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Biomedical subjects

A M Hoffman

Publications and source records attributed to A M Hoffman.

At least 19 recordsLinked to original sources
PubMed2006

Behavioural lateralisation in the Australian magpie (Gymnorhina tibicen).

In many vertebrates, the brain is lateralised such that each hemisphere is specialised to serve specific functions. This may translate into lateralisation in behaviour through preferential use of receptors or appendages associated with a particular hemisphere (e.g., handedness) or in differential responses to stimuli perceived on the animal's left or right side. In this study, we investigated behavioural laterality in the Australian magpie, Gymnorhina tibicen. We found that, while the birds did not have a population bias for one antipredator behaviour (visual inspection of an approaching human), there were biases for another (alarm calling); those birds that used their left eye more relative to their right eye gave alarm calls more frequently. We also observed that juvenile birds begged for food on the right side of parents significantly more frequently than on the left side. These trends are consistent with trends in behavioural laterality that have been recorded in captive and lab-reared species. Ours is one of the few studies to observe patterns of laterality in a wild species.

Animals↗
PubMed2005

Canine awake head-out plethysmography (HOP): characterization of external resistive loading and spontaneous laryngeal paralysis.

We applied a novel head-out plethysmographic (HOP) method to study awake canine responses to external resistive loading and natural laryngeal paralysis. Measurements of inspiratory and expiratory specific airway resistance (sRaw(insp), sRaw(exp)) were obtained before and after uni- and bidirectional loading (R(add) = 5 cmH(2)O/L/s) in large-breed dogs (n = 9). Mean sRaw(insp) after inspiratory, and sRaw(exp) after expiratory loading were 31.4 and 33.3 cmH(2)Os, respectively. Bidirectional loads induced a significantly greater rise in both sRaw(insp) and sRaw(exp) (55.1 and 61.3 cmH(2)Os) compared to unidirectional loading (P < 0.001). Yet, type of loading did not affect flow-volume indices. The mean R(aw) of dogs was 4.81 cmH(2)O/L/s. Expiratory loading resulted in a significant 8.8% increase in functional-residual-capacity (FRC), compared to FRC(baseline) (76.7 ml/kg). Dogs (n = 5) with laryngeal paralysis demonstrated a significant increase in sR(aw) and R(aw) compared to controls without changes in FRC. In conclusion, HOP precisely characterized sR(aw) in response to external resistive loading. Hence, we could accurately quantify airway obstruction in awake dogs with laryngeal paralysis.

Airway Resistance↗
PubMed2005

Radiographic scoring lacks predictive value in inflammatory airway disease.

REASONS FOR PERFORMING STUDY: Diagnosis of inflammatory airway disease (IAD) currently rests upon the results of bronchoalveolar lavage (BAL) cytology, lung function testing and histamine bronchoprovocation (HBP), none of which provides direct information about structural change in the lung. HYPOTHESIS: That thoracic radiography might better portray structural change in the lungs and therefore offer a good clinical assessment of IAD. METHODS: A radiographic scoring system was developed to assess the extent of bronchial and interstitial pattern on thoracic radiographs in the dorsocaudal, dorsocranial and caudoventral regions in 16 control horses and 33 horses with IAD. Mean scores were compared to ascertain whether thoracic radiographs could distinguish between the 2 groups. In order to determine whether independent observers reliably scored radiographs similarly, an inter-rater reliability score was employed for each radiographic observation. Correlations between radiographic scores, BAL cytology, lung function testing using the forced oscillatory technique and HBP were examined. RESULTS: Inter-rater reliability was only moderate. Radiographic scoring demonstrated no differences between the 2 groups. There were no correlations among BAL cytology, lung function testing, HBP and radiographic scores. CONCLUSIONS AND POTENTIAL RELEVANCE: Thoracic radiographs are a low-yield diagnostic modality in horses with a clinical history compatible with IAD. In the absence of clinical evidence of more extensive, infectious disease, thoracic radiographs neither refine nor improve diagnosis of IAD, but increase diagnostic costs.

Animals↗
PubMed2001

Vestibular signs associated with suspected lightning strike in two horses.

Two previously healthy 14-year-old horses developed right-sided unilateral vestibular signs after they had possibly been struck by lightning. Repeated radiographic and endoscopic evaluations did not reveal any significant changes. A brainstem auditory evoked response test indicated a subtle left to right interaural latency difference of waves I, III and V in the more severely affected pony, but its central conduction time remained normal.

Animals↗
PubMed2001

Respiratory applications for the future: one perspective.

Respiratory diagnostic instruments previously available only to referral centers should be converted into miniature, portable, wireless medical devices for use in practice. Internet and wireless connections of these instruments should expedite the process of seeking second opinions and in general information sharing. We are moving into a world of greater objectivity that should free us from speculation in some areas, yet open new avenues for research and innovation in others.

Animals↗
PubMed2001

Development of a standardized nomenclature for bronchoscopy of the respiratory system of harbor porpoises (Phocoena phocoena).

Respiratory disease is common in captive and wild cetaceans. Bronchoscopy may permit early diagnosis of respiratory disease in dolphins and porpoises. Refinement of cetacean bronchoscopy requires development of a nomenclature system to facilitate description of the anatomic site at which lesions occur. A standard bronchoscopic nomenclature also permits serial evaluations of lesions and enhances communication between veterinarians. In this project, we adapted the bronchoscopic nomenclature devised by Amis and McKiernan for the dog and horse to the harbor porpoise (Phocoena phocoena). Silastic and air-dried models of the bronchial tree of the harbor porpoise were made to illustrate the anatomy and devise the nomenclature. Bronchial anatomy was consistent among the four porpoise lungs studied. The Amis and McKiernan nomenclature was readily adaptable to the harbor porpoise lung with minor modifications and may be useful for cetacean bronchoscopy.

Animals↗
PubMed2001

Effects of aerosolized albuterol on physiologic responses to exercise in standardbreds.

OBJECTIVE: To examine the effects of an aerosolized beta2-adrenoreceptor agonist, albuterol, on performance during a standardized incremental exercise test in clinically normal horses. ANIMALS: 8 Standardbred pacing mares. PROCEDURE: Clinically normal horses, as judged by use of physical examination, hematologic findings, serum biochemical analysis, and airway endoscopy, were randomly assigned to 2 groups and were given 900 microg of albuterol via a metered-dose inhaler 30 minutes before beginning a standardized incremental exercise test in a crossover design with a 7-day minimum washout. Further examination included measurement of baseline lung mechanics, response to histamine bronchoprovocation, and bronchoalveolar lavage. RESULTS: No significant differences (albuterol vs placebo) were seen for any incremental exercise test variables (ie, maximum oxygen consumption, maximum carbon dioxide consumption, respiratory quotient, treadmill speed at heart rate of 200 beats/min, or number of steps completed during an incremental exercise protocol). Mast cell percentage was significantly (r = -0.84) associated with the concentration of aerosolized histamine that evoked a 100% increase in total respiratory system resistance. No other direct correlations between bronchoalveolar lavage fluid cell types and any indices of exercise capacity or airway reactivity were found. CONCLUSIONS AND CLINICAL RELEVANCE: Although no horse had exercise intolerance, 4 horses had airway hyperreactivity with bronchoalveolar lavage fluid mastocytosis; these horses may have been subclinically affected with inflammatory airway disease. In our study, albuterol did not enhance performance in 8 clinically normal racing-fit Standardbreds.

Adrenergic beta-Agonists↗
PubMed2000

Thoracoabdominal asynchrony failed to grade airway obstructions in foals.

Respiratory inductive plethysmography (RIP) can be used to obtain a valid measure of tidal volume in humans. This device also compares the contributions to ventilation of the thorax and abdomen. Although thoracoabdominal asynchrony is a prominent clinical feature for patients with airway obstruction, the accuracy of the RIP device to assess the severity of obstruction is unclear. This study analyzes how well RIP variables reflect the degree of a fixed external inspiratory plus expiratory resistive load in foals. Foals were employed because the species and age group are commonly afflicted with respiratory disease. Eight conscious, sedated (xylazine 1.25 mg/kg body wt) foals were subjected to randomly ordered resistive loads at the airway opening and, on a separate day, to histamine aerosol challenge. During resistive loading, phase angle changed significantly, as did phase relation (P < or = 0.05). However, no significant correlation was found between the degree of change in resistive load and the degree to which phase angle or relation was altered (r(s) = 0.41 and 0.25, respectively). In addition, neither phase angle nor relation changed significantly with histamine challenge. We conclude that, although RIP variables changed markedly with fixed upper airway resistive loading, the degree to which they changed was erratic and therefore not useful for grading these obstructions. Furthermore, RIP variables were insensitive measures of histamine-induced bronchoconstriction.

Abdomen↗
PubMed1999

Efficacy of tacrolimus in the treatment of refractory rejection in heart and lung transplant recipients.

BACKGROUND: Refractory acute cellular rejection may occur despite triple-drug immunosuppression (cyclosporine A, steroids, azathioprine/mycophenolate mofetil). The purpose of this study was to determine the efficacy of tacrolimus rescue therapy in patients maintained on cyclosporine-based immunosuppression (CBI). METHODS: Between December 1993 and October 1996, 208 patients underwent thoracic organ transplantation at the Hospital of the University of Wisconsin at Madison. One hundred forty-nine patients underwent heart replacement; 59 underwent lung transplantation. One hundred thirty-nine of the heart transplant cohort received CBI preceded by induction therapy with OKT3. Forty-six of the lung transplant cohort received CBI without induction cytolytic therapy. Refractory rejection was defined as failure to respond to high-dose steroids (500 mg to 1 g IV methylprednisolone for 3 days) and/or monoclonal antibody therapy (OKT3, 5 to 10 mg IV/day for 7 to 14 days). In patients with refractory rejection, cyclosporine was replaced with tacrolimus. RESULTS: Overall, 16% (30/185) of patients receiving CBI experienced refractory rejection. Thirty-one episodes of grade IIIa or greater rejection occurred in 11% (15/139) of heart transplant recipients. Twenty episodes of grade II to IV rejection occurred in 33% (15/46) of lung transplant recipients. After tacrolimus rescue therapy, 93% (14/15) of patients in the heart transplant group converted to grade II or less rejection. Refractory rejection was reversed in 73% (11/15) of the lung transplant group. Reversal was documented at biopsy in all (8/8) lung recipients in whom it had been histologically identified. FEV1 values of 3 additional patients stabilized. CONCLUSIONS: The incidence of refractory rejection in thoracic organ transplant recipients on CBI is significant. Reversal of refractory rejection follows rescue immunotherapy with tacrolimus.

Acute Disease↗
PubMed1999

Pulmonary function testing in small animals.

Pulmonary function testing (PFT) may be used to help provide objective information concerning the respiratory system in dogs and cats. Available techniques for PFT include spirometry, tidal breathing flow-volume loop analysis, barometric whole-body plethysmography, dynamic and static compliance, and lung and upper airway resistance. The information gained from PFT may help both in patient management and also in gaining understanding of the pathophysiology of the pulmonary system.

Animals↗
PubMed1999

Comparison of forced oscillation with the conventional method for histamine bronchoprovocation testing in horses.

OBJECTIVE: To compare response of horses to histamine bronchoprovocation (HBP), using total respiratory resistance (Rrs) measured by forced oscillatory mechanics (FOM) with dynamic compliance (Cdyn) and pulmonary resistance (RL) measured by the esophageal balloon method. ANIMALS: 10 horses with various degrees of airway reactivity. PROCEDURE: The 2 methods for measuring airway responses to HBP were performed on separate days. Endpoints compared were increase of 150 or 200% of baseline Rrs (PC150Rrs, PC200Rrs) and to 150% of baseline RL (PC150RL) or decrease to 65% of baseline Cdyn (PC65Cdyn). Frequency dependence of respiratory mechanics, using FOM, was evaluated, using the slope of Rrs over 1 to 3 Hz and the ratios of Rrs at 1 Hz to Rrs at 2 and 3 Hz (Rrs1Hz/Rrs2Hz, Rrs1Hz/Rrs3Hz) and of Rrs at 2 Hz to Rrs at 3 Hz (Rrs2Hz/Rrs3Hz). Effect of histamine on frequency dependence was assessed. RESULTS: Correlation with PC65Cdyn was high for PC150Rrs (rs = 0.93) and PC200Rrs (rs = 0.96). Correlation between PC65Cdyn and PC150RL was weakly positive (rs = 0.61). The slope of Rrs over 1 to 3 Hz changed significantly between baseline (-0.07+/-0.09 cm H2O/L/s/Hz) and final histamine dose (-0.28+/-0.10 cm H2O/L/s/Hz). The Rrs1Hz/Rrs3Hz and Rrs2Hz/Rrs3Hz differed significantly (P < 0.05 between baseline [1.27+/-0.36 and 0.96+/-0.11, respectively] and final histamine dose [1.62+/-0.37 and 1.09+/-0.14, respectively]). CONCLUSIONS: Correlation between histamine-induced changes in respiratory mechanics, as measured by FOM and the pneumotachograph-esophageal balloon method, was good. The FOM results indicated frequency dependence of respiratory mechanics during HBP. CLINICAL RELEVANCE: A noninvasive method of measuring airway reactivity will facilitate routine evaluation of horses with suspected small airway disease and may be suitable for field studies.

Airway Resistance↗
PubMed1999

Airway responses to histamine aerosol in clinically normal foods.

OBJECTIVE: To describe the spectrum of nonspecific airway reactivity in a group of clinically normal foals. ANIMALS: 12 clinically normal mixed-breed foals, 48 to 92 days old, without history of clinical lung disease. PROCEDURE: Nonspecific airway reactivity was determined by measuring the extent of changes in dynamic compliance during nebulization of incrementally increasing concentrations of histamine aerosol. Degree of airway reactivity was expressed as the dose of histamine that evoked a decrease in dynamic compliance (Cdyn) to 65% of the after saline nebulization value (PC65Cdyn) or increase in pulmonary resistance (R(L)) to 135% of baseline (PC135R(L)). RESULTS: In all foals, it was possible to induce a decrease in Cdyn in dose-dependent manner to < or = 65% of baseline. Response of foals in terms of R(L) was more erratic, and, in 1 foal, R(L) decreased after histamine exposure. Mean+/-SD PC65Cdyn was 5.43+/-1.74 (range, 0.77 to 19.56) mg/ml, and mean PC135R(L) was 3.34+/-1.52 (range, -0.749 to 17.35) mg/ml. Body weight was not correlated to baseline Cdyn, R(L), PC65Cdyn, or PC135R(L). CONCLUSIONS AND CLINICAL RELEVANCE: Clinically normal foals had a wide range of airway reactivity, which may contribute to variation in clinical responses of foals to otherwise similar stimuli, such as infection, inflammation, and challenge exposure with environmental irritants.

Aerosols↗
PubMed1999

Airway reactivity measured by barometric whole-body plethysmography in healthy cats.

OBJECTIVE: To assess the validity of barometric whole-body plethysmography (BWBP) as a means of monitoring airway responses to induced bronchoconstriction in healthy cats. ANIMALS: 8 healthy cats without history of bronchopulmonary disease or exposure to indoor tobacco smoke. PROCEDURE: Cats were placed into a barometric plethysmograph with an internal volume of 38 L, and air flow was recorded at baseline and after carbachol (concentrations 0.005, 0.01, 0.02, 0.05, 0.1, and 0.2%) was introduced into the chamber. A dose-response curve was generated for several flow-derived measurements, and airway reactivity was determined by interpolation of the dose-response curve for enhanced pause. RESULTS: Peak inspiratory and expiratory flows increased significantly, but respiratory rate, inspiratory and expiratory times, relaxation time, and tidal volume did not differ significantly from baseline values. Flow-derived measurements (pause, enhanced pause, and end-expiratory pause) increased significantly at carbachol concentrations > 0.02%. Baseline measurements did not correlate with indices of airway reactivity. CONCLUSIONS AND CLINICAL RELEVANCE: Airway reactivity can be measured by use of BWBP, which is noninvasive. Airway reactivity was highly variable among cats and was not a function of baseline airway caliber, suggesting that other intrinsic mechanisms may be important.

Animals↗
PubMed1998

Adrenal insufficiency in a neonatal foal.

A 3-day-old female Pinto was admitted with profuse watery diarrhea and severe hypovolemic shock. After 1 week of intensive care, the foal developed seizures associated with profound serum electrolyte abnormalities suggestive of hypoadrenocorticism. Treatment with prednisone and isotonic saline (0.9% NaCl) solution led to prompt clinical response. Premature withdrawal of prednisone resulted in relapse of clinical signs. A diagnosis of adrenal insufficiency was made on the basis of clinical signs, electrolyte abnormalities, low baseline cortisol concentration, and lack of response to administration of exogenous adrenocorticotropin. Two months later, adrenocortical function was normal and the foal was doing well clinically. Clinical signs of acute adrenal insufficiency in neonatal foals can be confused with other conditions, such as septicemia, enteritis, and ruptured urinary bladder. A persistently low serum sodium-to-potassium ratio associated with CNS malfunction should warrant investigation of adrenal gland function. Acute hypoadrenocorticism in foals may be reversible.

Adrenal Cortex↗
PubMed1998

Association between bronchoalveolar lavage cytologic features and airway reactivity in horses with a history of exercise intolerance.

OBJECTIVE: To correlate indices of airway reactivity to bronchoalveolar lavage (BAL) fluid cytologic features in horses with a recent decline in exercise tolerance. ANIMALS: 20 actively working horses from 2 to 24 years old. PROCEDURE: Bronchoalveolar lavage fluid samples were obtained and analyzed. Forced oscillatory mechanics (1-7 Hz) technique was used for measurements of total respiratory system resistance (RRS), compliance (CRS), and resonant frequency (fres). Changes in RRS (1 Hz) during histamine challenge were used to generate histamine dose-response curves, from which the provocative concentrations that evoked a 75 or 100% increase in baseline RRS (PCRRS75 and PCRRS 100, respectively) were determined. Age, sex, baseline lung mechanics, and BAL cytologic findings were correlated with PCRRS75 and PCRRS100. RESULTS: No horse of the study had clinical signs or history of obstructive pulmonary disease or increased percentage (> 7%) of neutrophils in bronchoalveolar lavage fluid samples. Mean (+/- SEM) RRS, CRS, and fres were 0.67 +/- 0.06 cm of H2O/L/s, 0.52 +/- 0.04 L/cm H2O, and 2.46 +/- 0.02 Hz, respectively. There was no correlation between age or sex, and RRS, CRS, fres, PCRRS75, or PCRRS100. There was a significant correlation (rs = -0.78, P < 0.001) between percentage of BAL fluid mast cells and PCRRS75 or PCRRS100, but correlation with other cell types and indices of airway reactivity were not observed. CONCLUSION: The strong association between mast cell percentage in BAL fluid and airway reactivity in this group suggests that mast cell products may contribute to bronchospasm, airway wall thickening, and/or loss of elastic recoil, which underlie airway hyperreactivity. Alternatively, mast cells may contribute to nonspecific airway reactivity in horses through unknown mechanisms.

Animals↗
PubMed1997

Techniques for sampling the respiratory tract of horses.

Field diagnostic tests for respiratory diseases are constantly evolving. With each new application, equine patients with sinusitis, acute and chronic bacterial and fungal pneumonia SAID, chronic obstructive pulmonary disease, pleuropneumonia or poor performance are managed with greater proficiency. All of these problems can be investigated adequately in the field. This article is a guide to sampling techniques relevant to the ambulatory clinician.

Ambulatory Care↗
PubMed1997

Inhaled medications and bronchodilator usage in the horse.

The advantages of aerosol medications include the direct, topical application to the target organ (airways); rapid effect; and low systemic availability. There are now more efficient methods for aerosol delivery that facilitate the use of increasingly sophisticated aerosol drugs. This article reviews the principles of aerosol deposition and the pharmacology of current medications.

Administration, Inhalation↗