Cervical vertebral canal endoscopy in the horse: intra- and post operative observations

REASONS FOR PERFORMING STUDY

Despite modern medical diagnostic imaging, it is not possible to identify reliably the exact location of spinal cord compression in horses with cervical vertebral stenotic myelopathy (CVSM). Vertebral canal endoscopy has been successfully used in man and a technique for cervical vertebral canal endoscopy (CVCE) has been described in equine cadavers.

OBJECTIVE

To determine the feasibility and safety of CVCE in healthy mature horses.

METHODS

Six healthy mature horses were anaesthetised. A flexible videoendoscope was subsequently introduced via the atlanto-occipital space into the epidural space (epiduroscopy, Horses 1-3) or the subarachnoid space (myeloscopy, Horses 4-6) and advanced to the 8th cervical nerve. Neurological examinations were performed after surgery and lumbosacral cerebrospinal fluid (CSF) analysed in horses that had undergone myeloscopy.

RESULTS

All procedures were completed successfully and all horses recovered from anaesthesia. Anatomical structures in the epidural space (including the dura mater, nerve roots, fat and blood vessels) and subarachnoid space (including the spinal cord, blood vessels, arachnoid trabeculations, nerve roots and the external branch of the accessory nerve) were identified. During epiduroscopy, a significant increase in mean arterial pressure was recognised, when repeated injections of electrolyte solution into the epidural space were performed. In one horse of the myeloscopy group, subarachnoid haemorrhage and air occurred, resulting in transient post operative ataxia and muscle fasciculations. No complications during or after myeloscopy were observed in the other horses. CSF analysis indicated mild inflammation on Day 7 with values approaching normal 21 days after surgery.

CONCLUSIONS

Endoscopic examination of the epidural and subarachnoid space from the atlanto-occipital space to the 8th cervical nerve is possible and can be safely performed in healthy horses.

POTENTIAL RELEVANCE

Cervical vertebral canal endoscopy might allow accurate identification of the compression site in horses with CVSM and aid diagnosis of other lesions within the cervical vertebral canal.

First Report of Bulb Disease of Onion Caused by Pantoea ananatis in New York

In winter 2007, disease symptoms were observed in stored yellow onion bulbs (Allium cepa) grown in New York (NY) in 2006. Similar symptoms were observed in bulbs produced in 2007, 2008, and 2009. Symptoms were associated with one to three bulb scales near the midsection. Infected scales were light brown to brown, not macerated, and lacking foul odors typical of onion bulbs infected with Burkholderia cepacia. Onion grower-packers located in Orange County, NY were concerned that onion lots were rejected following grading by inspectors who cut bulbs to check market quality. Extent of the problem statewide is not currently clear. Isolation attempts were made from symptomatic tissues onto nutrient agar plates (3), with incubation for 24 h at 26 to 28°C, and PA-20 (2), a semiselective medium for the isolation of Pantoea ananatis, with similar incubation for 4 to 6 days. Most strains that grew on PA-20 were gram negative and yellow pigmented with dark centers. Isolated strains were tentatively identified as P. ananatis on the basis of growth on PA-20, a positive indole and negative oxidase test, positive tests for catalase, fermentation of glucose, Voges-Proskauer, and citrate utilization; negative for phenylalanine deaminase, urease, nitrate reductase, methyl red tests, and hypersensitive response induction in tobacco. The BIOLOG (Hayward, CA) system indicated that all presumptive strains of P. ananatis utilized d-mannose, d-cellobiose, d-melibiose, l-inositol, d-arabinose, cellulose, glycerol, d-arabitol, and sucrose, but not glycogen, N-acetyl-d-galactosamine, malonic acid, l-fucose, or xylitol. Strains of P. ananatis recovered from diseased onions in Georgia (GA) (1) were included in all tests as positive controls. We used PCR primers suggested by R. D. Gitaitis (University of Georgia): PanITS1 (5'-GTC TGA TAG AAA GAT AAA GAC-3') and AS2b (5'-TTC ATA TCA CCT TAC CGG CGC-3'). Together, they amplify the 16S-23S rDNA internal transcribed spacer region of 398 bp; the nucleotide sequences of six NY and three GA strains are identical to each other and 99.3% identical to P. ananatis LMG 20103 (GenBank CP001875) and 93.3% identical to P. stewartii (AJ311838). Pathogenicity tests were done in onion leaves. For inoculation, strains were grown on nutrient agar for 24 h and bacterial suspensions of ~10⁸ CFU/ml were prepared in sterile water. Tips of healthy, greenhouse-grown onion leaves were cut and inoculum was applied to the cut surfaces with cotton swabs. Plants were incubated in a greenhouse for up to 2 weeks. Plants mock inoculated with water were symptomless. Bacteria were recovered from all lesions induced by artificial inoculation with the presumptive strains of P. ananatis. Recovered bacteria had characteristics of P. ananatis. Pathogenic strains from NY and GA produced off-white lesions that extended the length of the leaf, which was consistent with previous studies of the pathogenicity of P. ananatis (1). On the basis of microbiological and molecular analyses and pathogenicity tests, 14 NY strains, each isolated from a different diseased bulb, were identified as P. ananatis. To our knowledge, this is the first published report of P. ananatis causing a disease of onion in New York. References: (1) R. D. Gitaitis et al. USA Crop Prot. 21:983, 2002. (2) T. Goszczynska et al. J. Microbiol. Methods. 64:22, 2006. (3) N. W. Shaad et al, eds. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2000.

Airway inflammation in Michigan pleasure horses: prevalence and risk factors

REASONS FOR PERFORMING STUDY

Although subclinical airway inflammation is thought to be common in horses, there is little information on its prevalence and none on risk factors.

OBJECTIVE

To determine the prevalence and risk factors for an increased number of inflammatory cells and for mucus accumulation in the trachea of pleasure horses.

METHODS

Horses (n = 266) in stables (n = 21) in Michigan were examined endoscopically, once in winter and once in summer 2004. Visible tracheal mucoid secretions were graded 0-5 and inflammatory cell numbers counted in a tracheal lavage sample. Information collected about each horse included age, gender, presence of cough, percent time indoors and source of roughage. The repeated measures were analysed by generalised estimating equations and linear mixed models.

RESULTS

Horses eating hay, especially from round bales, had the most neutrophils, whereas horses feeding from pasture had the fewest. Being female and being outdoors in winter were associated with increased numbers of inflammatory cells. Older horses had fewer macrophages than young horses. More than 70% of horses had >20% neutrophils in tracheal lavage. Twenty percent of horses had a mucus accumulation score >1; 17% had both a mucus score >1 and >20% neutrophils. The significant risk factors for mucus accumulation >1 were age >15 years, feeding on hay as compared to pasture, and being outdoors for more than 80% time in winter. Even though mucus accumulation score >1 was a risk factor for cough, only half of such horses coughed. Cough and mucus accumulation were associated with increased number of neutrophils.

CONCLUSIONS

In comparison to pasture feeding, hay feeding, particularly from round bales, was associated with an increased number of neutrophils in the airway. Being outdoors in winter was associated with increased numbers of inflammatory cells and with mucus accumulation. Because 70% of horses have >20% neutrophils, this value should not be used as the sole indicator of airway inflammation.

POTENTIAL RELEVANCE

The study reinforces the importance of hay feeding and older age as risk factors for inflammatory airway disease. Horses that do not have 'heaves' may be best kept indoors when winters are cold.

Effect of tracheal mucus and tracheal cytology on racing performance in Thoroughbred racehorses

REASON FOR PERFORMING STUDY

Accumulations of mucus within the trachea are often found during endoscopic examinations of the airways of poorly performing racehorses, but the clinical importance of this finding is unknown.

OBJECTIVES

To determine the effect of tracheal mucus, pharyngeal lymphoid hyperplasia (PLH) and cytological indices of tracheal aspirate on racing performance in Thoroughbred horses assessed by race place and whether the horse was raced.

METHODS

Endoscopic examination of the nasopharynx, larynx and trachea was performed, and a tracheal aspirate obtained monthly at Thistledown racetrack from April to December, 2002 and 2003. Horses received a score of 0-4 for the degree of PLH and 0-4 for the amount of mucus visible in the trachea. The tracheal aspirate was assessed for turbidity, and total and differential cell counts. Generalised estimating equations models were used as repeated measures models for each risk factor and the level of association assessed through the risk factor's P value in the model.

RESULTS

Moderate to severe tracheal mucus (2-4) was a risk factor for poor racing performance. There was no association between degree of PLH, cell counts or turbidity of tracheal wash fluid and racing performance. However, horses that raced had higher total neutrophil counts in tracheal wash aspirates than horses that did not race.

CONCLUSIONS

Grades 2-4 tracheal mucus should be considered a potential cause of poor racing performance in Thoroughbred horses.

CLINICAL RELEVANCE

Because moderate to severe tracheal mucus accumulation, and not increased tracheal neutrophils, was a risk factor for poor racing performance, functionally significant airway inflammation may best be confirmed by the presence of mucus rather than increased number of neutrophils in the trachea.

Expression of a transforming gene (E5) of bovine papillomavirus in sarcoids obtained from horses

OBJECTIVE

To determine expression of a transforming gene (E5) of bovine papillomavirus in sarcoids, other tumors, and normal skin samples collected from horses with and without sarcoids.

SAMPLE POPULATION

23 sarcoids and 6 samples of normal skin obtained from 16 horses with sarcoids, 2 samples of normal skin and 2 papillomas obtained from horses without sarcoids, and 1 papilloma obtained from a cow.

PROCEDURE

Protein was extracted from tissue samples collected from horses and incubated with agarose beads covalently coupled to Staphylococcus aureus protein A and an anti-E5 polyclonal antibody. Following incubation, proteins were eluted from the beads and electrophoresed on a 14% polyacrylamide gel and transferred to a polyvinylidene difluoride membrane. The E5 protein was detected by use of western blot analysis, using a chemiluminescence detection system.

RESULTS

All 23 sarcoids had positive results for expression of E5 protein. Quantity of viral protein appeared to vary among sarcoids. All other tissues examined had negative results for E5 protein. Highest expression for E5 protein was observed in biologically aggressive fibroblastic variants of sarcoids, compared with expression in quiescent tumors.

CONCLUSIONS AND CLINICAL RELEVANCE

This study documented that activation and expression of the E5 gene is evident in sarcoids obtained from horses. These data support the conclusion that infection with bovine papillomavirus is important in the initiation or progression of sarcoids in horses. Treatment strategies designed to increase immune recognition of virally infected cells are warranted.

Bovine papillomavirus DNA in neoplastic and nonneoplastic tissues obtained from horses with and without sarcoids in the western United States

OBJECTIVE

To determine the incidence of bovine papillomavirus (BPV) type 1 or 2 in sarcoids and other samples of cutaneous tissues collected from horses in the western United States.

ANIMALS

55 horses with sarcoids and 12 horses without sarcoids.

PROCEDURE

Tissue samples (tumor and normal skin from horses with sarcoids and normal skin, papillomas, and nonsarcoid cutaneous neoplasms from horses without sarcoids) were collected. Tissue samples were analyzed for BPV-1 or -2 DNA, using a polymerase chain reaction (PCR) and restriction fragment length polymorphism. The PCR products from 7 sarcoid-affected horses were sequenced to evaluate percentage homology with expected sequences for BPV-1 or-2.

RESULTS

Most (94/96, 98%) sarcoids contained BPV DNA. Sixty-two percent of the tumors examined had restriction enzyme patterns consistent with BPV-2. Thirty-one of 49 (63%) samples of normal skin obtained from horses with sarcoids contained BPV DNA. All samples subsequently sequenced had 100% homology with the expected sequences for the specific viral type. All tissues from healthy horses, nonsarcoid neoplasms, and papillomas were negative for BPV DNA.

CONCLUSIONS AND CLINICAL RELEVANCE

Bovine papillomaviral DNA was detected in essentially all sarcoids examined. There appears to be regional variation in the prevalence of viral types in these tumors. The fact that we detected viral DNA in normal skin samples from horses with sarcoids suggests the possibility of a latent viral phase. Viral latency may be 1 explanation for the high rate of recurrence following surgical excision of sarcoids.

Influence of tumor cell proliferation and sex-hormone receptors on effectiveness of radiation therapy for dogs with incompletely resected meningiomas

OBJECTIVE

To assess the influence of tumor cell proliferation and sex-hormone receptors on the efficacy of megavoltage irradiation for dogs with incompletely resected meningiomas.

DESIGN

Longitudinal clinical trial.

ANIMALS

20 dogs with incompletely resected intracranial meningiomas.

PROCEDURE

Dogs were treated with 48 Gy of radiation administered 3 times per week on an alternate-day schedule of 4 Gy/fraction for 4 weeks, using bilateral parallel-opposed fields.

RESULTS

Tumor proliferative fraction measured by immunohistochemical detection of proliferating cell nuclear antigen (PFPCNA index) ranged from 10 to 42% (median, 24%). Progesterone receptor immunoreactivity was detected in 70% of tumors. Estrogen receptor immunoreactivity was not detected. An inverse correlation was found between detection of progesterone receptors and the PFPCNA index. The overall 2-year progression-free survival (PFS) rate was 68%. The only prognostic factor that significantly affected PFS rate was the PFPCNA index. The 2-year PFS was 42% for tumors with a high PFPCNA index (value > or = 24%) and 91% for tumors with a low PFPCNA index (value < 24%). Tumors with a high PFPCNA index were 9.1 times as likely to recur as were tumors with a low PFPCNA index.

CONCLUSIONS AND CLINICAL RELEVANCE

This study confirms the value of irradiation for dogs with incompletely resected meningiomas. Prognostic value of the PFPCNA index suggests-that duration of treatment and interval from surgery to start of irradiation may affect outcome. Loss of progesterone receptors in some tumors may be responsible for an increase in PFPCNA index and may indirectly affect prognosis after radiation therapy.

Changes in left ventricular dynamics during graded exercise

Three mature Thoroughbred horses were prepared surgically with ultrasonic sonomicrometer crystals affixed to their ventricular pericardia. Signals from crystals recorded dimensions of axes across the left ventricle. Cubic algorithms were fitted to dimensional data to generate volume estimates that matched stroke volumes simultaneously measured using the Fick principle. As horses stood at rest or exercised at various intensities (approx 7, 12, 24, 47 and 100% maximal rate of O2 consumption VO2max[), left ventricular dimensions were recorded and 20 consecutive diastolic and systolic volumes calculated. Although Fick estimates detected no difference in stroke volume at different exercise intensities, sonomicrometer measurements of stroke volume were significantly lower at rest and higher at VO2max. These differences mirrored changes in end-diastolic volume, although end-systolic volume did not change. At all exercise intensities, stroke volume was most variable and end-diastolic volume the least. The pattern conforms to the Frank-Starling mechanism, and indicates that at high exercise intensities ventricular myocytes generate high pressures with higher myocardial wall stress due to the increased size of the chamber.

Nasal septoplasty for correction of septal deviation in a foal

OBJECTIVE

This article reports an alternative to septal resection in nasal septal deviations involving the rostral 7 to 10 cm of the nasal septum.

STUDY DESIGN

Case report.

SAMPLE POPULATION

One client-owned foal.

METHODS

A nasal approach with mucosal elevation was used to gain access to the cartilaginous portion of the nasal septum. Once exposed, a series of parasagittal incisions in the cartilage allowed the septum to be repositioned while providing some intrinsic stabilization.

RESULTS

The nasal approach provided good access to the rostral 7 cm of the nasal septum. The technique resulted in minimal hemorrhage from the site. Bleeding was reduced with the use of ephedrine to vasoconstrict the mucosal vessels, and primary closure of the mucosa.

CONCLUSIONS

Use of an intrinsically stabilized septoplasty should be considered as a means of decreasing the airway obstruction caused by nasal septal deviation in foals while allowing for normal development of facial contour.

Acute hemorrhagic pulmonary infarction and necrotizing pneumonia in horses: 21 cases (1967-1993)

OBJECTIVE

To characterize history, clinical signs, and pathologic findings in horses with histologically confirmed acute hemorrhagic pulmonary infarction and necrotizing pneumonia.

DESIGN

Retrospective study.

ANIMALS

21 horses.

RESULTS

19 of the 21 horses were Thoroughbred racehorses in training. Eighteen horses had had strenuous exercise immediately prior to onset of illness. Fifteen horses had a serosanguineous nasal discharge during hospitalization. Seventeen horses had radiographic evidence of pulmonary consolidation and pleural effusion. Nine of 14 horses had ultrasonographic evidence of large pulmonary parenchymal defects consistent with consolidation. Pleurocentesis yielded a suppurative, serosanguineous effusion in the 14 horses in which it was performed. Bacteria were isolated from all transtracheal aspirates (14) and from 6 of 12 pleural fluid samples. Actinobacillus suis-like organisms and Streptococcus equi subsp zooepidemicus were most commonly isolated. Nineteen horses were hospitalized and treated. Mean duration of treatment was 5 days, and most horses were euthanatized because of secondary complications, continued costs of medical treatment, or poor prognosis for future performance. Pathologic lesions included well-demarcated regions of hemorrhagic pulmonary infarction with necrosis and a serosanguineous pleural effusion. Thrombosis of pulmonary vessels was found in 11 horses.

CLINICAL IMPLICATIONS

An acute or peracute onset of severe respiratory distress, with serosanguineous nasal discharge, ultrasonographic and radiographic evidence of severe pulmonary consolidation, and serosanguineous suppurative pleural effusion, is strongly suggestive of pulmonary infarction in horses. Horses with pulmonary infarction responded poorly to conventional treatment for pleuropneumonia and had a poor prognosis for recovery.

Laryngeal and pharyngeal dysfunction in horses homozygous for hyperkalemic periodic paralysis

OBJECTIVE

Evaluate histories, clinical signs, and laboratory data of 69 horses homozygous by DNA testing for hyperkalemic periodic paralysis (HPP).

DESIGN

Cohort study.

SAMPLE POPULATION

69 of 189 horses testing homozygous for HPP between October 1992 and November 1994.

PROCEDURE

Questionnaires addressing signalment, training regimes, medical history, and current status of affected horses were sent to owners, trainers, or attending veterinarians. Data from completed questionnaires were tabulated and evaluated, using descriptive statistics.

RESULTS

Sixty-nine (37%) of 189 questionnaires were completed and returned. Clinical episodes of muscle weakness or paralysis varied in severity and frequency from mild muscle fasciculations to recumbency and death. Sixty-three of 68 HPP-affected horses were reported to have had stridor associated with exercise, excitement, stress, or episodes of muscle paralysis. Common endoscopic findings in affected horses included pharyngeal collapse, pharyngeal edema, laryngopalatal dislocation, and laryngeal paralysis. Twelve of 27 horses receiving acetazolamide had decreases in stridor while receiving medication.

CLINICAL IMPLICATIONS

Most horses testing homozygous for HPP had clinical signs associated with pharyngeal and laryngeal dysfunction. Hyperkalemic periodic paralysis should be included on a differential list for horses examined for signs of laryngeal or pharyngeal dysfunction or stridor. Treatment with acetazolamide may help to control respiratory tract signs associated with this disease.

Uptake and translocation of microparticles in small intestine. Morphology and quantification of particle distribution

The intestinal transit of large (micro-) particles to other sites of the body remains a controversial issue of relevance in various fields of study. In this report fluorescent polystyrene latex microparticles in the size range of 2 microns were used as models for nonspecifically absorbed nonbiodegradable particulates. They were administered to young adult rats as a single oral dose of 1.65 x 10(9) particles; Peyer's patches and surrounding normal absorptive small intestinal tissue were collected at various time points. Quantification of solubilized tissue samples and fluorescence (epi- and confocal) qualitative and quantitative microscopy showed uptake of latex microparticles in all parts of the intestine sampled, but with the proximal segment the preferential site of absorption. The maximum uptake of particles occurred 0.5 hr after dosing in all three segments of the small intestine; there were progressively smaller numbers with distance from the pylorus and with time. Translocation of small numbers of particles to the mesenteric lymph nodes was also detected at 0.5 hr. Transmucosal passage of particles occurred primarily in the villous tissues adjacent to the Peyer's patch regions. These studies give confirmatory evidence for the uptake and translocation of microparticulates across the mucosal barrier and provide new information regarding site- and time-related effects on particle uptake and the involvement of the villous epithelium in particle translocation.

A commentary on morphological and quantitative aspects of microparticle translocation across the gastrointestinal mucosa

It is now generally accepted that particulates in the nano-range (< 1 micron) can and do cross the intestinal mucosa. However, the issue is less well resolved for particles in the micro-range (> 1 micron) and this is discussed in relation to the variety of experimental designs present in the literature. Emphasis is placed on the relative contributions of quantitative bulk tissue analysis with respect to qualitative and quantitative morphological analysis. The discussion is extended to observations on factors influencing the particle translocation process including variation in particle uptake in relation to intestinal region and time post-dose administration based on data for uptake of -2 microns latex particles by rat Peyer's patch tissue. Although a significant body of data now identifies the intestinal processus of particle translocation it is underlined that discrepancies may arise as a consequence of different analytical approaches and that this is an issue to be addressed for valid comparisons of data.

Ruptured urinary bladder after dystocia in a cow

Rupture of the urinary bladder of a cow occurred secondary to prolonged dystocia. Primary surgical closure of the tear was performed after drainage of the uroperitoneum, and the cow recovered without complications.

Uptake of myocardial imaging agents by rejecting and nonrejecting cardiac transplants. A comparative clinical study of thallium-201, technetium-99m, and gallium-67

To study the scintigraphic detectability of cardiac rejection, we performed 135 planar myocardial scans ([99mTc]pyrophosphate, 85; 201Tl, 36; 67Ga, 14) together with endomyocardial biopsies in ten patients for a (mean) 17-mo postoperative period. Specificity of each agent exceeded 89%. Technetium-99m pyrophosphate showed results that significantly correlated with the severity of rejection (p = 0.03), as shown by biopsy, but neither 201Tl nor 67Ga did so (p = 0.63 and 0.81, respectively). Technetium-99m pyrophosphate showed better diagnostic accuracy (85%) than 201Tl (69%) and 67Ga (64%). Technetium-99m pyrophosphate also showed higher negative predictive value (91%) than thallium (76%) and gallium (69%). Thus, a normal 99mTc pyrophosphate scan was usually associated with absence of cardiac rejection. However, all three agents showed unacceptably poor sensitivity (0% to 30%) and thus were not useful as a screening test for cardiac rejection, even when the same agent was used serially in imaging a given patient.

Sulfinpyrazone prolongs survival and decreases platelet uptake of heart allografts

The purpose of this study was to evaluate the potential benefit of the platelet active drug sulfinpyrazone (SPZ) on uptake of indium-III-oxine (111In)-labeled platelets and survival of rat heart allografts. Lewis rats bearing ACI heterotopic heart transplants were treated with SPZ in high, intermediate, or low doses. In 111-labeled platelet uptake was measured 5 days postoperatively and calculated as a ratio between the transplanted and native hearts. Left and right ventricles were measured separately. SPZ given in doses of 400 and 200 mg/kg daily significantly decreased platelet uptake in the graft and reduced the ratio of uptake between transplanted and native hearts (P less than 0.05). In animals treated with SPZ 100 mg/kg/day platelet uptake was not significantly less than that of the nontreated control animals. Survival of allografts was determined by daily palpation and compared to vehicle-treated controls. Mean graft survival was prolonged for animals treated with 100 mg/kg and 200 mg/kg daily, i.e., 19.0 +/- 3.02 and 11.42 +/- 1.97 days, respectively. Animals administered 400 mg/kg did not have longer graft survival than controls (6.63 +/- 0.66 versus 6.31 +/- 0.18 days). Most animals in the 400 mg/kg group died as a result of adverse side effects of the drug. We conclude that SPZ in low to intermediate doses prolongs allografted heart survival. The enhanced survival in the lower dose group may in part be due to mechanisms other than platelet adhesiveness.

Coronary blood flow and thallium 201 uptake in rejecting rat heart transplantations

The effects of rejection on coronary flow (CAF) in heart allografts are unclear, although previous evidence with cardiac imaging agents indicates impaired flow during advanced rejection. The purpose of this study was to measure CAF in heterotopically placed heart grafts. Lewis rats (LEW) received grafts from either syngeneic Lewis rats (LEW/LEW group) or allogeneic ACI rats (ACI/LEW group). CAF was measured in both the transplanted and native hearts with radiolabeled microspheres. Rejection was measured histologically (grades 0 [absent] to 4+ [severe]). In addition systemic blood pressure and cardiac outputs of the native hearts were determined with microspheres. Different animals were studied during relatively early (4 days) and late (6 days) rejection. Among the 4-day animals a cyclosporine-treated group was included (ACI/LEW CyA). In 6-day rats CAF in allografts was lower (0.56 +/- .06 ml/gm/min) compared with syngeneic grafts (1.72 +/- 0.4 ml/gm/min) (p less than 0.05). The CAF in the native hearts did not differ significantly but was higher than in the grafts in both groups. Heart rates were reduced in allografts (p less than 0.05). It is interesting that arterial pressure and cardiac output were significantly lower in animals bearing allogeneic than syngeneic grafts. In rats studied at 4 days graft CAF was lower than in the native heart in both the LEW/LEW and ACI/LEW groups, but there was no significant difference in behavior between groups. The same was true for a cyclosporine-treated group. Graft heart rates were similar in all 4-day rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Uptake of perfusion imaging agents by transplanted hearts: an experimental study in rats

There is a need for a reliable noninvasive marker of rejection in transplanted hearts. Endomyocardial biopsy is now the universally accepted diagnostic method of choice, but the invasiveness of the procedure and the limited size of the sample obtained makes this method far from ideal. As coronary blood flow may be expected to decrease during acute rejection, there has been interest in thallium-201 chloride (T1), a perfusion marker, as an imaging agent for diagnosing cardiac rejection. Hexakis(t-butylisonitrile)-technetium (Tc-TBI) is a representative of a new class of radiopharmaceuticals proposed as perfusion markers. We have compared the uptake of these imaging agents in a rat model of cardiac transplantation. Uptake of Tc-TBI as well as of T1 was significantly lower in rejecting than in nonrejecting hearts. This change was found in both left (LV) and right (RV) ventricles. Allografts in animals treated with cyclosporine (CyA) showed less severe rejection and higher uptakes of both imaging agents as compared to unmodified rejection. Our results suggest that perfusion imaging with these radionuclides is a potentially useful approach to the problem of detecting allograft rejection.

Probenecid inhibition of the renal excretion of dyphylline in chicken, rat and man

The effect of probenecid on the renal excretion of dyphylline was studied in chicken, rat and man. Dyphylline was found to be actively excreted when measured by the Sperber preparation in hens, the isolated perfused kidney of the rat and clearance studies in man. In each study probenecid significantly decreased dyphylline excretion demonstrating that dyphylline occupied the renal organic anion transport system. This same drug interaction, at the level of the renal excretory system, in these three species occurred at comparable concentrations of dyphylline and probenecid.

Uptake of myocardial imaging agents by rejected hearts

Technetium 99 m pyrophosphate, Gallium 67 and Thallium 201 uptakes were measured in heterotopically transplanted rat hearts. Five days after transplantation, Technetium 99 m pyrophosphate, and Gallium 67 uptakes were significantly higher in allogeneic grafts than in syngeneic grafts. At an early stage of rejection (three days after transplantation), only Technetium 99 m pyrophosphate uptake in the left ventricle of allogeneic grafts showed a significant difference (p less than 0.04). At five days, Thallium 201 uptake was significantly lower in allo- than syngeneic grafts. There was a positive correlation between radionuclide uptake and histologic degree of rejection for Technetium 99 m pyrophosphate and Gallium 67 while Thallium 201 uptake correlated negatively. Analysis of variance revealed that hearts with no or minimal rejection had statistically different uptakes than hearts with mild to moderate rejection. These results suggest that uptake of imaging agents might be useful in the diagnosis of rejection of the transplanted heart.

Uptake of technetium-99m methylene diphosphonate by fractured and osteoporotic bone after a pulse dose of vitamin D3

The effect of a pulse dose of Vitamin D3 on uptake of [99mTc]MDP by fractured and osteoporotic bone, respectively, was compared with D3's effect on uptake by normal bone in rats. At 4, 7, and 14 days, respectively, after femoral fracture, basal uptake was significantly (p less than 0.005) increased at the fracture site by 336.8, 276.1, and 183.5%, respectively, over the contralateral control site. D3-treated rats had lower uptakes than untreated controls at all three fracture sites and at 12 of 15 normal bone sites but analysis of variance showed the uptake differences were not significant. Cortisone-induced osteoporosis caused a significant (p less than 0.05) decrease in basal uptake. The decrease occurred in all nine bone areas studied. D3 caused a significant (p less than 0.05) increase (mean 16.2%) in uptake by these osteoporotic bones, but a significant (0.1 greater than p greater than 0.05) decrease (mean 13.0%) in uptake by the same bones in normal controls. Thus, D3 had an effect on uptake by the bone lesion, osteoporosis, that differed from D3's effect on uptake by fracture or normal bone.

Effect of vitamin D3 on imaging of experimental myocardial infarcts with technetium-99m pyrophosphate: further studies of the role of calcium

We previously found that a pulse dose of vitamin D3 increased [99mTc]PPi uptake by rat myocardial necrosis. Vitamin D3 raised serum and lesion [Ca] but not, we now report, lesion [Fe]. We now also report that D3 increased [99Tc]PPi uptake by myocardial infarcts (L) in dogs from 0.345 +/- 0.007% administered (kg) dose/g in controls to 0.703 +/- 0.089 in treated (p less than 0.025). Vitamin D3 decreased uptake by dog bone (B) as measured in rib and sternum, increasing L/B from 1.10 +/- 0.23 to 2.30 +/- 0.52 (p = 0.06) X (L) was positively, (p less than 0.005) and uptake by sternum was negatively (p less than 0.05) correlated with serum [Ca] and [P], respectively. Scintigrams graded by a "blinded" observer, showed 4+, 4+, and 3+ infarcts, respectively, in three D3-treated dogs, and 2+, 2+, and 1+, respectively, in three untreated. One untreated and one treated dog were negative; the latter showed the least response to D3 in serum [Ca] and [99mTc] in tissue samples. Vitamin D3 can increase L/B in dogs, enhancing scintigraphic images.

Effect of vitamin D3, other drugs altering serum calcium or phosphorus concentrations, and desoxycorticosterone on the distribution of Tc-99m pyrophosphate between target and nontarget tissues

Radioactive imaging agents are chemically designed for selective distribution. Another approach to selectivity is to find stable compounds that favorably influence this distribution. Using a rat model of myocardial necrosis, we studied effects of various stable compounds (as a single, large dose or fractionated into short series) on the ratio, uptake of Tc-99m pyrophosphate (PPi) by the target lesion/uptake by the principal nontarget, bone (L/B). Vitamin D3s ability to increase L/B was mediated by the hypercalcemia and hyperphosphatemia that it caused. The hypercalcemia was accompanied by increased [Ca] in the lesion. In contrast, pulse doses of desoxycorticosterone acetate (DOCA) at 7 and 6 hr before killing increased uptake by lesion, increasing L/B from 0.19 +/- 0.03 to 0.45 +/- 0.08 (p less than 0.01), with no change in serum [Ca] and minimal changes in serum [P], [Na], and [K]. DOCA also increased the lesion-to-blood ratio from 6.5 +/- 0.07 to 15.4 +/- 3.9 (p less than 0.05). These results encourage further study of DOCA's effect and investigation of other stable drugs that may influence distribution of other imaging agents.

Studies of uptake of the bretylium analogue, iodobenzyltrimethylammonium iodide, by non-primate, monkey and human hearts

Uptake of (+/-)-[3H]-noradrenaline, [14C]-bretylium and [125I]-o-iodobenzyltrimethylammonium iodide (RIBA) by rat heart was studied by the Langendorff technique. All three compounds showed significant uptake. 2 Corticosterone and 17-beta-oestradiol inhibited the uptake of all three compounds by rat heart, a finding consistent with extraneuronal uptake (uptake2). 3 [131I]-RIBA was injected intravenously into pigs and monkeys (M. speciosus). Myocardial samples taken from pigs killed 1 and 2 h after injection showed significant uptake. No significant uptake was found in myocardial samples of monkeys killed 10 min, 2 h and 24 h, respectively, after injection. 4 Four normal human volunteers received [125I]-RIBA intravenously and the image of the precordial area was followed by means of scintillation camera for the first 4 h after injection. In two of the subjects, the scintigrams were repeated at 22 and 23 h after injection, respectively. No evidence of myocardial uptake was observed. 5 These results suggest the possibility that man and at least one other primate species may differ from lower species with regard to uptake.

A radioiodinated bretylium analog as a potential agent for scanning the adrenal medulla

Studies with radioiodinated bretylium analogs (RIBA) suggested that the p-isomer was capable of concentrating in adrenal medulla. The present studies with 125I-p-RIBA in rats and dogs confirm this property and show its marked and persistent affinity for the adrenal medulla. Analogous studies with 14C-p-IBA indicate that it is the quaternary form of the drug that is retained by the adrenal and that high thyroidal radioactivity following 125I-p-RIBA administration is due to in vivo deiodination of the drug.

Panel 2: phase II investigations

At the end of Phase II, a decision must be made as to whether or not the drug should be developed as a therapeutic agent. Such a decision may be based on many criteria in addition to the scientific data derived from the Phase II study. At this point, expert judgment is needed. One should like to assume that if the decision is made to proceed with the increasingly expensive and laborious process of further development, the drug will, barring some completely unforeseen misadventure, ultimately find its way into clinical therapeutics. Phase II studies, therefore, are the most crucial stage in the course of drug development. Planning of these studies requires great care and investigators of the highest caliber should be used for their conduct. The escalating costs of new drug development are resulting in an undesirable imbalance of efforts in the direction of studies characterized more by easily defined end points than by therapeutic needs. Industry, academia, and the FDA must all be concerned with facilitationg studies in areas of most-needed therapeutic advances.

Energy reserves in transplanted and sham-operated carciac tissue=

Tissue levels of creatine phosphate (CP), creatine, adenosine-triphosphate(ATP), inorganic phosphate (Pi), glycogen, glucose and lactate were determined in heterotopically transplanted and recipient hearts as well as in the myocardium of sham-operated rabbitsmthe ATPase activity in these tissues was also estimatedmthe results revealed no biochemical indication of ischemic conditions in the transplanted organs relative to the other investigated tissue. The tissue levels of CP in the donor heart were even higher then in both the recipient and sham-operated organs. The concentrations of the other above listed compounds in all the studied tissue were similar throughout the first 5 post-operative days. The effect of surgery was manifested in decreased levels of CP, still prevailing 3 days post-operative in all of the investigated tissue. However, on the fifth day after surgery, the tissue concentration of CP showed a trend toward recovery. The activity of Na,K-ATPase in both donor and recipient hearts was similar. One day after surgery, the activity of the Mg-ATPase was 27% lower relative to its value on days 3 and 5 post-operatively. However no correlation was obtained between the change in Mg-ATPase and tissue concentrations of ATP.