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Biomedical subjects

W H Clark

Publications and source records attributed to W H Clark.

At least 145 records · Page 8Linked to original sources
PubMed1976

The developmental biology of induced malignant melanoma in guinea pigs and a comparison with other neoplastic systems.

Malignant melanoma has been induced in the Weiser-Maple guinea pig by prolonged application of 7,12-dimethylbenz(a)anthracene. The tumor shows a biphasic growth pattern analogous to the radial and vertical growth phase of human cutaneous malignant melanoma. It evolves through a predictable series of cellular events classified as intraepidermal melanocytic hyperplasia, dermal melanocytosis, dermal melanocytoma, malignant melanoma without intralesional transformation, and, finally, malignant melanoma with intralesional transformation, which is characterized by the appearance of "new kinds of cells" and is associated with widespread metastases and massive lymph node involvement. Clinically, the lesions evolve from diffuse hyper-pigmentation to brown-black macules, to nodules of increasing size, to overt malignant melanoma associated with metastases, wasting, and death. Examples of intralesional transformation analogous to that in guinea pigs are found not only in human malignant melanomas, but in other human neoplastic systems, and such analogous cellular events are discussed in this paper.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Regression of pulmonary metastatic disease associated with intralesional BCG therapy of intracutaneous melanoma metastases.

A 77-year-old white man with 64 intracutaneous melanoma metastases and a pulmonary metastatic deposit was treated with immunotherapy. Over an 8-month period, 17 intracutaneous lesions were inoculated with BCG. All 17 injected lesions and all 47 uninjected intracutaneous lesions resolved; no new nodules appeared and the pulmonary metastasis regressed (greater than 50%). This is the first documented case of a pulmonary metastatic focus responding to intralesional BCG therapy of intracutaneous metastases.

Aged↗
PubMed1975

Lattice and rodlet nuclear inclusions in Merkel cells in rabbit epidermis.

A latticee or rodlet inclusion is occasionally observed in the nucleus of a Merkel cell. The lattice has the external form of a plaque or band and internally consists of alternating parallel wide and narrow layers. Filaments in wide layers run in at least two directions across the short dimension of the inclusion. In contrast, the rodlet is a bundle of parallel filaments running the long dimension of the inclusion. Filaments in lattices and rodlets possibly contract and agitate the highly folded nucleus of the Merkel cell.

Animals↗
PubMed1975

The clinical diagnosis of malignant melanoma.

The diagnosis of malignant melanoma thus rests upon an appreciation of sometimes subtle but definite signs detectable by careful observation of color, border, and surface of the lesions. Differential diagnosis lies among several cutaneous lesions, neoplastic and nonneoplastic. At times the lesions that are most difficult to distinguish from malignant melanomas are certain pigmented basal cell carcinomas, thrombosed hemangiomas, and certain types of moles. An attempt has been made in this review to describe and illustrate those features of pigmented lesions that are most helpful in diagnosis.

Basal Cell Carcinoma↗
PubMed1975

The developmental biology of primary human malignant melanomas.

We have attempted to describe virtually all forms of malignant melanoma which affect man except those arising in the eye. The vast majority of malignant melanomas clearly fall into one of three kinds: (1) malignant melanoma of the superficial-spreading type, (2) malignant melanoma of the lentigo-maligna type, and (3) malignant melanoma of the nodular type. The developmental biology of a primary neoplasm is illustrated by discussing and illustrating the evolution of these three dominant forms of melanoma. Primary malignant melanoma of the superficial-spreading type and of the lentigo-maligna type develop through a characteristic biphasic growth pattern: an initial radial-growth phase, followed by a vertical-growth phase. The radial-growth phase of these melanomas is only rarely associated with the development of metastases, while the vertical-growth phase is commonly associated with subsequent metastatic disease. The phenomenon of the vertical-growth phase is apparently, therefore, a qualitative step in the development of a primary malignant melanoma. Malignant melanoma of the nodular type is an example of a primary tumor without a precursor developmental stage such as a radial-growth phase.

Adult↗
PubMed1974

A fine structural investigation of surface specializations and the cortical reaction in eggs of the cnidarian Bunodosoma cavernata.

Developing oocytes of the cnidarian Bunodosoma cavernata are located within the mesoglea of the mesenteries of the gastrovascular cavity. The cortex of the more mature vitellogenic oocytes contains numerous, electron-dense, membrane-bound, cortical granules. The surface of these oocytes possesses prominent radially projecting structures termed cytospines. Each cytospine has a core of microfilaments, 50-70 A in diameter, that extends basally as a rootlet through the cortical layer. During spawning, ova lacking any extraneous investments are released from the enclosing gastrodermis. As a consequence of fertilization or events associated with the earliest stages of development the ova undergo a massive cortical reaction. This reaction, which occurs during or just after release of the ova, involves extensive reorganization of the cortical layer. The cortical granule membranes and egg surface membrane fuse and vesiculate resulting in the massive discharge of granule contents. This event is accompanied by the loss of vesicular remnants of cortical ooplasm and the disruption of cytospine organization. Light and electron microscope comparisons of unreacted and reacted eggs show that the reaction results in a significant decrease in egg diameter with the oolemma of the reacted egg reorganizing in a position centripetal to its original location.

Animals↗
PubMed1974

Cardiac rupture.

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Aged↗