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Biomedical subjects

E Lopez

Publications and source records attributed to E Lopez.

At least 73 records · Page 4Linked to original sources
PubMed1993

A multidisciplinary approach to the early detection of ovarian carcinoma: rationale, protocol design, and early results.

OBJECTIVE: This study was undertaken to determine the feasibility of currently available tests to detect ovarian cancer at a curable stage. By studying women at risk for the disease on the basis of their family histories of cancer, we hope to gain insight into the genetics and biologic characteristics of ovarian cancer. STUDY DESIGN: Asymptomatic women with a family history of cancer are interviewed by geneticists to obtain accurate pedigree and epidemiologic data. Screening tests including transvaginal ultrasonography, color Doppler imaging, CA 125 measurement, and other investigative biomarkers are performed between cycle days 3 and 8 and repeated biannually. RESULTS: A total of 597 women without symptoms were screened between July 1991 and June 1992. Cystic or complex adnexal masses were detected in 6.2% of patients. A pulsatile index value < 1.0 was measured in 80% of premenopausal patients and 24% of postmenopausal patients, whereas a resistance index value < 0.4 occurred in 12% of premenopausal and 3% of postmenopausal patients. A CA 125 level > 35 U/ml was found in 11.4% of the study participants. To date, one stage IA borderline ovarian tumor and one endometrial carcinoma have been found. CONCLUSIONS: Ovarian cancer screening needs to be investigated in a controlled fashion to determine means that will ultimately improve the survival from the disease.

Adult↗
PubMed1993

Assessment of the efficacy and safety of nimesulide vs naproxen in paediatric patients with respiratory tract infections. A comparative single-blind study.

A total of 99 paediatric patients (57 male, 42 female) aged 1 to 12 years, weighing 10 to 40kg and with acute pharyngo-amygdalitis were enrolled in a single-blind study to assess the efficacy and tolerability of nimesulide in comparison with naproxen when both drugs were administered over an 8-day treatment period. Among the 2 treatment groups comprising 99 evaluable patients, demographic analysis of age, weight and height did not reveal statistically significant differences. Evaluation of fever, pain, inflammation and nasal obstruction over the 8-day treatment period showed a significant improvement in these parameters for those patients treated with nimesulide when compared with naproxen from day 1, with remission of symptoms starting from day 3. These findings were complemented by a superior tolerability profile reported for nimesulide-treated patients. In conclusion, nimesulide appears to be a safe and effective treatment for paediatric patients with pharyngo-amygdalitis and it has shown superior efficacy and tolerability when compared with naproxen.

Acute Disease↗
PubMed1993

[Proteus syndrome].

We report the case of a 4-year old boy presenting with a polymalformative syndrome made of cutaneous and subcutaneous lesions associated with visceral and skeletal lesions. The cutaneous lesions consisted of 3 verrucous hamartomas, one haemangioma and one lymphangioma. The subcutaneous lesions were melting of panniculus adiposus, plantar tumefaction and diffuse lipomatosis of the peritoneal and retroperitoneal cavities. The skeletal lesions were uneven lower limbs and dorsal scoliosis. Atrophy of the intestinal villi was also found. The diagnosis of Proteus syndrome was made.

Child, Preschool↗
PubMed1993

Europium(III) trisbipyridine cryptate label for time-resolved fluorescence detection of polymerase chain reaction products fixed on a solid support.

We report a method for the nonradioactive detection of specific amplified target DNA, based on a new long-lived fluorescent label, europium(III) trisbipyridine cryptate [TBP-(Eu3+)]. After a polymerase chain reaction with a set of nested primers, microtiter affinity-collected hybrids were recognized by a TBP(Eu3+)-labeled antibody. The particular structure of the label containing the energy transfer units (bipyridine moieties) enables direct fluorescence measurement on the solid phase. Moreover, its stability and long lifetime contribute to the enhancement of the signal-to-noise ratio. The usefulness of this new label is illustrated by the detection of human papillomavirus type 16 DNA in clinical smears.

2,4-Dinitrophenol↗
PubMed1992

Nacre initiates biomineralization by human osteoblasts maintained in vitro.

When nacreous shell produced by the marine oyster Pinctada maxima, used as a biomaterial in oral surgery, is implanted in human bone, new bone formation occurs, resulting in a tight welding of the bone to the nacre [16]. These findings are consistent with the possibility that nacre adjacent to bone can locally stimulate osteogenic activity. To test this hypothesis, we have evaluated the effect of the simultaneous presence of bone and nacre on human osteoblasts in vitro. Nacre chips (1 mm3) were placed at approximately 1 mm distance from a similarly sized bone chip on a layer of first passage human osteoblasts. None of the chemical inducers generally required to obtain bone mineralization in vitro (in particular, beta-glycerophosphate) was added to the cultures. Mineralized sections of the cultures were evaluated by light and electron microscopy, contact microradiography, and Laser Raman Spectroscopy. The results demonstrated that nacre has strong osteogenic effects on human osteoblasts when placed in proximity to bone in vitro. New bone formation occurred by both appositional growth on the existing bone and by the formation of mineralized nodules within the matrix adjacent to the bone explant. Electron microscopic evaluation of these sites demonstrated findings typical of those described in the course of bone formation in vivo, and no evidence of toxicity was observed. In addition, under the conditions of culture used, nacre can also promote the formation by osteoblasts of a structure with characteristics similar to nacre (e.g., lamellar organic matrix mineralized with aragonite, as demonstrated by Laser Raman Spectroscopy).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Demonstration of the capacity of nacre to induce bone formation by human osteoblasts maintained in vitro.

Nacre implanted in vivo in bone is osteogenic suggesting that it may possess factor(s) which stimulate bone formation. The present study was undertaken to test the hypothesis that nacre can induce mineralization by human osteoblasts in vitro. Nacre chips were placed on a layer of first passage human osteoblasts. None of the chemical inducers generally required to obtain bone formation in vitro was added to the cultures. Osteoblasts proliferated and were clearly attracted by nacre chips to which they attached. Induction of mineralization appeared preferentially in bundles of osteoblasts surrounding the nacre chips. Three-dimensional nodules were formed by a dense osteoid matrix with cuboidal osteoblasts at the periphery and osteocytic-like cells in the center. These nodules contained foci with features of mineralized structures and bone-like structures, both radiodense to X-ray. Active osteoblasts (e.m.) with abundant rough endoplasmic reticulum, extrusion of collagen fibrils and budding of vesicles were observed. Matrix vesicles induced mineral deposition. Extracellular collagen fibrils appeared cross-banded and electrodense indicating mineralization. These results demonstrate that a complete sequence of bone formation is reproduced when human osteoblasts are cultured in the presence of nacre. This model provides a new approach to study the steps of osteoblastic differentiation and the mechanisms of induction of mineralization.

Animals↗
PubMed1991

Europium(III) cryptate: a fluorescent label for the detection of DNA hybrids on solid support.

We report here a new detection method for DNA hybrids on dot blots. The process utilizes DNA or oligonucleotide probes labeled with biotin, followed by recognition with a conjugate of streptavidin and europium cryptate, a time-resolved fluorescent label. Unlike the other lanthanide chelates, this label is an organic molecule embedding a europium ion into an intramolecular cavity. This structure has a better stability in diluted assay media, a good sensitivity even on solid support, and an elevated fluorescence lifetime which allows elimination of most of the background generated by other species present in the assay medium. This procedure is quantitative and detects down to 2 amol of a model DNA, which is similar to other nonisotopic (especially colorimetric) methods. The main advantages of this method are easy automation, quantitation, and rapidity of measurements.

Bacterial Proteins↗
PubMed1990

Giant liposomes: a model system in which to obtain patch-clamp recordings of ionic channels.

Cell-size, giant liposomes have been formed by submitting a mixture of asolectin lipid vesicles and native membranes from Torpedo, highly enriched in acetylcholine receptor (AcChR), to a partial dehydration/rehydration cycle [Criado, M., & Keller, B. U. (1987) FEBS Lett. 224, 172-176]. Giant liposomes can be prepared in bulk quantities, in the absence of potentially damaging detergents or organic solvents, and their formation is mediated by membrane fusion phenomena. In fact, fluorescence microscopy and freeze-fracture data indicate that protein and lipid components of the initial membranes and lipid vesicles are homogenously distributed in the resulting liposomes. Giant liposomes containing AcChR have been used as a model to evaluate whether this system can be used to monitor the activity of ionic channels by using high-resolution, patch-clamp techniques. Excised liposome patches in an "inside-out" configuration have been used in this work. We find that the most frequent pattern of electrical activity in response to the presence of acetylcholine in the patch pipet corresponds to a cation-specific channel exhibiting a dominant conductance level and a sublevel of approximately 78 and 25 pS, respectively. Such channel activity exhibits the pharmacological specificity, ion channel activation, ion selectivity, and desensitization properties expected from native Torpedo AcChR. Thus, it appears that the giant liposome technique offers a distinct advantage over other reconstitution procedures in that it provides a unique opportunity to undertake simultaneous biochemical, morphological, and electrophysiological studies of the incorporated ionic channel proteins.

Animals↗
PubMed1990

Artificial dental root made of natural calcium carbonate (Bioracine).

'Bioracine' is an artificial dental root made of natural calcium carbonate (Pinctade maxima mother of pearl). This non-biodegradable material is very close to bone tissue in its physicochemical composition and presents remarkable hardness, resistance and elasticity. Bioracine is a buried dental implant with a special screw thread, presenting a large surface which shows pores of 2-3 mum. A histological study of the interface between the implant and human maxillary bone demonstrated an extraordinary cellular union between these two tissues. Furthermore, bioracine presents two new technical innovations: a periprosthetic epithelial attachment of connective tissue with an active shock absorbing system. Bioracine is an exceptional dental root substitute that matches the biological properties of natural bone.

Adult↗
PubMed1990

[Hormonal stimulation, in vivo, of the ovary of European eel in the yellow stage].

The immature ovary of yellow eel was stimulated by a long-term treatment with a gonadotropin II rich extract of carp pituitary. Ovarian follicles of treated yellow eels showed an accumulation of lipidic vacuoles in the oocyte cytoplasm and a thickened follicular envelope (in this regard, they resembled the ovarian follicles of previously studied silver eels). The treatment also resulted in a significant but limited increase in the gonadosomatic ratio and mean follicle size (these values were much lower than those measured in silver eels). No change in pigmentation or general morphology was observed. Thus, under our experimental conditions, a gonadotropic stimulation of the yellow eel leads to some but not the totality of the ovarian modifications which occur physiologically during silvering.

Anguilla↗
PubMed1989

Partial purification of parathyrin from the corpuscles of Stannius (PCS) of the eel (Anguilla anguilla, L.).

It has been previously shown that the eel corpuscles of Stannius (CS) synthesize and secrete a substance (PCS) which is functionally and immunologically related to the mammalian parathyrin family. Purification of PCS, including anion-exchange chromatography, ODS C-18 reverse-phase HPLC, and affinity chromatography, showed that a biologically active peak, eluted in 32% acetonitrile, contains a 32- to 34-kDa protein which is 600-fold more potent than the crude extract is a test involving the hypocalcemic response in the CS-deprived eel. Specific immunoprecipitation of protein encoded by mRNA extracted from eel CS indicates that a 45-kDa precursor is involved in PCS synthesis. The hypothetical significance of a "large" parathyrin-like molecule in fish is suggested in relation to what is known about mammalian parathyrin gene expression.

Alkaline Phosphatase↗
PubMed1989

[Soldering without transition (osteoassimilation) between the human maxillary bone and a compact dental implant in natural calcite from marine invertebrate].

We present evidence for the formation of woven bone between human maxillary lamellar bone (the target site) and a coral implant (Corallium johnsoni Gray). This newly formed bone is characterized by numerous osteocytes located in spherical lacunae and having many ramified processes directed towards the coral; some of these processes continue into the implant surface. Healthy osteocytes were detected within the superficial part of the coral, next to the newly formed bone. Neither osteoclast nor surface of resorption has been noticed. All these observations indicate tight welding or osteoassimilation without any transition between the maxillary bone and the graft. We have obtained analogous results by using grafts of molluscan mother-of-pearl. Our results differ from those reported by other authors, probably due to the compactness of the biomaterial used here.

Animals↗
PubMed1988

Stimulation of gonadotropin release and of ovarian development, by the administration of a gonadoliberin agonist and of dopamine antagonists, in female silver eel pretreated with estradiol.

In freshwater or seawater female silver eel, the release of gonadotropin (GTH) accumulated in the pituitary under estradiol (E2) influence could be stimulated by a conjugated treatment with a mammalian gonadoliberin agonist (GnRH-A = des-Gly10, (D-Ala6)-LH-RH ethylamide) and a blocker of dopamine receptor (pimozide). Furthermore, despite the GTH release, no reduction or even a significant increase in pituitary GTH levels were noted, indicating a stimulation of GTH synthesis. In consequence of the endogenous GTH release, a stimulation of ovarian development was induced, as demonstrated by the gonadosomatic index and histological study. Similar results were obtained with a combined treatment with GnRH-A and an inhibitor of catecholamine synthesis (L-alpha-methyl-3,4-dihydroxyphenylalanine). In contrast, no effect was produced by GnRH-A, pimozide, or L-alpha-methyl-DOPA, given alone. The results suggest that a double neuroendocrine mechanism (a lack of GnRH production and a dopaminergic inhibition of GnRH action) is involved in the prepubertal blockage of eel gonadotropic function before the reproductive migration.

Anguilla↗
PubMed1988

Calcium-dependent metabolism of 25-hydroxycholecalciferol in silver eel tissues.

We investigated the in vitro metabolism of [26,27-3H]-25-(OH)D3 in different eel tissues. After incubation with [3H]-25-(OH)D3, tissues were extracted with methanol-chloroform and chromatographed on Sephadex LH 20 columns. Two derivatives less polar than 25-(OH)D3 were detected, the first one being sensitive to KOH treatment. Three peaks more polar than 25-(OH)D3 were also found: peak I migrated close to the 24,25-(OH)2D3 area and was quantitatively the most important, but the presence of 24,25-(OH)2D3 could not be demonstrated; peak II migrated in the 1,25-(OH)2D3 region; and peak III had an elution position twice that of peak II. After 6-h incubation of tissues isolated from control eels, peak I was found in all tissues including intestine and gills. It was highest in pituitary gland and brain and lowest in ovaries and muscle. It was not significantly modified 20 days after ablation of the corpuscules of Stannius. In contrast, in vivo daily calcium chloride injection was followed 24 hr later by a significant increase in the [3H]-25-(OH)D3 conversion into peak I in gills, intestine, and the spinal cord and by an inhibition of this conversion in pituitary gland, skin, and muscle. The inhibition was found in all tissues after five daily calcium injections. Calcium injection had no effect on the in vitro metabolite synthesis by the corpuscules of Stannius. These results suggest that vitamin D is not metabolized in the same way in eel as in mammals and that this metabolism could in part be calcium dependent.

Animals↗