Search PubMed⌕ Search

Biomedical subjects

R Caputo

Publications and source records attributed to R Caputo.

At least 181 records · Page 10Linked to original sources
PubMed1982

A freeze-fracture study of the human nail plate.

This study of freeze-fracture replicas of human nail plate fragments demonstrates that keratin filaments have a width of about 100 A. The 'marginal band' is probably formed by a row of particles, 50 A in diameter, arranged along the inner surface of the plasma membrane. These particles are often masked by keratin filaments. In nonjunctional areas, the plasma membranes are devoid of membrane-associated particles. The only type of junction observed is the desmosome. Even though the modes of keratinization are different, the structures of the keratin pattern, of cell membranes, and of the desmosomes are identical in replicas of wholly keratinized nail and human stratum corneum cells. The ultrastructural differences observed appear to be related to the barrier function carried out by the epidermis and by its desquamation process.

Adult↗
PubMed1982

Freeze-fracture replication technique of human skin.

The freeze-fracture replication technique represents one of the most advanced methods for studying the ultrastructure of biological tissues and has given a new dimension to the ultrastructure research. This technique makes it possible to obtain a cast of a fracture surface of frozen preparations. Apart from allowing samples to be examined without being dehydrated, i.e. under conditions very close to those of living state, it has proved especially useful for the analysis of many tissue functions concerned with membrane activity and exchanges between cells and their disturbance in specific disease conditions. Even through good quality replicas had already been obtained back in 1961 (Moor et al. 1961), only after 1970, mainly thanks to the contribution made by Breathnach and his collaborators (Breathnach et al. 1972, Breathnach 1973, Breathnach et al. 1973) was the freeze-fracture replication technique successfully used in the study of the skin, since this tissue had proved especially difficult to process. In this review paper, technical principles will be summarized and the most important findings so far obtained in the study of normal and pathologic skin will be illustrated.

Cell Membrane↗
PubMed1982

Insulin resistance in a child with Acanthosis nigricans type A.

The patient, a female 6 years 4 months old, diagnosed as affected by Acanthosis nigricans and diabetes mellitus was referred to our Clinic for further investigation of her glucose metabolism. She had a typical face with hypertelorism, prognathism, macroglossia and large auricles. The skin was hyperpigmented, verrucous, hyperkeratotic especially in the folds and flexural areas with small papillomatous or nodular growth; diffused hypertrichosis and hypertrophic clitoris were also present. Biochemical and hormonal investigations revealed no major abnormalities apart from glucose metabolism. After an unsuccessful trial with conventional insulin therapy, endovenous continuous insulin infusion was started: even with 32 U/kg/h it was not possible to achieve normoglycemia. Insulin receptors were studied on erythrocytes: 125I-insulin binding (specific) was clearly lower than normal. The concentration of insulin receptors was reduced, while the average affinity profile was normal. The study of erythrocyte insulin receptors has demonstrated that insulin resistance in this patient is due to a decrease in the number of receptors, i.e. Acanthosis nigricans type A.

Acanthosis Nigricans↗
PubMed1982

Congenital self-healing histiocytosis.

In a typical case of congenital self-healing histiocytosis of the Hashimoto-Pritzker type, the results of an ultrastructural examination of a nodule of a 30-day-old patient showed that about 25% of the cells contained unique phagosomes but no regularly laminated bodies. This case of congenital self-healing histiocytosis is an example of concurrent proliferation of two types of histiocytes (one with and one without Langerhans' granules). Since transitional forms were not observed, this finding might indicate the existence of congenital, self-healing forms of histiocytosis X.

Cytoplasm↗
PubMed1981

Generalized eruptive histiocytoma. A clinical, histologic, and ultrastructural study.

A case of adult self-healing histiocytosis, classified as generalized eruptive histiocytoma, is reported. Ultrastructural investigation of the cytoplasm of tumor cells revealed the presence of many dense and laminated bodies. The origin and possible importance of these bodies are described and discussed, and the need for quantitative study of cytoplasmic markers in histiocytic proliferations of the skin is emphasized.

Adult↗
PubMed1981

Collagen phagocytosis in multicentric reticulohistiocytosis.

A large number of dermal cells engaged in collagen phagocytosis were observed in a case of multicentric reticulohistiocytosis. These cells apparently start to engulf collagen by deep invaginations of the plasma membrane. Fusion of phagosomes containing the engulfed collagen with vesicles probably originating from the Golgi apparatus would give rise to secondary lysosomes. The process of collagen degradation leads to the appearance of fine fibrils and myelin bodies. The presence in the dermis of unusually thick collagen fibers might contribute to this process which appears to occur only under particular physiological and pathological conditions.

Cell Membrane↗
PubMed1980

GAp junctions in skin tumors of molluscum contagiosum.

Thin section, tracer, and freeze-fracture experiments demonstrate that the infection caused by molluscum contagiosum virus implies alterations of cellular contacts in the epidermis, never before observed in cutaneous viroses. These changes are basically represented by a distinctive variation in particle packing of gap junctions, a greater proliferation of these junctions and the presence of a high amount of intracytoplasmic gap junctions. Skin tumors caused by molluscum contagiosum virus appear to be a convenient model to study the morphological and topological variations as well as the turnover of gap junctions in the epidermis.

Freeze Fracturing↗
PubMed1980

Internal organization of plasma membranes during the acantholytic process. A freeze-fracture study.

The internal organization of plasma membranes was studied in seven subjects with pemphigus vulgaris and in one subject with familial pemphigus using the freeze-fracture technique. The results obtained seem to suggest that the acantholytic process is produced in a similar fashion whatever the pathogenic agent and that desmosomes represent the "target" membrane specializations in the acantholytic phenomena. The reduction and eventual disappearance of desmosomal particle aggregations is seemingly accompanied by an increase in gap junctions.

Acantholysis↗
PubMed1978

Plasma membranes in psoriatic cells. A freeze-fracture study.

A freeze-fracture study of affected and unaffected psoriatic skin has demonstrated the presence of marked modification of the plasma membrane in the psoriatic lesion. In the lower layers of the epidermis, an increase of membrane associated particles was observed in many keratinocytes, possibly representing the morphological intramembranous equivalent of changes in the outer cell membrane demonstrated with cytochemical techniques. Furthermore, in the malphighian layer, numerous gap junctions have been found, which may be interpreted as a phenomenon compensating the uncontrolled proliferation, and may represent a point of differentiation between cell proliferation in psoriasis and neoplasia. This technique confirmed the poor tendency to adhesion of keratinocytes in extrajunctional areas, which had already been shown by other morphological techniques.

Adult↗
PubMed1977

A unique cytoplasmic structure in papular histiocytoma.

Intracytoplasmic granules with a unique and highly complex ultrastructure, have been observed within the cellular infiltrate of the lesions of two patients with papular histiocytosis. Examination of serial sections has enabled construction of a three-dimensional model of these granules, which appear to be composed of an elaborate arrangement of membranes and vesicles. Two hypotheses (endocytosis and exocytosis) are proposed for the mode of formation of these unique cytoplasmic structures.

Adolescent↗
PubMed1977

Drug-induced changes in the plasma membrane of Microsporum canis. A preliminary freeze--fracture study.

Commercial solutions of clotrimazole, tolnaftate and tolcyclate were tested for 12 h in cultures of Microsporum canis. They induced modifications in particle distribution, a blebbing of particle-free areas and the appearance of lamellar figures on the plasma membrane of fungus cells. The first two changes in the plasma membrane might be ascribed to a modification of the spectrin-like meshwork, while the third could be the result of a crystalline organization of membrane lipids.

Antifungal Agents↗
PubMed1976

Freeze-fracture of Langerhans granules. A comparative study.

A comparative study of freeze-fracture replicas and thin sections of Langerhans granules has proved that the effects of conventional tissue processing on the inner structure of the granule are negligible, and the study has confirmed the validity of the previously proposed tridimensional models. The paracrystalline quality of the substance contained between the limiting membranes of the disc-shaped area of the granules seems to suggest it protein nature. In replicas, no particle organizations attributable to intercellular junctions were observed on the plasma membranes of Langerhans cells.

Cell Membrane↗