Evaluation of the Leeds-Keio Synthetic Replacement for the Cranial Cruciate Ligament in Dogs: An Experimental Study

Eight conditioned research dogs, whose body weight was between 25 and 30 kg, had unilateral implantation of a Leeds-Keio (LK) synthetic implant (Dacron polyester) immediately after severance and removal of the cranial cruciate ligament (CCL). A rectangular- shaped autograft, composed of fascia lata, was placed within the LK implant in four of the eight dogs; the other four dogs received the LK implant only. Modified Robert Jones bandages were placed on the limbs that had been operated upon; the bandages were left in place for 48 hours. After that time the limbs were not splinted. The dogs were confined to 1.5 m X 3 m kennels, with twice daily leash walks for the duration of the study. Although the joints that received the LK implants were stable immediately after the operation, they all developed progressive effusion, crepitation and instability accompanied by clinically apparent lameness. All of the dogs were euthanatized three months after the operations. Gross examination of the eight joints that had been operated upon confirmed the presence of degenerative joint disease. Three of the eight dogs had “bucket handle” type tears of their medial meniscus in the joints with the LK implant, and the medial menisci in the other five stifle joints that received LK implants had a fibrillated surface texture. Five of the eight LK implants had either ruptured completely or were stretched and frayed to the point where mechanical testing was not justified. Mean breaking strength of the 3 intact LK implants was 6.6% of the contralateral, control CCL. Ingrowth of fibrous tissue into the LK implants was minimal. The synovium from all joints with LK implants had moderate to severely increased cellularity within the synovial villi and supporting stroma consisting predominantly of lymphocytes, plasma cells and macrophages. Multinucleated giant cells formed aggregates around irregular shaped strands of particulate material which was translucent and refractive. Under polarized light, these particles were bright yellow to green consistent with Dacron particles. It was concluded that the LK implant, as implanted in this study, was not a satisfactory replacement for the CCL in dogs.

The Leeds-Keio synthetic replacement for the canine cranial cruciate ligament was implanted in eight dogs. All eight dogs developed progressive instability and secondary degenerative joint disease over a period of three months after the operation. It was concluded that the Leeds-Keio ligament, as implanted in this study, is not satisfactory for use in dogs.

Bacteriocin biosynthesis contributes to the anti-inflammatory capacities of probiotic Lactobacillus plantarum

Plantaricin EF (PlnEF) is a class IIb bacteriocin produced by Lactobacillus plantarum. We compared L. plantarum NCIMB8826 and LM0419, a plnEFI deletion mutant of that strain lacking plnEF and the gene for the cognate immunity protein plnI, in a 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced mouse model of acute inflammatory bowel disease. Mice fed either L. plantarum NCIMB8826 or LM0419 were not protected against TNBS according to either disease activity or histology (Ameho) scores. Mice consuming NCIMB8826 exhibited intermediate (non-significant) levels of colonic tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) that ranged between the TNBS-treated animals and healthy controls. By comparison, TNF-α and IL-6 quantities were elevated in mice given L. plantarum LM0419 and equivalent to mice given TNBS alone. Both strains survived digestive tract transit in equal numbers and did not result in global changes to the bacterial composition in the intestine according to 16S rRNA gene sequencing either prior to or after TNBS administration. Examination of intestinal taxa showed that mice consuming wild-type L. plantarum, but not LM0419 contained lower proportions of Mucispirillum (Deferribacteres phylum) in the faeces prior to TNBS administration and Parabacteroides (Bacteroidetes phylum) in the caecum after disease induction. Parabacteroides also positively correlated with disease activity and histology scores. These findings suggest a role for PlnEFI production by L. plantarum in benefiting digestive tract health.

A potential role for indoleamine 2,3-dioxygenase (IDO) in Rhodococcus equi infection

Rhodococcus equi is a facultative intracellular bacterial pathogen of foals and immunocompromised humans that infects and proliferates within host macrophages and dendritic cells (DC). Indoleamine 2,3-dioxygenase (IDO), the initial enzyme in the tryptophan catabolism pathway, is upregulated in R. equi infected equine monocyte-derived DC and alveolar macrophages. Tryptophan requirement of R. equi for extracellular and intracellular growth was assessed. Growth of R. equi in minimal media did not require tryptophan and pharmacologic inhibition of IDO had no effect on intracellular proliferation of R. equi in equine alveolar macrophages. To investigate an immune-regulatory role for INDO in R. equi infection, IDO(-/-) (B6.129-(Indotm1Alm)/J) (n=22) and strain matched control (C57BL/6J) (n=20) mice were infected with R. equi by intraperitoneal injection, for 3 and 6 days. There was no difference in bacterial counts in liver or spleen between the two groups. Histological sections of liver and spleen were assigned inflammation scores and RT-PCR for interferon-gamma (IFNγ), tumor necrosis factor-alpha (TNFα), IL-4, IL-6, IL-10, IL-12, IL-23, forkhead box P3 (FoxP3), and transforming growth factor-beta (TGFβ) was performed on liver and spleen. Liver tissue of IDO(-/-) had higher inflammation scores at 6 days post-infection (PI) (P=0.05) and had decreased expression of TGFβ at 3 days PI (P=0.01), and FOXP3 at 3 days (P=0.02) and 6 days (P=0.03) compared to control mice. Immunostaining for FOXP3 showed lower numbers of FOXP3+ regulatory T cells in liver of IDO(-/-) mice 6 days PI. Prolonged inflammation in the liver tissue of IDO(-/-) mice corresponded with lower expression of FOXP3 and TGFβ in that tissue, and also with lower numbers of FOXP3+ regulatory T cells. We conclude that IDO expression by activated macrophages and DC plays a role in dampening the inflammatory response to R. equi infection in mice.

Reduced expression of cyclin-dependent kinase inhibitor p27Kip1 in feline lymphoma

Expression of p27Kip1 was identified in feline lymphoid tissues by immunohistochemistry. In normal lymphoid tissues, p27Kip1 was detected as a distinct nuclear stain in lymphocytes of the follicular mantle zone and interfollicular small lymphocytes, whereas activated lymphoblasts in the germinal center were negative. Lymphoid hyperplasia was similarly immunolabeled but with an expanded mantle zone and marginal zone of p27Kip1-reactive lymphocytes. Both T- and B-cell lymphomas lacked p27Kip1 immunolabel and were determined to be proliferative based on immunohistochemical detection of the Ki-67 antigen. Scattered p27Kip1-immunolabeled lymphocytes were detected throughout the lamina propria of most specimens characterized as lymphoplasmacytic enteritis. The results of this study suggest that the antiproliferative effect of the cell cycle regulator p27Kip1 is abrogated in feline lymphoma, presumably allowing cells to bypass the G1-S checkpoint of the cell cycle.

Particulate dermal matrix as an injectable soft tissue replacement material

Products currently used as injectable soft tissue replacement materials in the dermatologic, plastic and reconstructive, and urological fields exhibit several shortfalls including reactivity, migration, rapid degradation, and necessity of a donor site. This study examines the feasibility of providing a particulate acellular human dermal matrix for injection as a soft tissue replacement material that addresses many of these issues. Animal feasibility studies tested differences in implant performance related to processing techniques, matrix concentration, and volume of the collagen matrix to be injected. Results demonstrated that processing techniques that involve shearing and tearing of the dermal collagen matrix resulted in frayed and damaged collagen bundles and led to rapid resorption or loss of the implant, when injected subcutaneously in a rat model. Processing the collagen matrix in liquid nitrogen resulted in less damage to the collagen matrix and exhibited longer persistence, when compared to the damaged collagen matrix. This particulate matrix also exhibits rapid repopulation by host cells that should enhance revascularization and remodeling. The particulate nature of this processed dermal matrix allows for easy delivery of concentrations up to 330 mg/mL, which exceeds that of other currently used products. This increased concentration should allow for decreased need of "overcorrection" and repeated injections.

Pathologic changes in grossly normal menisci in dogs with rupture of the cranial cruciate ligament

OBJECTIVE

To determine whether histopathologic changes are detectable in grossly normal medial menisci from dogs with rupture of the cranial cruciate ligament (CCL).

DESIGN

Case series.

SAMPLE POPULATION

40 medial menisci from dogs with rupture of the CCL and 20 medial menisci from control dogs without stifle joint disease.

PROCEDURE

Data evaluated included age, duration of clinical signs, and whether rupture of the CCL was complete or incomplete. Three groups (n = 20/group) were also compared on the basis of 5 histologic criteria; group-1 menisci appeared grossly normal and were obtained from dogs with naturally occurring rupture of the CCL, group-2 menisci were grossly abnormal and were also obtained from dogs with naturally occurring CCL ruptures, and group-3 menisci were collected at postmortem from dogs without stifle joint disease that were of similar age and weight as dogs in groups 1 and 2.

RESULTS

Group-2 menisci were significantly different from group-1 and -3 menisci in all histologic criteria. Group-1 menisci were significantly different from control menisci in only 1 of the 5 histologic criteria (cartilage differentiation). Dogs that were > or =3 years old had significantly more surface cellularity than did dogs that were < 3 years old. A significant difference was not detected between groups 1 and 2 with regard to completeness of rupture.

CONCLUSIONS AND CLINICAL RELEVANCE

Histologic changes in meniscal cartilage correlate with gross appearance of the cartilage at time of surgery for rupture of the CCL. On the basis of minimal histologic changes, routine removal of grossly normal menisci does not appear to be warranted.

Prognostic factors and patterns of treatment failure in dogs with unresectable differentiated thyroid carcinomas treated with megavoltage irradiation

OBJECTIVE

To determine quality and duration of progression-free survival (PFS) time in dogs with unresectable thyroid carcinomas treated with definitive megavoltage irradiation and analyze prognostic factors of PFS and patterns of failure (local recurrence vs metastasis).

DESIGN

Prospective clinical trial.

ANIMALS

25 dogs with locally advanced thyroid carcinomas and no evidence of metastasis.

PROCEDURE

Dogs were treated with 48 Gy during 4 weeks on an alternate-day schedule of 4 Gy/fraction.

RESULTS

Irradiation was safe and effective for treatment of large unresectable thyroid carcinomas. Progression-free survival rates were 80% at 1 year and 72% at 3 years. Time to maximum tumor size reduction ranged from 8 to 22 months. Factors affecting PFS were not found. Twenty-eight percent (7/25) of dogs developed metastasis. Dogs with bilateral tumors had 16 times the risk of developing metastases, compared with dogs with a single tumor. Dogs with no evidence of tumor progression had 15 times less risk of developing metastases. Radiation-induced hypothyroidism was suspected in 2 dogs 13 and 29 months after irradiation.

CONCLUSIONS AND CLINICAL RELEVANCE

Irradiation is effective for local control of thyroid tumors, despite their slow regression rate. Results provided evidence that local tumor control affects metastatic outcome in dogs with thyroid carcinomas and is a strong basis for the development of new approaches that include irradiation in the management of dogs with advanced thyroid carcinomas. Improvements in local tumor control alone may be insufficient to improve survival times because of the high risk of metastatic spread before an initial diagnosis is made, which warrants initiation of early systemic treatment.

Acellular human dermis promotes cultured keratinocyte engraftment

In full-thickness skin injury, loss of dermis may result in compromised wound repair, including contracture, hypertrophic scarring, and wound breakdown. This report examines the effect of an acellular dermal matrix on in vivo skin repair. Human keratinocytes cultured onto a synthetic hydrophilic dressing were applied with (N = 9) and without (N = 11) an acellular dermal matrix to full-thickness skin defects on athymic mice. Host cells progressively repopulated the acellular dermal component of the grafts. All animals with dermal matrix revealed fully differentiated epidermis by postoperative day 21. Human keratinocytes persisted in all animals grafted with dermal matrix, compared to only 63.6% of those animals without a dermal component. Planimetric analysis revealed significantly reduced wound contraction (p = 0.016) in animals receiving the dermal matrix. Histologic, immunohistochemical, and electron microscopic analyses also were performed. These studies suggest that an acellular dermal matrix can effectively direct regeneration of normal skin morphology.

Dietary modulation of methotrexate-induced enteritis in cats

OBJECTIVE

To determine effects of purified and dry expanded (complex) diets on intestinal structure and function in healthy cats and in a feline model of methotrexate-induced enteritis.

ANIMALS

19 adult specific-pathogen-free cats.

PROCEDURE

Cats were randomized in groups to receive a purified diet intragastrically or a complex diet orally to meet their daily metabolizable energy requirements. After 21 days, cats received either methotrexate (MTX; 10 mg/kg of body weight, i.v., n = 12) or saline solution i.v. (n = 7), and were anesthetized 72 hours later. Celiotomy was performed for aseptic removal of mesenteric lymph nodes, full-thickness biopsy of the gastrointestinal tract, and collection of aortic and portal venous blood samples for determination of arteriovenous amino acid concentrations across the intestine.

RESULTS

MTX was associated with severe enterotoxicosis in cats receiving the purified diet, as manifested by diarrhea (4 of 6 cats) and vomiting (2 of 6 cats). One cat receiving the complex diet developed mild diarrhea, and none of these cats vomited. The purified diet was associated with marked villus blunting in the proximal and distal portions of the duodenum and increased bacterial translocation (3 of 6 cats), whereas none of the cats in the complex diet group developed bacterial translocation after MTX administration. For the cats given saline solution, bacterial translocation occurred in 1 of 4 cats receiving the complex diet versus 2 of 3 cats receiving the purified diet.

CONCLUSIONS

Feeding of a complex diet containing intact protein as the nitrogen source abrogated the proximal small intestinal atrophy and bacterial translocation associated with feeding an amino acid-based purified diet.

CLINICAL RELEVANCE

Use of purified diets containing free amino acids as the only nitrogen source cannot be endorsed in human and animal cancer patients receiving systemic chemotherapy.

Analysis of prognostic factors and patterns of failure in dogs with periodontal tumors treated with megavoltage irradiation

OBJECTIVE

To determine quality and duration of progression-free survival (PFS) time in dogs with periodontal tumors after definitive megavoltage irradiation and to analyze prognostic factors for PFS time and patterns of treatment failure.

DESIGN

Prospective clinical trial.

ANIMALS

47 dogs with acanthomatous, fibromatous, or ossifying epulis.

PROCEDURE

Dogs were treated with 48 Gy over 4 weeks on an alternate-day schedule of 4 Gy/fraction. Multivariate analysis was done by use of Cox's proportional hazards regression model to determine prognostic factors for PFS time.

RESULTS

The only independent prognostic factor for PFS time was tumor T stage. Pattern of local tumor recurrence (marginal vs infield regrowth) was independent of clinical stage, tumor location, and site. In 4% of the dogs, severe acute radiation reactions in the final week of treatment resulted in treatment discontinuation. In 6.4% of the dogs, chronic radiation reactions included bone necrosis.

CLINICAL IMPLICATIONS

Irradiation was a safe and effective treatment of small (T1 and T2 stage) periodontal tumors. The usefulness of the radiation protocol in this study is limited in dogs with large (T3) tumors, particularly those located in the caudal half of the oral cavity, because of poor results and high risk of acute radiation toxicoses.

A computer-controlled, continuously circulating, hot irrigating system for endometrial ablation

OBJECTIVE

This study evaluated the efficacy of a computer-controlled thermal catheter system to ablate the endometrium by use of 5 to 15 ml of hot saline solution.

STUDY DESIGN

Five in vivo sheep uteri and 32 freshly excised human uteri were studied by inserting a self-contained heater catheter equipped with thermocouples and circulating hot saline solution for 15 minutes within the uteri at various temperature settings ranging from 60 degrees C to 80 degrees C. The uteri were grossly examined and microscopically evaluated by hematoxylin and eosin and reduced nicotinamide adenine dinucleotide-diaphorase stains for degree of acute destruction, depth of thermal injury, and predicted viability.

RESULTS

All 80 degrees C sheep treatments resulted in complete loss of viability at mucosal, submucosal, and myometrial levels. In human uteri temperatures > or = 80 degrees C produced grossly recognizable thermal damage to the endometrium. Full-thickness irreversible damage was seen in the endometrium. Loss of viability was also demonstrated 1 to 3 mm deep in the superficial myometrium. Intrauterine pressure was demonstrated to range from 20 to 40 mm Hg, with a mean of 26 mm Hg. No leakage of fluid from the oviducts was observed.

CONCLUSION

The data presented here demonstrate that a simple technique coupled with a sophisticated monitoring control system could successfully ablate the endometrium without the vagaries associated with individual operator skill levels.

Microvascular transplantation of cryopreserved knee joints

Successful transplantation of cryopreserved complex tissues has not yet been reported. We wanted to test whether microvascular transplantation of cryopreserved knee joints can be achieved in rats. Twenty-five knee joints were cryopreserved and then microsurgically transplanted to the groin of inbred recipient animals. Ten fresh knee joints were transplanted as controls. One week after transplantation, the transplants were evaluated in situ for pedicle patency and tissue perfusion and then harvested for histology. In all surviving rats (n = 21), the cryopreserved knee joints were well perfused immediately after transplantation. At harvest, 14 knee joints appeared viable with a patent pedicle, whereas 6 were questionably viable and demonstrated arterial thrombosis. Histologically, the viable joints revealed an intact bone and cartilage matrix; however, the number of viable chondrocytes and osteocytes was reduced. Additionally, endothelial cell plugs in some areas of the capillary bed led to scattered microinfarctions despite a patent vascular pedicle. The nonperfused transplants showed infarction. In conclusion, we have demonstrated successful microvascular transplantation of cryopreserved knee joints with reduced short-term viability. Long-term studies must determine whether full recovery occurs.

In situ analysis of cellular proliferation in canine, feline and equine tumors by immunohistochemistry: a comparison of bromodeoxyuridine, proliferating cell nuclear antigen, and interchromatin-associated antigen immunostaining techniques

Cell proliferation in canine, feline, and equine tumors was evaluated using immunohistochemical detection of in vitro 5-bromodeoxyuridine (BrdU) incorporation, proliferating cell nuclear antigen (PCNA), and interchromatin-associated antigen (p105). Ten tumors in each species were analyzed. The tumor proliferative fraction (PF) was defined as the percentage of labeled nuclei for 5,000 tumor nuclei counted. Immunoreactivity was observed with all techniques in all species. A good correlation was observed between the proliferative fractions measured with the BrdU (PFBrdU) and PCNA (PFPCNA) techniques (rs = 0.523, P = 0.0026). There was no correlation between the PFs measured with the BrdU (PFBrdU) and p105 (PFP105) techniques. Using the median values obtained from the different approaches as cutoff points to define slowly and rapidly proliferating tumors, there was an 80% agreement (P = 0.009) between PFBrdU and PFPCNA and no agreement between PFBrdU and PFP105. The results of this study indicate that both BrdU and PCNA labeling methods can be used reliably for identifying proliferating cells in animal tumors. In addition, PCNA could be used to replace the BrdU method to assess tumor proliferative fraction because it does not require pretreatment of tissues.

Noninvasive evaluation of the aorto-iliac segment

Eighty-five patients (169 limbs) were studied in the Noninvasive Vascular Laboratory at the Lahey Clinic as part of a preoperative evaluation for arterial insufficiency. Segmental Doppler systolic pressures and peak velocity waveform analysis using a directional Doppler were performed on all patients. Normal velocity waveforms demonstrated forward flow during systole, reverse flow during the first half of diastole and a return to forward flow again during the latter part of diastole (triphasic flow). Significantly abnormal waveforms did not demonstrate reverse flow during the first half of diastole (monophasic flow). A significantly abnormal angiogram showed a greater than 50% stenosis in the aorto-iliac segment. A comparison of Doppler velocity waveforms with arteriograms showed a 96% correlation. Most errors in our study were technical; related to the assumption that the inguinal skin crease marked the location of the inguinal ligament and the origin of the common femoral artery. In these instances, the superficial femoral artery not the common femoral artery was sampled. Common sources of false positive studies were severe outflow obstruction or recent surgery to the common femoral artery, both showing a loss of laminar flow and a monophasic waveform. Patients who demonstrate reverse flow in the common femoral artery by directional Doppler examination had adequate inflow to support a femoral-popliteal or femoral-femoral by pass graft. Patients with monophasic flow had either inadequate aorto-iliac segments, recent surgery to the common femoral artery or severe outflow obstruction. Supportive data will be presented in detail.