Naturally occurring canine laminopathy leading to a dilated and fibrosing cardiomyopathy in the Nova Scotia Duck Tolling Retriever

Dilated cardiomyopathy (DCM) is characterized by decreased systolic function and dilation of one or both ventricles, often leading to heart failure or sudden death. Two 10-month-old sibling Nova Scotia Duck Tolling Retrievers (NSDTR) died acutely with evidence of dilated cardiomyopathy with myocardial fibrosis. Association analysis using two cases and 35 controls identified three candidate regions homozygous in the two cases. Whole genome sequencing identified a frameshift deletion in the LMNA gene (NC_049228.1:g.41688530del, NP_001274080:p.(Asp576ThrfsTer124)). Three retrospectively identified NSDTRs with sudden death before 2 years of age and severe myocardial fibrosis were also homozygous for the deletion. One 5 year old with sudden death and myocardial fibrosis was heterozygous for the deletion. This variant was not identified in 722 dogs of other breeds, nor was it identified to be homozygous in 784 NSDTR. LMNA codes for lamin A/C proteins, which are type V intermediate filaments that provide structural support to the nuclear membrane. In humans, LMNA variants can cause DCM with sudden death as well as diseases of striated muscles, lipodystrophy, neuropathies, and accelerated aging disorders. This frameshift deletion is predicted to affect processing of prelamin A into lamin A. Pedigree analysis in the NSDTR and functional evaluation of heterozygotes is consistent with a predominantly recessive mode of inheritance and possibly low penetrance in heterozygotes in contrast to people, where most pathogenic LMNA variants are dominantly inherited.

Advancing Treatments for Feline Hypertrophic Cardiomyopathy: The Role of Animal Models and Targeted Therapeutics

Feline HCM is the most common cardiovascular disease in cats, leading to devastating outcomes, including congestive heart failure (CHF), arterial thromboembolism (ATE), and sudden death. Evidence demonstrating long-term survival benefit with currently available therapies is lacking. Therefore, it is imperative to explore intricate genetic and molecular pathways that drive HCM pathophysiology to inspire the development of novel therapeutics. Several clinical trials exploring new drug therapies are currently underway, including those investigating small molecule inhibitors and rapamycin. This article outlines the key work performed using cellular and animal models that has led to and continues to guide the development of new innovative therapeutic strategies.

Delayed-release rapamycin halts progression of left ventricular hypertrophy in subclinical feline hypertrophic cardiomyopathy: results of the RAPACAT trial

OBJECTIVE

Feline hypertrophic cardiomyopathy (HCM) remains a disease with little therapeutic advancement. Rapamycin modulates the mTOR pathway, preventing and reversing cardiac hypertrophy in rodent disease models. Its use in human renal allograft patients is associated with reduced cardiac wall thickness. We sought to evaluate the effects of once-weekly delayed-release (DR) rapamycin over 6 months on echocardiographic, biochemical, and biomarker responses in cats with subclinical, nonobstructive HCM.

ANIMALS

43 client-owned cats with subclinical HCM.

METHODS

Cats enrolled in this double-blinded, multicentered, randomized, and placebo-controlled clinical trial were allocated to low- or high-dose DR rapamycin or placebo. Cats underwent physical examination, quality-of-life assessment, blood pressure, hematology, biochemistry, total T4, urinalysis, N-terminal pro-B-type natriuretic peptide, and cardiac troponin I at baseline and days 60, 120, and 180. Fructosamine was analyzed at screening and day 180. Echocardiograms were performed at all time points excluding day 120. Outcome variables were compared using a repeated measures ANCOVA.

RESULTS

No demographic, echocardiographic, or clinicopathologic values were significantly different between study groups at baseline, confirming successful randomization. At day 180, the primary study outcome variable, maximum LV myocardial wall thickness at any location, was significantly lower in the low-dose DR rapamycin group compared to placebo (P = .01). Oral DR rapamycin was well tolerated with no significant differences in adverse events between groups.

CLINICAL RELEVANCE

Results demonstrate that DR rapamycin was well tolerated and may prevent or delay progressive LV hypertrophy in cats with subclinical HCM. Additional studies are warranted to confirm and further characterize these results.

Multi-Omic, Histopathologic, and Clinicopathologic Effects of Once-Weekly Oral Rapamycin in a Naturally Occurring Feline Model of Hypertrophic Cardiomyopathy: A Pilot Study

Hypertrophic cardiomyopathy (HCM) remains the single most common cardiomyopathy in cats, with a staggering prevalence as high as 15%. To date, little to no direct therapeutical intervention for HCM exists for veterinary patients. A previous study aimed to evaluate the effects of delayed-release (DR) rapamycin dosing in a client-owned population of subclinical, non-obstructive, HCM-affected cats and reported that the drug was well tolerated and resulted in beneficial LV remodeling. However, the precise effects of rapamycin in the hypertrophied myocardium remain unknown. Using a feline research colony with naturally occurring hereditary HCM (n = 9), we embarked on the first-ever pilot study to examine the tissue-, urine-, and plasma-level proteomic and tissue-level transcriptomic effects of an intermittent low dose (0.15 mg/kg) and high dose (0.30 mg/kg) of DR oral rapamycin once weekly. Rapamycin remained safe and well tolerated in cats receiving both doses for eight weeks. Following repeated weekly dosing, transcriptomic differences between the low- and high-dose groups support dose-responsive suppressive effects on myocardial hypertrophy and stimulatory effects on autophagy. Differences in the myocardial proteome between treated and control cats suggest potential anti-coagulant/-thrombotic, cellular remodeling, and metabolic effects of the drug. The results of this study closely recapitulate what is observed in the human literature, and the use of rapamycin in the clinical setting as the first therapeutic agent with disease-modifying effects on HCM remains promising. The results of this study establish the need for future validation efforts that investigate the fine-scale relationship between rapamycin treatment and the most compelling gene expression and protein abundance differences reported here.

Hypertrophic cardiomyopathy in purpose-bred cats with the A31P mutation in cardiac myosin binding protein-C

We sought to establish a large animal model of inherited hypertrophic cardiomyopathy (HCM) with sufficient disease severity and early penetrance for identification of novel therapeutic strategies. HCM is the most common inherited cardiac disorder affecting 1 in 250-500 people, yet few therapies for its treatment or prevention are available. A research colony of purpose-bred cats carrying the A31P mutation in MYBPC3 was founded using sperm from a single heterozygous male cat. Cardiac function in four generations was assessed by periodic echocardiography and measurement of blood biomarkers. Results showed that HCM penetrance was age-dependent, and that penetrance occurred earlier and was more severe in successive generations, especially in homozygotes. Homozygosity was also associated with progression from preclinical to clinical disease. A31P homozygous cats represent a heritable model of HCM with early disease penetrance and a severe phenotype necessary for interventional studies aimed at altering disease progression. The occurrence of a more severe phenotype in later generations of cats, and the occasional occurrence of HCM in wildtype cats suggests the presence of at least one gene modifier or a second causal variant in this research colony that exacerbates the HCM phenotype when inherited in combination with the A31P mutation.

Circulating neutrophil extracellular traps in cats with hypertrophic cardiomyopathy and cardiogenic arterial thromboembolism

BACKGROUND

Cats with hypertrophic cardiomyopathy (HCM) are at risk of cardiogenic arterial thromboembolism (CATE). Neutrophil extracellular traps (NETs) may be a potential biomarker and therapeutic target for cardiomyopathy in cats.

HYPOTHESIS/OBJECTIVES

Characterize NETs in cats with HCM or CATE. We hypothesized that circulating NETs assessed in the form of cell-free DNA (cfDNA) and citrullinated histone H3 (citH3) are increased in cats with HCM and CATE and associated with reported predisposing factors for thrombus formation.

ANIMALS

Eighty-five cats including client-owned cats with HCM and CATE and staff- and student-owned clinically healthy cats without HCM.

METHODS

After echocardiographic evaluations, NETs were measured as cfDNA and citH3.

RESULTS

Cats with CATE had significant increases in cfDNA (11.2 ng/μL; interquartile range [IQR], 8.1 to 29.6) compared to those without HCM (8.2 ng/μL; IQR, 5.7 to 11.7 μL; P = .01) and were responsible for 75% to 83% of cases with cfDNA fragments sized 100 to 2000 base pairs. Citrullinated histone 3, detected in 52% of cats with HCM (31.1 ng/mL; IQR, 16.9 to 29.8), was significantly lower than in those with CATE (48.2 ng/mL; IQR, 34.2 to 60.2; P = .007). The citH3 concentrations correlated significantly with reported risk factors of CATE, such as left atrial auricular velocity.

CONCLUSIONS AND CLINICAL IMPORTANCE

Neutrophil extracellualr traps, especially citH3, are increased in cats with HCM and CATE. They may serve as a novel therapeutic target and biomarker of thrombosis in cats with HCM.

Echocardiographic evaluation of regurgitant fraction in dogs with subclinical myxomatous mitral valve disease: Method comparison, effects of pimobendan, and reproducibility

INTRODUCTION/OBJECTIVES

To evaluate regurgitant fraction (RF) using Simpson's method of discs to estimate total stroke volume (RF_{SMOD_TSV}) and using Motion-mode to estimate total stroke volume (RF_M-modeTSV) in dogs with subclinical myxomatous mitral valve disease (MMVD). We also sought to evaluate the effects of pimobendan on RF, and to determine the reproducibility of RF_{SMOD_TSV} and RF_M-modeTSV.

ANIMALS, MATERIALS, AND METHODS

Echocardiography was performed on 57 dogs with MMVD (30 stage B1 and 27 stage B2). Ten dogs received pimobendan for 7-10 days and had a second echocardiogram. Nine dogs underwent six repeated echocardiographic examinations by two operators on three nonconsecutive days within one week for reproducibility analysis.

RESULTS

Both RF_{SMOD_TSV} and RF_M-modeTSV exhibited a curvilinear relationship with left atrium-to-aortic root ratio. Both RF_{SMOD_TSV} and RF_M-modeTSV varied considerably within stage B1 (minimum-maximum: -9.1%-58.2% and -35.7%-66.2%, respectively) and B2 (13.6%-76.2% and 20.1%-85.7%, respectively). Method comparison showed RF_{SMOD_TSV} and RF_M-modeTSV were not interchangeable with proportional bias. Pimobendan significantly reduced RF_{SMOD_TSV} (-32.0% ± 23.3%) and RF_M-modeTSV (-19.2% ± 10.9%) within the same dog and relative to controls. Good inter-day and between-operator reproducibility was observed for RF_{SMOD_TSV} and RF_M-modeTSV based on intraclass correlation coefficients 0.86-0.90 and 0.83-0.90, respectively. Reproducibility coefficients were 19.6%-24.1% and 24.1%-27.0%, respectively.

CONCLUSIONS

Use of RF using the total stroke volume method to aid the assessment of dogs with subclinical MMVD might be of clinical value. However, further study is warranted. Based on response to pimobendan and reproducibility analysis, RF _{SMOD_TSV} might be a more reliable technique to quantify RF.

Pharmacokinetics of a single dose of Aficamten (CK-274) on cardiac contractility in a A31P MYBPC3 hypertrophic cardiomyopathy cat model

Hypertrophic cardiomyopathy (HCM) is the most prevalent cardiac disease in cats and lacks efficacious preclinical pharmacologic intervention, prompting investigation of novel therapies. Genetic mutations encoding sarcomeric proteins are implicated in the development of HCM and small molecule myosin inhibitors are an emerging class of therapeutics designed to target the interaction of actin and myosin to alleviate the detrimental effects of inappropriate contractile protein interactions. The purpose of this study was to characterize the pharmacodynamic effects of a single oral dose of the novel cardiac myosin inhibitor aficamten (CK-274) on cardiac function in purpose bred cats with naturally occurring A31P MYBPC3 mutation and a clinical diagnosis of HCM with left ventricular outflow tract obstruction (LVOTO). Five purpose bred cats were treated with aficamten (2 mg/kg) or vehicle and echocardiographic evaluations were performed at 0, 6, 24, and 48 h post-dosing. High dose aficamten (2 mg/kg) reduced left ventricular fractional shortening (LVFS%) by increasing the LV systolic internal dimension (LVIDs) and reduced isovolumic relaxation time (IVRT) compared with baseline without significant adverse effects. The marked reduction in systolic function and reduced IVRT coupled with an increased heart rate in treated cats, suggest a lower dose may be optimal. Further studies to determine optimal dosing of aficamten are indicated.

Effect of standard-dose and high-dose pimobendan on select indices of renal and cardiac function in dogs with American College of Veterinary Internal Medicine stage B2 myxomatous mitral valve disease

BACKGROUND

Pimobendan might have favorable effects on renal function but this has not been well-studied in dogs with myxomatous mitral valve disease (MMVD).

OBJECTIVES

Determine the effects of standard-dose (SD_pimo) and high-dose pimobendan (HD_pimo) on glomerular filtration rate (GFR) and cardiac size and function in dogs with preclinical MMVD.

ANIMALS

Thirty nonazotemic dogs with stage B2 MMVD.

METHODS

Prospective, randomized, double-blinded, placebo-controlled clinical study. Dogs had an echocardiographic examination, assessment of GFR (iohexol clearance), N-terminal probrain natriuretic peptide (NT-proBNP), and quality of life (QOL) score at baseline and 7 to 10 days after placebo (n = 6), SD_pimo 0.2 to 0.3 mg/kg q12 (n = 12), or HD_pimo 0.5 to 0.6 mg/kg q12h (n = 12).

RESULTS

No significant differences in GFR or QOL scores were detected between groups (P ≥ $$ \ge $$ .07). After HD_pimo, the mean [SD] percent change of NT_proBNP (-46.1 [20.2]%), left atrial volume (LAV; -27.1 [16.9]%), left ventricular end-diastolic volume (EDV; -21.8 [15.0]%), and end-systolic volume (ESV; -55.0 [20.7]%) were significantly different (P ≤ $$ \le $$ .004) from placebo (0.5 [19.9]%, 1.3 [15.6]%, -0.2 [8.2]%, -7.3 [35.6]%, respectively) but not the percent change after SD_pimo (-36.6 [16.1]%, -22.7 [14.9]%, -16.7 [12.5]%, -41.6 [14.8]%, respectively; P > .05). After SD_pimo, percent change of NT_proBNP, LAV, EDV, and ESV were significantly different from placebo (P < .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

Results suggest that pimobendan (SD_pimo or HD_pimo) might not affect renal function in nonazotemic dogs with stage B2 MMVD. High-dose pimobendan did not demonstrate advantages over SD_pimo within the constraints of our study.

Closure of a patent ductus arteriosus in a 2-week-old llama cria using an Amplatz canine duct occluder

A two-week-old female llama cria was brought to the UC Davis Large Animal Hospital for evaluation of a cardiac murmur and suspected syncopal episodes. A grade IV/VI left basilar continuous murmur was present on cardiac auscultation. Echocardiography revealed a left-to-right shunting patent ductus arteriosus (PDA), mild left ventricular enlargement, scant pericardial effusion, and a suspected persistent left cranial vena cava. The PDA was successfully closed with an Amplatz canine duct occluder. Mild mitral regurgitation was present on echocardiography performed 7 d following PDA occlusion. No syncopal episodes were observed in hospital prior to or following PDA occlusion. At approximately 1 mo following PDA closure, a grade I/VI left apical systolic murmur was present and the cria's body condition was improved. Key clinical message: Patent ductus arteriosus closure is achievable in New World camelids using interventional cardiology which provides a minimally invasive treatment option for valuable or companion animals. Since interventional cardiac catheterization is commonly performed in small animal species, veterinary cardiologists are well-equipped to apply these skills to camelids.

Biopsy of an intracardiac paraganglioma in a dog using a fluoroscopically guided endovascular technique

A 10‐year‐old female spayed mixed breed dog was evaluated for diarrhea and vomiting. Diagnostic imaging demonstrated the presence of an intracardiac mass. A modified Seldinger technique was used to access the right jugular vein, and an endomyocardial biopsy forceps was introduced through a sheath to obtain several biopsies. Histopathology and immunohistochemistry demonstrated a paraganglioma. The dog underwent 1 fraction of radiotherapy and l‐asparaginase chemotherapy and was discharged. The dog developed a pulmonary thromboembolism 2 days after radiotherapy and chemotherapy, and the owner elected humane euthanasia. Although long‐term assessment of treatment response was unable to be performed, this novel diagnostic option could be considered for similar cases due to success in obtaining a histopathologic diagnosis, which is essential in developing a disease‐specific treatment plan. This report also describes the use of radiotherapy for primary treatment of an intracardiac neoplasm, which can be a consideration in the future.

Fractional viscoelastic models for power-law materials

Soft materials often exhibit a distinctive power-law viscoelastic response arising from broad distribution of time-scales present in their complex internal structure. A promising tool to accurately describe the rheological behaviour of soft materials is fractional calculus. However, its use in the scientific community remains limited due to the unusual notation and non-trivial properties of fractional operators. This review aims to provide a clear and accessible description of fractional viscoelastic models for a broad audience and to demonstrate the ability of these models to deliver a unified approach for the characterisation of power-law materials. The use of a consistent framework for the analysis of rheological data would help classify the empirical behaviours of soft and biological materials, and better understand their response.

Development of plasma and whole blood taurine reference ranges and identification of dietary features associated with taurine deficiency and dilated cardiomyopathy in golden retrievers: A prospective, observational study

INTRODUCTION

A surge in Food and Drug Administration (FDA) consumer complaints identified concerns that legume-rich, grain-free diets were associated with nutritionally-mediated dilated cardiomyopathy (DCM). Golden retrievers represent the most reported breed affected by this condition and previous studies documented the disease is responsive to dietary change and taurine supplementation. Although dietary findings across cases are compelling, prospective studies with control groups are lacking. The role of diet in developing taurine deficiency and echocardiographic changes consistent with DCM in healthy dogs is unknown.

OBJECTIVES

We hypothesized that golden retrievers eating non-traditional diets are at a higher risk of having taurine deficiency and nutritionally-mediated DCM compared with those eating traditional commercial diets. We aimed to compare taurine concentrations and echocardiographic indices of systolic function between golden retrievers in each diet group and elucidate associations between diet and these variables. Additionally, we aimed to generate breed-specific reference intervals for whole blood and plasma taurine concentrations.

ANIMALS

86 golden retrievers.

METHODS

Golden retrievers eating traditional or non-traditional diets were evaluated and diet history, taurine concentrations and echocardiographic data were collected. Dietary features, taurine concentrations and echocardiographic findings were compared between diet groups. Relative risks were calculated for the likelihood of echocardiographic abnormalities and taurine deficiency in each diet group. Breed-specific reference intervals were constructed for taurine concentrations in dogs from the traditional diet group.

RESULTS

Golden retrievers eating non-traditional diets had significantly lower taurine concentrations and more frequent systolic dysfunction. Breed specific reference intervals are higher than previously reported across breeds.

CONCLUSIONS

Non-traditional diets, which were typically grain-free and contained legumes in this study, were significantly associated with and have increased relative risk for the identification of taurine deficiency and echocardiographic abnormalities consistent with nutritionally-mediated DCM. These findings were identifiable in the absence of clinical signs and support the findings of multiple previous studies and the ongoing FDA investigation.

Correction: Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets

[This corrects the article DOI: 10.1371/journal.pone.0209112.].

Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets

INTRODUCTION

Golden retrievers are over-represented in cases of taurine-deficient dilated cardiomyopathy and recently a surge in cases has prompted further investigation.

OBJECTIVE

To describe the clinical, dietary, and echocardiographic features in golden retrievers diagnosed with taurine deficiency and dilated cardiomyopathy, and to determine specific dietary associations. A second aim was to determine the whole blood taurine concentrations in a representative sample of healthy golden retrievers.

ANIMALS

Twenty-four client-owned golden retrievers with documented taurine deficiency and dilated cardiomyopathy and 52 healthy client-owned golden retrievers.

METHODS

In this multicenter prospective observational study, baseline and follow-up echocardiographic data, complete diet and medical histories, and whole blood, plasma, or serum taurine concentrations were obtained. Baseline and follow-up echocardiographic data were compared. Associations were evaluated between specific diets and taurine deficiency or congestive heart failure. The prevalence of low whole blood taurine concentrations in the healthy golden retrievers was calculated.

RESULTS

Twenty-three of 24 dogs diagnosed with taurine deficiency and dilated cardiomyopathy were fed diets that were either grain-free, legume-rich, or a combination of these factors. None of these diets were feeding trial tested using Association of American Feed Control Officials (AAFCO) procedures. Twenty-three of 24 dogs had significant improvement in their echocardiographic parameters and normalization of taurine concentrations following diet change and taurine supplementation. Nine of 11 dogs diagnosed with congestive heart failure (CHF) had resolution of their congestion at follow-up with five no longer requiring diuretic therapy and four tolerating diuretic dose reduction by >50%.

CONCLUSIONS

Certain diets and diet characteristics were associated with the development of taurine deficiency. Taurine deficiency and dilated cardiomyopathy in golden retrievers is likely multifactorial, including a combination of dietary, metabolic, and genetic factors.

Acute echocardiographic effects of sotalol on ventricular systolic function in dogs with ventricular arrhythmias

Background

Sotalol is a commonly used antiarrhythmic drug that may alter ventricular function.

Objective

To determine the effect of sotalol on echocardiographic indices of ventricular systolic function in dogs with ventricular arrhythmias.

Animals

Thirty‐five client‐owned dogs with ventricular arrhythmias.

Methods

Dogs with ventricular arrhythmias (n = 27) had an echocardiogram and 5‐minute ECG performed at baseline and 2‐4 hours post‐sotalol (2‐2.5 mg/kg PO once). Eight additional dogs underwent the same protocol but did not receive sotalol (within‐day variability controls). Left ventricular (LV) internal dimension at end‐systole normalized to bodyweight (LVIDs_N), LV ejection fraction (LV EF), LV shortening area, LV fractional shortening, tricuspid annular plane systolic excursion (TAPSE), and right ventricular systolic myocardial velocity were evaluated as indices of systolic function.

Results

All indices except TAPSE had mild decreases in systolic function post‐sotalol (all P ≤ .0007) compared with baseline but only the percent change in LVIDs_N and LV EF were significantly (P ≤ .0079) different from the percent change of the same indices in control dogs. Sinus heart rate, ventricular premature complexes/5‐minutes, and arrhythmia grade also were decreased post‐sotalol (all P ≤ .01) compared with baseline when assessed by a 5‐minutes ECG. No dog experienced an adverse event post‐sotalol, including dogs with systolic dysfunction or atrial enlargement.

Conclusions and Clinical Importance

A single dose of sotalol may cause a mild decrease in LV systolic function in dogs with ventricular arrhythmias. Sotalol appears to be well tolerated, even in dogs with atrial enlargement or systolic dysfunction.

Multiple midline defects identified in a litter of golden retrievers following gestational administration of prednisone and doxycycline: a case series

Background

The teratogenic effects of immunomodulatory and certain antimicrobial therapies are described in small rodents and humans. While the described teratogenic effects in small rodents have been extrapolated to make conclusions about its use in the pregnant dam, teratogenic effects of prednisone and doxycycline have not yet been reported in the dog. Here we report and describe midline defects observed in a litter of golden retriever puppies exposed to mid-gestational immunosuppressive and antimicrobial therapy.

Case presentation

Twenty-one days into gestation, the dam of a litter of eight golden retriever puppies was administered prednisone, doxycycline, and tramadol as treatment for immune-mediated polyarthritis. The individuals in the litter were subsequently diagnosed with a variety of midline defects and congenital cardiac defects. This case series describes the variety of identified defects and presents a descriptive account of complex congenital abnormalities that are likely secondary to teratogenic effects of one or more drugs administered during gestation. The available puppies, dam, and grand dam underwent thorough physical examination, complete echocardiogram, and where indicated, advanced imaging with various surgical corrections when possible.

Numerous midline congenital defects and congenital heart disease were identified in the puppies evaluated. Ultimately 5 of 8 puppies born to the dam were presented for thorough evaluation. The midline defects include: gastroschisis (1), peritoneopericardial diaphragmatic hernias (4, PPDH), umbilical hernia (4), unilateral cryptorchidism (1 of 4 males), cleft palate (1), renal agenesis (1), renal abnormalities (1), sternal and vertebral abnormalities (3), remnant liver lobe (1) and malformations consistent with ductal plate malformations with congenital hepatic fibrosis (1). The congenital cardiac defects include: ventricular septal defect (4, VSD) and subaortic stenosis (4, SAS). The presence of greater than one congenital defect was noted in all 5 of the dogs evaluated. Surgical correction was necessary for PPDH in 4 puppies. Medical intervention was recommended for congenital cardiac disease in 1 puppy.

Conclusion

This case report is the first to describe midline defects in dogs that have been exposed to immunomodulatory therapy during gestation. A causative relationship between mid-gestational immunomodulatory exposure and midline defects cannot be proven, however, this case supports a clear association and provides case-based evidence to support its avoidance when possible.

Adenosine A1 receptor antagonist prolongs survival in the hypoxic rat

The hypothesis that adenosine A1 receptor (A1AdoR) selective antagonism limits cardiac depression and prolongs survival during acute global hypoxia was tested in a postinsult treatment model using KW-3902 ([8-(noradamantan-3-yl)-1,3-dipropylxanthine]), an A1AdoR selective antagonist. Rats were anesthetized, paralyzed, then ventilated with 8% O2 (hypoxia). In protocol I, 5 min after hypoxia, rats were treated with saline, drug vehicle, or KW-3902 (0.1 mg/kg i.v.). In protocol II, KW-3902 treatment occurred 2.5, 5, or 7.5 min after hypoxia. In protocol I, after hypoxia, left ventricular contractility, heart rate, and systemic mean arterial blood pressure decreased rapidly in saline-and vehicle-treated groups. In contrast, KW-3902 significantly attenuated the decline in these variables. Survival time (the time from the commencement of hypoxia until death) was more prolonged with KW-3902 (109.5 +/- 9.1 min) than with saline (37.6 +/- 5.0 min) or vehicle (35.0 +/- 4.2 min) (p < 0.001). In protocol II, survival time increased from 29.2 +/- 5.5 min in the 7.5-min treatment group to 109.5 +/- 9.5 min (5-min group) and 245.9 +/- 26.1 min (2.5-min group; p < 0.001). KW-3902 prolongs survival in this model, presumably by antagonizing A1AdoR-mediated inhibition of cardiac function. Also, treatment efficacy is highly time dependent.

What is gross hematuria? Correlation of subjective and objective assessment

BACKGROUND

Gross hematuria is a screening test used to help determine the need for radiographic evaluation in patients with blunt trauma. This subjective assessment has not been compared with objective measures, nor has interrater reliability been described.

METHODS

We performed a prospective, randomized, controlled study to determine the ability of clinicians to assess gross hematuria. Clinicians were asked to assess samples containing various concentrations of blood diluted in urine for the presence of gross hematuria.

RESULTS

Gross hematuria was recognized by more than 95% of clinicians only when samples contained more than 3,500 red blood cells per high-power field. Clinicians' interpretations were independent of profession, specialty, and level of training (p > 0.08).

CONCLUSION

Clinicians demonstrate poor sensitivity and interrater reliability identifying gross hematuria by inspection. Clinical studies correlating degrees of hematuria to the need for genitourinary diagnostic evaluation should report both subjective and objective measures to identify a threshold value predictive of renal injury.

The effect of lower-extremity position on cerebrospinal fluid pressures

OBJECTIVE

To determine the effects of lower-extremity positioning on cerebrospinal fluid opening pressure (CSFp). The authors believed that during lumbar puncture (LP), CSFp does not meaningfully decrease when the lower extremities are extended from flexion, as is often suggested.

METHODS

In a convenience sample of adult patients who clinically required LP in an urban emergency department, three sequential CSFp measurements were obtained in either sequence A (knee, hip, and neck flexion [90 degrees ], then extension, then flexion) or sequence B (extension, flexion, then extension) prior to CSF withdrawal. The neck was flexed at 30 degrees when the lower extremities were flexed, while the thoracolumbar spine was kept in the neutral position for all measurements.

RESULTS

Nineteen patients were studied in each sequence. Although variable, overall within-patient changes between positions were not clinically meaningful. Mean and 95% confidence intervals (95% CIs) for the decrease in CSFp from position 1 to position 3 (same position) were 0.2 cm H(2)O (1.7%) and 0.9 to -0.6 cm H(2)O (6% to -2.7%), respectively. Changing from flexion to extension decreased pressure measurements by a mean of 0.9 cm H(2)O (2.5%) [95% CI = 2.1 to -0.1 cm H(2)O (7.6% to -2.4%)]. Changing from extension to flexion increased CSFp by a mean of 1.1 cm H(2)O (6.1%) [95% CI = 0.2 to 2.0 cm H(2)O (1.3% to 11.5%)], a statistically but not clinically meaningful change.

CONCLUSIONS

Changing lower-extremity position did not meaningfully change mean CSFp. These data do not support the common suggestion that extending the lower extremities during LP meaningfully decreases CSF opening pressures.

An Exact Solution to the Electrostatic Interaction between an Ion-Penetrable Sphere and an Ion-Penetrable Rod

No exact solution for the free energy of electrostatic interaction for a charged sphere and rod geometry in an electrolyte solution has yet been proposed. This geometry is interesting because it can be applied to describe macromolecules interacting with a random fiber-matrix for modeling of hindered transport in diffusional systems. Here we present an analytical approach that yields an exact solution to the problem for ion-penetrable-also called "soft"-sphere and infinitely long rod. This solution is compared to a published finite-element analysis of the same system with nonpenetrable-also called "hard"-sphere and infinitely long rod maintaining a constant surface charge density restriction. For any ionic strength or ratio of rod radius to sphere radius the ion-penetrable method yields an electrostatic free energy of interaction which is lower than that given by the analysis for hard bodies. This free energy is significantly lower for most parameter value combinations and therefore suggests that one should carefully examine the system being modeled to determine if it is approximated better by a hard body or ion-penetrable body approach. Copyright 2000 Academic Press.

Hypertonic saline treatment of severe hyperkalemia in nonnephrectomized dogs

OBJECTIVES

To determine whether a hypertonic saline bolus improves cardiac conduction or plasma potassium levels more than normal saline infusion within 15 minutes of treatment for severe hyperkalemia. Previously with this model, 8.4% sodium chloride (NaCl) and 8.4% sodium bicarbonate (NaHCO(3)) lowered plasma potassium equally effectively.

METHODS

This was a crossover study using ten conditioned dogs (14-20 kg) that received, in random order, each of three intravenous (IV) treatments in separate experiments at least one week apart: 1) 2 mmol/kg of 8.4% NaCl over 5 minutes (bolus); 2) 2 mmol/kg of 0.9% NaCl over one hour (infusion); or 3) no treatment (control). Using isoflurane anesthesia and ventilation (pCO(2) = 35-40 torr), 2 mmol/kg/hr of IV potassium chloride (KCl) was infused until conduction delays (both absent p-waves and >/=20% decrease in ventricular rate in </=5 minutes) were sustained for 15 minutes. The KCl was then decreased to 1 mmol/kg/hr (maintenance) for 2 hours and 45 minutes. Treatment (0 minutes) began after 45 minutes of maintenance KCl.

RESULTS

From 0 to 15 minutes, mean heart rate increased 29.6 (95% CI = 12.2 to 46; p < 0.005) beats/min more with bolus than infusion and 23.4 (95% CI = 2.6 to 43.5; p < 0.03) beats/min more with bolus than control. No clinically or statistically significant difference was seen in heart rate changes from 0 to 30 minutes. Decreases in potassium from 0 to 15 minutes were similar with bolus, infusion, and control.

CONCLUSIONS

In this model, 8.4% NaCl bolus reversed cardiac conduction abnormalities within the first 15 minutes after treatment, more rapidly than did the 0.9% NaCl infusion or control. This reversal occurred despite similar reductions in potassium levels.

Use of an unmanned police car to reduce traffic speed

OBJECTIVE

Motor vehicle collisions are the most common mechanism of traumatic death. Speeding is often implicated as a causal factor in motor vehicle crashes. One potential intervention, to prevent speeding, is the placement of a roadside unmanned police car. This study sought to answer the following questions: is speeding reduced by this intervention, does this intervention lose effectiveness over time, and when the car is removed, do motorists resume speeding?

METHODS

A radarless speed detector was placed on a roadway that had a history of speed-related collisions. Baseline speeds were recorded for 12 days. Thereafter, an unmanned police cruiser was parked near the road, and speeds were recorded for 10 days. The police car was removed, and data collection continued 1 more week. The difference between the proportion of motorists exceeding 45-mph in the baseline period and the decoy intervention period was tested by using a chi2 test.

RESULTS

During the baseline surveillance, 72.0% of vehicles (186,578 of 259,074 motorists) had speeds greater than 45 mph. After placement of the unmanned police car, 41.0% of motorists (92,272 of 225,026 motorists) exceeded 45 mph (p < .0001). Over the 10-day study period, when the decoy police car was in place, the percentage of motorists exceeding 45 mph gradually increased from 27.2% to 47.4%. Upon removal of the police car, speeding returned approximately to baseline, with 67.5% of motorists (120,640 of 178,752 motorists) exceeding 45-mph.

CONCLUSION

Parking an unmanned police car beside a road was associated with a large reduction in speeding over a 10-day period. Removal of the unmanned police car resulted in a return to preintervention speeding.

Antagonism of the cardiodepressant effects of adenosine during acute hypoxia

OBJECTIVE

To determine whether pharmacologic antagonism of adenosine A1-receptor-mediated cardiovascular changes can improve cardiac function and prolong survival during systemic hypoxia.

METHODS

Rats were anesthetized with ketamine, instrumented [including left ventricular (LV) pressure transducing catheters], paralyzed with vecuronium, then ventilated to pCO2 = 35-40 torr. After 10 minutes of equilibration (baseline), treatment commenced with saline (n = 7), NPC-205, an adenosine A1 receptor selective antagonist, at doses of 1 mg/kg (n = 10) or 10 mg/kg (n = 10), or drug vehicle (n = 9). Ten minutes later, inspired oxygen was reduced to 5%.

RESULTS

Survival duration (min) post-hypoxia increased in a dose-dependent fashion from 10.4 +/- 1.4 (mean +/- SEM) with vehicle control to 23.0 +/- 4.7 and 41.1 +/- 5.7 with 1 and 10 mg/kg NPC-205, respectively (p < 0.000). Five minutes post-hypoxia, dose-dependent increases were also seen in the percentage of pre-hypoxic values of LV contractility [25.9 +/- 8.1 (vehicle), 39.5 +/- 9.6 (1 mg/kg NPC-205), and 56.5 +/- 8.7 (10 mg/kg NPC-205), p = 0.01], heart rate [60.6 +/- 8.3 (vehicle), 74.7 +/- 8.2 (1 mg/kg NPC-205), and 90.4 +/- 24.1 (10 mg/kg NPC-205), p = 0.02], and blood pressure [16.1 +/- 4.8 (vehicle), 28.8 +/- 8.6 (1 mg/kg NPC-205), and 51.7 +/- 8.2 (10 mg/kg NPC-205), p = 0.004].

CONCLUSIONS

The adenosine A1 selective antagonist prolonged survival in this model. This prolongation was attributed to inhibition of adenosine A1 receptor-mediated decline in cardiac inotropy and chronotropy. Adenosine A1 receptor-selective antagonists show promise as adjunctive therapy for hypoxia-induced cardiac insufficiency by prolonging the treatment window until more definitive resuscitation measures are taken.

Cost-based comparison between perforator flaps and TRAM flaps for breast reconstruction

More women than ever before are undergoing mastectomies secondary to increased awareness and screening. This increase has also caused a corresponding increase in the number of breast reconstructions requested each year. The increased demand for reconstruction has fueled recent advances in new techniques. Aside from foreign-body reconstruction such as implants, the methods now being used are related to autogenous donations and reconstruction. Transverse rectus abdominis myocutaneous (TRAM) flaps and perforator flaps are currently being used for autogenous breast reconstruction. This study will compare these two techniques on the basis of cost and length of stay. A retrospective study of 49 patients undergoing a total of 64 perforator flap breast reconstructions at Memorial Medical Center in New Orleans, Louisiana, during the 1997 calendar year was used. There were 59 deep inferior epigastric perforator and five gluteal artery perforator breast reconstructions. All patients underwent some form of breast reconstruction and differed only in respect to whether a mastectomy was performed and whether the reconstruction was unilateral or bilateral. Those patients who underwent a mastectomy with immediate perforator flap reconstruction (n = 26) were then compared with patients undergoing mastectomy with immediate TRAM flap reconstruction (n = 154) at the University of Texas M. D. Anderson Cancer Center. The data from the Anderson Study were obtained from material published in Plastic and Reconstructive Surgery in 1996. Comparison of patients was limited to those who underwent mastectomy with immediate breast reconstruction because this was the design of the M. D. Anderson study. This approach allowed a cost and length of stay comparison while keeping other variables relatively similar. Patients in the perforator flap series enjoyed a marginally shorter operating time and a much shorter length of stay. On average, the operative time for all perforator flap reconstructions was approximately 2 hours shorter than for all TRAM flaps. As for length of stay, perforator flap patients were discharged, on average, 3 days after the initial reconstruction. In contrast, TRAM flap patients remained in the hospital for an average of approximately 7 days after the initial reconstruction. The overall total, average cost for the perforator flap reconstruction in this study is $9625, whereas the average cost of all TRAM flaps performed in the Anderson study is $18,070.

Double-blind, randomized study of nalmefene and naloxone in emergency department patients with suspected narcotic overdose

STUDY OBJECTIVES

To compare the efficacy, safety, and withdrawal symptoms in emergency department patients with suspected narcotic overdose treated with nalmefene, an opioid antagonist with a 4- to 10-hour duration of action, with those treated with naloxone.

METHODS

Adults in 9 centers who would otherwise receive naloxone for altered consciousness levels were randomly assigned to receive intravenous study drug (1 mg nalmefene, or 2 mg nalmefene or 2 mg naloxone, double-blinded) every 5 minutes as needed for up to 4 doses in a 4-hour study. Outcomes were 20-minute and 4-hour posttreatment changes in respiratory rates, Neurobehavioral Assessment Scale scores, Opioid Withdrawal Scale scores, and incidences of adverse events.

RESULTS

Opioid positivity was recorded for 30 of 63 (1-mg nalmefene), 23 of 55 (2-mg nalmefene), and 24 of 58 (naloxone) cases, 75% of whom also had nonopioid central nervous system depressants. Most patients received only 1 dose of study drug. Similar, clinically meaningful improvements in respiratory rates and Neurobehavioral Assessment Scale scores were seen with all treatments. No statistical differences in efficacy or withdrawal outcomes were seen between treatment groups, and no significant overall time-treatment interactions occurred, in either the entire patient group or among opioid-positive cases (P >.21, all comparisons). Adverse events occurred in 30.9% (2 mg nalmefene), 15.9% (1 mg nalmefene), and 15.5% (naloxone) of patients (P >.08); none were associated with morbidity.

CONCLUSION

In this study of patients with varied potential causes of altered consciousness, nalmefene (1 mg and 2 mg) and naloxone (2 mg) appeared to be efficacious, safe, and to yield similar clinical outcomes.

Use of tube condensation as an indicator of endotracheal tube placement

STUDY OBJECTIVE

To determine whether condensation on the inner surface of the endotracheal tube (vapor trail) is a reliable indicator of intratracheal placement.

METHODS

Twenty-seven separate experiments were conducted on 10 conditioned, mongrel dogs weighing 15 to 20 kg each. After induction of anesthesia, an endotracheal tube was placed in the trachea under direct visualization. A second, identical endotracheal tube was then placed in the esophagus. An attending emergency physician, blinded to tube placement, then used a bag-valve apparatus to manually ventilate each endotracheal tube in turn. Five ventilations were performed on each tube, and the presence or absence of condensation on the inner surface of the tube was recorded. A second physician, blinded both to tube placement and to the actions of the first assessor, then repeated the ventilation and assessment of both tubes.

RESULTS

Vapor trail was observed in 27 (100%) of 27 endotracheal tubes correctly placed in the trachea (95% confidence interval [CI], 90% to 100%) and in 23 (83%) of 27 tubes placed in the esophagus (95% CI, 66% to 96%). Physicians concurred in all cases. Absence of vapor trail was 15% sensitive (95% CI, 4% to 34%) for indicating incorrect (esophageal) tube placement.

CONCLUSION

In this model, condensation on the inner surface of the endotracheal tube was common after placement within the esophagus. If these results are confirmed in human studies, the presence of a vapor trial should not be used as a clinical indicator of correct endotracheal tube placement.

Alkalinization is ineffective for severe hyperkalemia in nonnephrectomized dogs. Hyperkalemia Research Group

OBJECTIVE

To determine whether alkalinization with sodium bicarbonate (NaHCO3) in near-lethal hyperkalemia either lowers potassium (K) rapidly or shortens duration of cardiac conduction disturbances.

METHODS

A controlled canine laboratory investigation of 3 treatments for severe hyperkalemia. Conditioned dogs (n = 8; 17-30 kg) received, in random order, 2 mmol/kg of each of 3 treatments (matched in sodium and water) in separate experiments > or = 1 week apart: 1.05% NaHCO3 over 60 minutes (infusion therapy); 8.4% NaHCO3 over 5 minutes, then 14 mL/kg sterile water over 55 minutes (bolus therapy); 8.4% NaCl over 5 minutes, then 14 mL/kg sterile water over 55 minutes (saline therapy). Prior to administering one of the above therapies, the animals were anesthetized with 0.5-2.5% isoflurane and ventilated to maintain a normal PCO2. After 30 minutes of equilibration, 2 mmol/kg/hr (loading dose) of a 2-mmol/mL KCl solution was given until idioventricular or relative junctional bradycardic dysrhythmias were sustained for 15 minutes. Then KCl was decreased to 1 mmol/kg/hr (maintenance dose) for 2 hours and 45 minutes. Treatment was begun after 45 minutes of maintenance KCl infusion.

RESULTS

The pretreatment K level (all studies) was 9.06 +/- 0.82 mmol/L (mean +/- SD). Although the mean K level decreased more after saline therapy than after bolus therapy at every time, differences were neither statistically significant nor clinically important during the first 30 minutes. The means of the differences in decreases (saline minus bolus) were small, 0.26 (95% CI, -0.48 to 1.00) at 15 minutes, 0.16 (95% CI, -0.67 to 0.98) at 30 minutes. Dysrhythmia duration was shorter with bolus therapy than for saline therapy in only 1 of 5 dogs (p = 0.38).

CONCLUSIONS

Hypertonic saline bolus lowered plasma K as effectively as NaHCO3 bolus in this animal model within the first 30 minutes. Clinically meaningful decreases due to alkalinization alone within 30 minutes are unlikely.

Posttraumatic osseous tunnel formation causing sciatic nerve entrapment

Sciatic nerve entrapment in an osseous tunnel has only been reported twice previously. We describe a 19-year-old man evaluated for left lower limb pain and weakness that began one and one half years after sustaining stab wounds to the left buttock and midline back near the T11 vertebrae. The patient had sciatica and demonstrated motor and sensory deficits on physical exam. Electrodiagnostic studies demonstrated a localized injury to the sciatic nerve in the proximal thigh. Radiographic studies of the left pelvis and femur showed an 8 to 10cm linear opacification overshadowing the left femoral head and anatomic neck. An arteriogram of the left leg demonstrated a 3 x 4cm lobulated aneurysm arising from the distal portion of the inferior gluteal artery. Surgical exploration revealed the sciatic nerve to be encased in cylindrical bone. The ectopic bone was removed and the sciatic nerve released. The patient had gradual improvement with a nearly complete neurological recovery by three months after surgery.

Effectiveness and safety of intravenous nalmefene for emergency department patients with suspected narcotic overdose: a pilot study

STUDY OBJECTIVE

To evaluate the efficacy and safety of nalmefene, an investigational narcotic antagonist that has potential advantages over naloxone because of its four- to eight-hour half-life, in emergency department patients with possible narcotic overdose.

DESIGN

Multi-institutional, prospective, phase II, open-label study.

TYPE OF PARTICIPANTS

Complete data were available for 53 cases from two teaching hospitals. Men 18 years old or older who would otherwise receive naloxone were eligible (two women were enrolled inadvertently).

METHODS

Over four hours, one to ten boluses (median, one) of 0.5 or 1.0 mg nalmefene IV were given as often as every two minutes based on clinical need. Respirations, blood pressure, pulse, pupil size, and overall clinical response were monitored. Overall clinical response (1, no change; 2, partial response; 3, complete response), first assessed at two minutes, was analyzed by the Mann-Whitney U test.

RESULTS

Fifteen of 25 (0.5 mg) and nine of 28 (1.0 mg) cases were opiate positive. Twelve of 15 (0.5 mg) and six of nine (1.0 mg) opiate-positive cases had a rapid complete response. Coincident causes of depressed sensorium were identified in the remaining six opiate-positive cases. No difference in initial overall clinical response was seen between 0.5-mg and 1.0-mg opiate-positive cases (P = .59). No deterioration requiring repeat nalmefene occurred in opiate-positive cases, even if methadone (four), codeine (two), or pentazocine (one) was found. No serious adverse events were judged to be related to nalmefene.

CONCLUSION

Nalmefene is effective in the reversal of opiate overdose and appears to be safe in the management of patients with altered sensorium.