A phase IIa, randomized, double-blind, safety, immunogenicity and efficacy trial of Plasmodium falciparum vaccine antigens merozoite surface protein 1 and RTS,S formulated with AS02 adjuvant in healthy, malaria-naïve adults

BACKGROUND

To improve the efficacy of Plasmodium falciparum malaria vaccine RTS,S/AS02, we conducted a study in 2001 in healthy, malaria-naïve adults administered RTS,S/AS02 in combination with FMP1, a recombinant merozoite surface-protein-1, C-terminal 42kD fragment.

METHODS

A double-blind Phase I/IIa study randomized N = 60 subjects 1:1:1:1 to one of four groups, N = 15/group, to evaluate safety, immunogenicity, and efficacy of intra-deltoid half-doses of RTS,S/AS02 and FMP1/AS02 administered in the contralateral (RTS,S + FMP1-separate) or same (RTS,S + FMP1-same) sites, or FMP1/AS02 alone (FMP1-alone), or RTS,S/AS02 alone (RTS,S-alone) on a 0-, 1-, 3-month schedule. Subjects receiving three doses of vaccine and non-immunized controls (N = 11) were infected with homologous P. falciparum 3D7 sporozoites by Controlled Human Malaria Infection (CHMI).

RESULTS

Subjects in all vaccination groups experienced mostly mild or moderate local and general adverse events that resolved within eight days. Anti-circumsporozoite antibody levels were lower when FMP1 and RTS,S were co-administered at the same site (35.0 µg/mL: 95 % CI 20.3-63), versus separate arms (57.4 µg/mL: 95 % CI 32.3-102) or RTS,S alone (62.0 µg/mL: 95 % CI: 37.8-101.8). RTS,S-specific lymphoproliferative responses and ex vivo ELISpot CSP-specific interferon-gamma (IFN-γ) responses were indistinguishable among groups receiving RTS,S/AS02. There was no difference in antibody to FMP1 among groups receiving FMP1/AS02. After CHMI, groups immunized with a RTS,S-containing regimen had ∼ 30 % sterile protection against parasitemia, and equivalent delays in time-to-parasitemia. The FMP1/AS02 alone group showed no sterile immunity or delay in parasitemia.

CONCLUSION

Co-administration of RTS,S and FMP1/AS02 reduced anti-RTS,S antibody, but did not affect tolerability, cellular immunity, or efficacy in a stringent CHMI model. Absence of efficacy or delay of patency in the sporozoite challenge model in the FMP1/AS02 group did not rule out efficacy of FMP1/AS02 in an endemic population. However, a Phase IIb trial of FMP1/AS02 in children in malaria-endemic Kenya did not demonstrate efficacy against natural infection.

CLINICALTRIALS

gov identifier: NCT01556945.

Infliximab is associated with attenuated immunogenicity to BNT162b2 and ChAdOx1 nCoV-19 SARS-CoV-2 vaccines in patients with IBD

OBJECTIVE

Delayed second dose SARS-CoV-2 vaccination trades maximal effectiveness for a lower level of immunity across more of the population. We investigated whether patients with inflammatory bowel disease treated with infliximab have attenuated serological responses to a single dose of a SARS-CoV-2 vaccine.

DESIGN

Antibody responses and seroconversion rates in infliximab-treated patients (n=865) were compared with a cohort treated with vedolizumab (n=428), a gut-selective anti-integrin α4β7 monoclonal antibody. Our primary outcome was anti-SARS-CoV-2 spike (S) antibody concentrations, measured using the Elecsys anti-SARS-CoV-2 spike (S) antibody assay 3-10 weeks after vaccination, in patients without evidence of prior infection. Secondary outcomes were seroconversion rates (defined by a cut-off of 15 U/mL), and antibody responses following past infection or a second dose of the BNT162b2 vaccine.

RESULTS

Geometric mean (SD) anti-SARS-CoV-2 antibody concentrations were lower in patients treated with infliximab than vedolizumab, following BNT162b2 (6.0 U/mL (5.9) vs 28.8 U/mL (5.4) p<0.0001) and ChAdOx1 nCoV-19 (4.7 U/mL (4.9)) vs 13.8 U/mL (5.9) p<0.0001) vaccines. In our multivariable models, antibody concentrations were lower in infliximab-treated compared with vedolizumab-treated patients who received the BNT162b2 (fold change (FC) 0.29 (95% CI 0.21 to 0.40), p<0.0001) and ChAdOx1 nCoV-19 (FC 0.39 (95% CI 0.30 to 0.51), p<0.0001) vaccines. In both models, age ≥60 years, immunomodulator use, Crohn's disease and smoking were associated with lower, while non-white ethnicity was associated with higher, anti-SARS-CoV-2 antibody concentrations. Seroconversion rates after a single dose of either vaccine were higher in patients with prior SARS-CoV-2 infection and after two doses of BNT162b2 vaccine.

CONCLUSION

Infliximab is associated with attenuated immunogenicity to a single dose of the BNT162b2 and ChAdOx1 nCoV-19 SARS-CoV-2 vaccines. Vaccination after SARS-CoV-2 infection, or a second dose of vaccine, led to seroconversion in most patients. Delayed second dosing should be avoided in patients treated with infliximab.

TRIAL REGISTRATION NUMBER

ISRCTN45176516.

A Systematic Review on Infliximab Biosimilar SB2: From Pre-Clinical Data to Real-World Evidence

INTRODUCTION

The infliximab biosimilar SB2 was approved in the EU (2016, Flixabi®) and the US (2017, Renflexis®) for the same indications as the reference product (Remicade®) based on a robust analytical and clinical data package.

AREAS COVERED

This systematic literature review summarizes available analytical and clinical data on SB2, including randomized controlled clinical trials and real-world evidence studies. Overall, 184 articles and congress abstracts were identified (excluding duplicates), whereof 5 reports on analytical data, four reports on two randomized controlled trials and 13 reports of real-world evidence studies were included.

EXPERT OPINION

The available analytical and clinical data support the equivalence of SB2 to the reference product across approved indications. This is further supported by emerging real-world evidence, particularly in extrapolated indications such as inflammatory bowel disease for both infliximab-naïve patients and patients already established on infliximab switching to SB2. Switching from originator or biosimilar infliximab to SB2 including both single and multiple switches was not associated with an increased risk of loss of treatment response or any safety or immunogenicity concerns. Overall, the approved infliximab biosimilar SB2 is safe and effective in clinical practice across licensed indications.

Ferric maltol Real-world Effectiveness Study in Hospital practice (FRESH): clinical characteristics and outcomes of patients with inflammatory bowel disease receiving ferric maltol for iron-deficiency anaemia in the UK

Objective

To assess outcomes in patients with iron-deficient inflammatory bowel disease (IBD) treated with ferric maltol in UK real-world practice.

Design/Method

This observational, multicentre, retrospective cohort study included adults with IBD and iron-deficiency anaemia (IDA; haemoglobin ≥95 to <120 g/L (women) or ≥95 to <130 g/L (men) plus serum ferritin <30 µg/L or transferrin saturation <20%) who received ferric maltol. Data were extracted from patient records. The primary analysis was the proportion of patients with normalised haemoglobin (≥120 g/L (women); ≥130 g/L (men)) over 12 weeks. Iron indices and safety were assessed.

Results

Thirty of 59 patients had data for the primary outcome, 19 of whom (63%) achieved haemoglobin normalisation at week 12. Mean±SD haemoglobin was 127±16 g/L at week 12 (increase of 14±17 g/L from baseline). Overall, 27 patients achieved haemoglobin normalisation by the end of the observation period; mean±SD time to normalisation was 49.5±25.6 days. Nine of 17 patients had normalised serum ferritin (30–300 µg/L) at week 12, and 16 patients had normalised ferritin at the end of the observation period; mean±SD time to normalisation was 71.3±27.6 days. Twenty-four adverse events occurred in 19 patients (32%); most frequent adverse events were abdominal pain or discomfort (n=9) and constipation (n=3).

Conclusion

Ferric maltol increases haemoglobin and iron indices and is generally well tolerated in patients with IBD and IDA treated in clinical practice. These real-world data support findings from randomised controlled trials.

Consensus recommendations for patient-centered therapy in mild-to-moderate ulcerative colitis: the i Support Therapy-Access to Rapid Treatment (iSTART) approach

Symptomatic ulcerative colitis (UC) can be a chronic, disabling condition. Flares in disease activity are associated with many of the negative impacts of mild-to-moderate UC. Rapid resolution of flares can provide benefits to patients and healthcare systems. i Support Therapy–Access to Rapid Treatment (iSTART) introduces patient-centered care for mild-to-moderate UC. iSTART provides patients with the ability to self-assess symptomology and self-start a short course of second-line treatment when necessary. An international panel of experts produced consensus statements and recommendations. These were informed by evidence from systematic reviews on the epidemiology, mesalazine (5-ASA) treatment, and patient use criteria for second-line therapy in UC. Optimized 5-ASA is the first-line treatment in all clinical guidelines, but may not be sufficient to induce remission in all patients. Corticosteroids should be prescribed as second-line therapy when needed, with budesonide MMX^® being a preferred steroid option. Active involvement of suitable patients in management of UC flares has the potential to improve therapy, with patients able to show good accuracy for flare self-assessment using validated tools. There is a place in the UC treatment pathway for an approach such as iSTART, which has the potential to provide patient, clinical and economic benefits.

A phase 1 study of a meningococcal native outer membrane vesicle vaccine made from a group B strain with deleted lpxL1 and synX, over-expressed factor H binding protein, two PorAs and stabilized OpcA expression

This phase I clinical trial assessed the safety and immunogenicity of a native outer membrane vesicle (NOMV) vaccine prepared from an lpxL1(-) synX(-) mutant of strain 8570(B:4:P1.19,15:L8-5) of Neisseria meningitidis. Additional mutations enhance the expression of factor H binding protein variant 1 (fHbp v.1), stabilize expression of OpcA and introduce a second PorA (P1.22,14). Thirty-six volunteers were assigned to one of four dose groups (10, 25, 50 and 75 mcg, based on protein content) to receive three intramuscular injections at six week intervals with aluminum hydroxide adjuvant. Specific local and systemic adverse events were solicited by diary and at visits on days 2, 7, and 14 after each vaccination. Blood chemistries, complete blood count, and coagulation studies were measured on each vaccination day and again 2 and 14 days later. Blood for ELISA and serum bactericidal assays was drawn two and six weeks after each vaccination. The proportion of volunteers who developed a fourfold or greater increase in bactericidal activity to the wild type parent of the vaccine strain at two weeks after the third dose was 27 out of 34 (0.79, 95% C.I. 0.65-0.93). Against four other group B strains the response rate ranged from 41% to 82% indicating a good cross reactive antibody response. Depletion assays show contributions to bactericidal activity from antibodies to lipooligosaccharide (LOS), fHbp v.1 and OpcA.

The progression of anterior translation after anterior cruciate ligament reconstruction in a caprine model

Large post-operative anterior-posterior translations are frequently reported after quadruped anterior cruciate ligament (ACL) reconstructions. To determine when the translation increases occur and the mechanism responsible, we followed the anterior and posterior translation limits in 18 goat knees for six months. Reconstructions were performed using grafts 4 or 7 mm wide placed in initially tight or lax positions. The anterior and posterior translation limits at 50 N were monitored using Roentgen stereophotogrammetric analysis. Graft bone block stability and soft tissue segment lengths were also assessed. Large (> 2 mm) increases in anterior translation were noted in 71% of the subjects at two weeks, and in 88% at eight weeks. The translations in the lax and tight groups were indistinguishable after two weeks. Joints with wide grafts had less anterior translation compared to narrow grafts at all time periods, but were significant different only at 26 weeks. The posterior translation limit moved anteriorly over the 26 weeks. Eight of nine joints had stable graft bone markers and/or increases in graft soft tissue lengths. In conclusion, increased anterior translation occurred soon after ACL reconstruction, was associated with graft soft tissue changes, and appeared to be reduced by larger grafts. A post-surgical decrease in posterior translation limit was also observed.

Subject variation in caprine anterior cruciate ligament reconstruction

We studied the subject and treatment contributions to anterior cruciate ligament (ACL) reconstruction biomechanics by reexaming the results of two bilateral reconstruction studies. Bilateral reconstruction allows a comparison between treatments exposed to the same subject related healing factors. The studies examined the effects of gamma irradiation and the effects of initial graft size and initial graft laxity. In both studies different treatments were applied to contralateral limbs. We found that the subject was the best predictor of outcome, while the surgical treatments had little influence on outcome. There was a large variation between subjects despite similar treatments, and little difference between contralateral limbs despite different surgical treatments. At 26 weeks, the graft cross sectional area and modulus were most strongly influenced (p < 0.002) by the subject. We interpret this as a subject related factor is regulating the quantity and quality of the healing tissue. Potential sources of subject related factors include the subject's pre-operative condition, the activity during the post-operative period, and an intrinsic biologic response. By better understanding the source of subject variation, more successful and consistent ACL reconstructions might be achieved.

The effects of graft width and graft laxity on the outcome of caprine anterior cruciate ligament reconstruction

We studied how initial graft size and initial graft laxity affected the biomechanics of anterior cruciate ligament (ACL) reconstruction at six months. Sixteen goats had bilateral reconstructions staged eight weeks apart. Autografts 4 and 7 mm wide were taken from the central patellar tendon (PT). Lax grafts were created by adding 4 mm slack to the graft before fixing. We reconstructed each joint using a combination of width and laxity treatments. Both factors were changed for the contralateral joint and all combinations appeared with equal frequency. At six months we measured the joint extension limit, anterior-posterior (AP) translation, and osteoarthritic changes. The grafts were then tested to failure to determine their mechanical properties. After six months the difference in initial treatments had disappeared: there was no difference in graft cross-section due to the different initial widths and there was no difference in joint AP translation due to the initial graft laxity. We did observe that wide grafts were associated with a block to extension, decreased joint AP translation, and increased articular cartilage damage and osteophyte formation. While AP translation was reduced, it was correlated with decreased extension, possibly indicating an increase in scar tissue formation rather than a more functional graft. Neither graft width nor graft laxity produced differences in any graft mechanical properties. This suggests that the use of larger grafts to prevent increased AP translation has undesirable complications. Ultimately, we conclude that neither of these surgical treatments strongly affects the biomechanical result of caprine ACL reconstruction.

Gastrointestinal stromal tumors in equids

Eleven gastrointestinal neoplasms from 10 aged horses and 1 pony were examined grossly, his tologically, immunohistochemically, and (in two cases) ultrastructurally. Clinical signs were associated with two neoplasms, and the other nine tumors were incidental findings at laparotomy or necropsy. The neoplasms were solitary (9/11) or multifocal (2/11), well demarcated, serosal or mural masses of stomach (1), jejunum (1), ileum (3), cecum (5), and/or colon (2). Microscopic examination revealed discrete spindle cells arranged in compact patterns with fascicles and whorls or cribriform pattern with fascicles and rare palisades, often with a myxoid interstitial matrix. Three tumors infiltrated between the muscularis interna and the muscularis externa at the myenteric plexi. All neoplasms were vimentin positive, 3/11 were S-100 positive, 2/11 were muscle actin positive, and no neoplasm was positive for glial fibrillary acid protein, desmin, factor VIII, chromogranin, or neuron-specific enolase. Of the two tumors studied ultrastructurally, one contained an admixture of smooth muscle cells and cells resembling Schwann cells, and the second was populated by homogeneous fusiform mesenchymal cells separated by homogeneous matrix. Gastrointestinal stromal tumors (GIST) have been recognized in humans, more recently in dogs and nonhuman primates, and now in equids. Most of these tumors are comprised of a loosely arranged network of spindled cells separated by myxoid matrix. GIST may be composed of myogenic, neurogenic, combined myogenic and neurogenic, and undifferentiated mesenchymal cells.

New World monkey efficacy trials for malaria vaccine development: critical path or detour?

Neither GMP malaria antigens nor GMP vaccines have been compared for efficacy in monkeys and humans. It is too risky to base categorical (go/no go) development decisions on results obtained using partially characterized (non-GMP) antigens, adjuvants that are too toxic for human use or unvalidated primate models. Such practices will lead to serious errors (e.g. failure to identify and stop flawed efforts, rejection of effective vaccine strategies) and unjustifiable delays. Successful malaria vaccine development will emphasize definitive field trials in populations at risk of malaria to define and improve vaccine efficacy.

A miniature suture tensiometer for laparoscopic applications

The tension applied to sutures can affect their performance. In laparoscopic procedures, the ability to tension sutures may be compromised by the confined space. The ability to accurately judge tension may also be compromised by lever arms of long instruments and interaction between the instrument and trocar. A miniature suture tensiometer that can be used in open and laparoscopic settings has been developed that demonstrates a maximum error of 0.05 lb over a 2-lb range. This device has been used in laparoscopic surgery to measure suture tension. The suture tension information gathered has been used in the development of a device that reliably delivers a secure knot in a laparoscopic setting.

Concentrations of trace minerals in the spinal cord of horses with equine motor neuron disease

OBJECTIVE

To compare concentrations of trace minerals in the spinal cord of horses with equine motor neuron disease (EMND) with those of horses without neurologic disease (control horses).

ANIMALS

24 horses with EMND and 22 control horses.

PROCEDURE

Spinal cord trace mineral concentrations in horses with EMND and control horses were analyzed by use of inductively coupled plasma atomic emission spectroscopy (calcium, phosphorus, sodium, potassium, magnesium, copper, iron, manganese, nickel, zinc, aluminum, cobalt, and chromium), atomic absorption spectrophotometry (lead and cadmium), flameless atomic absorption (mercury), and fluorometry (selenium).

RESULTS

Copper concentration was significantly higher in the spinal cord of horses with EMND, compared with control horses; spinal cord concentrations of all other trace minerals were similar between groups.

CONCLUSION AND CLINICAL RELEVANCE

Among spinal cord trace minerals investigated in the study, only copper concentrations were significantly different between horses with EMND and horses without neurologic disease, which suggests that copper may be involved in the pathogenesis of EMND. An hypothesis of oxidative injury in this disease is supported by the finding of increased copper concentrations in the spinal cord and by low vitamin E concentrations reported by other researchers.

Staple pull-out strength in an animal model of Cooper's ligament

STUDY OBJECTIVE

To understand the effect of staple number, orientation, and configuration on pull-out strength in an animal model of Cooper's ligament, and compare it with force to knot failure or suture breakage.

DESIGN

Comparative study (Canadian Task Force classification I).

SETTING

Ethicon Endo-Surgery Institute, Cincinnati, Ohio.

SUBJECTS

Fibrous connective tissues from bovine ischia were the tissue model.

INTERVENTION

Specimens were fixed in a cement-plaster compound and mounted in a tensiometer. Endoscopic staples were used to hold a loop of 0-braided polyester suture to the tissue.

MEASUREMENTS AND MAIN RESULTS

The suture loop was pulled perpendicularly away from tissue at a constant rate of 2.1 mm/second and peak force to staple pull-out was recorded. Two staple orientations and four staple configurations were studied. Tests were applied in a factorial arrangement. Ten-millimeter stitches of 0-braided polyester suture in the model were also tested. Maximum force to staple pull-out depended on staple number, orientation, and configuration. Peak force required to remove two staples was significantly higher than that to remove one. Spacing between two staples was less important. Pull-out strength was significantly higher when staples were placed parallel to tissue fibers. Stitches placed perpendicular to fibers failed at the knot or by suture breakage with a mean force approximately two times the peak force to remove two staples.

CONCLUSION

Two staples placed 2 to 5 mm apart parallel to tissue fibers resulted in the greatest pull-out strength of studied configurations.

Quantitative assessment of motor neuron loss in equine motor neuron disease (EMND)

The mean number of motor neurons was assessed in the C7 spinal cord segment of 5 EMND and 5 control horses. Mean number per section in EMND horses was reduced significantly (P<0.001). The mean neuronal loss was estimated at 31%. Each of the 5 affected horses had a mean neuronal count below the 95% confidence interval for control horses. The statistically significant difference between the 2 groups was consistent in the cranial, middle and caudal thirds of the C7 segment (P<0.001). The results of regression analysis indicated an association between neuronal reduction in EMND horses and the duration of the disease when adjusted for age (P<0.001). This is the first quantitation of the neurodegenerative loss in EMND and it provides a clearer explanation for residual deficits in horses that survive EMND.

Adult-onset motor neuron disease in three cats

Motor neuron diseases of domestic animals have rarely been described. Three cats with adult-onset, chronic, progressive generalized muscle weakness characterized initially by trembling on exertion and later by extreme difficulty in walking, cervical ventroflexion, dysphagia, and marked muscle atrophy were elevated. Spinal reflexes were evident early but were nondetectable as the disease progressed. Electromyography revealed fibrillation potentials, with nerve conduction velocities within the reference range. Histologic examination of muscle specimens revealed denervation. Marked neuron loss and gliosis were detected in the ventral horns of the spinal cord, with atrophy of ventral nerve rootlets. Less dramatic neuron loss was seen in brain stem motor nuclei. Electron microscopic examination of the ventral horns disclosed hypertrophied astrocytes, with densely arrayed intermediate filaments, swollen axons with large filamentous accumulations, and many macrophages with lipofuscin-like inclusions. Clinical and pathologic findings were consistent with a progressive neurodegenerative disease affecting spinal and some bulbar motor nuclei.

Intrinsic, management, and nutritional factors associated with equine motor neuron disease

OBJECTIVE

To identify intrinsic, management, nutritional, and environmental risk factors associated with equine motor neuron disease (EMND) and to determine whether epidemiologic evidence supports oxidative stress as a risk factor for developing EMND.

DESIGN

Case-control study.

ANIMALS

87 horses with EMND and 259 control horses.

PROCEDURE

Information concerning each horse's history of exposure to multiple environmental factors prior to developing EMND was obtained by means of a questionnaire or personal interview. Exposure histories of horses with EMND and control horses were compared, and the association of each risk factor with EMND was evaluated, using logistic regression analysis.

RESULTS

Factors significantly associated with risk of developing EMND included age, breed of horse, duration of residence at the farm, not vaccinating against rabies, and certain feeding practices. Horses that were exercised on green pasture or in grass paddocks were less likely to develop EMND, compared with horses that were exercised in dirt pad-docks. Feeding complete pelleted feed as the only source of concentrate or combined with sweet feed was associated with a significant increase in the risk of EMND. Supplementary feeding of vitamin and mineral mixtures not formulated to provide vitamin E or selenium was associated with increased risk of EMND. Horses with a history of cribbing or coprophagia were also at higher risk of developing EMND.

CLINICAL IMPLICATIONS

Several husbandry practices and intrinsic characteristics of horses appear to modify the risk of EMND. The relationship of specific nutritional factors to EMND supports the hypothesis that a deficiency of vitamin E contributes to the disease.

Association between plasma vitamin E concentration and the risk of equine motor neuron disease

Equine motor neuron disease (EMND) is a neurodegenerative disorder of the somatic lower motor neurons that results in a syndrome of diffuse neuromuscular disease in the adult horse. The aetiology of this disorder is unknown, although prior studies have suggested that a deficiency in the lipid antioxidant vitamin E (alpha-tocopherol) contributes to the development of EMND. This paper describes a case-control study designed to investigate the association between plasma vitamin E levels and the risk of EMND for horses. Signalment, plasma vitamin E levels at the time of referral, and information relative to dietary and management practices were collected from 53 horses diagnosed with EMND and 69 controls. The mean plasma vitamin E concentration in EMND cases was significantly lower than that of control horses. After controlling for other risk factors of EMND, there was a statistically significant association between plasma vitamin E levels and EMND, with the likelihood of the disease increasing as the vitamin E concentration decreased. These findings support the reported role of vitamin E deficiency as one of the risk factors for EMND.

A canine encephalomyelopathy with morphological abnormalities in mitochondria

A progressive encephalomyelopathy of insidious onset affecting a 16-month-old dog is described. Clinically, the dog was ataxic, stumbled into objects and showed mild behavioral abnormalities. Light microscopic findings included profound degeneration and astrogliosis of the optic pathways, loss of Purkinje neurons, focal bilateral and symmetrical brain stem spongiosis and diffuse neuroaxial astrogliosis with swollen and abnormally shaped nuclei. Ultrastructurally, there were giant and bizarre mitochondria within neuronal perikarya and axons as well as diffuse loosening of the cerebral and cerebellar neuropil. These neuropathological findings resemble the mitochondrial encephalomyopathies of man.

Hypopituitarism following coronary artery bypass surgery

Coronary artery bypass surgery (CABS) is a common operation, which is often complicated by neurological sequelae. Disturbances of cerebral blood flow have been reported up to eight days after surgery and pituitary apoplexy has previously been reported. We report a case of hypopituitarism without pituitary apoplexy, which developed after a period of sustained arterial hypotension, during coronary artery bypass surgery.

Evaluation of somatostatin analogues for the detection and treatment of gastrinoma in a dog

Gastrinomas in dogs are difficult to diagnose, localise and treat. In humans, somatostatin analogues have improved localisation and treatment of gastrinomas. The somatostatin analogues pentetreotide and octreotide were evaluated for the detection and treatment of gastrinoma in a dog. 111indium-pentetreotide scintigraphy revealed multiple areas of activity in the patient's mid-ventral abdomen which were consistent with masses in the pancreas and liver at laparotomy. Immunohistochemistry, electron microscopy and binding of 125I-[Tyr3]-octreotide in vitro confirmed the lesion as a gastrinoma which expressed somatostatin receptors. Octreotide at doses of 2, 4 and 8 micrograms/kg caused transient decreases in circulating gastrin. Plasma somatostatin peaked at one hour after octreotide and was still detectable at four and six hours after administration of octreotide. Combination therapy with famotidine, omeprazole, sucralfate and increasing doses of octreotide allowed patient survival for 14 months.

Hereditary polioencephalomyelopathy of the Australian cattle dog

A vacuolar degeneration affecting primarily the gray matter in the central nervous system (CNS) of young Australian Cattle Dogs is described. An initial presentation of seizures was followed by a progressive spastic tetraparesis. Grossly evident bilateral and symmetrical foci of malacia were in the nuclei of the cerebellum and brain stem and the gray matter of the spinal cord. Microscopically, vacuolation of glial cells, dilation of the myelin sheaths and reactive astrocytosis characterized mild CNS changes. More advanced lesions displayed progressive dissolution of the neuropil, prominent vacuolation of reactive astrocytes, numerous glial fibrillary acidic protein-positive coiled astrocytic processes, neuronal vacuolation and loss with relative sparing of large neurons. Ultrastructurally marked mitochondrial accumulation and swelling were seen in astrocytes. In the appendicular muscles, changes interpreted as long-term denervation atrophy accompanied by widespread expression of the neonatal isoform of myosin were observed. The character of the neurological sings, the nature and the distribution of the lesions within the neuroaxis have not been reported in domestic animals. An inherited biochemical defect, possibly mitochondrial, is proposed as the cause. Selected conditions with a bilateral and symmetrical distribution affecting the gray matter of domestic animals are summarized.

Severe polysaccharide storage myopathy in Belgian and Percheron draught horses

A severe myopathy leading to death or euthanasia was identified in 4 Belgian and 4 Percheron draught horses age 2-21 years. Clinical signs ranged from overt weakness and muscle atrophy in 2 horses age 2 and 3 years, to recumbency with inability to rise in 6 horses age 4-21 years. In 5 horses there was mild to severe increases in muscle enzyme levels. Clinical diagnoses included equine motor neuron disease (2 horses), post anaesthetic myopathy (2 horses), exertional myopathy (2 horses), myopathy due to unknown (one horse), and equine protozoal myelitis (one horse). Characteristic histopathology of muscle from affected horses was the presence of excessive complex polysaccharide and/or glycogen, revealed by periodic acid-Schiff staining in all cases and by electron microscopy in one case. Evaluation of frozen section histochemistry performed on 2 cases indicated that affected fibres were Type 2 glycolytic fibres. Subsarcolemmal and intracytoplasmic vacuoles were most prominent in 3 horses age 2-4 years, and excessive glycogen, with little or no complex polysaccharide, was the primary compound stored in affected muscle in these young horses. Myopathic changes, including fibre size variation, fibre hypertrophy, internal nuclei, and interstitial fat infiltration, were most prominent in 5 horses age 6-21 years, and the accumulation of complex polysaccharide appeared to increase with age. Mild to moderate segmental myofibre necrosis was present in all cases.

Equine motor neuron disease

This article reviews the subject of equine motor neuron disease, a neurodegenerative disease of horses. The authors discuss various topics, including epidemiology, pathophysiology, clinical signs, laboratory findings, diagnosis, and treatment.

Equine motor neuron disease is not linked to Cu/Zn superoxide dismutase mutations: sequence analysis of the equine Cu/Zn superoxide dismutase cDNA

The cDNA encoding the equine copper/zinc superoxide dismutase (SOD1) was cloned from leukocyte total RNA from healthy horses and its nucleotide (nt) sequence was determined. We further sequenced the SOD1 gene from 16 horses diagnosed with equine motor neuron disease (EMND) and eight unrelated, clinically normal horses to determine if this disease, similar to amyotrophic lateral sclerosis (ALS) in humans, is linked to SOD1 mutations. The 465-bp SOD1 coding region in the horse encodes 153 amino acid (aa) residues. Equine SOD1 exhibited 81.8 and 79.9% sequence identity to the human homolog at the nt and aa levels, respectively, with only five distinct aa in the two loops that constitute the active site of the enzyme. None of the human SOD1 mutations found in the familial form of ALS were detected in SOD1 of the 16 affected horses. Although DNA sequence analysis identified three potential polymorphisms in equine SOD1, these were silent and were found in both normal and EMND-afflicted horses. At this time, there is no conclusive evidence for EMND linkage to SOD1 mutations.

How have patients reacted to the implications of the DCCT?

OBJECTIVES

To assess the reactions of people with insulin-treated diabetes (ITD) to the results of the Diabetes Control and Complications Trial (DCCT).

RESEARCH DESIGN AND METHODS

A leaflet documenting the purpose and results of the DCCT was circulated to all 771 patients ages 15-60 years with ITD attending our clinic. Patients were invited to complete and return a questionnaire on their responses.

RESULTS

Of 550 respondents, 330 felt encouraged to improve glycemic control. Female respondents (P = 0.003) and younger age-groups (15-25 years, P = 0.001) were most likely to want to improve control. Patients with long duration of diabetes (> 20 years, P = 0.00001), hypoglycemia unawareness (P = 0.0001), or previous severe hypoglycemia (P = 0.001) were less likely to want to improve their control. Fear of hypoglycemia concerned all age-groups, whereas female respondents were most likely to be worried about the potential for weight gain (P = 0.00006).

CONCLUSIONS

Knowledge of the results of the DCCT encourages significant numbers of patients to want to improve glycemic control. Fear of hypoglycemia and, in women, weight gain may prove significant impediments to the clinical implementation of the results of the DCCT.

Effect of tibial attachment location on the healing of the anterior cruciate ligament freeze model

We studied the healing response of a devitalized anterior cruciate ligament to a treatment of initial anterior-posterior joint translation in goats. Devitalization and devascularization were achieved by five successive freeze-thaw cycles. Anterior-posterior translation was surgically altered by an osteotomy of the tibial attachment of the devitalized ligament and its reattachment either in the anatomical position or in a position 5 mm posterior. Six weeks after the first surgery, the same procedure was performed on the contralateral limb, except that the ligament was reattached in the alternate position. Six months after the initial surgery, femur-anterior cruciate ligament-tibia specimens were tested to determine their structural and mechanical material properties. Anatomic ligament placement resulted in reduced anterior-posterior translation (p < 0.05) and greater anterior joint stiffness (p < 0.05). Maximum load (p < 0.05) and ligament stiffness (p < 0.01) also were greater for the anatomically placed anterior cruciate ligaments. The maximum load for anatomically placed ligaments averaged 1.625 +/- 211 N (SEM). The strength of the posteriorly placed anterior cruciate ligament, 895 +/- 164 N was similar to results of historical anterior cruciate autograft reconstructions. Ligament failure occurred near the tibial insertion in the posteriorly placed ligaments more often than in the anatomically placed ligaments (four of five times compared with one of five times). Ligament failure near the tibial insertion occurred with lower mean maximum load than failure at the midsubstance or by bone avulsion (796 compared with 1.592 N: p < 0.05). These data support the hypothesis that ligament laxity is important to the healing and remodeling of anterior cruciate ligament grafts.

The use of an implantable force transducer to measure patellar tendon forces in goats

Patellar tendon (PT) force was measured during activity with an implantable force transducer (IFT) in adult goats. PT force, vertical ground reaction force (VGRF) and the animal's speed were recorded for standing, walking and trotting. Following data collection, animals were euthanized and the IFT calibrated in vitro. Standing PT force averaged 207 N. Maximum PT force was approximately 800 N for walking and 1000 N for trotting and occurred at mid-stance. PT force dropped from 200 N at toe-off to 0 N by mid-swing. For each activity, the PT force increased with increases in VGRF. Maximum in vivo PT stress occurred during trotting and measured 29 MPa. This study demonstrates the IFT's usefulness in measuring tendon force directly.

Epidemiologic evidence for clustering of equine motor neuron disease in the United States

OBJECTIVE

To examine the regional variations in the distribution of equine motor neuron disease (EMND) in the United States and the factors that might explain those variations.

DESIGN

Cluster investigation and case-control study.

SAMPLE POPULATION

The study population consisted of 97 horses with histopathologically confirmed EMND and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base.

PROCEDURE

The total horse population of the United States was divided into 21 regions, and the regional incidence rates of EMND from January 1985 through January 1995 were estimated. Moran's index of spatial autocorrelation was calculated to test for spatial clustering of the disease. The 21 regions were then joined in broader areas according to the similarity of their EMND rates by means of the cluster analysis statistical technique. Finally, the role of potential confounding factors (age at diagnosis, month of diagnosis, breed, and sex) in the present distribution of EMND was assessed, using logistic regression analysis.

RESULTS

Differences in estimated rates across the 21 regions resulted in a strong pattern of spatial clustering of EMND in the United States. The geographic units were grouped into 5 risk regions, with the gradient of EMND incidence rates increasing from the western states (almost 0 cases/1,000,000 horse-years) toward New England (20.78 cases/1,000,000 horse-years). Reported risk factors of EMND (age, breed) and other extraneous factors (sex, month of diagnosis) could not explain the observed geographic variations of disease rates. Nevertheless, there is evidence of some confounding attributable to age and breed.

CONCLUSIONS

Although the mechanism responsible for the clustering of EMND in northeastern states is still unexplained, it is not an epiphenomenon caused by regional differences in the distribution of the factors investigated.

Endothelial lipopigment as an indicator of alpha-tocopherol deficiency in two equine neurodegenerative diseases

Two spontaneous neurodegenerative diseases of the horse, equine motor neuron disease (EMND) and equine degenerative myeloencephalopathy (EDM), have been associated with alpha-tocopherol deficiency, and both were characterized by prominent accumulations of endothelial lipopigment in the small vessels of the spinal cord. These endothelial pigment deposits appear to be reversible. In EMND horses pasture-supplemented for 9 months or more after the progression of weakness and wasting had arrested, there was very little endothelial lipopigment. The origin and the potential effects of these endothelial lipopigment accumulations are discussed.

Factors affecting sensitivity of a transducer for measuring anterior cruciate ligament force

In order to determine the measurements and calibration methods necessary to accurately measure in vivo forces in the anterior cruciate ligament (ACL) of the goat, an in vitro study was conducted to evaluate the effect of several factors that could influence the sensitivity of a transducer implanted within the ligament. Four factors were studied in six specimens: flexion angle [0 degrees, 10 degrees, 30 degrees, 50 degrees, and 70 degrees from full extension (FFE)]; tibial rotation (0 degrees and 10 degrees of internal rotation at 30 degrees, 50 degrees, and 70 degrees flexion FFE); loading rate (cycling frequencies of 0.2, 0.5, 1.0, and 2.0 Hz); and temperature (22 degrees C and 37 degrees C). Anteroposterior tibial displacements were applied to the specimens following tissue resection to isolate the ACL. The resultant ACL force magnitude was measured with a multi-component load cell, and transducer sensitivity was calculated as the slope of the output vs force curve in the linear response region. Transducer sensitivity varied with joint position in each specimen, but there was no consistent trend from specimen to specimen in how the sensitivity changed. As a result, there were no statistically significant mean differences (p > 0.05). There were no significant differences and little variation in sensitivity due to changes in either loading rate or tissue temperature, although the latter produced a voltage offset. The results show that the transducer output with zero force on the ligament must be determined in vivo, after which in vitro calibrations may be conducted at room temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence and risk factors of equine motor neuron disease: an ambidirectional study

We have conducted an ambidirectional study to estimate the incidence of equine motor neuron disease (EMND) in the northeastern US. The clinical and pathological features of EMND are similar to those described in human motor neuron disease. We have also collected data on all EMND cases reported in the US and described the geographic distribution of the disease. To identify factors associated with the risk of EMND, the authors assembled 163 control horses from the population in which cases were identified. The significance of association between the hypothesized factors and the risk of EMND was evaluated using the logistic regression analysis and the risk was estimated using the odds ratio. Seventy-eight horses in North America were diagnosed with EMND between the period of January 1985 and November 1993. Most of the cases were identified in the Northeast of the US and the incidence of EMND appears to be increasing in this area. Factors found to be significantly associated with EMND were breed and the age of the horse. Quarter horses were the only breed with a significantly higher risk of EMND (odds ratio = 2.3). The risk of EMND increased with age, reached a peak around 16 years of age and then declined. The sex of the horse was not associated with the risk of the disease.

Equine motor neuron disease: findings in 28 horses and proposal of a pathophysiological mechanism for the disease

Over a three and one-half year period, 28 adult horses were diagnosed with equine motor neuron disease (EMND). The most commonly identified environmental risk factors for a horse having EMND were absence of grazing for more than a year and provision of poor quality hay. Quarter Horses were 5.4 times more at risk than other breeds but this was thought to be an epiphenomenon related to the frequency of Quarter Horses at boarding stables. Weight loss, excessive recumbency and/or trembling were the first signs noted. Other clinical diagnostic signs included: constant shifting of the weight in the rear limbs, abnormally low head carriage and muscle fasciculations. Excellent to ravenous appetites were present in all cases and marked coprophagia in some cases. Abnormally high serum concentration of muscle-derived enzymes was the only consistent serum chemistry abnormality found. Abnormal glucose absorption, increased cerebrospinal fluid total protein and intrathecal production of IgG were identified in a number of cases. Euthanasia was performed on 5 horses within 4 days of hospital admission, because of inability to stand or respiratory distress, and on 18 horses after the diagnosis had been completed. Five affected horses were maintained for observational purposes for periods of 9 months to over 2 years after the onset of clinical signs. They were given access to pasture and 2 were given supplemental vitamin E as the only therapy. Marked clinical improvement occurred in the 4 more acutely affected horses. Pathological findings, preference of type 1 muscle fibre atrophy and lipopigment accumulation within the capillary endothelium of the spinal cord of all cases, supported the hypothesis of EMND being an oxidative disease.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo forces in the anterior cruciate ligament: direct measurements during walking and trotting in a quadruped

In vivo forces in the anterior cruciate ligament (ACL) were measured in three adult goats during quiet standing and during gait (walking or trotting). A modified pressure transducer (MPT) was implanted within the anteromedial band of the ligament to make direct measurements of ACL force. One or two days following implantation, measurements were made of ACL force, knee joint flexion angle, ground reaction forces, and speed of locomotion. MPT calibration was performed in vitro using anteroposterior displacement tests at six flexion angles. The ACL was loaded during quiet standing (30-61 N) and during the stance phase of gait. Peak ACL forces were achieved within the first 40% of stance, with magnitudes ranging from 63 to 124 N during walking and from 102 to 150 N during trotting. The average ACL force during the stance phase ranged from 34 to 68 N while walking and from 46 to 69 N while trotting. The partial correlations between peak ACL force and speed, and between average ACL force and speed, were both statistically different from zero (p < 0.01). ACL forces dropped to zero during the swing phase in all trials. ACL forces were less than 15 N throughout swing in two of the animals, both of which did not extend their knees during gait beyond 20 degrees from full extension. In the animal which did show knee extension beyond 40 degrees (20 degrees from full extension), ACL loading occurred during late swing. The magnitude of the peak ACL force during late swing was significantly correlated with the extent of knee extension in this animal.

Substance P immunohistochemical study of the sensory innervation of normal subchondral bone in the equine metacarpophalangeal joint

Serial sections of bone and soft tissue from the metacarpophalangeal joints of 2 mature and 2 immature horses were evaluated for substance P immunoreactive sensory nerve fibers. Formalin-fixed specimens were sectioned, either nondemineralized or demineralized with formic acid or EDTA. Rabbit antiserum to substance P (SP) was used in the streptavidin-biotin-peroxidase complex method for immunolocalization of SP antigen, and staining with 3,3'-diaminobenzidine was used for permanent identification of SP fibers. Abundant sensory nerve fibers were identified in the joint capsule, synovial membrane subintimal layers, collateral ligaments, suspensory ligament and distal sesamoidean ligament attachments to the sesamoid bones, and the periarticular periosteal layers. Sparse SP-immunoreactive nerve fibers were found in subchondral bone plates of the metacarpus, proximal first phalanx, and dorsal articular surface of the sesamoid bones. Most SP fibers were associated with blood vessels in the small cancellous spaces and haversian canals of the subchondral bone. The deeper marrow spaces contained increased numbers of SP sensory fibers; a few appeared in small groups and as several SP-immunoreactive fibers in a larger nerve. Cortical bone contained only a few SP fibers in the haversian canals. Substance P fibers were not identified in the osteocytic lacunae, canaliculi, or the bony lamellae of the haversian systems of the subchondral bone plate, and its extension to the metaphyseal and diaphyseal cortical bone. Equine metacarpophalangeal joint soft tissues have an abundant sensory nerve supply, similar to that of other species.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatolytic neuronal degeneration in a six-year-old cairn terrier

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Subclinical lumbar polyradiculopathy, polyneuritis and ganglionitis in aged wild and exotic mammalians

Subclinical lumbar polyradiculopathy was present in the intradural dorsal and ventral nerve rootlets of 19 aged individuals of the following wild and exotic mammalian species: woodrat, raccoon, mink, lynx, reindeer, red deer, musk ox, scimitar-horned oryx, Arabian oryx, hybrid waterbuck, Persian onager, Przewalski's wild horse, Malayan sun bear, Asian elephant, East African river hippopotamus, vervet monkey and rhesus monkey. It was characterized by mild to severe multifocal ballooning of myelin sheaths. Occasionally, ballooned myelin sheaths contained thin strands of myelin and macrophages surrounding distorted axons. Additionally, a mild incidental lymphocytic polyneuritis was present in intradural nerve rootlets of the Malayan sun bear, and a moderate lymphocytic spinal ganglionitis in the East African river hippopotamus.

Neuropeptide distributions in the colon, cecum, and jejunum of the horse

The pelvic flexure portion of the equine large colon is the proposed location of a pacemaker mechanism. This study was conducted to ascertain whether the distribution of certain putative neurotransmitters differs at the pelvic flexure compared to other sampling sites. Tissue samples were collected from the intestinal tracts of six horses. Serial sections from these samples were reacted with primary antisera specific for substance P, vasoactive intestinal polypeptide (VIP), methionine-Enkephalin, and calcitonin gene-related peptide (CGRP). The regional distribution of immunoreactive neuronal elements was uniform for each of the neuropeptides except VIP. Although neurons exhibiting VIP-like immunoreactivity were abundant throughout the colon, they were somewhat more plentiful near the apex of the pelvic flexure and the left dorsal colon. These neurons may participate in the initiation and propagation of the propulsive/retropulsive contraction waves, which emanate from this location and are believed to lend a sphincter-like capacity to the pelvic flexure. The submucosal plexus was replete with neurons with intense substance P and VIP-like reactivity. Reactive fibers left submucosal ganglia to project to the intestinal mucosa, reflecting a possible secretogogic role for these neurons. This role may be especially important for the horse as a hindgut fermenter. There were abundant methionine-Enkephalin and substance P-like reactive varicosities throughout the myenteric plexus, many of which established a pericellular plexus of varicose fibers. The abundance of these varicosities, which may correlate with a high degree of neuronal integration, did not vary regionally. These data may enhance our understanding of both normal colonic peristalsis and motility disorders caused by a depletion of these neuropeptides.

Risk factors associated with equine motor neuron disease: a possible model for human MND

Equine motor neuron disease (EMND), a newly described neurodegenerative disease, bears a striking resemblance to progressive muscular atrophy (PMA) in humans. We present a comparison of the equine and human diseases and the results of a case-control study conducted to identify intrinsic factors associated with EMND. Cases included all horses with a confirmed diagnosis of EMND diagnosed in the United States since 1985 (32 cases). Controls included horses diagnosed with either cervical stenotic myelopathy, equine degenerative myeloencephalopathy, or protozoan myelitis at the Veterinary Teaching Hospital at the College of Veterinary Medicine, Cornell University (153 controls). Logistic regression analysis identified factors associated with the risk of EMND. Risk factors considered were age, sex, and breed of the horse. Most cases of EMND (30 of 32) have been sporadic. There was a breed association with the risk of EMND. Quarter horses were at a high risk for developing EMND (odds ratio [OR] = 12.7; 95% confidence interval, 3.3 to 49.6); thoroughbred horses were at increased risk (OR = 2.9, 0.8 to 10.4). There was also an age association with the risk of EMND. The risk increased with age, peaked at 16 years, and then declined, a pattern similar to that for amyotrophic lateral sclerosis in humans. There was no sex association with the disease. Despite the breed association, equine lymphocyte antigen studies have not revealed a systematic pattern, suggesting that genetic factors influencing susceptibility to EMND may be outside the major histocompatibility complex.

Neuroaxonal dystrophy in a Jack Russell terrier pup resembling human infantile neuroaxonal dystrophy

A 9-week-old Jack Russell terrier with progressive ataxia had histopathological lesions consistent with neuroaxonal dystrophy. Gross observation revealed absence of the septum pellucidum, hypoplasia of the corpus callosum and marked bilateral hydrocephalus. Light microscopy of the CNS revealed extensive axonal swellings principally in the gray matter of the brain stem where the sensory nuclei were most affected. Ultrastructurally, spheroids were identified as axonal terminals and probably dystrophic boutons; they were characterized by accumulations of membrane bound bodies. Clinical and morphological findings are similar to those identified in human infantile neuroaxonal dystrophy (Seitelberger's disease).

A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model

Similar-sized patellar tendon autografts and fresh-frozen allografts were used to reconstruct the anterior cruciate ligament of one knee in 40 female goats. Evaluations of the reconstructions and contralateral controls at the 6-week and 6-month postoperative periods included anterior-posterior translation, mechanical properties determined during tensile failure tests, measurement of cross-sectional area, histology, collagen fibril size and area distribution, and associated articular cartilage degenerative changes. Six months after anterior cruciate ligament reconstruction, the autografts demonstrated a smaller increase in anterior-posterior displacement, values of maximum force to failure two times greater, a significant increase in cross-sectional area, a more rapid loss of large-diameter collagen fibrils, and an increased density and number of small-diameter collagen fibrils compared to the allografts. Clinical significance. More surgeons are allowing their patients to return to running and sports 6 months after anterior cruciate ligament reconstruction. While the structural and material properties of autografts and allografts at time zero are similar, in the goat model during the first 6 months they differ. The allografts demonstrate a greater decrease in their implantation structural properties, a slower rate of biologic incorporation, and the prolonged presence of an inflammatory response. At 6 months the autograft demonstrates a more robust biologic response, improved stability, and increased strength to failure values.

Eosinophilic cytoplasmic inclusions in sporadic equine motor neuron disease: an electron microscopic study

Equine motor neuron disease (EMND) is a sporadic, progressive neurodegenerative disorder that has been identified recently in horses of different breeds in North America. The cause is unknown. Pathologic changes which occur in spinal and certain brain stem motor neurons include chromatolysis, swelling, neurofilamentous accumulation, and development of eosinophilic cytoplasmic inclusions. Punctate eosinophilic inclusions, the type usually encountered in degenerating neurons, resembled Bunina bodies at the light microscopic level, but differed in their ultrastructural composition. These and less common but larger juxtanuclear inclusions appeared to be aggregated vesicular residues of membranous organelle degradation. The third kind of eosinophilic inclusion was a marginated derivative of endoplasmic reticulum and consisted of large membrane-bound accumulations of finely granular material. It was concluded that, although the distribution and nature of the lesions in EMND appeared similar to those of human motor neuron disease, none of the equine eosinophilic inclusions duplicated the ultrastructure of Bunina bodies.

Motor neuron degeneration in a horse

A 9-year-old Quarter Horse mare was examined because of progressive weight loss, weakness, muscle atrophy and tremors, and behavioral change. Selenium and glutathione peroxidase assays, blood lead analysis, erythrocyte transketolase analysis, pseudorabies and Borrelia burgdorferi serology, electromyography, and CSF analysis were performed. Motor neuron degeneration was diagnosed by microscopic examination of neural tissues. The cause of the disease was not substantiated, but several possibilities were excluded via diagnostic testing. Diagnosis of motor neuron degeneration in horses may be made from an accurate history, thorough neurologic examination, and ancillary testing. In particular, antemortem diagnosis may be based on finding scattered angular atrophy of predominantly type-1 or of type-1 and -2 skeletal muscle fibers in frozen sections of muscle biopsy specimens.

Location-dependent variations in the material properties of the anterior cruciate ligament

Our recent anterior drawer studies in human cadaveric knees [Guan and Butler, Adv. Bioengng 17, 5 (1990); Guan et al., Trans. orthop. Res. Soc. 16, 589 (1991)] have suggested that anterior bundles of the anterior cruciate ligament (ACL) develop higher load-related material properties than posterior bundles. This was confirmed when we reevaluated the axial failure data for these bundle-bone specimens from an earlier study [Butler et al., J. Biomechanics 19, 425-432 (1986)]. The purpose of this study was to determine, in a larger data set, if anteromedial and anterolateral bundles of the anterior cruciate ligament exhibit significantly larger load-related material properties than the posterior ligament bundles. Seven ACL-bone units from seven donors (the three tissues from the original study plus four new ones) were subdivided into three subunits, preserving the bone insertions. The subunits were failed in tension at a constant strain rate (100% s-1) and four material properties were compared within and between donors. The anterior bundles developed significantly larger moduli, maximum stresses, and strain energy densities to maximum stress than the posterior subunits. Moduli for the anterior vs posterior subunits averaged 284 MPa vs 155 MPa, maximum stresses averaged 38 MPa vs 15 MPa, and strain energy densities averaged 2.7 N m cc-1 vs 1.1 N m cc-1, respectively. No significant differences were found, however, among strains to maximum stress or between any of the other properties for the two anterior subunits. These results are important to the design of ligament replacements and suggest new experiments designed to distinguish in vivo force levels in these ACL bands, a possible reason for the material differences.

Tibetan terrier model of canine ceroid lipofuscinosis

Over a 10-year period, we have studied the Tibetan terrier's visual electrophysiology, light and electron microscopic (EM) retinal characteristics of a slowly evolving inherited ceroid lipofuscinosis (CL). The retinal degeneration with CL inclusions (rdi) in the inner nuclear layer (bipolar cells) and nerve fiber layer (ganglion cells) has been called "rdi" to differentiate the visual abnormality from typical early retinal degeneration (erd) reported also in the Tibetan terrier. The unique "rdi" electroretinogram (ERG) gives a predominant P III wave at age 7 weeks but becomes more characteristically depressed in all phases over several years. Nyctalopia is the only functional abnormality for the first 5 to 6 year of life. Signs are remarkably few considering the pathology. Microscopic studies of the retina show accumulations, increasing with age, of autofluorescent dense inclusion particles which stain intensely by Luxol fast blue, PAS, and acid-fast procedures. Ultrastructural studies of the retina show the dense particles to be lamellar membranes repeating every 2 to 4 nm, consistent with ceroid lipofuscin. The inner retinal layers were always the target layer to be affected first and most severely. The ganglion cells were most frequently involved. The photoreceptors eventually degenerated but relatively few particles were found in this layer. The cytosomes in the cerebral cortex and brainstem neurons resemble lipofuscin, containing granular, lamellar, and globular components. Different pigment bodies were present in the cerebellar Purkinje cells. Neuronal loss which was moderate in the cerebellum and mild in the cerebrum was accompanied by astrogliosis and a striking presence of macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Sarcocystis neurona from a thoroughbred with equine protozoal myeloencephalitis

Morphological information is presented for syntype material of the etiologic agent of equine protozoal myeloencephalitis, Sarcocystis neurona. A clinical description of the horse from which the organism was isolated and the methodology used to immunosuppress the horse in an attempt to increase parasite numbers are also given. The description includes microscopic details observed both with light and transmission electron microscopy. Mainly stages from tissue are illustrated, but information is also presented on the development of the organism after inoculation onto monolayers of bovine monocytes. It is believed that the large numbers of organisms observed in this horse were due to its having not received prior treatment with trimethoprimsulphonamide and the large amounts of corticosteroids that were administered in order to facilitate isolation of the pathogen.

Equine myenteric plexus with special reference to the pelvic flexure pacemaker

Sellers et al. (1979, Am. J. Phys., 237: E457-E464) proposed a pelvic flexure pacemaker mechanism to account for the bidirectional contraction waves needed to both retain ingesta within the right ventral colon for cellulose digestion and terminal fermentation and to transport the digesta distad once the process has been completed. To corroborate the presence of a pelvic flexure pacemaker, we prepared whole mount samples of the tunica muscularis from 23 horses at ten sites along the large colon, cecum and jejunum. Following smooth muscle enzymatic digestion, somata of the myenteric plexus were stained with an RNA-specific agent, Cuprolinic blue. These somata were quantified at each site to establish any regional variations in neuronal density. Results indicated an increased neuronal density at the level of the pelvic flexure, especially in the region of the left dorsal colon. The increased neuronal density at the left dorsal colon compared to the other sampling sites was statistically significant (Wilcoxon signed rank test, P less than .01 at each sampling site). There was remarkable size variation (from 10-60 microns) among neurons at the individual sampling sites. However, no statistically significant size discrepancy existed between sampling sites (Friedman's rank test, P = .10). The 23 horses ranged from 6 months to 15 years of age. No age-related differences in neuronal density was discovered (Kruskal-Wallis ANOVA test, P greater than .05). Neuronal densities did not vary on the basis of sex (Wilcoxon signed pairs test, P greater than .05).(ABSTRACT TRUNCATED AT 250 WORDS)