The Role of Circulating Tumor Cells as a Liquid Biopsy for Cancer: Advances, Biology, Technical Challenges, and Clinical Relevance

Cancer remains a leading cause of mortality worldwide, with metastasis significantly contributing to its lethality. The metastatic spread of tumor cells, primarily through the bloodstream, underscores the importance of circulating tumor cells (CTCs) in oncological research. As a critical component of liquid biopsies, CTCs offer a non-invasive and dynamic window into tumor biology, providing invaluable insights into cancer dissemination, disease progression, and response to treatment. This review article delves into the recent advancements in CTC research, highlighting their emerging role as a biomarker in various cancer types. We explore the latest technologies and methods for CTC isolation and detection, alongside novel approaches to characterizing their biology through genomics, transcriptomics, proteomics, and epigenetic profiling. Additionally, we examine the clinical implementation of these findings, assessing how CTCs are transforming the landscape of cancer diagnosis, prognosis, and management. By offering a comprehensive overview of current developments and potential future directions, this review underscores the significance of CTCs in enhancing our understanding of cancer and in shaping personalized therapeutic strategies, particularly for patients with metastatic disease.

Testing spatial working memory in pigs using an automated T-maze

Pigs are an important large animal model for translational clinical research but underutilized in behavioral neuroscience. This is due, in part, to a lack of rigorous neurocognitive assessments for pigs. Here, we developed a new automated T-maze for pigs that takes advantage of their natural tendency to alternate. The T-maze has obvious cross-species value having served as a foundation for cognitive theories across species. The maze (17' × 13') was constructed typically and automated with flanking corridors, guillotine doors, cameras, and reward dispensers. We ran nine pigs in (1) a simple alternation task and (2) a delayed spatial alternation task. Our assessment focused on the delayed spatial alternation task which forced pigs to wait for random delays (5, 60, 120, and 240 s) and burdened spatial working memory. We also looked at self-paced trial latencies, error types, and coordinate-based video tracking. We found pigs naturally alternated but performance declined steeply across delays (R2 = 0.84). Self-paced delays had no effect on performance suggestive of an active interference model of working memory. Positional and head direction data could differentiate subsequent turns on short but not long delays. Performance levels were stable over weeks in diverse strains and sexes, and thus provide a benchmark for future neurocognitive assessments in pigs.

Sex and estrous cycle in memory for sequences of events in rats

The ability to remember sequences of events is fundamental to episodic memory. While rodent studies have examined sex and estrous cycle in episodic-like spatial memory tasks, little is known about these biological variables in memory for sequences of events that depend on representations of temporal context. We investigated the role of sex and estrous cycle in rats during training and testing stages of a cross-species validated sequence memory task (Jayachandran et al., 2019). Rats were trained on a two four-odor sequence memory task delivered on opposite ends of a linear track. Training occurred in six successive stages starting with learning to poke in a nose-port for ≥ 1.2 s; eventually demonstrating sequence memory by holding their nose in the port ≥ 1 s for in-sequence odors and < 1 s for out-of-sequence odors. Performance was analyzed across sex and estrous cycle (proestrus, estrus, metestrus, and diestrus), the latter being determined by cellular composition of a daily vaginal lavage. We found no evidence of sex differences in asymptotic sequence memory performance, similar to humans performing an analogous task (Reeders et al., 2021). Likewise, no differences in sequence memory performance were found across the estrous cycle. Some caveats are that males acquired out-of-sequence trials faster during training with a 3-odor sequence, but this apparent advantage did not carry over to the 4-odor sequence. Additionally, males had shorter poke times overall which seem consistent with a decreased overall response inhibition because they occurred regardless of sequence demands. Together, these results suggest sex and estrous cycle are not major factors in sequence memory capacities. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A Zebrafish Model of Metastatic Colonization Pinpoints Cellular Mechanisms of Circulating Tumor Cell Extravasation

Metastasis is a multistep process in which cells must detach, migrate/invade local structures, intravasate, circulate, extravasate, and colonize. A full understanding of the complexity of this process has been limited by the lack of ability to study these steps in isolation with detailed molecular analyses. Leveraging a comparative oncology approach, we injected canine osteosarcoma cells into the circulation of transgenic zebrafish with fluorescent blood vessels in a biologically dynamic metastasis extravasation model. Circulating tumor cell clusters that successfully extravasated the vasculature as multicellular units were isolated under intravital imaging (n = 6). These extravasation-positive tumor cell clusters sublines were then molecularly profiled by RNA-Seq. Using a systems-level analysis, we pinpointed the downregulation of KRAS signaling, immune pathways, and extracellular matrix (ECM) organization as enriched in extravasated cells (p < 0.05). Within the extracellular matrix remodeling pathway, we identified versican (VCAN) as consistently upregulated and central to the ECM gene regulatory network (p < 0.05). Versican expression is prognostic for a poorer metastasis-free and overall survival in patients with osteosarcoma. Together, our results provide a novel experimental framework to study discrete steps in the metastatic process. Using this system, we identify the versican/ECM network dysregulation as a potential contributor to osteosarcoma circulating tumor cell metastasis.

A lifetime of challenges: real-life decision outcomes in early- and late-onset suicide attempters

Background

People who have attempted suicide display suboptimal decision-making in the lab. Yet, it remains unclear whether these difficulties tie in with other detrimental outcomes in their lives besides suicidal behavior. We hypothesize that this is more likely the case for individuals who first attempted suicide earlier than later in life.

Methods

A cross-sectional case-control study of 310 adults aged ≥ 50 years (mean: 63.9), compared early- and late-onset attempters (first attempt < 55 vs. ≥ 55 years of age) to suicide ideators, non-suicidal depressed controls and non-psychiatric healthy controls. Participants reported potentially avoidable negative decision outcomes across their lifetime, using the Decision Outcome Inventory (DOI). We employed multi-level modeling to examine group differences overall, and in three factor-analytically derived domains labeled Acting Out, Lack of Future Planning, and Hassles.

Results

Psychopathology predicted worse decision outcomes overall, and in the more serious Acting Out and Lack of Future Planning domains, but not in Hassles. Early-onset attempters experienced more negative outcomes than other groups overall, in Lack of Future Planning, and particularly in Acting Out. Late-onset attempters were similar to depressed controls and experienced fewer Acting out outcomes than ideators.

Limitations

The cross-sectional design precluded prospective prediction of attempts. The assessment of negative outcomes may have lacked precision due to recall bias.

Conclusions

Whereas early-onset suicidal behavior is likely the manifestation of long-lasting decision-making deficits in several serious aspects of life, late-onset cases appear to function similarly to non-suicidal depressed adults, suggesting that their attempt originates from a more isolated crisis.

Biological Aspects of Cancer Health Disparities

Racial and ethnic disparities span the continuum of cancer care and are driven by a complex interplay among social, psychosocial, lifestyle, environmental, health system, and biological determinants of health. Research is needed to identify these determinants of cancer health disparities and to develop interventions to achieve cancer health equity. Herein, we focus on the overall burden of ancestry-related molecular alterations, the functional significance of the alterations in hallmarks of cancer, and the implications of the alterations for precision oncology and immuno-oncology. In conclusion, we reflect on the importance of estimating ancestry, improving diverse racial and ethnic participation in cancer clinical trials, and examining the intersection among determinants of cancer health disparities.

RNA splicing and aggregate gene expression differences in lung squamous cell carcinoma between patients of West African and European ancestry

OBJECTIVES

Despite disparities in lung cancer incidence and mortality, the molecular landscape of lung cancer in patients of African ancestry remains underexplored, and race-related differences in RNA splicing remain unexplored.

MATERIALS AND METHODS

We identified differentially spliced genes (DSGs) and differentially expressed genes (DEGs) in biobanked lung squamous cell carcinoma (LUSC) between patients of West African and European ancestry, using ancestral genotyping and Affymetrix Clariom D array. DSGs and DEGs were validated independently using the National Cancer Institute Genomic Data Commons. Associated biological processes, overlapping canonical pathways, enriched gene sets, and cancer relevance were identified using Gene Ontology Consortium, Ingenuity Pathway Analysis, Gene Set Enrichment Analysis, and CancerMine, respectively. Association with LUSC survival was conducted using The Cancer Genome Atlas.

RESULTS

4,829 DSGs and 267 DEGs were identified, including novel targets in NSCLC as well as genes identified previously to have relevance to NSCLC. RNA splicing events within 3 DSGs as well as 1 DEG were validated in the independent cohort. 853 DSGs and 29 DEGs have been implicated as potential drivers, oncogenes and/or tumor suppressor genes. Biological processes enriched among DSGs and DEGs included metabolic process, biological regulation, and multicellular organismal process and, among DSGs, ion transport. Overlapping canonical pathways among DSGs included neuronal signaling pathways and, among DEGs, cell metabolism involving biosynthesis. Gene sets enriched among DSGs included KRAS Signaling, UV Response, E2 F Targets, Glycolysis, and Coagulation. 355 RNA splicing events within DSGs and 18 DEGs show potential association with LUSC patient survival.

CONCLUSION

These DSGs and DEGs, which show potential biological and clinical relevance, could have the ability to drive novel biomarker and therapeutic development to mitigate LUSC disparities.

Abstract PO-128: Interrogating the role of race-related alternative splicing of SEMA3C in prostate cancer

The age-adjusted incidence and mortality rates for prostate cancer (PCa) among African American (AA) men are 1.6- and 2.4-fold greater, respectively, than among white men. These disparities likely result from a complex interplay among social, psycho-social, lifestyle, environmental, health system, and biological determinants of health. Despite the contribution of biological determinants of health, very few studies have utilized this population-based difference to identify the molecular mechanisms underlying race-related tumor aggressiveness. We have previously identified Semaphorin 3C (SEMA3C) as a novel alternatively spliced gene in PCa between AA and white patients. SEMA3C has been shown to be associated with increased cancer growth, poor prognosis in lung, breast, gastric, and ovarian cancers, and promotion of cell migration and invasion in PCa. To further study the significance of race-related skipping/inclusion of SEMA3C exon 19 in PCa cell biology, we used CRISPR/Cas9 technology to engineer a PCa cell line (DU145) expressing the SEMA3C variant skipping exon 19. Proliferation assays were performed with the established cell lines, and the SEMA3C exon 19 KO populations exhibited decreased proliferation rates, compared with the wild-type DU145 cells that express the SEMA3C variant including exon 19. These data suggest race-related alternative splicing of SEMA3C may have an impact on PCa aggressiveness in patients. Current and future experiments focus on interrogating the effect of race-related SEMA3C alternative splicing on PCa cell migration and invasion as well as in vivo tumor formation and metastasis. These findings will provide an increased understanding of the role of race-related alternative splicing in PCa disparities and potentially a new target for development of precision medicine interventions.

Citation Format: Tyler A. Allen, Jay Chandar, Bonnie L. Lacroix, Steven R. Patierno, Daniel J. George, Jennifer A. Freedman. Interrogating the role of race-related alternative splicing of SEMA3C in prostate cancer [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-128.

Abstract PO-100: Ancestry-related variation in Sphingosine Kinase Type 1-Interacting Protein (SKIP) and Sphingosine Kinase 1 (SPHK1) and response to secondary hormonal therapy in metastatic castration-resistant prostate cancer

The number of cases and deaths from prostate cancer (PCa) is highest for African American (AA) men compared with men of other racial and ethnic groups, and AA men more frequently have more aggressive disease. However, recent studies have shown that AA PCa patients have a better response to certain therapeutic regimens than white PCa patients. We conducted a DoD Prostate Cancer Clinical Trials Consortium (PCCTC) prospective study of secondary hormonal therapy (HT) in metastatic castration-resistant PCa (mCRPC) patients stratified by race, Abi-Race.

This study enrolled 50 AA and 50 white patients with mCRPC and received abiraterone and prednisone daily until disease progression or adverse event. AA men had higher rates of Prostate Specific Antigen (PSA) response and time to PSA progression. Herein we focus on correlative science in the context of Abi-Race to determine novel relationships between ancestry-related genetic variation and response and time to progression on secondary HT in mCRPC. An exploratory genome-wide analysis assessing the role of genotypic and local ancestry variation with respect to time to progression identified a missense variant in Sphingosine Kinase Type 1-Interacting Protein (SKIP) with predicted pathogenicity and potentially high ancestral variation. SKIP plays a role in modulating the conversion of sphingosine to sphingosine-1-phosphate (S1P) by regulating Sphingosine Kinase 1 (SPHK1) activity within the cytosol. S1P is a potent lipid mediator that plays a role in multiple cancer-promoting biofunctions. SKIP directly binds and inhibits SPHK1 activity, resulting in the decreased production of S1P and S1P-associated cell signaling. The relationship between SKIP and SPHK1 and response to secondary HT in mCRPC was investigated. We knocked down SKIP or SPHK1 in LN95 prostate cancer cells and assessed resulting alterations in proliferation with or without abiraterone. Knockdown of SKIP increased proliferation in untreated cells and knockdown cells were more resistant to treatment with abiraterone compared with the control group. Conversely, knockdown of SPHK1 decreased proliferation in untreated cells and knockdown cells were more sensitive to treatment with abiraterone compared with the control group. In addition, we are measuring changes in sphingosine and S1P in serum samples we collected from fasting Abi-Race patients at baseline and cycle 4 of treatment to investigate ancestry-related sphingosine and S1P variations and associated outcomes. Lastly, we are further investigating the potential function of the variant in SKIP associated with time to progression on secondary HT in mCRPC.

These findings will further the understanding of ancestry-related biological factors that influence response to secondary HT in mCRPC and could have direct implications for the timing and selection of AA patients for secondary HT and those needing additional therapy. Ultimately, such strategies have the potential to mitigate prostate cancer disparities.

Citation Format: Sean A. Piwarski, Tyler A. Allen, Dadong Zhang, Alexander B. Sibley, Patrick Healy, Brendon M. Patierno, Bonnie L. LaCroix, Rick A. Kittles, Kouros Owzar, Terry Hyslop, Steven R. Patierno, Daniel J. George, Jennifer A. Freedman. Ancestry-related variation in Sphingosine Kinase Type 1-Interacting Protein (SKIP) and Sphingosine Kinase 1 (SPHK1) and response to secondary hormonal therapy in metastatic castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-100.

Abstract B064: Race-related genetic variation and response to secondary hormonal therapy in metastatic castration-resistant prostate cancer

Prostate cancer (PCa) is the most prevalent cancer and third leading cause of cancer death among men in the United States. PCa incidence, aggressiveness and mortality are significantly higher among African Americans (AAs) compared with men of other racial groups. Despite the worse prognosis associated with African ancestry, several recent studies have shown that PCa patients of African ancestry have a better response to certain PCa therapeutic regimens than those of European ancestry. The overall objective of our study is to identify ancestry-related genetic variation that associates with outcomes on abiraterone/prednisone therapy in metastatic castration-resistant prostate cancer (mCRPC). Our central hypothesis is that differences in ancestry-related single nucleotide polymorphisms (SNPs), gene expression and/or metabolites will associate with prostate-specific antigen (PSA) response and time to progression on secondary hormonal therapy in mCRPC patients. Toward our objective, we collected whole blood, archival tumor tissue and serum from 50 self-identified AA and 50 self-identified white patients enrolled in the Abi Race study, a Phase II study of abiraterone/prednisone in AA and white men with mCRPC. To perform ancestral and genome-wide genotyping, we isolated DNA from the whole blood samples collected at baseline and interrogated DNA using the Infinium Multi-Ethnic Global BeadChip (Illumina). Preliminary analysis identified 622 SNPs that associated with PSA progression-free survival on abiraterone or variation in minor allele frequency by ancestry. To perform gene expression profiling, we isolated RNA from archival formalin-fixed, paraffin-embedded PCa tissue and interrogated RNA using a NanoString Custom CodeSet (NanoString Technologies). Preliminary analysis revealed significant race-related differential expression of 30 prostate cancer-related genes. To perform metabolomic profiling, we used fasting serum samples collected at baseline and during treatment and the Biocrates p400 HR Kit (Biocrates Life Sciences AG). From this analysis, we have prioritized four ancestry-related metabolites associated with time to confirmed PSA progression for further study. Future analyses will focus on defining the functional significance of the aforementioned ancestry-related genetic variation using preclinical cancer models and validation of the aforementioned ancestry-related genetic variation in an independent cohort. These findings will further understanding of ancestry-related biological factors that influence response to secondary hormonal therapy in mCRPC and could have direct implications for the timing and selection of AA patients for secondary hormonal therapy and those needing additional therapy. As secondary hormonal therapy use expands to earlier disease settings, these findings could support the need for further studies in AA men in these disease settings. Ultimately, such strategies have the potential to mitigate PCa disparity.

Citation Format: Tyler A Allen, Gary Lipton, Alexander B Sibley, Patrick Healy, Brendon M Patierno, Bonnie Lacroix, Steven R Patierno, Kouros Owzar, Terry Hyslop, Daniel J George, Jennifer A Freedman. Race-related genetic variation and response to secondary hormonal therapy in metastatic castration-resistant prostate cancer [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B064.

Circulating tumor cells exit circulation while maintaining multicellularity, augmenting metastatic potential

Metastasis accounts for the majority of all cancer deaths, yet the process remains poorly understood. A pivotal step in the metastasis process is the exiting of tumor cells from the circulation, a process known as extravasation. However, it is unclear how tumor cells extravasate and whether multicellular clusters of tumor cells possess the ability to exit as a whole or must first disassociate. In this study, we use in vivo zebrafish and mouse models to elucidate the mechanism tumor cells use to extravasate. We found that circulating tumor cells exit the circulation using the recently identified extravasation mechanism, angiopellosis, and do so as both clusters and individual cells. We further show that when melanoma and cervical cancer cells utilize this extravasation method to exit as clusters, they exhibit an increased ability to form tumors at distant sites through the expression of unique genetic profiles. Collectively, we present a new model for tumor cell extravasation of both individual and multicellular circulating tumor cells.This article has an associated First Person interview with the first author of the paper.

Platelet-Inspired Nanocells for Targeted Heart Repair After Ischemia/Reperfusion Injury

Cardiovascular disease is the leading cause of mortality worldwide. While reperfusion therapy is vital for patient survival post-heart attack, it also causes further tissue injury, known as myocardial ischemia/reperfusion (I/R) injury in clinical practice. Exploring ways to attenuate I/R injury is of clinical interest for improving post-ischemic recovery. A platelet-inspired nanocell (PINC) that incorporates both prostaglandin E2 (PGE2)-modified platelet membrane and cardiac stromal cell-secreted factors to target the heart after I/R injury is introduced. By taking advantage of the natural infarct-homing ability of platelet membrane and the overexpression of PGE2 receptors (EPs) in the pathological cardiac microenvironment after I/R injury, the PINCs can achieve targeted delivery of therapeutic payload to the injured heart. Furthermore, a synergistic treatment efficacy can be achieved by PINC, which combines the paracrine mechanism of cell therapy with the PGE2/EP receptor signaling that is involved in the repair and regeneration of multiple tissues. In a mouse model of myocardial I/R injury, intravenous injection of PINCs results in augmented cardiac function and mitigated heart remodeling, which is accompanied by the increase in cycling cardiomyocytes, activation of endogenous stem/progenitor cells, and promotion of angiogenesis. This approach represents a promising therapeutic delivery platform for treating I/R injury.

Cardiac Stem Cell Patch Integrated with Microengineered Blood Vessels Promotes Cardiomyocyte Proliferation and Neovascularization after Acute Myocardial Infarction

Cardiac stem cell (CSC) therapy has shown preclinical and clinical evidence for ischemic heart repair but is limited by low cellular engraftment and survival after transplantation. Previous versions of the cardiac patch strategy improve stem cell engraftment and encourage repair of cardiac tissue. However, cardiac patches that can enhance cardiomyogenesis and angiogenesis at the injured site remain elusive. Therapies that target cardiomyocyte proliferation and new blood vessel formation hold great potential for the protection against acute myocardial infarction (MI). Here, we report a new strategy for creating a vascularized cardiac patch in a facile and modular fashion by leveraging microfluidic hydrodynamic focusing to construct the biomimetic microvessels (BMVs) that include human umbilical vein endothelial cells (HUVECs) lining the luminal surface and then encapsulating the BMVs in a fibrin gel spiked with human CSCs. We show that the endothelialized BMVs mimicked the natural architecture and function of capillaries and that the resultant vascularized cardiac patch (BMV-CSC patch) exhibited equivalent release of paracrine factors compared to those of coculture of genuine human CSCs and HUVECs after 7 days of in vitro culture. In a rat model of acute MI, the BMV-CSC patch therapy induced profound mitotic activities of cardiomyocytes in the peri-infarct region 4 weeks post-treatment. A significant increase in myocardial capillary density was noted in the infarcted hearts that received BMV-CSC patch treatment compared to the infarcted hearts treated with conventional CSC patches. The striking therapeutic benefits and the fast and facile fabrication of the BMV-CSC patch make it promising for practical applications. Our findings suggest that the BMV-CSC patch strategy may open up new possibilities for the treatment of ischemic heart injury.

Safety and Efficacy of Allogeneic Lung Spheroid Cells in a Mismatched Rat Model of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a devastating interstitial lung disease characterized by the relentless deposition of extracellular matrix causing lung distortions and dysfunctions. The prognosis after detection is merely 3-5 years and the only two Food and Drug Administration-approved drugs treat the symptoms, not the disease, and have numerous side effects. Stem cell therapy is a promising treatment strategy for pulmonary fibrosis. Current animal and clinical studies focus on the use of adipose or bone marrow-derived mesenchymal stem cells. We, instead, have established adult lung spheroid cells (LSCs) as an intrinsic source of therapeutic lung stem cells. In the present study, we compared the efficacy and safety of syngeneic and allogeneic LSCs in immuno-competent rats with bleomycin-induced pulmonary inflammation in an effort to mitigate fibrosis development. We found that infusion of allogeneic LSCs reduces the progression of inflammation and fibrotic manifestation and preserves epithelial and endothelial health without eliciting significant immune rejection. Our study sheds light on potential future developments of LSCs as an allogeneic cell therapy for humans with pulmonary fibrosis. Stem Cells Translational Medicine 2017;9:1905-1916.

Derivation of therapeutic lung spheroid cells from minimally invasive transbronchial pulmonary biopsies

Background

Resident stem and progenitor cells have been identified in the lung over the last decade, but isolation and culture of these cells remains a challenge. Thus, although these lung stem and progenitor cells provide an ideal source for stem-cell based therapy, mesenchymal stem cells (MSCs) remain the most popular cell therapy product for the treatment of lung diseases. Surgical lung biopsies can be the tissue source but such procedures carry a high risk of mortality.

Methods

In this study we demonstrate that therapeutic lung cells, termed “lung spheroid cells” (LSCs) can be generated from minimally invasive transbronchial lung biopsies using a three-dimensional culture technique. The cells were then characterized by flow cytometry and immunohistochemistry. Angiogenic potential was tested by in-vitro HUVEC tube formation assay. In-vivo bio- distribution of LSCs was examined in athymic nude mice after intravenous delivery.

Results

From one lung biopsy, we are able to derive >50 million LSC cells at Passage 2. These cells were characterized by flow cytometry and immunohistochemistry and were shown to represent a mixture of lung stem cells and supporting cells. When introduced systemically into nude mice, LSCs were retained primarily in the lungs for up to 21 days.

Conclusion

Here, for the first time, we demonstrated that direct culture and expansion of human lung progenitor cells from pulmonary tissues, acquired through a minimally invasive biopsy, is possible and straightforward with a three-dimensional culture technique. These cells could be utilized in long-term expansion of lung progenitor cells and as part of the development of cell-based therapies for the treatment of lung diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF).

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0611-0) contains supplementary material, which is available to authorized users.

A Regenerative Cardiac Patch Formed by Spray Painting of Biomaterials onto the Heart

Layering a regenerative polymer scaffold on the surface of the heart, termed as a cardiac patch, has been proven to be effective in preserving cardiac function after myocardial infarction (MI). However, the placement of such a patch on the heart usually needs open-chest surgery, which is traumatic, therefore prevents the translation of this strategy into the clinic. We sought to device a way to apply a cardiac patch by spray painting in situ polymerizable biomaterials onto the heart with a minimally invasive procedure. To prove the concept, we used platelet fibrin gel as the "paint" material in a mouse model of MI. The use of the spraying system allowed for placement of a uniform cardiac patch on the heart in a mini-invasive manner without the need for sutures or glue. The spray treatment promoted cardiac repair and attenuated cardiac dysfunction after MI.

Angiopellosis as an Alternative Mechanism of Cell Extravasation

Stem cells possess the ability to home in and travel to damaged tissue when injected intravenously. For the cells to exert their therapeutic effect, they must cross the blood vessel wall and enter the surrounding tissues. The mechanism of extravasation injected stem cells employ for exit has yet to be characterized. Using intravital microscopy and a transgenic zebrafish line Tg(fli1a:egpf) with GFP-expressing vasculature, we documented the detailed extravasation processes in vivo for injected stem cells in comparison to white blood cells (WBCs). While WBCs left the blood vessels by the standard diapedesis process, injected cardiac and mesenchymal stem cells underwent a distinct method of extravasation that was markedly different from diapedesis. Here, the vascular wall undergoes an extensive remodeling to allow the cell to exit the lumen, while the injected cell remains distinctively passive in activity. We termed this process Angio-pello-sis, which represents an alternative mechanism of cell extravasation to the prevailing theory of diapedesis. Stem Cells 2017;35:170-180 Video Highlight: https://youtu.be/i5EI-ZvhBps.

Rapid and Efficient Production of Coronary Artery Ligation and Myocardial Infarction in Mice Using Surgical Clips

Aims

The coronary artery ligation model in rodents mimics human myocardial infarction (MI). Normally mechanical ventilation and prolonged anesthesia period are needed. Recently, a method has been developed to create MI by popping-out the heart (without ventilation) followed by immediate suture ligation. Mortality is high due to the time-consuming suture ligation process while the heart is exposed. We sought to improve this method and reduce mortality by rapid coronary ligation using a surgical clip instead of a suture.

Methods and Results

Mice were randomized into 3 groups: clip MI (CMI), suture MI (SMI), or sham (SHAM). In all groups, heart was manually exposed without intubation through a small incision on the chest wall. Unlike the conventional SMI method, mice in the CMI group received a metal clip on left anterior descending artery (LAD), quickly dispensed by an AutoSuture Surgiclip^™. The CMI method took only 1/3 of ligation time of the standard SMI method and improved post-MI survival rate. TTC staining and Masson’s trichrome staining revealed a similar degree of infarct size in the SMI and CMI groups. Echocardiograph confirmed that both SMI and CMI groups had a similar reduction of ejection fraction and fraction shortening over the time. Histological analysis showed that the numbers of CD68⁺ macrophages and apoptotic cells (TUNEL-positive) are indistinguishable between the two groups.

Conclusion

This new method, taking only less than 3 minutes to complete, represents an efficient myocardial infarction model in rodents.

Species-specific injury-induced cell proliferation in the hippocampus and subventricular zone of food-storing and nonstoring wild birds

Cells are continuously born and incorporated into the adult hippocampus (HP). Adult neurogenesis might act to increase the total number of cells or replace dead cells. Thus, neurogenesis might be a primary factor in augmenting, maintaining, or even recovering functions. In zebra finches, HP injury increases cell proliferation in the HP and stem cell rich subventricular zone (SVZ). It is unknown what effect injury has on a species dependent upon the HP for survival in the wild. In food-storing birds, recovery of caches is seasonal, necessary for survival, dependent upon the HP and is concomitant with a peak in HP neurogenesis. During the fall, food-storing black-capped chickadees (BCCs) and nonstoring dark-eyed juncos (DEJs) were captured and given a unilateral penetrating lesion to the HP one day later. On day 3, birds were injected with the mitotic marker 5-bromo-2'-deoxyuridine (BrdU) and perfused on day 10. If unlesioned, more BrdU-labeled cells were observed in the HP and SVZ of BCCs compared to DEJs, indicating higher innate cell proliferation or incorporation in BCCs. If lesioned, BrdU-labeled cells increased in the injured HP of both species; however, lesions caused larger increases in DEJs. DEJs also showed increases in BrdU-labeled cells in the SVZ and contralateral HP. BCCs showed no such increases on day 10. Thus, during the fall food-storing season, storers showed suppressed injury-induced cell proliferation and/or reduced survival rates of these new cells compared to nonstorers. These species differences may provide a useful model for isolating factors involved in cellular responses following injury.

Effects of hydrochlorothiazide and diet in dogs with calcium oxalate urolithiasis

OBJECTIVE

To determine whether hydrochlorothiazide (HCTZ) reduces urinary calcium excretion in dogs with calcium oxalate urolithiasis.

DESIGN

Original study.

ANIMALS

8 dogs with calcium oxalate urolithiasis.

PROCEDURE

4 treatment protocols were evaluated in each dog (a low calcium, low protein diet designed to prevent calcium oxalate urolith formation with and without administration of HCTZ [2 mg/kg (0.9 mg/lb) of body weight, PO, q 12 h] and a maintenance diet with higher quantities of protein and calcium with and without administration of HCTZ). At the end of each 2-week treatment period, 24-hour urine samples were collected. Blood samples were collected during the midpoint of each urine collection period. Analysis of variance was performed to evaluate the effects of HCTZ and diet on urine and serum analytes.

RESULTS

Hydrochlorothiazide significantly decreased urine calcium and potassium concentration and excretion. Hydrochlorothiazide also significantly decreased serum potassium concentration. Compared with the maintenance diet, the urolith prevention diet significantly decreased urine calcium and oxalic acid concentration and excretion. Dogs consuming the urolith prevention diet had significantly lower serum concentrations of albumin and urea nitrogen.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of HCTZ decreased urine calcium excretion in dogs with a history of calcium oxalate urolith formation. The greatest reduction in urine calcium concentration and excretion was achieved when dogs received HCTZ and the urolith prevention diet. Results of this study suggest that the hypocalciuric effect of HCTZ will minimize recurrence of calcium oxalate urolith formation in dogs; however, long-term controlled clinical trials are needed to confirm the safety and effectiveness of HCTZ.

Patient and environmental factors associated with calcium oxalate urolithiasis in dogs

OBJECTIVE

To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs.

DESIGN

Case-control study.

ANIMALS

1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths.

PROCEDURE

A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation.

RESULTS

Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk.

CONCLUSIONS AND CLINICAL RELEVANCE

Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence.

Medical dissolution and prevention of canine struvite urolithiasis. Twenty years of experience

Two types of canine struvite uroliths have been recognized: infection-induced struvite is the most common type; sterile struvite is uncommonly recognized. Infection-induced struvite is most commonly associated with urease-producing staphylococcal UTI. For dogs that qualify, medical dissolution is an effective method of treatment. Medical dissolution protocols encompass: (1) eradication or control of UTI; (2) use of calculolytic diets; and (3) administration of urease inhibitors to patients with persistent UTI caused by urease-producing microbes.

Methods for evaluating treatment of uroliths

Formation of uroliths is not a disease but rather a complication of several disorders. Some disorders can be identified and corrected (e.g., infection-induced struvite urolith formation), and some can be identified but not corrected (e.g., hyperuricosuria occurring in Dalmatians that form ammonium urate uroliths), although for others, the underlying etiopathogenesis is not known (e.g., calcium oxalate urolith formation in Miniature Schnauzers). A common denominator of these disorders is that from time to time, they can create oversaturation of urine with one or more crystal precursors, resulting in formation of crystals. To develop rational and effective approaches to treatment, abnormalities that promote urolith formation must be identified with the goal of eliminating or modifying them. It is therefore important to understand several basic concepts associated with urolithiasis.

Canine calcium oxalate urolithiasis. Case-based applications of therapeutic principles

The case study presented here illustrates the diagnosis and management of calcium oxalate urolithiasis in a Bichon Frise, a breed at increased risk for this type of stone. If the Bichon Frise had persistent hypercalcemia, we would have evaluated serum concentrations of ionized calcium, parathyroid hormone, and vitamin D to identify an underlying cause. Because his urine was alkaline, additional potassium citrate was not provided. Likewise, as a fortified diet was fed to him, vitamin B6 therapy was not considered. This case study illustrates the benefits of radiographic evaluation immediately following surgery and during follow-up examinations. If we had postponed radiographs until the patient developed clinical signs, additional surgical procedures may have been required.

Measurement of the influence of diet on feline urinary pH

The kidneys eliminate the acid produced each day by metabolism and diet. Consequently, urinary pH is influenced by diet. The urinary pH of cats consuming a natural habitual diet consisting of small mammal carcasses is between 6.2 and 6.4. Although the only authoritative way to determine the effect of diet on urinary pH is a feeding trial, there is no universally accepted protocol for measuring urinary pH. When interpreting the urinary pH of a spot or random sample, it is necessary to consider when the sample was obtained relative to time of eating.

Estimation of quantitative enzymuria in dogs with gentamicin-induced nephrotoxicosis using urine enzyme/creatinine ratios from spot urine samples

The correlation between 24-hour urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyl transferase (GGT) with urine NAG and GGT/creatinine ratios was assessed in dogs with gentamicin-induced nephrotoxicosis. Eighteen 6-month-old male Beagles with normal renal function were randomly divided into 3 groups of 6. Each group was fed a different concentration of protein (high protein, 27.3%; medium protein, 13.7%; and low protein, 9.4%) for 21 days. After dietary conditioning, gentamicin was administered at a dose of 10 mg/kg IM tid for 8 days and each group was continued on its respective diet. Endogenous creatinine clearance and 24-hour urinary excretion of NAG and GGT were determined after dietary conditioning (day 0) and on days 2, 4, 6, and 8 of gentamicin administration. In addition, urine NAG and GGT/creatinine ratios (IU/L divided by mg/dL) were determined from catheterized spot urine samples obtained between 7 and 10 AM on the same days. The correlation between 24-hour urinary enzyme excretion and urine enzyme/creatinine ratio in the spot urine samples was evaluated by simple linear regression analysis. Spot sample urine enzyme/creatinine ratios were significantly correlated with 24-hour urinary enzyme excretion through day 4 for dogs on low dietary protein, through day 6 for those on medium protein, and through day 8 for those on high dietary protein. Mean +/- SD baseline values for urine NAG/creatinine ratio and 24-hour urinary NAG excretion were 0.06 +/- 0.04 and 0.19 +/- 0.14 IU/kg/24 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of two amounts of dietary casein on uric acid, sodium urate, and ammonium urate urinary activity product ratios of healthy beagles

Casein has been used as a protein source in diets designed to dissolve canine ammonium urate uroliths and to prevent their recurrence, because it contains fewer purine precursors than do many other sources of protein. However, an important question is whether reduced quantities of dietary casein have any benefit in modifying saturation of urine with urates. To answer this question, activity product ratios of uric acid, sodium urate, and ammonium urate were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of a 10.4% protein, casein-based (10.4% casein) diet and a 20.8% protein, casein-based (20.8%casein) diet. Significantly lower 24-hour urinary excretions of ammonia and phosphorus were observed when dogs consumed the 10.4% casein diet. These results suggest that use of the 10.4% casein diet in protocols designed for dissolution and prevention of uric acid, sodium urate, and ammonium urate uroliths in dogs may be beneficial.

Diet effect on activity product ratios of uric acid, sodium urate, and ammonium urate in urine formed by healthy beagles

Urine activity product ratios of uric acid, sodium urate, and ammonium urate and urinary excretion of metabolites were determined in 24-hour samples produced by 6 healthy Beagles during periods of consumption of a low-protein, casein-based diet (diet A) and a high-protein, meat-based diet (diet B). Comparison of effects of diet A with those of diet B revealed: significantly lower activity product ratios of uric acid (P = 0.025), sodium urate (P = 0.045), and ammonium urate (P = 0.0045); significantly lower 24-hour urinary excretion of uric acid (P = 0.002), ammonia (P = 0.0002), sodium (P = 0.01), calcium (P = 0.005), phosphorus (P = 0.0003), magnesium (P = 0.01), and oxalic acid (P = 0.004); significantly (P = 0.0001) higher 24-hour urine pH; and significantly (P = 0.01) lower endogenous creatinine clearance. These results suggest that consumption of diet A minimizes changes in urine that predispose dogs to uric acid, sodium urate, and ammonium urate urolithiasis.

Influence of four diets containing approximately 11% protein (dry weight) on uric acid, sodium urate, and ammonium urate urine activity product ratios of healthy beagles

Urine activity product ratios of uric acid (APRua), sodium urate (APRna), and ammonium urate (APRau), and urinary excretion of 10 metabolites were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of consumption of 4 diets containing approximately 11% protein (dry weight) and various protein sources: a 72% moisture, casein-based diet; a 10% moisture, egg-based diet; a 72% moisture, chicken-based diet; and a 71% moisture, chicken-based, liver-flavored diet. Significantly (P < 0.05) higher APRua, APRna, and APRau were observed when dogs consumed the egg-based diet, compared with the other 3 diets; there were no differences in these ratios among the other 3 diets. Twenty-four-hour urinary excretions of chloride, potassium, phosphorus, and oxalic acid were significantly (P < 0.05) higher when dogs consumed the egg-based diet. Twenty-four-hour urinary excretions of sodium were significantly (P < 0.05) higher when dogs consumed the egg-based diet, compared with the casein-based diet and the chicken-based, liver-flavored diet, but were not significantly different between the egg-based diet and chicken-based diet. Twenty-four-hour urine volume was similar when dogs consumed the 4 diets. Twenty-four-hour endogenous creatinine clearance was significantly (P < 0.05) lower when dogs consumed the casein-based diet; there were no differences among the other 3 diets. Although consumption of all diets was associated with production of alkaline urine, the 24-hour urine pH was significantly (P < 0.05) higher when dogs consumed the egg-based diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal diagnosis of moderate unilateral hydrocephalus subsequently not requiring neonatal decompression

Prenatal diagnosis of unilateral hydrocephalus is unusual. In the past most such cases have been treated with neonatal shunting procedures. We present an unusual case in which moderate unilateral hydrocephalus was diagnosed prenatally at 30 weeks' gestation. Despite prenatal and neonatal sonographic signs of both cortical thinning and mild displacement of midline intracranial structures, confirmed by computed tomography, neonatal shunting was not required. The findings and course in this unusual case suggest that infrequently some of the milder cases of idiopathic nonprogressive unilateral hydrocephalus discovered later in life may possibly represent late detection of this preexisting condition.

The effect of combined therapy with captopril, furosemide, and a sodium-restricted diet on serum electrolyte concentrations and renal function in normal dogs and dogs with congestive heart failure

Captopril, furosemide, and a sodium-restricted diet were administered to 6 normal dogs and 10 dogs with congestive heart failure. Serum electrolyte concentrations and renal function were monitored in both groups. In the normal dogs, no clinically meaningful changes in serum electrolyte, urea nitrogen, or creatinine concentrations developed during therapy with a sodium-restricted diet and 4 weeks each of furosemide alone, captopril alone, or furosemide plus captopril. Three of 6 normal dogs on furosemide and a sodium-restricted diet had at least one serum potassium concentration above the reference range during the 4 weeks of observation. One normal dog on captopril, furosemide, and a sodium-restricted diet developed azotemia, and 2 dogs had serum potassium concentrations above the reference range during the 4 weeks of observation. Ten dogs with congestive heart failure were treated with captopril, furosemide, a sodium-restricted diet, and digoxin. Etiopathogenesis of the heart failure included valvular insufficiency (n = 6), dilated cardiomyopathy (n = 3), and dilated cardiomyopathy and dirofilariasis (n = 1). Serum electrolyte concentrations and renal function were monitored for 5 consecutive weeks in 7 of the 10 dogs and for 17 weeks or longer in 6. Two dogs were euthanized after 4 weeks because of acute decompensation of heart failure, and one dog developed severe azotemia and uremia. Six of 10 dogs with congestive heart failure had at least one serum potassium concentration above the reference range sometime during the 5 weeks of observation, although the changes in the mean serum potassium concentrations were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary protein conditioning on gentamicin pharmacokinetics in dogs

Eighteen, six-month-old male Beagles with normal renal function were randomly divided into three groups of 6. Each group was fed a diet that was similar except for protein content (high = 26%, medium = 13% and low = 9%, all on an as fed basis) throughout the experimental period. After a 21 day dietary protein conditioning period (including a terminal 2 day testing period), gentamicin was administered at a dosage of 10 mg/kg q. 8 h for 8 days. The first dose on days 1 and 7 was administered i.v. and all others were given i.m. Pharmacokinetic parameters were determined using blood samples collected over an 8 h period following the i.v. dose on day 1. The elimination rate constant was calculated on days 1 and 7. The data best fit a two-compartment open model for all dogs on day 1. The volume of distribution was higher and the clearance greater in the high protein group compared to the other two groups. No difference was found in the rate of elimination between days 1 and 7 for the high protein group; however, in the medium and low protein groups the rate of elimination decreased over the 7 days of treatment. Therefore, high dietary protein prior to and during gentamicin administration induced faster gentamicin clearance and a larger volume of distribution and preserved the ability to eliminate gentamicin in dogs with normal renal function.

Fetal scapular length in the ultrasonographic assessment of gestational age

A prospective cross-sectional study of 515 singleton fetuses of ages between 15 and 42 weeks' gestation was performed. At gestational ages greater than 26 weeks, only fetuses with a sonographic estimated fetal weight between the 10th and 90th percentiles for growth were included. Scapular length (cm) as a function of gestational age (weeks) was expressed by the regression equation: SL = 0.3289 + 0.9553 (GA) with a Pearson correlation coefficient of R2 = 0.942. This study defines the normal limits of scapular length, demonstrates a high correlation between scapular length, gestational age, and other standard measurements of fetal growth, and indicates that scapular length can predict gestational age in fetuses with normal growth.

Prenatal sonographic diagnosis of non-rhizomelic chondrodysplasia punctata

BACKGROUND

Chondrodysplasia punctata is a rare heterogeneous group of bone dysplasias occurring with an incidence of one in 100,000 live births. Prenatal sonographic diagnosis of non-rhizomelic chondrodysplasia punctata (Conradi-Hünermann syndrome) has previously been reported only following detection of overall limb shortening.

CASE

Multiple sonographic skeletal findings of premature epiphyseal calcifications, other unusual calcifications, kyphoscoliosis, and asymmetrical limb shortening, typical of non-rhizomelic chondrodysplasia punctata, led to second-trimester prenatal sonographic diagnosis of this condition.

CONCLUSION

Second-trimester prenatal sonographic diagnosis of premature epiphyseal calcifications associated with non-rhizomelic chondrodysplasia punctata is possible.

Effects of dietary protein conditioning on gentamicin-induced nephrotoxicosis in healthy male dogs

Eighteen 6-month-old male Beagles with normal renal function were allotted at random to 3 groups of 6 dogs each. For 21 days, each group was fed a diet that was similar except for protein content (high protein, 27.3%; medium protein, 13.7%; and low protein, 9.4%). After the conditioning period, gentamicin was administered at a dosage of 10 mg/kg of body weight, IM, every 8 hours for 8 days, and the respective diet was continued. Clearance of endogenous creatinine, 24-hour urinary excretion of protein and enzymes (gamma-glutamyltransferase, and N-acetyl-beta-D-glucosaminidase, and fractional clearance of sodium and potassium (%) were determined before and after dietary protein conditioning and on days 2, 4, 6, and 8 of gentamicin administration. Additionally, trough serum gentamicin concentration was determined on days 2, 4, 6, and 8 of gentamicin administration. At the end of the study, all dogs were euthanatized; renal histologic features were graded, using a continuous ranking scale, and renal cortical gentamicin concentrations were measured. Data were ranked and analyzed, using a nonparametric equivalent of a two-way ANOVA; P < 0.05 was considered significant. After the dietary conditioning period (prior to gentamicin), dogs fed the high-protein diet had higher endogenous creatinine clearance and urinary excretion of protein, compared with dogs fed the low-protein diet. Differences existed among groups after 8 days of gentamicin administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of renal biopsy techniques in dogs

To evaluate adequacy of biopsy specimens obtained and safety to the patient, the standard keyhole biopsy technique (using digital immobilization of the right kidney and placement of the biopsy needle up to the capsule before obtaining a tissue sample) was compared with 9 technical modifications. Adequacy was judged by the number of intact glomeruli observed in the specimen. Detection of transected blood vessels and renal pelvis was presumed to have predictive value for postbiopsy complications of hemorrhage and hydronephrosis. Needle biopsy specimens were also obtained from left and right kidneys by use of laparoscopic visualization and were compared with those obtained by use of the standard keyhole technique. Although the standard keyhole technique yielded the highest percentage of adequate biopsy specimens, there was no statistical difference between specimens obtained by this technique and those obtained by the modified technique or by laparoscope-guided biopsy. Also, significant difference in percentage of biopsy specimens with renal pelvis was not found between specimens obtained by the standard and modified techniques. For each technique, the biopsy core length was measured and the mean value was calculated. In this study, core length did not correlate with adequacy of the biopsy specimen.

Obesity: occurrence, treatment, and prevention

Obesity is the most common nutritionally related disease of dogs and cats. Several of the important health problems that are inherent with obesity are resolved when the patient's body weight is returned to normal. Proper dietary management is central to successful treatment and prevention. Low-fat, high-fiber diets provide fewer available calories but induce a greater degree of satiety than simple restriction of the obese patient's regular food. Care must be taken to assure that overweight cats are not fasted, because preliminary reports indicate an alarming association between severe caloric restriction and hepatic lipidosis in obese cats. Obesity prevention should ideally be proactive, owing to the predictability of obesity in certain groups of pets. The large number of reduced-energy maintenance type diets that are available for obesity prevention facilitate this goal.

Bilateral hydronephrosis attributable to bilateral ureteral fibrosis in a cat

A 4-year-old castrated male Burmese cat was evaluated because of nonregenerative anemia (PCV, 20%) and was found to have renal failure. Renal ultrasonography revealed bilateral hydronephrosis. Antegrade pyelography of the right kidney failed to indicate obstructive disease. Necropsy and histologic examination of the ureters revealed a markedly stenotic lumen and massive fibrosis of the mucosa. An etiologic agent could not be found.

Hyperammonemia associated with urethral obstruction in a dog

Hyperammonemia was documented in a 10-week-old male Lhasa Apso referred for urethral obstruction and rupture. Results of liver function tests were normal. Staphylococcus sp was isolated from urine. Anomalies of the portal vascular system and hepatic insufficiency are the most common causes of hyperammonemia in the dog. Hyperammonemia, however, in the absence of recognizable concurrent hepatic disease, also may result from urinary stasis and infection with urea-splitting organisms.

Hypodipsic hypernatremia and associated myopathy in a hydrocephalic cat with transient hypopituitarism

Hypodipsic hypernatremia developed in association with hypopituitarism and hydrocephalus in a 7-month-old cat. Initial clinical signs (generalized weakness, cervical ventroflexion) were related to a hypernatremia-induced polymyopathy. Forced water intake and dietary sodium restriction corrected the hypernatremia and signs of muscle dysfunction. After restoration of eunatremia, secretion of pituitary hormones normalized. It was speculated that hypothalamic dysfunction, possibly related to hydrocephalus, induced both hypodipsia and transient hypopituitarism.

Microbiologic evaluation of canine urine: direct microscopic examination and preservation of specimen quality for culture

Urine specimens were obtained from 115 dogs. Each specimen was divided into 2 aliquots; one aliquot was placed into a sterile container (non-preserved), and the other was preserved in a boric acid-glycerol-sodium formate at 4 C. Both aliquots were then transported to a laboratory, and specimens of each aliquot were bacteriologically cultured immediately upon arrival at the laboratory. Specimens of the preserved aliquot also were cultured after 24, 48, and 72 hours of preservation. In 47 specimens containing greater than or equal to 1 X 10(4) colony-forming units (CFU)/ml, the results of quantitative bacteriologic culturing of preserved urine at 0, 24, 48, and 72 hours were the same as the result of the immediate quantitative bacteriologic culture of non-preserved urine. In 2 of 5 specimens containing greater than or equal to 1 X 10(3) CFU/ml but less than 1 X 10(4) CFU/ml, the results of quantitative bacteriologic culture of preserved urine differed from the corresponding immediate culture of nonpreserved urine. Bacteria were not isolated from 63 specimens (less than 1 X 10(3) CFU/ml). Bacteriologic cultures of preserved urine were also negative for bacterial growth at 0, 24, 48, and 72 hours. Bacteriuria was detected by direct microscopic examination of gram-stained smears of uncentrifuged urine in 50 of 52 urine specimens from dogs with urinary tract infection. Bacteria were observed in 1 of 63 specimens that did not have bacterial growth when cultured.

Renal functional relationships in dogs with glomerulopathies

Glomerular filtration rate, effective renal plasma flow, and filtration fraction were determined by measuring plasma disappearance of [14C] inulin and [3H]tetraethylammonium bromide after a single IV bolus injection was given to 8 dogs with membranous nephropathy, renal glomerulosclerosis, or renal amyloidosis. Glomerular filtration rate was decreased in the 8 dogs. Effective renal plasma flow was within reference values in 1 dog, increased in 1 dog, and decreased in 6 dogs. Filtration fraction was within reference values in 2 dogs and decreased in 6 dogs. The glomerular filtration rate also was estimated by the endogenous creatinine clearance technique and was decreased in the 8 dogs with glomerulopathies.

A technique for estimating progression of chronic renal failure in the dog

A simple method for estimating the rate of progression of chronic renal failure was evaluated in 11 dogs. The plot of the reciprocal of the serum creatinine concentration vs age declined linearly, and projection of the regression line to the abscissa accurately predicted each dog's age at the time of death attributable to renal failure. The linear decline of the reciprocal of the serum creatinine concentration vs age indicated that nephrons may be lost at a constant rate in dogs with chronic renal failure. Changes in the slope of this line may provide a means of evaluating response to treatment.

Applicability of leukocyte esterase test strip in detection of canine pyuria

A commercially available leukocyte esterase assay was evaluated for application in analyzing canine urine for the detection of pyuria. In 229 urine samples, the leukocyte esterase activity was compared with leukocyte concentrations, as assessed by microscopic sediment analysis and chamber cell counts. The leukocyte esterase assay was specific (93.2%) for canine pyuria, but was poorly sensitive (46.0%) and did not appear to be applicable to analysis of canine urine samples.

Endocarditis caused by Corynebacterium sp in a dog

Mitral valve bacterial endocarditis, caused by Corynebacterium sp, was diagnosed in a dog. The bacteria had characteristics unlike those commonly recognized for most species of Corynebacterium. The primary source of bacteremia was suspected to be a pilonidal cyst of the sacrum. The dog was treated with a first-generation cephalosporin for 6 weeks, and the pilonidal cyst was surgically removed. Physical examination 1 year after initial examination revealed no abnormalities other than a cardiac murmur. On echocardiographic examination 1 year after treatment, the vegetative lesion was still present; however, chamber dimensions had returned to normal. Wall thickness and contractility remained increased.