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Biomedical subjects

A N Walker

Publications and source records attributed to A N Walker.

At least 19 recordsLinked to original sources
PubMed1992

Murine Pneumocystis carinii adherence to vertical monolayers of cultured mink lung cells (MiCl1).

We describe a method for adherence and culture of murine Pneumocystis carinii in mink lung cells (MiCl1) grown on vertical supports. The vertical cultures were infected with P. carinii; the surrounding medium and inoculum were stirred to ensure circulation and contact with MiCl1 cells. When compared with conventional horizontal culture, the vertical method offers a more suitable system for assessing P. carinii adherence. This approach has proved suitable for quantitative evaluation of P. carinii adherence to MiCl1 cells in the presence of inhibitors.

Animals↗
PubMed1991

Small-cell neuroendocrine carcinoma of the cervix. A human papillomavirus type 18-associated cancer.

Small-cell undifferentiated carcinomas comprise a rare but aggressive subset of uterine cervical neoplasms. Analogous to small-cell anaplastic carcinoma of the lung, these tumors frequently exhibit neuroendocrine differentiation. Although human papillomaviruses (HPV) types 16 and 18 are strongly associated with the development of cervical squamous carcinoma, there is as yet little information describing the relationship of these viruses to small-cell carcinomas. To address this question, we analyzed 20 cases of small-cell carcinoma of the cervix using in situ hybridization to detect HPV gene expression. In addition, immunohistochemistry was used to evaluate three markers of neuroendocrine differentiation. Eighteen of 20 tumors (90%) demonstrated some evidence of neuroendocrine differentiation; 17 of 20 (85%) expressed HPV type 16 or 18 messenger RNA. Of the neuroendocrine-positive cases, 14 of 18 expressed HPV 18 messenger RNA. In contrast, both of the cases with squamous differentiation were HPV 16 positive. These findings broaden the spectrum of HPV-associated cervical neoplasia and strongly suggest that HPV 18 is a viral type specifically associated with cervical small-cell neuroendocrine carcinomas.

Carcinoma, Small Cell↗
PubMed1991

Immunocytochemical labeling of chitin in the cell walls of zoopathogenic fungi.

Chitin is a complex polysaccharide composed of repeating units of beta-1,4-N-acetyl-D-glucosamine. It is found in many invertebrates, in some algae, in the cyst form of several protozoans and in the cell walls of most fungi. Chitin, however, is not expressed in vertebrate tissues. We used a polyclonal rabbit antiserum against macromolecular chitin to label and stain by immunoperoxidase technique in formalin-fixed, paraffin-embedded tissues a variety of zoopathogenic fungi. The antiserum bound to the cell walls of the microorganisms, but not to (mammalian) host tissue elements.

Cell Wall↗
PubMed1990

Immunocytochemical detection of chitin in Pneumocystis carinii.

Polyclonal antisera against chitin and chitin oligomers were used to stain Pneumocystis carinii by the immunoperoxidase technique in Formalin-fixed, paraffin-embedded sections of four human lung biopsies and in alcohol-fixed, paraffin-embedded cell blocks of two bronchioloalveolar lavage specimens from infected human patients. In all cases, the antisera bound P. carinii but did not bind the host tissue elements. Moreover, the antisera bound not only to the cyst forms of P. carinii but also to the intracystic bodies and to the trophic forms. Preadsorption of the anti-chitin antiserum with purified chitin abolished all staining of P. carinii. Our results indicate that P. carinii produces chitin at more than one stage of its life cycle in the infected human host.

Animals↗
PubMed1990

Thymomas and thymic carcinomas.

This review discusses epithelial proliferations of the thymus, excluding carcinoid tumor and small cell carcinoma. The clinical features of thymoma, possible etiologic mechanisms, and associated autoimmune and paraneoplastic conditions are summarized briefly. Histologic subtypes of thymoma, including lymphocyte predominant, mixed, and spindle cell tumors are described and illustrated. The concept of "medullary" and "cortical" differentiation in thymoma is reviewed. Immunohistochemical and electron microscopic features of this neoplasm are presented. Flow cytometric studies relating to its prognosis also are summarized. Distinctions between encapsulated thymoma, invasive thymoma, and metastatic or "malignant" thymoma are described in detail. Thymic carcinomas are reviewed, as distinguished from cytologically bland thymomas. Variants of thymic carcinoma include squamous cell, spindle cell, lymphoepithelioma-like, mucoepidermoid, adenosquamous, clear cell, basaloid, and adenoid cystic neoplasms.

Carcinoma↗
PubMed1989

Scar-associated malignant melanoma and squamous carcinoma in situ.

The development of cutaneous neoplasms is a known sequela of chronic scars, squamous carcinoma being most common. We have described an elderly patient with both squamous carcinoma in situ and malignant melanoma in different scars. The coexistence of the lesions suggests a common pathogenesis.

Aged↗
PubMed1988

Primary carcinoid tumor of the testis.

We have presented a case of primary testicular carcinoid in an otherwise asymptomatic 50-year-old white man treated by right orchiectomy; a postoperative abdominal CT scan was normal. Histologically and cytologically the tumor resembled carcinoids of midgut origin. Most primary testicular carcinoid tumors are not clinically functional, and thus the diagnosis is not suspected preoperatively.

Carcinoid Tumor↗
PubMed1988

Immunohistochemistry: a useful adjunct in the evaluation of malignant cutaneous spindle cell tumors.

We used immunohistochemistry to evaluate four cytologically malignant cutaneous neoplasms on the face or neck of elderly individuals. All four lesions were composed of a dermal proliferation of spindle and pleomorphic giant cells. Differential diagnosis included spindle cell carcinoma, atypical fibroxanthoma, malignant melanoma, leiomyosarcoma, and angiosarcoma. All four neoplasms were strongly immunoreactive for vimentin and negative for cytokeratin, S100 protein, desmin, and factor-VIII-related antigen. Focal immunoreactivity for lysozyme and/or a1-antichymotrypsin was seen in the giant cells of each lesion. These results supported the diagnosis of atypical fibroxanthoma in each instance. Immunohistochemical staining can provide useful information for distinguishing among malignant cutaneous spindle cell tumors.

Aged↗
PubMed1988

Cervical neuroendocrine carcinoma: a clinical and light microscopic study of 14 cases.

Fourteen primary cervical neoplasms with light microscopic features of neuroendocrine carcinoma were studied. Two were of intermediate cell type (IC), resembling the pulmonary atypical carcinoid; seven were small cell type (SC), analogous to pulmonary oat cell carcinoma; two were SC with foci of IC; three were SC with foci of squamous or adenocarcinoma. Four patients were Stage I, five were Stage II, two were Stage III, and three were Stage IV. One patient (Stage I) underwent hysterectomy and has completed radiation therapy. Two patients underwent radical hysterectomy and chemotherapy. One received radiation and chemotherapy; one received only chemotherapy; nine received radical radiation therapy. One patient (Stage I) is alive and well 10.5 years later; one (Stage II) died of other causes 24 months after diagnosis. One other is alive with the disease 12 months postdiagnosis. Eleven died secondary to tumor, four to 33 months (mean 14, median 12.5 months) after diagnosis. There was no significant difference in survival between IC and SC types, either mixed or pure. Cervical neuroendocrine carcinomas are biologically aggressive neoplasms, regardless of histologic type.

Adult↗
PubMed1987

Preservation of pathology specimens by silicone plastination. An innovative adjunct to pathology education.

The authors have used the process of plastination to preserve gross anatomic specimens for teaching purposes. A specimen is fixed in 10% buffered formalin and dehydrated in increasing grades of ethanol. Thereafter it is saturated with methylene chloride and then impregnated in vacuo at -20 degrees C with silicone rubber. Final steps involve drainage and exposure to a curing agent. The total time required is approximately 16 weeks. The finished plastinated specimen is dry to the touch, odorless, and nontoxic, yet it maintains its original shape and, in many cases, is reasonably close in color and consistency. It resists deterioration and can be stored at room temperature indefinitely. The authors have found plastinated specimens to be superior to those preserved in formalin for teaching anatomic pathology to undergraduate medical students.

Costs and Cost Analysis↗
PubMed1986

Acral mucinous syringometaplasia. A benign cutaneous lesion associated with verrucous hyperplasia.

We describe herein a case of acral mucinous syringometaplasia that presented clinically as a verruca plantaris. Microscopically, verrucous hyperplasia of the epidermis and central, dilated eccrine ducts lined by a mixture of squamous and goblet cells were present. Mucinous syringometaplasia is a benign entity that should be distinguished from other mucin-containing cutaneous lesions.

Adult↗
PubMed1985

Discrepant fibrinogen values during thrombolytic therapy. Comparison of aca and Data-Fi results using immunofixation. Electrophoresis as a reference.

The authors compared aca and Data-Fi fibrinogen values and used a combination of plasma protein electrophoresis and immunofixation with anti-fibrinogen anti-serum to observe changes in fibrinogen from four patients receiving streptokinase (STK) therapy. For three patients, aca and Data-Fi values pre-STK and greater than or equal to 24 hours post-STK correlated well (r = 0.96, slope = 0.92, y-intercept = 2.3; n = 13 pairs); aca and Data-Fi values during STK therapy correlated poorly (r = 0.67, slope = 0.36, y-intercept = 4.1; n = 20 pairs), with aca values up to sixfold higher than Data-Fi. Protein electrophoresis and immunofixation showed loss of the discrete fibrinogen band during STK therapy; instead there was a diffuse electrophoretic zone of anti-fibrinogen reactive material having a slightly different mobility than intact fibrinogen; aca fibrinogen values were inconsistent with fibrinogen band absence. The remaining patient showed no change in the fibrinogen band. Clinically he showed no response to STK therapy. In nonresistant patients, STK results in the degradation of fibrinogen into a mixture of products (FDP), all sharing antigenic determinants with fibrinogen and at least one being still clottable. Our results exemplify loss of intact fibrinogen with persisting anti-fibrinogen reactive FDP during STK therapy. Discrepancies in aca versus Data-Fi results may be due to ways in which FDP interact with different methods--fibrometer versus turbidimetric.

Adult↗