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C De La Torre

Publications and source records attributed to C De La Torre.

9 recordsLinked to original sources
PubMed2002

Modelling complex populations formed by proliferating, quiescent and quasi-quiescent cells: application to plant root meristems.

A proliferating population of cells may be considered complex when its proliferative or growth fraction P is lower than 1 and/or when it is formed by subpopulations with different mean cycle times. The present paper shows that in such complex populations exponential growth is consistent with a steady-state distribution of cells. Obviously, when P=1 then cell distribution is only a function of cell age. An analytical model has been developed to study complex populations including both quiescent fractions formed by cells with unreplicated genome (G(0) cells) and cells with fully duplicated chromosomes (Q(2) cells). The model also considers those quasi-quiescent cells in their last transit through G(1) and S (Q(1) and Q(s) cells) before becoming quiescent. In order to solve the difficulties of a direct analysis of the whole population, its kinetic parameters have been obtained by studying the negative exponential distribution of two subpopulations: one formed by the proliferating cells and another formed by the quasi-quiescent cells. Additionally, the model could be applied when quiescence is initiated at any other cycle phase different from G(1) and G(2), for instance, cells in the process of replicating their DNA or being at any other mitotic phases. The utility of the method was illustrated in populations which constitute the root meristems of both Allium cepa L. and Pisum sativum L. Three facts should be stressed: (1) the method seems to be rather powerful because it can be carried out from different sets of experimentally measured parameters; (2) the rate of division and, therefore, the population doubling time can be easily estimated by this method; and (3) it also allows the determination of the amount of cells that had become quiescent either before they had replicated their DNA (G(0)) or after having completed their replication (Q(2)), as well as those quasi-quiescent cells which are progressing throughout their last pre-replicative and replicative periods (thus Q(1) and Q(s), respectively).

Allium↗
PubMed2001

Sea-urchin granuloma: histologic profile. A pathologic study of 50 biopsies.

BACKGROUND: Sea-urchin granuloma is a chronic granulomatous skin lesion caused by injury with sea-urchin spines. Frequently these lesions occur on the hands and develop several months after the initial injury. Classified as an allergic foreign-body reaction, their most common histological pattern resembles sarcoid. The purpose of this study was to evaluate the light microscopic features of biopsies from lesions clinically diagnosed of sea-urchin granolomas. METHODS: We retrospectively reviewed 50 biopsy specimens corresponding to 35 patients with sea-urchin granulomas. These lesions were caused by injuries with the spines of the sea-urchin Paracentrotus lividus. Data were collected between 1990 and 1999 from patients in the seashore of Galicia (NW Atlantic coast, Spain). RESULTS: The cohort consisted of 35 patients (31 males, 4 females), with a median age of 35 years (range 14-60 years). The median duration of the disease was 7.5 months (range 2-60 months). We identified different histopathologic patterns. A granulomatous reaction was observed in 39 biopsies (78%). In 70% corresponding to 35 biopsies this granulomatous reaction was predominant. Foreign-body, sarcoidal, tuberculoid, necrobiotic and suppurative granulomas were identified. The remaining 15 biopsies (30%) showed a predominant inflammatory reaction with features of non-specific chronic inflammation or suppurative dermatitis. A panel of histopathologic features, including epidermal and dermal changes were evaluated. Presence of focal necrosis and microabscesses were common findings. In 50% of our specimens we found umbilication and/or perforation. Additional features included the presence of inclusion epidermoid cysts in four cases and squamous syringometaplasia in one case. CONCLUSIONS: Our observations suggest that sea-urchin granuloma span a wide morphologic spectrum. A granulomatous inflammatory reaction was predominant, with the foreign body and sarcoidal types the most frequent patterns. Other histopathologic patterns with non granulomatous inflammation can be noted. Some features, such as the frequency of perforation and the presence of necrobiotic granulomas have not previously been recognized in the literature.

Adolescent↗
PubMed2000

Sequelae after nasal septum injuries in children.

OBJECTIVE: To study the results of surgical treatment and sequelae in nasal septum injuries in children. METHODS: Between January 1990 and December 1997, 16 pediatric patients with septal haematoma and/or abscess were treated. Mean age was 5 years (range: 2-14 years). Thirteen were male (81.2%), and three were female (18.8%). In nine cases (56.2%) the disease was a consequence of a minor trauma. Only two children had nasal fracture associated (12.5%). Minimum follow-up after the first visit was 10 months (mean, 3 years). RESULTS: All cases were surgically treated. Minor sequelae were observed in six cases (37.5%), and major ones in ten patients (62.5%). In this latter group, multiple reconstructive procedures were needed. CONCLUSIONS: It is necessary to be aware of the possibility of haematoma and abscess of the nasal septum. Major sequelae can be also expected after cases following minor traumas.

Abscess↗
PubMed1998

Infantile pyramidal protrusion as a manifestation of lichen sclerosus et atrophicus.

BACKGROUND: A perineal infantile lesion previously described as "skin tag/fold" had recently been named infantile perianal pyramidal protrusion. It appears on the perineal median raphe of girls as a pyramidal soft tissue swelling, covered by smooth, red or rose-colored skin. Its pathogenesis is unknown. As in the case of other perianal lesions, knowledge about it is important, as concern about signs of child abuse grows. OBSERVATIONS: Four girls, 2 of them sisters, with infantile perianal pyramidal protrusion were studied. Three of these girls showed subtle clinical evidence of classic lichen sclerosus et atrophicus on first examination. The other girl developed vulvar lesions of lichen sclerosus et atrophicus months after the diagnosis of infantile perianal pyramidal protrusion. All 4 protrusions disclosed histopathological findings diagnostic of lichen sclerosus et atrophicus. CONCLUSIONS: Infantile perianal pyramidal protrusion is, at least in some patients, a peculiar form of lichen sclerosus et atrophicus that can precede other, more characteristic manifestations. We suggest changing the name to the more precise infantile perineal protrusion. Knowledge of this hitherto unrecognized clinical form of lichen sclerosus et atrophicus can help to explain anogenital symptoms and avoid its misinterpretation as a sign of sexual abuse.

Child↗
PubMed1992

Effect of caffeine and isobutyl-methyl-xanthine on production of binucleate cells and on post-replicative repair.

Caffeine (CAF) but not 3-isobutyl 1-methyl-xanthine (IBMX) displayed a strong DNA anti-repair effect in G2 prophase, as estimated by the frequency of abnormal chromosomes in anaphase-telophase found shortly after treatment. IBMX is more effective than CAF in inhibiting cytokinesis, while the binucleate cells formed by a short treatment with any of these two xanthines have similar cycle kinetics.

1-Methyl-3-isobutylxanthine↗