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Biomedical subjects

F Contreras

Publications and source records attributed to F Contreras.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nonscarring alopecia associated with solitary circumscribed neuroma.

We report an unusual case of nonscarring alopecia clinically resembling patchy alopecia areata around central solitary circumscribed neuroma. Prompt and spontaneous complete hair regrowth was observed after removal of the tumor. Further knowledge of growth factor and receptor interaction in regulating the hair follicle cycle, as well as on the production of growth factors and cytokines by tumor cells and/or cells within the tumor microenvironment may contribute to better understand the pathologic mechanisms underlying certain curious phenomena such as peritumoral nonscarring alopecia.

Aged↗
PubMed1997

High incidence of porokeratosis in renal transplant recipients.

Immunosuppression is a well-documented precipitant of porokeratosis (PK). However, PK is not considered among the most common cutaneous disorders in immunosuppressed patients. We studied prospectively a series of 103 renal transplant patients and found 11 cases (10.68%) of PK. Our series represents the highest incidence of PK in transplant patients reported so far. Our findings suggest that PK in transplant recipients may be more frequent than previously thought.

Adult↗
PubMed1997

Solitary corneal myxoma.

PURPOSE: To report the clinicopathologic findings of a myxoma that arose in the subepithelial region of the right cornea of a 53-year-old man 4 years after successful treatment of an infectious corneal ulcer. METHODS: Histopathologic and histochemical evaluation of corneal tissue. RESULTS: This rare lesion appears to have originated from corneal stromal fibroblasts that reacted to an inflammatory stimulus and produced excessive amounts of glycosaminoglycans (hyaluronic acid) rather than normal collagen. CONCLUSION: Myxoma formation may require interruption of Bowman's layer and proximity of the scar to the epithelium.

Cornea↗
PubMed1996

Growth hormone response to growth hormone releasing hormone in non-delusional and delusional depression and healthy controls.

Growth hormone (GH) responses to growth hormone releasing hormone (GHRH) of 53 in-patients meeting DSM-III-R criteria for major depressive episode with melancholia (24 non-delusional and 23 delusional depression) were compared with those of 19 healthy controls. No significant differences in basal GH were found between the control and either the non-delusional or the delusional groups. The whole group of depressed patients showed a significantly lower response than the control patients at all points of the GH response to GHRH curve as well as a lower area under curve. When the three groups (control, delusional, and non-delusional depressed) were compared, it was found that only the non-delusional depressed patients had a significantly lower area under curve and lower values at +60, +90 and +120 min than the controls. The only significant difference between the two groups of depressed patients was that the delusional group showed a delayed appearance of the maximum response peak and a more prolonged response.

Adult↗
PubMed1996

Neural variant of fetal rhabdomyoma and naevoid basal cell carcinoma syndrome.

A 15-year-old boy with the characteristic features of the naevoid basal cell carcinoma syndrome presented with a retroperitoneal mass. The tumour showed morphological features of a still ill-defined variant of fetal rhabdomyoma, characterized by well-differentiated nerve fibres admixed with immature striated muscle cells, similar to neuromuscular choristoma. Four cases of fetal rhabdomyoma and naevoid basal cell carcinoma syndrome have been previously reported. The behaviour of this tumour has been benign, although a complete excision was impossible due to its close relation with abdominal vascular trunks.

Adolescent↗
PubMed1996

[Nutrients in 39 Mexican coastal lagoons].

An analysis of 39 Mexican coastal lagoons most in tropical environments, shows no nutrient limitation for primary productivity: even minimum nutrient values are higher than those of similar systems (mostly of temperate zones). In some cases, nutrient variations are large and indicative of heterogeneity. The N:P ratio is more important than simple nutrient concentrations. Using this ratio, coastal lagoons are classified as limited in nitrogen (< 5) or phosphorus (> 10).

Mexico↗
PubMed1995

Differential patterns of placental and epithelial cadherin expression in basal cell carcinoma and in the epidermis overlying tumours.

P-cadherin (P-CD) and E-cadherin (E-CD) are expressed by keratinocytes and play an important role in skin morphogenesis. P-CD expression is restricted to the basal layer of normal epidermis, whereas E-CD is expressed in all the living layers. We have previously reported a reduced expression of E-CD in most cases of infiltrative basal cell carcinoma (BCC). In the present work we have investigated by immunohistochemistry the expression of both P-CD and E-CD in a new series of 32 patients with BCC. Most cases of superficial multicentric BCC and some nodular tumours had preserved expression of both cadherins in all tumour cells. The majority of nodular BCCs had partially reduced expression of one or both cadherins with an ordered distribution of cells showing different cadherin staining throughout the tumour mass. A severe reduction of E-CD expression with a disordered distribution of cells with different immunostaining intensity was observed in most specimens of infiltrative BCC. In contrast, P-CD expression was preserved in all cases of infiltrative BCC. These results suggest that P-CD and E-CD play different roles in the growth pattern of BCC. In addition, both anomalous P-CD expression and reduced E-CD expression were frequently observed in the spinous layer of epidermis overlying tumours. This phenomenon was significantly associated with the presence of keratinocytic atypia, which suggests that disturbed cadherin expression could be a marker of premalignant changes and/or hyperproliferative activity in human epidermis.

Aged↗
PubMed1995

p53 protein expression in viral warts from patients with epidermodysplasia verruciformis.

The p53 protein is the product of a tumour suppressor gene, which is implicated in many human malignancies. p53 expression was investigated by immunohistochemistry in a series of viral warts (n = 12) from five patients with epidermodysplasia verruciformis (EV), using a monoclonal anti-p53 antibody (DO7). p53 expression was also investigated in a series of common warts (n = 8), flat warts (n = 8), and penile bowenoid papulosis (n = 6) from non-EV patients. Immunostaining was positive in 11 of 12 (92%) EV warts, whereas p53 reactivity was negative in most cases of warts from non-EV patients. Exons 5-8 of the p53 gene were screened by the polymerase chain reaction-single strand conformation polymorphism technique in four EV warts, which were strongly stained for p53, and p53 mutations were not detected. These results suggest an association between p53 accumulation (probably of wild type) and EV warts.

Epidermodysplasia Verruciformis↗
PubMed1994

E-cadherin expression in basal cell carcinoma.

E-cadherin (E-CD) is a calcium-dependent cell-cell adhesion molecule which is expressed in almost all epithelial tissues. E-CD expression is involved in epidermal morphogenesis and is reduced during tumour progression of mouse epidermal carcinogenesis. It has been suggested that E-CD could play a role as an invasion-suppressor molecule. In the present work we have studied the E-CD expression in 31 patients with basal cell carcinoma (BCC) using an immunohistochemical technique with a monoclonal antibody (HECD-1) specific for human E-CD. E-CD expression was preserved in all specimens of superficial and nodular BCC, and was reduced in 10 of 15 infiltrative BCCs. A heterogeneous distribution of cells with different immunostaining intensity was more frequently observed in specimens of infiltrative BCC. These results suggest that E-CD might be related to the growth pattern and the local aggressive behaviour of BCC, and support the idea that E-CD might play a role as an invasion-suppressor molecule in vivo.

Adult↗
PubMed1994

Chondroid metaplasia in the tunica media of the aorta in dogs submitted to saphenous vein aorto-cava by-pass.

We submitted twelve dogs to aorto-superior vena cava by-pass with saphenous vein. Six months later, all dogs had developed areas of chondroid metaplasia in the tunica media of the aorta, near the area of anastomosis. Three dogs also had bony metaplasia. The Foci of metaplasia had no relation to sutures. This lesion begins with a build-up store of glycosaminoglycans in the tunica media. Later, elastic fibers show a fenestration and dissolution, while chondrocytes replace smooth muscle fibres. We suggest that the rupture of the vasa vasorum during operation and the traction and pulsation of the by-pass over the area of suture could be the cause of this direct metaplasia.

Anastomosis, Surgical↗
PubMed1993

Ophthalmic pathology laboratories in Latin America.

Ocular pathology laboratories have been one of the main reasons for the progress and evolution of ophthalmology in Latin America. This has been made possible through pathologic reports, meetings, and seminars and through the valuable help of basic teaching in residency programs in ophthalmology.

Clinical Laboratory Techniques↗
PubMed1993

Papular xanthoma in children: report and immunohistochemical study.

Papular xanthoma was diagnosed in a 14-month-old boy. The eruption cleared spontaneously within four years. Immunohistopathologic study revealed that the predominant foamy histiocytic cells had the phenotypic features of the dermal dendrocyte. Giant multinucleated cells, which showed characteristics of monocyte-derived macrophages, were also present. We suggest classifying diseases derived from dermal dendrocytes into a separate group of histiocytoses.

Giant Cells↗