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Biomedical subjects

H McAllister

Publications and source records attributed to H McAllister.

At least 19 recordsLinked to original sources
PubMed2004

Magnetic resonance imaging in the diagnosis and surgical management of sacral osteochondrosis in a mastiff dog.

The clinical, radiographic, magnetic resonance imaging (MRI), surgical and pathological findings related to an osteochondral lesion of the sacrum in a mastiff dog are described. The dog showed chronic signs of pain in its pelvic limbs. Radiography revealed a triangular mineralised opacity at the craniodorsal aspect of the sacrum consistent with sacral osteochondrosis. A T2-weighted spin-echo MRI revealed dorsal and lateral compression of the cauda equina. The osteochondral fragment was removed via a dorsal laminectomy, and the clinical signs resolved. Histological abnormalities in the fragment were consistent with a diagnosis of osteochondrosis.

Animals↗
PubMed2004

Topography of the gastro-oesophageal junction in the dog revisited: possible clinical implications.

The topographical anatomy of the gastro-oesophageal junction was evaluated in six Greyhounds and six Beagles with particular emphasis on the inter-relationship of anatomic structures and landmarks. Significant variation existed between individuals, and a standard topography could not be identified. It was not possible to document the consistent presence of an intra-abdominal oesophagus in either breed examined; in the majority of cases the oesophagus was contained entirely within the thoracic cavity such that no portion of the oesophagus could be subject to abdominal pressures. This has implications for understanding the pathogenesis of hiatal hernia associated gastro-oesophageal reflux disease.

Animals↗
PubMed2003

Kinking of endotracheal tubes during maxima flexion of the atlanto-occipital joint in dogs.

Endotracheal tubes manufactured from red rubber and polyvinyl chloride (PVC) were compared, using radiographic techniques, in dog cadavers, under in vitro conditions and in anaesthetised dogs (in vivo study). All endotracheal tubes were radiographed in 'neutral' and flexed positions and the percentage reduction in the ventrodorsal radiographical diameter of the tube was calculated. The red rubber tubes kinked completely in 40 per cent of the cadavers, 75 per cent of the in vitro study and 40 per cent of anaesthetised dogs. The PVC tubes kinked completely in only one case (in vivo study). However, these tubes had a mean reduction in diameter of 15 per cent in the dog cadaver study, 19 per cent in the in vitro study and 26 per cent in the in vivo study. During procedures in which the trachea is intubated and the atlanto-occipital joint of the patient must be flexed, PVC endotracheal tubes may be less prone to kinking than red rubber tubes.

Airway Obstruction↗
PubMed2002

Evaluation of peripheral lymphoreticular biopsy techniques and their clinical side effects in sheep.

Tissue samples were collected postmortem from 126 sheep at five lymphoreticular sites by different techniques. The three most successful combinations of sites and techniques were: the third eyelids, using a forceps and scissors, which provided a mean (se) of 5.32 (0.70) lymphoid follicles per 5 microm tissue section, a mandibular lymph node, using a Biopty gun, which gave 1.19 (0.26) lymphoid follicles per 5 microm tissue section, and tonsil, using a biopsy forceps, which gave 1.14 (0.27) lymphoid follicles per 5 microm tissue section. These three techniques were repeated once a month for five months on five sheep under general anaesthesia, and their clinical effects were compared with five control sheep which were restrained and anaesthetised in the same way but from which no biopsies were taken. Most lymphoid follicles (3.47 [0.58] per 5 pm tissue section) were obtained by using the third eyelid biopsy technique. There were no clinical side effects associated with the biopsy procedure. There were increases in the plasma concentration of cortisol in all the animals, suggesting that the restraint and anaesthesia were more stressful than the biopsy procedure.

Animals↗
PubMed2002

Cellophane banding of congenital intrahepatic portosystemic shunts in two Irish wolfhounds.

Two three-month-old, male Irish wolfhound siblings were diagnosed with breed-typical left divisional congenital intrahepatic portosystemic shunts consistent with patent ductus venosus. The shunts were amenable to surgical dissection at a posthepatic location. Both dogs had cellophane banding for shunt attenuation. One dog was euthanased after developing post-ligation neurological dysfunction, which was refractory to treatment. The other dog survived and demonstrated shunt attenuation. Successful surgical management using cellophane banding of a patent ductus venosus has not been previously described in a large-breed dog.

Animals↗
PubMed2001

Chromatographic methods for product-profile analysis and isolation of oligosaccharides produced by heparinase-catalyzed depolymerization of heparin.

A two-dimensional chromatography method for monitoring the formation of oligosaccharides produced by heparinase-catalyzed depolymerization of heparin is reported. In the first step of the two-dimensional method, the depolymerized heparin is size-fractionated by high-performance gel permeation chromatography (HPGPC). The size-uniform fractions are then separated on the basis of charge by strong anion-exchange (SAX) HPLC on a high resolution CarboPac PA1 column. To demonstrate application of the two-dimensional product-profile analysis method, data are presented for the heparinase I-catalyzed depolymerization of heparin in the absence and presence of histamine, a ligand that binds site-specifically to heparin. Results from the two-dimensional analysis indicate that histamine alters the extent of depolymerization and the product-profiles for the tetrasaccharide and hexasaccharide fractions. The use of CarboPac PA1 columns for the semi-preparative scale separation of oligosaccharides in size-uniform fractions isolated from depolymerized heparin by low-pressure (gravity flow) GPC is also reported. The semi-preparative scale CarboPac PA1 column gives high resolution and excellent reproducibility after repeated use over an extended period of time, making it possible to reliably combine fractions from multiple separations. The oligosaccharides are eluted from the CarboPac PA1 column with a NaCl gradient at relatively low pH (3 or 7) where they are stable. An efficient two-step procedure is described for desalting oligosaccharides separated

Animals↗
PubMed2001

Para-aural abscessation following traumatic ear canal separation in a dog.

Traumatic ear canal separation is rare in animals, with only eight dogs and one cat reported with the condition in the English language literature. Para-aural abscessation occurred in six of these nine animals. Diagnosis was made on otoscopic observation of a shortened, abruptly ending external ear canal that was free from advanced disease. Radiographs in those cases which have been described showed a disruption of the normal air opacity of the affected ear canal. Drainage, by creating a separate opening for the horizontal ear canal, or total ear canal ablation and lateral bulla osteotomy (TECA/LBO), have led to resolution of the clinical signs. This report adds a further case to the literature in which TECA/LBO was employed successfully.

Abscess↗
PubMed2001

Barrier pressure at the gastroesophageal junction in anesthetized dogs.

OBJECTIVE: To evaluate the effect of body position on barrier pressure at the gastroesophageal junction in anesthetized Greyhounds and to assess alterations in barrier pressure following gastropexy. ANIMALS: 8 adult Greyhounds. PROCEDURE: Barrier pressure at the gastroesophageal junction was measured by fast (1 cm/s) and slow (1 cm/10 s) withdrawal of a subminiature strain gauge transducer through the gastroesophageal junction in 8 anesthetized dogs. The effect of body position was measured. Each dog then was placed in right-lateral recumbency, and gastropexy was performed in the left flank. Additional measurements were obtained 1, 5, 10, 20, and 30 minutes after gastropexy. RESULTS: Barrier pressure for dogs positioned in sternal recumbency (mean +/- SEM, 1.1 +/- 0.53 mm Hg) was significantly less than for dogs positioned in right lateral or left lateral recumbency. Following gastropexy, there was a steady increase in barrier pressure. Thirty minutes after gastropexy, barrier pressure was significantly higher (13.36 +/- 3.46 mm Hg), compared with the value before surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Barrier pressure in anesthetized dogs is highly variable and influenced by body position. This is most likely the result of anatomic interrelationships between the diaphragm, stomach, and terminal portion of the esophagus. Gastropexy also increases barrier pressure in the immediate postoperative period, which may be clinically relevant in terms of understanding how resolution of gastroesophageal reflux disease associated with hiatal hernia may be affected by gastropexy combined with hernia reduction.

Abdominal Muscles↗
PubMed2000

Intra-atrial rhabdomyoma causing chylopericardium and right-sided congestive heart failure in a dog.

A six-year-old Staffordshire bull terrier had a four-week history of progressive lethargy, ascites and exercise intolerance. A mass 3 cm in diameter obliterating the right atrial lumen was detected by echocardiographic examination. There were lactescent pericardial and serosanguineous pleural effusions. Histological and immunochemical examinations showed that the mass was a primary rhabdomyoma.

Animals↗
PubMed2000

Interaction of heparin with a synthetic pentadecapeptide from the C-terminal heparin-binding domain of fibronectin.

The synthetic pentadecapeptide FN-C/H II (KNNQKSEPLIGRKKT-NH(2)) has the sequence of the carboxy-terminal heparin-binding domain of module III(14) of fibronectin. Interaction of FN-C/H II with bovine lung heparin has been studied by (1)H and (23)Na NMR spectroscopy and by heparin affinity chromatography. FN-C/H II binds to heparin from pD <2 up to pD approximately 10; at higher pD, the binding decreases as the lysine side-chain ammonium groups are titrated. Na(+) counterions are displaced from the counterion condensation volume that surrounds sodium heparinate by FN-C/H II, which provides direct evidence that the binding involves electrostatic interactions. The pK(A) values for each of the five ammonium groups of FN-C/H II increase upon binding to heparin which, together with chemical shift data, indicates that the binding involves both delocalized and direct electrostatic interactions between ammonium groups of FN-C/H II and carboxylate and/or sulfate groups of heparin. NMR data also provide evidence for the direct interaction of the guanidinium group of the arginine side chain with anionic sites on heparin. The affinity of heparin for FN-C/H II and for 13 analogue peptides in which lysine and arginine residues were systematically substituted with alanine increases as the number of basic residues increases. The relative contribution of each lysine and arginine to the affinity of heparin for FN-C/H II is R(12) > K(13) > K(14) > K(1) > K(5). Nuclear Overhauser enhancement (NOE) data indicate that, while FN-C/H II is largely unstructured in aqueous solution, the bound peptide interconverts among overlapping, turn-like conformations over the L(9) - T(15) segment of the peptide. NOE data for the interaction of FN-C/H II with a heparin-derived hexasaccharide, together with the number of Na(+) ions displaced from heparin by FN-C/H II as determined by (23)Na NMR, indicates that the peptide binds to a hexasaccharide segment of heparin. Identical NMR and heparin affinity chromatography results were obtained for the interaction of FN-C/H II and its D-amino acid analogue peptide with heparin, which is of interest for the potential use of peptides as therapeutic agents for diseases in which cell adhesion plays a critical role.

Amino Acid Sequence↗
PubMed2000

Primary pulmonary artery leiomyosarcoma in an adult dog.

A 7-year-old neutered female English Setter presented with syncope, anemia, and weight loss. Clinical examination revealed a systolic murmur and echocardiography demonstrated a mass on the pulmonic valve. Postmortem examination confirmed the presence of a pulmonic valve mass that extended along the pulmonary trunk and into the left pulmonary artery. Multiple pale nodules were observed in the right lung. Microscopic examinations of the pulmonary artery mass and the lung nodules revealed a pleomorphic population of spindle cells often arranged in broad bands containing strap-like nuclei and eosinophilic cytoplasm devoid of cross striations. The neoplastic cells expressed vimentin and alpha-smooth muscle actin but did not express desmin, CD31, factor VIII, or S100. The presentation, histological features, immunocytochemical profiles, and behavior of this tumor were indicative of a primary pulmonary artery leiomyosarcoma with lung metastasis.

Animals↗
PubMed1999

A simple, rapid and sensitive semimicro method for the measurement of cyanide in blood.

Conventional methods do not meet the clinical need for rapid cyanide measurements. We report a procedure which can provide a result in 10 min. It should be of particular interest to laboratories serving cardiac or renal units which use the hypotensive agent sodium nitroprusside, and burns units to which fire victims may be admitted suffering the effects of HCN from inhaled smoke. A sample of blood (100 microL) is mixed with H3PO4, containing a surfactant, and the HCN is trapped in an alkaline mixture of 1,2-dinitrobenzene and 4-nitrobenzaldehyde in 2-methoxyethanol. The catalytic action of cyanide, which produces purple 2-nitrophenylhydroxylamine, is stopped with acetone after 6 min. The absorbance measured at 560 nm shows a linear relationship with the cyanide concentration, but the slope varies with the ambient temperature. Since KCN added to both 50 mmol/L NaOH and blood gives similar assay results, any inaccuracy arising from changes in temperature can be avoided by running standards at the same time as the blood sample.

Clinical Laboratory Techniques↗
PubMed1997

Cervico-thoracic vertebral osteomyelitis in 14 calves.

Fourteen cases of cervico-thoracic (C-T) vertebral osteomyelitis in calves were investigated over a 6 year period. The onset of clinical signs was between 2 and 9 weeks of age. There was no breed or sex predisposition. The clinical history prior to referral extended from 5 days to 8 weeks (mean 20 days). The most common clinical presentation was difficulty in rising with a tendency to knuckle or kneel on the forelimbs which displayed hypotonia and hyporeflexia. In over half the cases pain could be elicited on manipulation of the neck. The lesion in all cases involved one or more of the vertebrae from C6 to T1. The diagnosis was confirmed by radiology and/or at post mortem. Four animals were discharged after treatment, 10 animals were humanely destroyed. Salmonella dublin was isolated from the vertebral lesion in eight of the 10 calves at post mortem.

Animals↗
PubMed1997

Avulsion of the tibial tuberosity in a litter of greyhound puppies.

Avulsion of the tibial tuberosity was diagnosed in six of seven greyhound littermates aged five and a half months. The puppies showed hindlimb lameness of varying severity. Radiological assessment of affected stifle joints revealed partial or complete avulsion of the tibial tuberosities. In four puppies the lesions were bilateral. Euthanasia of the two most severely affected puppies was performed; the changes observed on histopathological examination of their cranioproximal tibiae suggested that the underlying lesion was that of osteochondrosis. A hereditary predisposition in greyhounds to osteochondrosis of the physis between the apophysis and the cranioproximal tibial diaphysis is postulated.

Animals↗
PubMed1992

Transmission of retroviruses from seronegative donors by transfusion during cardiac surgery. A multicenter study of HIV-1 and HTLV-I/II infections.

OBJECTIVE: To evaluate the effectiveness of serologic testing of blood donors for human immunodeficiency virus type 1 (HIV-1) and human T-cell lymphotropic virus types I and II (HTLV-I/II) infections and to estimate the risk for transmission of HIV-1 and HTLV-I/II by transfusion of seronegative blood from screened donors. DESIGN: A prospective multicenter cohort study of cardiac surgery patients who received multiple transfusions between 1985 and 1991. SETTING: Cardiac surgery services of three large tertiary care hospitals. PATIENTS: The study included 11,532 patients in three hospitals who had cardiovascular surgery. MEASUREMENTS: Incident HIV-1 and HTLV-I or HTLV-II infection. RESULTS: We detected two new HIV-1 infections among patients transfused with 120,312 units of blood components from seronegative donors. In each case a donor was detected on follow-up who had seroconverted since the donation. The HIV-1 infection rate was 0.0017% with an upper limit of the 95% CI of 0.0053%. Before donor screening for HTLV-I, transfusion of 51,026 units resulted in two HTLV-I infections (0.0039%) and four HTLV-II infections (0.0078%). After HTLV-I screening was instituted, one recipient was infected with HTLV-II among participants exposed to 69,272 units, a rate of 0.0014%. A corresponding HTLV-I/II-infected donor was found for this patient. CONCLUSION: Serologic screening of donors for antibodies to HIV-1 and HTLV-I coupled with exclusion of donors from groups having a relatively high risk for infection has led to a low incidence of transfusion-transmitted HIV-1 and HTLV-I/II infection in the United States. A small risk remains, however, despite these measures. We estimate the residual risk for HIV-1 and HTLV-II infection from transfusion of screened blood during the time of this study to be about 1 in 60,000 units.

Aged↗