Erik J. Olson

Histologic and Immunohistochemical Characteristics of Failed Articular Cartilage Resurfacing Procedures for Osteochondritis of the Knee A Case Series

Background The histologic appearance of the repair tissue after articular cartilage resurfacing procedures in humans is not well documented. Hypothesis The histologic and immunohistochemical appearance of the repair tissues in failed articular cartilage resurfacing procedures will be similar, regardless of the procedure that was done, and will not resemble normal articular cartilage. Study Design Case series; Level of evidence, 4. Methods Graft tissue from 10 patients who underwent an autologous chondrocyte implantation (n = 6), microfracture (n = 3), or periosteal transplantation (n = 1) procedure to treat symptomatic osteochondritis dissecans of the medial femoral condyle was processed for histologic examination after failure of the articular cartilage resurfacing procedure. Serial sections from all slabs were stained with hematoxylin and eosin and toluidine blue and were immunostained using antibodies directed against types I, II, and X collagen. Results Specimens from all 3 types of repair procedures were composed primarily of fibrous connective tissue and fibrocartilage. None of the sections stained positively for type X collagen. All 10 cases stained positively for type I collagen (range, 7%–97% of tissue area). Staining for type II collagen was positive in 4 of 6 autologous chondrocyte implantation cases, 3 of 3 microfracture cases, and the periosteal transplant case (range, 2%–65% of tissue area). In 8 of 10 cases, the percentage of the section area exhibiting positive staining for type I collagen was higher than for type II collagen (6 of 6 autologous chondrocyte implantation; 1 of 3 microfracture; 1 periosteal transplant). Conclusion The histologic appearance of the repair tissue of 3 different failed articular cartilage resurfacing procedures was similar and did not resemble normal articular cartilage.

Cooperia punctata: Effect on cattle productivity?

Cooperia spp. have become the most prevalent parasites in United States cow/calf operations as observed in the USDA NAHMS (National Animal Health Monitoring System) Beef Cow/Calf survey in 2008. This is at least in part due to the widespread use of macrocyclic lactones that have recently been shown to have a reduced activity against these parasites. The effects of Cooperia spp. on cattle productivity are largely unknown. This study was conducted to assess their effect upon cattle housed under conditions found in American feedlots. Two hundred yearling calves (average weight 460 lb/209 kg) were acquired from northwestern Arkansas and northeastern Oklahoma and were vaccinated and dewormed upon arrival at the feedlot. Animals were comingled and preconditioned for approximately one month, and were fed a standard growing ration throughout the study. Calves were randomly divided into two groups (n=80, infected and control) and each group was further divided into two replicate pens (n=40). Calves from the two infected pens were orally inoculated with a gavage of 1 × 10(5) and 0.825 × 10(5) infective larvae of a recent isolate of Cooperia punctata on day 0 and 14, respectively, with the two control pens receiving a similar volume of tap water. Data collected included biweekly fecal egg counts, daily individual feed consumption and weight gain over the 60-day test period. The presence of C. punctata (>99% of recovered worms) was confirmed by necropsy and recovery from the small intestine on days 35 and 60 post infection (PI) in a subset of animals. Egg counts were positive by day 14 PI and remained at numbers similar to values seen in field studies. The control group gained weight 7.5% more rapidly (p=0.02) than infected animals (3.24 lb/1.47 kg per day vs. 3.0 lb/1.36 kg per day, respectively). The Cooperia-infected calves also consumed 1.5 lb (0.68 kg) less dry feed per day than the control animals (p=0.02). These data suggest that C. punctata has a deleterious effect on both appetite and nutrient uptake or utilization. At necropsy (days 35 and 60), the draining mesenteric lymph nodes of infected animals were increased in size and the small intestinal mucosa was thickened and covered with a thick layer of mucus in the infected animals. The most prominent histological changes in the Cooperia- infected animals included a moderate increase in the number of intraepithelial lymphocytes and globule leukocytes, as well as aggregates of eosinophils within the lower lamina propria. The only significant difference was an increase in the goblet cell density at day 60. Anthelmintic sensitivity/resistance of the Cooperia isolate used was determined by treatment of one pen of infected calves with a macrocyclic lactone and the other pen with a benzimidazole at the completion of the study. The macrocyclic lactone treatment (n=40) did not remove the parasites (FECRT=8.8%), while treatment with a benzimidazole was very effective (FECRT=98.1%). This study demonstrated that C. punctata has a significant effect on cattle productivity, both reduced weight gain and decreased feed intake compared to controls.

Abundance and Distribution of Macroinvertebrates in Relation to Macrophyte Communities in a Prairie Marsh, Swan Lake, Minnesota

ABSTRACT We compared the macroinvertebrate communities among vegetation types in Swan Lake, a large prairie marsh in south-central Minnesota. Activity traps and sweep nets were used to sample macroinvertebrates during the summer months of 1992 and 1993. Twenty-four sites on the lake were sampled along six established transects. Each site was located in one of four different habitats, including three major macrophyte communities: Typha angustifolia, Scirpus acutus, Potamogeton spp., and an open water site having little or no vegetation. The diversity, relative abundance, and biomass of the invertebrates collected from each vegetation type were compared to assess which type of vegetation supported the greatest numbers and most diverse invertebrate fauna. A total of 16 orders, 46 families and 93 genera were identified. Results suggest that the open water sites produced the largest number of organisms, whereas the Typha sites produced the greatest total biomass of invertebrates. Nine orders showed significant...

An in vivo injury model of posterolateral knee instability.

Background Posterolateral knee instability is a difficult clinical problem to diagnose and treat. To best evaluate its natural history and the effects of interventional treatments, it is important to develop an in vivo model in an attempt to validate human cadaveric and clinical observational studies. Purpose To develop an in vivo model of posterolateral knee instability in the rabbit and to determine the natural history of untreated posterolateral knee injuries at 6 months postoperatively. Study Design Controlled laboratory study. Methods The fibular collateral ligament and popliteus tendon were surgically transected in 1 knee in each of 10 skeletally mature New Zealand White rabbits, with the contralateral knee serving as a control knee. At 6 months postoperatively, the rabbits were euthanized, the knees were removed, and biomechanical testing of knee joint stability was performed. After biomechanical testing, histological sections of each proximal tibia and distal femur were evaluated, and each proximal tibia was graded using an osteoarthritis grading scheme. Results Biomechanical testing revealed a statistically significant difference in amount of rotation in the operated knees compared with the unoperated control knees to varus moments at 30°, 60°, and 90° and to external rotation torques at 30° and 60°. Morphological analysis revealed no significant difference in lesions of osteoarthritis in the medial compartment of the operated knees compared with the unoperated knees. Conclusions Although the presence of posterolateral knee instability was validated 6 months after surgery in this model, the authors did not identify significant differences in lesions of osteoarthritis in the operated knees compared with the unoperated control knees. Clinical Significance This study confirms that posterolateral knee instability can be created in an animal model. It also recapitulates the clinical observation in humans that untreated posterolateral knee injuries do not heal. Similar to animal models of medial collateral ligament sectioning, further studies to validate a posterolateral instability knee model may lead to interventional studies to determine the best way to treat this complex knee instability pattern.

Putative Metronidazole Neurotoxicosis in a Cat

A presumptive case of metronidazole toxicity in a 3.4-kg adult cat is described. The cat had been treated for suspected inflammatory bowel disease with an anti-inflammatory dose of prednisone and metronidazole (73.5-147 mg/kg PO q24h) for approximately 40 days prior to presentation. Clinical signs were primarily related to the central nervous system, including acute tetraparesis, unresponsiveness, tremors, and vocalization. The patient was euthanatized after 12 days of supportive care. Necropsy revealed no significant macroscopic lesions. Histologic evaluation revealed multifocal, fairly well-demarcated foci of necrosis in the brainstem, extending from the diencephalon to the medulla oblongata. To our knowledge, this is the first report to document histologic lesions associated with metronidazole administration in a cat.

Pulmonary embolism without deep venous thrombosis: De novo or missed deep venous thrombosis?

BACKGROUND Pulmonary embolus (PE) is thought to arise from a deep venous thrombosis (DVT). Recent data suggest that PE can present without DVT, inferring that PE can originate de novo (DNPE). We examined the relationship between DVT and PE in trauma patients screened for DVT with duplex sonography (DS). We sought to validate the incidence of PE without evidence of DVT and to examine the clinical significance of this entity. METHODS We reviewed the medical records of all trauma patients from July 2006 to December 2011 with PE who also had serial surveillance DS (groin to ankle). Demographics, severity of injury, interventions, signs and symptoms of PE, as well as chest computerized tomography findings were collected. Patients with no DS evidence of DVT either before or within 48 hours of PE diagnosis (DNPE) were compared with those with DVT (PE + DVT). RESULTS Of 11,330 patients evaluated by the trauma service, 2,881 patients received at least one DS. PE occurred in 31 of these patients (1.08%): 19 (61%) were DNPE, and 12 (39%) were PE + DVT. Compared with patients with PE + DVT, patients with DNPE were significantly younger and had more rib fractures, pulmonary contusions, infections, pulmonary symptoms, and peripherally located PEs on computerized tomography. CONCLUSION This is the first report of the clinical course of DNPE without embolic origin in a population with comprehensive duplex surveillance. In our series, DNPE seems to be more prevalent after trauma, to be clinically distinct from PE following DVT, and to likely represent a local response to injury or inflammation; however, further research is warranted to fully understand the pathophysiology of DNPE. LEVEL OF EVIDENCE Care management study, level III.

Systemic blastomycosis in a horse

Progressive multisystemic disease caused by Blastomyces dermatitidis was diagnosed in a 17-year-old Quarter horse broodmare. The mare had been treated unsuccessfully with antibiotics for mastitis 3 months postpartum. The disease progressed to exudative cutaneous lesions affecting the ventrum, pectoral region, and limbs accompanied by weight loss across several months. Yeast bodies were observed in swabs of the cutaneous exudate, suggesting a clinical diagnosis of blastomycosis. Following referral, pleural effusion, cavitated lung lesions, and hyperproteinemia were identified, and the mare was euthanized because of poor prognosis. Necropsy revealed extensive pyogranulomas in the mammary gland, skin, subcutaneous tissues, and lungs, accompanied by thrombi in major blood vessels of the lungs and hind limbs. Histologically, pyogranulomatous inflammation was evident in many tissues, and fungal organisms were seen in sections of mammary gland, skin, subcutis, pericardium, and lung. Blastomyces dermatitidis was cultured from mammary tissue, lungs, lymph node, and an inguinal abscess. Although blastomycosis is endemic in the area of origin of the mare in northwestern Wisconsin, the disease is extremely rare in horses and hence easily misdiagnosed. Unique features of this case included the extent of mammary gland involvement and the presence of thrombi in multiple sites.

Sarcocystis sp.-Associated Meningoencephalitis in a Bald Eagle (Haliaeetus Leucocephalus)

Protozoal meningoencephalitis is uncommon in raptors. An adult female bald eagle (Haliaeetus leucocephalus) was euthanized after several months of treatment for progressive neurologic signs. The predominant histologic lesion was lymphoplasmacytic and histiocytic meningoencephalitis involving the cerebrum and cerebellum. There was a marked segmental loss of granular cells and Purkinje cells, as well as segmental atrophy of the molecular layer in the cerebellum. Protozoal merozoites and schizonts were observed in the gray matter of the cerebellum. Ultrastructurally, the merozoites were classified as a species of Sarcocystis due to the lack of rhoptries. Immunohistochemistry of the agent revealed a positive reaction for Sarcocystis neurona, while sections were negative for Toxoplasma gondii and Neospora caninum. Sarcocystis sp. infection should be considered as a differential diagnosis in bald eagles with chronic neurologic disease.

Isolation of an adenovirus and an adeno-associated virus from goat kids with enteritis

A dairy goat operation in Minnesota experienced a sudden, markedly increased mortality among its neonatal goats. Approximately 60 of 130 kids (46%) died. The animals had diarrhea and dyspnea of 1–2 days duration before death. Necropsy of 4 goat kids revealed marked, acute, catarrhal enteritis and fibrinous pleuropneumonia. Mannheimia haemolytica was isolated from the lungs. Basophilic inclusion bodies filling the entire nucleus were present in enterocytes of the ileum of 3 goats. Adenoviral particles were detected in the feces by electron microscopy and adenovirus was subsequently isolated from the intestinal content together with a parvo-like virus (dependovirus). Morphology, physicochemical characteristics, and neutralization tests indicated that the adenovirus resembled ovine adenovirus-2 (OAdV-2). However, the PstI restriction endonuclease pattern produced by the goat adenovirus was distinct from that of OAdV-2. This is the first report of enteritis in goats with an adenovirus antigenically related to OAdV-2 and with a parvo-like dependovirus.

Osteosarcoma at the site of a triple pelvic osteotomy in a dog.

An osteosarcoma (OSA) involving the right pelvis was diagnosed in a 12-year-old golden retriever 11 years after triple pelvic osteotomy (TPO) surgery. The dog was presented with a 12-week history of nonweight-bearing lameness of the right hind limb. Radiographs demonstrated an aggressive bone lesion of the right ilium with profound periosteal proliferation and punctate lysis that extended along the ilium caudally and into the right ischium, with its epicenter at the level of the right TPO plate. Necropsy revealed that the entire right hemipelvis, especially the ischium, was markedly thickened and firm with irregular margins. Histopathology was consistent with a diagnosis of OSA.