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Biomedical subjects

D M Knowles

Publications and source records attributed to D M Knowles.

222 records · Page 13Linked to original sources
PubMed1975

Rhabdomyoma of the orbit.

To our knowledge, this is the first fully documented case of an adult-type orbital rhabdomyoma in an 8-year-old white boy, which originated in the belly of the medial rectus muscle and grew into the anterior orbit to incorporate the trochlea. Incomplete excision resulted in recurrence; the lesion was misinterpreted as a rhabdomyosarcoma and exenteration was performed. The patient was free of disease 25 years later. Reexamination of original pathologic material showed the typical histology of an adult-type rhabdomyoma. Adult-type rhabdomyoma, the most differentiated tumor in a spectrum of benign and malignant striated muscle neoplasms, should be distinguished from fetal rhabdomyoma (also benign) and pleomorphic rhabdomyosarcoma, the malignant striated muscle tumor most likely to be confused with rhabdomyoma. An awareness of the benign nature of rhabdomyoma (rhabdomyoma never evolves into a sarcoma) should prevent unnecessary radical surgery. The tumor can be adequately managed by a local excision that includes all the lobulations of tumor within a margin of normal tissue.

Child↗
PubMed1975

Nodular regenerative hyperplasia of the liver.

Nodular regenerative hyperplasia of the liver, an uncommonly reported and poorly defined clinicopathological entity, obscured clinical diagnosis and was misdiagnosed on hepatic biopsy in a recent case. Approximately 19 cases are recorded in the English literature. Six patients had Felty's syndrome, about 12 patients had congestive heart failure, and the patient under discussion had subacute bacterial endocarditis. Light- and electron-microscopic examination was utilized to define nodular regenerative hyperplasia pathologically. Features common to all reported cases are discussed but elucidation of the pathogenesis of nodular regenerative hyperplasia must await further investigation.

Adult↗
PubMed1973

In vitro antibody-enzyme conjugates with specific bactericidal activity.

IgG with antibacterial antibody opsonic activity was isolated from rabbit antisera produced by intravenous hyperimmunization with several test strains of pneumococci, Group A beta-hemolytic streptococci, Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa, and Escherichia coli. Antibody-enzyme conjugates were prepared, using diethylmalonimidate to couple glucose oxidase to IgG antibacterial antibody preparations. Opsonic human IgG obtained from serum of patients with subacute bacterial endocarditis was also conjugated to glucose oxidase. Antibody-enzyme conjugates retained combining specificity for test bacteria as demonstrated by indirect immunofluorescence. In vitro test for bactericidal activity of antibody-enzyme conjugates utilized potassium iodide, lactoperoxidase, and glucose as cofactors. Under these conditions glucose oxidase conjugated to antibody generates hydrogen peroxide, and lactoperoxidase enzyme catalyzes the reduction of hydrogen peroxide with simultaneous oxidation of I(-) and halogenation and killing of test bacteria. Potent in vitro bactericidal activity of this system was repeatedly demonstrated for antibody-enzyme conjugates against pneumococci, streptococci, S. aureus, P. mirabilis, and E. coli. However, no bactericidal effect was demonstrable with antibody-enzyme conjugates and two test strains of P. aeruginosa. Bactericidal activity of antibody-enzyme conjugates appeared to parallel original opsonic potency of unconjugated IgG preparations. Antibody-enzyme conjugates at concentrations as low as 0.01 mg/ml were capable of intense bactericidal activity producing substantial drops in surviving bacterial counts within 30-60 min after initiation of assay. These in vitro bactericidal systems indicate that the concept of antibacterial antibody-enzyme conjugates may possibly be adaptable as a mechanism for treatment of patients with leukocyte dysfunction or fulminant bacteremia.

Agglutination Tests↗
PubMedDate not supplied

Ophthalmic striated muscle neoplasms.

Rhabdomyosarcoma, the most common primary malignant childhood orbital tumor, is composed of neoplastic striated muscle cells (rhabdomyoblasts) in various stages of differentiation and in patterns suggestive of neoplastic analogs of normal muscle embryogenesis. Orbital rhabdomyosarcoma is most commonly seen in children and adolescents, the average age of onset of symptoms being 7.8 years. The tumor usually presents as a rapidly evolving exophthalmos, often associated with drooping of the upper eyelid. A mass is palapable in only 25% of cases, loss of central vision at the time of presentation is uncommon, and laboratory studies are often of little help in diagnosis. The best diagnostic aid is a high index of suspicion whenever one sees a rapidly progressive exophthalamos in a child. Orbital rhabdomyosarcoma is almost always of the embryonal type, believed to originate in the orbital soft tissues from undifferentiated pluripotential embryonic mesenchyme. In the past, orbital exenteration has been the primary therapy. Review of 162 literature cases of orbital rhabdomyosarcoma, generally treated by unassisted surgery, revealed that only 25% of the patients survived 3 or more years. Recently, it has been shown that radiation therapy, alone or combined with chemotherapy, can be successful. A multidisciplinary approach, utilizing surgery, radiation therapy and chemotherapy has also been advocated. Both approaches appear to offer greater survival than unassisted orbital exenteration. The possibility of primary radiation therapy is extremely promising; if it becomes increasingly effective, a mutilating surgical procedure may become obsolete.

Adolescent↗
PubMedDate not supplied

Amyloidosis of the orbit and adnexae.

Five patients representing a spectrum of orbital and adnexal amyloidosis are presented. One patient with conjunctival amyloidosis did not have antecedent infection nor systemic disease (primary localized amyloidosis), while another patient with conjunctival amyloidosis had a long history of repeated attacks of bacterial conjunctivitis (secondary localized amyloidosis). The third patient presented with serial bilateral lacrimal gland amyloid without systemic disease (primary localized orbital amyloidosis). Another patient had intraorbital amyloid associated with metastatic deposits or immunoglobulin-producing lymphoma cells in the orbit (secondary systemic amyloidosis) and a fifth patient, with borderline Congo red staining for amyloid, was shown by electron microscopy to have macrophages with intracellular amyloid-like fibrils and extracellular crystalline material resembling immunoglobulin deposits. Amyloidosis has been clearly shown to be associated with immunoglobulins and plasma cells. Electron microscopic findings in our two cases of primary localized orbital amyloidosis leave unresolved the suggestion that mesenchymal cells, in addition to plasma cells, may be responsible for the production of amyloid. It should be emphasized for the clinician that amyloidosis of the conjunctiva and orbit is almost always a benign disease without systemic implications. On the other hand, amyloid of the skin of the eyelids, is a hallmark of generalized amyloidosis.

Adult↗