Biomedical subjects

L Diaz-Flores

Publications and source records attributed to L Diaz-Flores.

At least 19 recordsLinked to original sources

PubMed2001

Prognostic significance of Ki-67 nuclear proliferative antigen, bcl-2 protein, and p53 expression in follicular and diffuse large B-cell lymphoma.

We analyzed 104 patients with non-Hodgkin's lymphoma, follicular or diffuse large-B-cell-type lymphoma, in order to evaluate the correlation between clinical characteristics and immunohistochemical parameters. Immunostaining was performed by means of monoclonal antibodies against Ki-67, bcl-2, and p53 expression. Forty-nine of the patients showed follicular lymphoma. A high expression of bcl-2 was found in 93%, high expression of p53 in 57%, and low expression of Ki-67 in 96%. Follicular lymphoma grade III showed a p53 expression (p = 0.07) slightly higher than follicular lymphoma grades I and II, not reaching statistical significance. Follicular lymphoma grades I and II tended to express lower Ki-67 and higher levels of bcl-2 expression than grade III (p = 0.06). Fifty-five cases showed diffuse large-B-cell lymphoma. Among them, bcl-2 was absent in 39%, whereas p53 and Ki-67 expression were high in 38%. In the diffuse large-B-cell lymphomas, a high bcl-2 expression correlated with stages III and IV (p = 0.03) and involvement of more than one extranodal area (p = 0.03). High Ki-67 expression was also associated to extranodal involvement of more than one area (p = 0.03). Overall survival of patients did not show statistically significant differences regarding Ki-67, bcl-2, and p53 tumoral expression. Prognostic factors for overall survival in the multivariate analysis were age (p = 0.02) and LDH (p = 0.003). Time to progression was worse among follicular lymphoma with high p53 expression than with mild/moderate p53 expression (p = 0.009).

Adult↗

PubMed2000

Cutaneous primary paracoccidioidomycosis.

Paracoccidioidomycosis is a common fungal infection in Latin America. Few cases have been described in non-endemic countries and their diagnosis without the correct suspicion, bearing in mind that the latency period might be up to 60 years, may not be easy. We report the case of a 59-year-old man who worked as a taxi driver for 25 years in Venezuela. Cutaneous paracoccidioidomycosis was diagnosed one year after he returned to Spain. No internal signs or symptoms of the disease were found and cell-mediated immunity showed no depression. Our case suggested us to consider direct cutaneous infection, although respiratory tract is believed to be the most frequent portal of entry for this infection.

Humans↗

PubMed1999

Tryptophan ingestion by pregnant rats induces pituitary and mammary tumours in the adult female offspring.

The present study was designed to evaluate the long-term consequences of tryptophan treatment on the central serotonergic activity in the female offspring of rats, and particularly on serotonin-controlled hormone release. During the second half of gestation, tryptophan (200 mg/kg/day) was given daily by stomach intubation to pregnant rats and the brain concentrations of serotonin and 5-hydroxyindole acetic acid and the plasma concentrations of prolactin, progesterone, oestradiol and luteinizing hormone were quantified in the adult female offspring. The offspring showed an increase in hypothalamic serotonin and serum progesterone and prolactin. In addition, maternal ingestion of tryptophan induced a marked rise in 665-day-old offspring in the incidence of both pituitary prolactinomas (62%) and mammary adenomas (49%). Present data suggest that tryptophan regulates serotonergic differentiation during early development. A transitory modification of the tryptophan concentration in the fetal brain induces a permanent increase in hypothalamic serotonin level and, in addition to modifying the release of prolactin, increases the incidence of tumours in the hypophysis and mammary gland.

Animals↗

PubMed1999

Malignant rhabdoid tumor beside benign skin mesenchymal neoplasm with myofibromatous features.

Only a few reports of primary cutaneous rhabdoid tumors have been published. We describe the case of a 3-month-old female patient who developed a rhabdoid type cutaneous sarcomatoid neoplasm in her upper back, close to a benign myofibromatous proliferation of infancy. The lesion was studied both by light microscopy and immunohistochemically. Flow cytometry was performed showing a DNA diploid profile of the malignant tumor. The pathological findings suggest a mesenchymal origin (hemangiopericytic or myofibroblastic type) for both tumors. The patient was surgically treated, but she died nine months later.

Biomarkers, Tumor↗

PubMed1996

Induction of neovascularization in vivo by glycerol.

Glycerol, injected into a site between the femoral vessels of the rat, induced neovascularization, both from the preexisting microcirculation and from the side of the femoral vein facing the artery-vein interstitium where the glycerol was administered. The use of glycerol together with a known angiogenic substance (PGE2) did not modify the neocapillary density (NCD) obtained with glycerol alone. In contrast, the lower level of NCD achieved with an acylglycerol (triacetylglycerol) was increased when the latter was associated with PGE2. Values reached were similar to, but never higher than, those for glycerol alone, or combined with PGE2. The results suggest that glycerol and some substances containing glycerol, amongst which 1-butyrylglycerol has been previously considered, may stimulate angiogenesis by a direct or indirect mechanism of action.

Animals↗

PubMed1994

Intense vascular sprouting from rat femoral vein induced by prostaglandins E1 and E2.

The formation of new capillaries from the rat femoral vein was specifically explored to assess whether venous vessels of this caliber may participate in the process of angiogenesis. Prostaglandins of the E series (PGE1 and PGE2) were administered into the soft connective tissue surrounding the rat femoral vessels as angiogenic inducers. In these conditions, between 2 and 7 days, a great number of new capillaries were observed in the media of the femoral vein, arising from the endothelial cells (EC) in the intima. The events of the capillary growth from the femoral vein included EC activation, local degradation of the basal membrane followed by migration and proliferation of EC, solid sprout formation with posterior canalization, development of a new basal membrane, and appearance of pericytes around the new capillary. Although numerous vascular buds were also observed arising from the small venules and capillaries in the periadventitial tissues, they were separated at first from those in the media of the femoral vein by the venous adventitia. Later, connections were observed between both newly formed microcirculations. The present study shows the capacity of PGE1 and PGE2 in the extravascular position of inducing capillary sprouting from veins. Furthermore, the observations provide greater evidence that vessels with characteristics similar to those of the rat femoral vein may contribute to angiogenesis, on occasion with an intense neovascularization. This fact may be of interest for the establishment of a functional circulation after angiogenesis by anastomoses of the new capillaries with those arising from pre-existing vessels of greater caliber than the venules.

Alprostadil↗

PubMed1994

Macrophages and Schwann cells in myelin disintegration.

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Animals↗

PubMed1992

Behavior of postcapillary venule pericytes during postnatal angiogenesis.

Autogeneic bone marrow was implanted into an artificially created cavity in a segment of rat sciatic nerve, after removal of nerve fascicles, without damaging the epineurium or surrounding microcirculation. Under these conditions, the bone marrow induces capillary growth and forms granulation tissue from surrounding tissues, the behavior of pericytes being studied in the preformed (preexisting) postcapillary venules of the latter. Beginning 20 h after bone marrow implantation, the pericytes of the preexisting postcapillary venules hypertrophy, with shortening of their processes, prominent nucleoli, dispersal of ribosomes into their free form, fragmentation of basal lamina, and increased DNA synthesis. The number of contact surfaces between pericytes and endothelium is noticeably lower than in controls. Many pericytes are in mitosis. Cells with a shape transitional between pericytes and interstitial fibroblast-like cells appear. In some cases, Monastral Blue (MB) was used as a marker of the cells in preexisting venule walls of the graft bed. In the earlier stages of the experiment, the MB labelling is restricted to the cytoplasm of pericytes and endothelial cells of postcapillary venules, and to the macrophages that occur in the space between pericytes and endothelium. Furthermore, the marker continues to be observed, at a later stage, in some of the following cells: pericytes and endothelial cells of the newly formed vessels, macrophages migrating into the interstitium, transitional cells between pericytes and fibroblasts, and typical fibroblasts of the granulation tissue. The present study provides greater evidence that preformed microvasculature pericytes are substantially activated during postnatal angiogenesis and granulation tissue formation, suggesting that they may contribute to the origin of new pericytes and fibroblasts.

Aging↗

PubMed1992

Ito cells and fibrogenesis in chronic alcoholic liver disease.

The relationships between the number of Ito cells; serum N-terminal type III procollagen and laminin; clinical and biochemical parameters of liver function derangement; histomorphometrically assessed total amount of liver fibrosis; and daily ethanol intake were studied in 43 patients affected by chronic alcoholic liver disease (10 cirrhotics). Significant correlations were found between serum laminin and N-terminal type III procollagen and histological, clinical and biochemical data of liver function derangement, but no correlation was found between the aforementioned parameters and the percentage of Ito cells, which in turn seemed to be related to ethanol ingestion.

Adipose Tissue↗

PubMed1992

Pericytes as a supplementary source of osteoblasts in periosteal osteogenesis.

In the adult rat femur, lifting a periosteum strip with microscopic bone flakes on its deep surface, if performed without damaging the surrounding microcirculation, rapidly leads to new bone formation and angiogenesis. Using vascular labeling, the pericytes and endothelial cells (ECs) were labeled with monastral blue (MB) in the preformed, preexisting postcapillary venules of the periosteal microcirculation. MB was detectable by light and electron microscopy and it persisted in some of the daughter cells. Between one and 21 hours, the MB labeling was restricted to the pericytes and ECs of postcapillary venules. Immediately afterward, both pericytes and ECs of these vessels were activated and continued to show MB. The phenomenon of pericyte activation includes enlargement, disruption of their basal lamina, separation from the walls of the preformed vessels, and the presence of mitotic figures. At this stage, activated pericytes with MB in their cytoplasm, fibroblast-like cells, and transitional cell forms between them were seen in interstitial areas. After 27 hours, vascular buds appeared and MB was detected in some ECs and pericytes. Between three and six days, when bone-tissue development was observed, some osteoblasts were MB labeled. Previous findings support the hypothesis that when the periosteum is activated, the process of bone formation from cells already present in the periosteum is augmented by proliferation and differentiation of pericytes, which contribute a supplementary population of osteoprogenitor cells.

Animals↗

PubMed1991

Inducible perivascular cells contribute to the neochondrogenesis in grafted perichondrium.

Autogeneic perichondrium was implanted above the cremaster muscle of the rat, and the new formation of two types of cartilage (types I and and II) was confirmed. Also, granulation tissue was observed before the type II cartilage formation. Under these conditions, the contribution to the neocartilage of graft bed derived cells, mainly of the venule pericytes, was studied. To follow the pericyte lineage, we used a marker--Monastral Blue B--the administration of which was based on the principle of vascular labeling. While the perichondrium was kept free, before its implantation, the preformed (preexisting) venules in the cremaster muscle were exclusively labeled with Monastral Blue B, which was incorporated into the cytoplasm of pericytes and endothelial cells. After perichondrium implantation, the following sequence in tracer distribution was demonstrated. During the earlier stages, labeling was restricted to the pericytes and endothelial cells of venules in the graft bed. Later the tracer was observed in some endothelial cells and pericytes of the growing vessels and in fibroblast-like cells of the granulation tissue. Finally, some type II neochondrocytes appeared labeled. Tracer was not found in type I neochondrocytes. The presence of label in type II neochondrocytes demonstrates that they arise from progenitor cells present in the graft bed, principally from small venule pericytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Proliferative fasciitis: ultrastructure and histogenesis.

The ultrastructure was studied of 2 cases of proliferative fasciitis (PF) which affected the fascia and subcutaneous fat. Two basic cell types were observed in the lesions: fibroblast-like, and giant cells. The fibroblast-like cells had myofibroblastic ultrastructural characteristics. The giant cells showed a well-developed, rough endoplasmic reticulum, irregularly distributed filaments and clear lipid droplets in their cytoplasms. Ultrastructurally, the giant cells seemed to belong to a cellular line capable of synthesizing ground substances and extracellular fibers, but with a modified phenotype. A consistent feature was the presence of nodular aggregates of numerous proliferating perivascular cells. Transitional forms between perivascular, fibroblast-like, and giant cells were observed. Our hypothesis is that perivascular cells (activated pericytes) are the source of the fibroblast-like and giant cells in proliferative fasciitis.

Fascia↗

PubMed1988

Growth of two types of cartilage after implantation of free autogeneic perichondrial grafts.

The perichondrium of adult rats was dissected from the posterior side of the ear where a plane of separation can be easily found between the superficial chondrocytes and the rest of the cartilage. When pulled off, the perichondrium brings with it a cartilaginous strip adhered to its inner layer, with the detachment surface showing projections of broken capsular matrix (PBCM). The perichondrium and subperichondrial cartilage were then transferred as autogeneic grafts to preformed muscle pockets of the abdominal wall and to everted vein chambers placed free in the iliac blood flow. During a period of one to 12 days, chondrogenesis was studied in the grafts and in the graft bed areas next to subperichondrial cartilage. When the perichondrium was placed into a muscular pouch, wherein perichondrocytes survived and a prominent vascular ingrowth in the graft bed was observed, the presence of two types of newly formed cartilage was demonstrated (Types I and II). These types showed differences in their location, time of appearance, and microscopic characteristics. Type I neocartilage appeared in the inner layer of the perichondrium on the third or fourth day after grafting; at this time the cells, surrounded by a well-defined capsular matrix, were large, darkly stained, and highly electron dense. Type II neocartilage, separated from Type I by the PBCM, appeared in the graft bed area located within perichondrial folds on the sixth or seventh day after implantation. Their cells showed a poorly defined capsular matrix and were smaller, lighter stained, and less electron dense than those of Type I. When the perichondrium was transplanted to everted vein chambers placed in the iliac blood flow, wherein perichondrocytes survived and vascular ingrowth from the graft bed was not present, Type I neocartilage was formed but Type II was not. The morphologic and histoautoradiographic findings in these studies suggest that Type I cells come from perichondrocytes of the inner perichondrial layer, whereas Type II cells originate from the undifferentiated perivascular mesenchymal cells of the graft bed.

Animals↗

PubMed1985

Relation between arterial intimal thickening and the vasa-vasorum.

The histopathological data presented support a new concept for the origin of the cells which cause intimal thickening of arteries. Arterial segments, isolated between ligatures, when examined by intravascular contrast techniques, showed penetration of vasa-vasora and formation of intra-arterial granulation tissue which produced myointimal thickening. Transitional forms between pericytes and myointimal cells were found. In autoradiographic studies on the incorporation of 3H-thymidine, DNA synthesis was first seen in the adventitia, fundamentally in the vasa-vasora pericytes, and in the adjacent media, and later in the intimal thickening. In arterial segments between ligatures typical intimal thickening was produced when intra-arterial granulation tissue was formed and the ligatures were removed thus restoring the circulation. These results were not produced when the arterial segment was sectioned lengthways between ligatures. It is suggested that this intimal thickening originates in cells from the vasa-vasora, in particular from pericytes.

Animals↗

PubMed1985