or in-clinic SBP between treatment groups, with large inter-individual variability. Cats in both treatment groups experienced in-clinic increases in direct SBP relative to at-home baseline (range 11-50 and 10-52 mmHg in placebo- and gabapentin-treated cats, respectively). Across all visits, direct SBP was 15.6 mmHg higher than indirect SBP (P <0.001). No effects of treatment on difference between direct and indirect SBP were identified. CONCLUSIONS AND RELEVANCE: Significant effects of gabapentin on direct SBP were not identified, though a type II error is possible. Situational increases cannot be excluded in gabapentin-treated cats with high SBP.

Acute kidney injury is common in dogs with septic peritonitis and is associated with increased mortality.

OBJECTIVE: To identify the frequency of and risk factors for acute kidney injury (AKI) in dogs undergoing abdominal surgery for septic peritonitis, and to evaluate outcome and kidney-related risk factors for survival to discharge in those dogs. ANIMALS: 77 dogs that underwent abdominal surgery for septic peritonitis. METHODS: Medical records of dogs that underwent surgery for septic peritonitis from 2012 through 2022 were reviewed. Data regarding signalment, clinical and biochemical findings at presentation, blood creatinine concentration throughout hospitalization, surgery characteristics, postoperative monitoring, and outcome were collected. Dogs were classified based on occurrence of AKI and whether they presented with or developed AKI in-hospital. Perioperative risk factors were evaluated, and outcomes were compared with univariable logistic regression. RESULTS: 31 dogs (40.3%) had AKI diagnosed; 18/77 (23.4%) dogs presented with AKI, 11 (61.1%) of which had it postoperatively, and 13/77 (16.9%) dogs developed AKI postoperatively. Significant factors for presenting with AKI included increasing baseline respiratory rate (OR 2.5 for every 10 beats per minute higher), decreasing systolic blood pressure (OR 0.8 for every 10 mm Hg higher), and increasing body condition score (OR 2.2 for every score greater). No significant factors for developing AKI postoperatively were identified after multiple comparisons adjustment. Sixteen dogs (20.8%) did not survive to discharge; 12 (75.0%) had AKI and 4 (25.0%) did not. Dogs with AKI had decreased odds of survival to discharge (OR 0.2). CLINICAL RELEVANCE: AKI was common in dogs with septic peritonitis and was a significant risk factor for survival to discharge. Clinical surveillance of AKI is critical in this population.

A remnant kidney surgery model in cats induces acute and chronic outcomes that mimic spontaneous chronic kidney disease.

OBJECTIVE: To report acute and chronic outcomes of cats with chronic kidney disease (CKD) induced by a remnant kidney model. ANIMALS: 32 purpose-bred cats (n = 15 female, n = 17 male). PROCEDURES: Cats underwent a 2-stage reduction in renal mass through partial arterial ligation of 1 kidney (day 28) and delayed contralateral nephrectomy (day 0), targeting an 11/12th functional nephrectomy. Acute (days -28 - 29) survival and renal function parameters were compared over time, and the latter were evaluated as predictors for acute mortality. Chronic (days 30 to >1,100) survival, renal function, and morphology were described. RESULTS: Acutely, renal function deteriorated in all cats (mean ± SD baseline and day 28 serum creatinine mean concentration, 1.13 ± 0.23 mg/dL and 3.03 ± 1.20 mg/dL, respectively; P < .001; and GFR, 3.22 mL/min/kg ± 0.12 and 1.21 mL/min/kg ± 0.08, respectively; P < .001). Seven (22%) cats were euthanized after because of clinical signs of uremia after contralateral nephrectomy. Prenephrectomy renal function tests were not significant indicators for survival during this acute phase. Twenty-five cats entered the chronic phase. Ten cats were euthanized at a median of 163 days from nephrectomy because of progressive renal dysfunction. Median survival times were significantly different when stratified by acute kidney injury grade at day 29. Cats in the chronic phase had clinical courses similar to cats with naturally occurring CKD, and most (13/15) were in CKD stage 2. CLINICAL RELEVANCE: The remnant kidney model is effective at reducing kidney function to an extent that mimics important characteristics of spontaneous CKD in cats.

Cross-sectional characterization of renal function in cats with caudal stomatitis.

OBJECTIVES: The objective of the study was to compare renal functional biomarkers in cats and in caudal stomatitis (CS) and in age-matched control cats. METHODS: A cross-sectional, case-control study was conducted on 44 client-owned cats with CS that were prospectively enrolled and evaluated for a Comprehensive Oral Health Assessment and Treatment at one of four institutions. Renal function was assessed with measurement of serum creatinine, urea nitrogen, serum symmetric dimethylarginine, urinalysis, urine protein:creatinine ratio and urine protein electrophoresis. Affected gingiva was biopsied to confirm the diagnosis of stomatitis. Renal biochemical analyses from the experimental group were compared with those of 44 age-matched controls without CS enrolled prospectively or retrospectively after presenting to the primary institution for routine healthcare. Control cats were included if they were clinically stable, their chronic illnesses were well managed and minimal dental disease was present on examination. Renal biomarkers were compared between groups using a t-test or the Mann-Whitney U-test. Frequency of azotemia, proteinuria and the clinical diagnosis of renal disease were compared using Fisher's exact test. RESULTS: Relative to the control group, cats in the CS group had significantly lower serum creatinine (P <0.001) and albumin concentrations (P <0.001), urine specific gravity (P = 0.024) and hematocrit (P = 0.003), and higher serum phosphorus (P <0.001), potassium (P <0.001) and globulin concentrations (P <0.001), white blood cell count (P <0.001) and urine protein:creatinine ratio (P = 0.009). There were no significant differences in serum symmetric dimethylarginine or urea nitrogen concentrations. No clinically significant findings were noted on urine protein electrophoresis. There were no significant differences in the frequency of azotemia, proteinuria or renal disease categories between the two groups. CONCLUSIONS AND RELEVANCE: The present study does not demonstrate a significant difference in the frequency of kidney disease between cats with and without CS. Longitudinal evaluation is warranted to investigate the relationship between renal disease and CS.

MicroRNAs are differentially expressed in the serum and renal tissues of cats with experimentally induced chronic kidney disease: a preliminary study.

OBJECTIVE: To identify differentially expressed microRNA in the serum and renal tissues of cats with experimentally induced chronic kidney disease (CKD). SAMPLE: Banked renal tissues and serum from 4 cats. PROCEDURES: Cats previously underwent 90-minute unilateral ischemia with delayed contralateral nephrectomy 3 months after ischemia. Tissues were collected from the contralateral kidney at the time of nephrectomy and from the ischemic kidney 6 months after nephrectomy (study end). Serum was collected prior to ischemia (baseline serum) and at study end (end point serum). Total RNA was isolated from tissues and serum, and microRNA sequencing was performed with differential expression analysis between the contralateral and ischemic kidney and baseline and end point serum. RESULTS: 20 microRNAs were differentially expressed between ischemic and contralateral kidneys, and 52 microRNAs were differentially expressed between end point and baseline serum. Five microRNAs were mutually differentially expressed between ischemic and contralateral kidneys and baseline and end point serum, with 4 (mir-21, mir-146, mir-199, and mir-235) having increased expression in both the ischemic kidney and end point serum and 1 (mir-382) having increased expression in the ischemic kidney and decreased expression in end point serum. Predicted target search for these microRNA revealed multiple genes previously shown to be involved in the pathogenesis of feline CKD, including hypoxia-inducible factor-1α, transforming growth factor-ß, hepatocyte growth factor, fibronectin, and vascular endothelial growth factor A. CLINICAL RELEVANCE: MicroRNAs were differentially expressed after CKD induction in this preliminary study. Regulation of renal fibrosis in feline CKD may occur through microRNA regulation of mRNAs of pro- and anti-fibrotic genes.

Engineering Modular Half-Antibody Conjugated Nanoparticles for Targeting CD44v6-Expressing Cancer Cells.

Gastric cancer (GC) remains a major cause of death worldwide mainly because of the late detection in advanced stage. Recently, we proposed CD44v6 as a relevant marker for early detection of GC, opening new avenues for GC-targeted theranostics. Here, we designed a modular nanoscale system that selectively targets CD44v6-expressing GC cells by the site-oriented conjugation of a new-engineered CD44v6 half-antibody fragment to maleimide-modified polystyrene nanoparticles (PNPs) via an efficient bioorthogonal thiol-Michael addition click chemistry. PNPs with optimal particle size (200 nm) for crossing a developed biomimetic CD44v6-associated GC stromal model were further modified with a heterobifunctional maleimide crosslinker and click conjugated to the novel CD44v6 half-antibody fragment, obtained by chemical reduction of full antibody, without affecting its bioactivity. Collectively, our results confirmed the specific targeting ability of CD44v6-PNPs to CD44v6-expressing cells (1.65-fold higher than controls), highlighting the potential of CD44v6 half-antibody conjugated nanoparticles as promising and clinically relevant tools for the early diagnosis and therapy of GC. Additionally, the rational design of our nanoscale system may be explored for the development of several other nanotechnology-based disease-targeted approaches.

Evaluation of profibrotic gene transcription in renal tissues from cats with naturally occurring chronic kidney disease.

BACKGROUND: Increased gene transcription of hypoxia-induced mediators of fibrosis in renal tissue has been identified in experimentally induced, ischemic chronic kidney disease (CKD). OBJECTIVE: To characterize hypoxia-induced profibrotic pathways in naturally occurring CKD in cats. ANIMALS: Twelve client-owned cats with CKD and 8 healthy control cats. METHODS: In this prospective, cross-sectional study, bilateral renal tissue samples were assessed histologically for inflammation, tubular atrophy, and fibrosis, and by reverse transcription-quantitative PCR for characterization of transcript levels of hypoxia-inducible factor-1α (HIF1A), matrix metalloproteinases-2 (MMP2), -7 (MMP7), and -9 (MMP9), tissue inhibitor of metalloproteinase-1 (TIMP1), transforming growth factor-ß1 (TGFB1), and vascular endothelial growth factor-A (VEGFA). Linear mixed models were used to compare gene transcription between diseased and healthy kidneys, and to examine the association between transcript levels and serum creatinine concentration for all cats, and between transcript levels and histologic scores of diseased kidneys. RESULTS: Kidneys from cats with CKD had significantly higher transcript levels of HIF1A, MMP2, MMP7, MMP9, TIMP1, and TGFB1 (all P < .001), and lower levels of VEGFA (P = .006) than those from control cats. Transcript levels of MMP7 (P = .05) and TIMP1 (P = .005) were positively associated with serum creatinine in cats with CKD, but not in control cats. In diseased kidneys, transcript levels of MMP2 (P = .002), MMP7 (P = .02), and TIMP1 (P = .02) were positively, whereas those of VEGFA (P = .003) were negatively, associated with histologic score severity. CONCLUSION AND CLINICAL SIGNIFICANCE: Evaluation of the expression of the corresponding proteins in larger populations could identify therapeutic targets and/or biomarkers of tubulointerstitial fibrosis in cats.

Profibrotic gene transcription in renal tissues from cats with ischemia-induced chronic kidney disease.

OBJECTIVE: To characterize transcription of profibrotic mediators in renal tissues of cats with ischemia-induced chronic kidney disease (CKD). SAMPLE: Banked renal tissues from 6 cats with experimentally induced CKD (RI group) and 8 healthy control cats. PROCEDURES: For cats of the RI group, both kidneys were harvested 6 months after ischemia was induced for 90 minutes in 1 kidney. For control cats, the right kidney was evaluated. All kidney specimens were histologically examined for fibrosis, inflammation, and tubular atrophy. Renal tissue homogenates underwent reverse transcription quantitative PCR assay evaluation to characterize gene transcription of hypoxia-inducible factor-1α (HIF-1α), matrix metalloproteinase (MMP)-2, MMP-7, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), transforming growth factor-ß1, and vascular endothelial growth factor A. Gene transcription and histologic lesions were compared among ischemic and contralateral kidneys of the RI group and control kidneys. RESULTS: Ischemic kidneys had greater transcript levels of MMP-7, MMP-9, and transforming growth factor-ß1 relative to control kidneys and of MMP-2 relative to contralateral kidneys. Transcription of TIMP-1 was upregulated and that of vascular endothelial growth factor A was downregulated in ischemic and contralateral kidneys relative to control kidneys. Transcription of HIF-1α did not differ among kidney groups. For ischemic kidneys, there were strong positive correlations between transcription of HIF-1α, MMP-2, MMP-7, and TIMP-1 and severity of fibrosis. CONCLUSIONS AND CLINICAL RELEVANCE: Transcription of genes involved in profibrotic pathways remained altered in both kidneys 6 months after transient renal ischemia. This suggested that a single unilateral renal insult can have lasting effects on both kidneys.

Bioengineering a novel 3D in vitro model of gastric mucosa for stomach permeability studies.

The field of stomach-directed therapeutics and diagnosis is still hampered by the lack of reliable in vitro models that closely mimic the gastric mucosa where gastric cancer cells are generally confined. Here we propose a rapid, complex, and innovative 3D in vitro model of the gastric mucosa, by extending a conventional gastric monolayer model to an inner stratum of the mucosa - the lamina propria. The developed model comprises normal stomach fibroblasts embedded in a 3D RGD-modified alginate hydrogel prepared on the basolateral side of a Transwell® insert, mimicking the extracellular matrix and cellular component of the lamina propria, onto which a moderately differentiated adenocarcinoma stomach cell line (MKN74) was seeded, reproducing the physiological conditions of the gastric barrier. The integrity and functionality of the in vitro model was evaluated through permeability studies of FITC-dextran and 200 nm fluorescent polystyrene nanoparticles at gastric conditions. Nanoparticle transport was pH-dependent and strongly impacted by the biomimetic lamina propria, highlighting that a gastric extracellular matrix (ECM)-like microenvironment should be integrated in an in vitro permeability model to be adopted as a reliable evaluation tool of innovative therapeutics and diagnosis of gastric diseases. STATEMENT OF SIGNIFICANCE: Current in vitro models of the gastric mucosa are limited to simplistic 2D cell culture systems, which ignore the dimensionality of the stomach wall and make it difficult to reliably test new therapeutic approaches to gastric pathologies. By combining stomach fibroblasts embedded within a 3D RGD-modified alginate hydrogel and epithelial gastric cancer cells in a Transwell® system, we established a new biomimetic model of the stomach mucosa. Epithelial cells recreate the gastric epithelium, while the cell-laden 3D hydrogel recapitulates both the cellular composition and dimensionality of the extracellular matrix of gastric lamina propria. This cellularized 3D model stands as a promising evaluation platform to assist the development of new strategies for the treatment and diagnosis of gastric diseases.

CD44v6 increases gastric cancer malignant phenotype by modulating adipose stromal cell-mediated ECM remodeling.

CD44, an abundantly expressed adhesion molecule, and its alternative splice variants have been associated with tumorigenesis and metastasis. In the context of gastric cancer (GC), de novo expression of CD44 variant 6 (CD44v6) is found in more than 60% of GCs, but its role in the pathogenesis and progression of this type of cancer remains unclear. Using a combination of media conditioning experiments and decellularized extracellular matrices (ECMs), this study investigates the hypothesis that CD44v6 overexpression enhances tumor cell malignant behavior by modulating stromal cell-mediated ECM remodeling. Our findings indicate that soluble factors secreted by CD44v6 expressing GC cells particularly increase proliferation and myofibroblastic differentiation of adipose stromal cells (ASCs). These changes in ASC phenotype mediate the deposition of fibrotic/desmoplastic ECM that, in turn, stimulates GC proliferation and inhibits GC clustering. Pharmacological inhibition of matrix metalloproteinase (MMP) activity in tumor cells abrogated matrix-induced changes in tumor cell malignant behavior. Additionally, studies in mice confirmed the pathological relevance of CD44v6 expression and consequential changes in ECM remodeling to gastric tumorigenesis in vivo. Collectively, these results indicate a direct link between CD44v6, ECM remodeling, and GC malignant behavior opening new insights into potential CD44v6-targeted therapies.

Abdominal ultrasonographic findings in acromegalic cats.

OBJECTIVES: Acromegaly is increasingly recognized as a cause of insulin resistance in cats with diabetes mellitus (DM). The objective of this study was to determine if ultrasonographic changes in selected abdominal organs of acromegalic cats could be used to raise the index of suspicion for this condition. METHODS: In this retrospective case-control study, medical records of cats presenting to North Carolina State University or Colorado State University from January 2002 to October 2012 were reviewed. Cats were included in the acromegaly group if they had insulin-resistant DM with increased serum insulin-like growth factor (IGF-1) concentrations and had an abdominal ultrasound examination performed with report available. A control group included age-matched cats that had abdominal ultrasound examination performed for investigation of disease unlikely to involve the kidneys, adrenal glands, pancreas or liver. RESULTS: Twenty-four cats were included in each group. IGF-1 concentrations in the acromegaly group ranged from >148 to 638 nmol/l. When compared with age-matched controls, cats with acromegaly demonstrated significantly increased median left and right kidney length, significantly increased median left and right adrenal gland thickness, and significantly increased median pancreatic thickness. Hepatomegaly and bilateral adrenomegaly were reported in 63% and 53% of acromegalic cats, respectively, and in none of the controls. Pancreatic abnormalities were described in 88% of the acromegalic cats and 8% of the controls. CONCLUSIONS AND RELEVANCE: These findings indicate that compared with non-acromegalic cats, age-matched acromegalic patients have measurably larger kidneys, adrenal glands and pancreas. Diagnostic testing for acromegaly should be considered in poorly regulated diabetic cats exhibiting organomegaly on abdominal ultrasound examination.