Search

An impeded blood flow through the femoral head is incriminated in the etiopathogenesis of osteonecrosis of the femoral head. The disorder is either primary (idiopathic avascular osteonecrosis) or secondary to one condition or another, such as corticosteroid medication, fracture of the neck, coagulation defects, physical or thermal damage, storage disorders, alcoholism, and infectious, autoimmune as also marrow infiltrating diseases. In the wake of the necrosis, several mediators are released in increased amounts, prime among which is the vascular endothelial growth factor. The intermediates recruit endothelial progenitor cells, macrophages, osteoclasts, fibroblasts, and osteoblasts, which, pervading throughout the necrotic areas, initiate the reparative processes. The dead, soft, and hard tissular debris is substituted by fibrous — later on by hematopoietic-fatty tissue — and bone. The newly formed, appositional and intramembranous bone is deficient in its mechanical properties. The ordinary load-carrying functions suffice to deform these weakened femoral heads so that osteoarthritic changes develop. Considering contemporary assumptions of the causes of osteonecrosis, oxygenation, revascularization, and core decompression are the realistic therapeutic interventions. Necrosis of rats’ femoral heads is studied as a model of osteonecrosis in both adults and children. In view of rodents’ lifelong persisting physeal cartilage, vascular deprivation-induced osteonecrosis in rats mimics children’s Perthes disease. The experimental model, which is well suited to test treatment modalities, has been used to investigate the effects of exposure to hyperbaric oxygen with and without non-weight bearing, medication of enoxaparin, and creation of an intraosseous conduit on the remodeling of the avascular necrotic femoral head. Intriguingly, the shape of treated rats’ femoral heads is disfigured to a greater degree than that of untreated animals. This is most likely due to the reduced yield strength and elastic modulus as well as the raised strain-to-failure of the recently formed bone making up the post-necrotic femoral heads. It follows that expedited osteogenesis is, counter intuition, detrimental to maintaining the hemispherical shape of the femoral head, and thus to an articulation with congruent load-bearing surfaces. If this is indeed the case, the remodeling of the necrotic femoral head should be delayed, rather than sped up, as the present day paradigm would have it. Bearing in mind that the dead osseous structures keep their mechanical attributes for quite a while, a slowed down new bone formation would favor the gradual replacement of the necrotic by living bone. Therefore, management of the adult patients with osteonecrosis and children with Perthes disease should focus on a slowly progressive substitution so that the decline of the bone’s mechanical properties is kept to a minimum. One viable therapeutic mode is a medication of inhibitors of the vascular endothelial growth factor. [ABSTRACT FROM AUTHOR]

The right parolid duct of rats was instilled five to eight times with bovine serum albumin at daily intervals. Acute parotitis developed in non-sensitized animals, while chronic destructive sialoadenitis ensued in preimmunized rats. The morphological changes were reminiscent of those found in the salivary glands of patients with Sjögren's syndrome. [ABSTRACT FROM AUTHOR]

Rats were immunized by one to eight intraperitoneal administrations of species-homologous kidney fractions (prepared according to Ryan's differential centrifugation technique) emulsified in Freund's complete adjuvant. Proliferative and membranous glomerulitis ensued in about one-third of animals receiving five or more injections of any of the four renal preparations, i.e. heavy particle, mitochondrial, microsomal and soluble fractions. A significant increase in the in- cidence and titre of complement-fixing antibodies to renal antigens occurred, beginning with the third injection in rats sensitized with the heavy particle material and soluble fraction, and possibly also with the microsomal fraction; the mitochondrial fraction was ineffective in this respect. In this as in previous studies, neither a positive nor a negative correlation was established between the development of renal disease and the formation of circulating antibodies, glomerulitis frequently being found in the absence of detectable antibodies and vice versa. It is hypothesized that immunization with renal antigens elicits an immune response in the wake of which two independent processes are observed, namely the development of renal disease and the formation of circulating antibodies. [ABSTRACT FROM AUTHOR]

Total excision of colonic polyps is not always attainable and in some patients it is clinically contraindicated. Also, a resected polyp may be lost at any step between its endoscopic removal and its embedding in paraffin. The aim of this study was to compare the histological features of colonic polyps as analysed by the study of biopsy-forceps obtained samples with those assessed on scrutinizing the totally resected growths.This prospective study included a cohort of 59 patients in whom, in the course of an elective colonoscopy, a total excision of a 6 mm-sized or larger polyp was called for. Sizeable biopsies were obtained by means of an Olympus Multibyte forceps prior to the total polypectomy. Subsequent to the study of the polypectomy specimens, the forceps biopsy samples were submitted for histological examination. The pathologists were blinded as to the source of the tissue they were studying. The diagnoses rendered by evaluating the biopsy samples and polypectomy specimens of each patient were contrasted with each other.Major discrepancies between the histological features of the fragments captured by the biopsy-forceps and the factual nature of the totally removed polyps were uncovered in 11 (18.6%) of 59 cases. Intriguingly, the grade of the tumours was underrated in all the 11 cases, as judged by contrasting the tentative diagnoses of the forceps-biopsies with the decisive diagnoses of the polypectomies. Importantly, 2 adenocarcinomas would have been missed by just looking at the forceps-retrieved sample.In our experience, a discordance of 18.6% is to be expected between the diagnoses rendered after examining forceps-biopsies of and totally excised colonic polyps. Nevertheless, it is advisable to procure biopsies prior to the excision of the growths, because on those occasions in which patients' growths cannot be removed or have not been retrieved for one reason or another, a small forceps-captured tissue sample correctly reflects the characteristics of the polyp in 81.4% of the cases. Finally, the biopsies may be discarded in the event that total removal was successful. [ABSTRACT FROM AUTHOR]

Rats were passively immunized by an intraperitoneal injection of homologous anti-BSA serum and their salivary glands were challenged 20 min or 24 hours later with BSA by the intraductal route. Immune complex sialoadenitis developed only when challenge was early. It is concluded that immunoglobulins are transferred from the circulation into the salivary glands and are relatively rapidly cleared by a mechanism yet unknown, possibly by salivary flow. [ABSTRACT FROM AUTHOR]

Acute sialoadenitis, ascribed to local formation of immune complexes, develops in sensitized rats after a single intraductal challenge with the sensitizing antigen. Multiple intraductal challenges induce a state of non-reactivity of the organ characterized by a lack of inflammatory reaction to the sensitizing antigen. This non-reactivity is antigen-specific, since introduction of ovalbumin, after multiple intraductal instillations of bovine serum albumin (BSA), elicits an inflammatory response in animals immunized with the two antigens. At the same time, instillation of BSA into the contralateral gland, which has not been challenged, causes acute adenitis. Anti-BSA antibodies are detected in the serum and parotid saliva at the time of refractoriness of the gland. The phenomenon is a transient one since the faculty of the salivary gland to respond by an inflammatory reaction recovers after a challenge-free period. These experiments bring to light a new phenomenon, the possible mechanisms of which are discussed. [ABSTRACT FROM AUTHOR]

The parotid gland and knee joint of immunized ruts were challenged with the sensitizing antigen. Sialoadenitis developed in over half of these rats alter one and three challenges via the parotid duct. On the other hand, most glands were normal after five, seven and eight intraductal challenges in spite of the presence of precipitating antibodies in the serum and hemagglutinating antibodies in the parotid saliva; in only a few animals did chronic destructive adenitis ensue. This contrasted with the incidence and severity of synovitis, which increased with the number of intra-articular injections of antigen, The non-reactivity of the gland is antigen specific in as much as acute adenitis resulted from intraductal instillation of a second antigen following multiple challenges with another one in rats sensitized with two antigens. The results evince a difference in the local reactivity between the salivary gland and synovial membrane. [ABSTRACT FROM AUTHOR]