Wear testing of a canine hip resurfacing implant that uses highly cross-linked polyethylene

Hip resurfacing offers advantages for young, active patients afflicted with hip osteoarthritis and may also be a beneficial treatment for adult canines. Conventional hip resurfacing uses metal-on-metal bearings to preserve bone stock, but it may be feasible to use metal-on-polyethylene bearings to reduce metal wear debris while still preserving bone. This study characterized the short-term wear behavior of a novel hip resurfacing implant for canines that uses a 1.5 mm thick liner of highly cross-linked polyethylene in the acetabular component. This implant was tested in an orbital bearing machine that simulated canine gait for 1.1 million cycles. Wear of the liner was evaluated using gravimetric analysis and by measuring wear depth with an optical scanner. The liners had a steady-state mass wear rate of 0.99 ± 0.17 mg per million cycles and an average wear depth in the central liner region of 0.028 mm. No liners, shells, or femoral heads had any catastrophic failure due to yielding or fracture. These results suggest that the thin liners will not prematurely crack after implantation in canines. This is the first hip resurfacing device developed for canines, and this study is the first to characterize the in vitro wear of highly cross-linked polyethylene liners in a hip resurfacing implant. The canine implant developed in this study may be an attractive treatment option for canines afflicted with hip osteoarthritis, and since canines are the preferred animal model for human hip replacement, this implant can support the development of metal-on-polyethylene hip resurfacing technology for human patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1196-1205, 2018.

Altered gene expression in blood and sputum in COPD frequent exacerbators in the ECLIPSE cohort

Patients with chronic obstructive pulmonary disease (COPD) who are defined as frequent exacerbators suffer with 2 or more exacerbations every year. The molecular mechanisms responsible for this phenotype are poorly understood. We investigated gene expression profile patterns associated with frequent exacerbations in sputum and blood cells in a well-characterised cohort. Samples from subjects from the ECLIPSE COPD cohort were used; sputum and blood samples from 138 subjects were used for microarray gene expression analysis, while blood samples from 438 subjects were used for polymerase chain reaction (PCR) testing. Using microarray, 150 genes were differentially expressed in blood (>±1.5 fold change, p≤0.01) between frequent compared to non-exacerbators. In sputum cells, only 6 genes were differentially expressed. The differentially regulated genes in blood included downregulation of those involved in lymphocyte signalling and upregulation of pro-apoptotic signalling genes. Multivariate analysis of the microarray data followed by confirmatory PCR analysis identified 3 genes that predicted frequent exacerbations; B3GNT, LAF4 and ARHGEF10. The sensitivity and specificity of these 3 genes to predict the frequent exacerbator phenotype was 88% and 33% respectively. There are alterations in systemic immune function associated with frequent exacerbations; down-regulation of lymphocyte function and a shift towards pro-apoptosis mechanisms are apparent in patients with frequent exacerbations.

Painful decisions for senior pets

Osteoarthritis and cancer are the inevitable consequences of aging and significantly contribute to the cause of death in cats and dogs. Managing the pain associated with these disease states is the veterinarian’s mandate. Many treatment modalities and agents are available for patient management; however, it is only with an understanding of disease neurobiology and a mechanism-based approach to problem diagnosis that the clinician can offer patients an optimal quality of life based on evidence-based best medicine. When treating pain, knowledge is still our best weapon.

Induced sputum genes associated with spirometric and radiological disease severity in COPD ex-smokers

BACKGROUND

Induced sputum is used to sample inflammatory cells, predominantly neutrophils and macrophages, from the airways of COPD patients. The author's aim was to identify candidate genes associated with the degree of airflow obstruction and the extent of emphysema by expression profiling, and then to confirm these findings for selected candidates using PCR and protein analysis.

METHODS

Two sputum studies were performed in Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2-4 COPD ex-smokers from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) cohort. First, gene array profiling at baseline in samples from 148 patients. The findings were replicated in a separate population of 176 patients using real-time PCR. The findings for one selected gene IL-18R were further analysed using immunohistochemistry in lung tissue and induced sputum from patients outside the ECLIPSE cohort.

RESULTS

Gene expression profiling revealed changes in 277 genes associated with GOLD stage 2 versus 3 and 4, and 198 genes with changes associated with the degree of emphysema (p < 0.01 for each gene). Twelve of these candidate genes were analysed by PCR in the replication cohort, with significant changes (p < 0.05) observed for 11 genes. IL-18R protein expression was higher on alveolar macrophages in lung tissue of COPD patients (mean 23.2%) compared to controls (mean ex-smokers 2% and non-smokers 2.5%).

CONCLUSION

Gene expression profiling in sputum cells identified candidate genes that may play roles in molecular mechanisms associated with COPD. The replication by PCR and protein in different studies confirms these findings, and highlights a potential role for IL-18R upregulation in severe COPD.

Broncho-oesophageal fistula in two dogs

Two clinical cases of broncho-oesophageal fistula in the dog are presented. While both cases illustrate the value of oesophagoscopy as a diagnostic tool, one case depicts the complications which may be associated with positive contrast oesophagography. These two cases support previous observations that broncho-oesophageal fistulae are frequently of foreign body aetiology and usually extend from the caudal oesophagus, via the pleural space, to the caudal or middle right lung lobes.

Gastrointestinal tract perforation in dogs treated with a selective cyclooxygenase-2 inhibitor: 29 cases (2002-2003)

OBJECTIVE

To identify factors associated with gastrointestinal tract perforation in dogs being treated with a selective cyclooxygenase-2 (COX-2) inhibitor (deracoxib).

DESIGN

Retrospective study.

ANIMALS

29 dogs.

PROCEDURE

The Novartis Animal Health pharmacovigilance database was searched for records of dogs treated with deracoxib in which gastrointestinal tract perforation was documented. Results-16 of the 29 (55%) dogs had received deracoxib at a dosage higher than that approved by the FDA for the particular indication being treated, with 25 (86%) dogs having received deracoxib at a dosage > 2 mg/kg/d (0.9 mg/lb/d). Seventeen (59%) dogs had received at least 1 other nonsteroidal anti-inflammatory drug (NSAID) or a corticosteroid in close temporal association (within 24 hours) with deracoxib administration (ie, immediately before or following). In all, 26 (90%) dogs had received deracoxib at a higher-than-approved dosage or had received at least 1 other NSAID or corticosteroid in close temporal association with deracoxib administration. Twenty dogs died or were euthanatized, and 9 survived.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs with gastrointestinal tract perforation and that had been treated with deracoxib, perforation was most likely attributable to a number of factors. Deracoxib should only be used at approved dosages. Cortico-steroids and other less selective NSAIDs should not be administered in close temporal association with selective COX-2 inhibitors, including deracoxib. Further study is required to define this problem.

Anesthetic effects of ketamine or isoflurane induction prior to isoflurane anesthesia in medetomidine-premedicated dogs

Dogs were given medetomidine (10 microg/kg body weight, intramuscularly) followed in 10 minutes by either ketamine (4 mg/kg body weight, intravenously) or isoflurane mask induction and maintained on isoflurane for 30 minutes. Medetomidine induced lateral recumbency in all dogs. Endotracheal intubation was faster and smoother when dogs were given ketamine than when induced with isoflurane. Analgesia was excellent in all groups. Respiratory depression was more profound when dogs were given ketamine. Recovery quality was smooth and similar among all groups. Medetomidine-premedicated dogs could be induced with either ketamine or isoflurane and maintained on 1.3% isoflurane to achieve good analgesia with smooth recovery from anesthesia.

Effects of preemptive atropine administration on incidence of medetomidine-induced bradycardia in dogs

OBJECTIVE

To determine the cardiorespiratory effects of preemptive atropine administration in dogs sedated with medetomidine.

DESIGN

Randomized crossover trial.

ANIMALS

12 healthy adult dogs.

PROCEDURES

Dogs underwent 6 treatments. Each treatment consisted of administration of atropine (0.04 mg/kg [0.018 mg/lb] of body weight, IM) or saline solution (0.9% NaCl, 1 ml, IM) and administration of medetomidine (10, 20, or 40 microg/kg [4.5, 9.1, or 18.2 microg/lb], IM) 10 minutes later. Treatments were administered in random order, with a minimum of 1 week between treatments. Cardiorespiratory effects before and after atropine and medetomidine administration were assessed. Duration of lateral recumbency and quality of sedation and recovery were assessed.

RESULTS

Bradycardia (heart rate < 60 beats/min) was seen in all dogs when saline solution was administered followed by medetomidine, and the dose of medetomidine was not associated with severity or frequency of bradycardia or second-degree heart block. However, a medetomidine dose-dependent increase in mean and diastolic blood pressures was observed, regardless of whether dogs received saline solution or atropine. Preemptive atropine administration effectively prevented bradycardia and second-degree heart block but induced pulsus alternans and hypertension. The protective effects of atropine against bradycardia lasted 50 minutes. Blood gas values were within reference limits during all treatments and were not significantly different from baseline values. Higher doses of medetomidine resulted in a longer duration of lateral recumbency.

CONCLUSIONS AND CLINICAL RELEVANCE

Preemptive administration of atropine in dogs sedated with medetomidine effectively prevents bradycardia for 50 minutes but induces hypertension and pulsus alternans.

Cardiorespiratory responses and plasma cortisol concentrations in dogs treated with medetomidine before undergoing ovariohysterectomy

OBJECTIVE

To evaluate effects of medetomidine on anesthetic dose requirements, cardiorespiratory variables, plasma cortisol concentrations, and behavioral pain scores in dogs undergoing ovariohysterectomy.

DESIGN

Randomized, prospective study.

ANIMALS

12 healthy Walker-type hound dogs.

PROCEDURE

Dogs received medetomidine (40 micrograms/kg [18.2 micrograms/lb] of body weight, i.m.; n = 6) or saline (0.9% NaCl) solution (1 ml, i.m.; 6) prior to anesthesia induction with thiopental; thiopental dose needed for endotracheal intubation was compared between groups. Ovariohysterectomy was performed during halothane anesthesia. Blood samples were obtained at various times before drug administration until 300 minutes after extubation. Various physiologic measurements and end-tidal halothane concentrations were recorded.

RESULTS

In medetomidine-treated dogs, heart rate was significantly lower than in controls, and blood pressure did not change significantly from baseline. Plasma cortisol concentrations did not increase significantly until 60 minutes after extubation in medetomidine-treated dogs, whereas values in control dogs were increased from time of surgery until the end of the recording period. Control dogs had higher pain scores than treated dogs from extubation until the end of the recording period.

CONCLUSION AND CLINICAL RELEVANCE

Administration of medetomidine reduced dose requirements for thiopental and halothane and provided postoperative analgesia up to 90 minutes after extubation. Dogs undergoing ovariohysterectomy by use of thiopental induction and halothane anesthesia benefit from analgesia induced by medetomidine administered prior to anesthesia induction. Additional analgesia is appropriate 60 minutes after extubation.

The effects of ovariohysterectomy plus different combinations of halothane anaesthesia and butorphanol analgesia on behaviour in the bitch

One hundred and sixty-six behaviours were identified as possible indices of post-operative pain-induced distress in the bitch. These were assessed in bitches after treatment with different combinations of halothane and butorphanol in the absence of surgery and following ovariohysterectomy under halothane anaesthesia with or without butorphanol analgesia given at different stages during the operation. Behaviour was monitored while the bitches were alone (non-interactive) and when routinely examined and handled prior to blood sampling (interactive). Seventy-six of the 166 behaviours occurred so infrequently (less than two occurrences per hour) as to be of no value as indices. Non-interactive behaviours associated with surgery were a decrease in normal speed cage circling and an increase in drawing the rear limbs up in the pike position. The infrequent non-interactive behaviours of incision licking, vomiting and flank gazing were considered to be expressions of pain caused by ovariohysterectomy. During the post-surgical period, bitches given analgesic moved less frequently than those not receiving analgesic. Vocalisation was associated with dysphoria of analgesia rather than pain-induced distress. The behaviour of bitches after ovariohysterectomy suggests that this is a painful procedure which warrants analgesia.

Sedative and cardiorespiratory effects of medetomidine, medetomidine-butorphanol, and medetomidine-ketamine in dogs

OBJECTIVE

To determine sedative and cardiorespiratory effects of i.m. administration of medetomidine alone and in combination with butorphanol or ketamine in dogs.

DESIGN

Randomized, crossover study.

ANIMALS

6 healthy adult dogs.

PROCEDURES

Dogs were given medetomidine alone (30 micrograms/kg [13.6 micrograms/lb] of body weight, i.m.), a combination of medetomidine (30 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or a combination of medetomidine (30 micrograms/kg, i.m.) and ketamine (3 mg/kg [1.36 mg/lb], i.m.). Treatments were administered in random order with a minimum of 1 week between treatments. Glycopyrrolate was given at the same time. Atipamezole (150 micrograms/kg [68 micrograms/lb], i.m.) was given 40 minutes after administration of medetomidine.

RESULTS

All but 1 dog (given medetomidine alone) assumed lateral recumbency within 6 minutes after drug administration. Endotracheal intubation was significantly more difficult when dogs were given medetomidine alone than when given medetomidine and butorphanol. At all evaluation times, percentages of dogs with positive responses to tail clamping or to needle pricks in the cervical region, shoulder region, abdominal region, or hindquarters were not significantly different among drug treatments. The Paco2 was significantly higher and the arterial pH and Pao2 were significantly lower when dogs were given medetomidine and butorphanol or medetomidine and ketamine than when they were given medetomidine alone. Recovery quality following atipamezole administration was unsatisfactory in 1 dog when given medetomidine and ketamine.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that a combination of medetomidine with butorphanol or ketamine resulted in more reliable and uniform sedation in dogs than did medetomidine alone.

Changes in plasma cortisol concentrations in bitches in response to different combinations of halothane and butorphanol, with or without ovariohysterectomy

Changes in plasma cortisol concentrations were assessed in bitches in response to nine treatments: control, anaesthesia, analgesia, analgesia followed by anaesthesia, anaesthesia followed by analgesia at intubation, anaesthesia followed by analgesia at extubation, anaesthesia plus surgery, analgesia followed by anaesthesia plus surgery, and anaesthesia plus surgery followed by analgesia. The anaesthetic was halothane, the analgesic was butorphanol (0.4 mg kg(-1)) and the surgery was ovariohysterectomy. Blood samples, for plasma cortisol assays, were taken regularly from before treatment for five hours and then again after 24 hours. A small transient rise in plasma cortisol concentration in the control group was attributed to mild distress associated with novel experiences. A more pronounced and protracted rise in cortisol concentration in the analgesia group was ascribed to a dysphoric state of bitches under the influence of the agonist-antagonist butorphanol. Halothane anaesthesia alone resulted in no change in plasma cortisol concentration. When butorphanol was given after anaesthesia was induced or while the animal was still under the influence of anaesthesia (immediately after tracheal extubation), there was no immediate rise in plasma cortisol concentration and low concentrations were maintained for up to 60 minutes after halothane withdrawal. A marked rise in plasma cortisol concentration, which was sustained above pretreatment values for at least five hours, occurred in all surgery groups. Giving intravenous butorphanol 30 minutes prior to surgery had no effect on the surgically-induced rise in plasma cortisol concentration and no effect on the postsurgical plasma cortisol concentration. In contrast, butorphanol given at extubation did reduce plasma cortisol concentrations during the postsurgical period. These observations did not support the hypothesis that preoperative use of butorphanol would reduce the cortisol response after surgery under halothane anaesthesia.

Mechanisms of action of anti-inflammatory medications used for the treatment of osteoarthritis

Nonsteroidal anti-inflammatory (NSAID) drugs have been used to treat osteoarthritis ever since 1899, when the effects of aspirin were first recognized. Widespread use of these compounds continues despite their recognized potential toxicity, mostly because they are generally effective for palliation of the pain associated with osteoarthritis. The discovery of cyclooxygenase (COX)-1 and COX-2 has sparked interest in development of NSAID that specifically target COX-2, with the hope that such compounds would be associated with a lower incidence of adverse gastrointestinal effects. Other potential methods of avoiding adverse gastrointestinal effects associated with NSAID use include concurrent administration of prostaglandins and use of pure analgesics, such as acetaminophen. The role of nitric oxide in inflammation is an exciting area of research, and addition of nitric oxide-producing moieties to NSAID may prove to be another mechanism of avoiding gastrointestinal toxicity. There is likely to be considerable reward for the development of an NSAID that relieves pain associated with a wide variety of conditions, does not cause gastrointestinal toxicoses, and spares normal cartilage. Whether such a drug exists remains speculative.

Use of carprofen for the treatment of pain and inflammation in dogs

Most studies of nonsteroidal anti-inflammatory drugs (NSAID) do not demonstrate appreciable differences in efficacy. As awareness of the adverse effects associated with NSAID use increases, safety is becoming the primary concern among physicians when selecting NSAID for use by their human patients. However, veterinarians may be less aware of the safety concerns associated with NSAID use. A wide range of NSAID is used to treat human beings with osteoarthrits; however, it is imperative to remember that dogs are especially sensitive to these drugs, and reports of serious, and occasionally fatal, complications are numerous. Carprofen is a propionic acid-derived NSAID that has anti-inflammatory, analgesic, and antipyretic activity. In animals, carprofen is as potent as indomethacina and more potent than aspirin or phenlbutazone, but carprofen appears to be safer than most other NSAID.

Reconstruction of the medial collateral ligament for tarsocrural luxation in the dog: a preliminary study

Seven cases of tarsocrural subluxation/luxation resulting from ruptures of the medial collateral ligament were treated by double prosthetic replacement. The technique was a revision of an earlier described method without the use of metallic implants. Six (100%) of six cases not involving additional joint fractures had excellent clinical results with minimal compromise to range of joint motion. In three (50%) of six cases where braided polyester sutures were implanted as the prosthesis, fistulating tracts developed. Drainage resolved with removal of the suture in each of these three cases, and two of the three proceeded to excellent results after replacing the braided suture with monofilament suture.

Ununited anconeal process: lag-screw fixation

A technique of lag-screw fixation for ununited anconeal process is described, and the results of surgery in eight dogs (on 10 elbows) treated by this technique are presented. Approximation of the process was confirmed postoperatively, and union was confirmed by radiographic followup in six of the 10 forelimbs from two-to-six months after surgery. Four other cases were lost to radiographic follow-up. This report of a limited number of cases suggests encouraging results obtained by lag-screw fixation.

Antebrachial deformities in the dog: treatment with external fixation

The results of 12 dogs with antebrachial deformity treated by ulnar ostectomy, radial osteotomy and external skeletal fixation are presented. Postoperative complications were seen in only one dog; a delayed union requiring placement of autogenous cancellous bone graft at a second surgery to achieve healing. Postoperatively, owners reported limb function was good in almost all cases, although they were less pleased with the cosmetic appearance.

Primary intraosseous fibrosarcoma in a cat

A case of primary intraosseous fibrosarcoma of the left femur in a cat was diagnosed at necropsy following 9 months of managing a fracture of the same bone. Case features were those of probable pathological fracture, fracture repair and ultimate lysis of all but a fragment of the distal femoral epiphysis. Histology revealed closely packed whorls of fibroblasts typical of fibrosarcoma. This neoplasm is rare in the cat.

Changes in plasma cortisol concentrations before, during and after analgesia, anaesthesia and anaesthesia plus ovariohysterectomy in bitches

Plasma cortisol concentrations were determined before, during and after analgesia, anaesthesia and anaesthesia plus ovariohysterectomy in six New Zealand border collie cross bitches. The treatments were: control, analgesia with butorphanol, anaesthesia with thiopentone sodium, halothane and oxygen and anaesthesia plus surgery. In addition, each bitch was given an ACTH challenge. All the bitches showed transient increases in plasma cortisol concentrations and the integrated cortisol responses (calculated as the area under the cortisol curve above the pre-treatment concentration) for 6.25 hours after treatment increased in the order: control, anaesthesia, analgesia, surgery. The control group had increased cortisol concentrations attributable to the excitement from handling. The plasma cortisol concentrations of the group subjected to surgery were greater than the other groups for at least 6.25 hours, with an approximately four-fold increase above pre-treatment values, but they had returned to pre-treatment levels after 24 hours.

Ondansetron versus ondansetron, dexamethasone, and chlorpromazine in the prevention of nausea and vomiting associated with multiple-day cisplatin chemotherapy

PURPOSE

This study is designed to evaluate the effectiveness of ondansetron alone (OND) or in combination with 2 days of dexamethasone and 5 days of chlorpromazine (ODC) in the prevention of emetic episodes in patients receiving multiple-day cisplatin.

PATIENTS AND METHODS

Forty-four patients receiving 20 or 40 mg/m2 of cisplatin daily for 4 to 5 days plus etoposide (VP-16) alone or in combination with bleomycin or ifosfamide were randomized to receive three doses of OND (0.15 mg/kg 30 minutes before and 4 and 8 hours after cisplatin) versus the identical OND regimen plus dexamethasone 8 mg before cisplatin and 4 mg 4 and 8 hours later on days 1 and 2, plus chlorpromazine 50 mg every 4 hours for four doses per day. Patients were chemotherapy-naive, had a Karnofsky performance status > or = 60, and were not receiving nonstudy antiemetics.

RESULTS

Nineteen of 22 patients (86%) on ODC had fewer than three emetic episodes throughout the study period, compared with 10 of 22 (46%) on OND (P = .009), and 55% of patients on ODC had no emetic episodes, compared with 32% on OND (P = .22). The ODC arm had fewer treatment failures (5%) than the OND arm (32%). The mean nausea ratings per visual analog scale were 15.0 for OND and 5.5 for ODC (P = .046). Headache was less frequent with ODC versus OND (14% and 41%, respectively, P = .09).

CONCLUSION

ODC was superior to OND with respect to therapeutic efficacy and decreased headaches. Both OND and ODC were more effective on days 1 and 2, rather than days 4 and 5, suggesting tachyphylaxis, anticipatory nausea, or delayed nausea from the first few days of cisplatin combination chemotherapy.

Corrective osteotomy for bilateral forelimb varus deformities in a working dog

Bilateral varus antebrachial deformity in a 7-month-old working dog was surgically corrected. The deformity was a sequela to premature closure of the distal radial physes after trauma to the forelimbs. Treatment was by ulnectomy and oblique radial osteotomy. Stabilisation of the fractures was maintained by an external fixation device. The treatment was successful and the dog returned to work as a sheep dog.

Allo-implant reconstruction of a femoral fracture following osteomyelitis

A complicated, segmented fracture of the femoral diaphysis in a dog is presented. Complications arose from multiple surgeries and subsequent osteomyelitis. Repair was staged by firstly removing all implants, secondly treating the osteomyelitis with appropriate antibiotics while spanning the cortical-deficient fracture site with a Kirschner external fixator, and finally rigid fixation of the fracture with incorporation of an ethylene oxide-sterilised intercalary cortical allo-implant. Principles of bone grafting are reviewed.

Preparation of IgA-deficient platelets

The IgA-deficient patient presents a difficult transfusion problem, particularly if he or she has previously been immunized and has formed IgA antibodies. Blood components from IgA-deficient donors may be used safely but are often not accessible to transfusion facilities. A satisfactory red cell component may be obtained by standard freezing and washing methods. There is no comparable platelet concentrate that uniformly affords protection against anti-IgA-mediated reactions. A method has been developed for the preparation of an IgA-deficient platelet concentrate by washing with citrate-buffered saline. Platelets prepared in this manner were transfused successfully to an IgA-deficient patient with a history of anaphylaxis related to transfusion. It was further demonstrated that the removal of IgA is enhanced if platelets are washed within 48 hours of collection. When platelets were stored for more than 48 hours, similar washing techniques resulted in significantly higher levels of IgA in the platelets washed with either buffered (p = 0.004) or unbuffered (p = 0.0002) saline. Platelets washed with unbuffered saline (pH 4.5-5.5) contained substantially more IgA than did platelets washed in a similar manner with citrate-buffered saline (pH 6.5-6.8) (p = 0.001).

Delayed redistribution in thallium 201 SPECT myocardial perfusion studies

Stress 201Tl myocardial perfusion studies are useful in differentiating viable, reversibly ischemic from infarcted myocardium. A perfusion defect that shows redistribution 2 to 4 h after 201Tl injection is diagnostic of ischemia, while a fixed defect suggests infarction. However, occasional patients with a fixed defect at 4 h have redistribution at 24 h. This study evaluates the frequency and significance of this delayed redistribution with SPECT 201Tl. Patients with either no or incomplete redistribution at 4 h had repeat imaging 18 to 48 h later. Delayed redistribution was seen in 8/26 (31 percent). Four had incomplete and four had no redistribution at 4 h. Delayed redistribution with SPECT 201Tl is more common than generally appreciated, and we recommend delayed images in patients with fixed perfusion defects or incomplete redistribution at 4-h imaging, particularly in patients with previous infarctions for whom a revascularization procedure is being considered.

Observations on the repair of distal radial osteotomies in the dog by double hook plates

Distal radial osteotomies in the dog repaired with a double hook plate achieved early return to full function. All dogs in this study reached and maintained the desired clinical evaluation score of grade four by the third postoperative week. The average loss of total range of carpal joint motion was 36 degrees. The double hook plate provides stable fixation and can be applied with three point fixation to a bone segment as short as 12 mm.

Combined Kirschner-Ehmer device and dorsal spinal plate fixation technique for caudal lumbar vertebral fractures in dogs

A new surgical technique was developed for the fixation of caudal lumbar vertebral fractures in dogs. The technique provides optimal stabilization, can be used in combination with dorsal decompression, and does not require an intact spinous process on the fractured vertebra or attachment of the fixation devices to the fractured vertebra. The fixation consists of a Kirschner-Ehmer device and dorsal spinal plates. After fracture healing, only mild sedation of the dog is needed to allow removal of the external hardware used in the fixation. The technique, its indications, and its use in 5 cases are described.

Immunoglobulin A (IgA) levels in blood products and plasma derivatives

Both anaphylactic and anaphylactoid reactions to transfused blood products and plasma derivatives have occurred in IgA-deficient patients with antibodies to IgA. This study reports the concentration of IgA in various blood products to assist in the development of treatment protocols for IgA-deficient patients. Five types of blood products and seven types of plasma derivatives were tested for the presence of IgA using a semiquantitative hemagglutination inhibition method. The concentration of lgA was measured by radial immunodiffusion and enzyme-linked immunosorbent assay techniques. Blood products which consistently contained IgA less than 0.05 mg/dL(the present definition for IgA deficiency used by the American Red Cross Rare Donor Registry) were from IgA-deficient donors, deglycerolized red blood cells (RBCs) prepared with an extra wash cycle, and RBCs washed using a total volume of approximately 1300 mL of 0.9 percent sodium chloride.

Persistent hoarseness after surgical removal of vocal cord lesions

Surgical intervention to remove vocal cord lesions usually results in normal vocal cord quality postoperatively. However, some patients exhibit persistent hoarseness after surgery, and often they are referred to a speech pathologist for vocal rehabilitation. In this study, factors were identified in the case histories, surgical management, and behavior during voice rest of patients who experienced persistent hoarseness postoperatively. Eight of ten adult subjects were interviewed and their voices were tape-recorded before and after surgery and were determined to be hoarse postoperatively. Cumulative medical history was the only significant factor that related to persistent hoarseness. Medical histories of disease or infection affecting the respiratory tract were among the specific factors that were identified. Results indicate that patients with these medical factors should be counseled about the risk of persistent hoarseness after surgery.

Pseudoischemic "false positive" S-T segment changes induced by hyperventilation in patients with mitral valve prolapse

Hyperventilation-induced S-T segment changes that simulate myocardial ischemia have previously been noted, but the origin of this electrocardiographic finding has never been defined. To investigate further the basis for this response, the records were reviewed of 1,678 consecutive patients who underwent forced hyperventilation for 90 seconds and treadmill exercise testing. Twenty-eight patients (1.7 percent) were identified in whom hyperventilation resulted in ischemic-appearing S-T segment changes, and follow-up was possible in 21 (17 women, 4 men). Of the 21 patients, 16 (76 percent), including 15 (88 percent) of the 17 women, had evidence of mitral valve prolapse, 6 on auscultation alone, 2 on echocardiography alone and 6 with a combination of studies. Ten of the 21 patients had a negative exercise test; of the 11 patients who had a positive exercise test, only 1 had angiographic evidence of coronary arterial narrowing. The finding of ischemic-appearing S-T segment changes in response to forced hyperventilation has a high predictive value for the presence of mitral valve prolapse, particularly in women. The possible association of autonomic factors and mitral valve prolapse in the pathogenesis of an abnormal response to hyperventilation is discussed.

Mahaim and James fibers as a basis for a unique variety of ventricular preexcitation

This report concerns pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast. Electrocardiograms revealed predominantly normal sinus rhythm with a normal P-R interval and narrow QRS complex. Episodes of sinus rhythm, short P-R interval and QRS widening (with delta wave) were also recorded. During preexcitation QS complexes were noted in leads II, III, aVF, V1 and V4 to V6. Delta waves were negative in leads II, III, aVF and V1 isoelectric in leads V4 to V6 and positive only in leads I, aVL, V2 and V3. This case thus defies classification into any known variety of preexcitation. Complete serial sections, cut through the entire conduction system and both atrioventricular (A-V) rims, totaled 18,600 sections. These revealed no bundle of Kent. Instead, Mahaim fibers histologically identified as His bundle tissue gave off from the A-V bundle to both the right and the left sides of the septum associated with the normal fibers of James. This case reveals that (1) fibers of James can bypass the A-V node, (2) fibers of Mahaim can conduct, and (3) there are types of preexcitation in addition to types A and B.