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Biomedical subjects

D Casanova

Publications and source records attributed to D Casanova.

At least 55 records · Page 3Linked to original sources
PubMed2000

Amphotericin B inhibits the generation of the scrapie isoform of the prion protein in infected cultures.

Transmissible spongiform encephalopathies form a group of fatal neurodegenerative disorders that have the unique property of being infectious, sporadic, or genetic in origin. Although some doubts about the nature of the responsible agent of these diseases remain, it is clear that a protein called PrP(Sc) plays a central role. PrP(Sc) is a conformational variant of PrP(C), the normal host protein. Polyene antibiotics such as amphotericin B have been shown to delay the accumulation of PrP(Sc) and to increase the incubation time of the disease after experimental transmission in laboratory animals. Unlike for Congo red and sulfated polyanions, no effect of amphotericin B has been observed in infected cultures. We show here for the first time that amphotericin B can inhibit PrP(Sc) generation in scrapie-infected GT1-7 and N2a cells. Its activity seems to be related to a modification of the properties of detergent-resistant microdomains. These results provide new insights into the mechanism of action of amphotericin B and confirm the usefulness of infected cultures in the therapeutic research of transmissible spongiform encephalopathies.

Amino Acid Sequence↗
PubMed1999

Wound healing of human skin transplanted onto the nude mouse after a superficial excisional injury: human dermal reconstruction is achieved in several steps by two different fibroblast subpopulations.

It has been established that human skin grafted onto the nude mouse is able to regenerate after being subjected to a full-thickness wound. In the present work, we sought to determine the cells involved in the connective tissue repair process following superficial wounding. Two months after transplantation, superficial wounds were made at the center of the graft using mechanical dermabrasion. At various times thereafter, ranging from 2 days to 6 weeks, healing grafts were harvested and processed for immunohistological study with species-specific and cross-reacting antibodies directed against human or mouse antigens. The grafted human skin regenerated according to the following series of events. First, the human dermis underneath the scab became devoid of human fibroblasts while the surrounding human dermis preserved its own characteristics. The TUNEL reaction on earlyphase healing wounds indicated that apoptosis occurred steadily within this area and could be the mechanism by which cells disappeared. Moreover, cell death was reduced when the wound was covered with an occlusive dressing. The human dermis beneath the wound was then invaded by mouse cells which deposited type I collagen on the human extracellular matrix and produced mouse granulation tissue at the surface above it. Human keratinocytes migrated over the mouse granulation tissue to reconstruct the epidermis. Eventually, the mouse granulation tissue was progressively invaded by human fibroblasts, which formed a human neodermis. The overall process appeared to depend upon several successive epithelial-mesenchymal interactions, which were not species-specific. This suggests that myofibroblasts arise from a specific subpopulation of fibroblasts, probably located at the interface between the dermis and adipose tissue, and that the granulation tissue is eventually remodeled by another population of fibroblasts present in the human dermis.

Animals↗
PubMed1999

[Pseudo-paralysis of the brachial biceps in obstetrical brachial plexus lesions (OBPL):concerning the "overly optimistic" EMG in OBPL].

In birth palsy of the brachial plexus, the mixed interference pattern recorded for the brachial biceps on the electromyogram often conflicts with the muscle's inability to flex the elbow. We report our observations of a six-month-old infant who presented paralysis of the upper and medial elements of the brachial plexus, in whom we demonstrated early biceps-triceps co-contractions, which may explain this discrepancy and 'pseudo-paralysis' of the biceps. We analyse and discuss the practical consequences of these findings, and notably the possible therapeutic use of triceps-to-biceps surgical transposition.

Brachial Plexus↗
PubMed1999

Results and prognostic factors in stage I(E)-II(E) primary gastric lymphoma after gastrectomy.

BACKGROUND: Infrequency of gastric lymphomas and lack of homogeneity of studies dealing with them preclude accurate management schemes. Helicobacter pylori (HP) and Isaacson's classification are new factors to consider. Our aim was to analyze these and other prognostic factors in a homogeneous series. STUDY DESIGN: Fifty-four patients (mean age 62.4 years) treated by gastrectomy for primary gastric non-Hodgkin's lymphoma in stages IE or IIE were retrospectively reviewed. Twenty-seven patients received postoperative chemotherapy. HP and histologic features were studied using new slides from the paraffin-embedded gastrectomy specimens. RESULTS: Postoperative morbidity and mortality rates were 19% and 5.6%, respectively. Five-year survival was 83%. Classification showed low-grade tumors in 59% and high-grade tumors in 41%. HP was positive in 64% of the patients. A poorer survival was associated with high-grade tumors (p = 0.02) and serosa involvement (p = 0.02). We did not find any significant difference between patients treated either by partial or total gastrectomy (p = 0.2), or receiving chemotherapy or not (p = 0.9). Nor did we appreciate any differences concerning margin involvement (p = 0.9). CONCLUSIONS: Most primary gastric lymphoma patients have gastric HP. Serosa involvement and high-grade tumors adversely influence survival but gastrectomy type, resection margin invasion, and postoperative chemotherapy did not appear to have any influence.

Adult↗
PubMed1999

PAI-1 produced ex vivo by human adipose tissue is relevant to PAI-1 blood level.

Human adipose tissue has been shown to produce plasminogen activator inhibitor type 1 (PAI-1). However, the importance of adipose tissue in the regulation of the PAI-1 plasma level is not known. The aim of this study was to investigate the relation between the production of PAI-1 by adipose tissue, plasma PAI-1 level, and variables related to the insulin resistance state. The link between the production of PAI-1 inducers such as tumor necrosis factor-alpha and transforming growth factor-beta and the production of PAI-1 by adipose tissue was also evaluated. Blood samples were obtained as soon as possible to the induction of anesthesia from 30 patients undergoing elective abdominoplasty. PAI-1 antigen levels measured in conditioned media after a 19-hour incubation period of adipose tissue explants were significantly correlated with plasma PAI-1 antigen levels (r=0.54, P=0.004) and with systemic lipid parameters such as triglycerides and high density lipoprotein cholesterol (r=0. 46, P=0.014; r=-0.50, P=0.01, respectively) but not with insulinemia and body mass index. PAI-1 production by adipose tissue was correlated with those of TNF-alpha (r=0.5, P=0.01) and TGF-beta (r=0. 53, P=0.007). These results emphasize the role of adipose tissue in determining plasma levels of PAI-1, with a local contribution of TNF-alpha and TGF-beta in PAI-1 production by adipose tissue.

Adipose Tissue↗
PubMed1999

[Calcium supplementation and bone absorptiometry in girls].

BACKGROUND: The achievement of a peak bone mass is an important factor in the prevention of osteoporotic fractures. In normal children, the amount of calcium intake could affect bone mineral increment. AIM: To assess the effect of a daily 500 mg calcium supplement on bone mineral density, in a group of healthy Chilean girls. PATIENTS AND METHODS: Fifty healthy girls were studied and 25 were randomly assigned to receive a 500 mg calcium supplement during 10 months. Bone mineral density of the distal and ultradistal region of the forearm was measured in all girls by single X ray absorptiometry (Osteometer DTX-100) at the beginning and end of the study. Bone mineral density was expressed as Z values. RESULTS: Significant increments in bone mineral density at the distal radioulnar region were obtained in the supplemented girls. No significant changes in bone density were observed in control girls. CONCLUSIONS: A daily 500 mg calcium supplement for 10 months increased bone mineral density in healthy girls.

Absorptiometry, Photon↗
PubMed1998

Effects of radiation on endothelial function.

PURPOSE: The response of endothelium to ionizing radiation was studied. METHODS AND MATERIALS: The abdominal aorta in different experimental groups of rats was irradiated, and the response of arterial rings from the irradiated segments to norepinephrine, acetylcholine (ACh), and nitroglycerin (NTG) was studied. Nonirradiated thoracic segments in the same experimental animals were used as as a control for comparisons. Two age-matched nonirradiated control groups were also studied. RESULTS: A poor endothelium-dependent vasodilator response was obtained with ACh in the irradiated rings and also in those not directly irradiated; the endothelium-independent vasodilator response to NTG was preserved during the first 3 days after irradiation. By 6 months, both the endothelium-dependent response and endothelium-independent response were impaired. CONCLUSIONS: Alterations in nitric oxide synthesis and/or release by the endothelium were observed during the early phase of radiation in irradiated and nonirradiated segments. In the delayed phase of radiation, endothelium-independent muscular relaxation was also affected.

Acetylcholine↗
PubMed1998

Early curettage of giant congenital naevi in children.

Early curettage of giant congenital naevi in new-born infants, if performed during the first few weeks after birth, can have a substantial effect on the pigmentation of the lesions, reducing the number of pigmented cells and leaving only moderate scars. We describe our experience in a series of nine congenital naevi treated by curettage between the first and seventh week after birth. Histological changes that occur in the naevus during the first few days after birth mean that early treatment is needed to obtain a cosmetic improvement. Curettage as an early treatment for giant congenital naevi in new-born infants provides cosmetic improvement and might decrease the risk of malignancy; however, the lesions are not cured. Naevus cells persist in the deep dermal layers and may come to the surface, such that close monitoring is needed long after curettage. The cosmetic improvement is likely to benefit the child's psychological development.

Back↗
PubMed1998

[Prospective study of 100 cases of breast hypertrophy].

The authors performed a prospective study of 100 consecutive cases of mammary hypertrophy. Sixty were treated by McKissock's technique and forty by Thorek's technique. The patients were reviewed at the second and sixth postoperative months. A general study of the population was performed to specific their demand, which was functional in 90% of cases, and the various symptoms were quantified. 74% of cases presented with psychological problems and a desire for aesthetic improvement was expressed by 67% of cases. Postoperatively, a functional improvement was obtained in 99% of cases, while psychological disorders resolved in 100% of cases. The satisfaction rate was very high: 79% of patients were very satisfied and 20% were satisfied. Some defects observed by the patients or surgical team are analysed. The complications observed, always minor, are reported. Breast reduction provides an unquestionable benefit for patients with mammary hypertrophy. Two simple and perfectly defined techniques were used to treat all these cases with a maximal satisfaction rate and a minimal complication rate.

Adult↗
PubMed1998

Bone mineral density by single photon X-ray absorptiometry in Chilean children and adolescents.

OBJECTIVE: To assess bone mineralization in healthy Chilean children and adolescents, considering sex, age, height, and puberty. METHODS: In a descriptive cross sectional study, the appendicular bone mineral density (BMD) was measured by single photon x-ray absorptiometry at distal (D-BMD) and ultradistal (UD-BMD) regions of the forearm, in 571 healthy children and adolescents of Valparaíso and Viña del Mar, Chile, considering their age, sex, height, calcium intake, and pubertal development according to Tanner. RESULTS: Physical activity was regular; daily average calcium intake was 580 +/- 100 mg and the D-BMD and UD-BMD showed a 3 step growth pattern: Slow increments between 4 and 8 years of age in girls (r = 0.07 and r = 0.37, respectively) and between 4 and 12 years in boys (r = 0.17 and r = 0.39); sharp increases between 8 and 19 years in female adolescents (r = 0.78 and r = 0.73) and between 12 and 20 years in male adolescents (r = 0.82 and r = 0.67); and deceleration of growth from 19 years in female adolescents and 20 years in males. Considering Tanner classifications (T), boys had significant differences in mean D-BMD between T3 and T4 (p < 0.001) and between T4 and T5 (p < 0.001) and in mean UD-BMD between T3 and T4 (p < 0.001). They achieve higher values than women in adulthood. Girls showed significant differences in mean D-BMD between T3 and T4 (p = 0.003) and T4 and T5 (p < 0.001), and in mean UD-BMD between T3 and T4 (p = 0.016). Considering menarche, there was an important increment in bone mass up to 3 years after menarche, and it was significant until 2 years after for D-BMD (p < 0.02) and 1 year after for UD-BMD (p < 0.001). In girls and boys, bone mass increments did not correlate with height increments. A delay in bone mass increments was observed at early Tanner stages. CONCLUSION: Between 4 and 8 years in girls and 4 and 12 years in boys, there is a slow increment in bone density correlated with age and sex. A steeper slope in bone growth started with puberty, correlated with Tanner stage. Bone mineral increments did not correlate with height increments. At the end of pubertal development bone acquisition slowed down. Men achieved higher bone density values than women.

Absorptiometry, Photon↗
PubMed1998

Blue filter amblyopia treatment protocol for strabismic amblyopia: a prospective comparative study of 50 cases.

PURPOSE: Previous studies of monochromatic visual evoked potentials confirm the strong suppression of (the cortical representation of) paracentral retinal areas of functionally amblyopic eyes, by a flat response to a blue stimulus. A clinical trial stimulating these areas with blue light was encouraging, and justified a prospective comparison of this treatment with conventional classic treatment. SUBJECTS AND METHODS: In 50 strabismic children with amblyopia, the blue filter treatment protocol (flash stimulation with, and the wearing of, a blue filter during occlusion of the better eye for one hour daily) was compared with the classical treatment (full time total occlusion by patch) in a prospective matched and randomized study. Patients 3 to 7 years old without previous treatment and a visual acuity up to 0.3 were admitted to the study. Visual acuity and fixation behavior were used as the parameters of comparison. Visual Evoked Potentials by monochromatic flashes were also studied. Results of treatment were compared after 6 months. RESULTS: The visual acuity outcome for the blue filter treatment was "statistically significantly" better (p=0.005). The greatest improvement was seen in the subgroup of children with eccentric fixation (p=0.01). Fixation behavior also showed a better outcome from the blue filter treatment (p=0.05) favoring especially children between 3 and 5 years. In children of this age with a visual acuity better than 0.1 we found a very "statistically significant" difference between the two treatments (p=0.004). In children 3 to 5 years old with poorer visual acuity we also found a "statistically significant" difference in the two treatments (p=0.04). The interocular difference of amplitude on the Visual Evoked Potentials also demonstrated more improvement in children treated with the blue filter. This treatment improved especially the cortical response to blue flash stimulation, correlating to paracentral retinal areas. CONCLUSIONS: The blue filter treatment protocol provided better results for treating amblyopia than the conventional classic occlusion treatment method. We propose that stimulation of these paracentral retinal areas triggers a better disinhibition of a functionally amblyopic eye.

Amblyopia↗
PubMed1998

[Malignant melanoma in children. Apropos of 6 cases].

Six cases of malignant melanoma were observed in children aged 5-14 years, over a 14-year period: both sexes were equally affected. In three cases, the melanoma was a primary tumor, which indicates that this diagnosis should always be born in mind in children and any suspicious lesion should be biopsied and removed. Three cases had a family history: dysplastic naevus in two cases and malignant melanoma in one case, which confirms the increased risk in some families. Histologically, nodular forms were more frequent than those which spread superficially and the tumors were quite thick when diagnosed (mean thickness: 3.9 mm). Treatment includes wide excision and coverage with skin grafts associated with immuno or chemotherapy in some cases. Mean follow-up was 38 months and no death occurred during this period.

Adolescent↗
PubMed1998

[What's new in upper limb skin expansion?].

The indications for skin expansion of the upper limb are now well defined. Based on a series of 56 cases, the authors confirm that a rigorous technique and good management of complications can minimize failures of the method. Technical progress and new biomaterials certainly allow further reduction of these complications and possibly the development of new indications.

Adolescent↗
PubMed1997

[Surgical treatment of gynecomastia].

Surgical treatment of gynaecomastia is easy. When medical treatment is insufficient, surgery can improve the deformations with a minimal scarring. After morphological aspects and surgical objects description, the authors explain surgical techniques and indications.

Adolescent↗
PubMed1997

[Plantar verrucous carcinoma. A case report and literature review].

The authors report a case of carcinoma cuniculatum plantar and review the literature on this rare tumour. The clinical features and course of this tumour. The clinical features and course of this tumour are successively described. Although associated with limited malignancy and almost exclusively local extension, progression of this disease may lead to amputation, which can be avoided by early diagnosis, especially based on precise histological examination of all tumours with a benign recurrent appearance after well conducted treatment.

Carcinoma, Verrucous↗