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Biomedical subjects

G L Bratthauer

Publications and source records attributed to G L Bratthauer.

45 records · Page 3Linked to original sources
PubMed1991

Retroviral vector-mediated in vivo expression of low-density-lipoprotein receptors in the Watanabe heritable hyperlipidemic rabbit.

We have achieved in vivo expression of recombinant low-density-lipoprotein (LDL) receptors in the Watanabe heritable hyperlipidemic (WHHL) rabbit, an animal model for the human disease familial hypercholesterolemia. A retroviral vector was constructed containing the human LDL receptor cDNA and was used to stably transduce primary skin fibroblasts from WHHL rabbits. The integrity and function of the introduced LDL receptor was established by immunoprecipitation, by a fluorescent LDL binding assay, and by the ability of the transduced cells to suppress 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase activity in response to exogenous cholesterol. Autologous transduced fibroblasts were reimplanted into donor rabbits; in vivo LDL receptor expression and the survival of the transduced cells were analyzed by immunohistochemistry and by LDL binding assays performed on cells recovered from the implants. LDL receptor-bearing cells could be identified on tissue sections and recovered from implants for up to four weeks. Total and LDL cholesterol levels decreased significantly after implantation of the transduced cells; however, control experiments indicated that the decreases were not mediated through the recombinant LDL receptor. While in vivo stable expression of recombinant LDL receptors in Watanabe rabbits is possible, consequent changes in lipid levels must be interpreted with caution. This system of site-specific in vivo expression of recombinant LDL receptors permits further evaluation of the role of LDL receptor-gene replacement in the therapy of hypercholesterolemia.

Animals↗
PubMed1991

Epithelioid variant of malignant peripheral nerve sheath tumor (malignant epithelioid schwannoma).

Twenty-six cases of malignant peripheral nerve sheath tumor with a predominant epithelioid pattern were studied to determine the range of its histologic patterns, immunophenotype, and biologic behavior. The tumor presented as an asymptomatic mass either in superficial (16 cases) or in deep soft tissue (10 cases) of the extremity. Characteristically, those in deep soft tissue were composed of vague nodules of varying cellularity made up of cords or strands of rounded epithelioid cells with prominent nucleoli. Those in superficial soft tissue were uninodular masses composed of tight clusters of cells showing cell-to-cell molding but possessing the same prominence of nuclei and mitotic activity as those in deep soft tissue. Several were associated with a preexisting benign nerve sheath tumor. A number of cases deviated from the above description, including cases that resembled a clear cell carcinoma, a malignant rhabdoid tumor, and a pleomorphic sarcoma. The majority of cases (80%) strongly expressed S-100 protein and neuron-specific enolase, but all lacked a melanoma-associated antigen (as defined by HMB-45) and cytokeratin. Stains for type IV collagen defined linear immunoreactivity around single cells and groups of cells. This pattern did not differ substantially from that of melanomas and therefore did not serve as a reliable discriminant. Follow-up information indicated a more favorable course for those in superficial soft tissue compared with those in deep sites. Two of 16 patients in the former group developed metastatic disease compared with three of 10 in the latter group. Tumors in superficial soft tissue may be eminently treatable and curable, depending on size.

Adolescent↗
PubMed1991

Migration and death of skin-dwelling Onchocerca volvulus microfilariae after treatment with ivermectin.

The effects of a single dose of ivermectin (122-200 micrograms/kg) on Onchocerca volvulus microfilariae (mf) in skin and lymph nodes were studied histologically in a qualitative and quantitative manner over seven days after treatment. Ivermectin caused mf to move from the subepidermal layer into the deeper layers of the dermis, subcutaneous fat and connective tissue, and the regional lymph nodes. No mf were seen migrating upwards through the epidermis. Dead mf were not seen before 24 hr and the numbers found dead in the dermis were far fewer than the total numbers in the skin before treatment. Inflammatory cellular reaction around dead mf in the tissues was usually minimal. The results suggest that most of the mf which disappear from the skin may be destroyed in the lymph nodes and that the histological reaction excited by mf dying under ivermectin is less violent than that after diethylcarbamazine.

Adult↗
PubMed1990

Immunohistochemical staining with monoclonal Ab B72.3 in benign and malignant breast disease.

A variety of benign and malignant breast lesions were evaluated for their reactivity with the monoclonal antibody B72.3. The lesions included invasive duct carcinoma (15 cases), apocrine carcinoma (18 cases, nine invasive and nine in situ lesions), well-differentiated (tubular) carcinoma (15 cases), invasive lobular carcinoma (10 cases) and lobular neoplasia (10 cases), intraductal hyperplasia (nine cases), atypical intraductal hyperplasia (eight cases), intraductal carcinoma (15 cases), sclerosing adenosis (15 cases), and apocrine metaplasia (24 cases). Only 20% of the invasive ductal carcinomas and 27% of the intraductal carcinomas showed a positive reaction for B72.3. Ten percent of the lobular neoplasias and 25% of the invasive lobular carcinoma reacted with B72.3. None of the 15 tubular carcinomas or the 15 cases of sclerosing adenosis reacted. One of eight examples of atypical intraductal hyperplasia (12.5%) showed a positive reaction, but none of the nine intraductal hyperplasias reacted with B72.3. The most consistently positive results were observed in cases displaying apocrine metaplasia. A positive reaction was observed in 23 of the 24 cases of apocrine metaplasia (96%) and 17 of 18 cases of apocrine carcinoma (94%). Thus we conclude that B72.3 is neither specific nor sensitive for the detection of malignant breast lesions. However, it does appear to be a valuable marker for the presence of apocrine differentiation, which is not a known precursor of carcinoma.

Antibodies, Monoclonal↗
PubMed1990

A genetic therapy for familial hypercholesterolemia.

The WHHL rabbit serves as an animal model for the human genetic disease, familial hypercholesterolemia. In initial studies aimed at the development of a genetic therapy for familial hypercholesterolemia (i.e., introduction of a normal LDL receptor gene), WHHL rabbit skin fibroblasts were transduced with a retroviral vector expressing a normal human LDL receptor. Correction of the WHHL rabbit genetic defect in vitro was confirmed. Autologous fibroblasts expressing LDL receptors were reimplanted in donor rabbits and were found to survive and express the recombinant receptor in vivo for up to 4 weeks. In vivo LDL receptor expression by autologous cells stably transduced with functioning LDL receptors is possible. Transduction of greater numbers of cells along with increased cell survival in vivo may eventually lead to a specific and effective genetic therapy for familial hypercholesterolemia.

Animals↗
PubMed1989

Palisaded myofibroblastoma. A benign mesenchymal tumor of lymph node.

We report 22 examples of an unusual and distinctive benign mesenchymal tumor arising exclusively from lymph nodes of the groin. The tumor, which presents clinically as a swelling, is composed of spindled cells arranged in solid sheets or short, vaguely palisaded fascicles similar to a neurilemoma. The spindled cells blend gradually with large mats of eosinophilic material that appear as thick bands, ellipses, or circular profiles, depending on the plane of section. These eosinophilic structures, which represent a highly characteristic feature of the tumor, contain deeply eosinophilic, collagen-rich cores surrounded by a weakly eosinophilic, actin-rich cuff. The actin within these eosinophilic structures is derived by coalescence of intracellular actin globules extruded from neighboring cells. In all cases, a thin, compressed rim of normal lymph node was identified. Immunohistochemical analysis indicates that the cells express actin but lack S-100 protein, synaptophysin, desmin, keratin, and epithelial membrane antigen. Delicate, linear striations were identified in only two cases by conventional histochemical techniques. The foregoing features suggest that the tumor is related to a myofibroblast or a specialized smooth-muscle cell. These tumors, therefore, probably arise from smooth-muscle-like cells, which are normally present in some lymph node capsules or stroma. Follow-up information on 17 patients indicated that all are alive and well without any evidence of recurrence or metastasis.

Adult↗
PubMed1988

Immunohistochemical localization of hepatitis B surface antigen and hepatitis B core antigen in tissue sections. A source of false positive staining.

The occurrence of apparent false positive immunoperoxidase staining for hepatitis B surface antigen (HBsAg) led to the evaluation of several commercial antisera for usefulness in the diagnosis of hepatitis B by immunohistochemistry. One commercial antibody to hepatitis B core antigen (HBcAg) was tested and found to give sensitive and specific staining, with only a few false negatives and no false positives. Of three antibodies to HBsAg, one gave good staining results that were consistent with serologic data; one had many false positive stains due to contaminating antibodies to plasma proteins; and one (a monoclonal antibody) had many false negatives, probably due to its restricted antigenic specificity. Diagnosticians should be aware of the problems with false positive and false negative immunohistochemical stains. False positives in particular can be a significant problem, causing frequent misdiagnosis of hepatitis B.

False Positive Reactions↗
PubMed1988

Postirradiation malignant fibrous histiocytoma expressing cytokeratin. Implications for the immunodiagnosis of sarcomas.

A malignant fibrous histiocytoma of the sacrum complicating the course of radiation therapy for endometrial carcinoma is presented. Although the tumor fulfilled the clinical, radiologic, and histologic criteria for a postirradiation malignant fibrous histiocytoma of bone, it also expressed cytokeratin. That this immunoreactivity reflected keratin synthesis by the tumor and not an unusual pattern of cross-reactivity with another intermediate filament such as vimentin is strongly suggested by the reproducibility of the immunoreactivity utilizing both polyclonal and monoclonal antibodies and extinction of the immunoreactivity following absorption of the primary antiserum with keratin proteins. This is the first reported instance of keratin expression by a malignant fibrous histiocytoma; it indicates that sarcomas apart from synovial sarcoma and epithelioid sarcoma may sometimes express this protein.

Aged↗