Evelyn A. Kazacos

The raccoon ascarid. A probable cause of human ocular larva migrans.

The ability of raccoon roundworm larvae, Baylisascaris procyonis, to produce ocular larva migrans (OLM) was studied in various experimental animals. In addition, the clinical and pathologic lesions were compared to those in suspected cases of human ocular baylisascariasis, in patients with diffuse unilateral subacute neuroretinitis (DUSN). Ocular larva migrans was produced in squirrel monkeys, cynomolgus monkeys, mice, hamsters, grey squirrels, and woodchucks orally infected with B. procyonis eggs. The clinical and histologic lesions were primarily those of retinitis, retinal hemorrhages, retinal tracks, disruption, and vasculitis; pigment migration; choroiditis; vitritis; and free or encysted larvae in ocular and extraocular tissues. The lesions of experimental OLM correlated well with those of suspected cases of human ocular baylisascariasis and DUSN. Based on these studies, B. procyonis of raccoons should be considered as a probable cause of OLM and DUSN in humans.

Morphologic study of three collagen materials for body wall repair

BACKGROUND The search for ideal prostheses for body wall repair continues. Synthetic materials such as polypropylene mesh (PPM) are associated with healing complications. A porcine-derived collagen-based material (CBM), small intestinal submucosa (SIS), has been studied for body wall repair. Renal capsule matrix (RCM) and urinary bladder submucosa (UBS) are CBMs not previously evaluated in this application. This is the first implant study using RCM. MATERIALS AND METHODS Full-thickness muscle/fascia ventral abdominal wall defects were repaired with SIS, RCM, UBS, and PPM in rats with omentum and omentectomy. A random complete block design was used to allot implant type to each of 96 rats. Healing was evaluated at 4 and 8 weeks. Adhesion tenacity and surface area were scored. Implant site dimensions were measured at implantation and necropsy. Inflammation, vascularization, and fibrosis were histopathologically scored. Data were compared by analysis of variance (P < 0.05). RESULTS PPM produced a granulomatous foreign body response in contrast to the organized healing of CBM implants. CBM mean scores were lower than PPM scores for adhesion tenacity, surface area, and inflammation at each follow-up time for rats with omentums (P < 0.02). The CBMs had less tenacity and inflammation than PPM at each follow-up time in omentectomy groups (P < 0.008). Wound contraction was greater for PPM (P < 0.0001) for all rats. CONCLUSIONS RCM and UBS were similar to SIS invoking reduced inflammation, adhesion, and contraction compared to PPM. The fibrotic response to PPM was unique and more intense compared to CBMs. These CBM implants appear morphologically acceptable and warrant continued investigation.

Pathologic Features of Naturally Occurring Juvenile Polyarteritis in Beagle Dogs

Eighteen young Beagle dogs (eight males and 10 females), ages 6-40 months, with canine juvenile polyarteritis syndrome (CJPS), a naturally occurring vasculitis and perivasculitis of unknown etiology, were necropsied, and their tissues were examined by histopathologic and histochemical methods. The condition is characterized by recurring episodes of an acute onset of fever (>40 C) and neck pain that persist for 3-7 days. The major histopathologic alterations were a systemic vasculitis and perivasculitis. During the febrile, painful period of CJPS, the vascular lesions ranged from a histiocytic-lymphocytic periarterial infiltration to transmural arterial inflammation with concomitant fibrinoid necrosis and vascular thrombosis. Massive periarterial accumulations of inflammatory cells were common and often extended into adjacent tissues. The small- to medium- sized muscular arteries of the heart, cranial mediastinum, and cervical spinal meninges were consistently involved. Vasculitis occasionally occurred in other organ systems. The vascular lesions in dogs examined during clinically normal periods consisted of intimai and medial fibrosis, ruptured elastic laminae, and mild perivasculitis; these lesions were probably related to previous episodes of vasculitis. Eight dogs that had experienced repeated acute episodes also developed splenic, hepatic, and renal amyloidosis. The clinical signs, laboratory abnormalities, and the vascular lesions suggest that the condition may be immune-system mediated. CJPS may serve as a naturally occurring animal model of human immune-system-mediated vasculitides such as polyarteritis nodosa, infantile polyarteritis, and Kawasaki disease.

Pathology of pentastomid infections (Sebekia mississippiensis) in fish.

Differential pathogenesis was observed in two species of fish naturally infected with the pentastome Sebekia mississippiensis. Mosquitofish (Gambusia affinis) showed a mild inflammatory response to developing nymphs, whereas swordtails (Xiphophorus helleri) had an extensive granulomatous inflammatory reaction with accompanying hemorrhage, myositis, and myodegeneration. This suggested that certain species of tropical fish reared in the southeastern United States may be at risk to potentially harmful infections with this parasite.

Histopathology of nymphal pentastomid infections (Sebekia mississippiensis) in paratenic hosts.

The histopathologic alterations occurring in mice, hamsters, turtles, and a frog were described following experimental infection with nymphs of Sebekia mississippiensis. Initially, nymphal migration caused traumatic tissue damage and hemorrhage characteristic of larva migrans. Subsequent inflammatory responses included cellular infiltration with eosinophils, macrophages, and lymphocytes, and fibrotic encapsulation of the nymphs. Dead nymphs were surrounded by a necrotic granulomatous response similar to that reported previously in humans and other animals. Differences were not seen in animals given single or multiple infections, but mice and hamsters exhibited a more marked inflammatory response than turtles. Overall, the histopathologic response to nymphal infections resembled those seen in infections resulting from ingestion of eggs, and both sources of infection should be considered in epidemiologic investigations of naturally occurring pentastomiasis.

Chronic Hernia Repair in a Rat Model Using Small Intestinal Submucosa

ABSTRACT Background. Small intestinal submucosa (SIS) body wall defect repair in preclinical studies results in host tissue that resembles original host tissue histologically and has adequate strength to maintain repair integrity. However, these studies have been performed using acute hernia models that may not represent healing in a naturally occurring hernia. Methods. Fifty-four male Sprague–Dawley rats were divided into nine groups (n = 6) and fascia/muscle/peritoneal abdominal wall defects were created. One control group had no surgery. Four surgery groups had defects repaired immediately by (1) fascia suture apposition, (2) polypropylene mesh (PPM) peritoneal onlay, (3) SIS inlay, or (4) SIS peritoneal onlay. After defect creation, chronic hernias matured for 28 days, and then were similarly repaired. Follow-up after hernia repair for all groups was 28 days. Gross evaluation for hernia recurrence, infection, and adhesions was followed by histopathology and tensile testing of the repair. Results. There were no recurrent hernias or infection. Adhesions covered all implants. Histopathologic findings of inflammation and fibrosis were similar between all groups. There were no significant differences in tensile strength between SIS and PPM healing/incorporation or between acute and chronic hernia groups. Normal body wall was stronger than all repairs. Fascia closure in chronic hernias was stronger than acute fascia closure (p < .01). Conclusions. We found no significant differences between SIS and PPM healing/incorporation as determined by gross and histopathology and tensile strength testing. The study suggests that preclinical testing of abdominal body wall reconstruction in the rat may be adequately performed in acute studies.

OCULAR, NASO-MAXILLARY, AND NEURAL ANOMALIES IN RACCOONS, PROCYON LOTOR (L.)1

Congenital ocular and related anomalies were studied in two unrelated young raccoons. One animal was anophthalmic and had severe anomalies of the central nervous system, consisting of meningoen-cephalocele, pachygyria, hydraneneephaly, cerebellar cavitation, syringomyelia, and other defects. A second animal was microphthalmic with congenital defects of the nose, maxilla and teeth. Ocular lesions were severe and included chorioretinal colohoma, retinal folds, disorganized neuroectodermal cell layers, spherophakia, cataract and other defects. The nose had unilateral abnormal epithelium, hair follicles, sweat glands and sebaceous glands, and a lack of parietal cartilage on the affected side.

Teratogenicity of 3,3-dimethyl-1-phenyltriazene: distribution in rats and rat embryos

3,3-Dimethyl-1-phenyltriazene (DMPT) is a methylating agent which is carcinogenic, teratogenic and mutagenic which, in the rat, provides a reproducible animal model with which to study the basis of chemically-induced micrognathism. The basis of teratogenic organotropism of DMPT and other methylating teratogens is unknown. The present study was undertaken to determine if limited chemical distribution within the embryo was responsible for the organotropism of DMPT. Whole-embryo autoradiographs and liquid scintillation analysis indicated that although DMPT may have some limitations of chemical distribution within the embryo, these limitations are not sufficient to explain its teratogenic organotropism.