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Biomedical subjects

J Medina

Publications and source records attributed to J Medina.

At least 37 records · Page 2Linked to original sources
PubMed2001

Use of ultrasound to prepare lipid emulsions of lorazepam for intravenous injection.

Lipid emulsions can be used as a vehicle for the production of low-volume injectable preparations with minimally water-soluble active ingredients. First, we focus on the galenic and technological conditions established by ultrasound techniques. A 2(5) factorial design was used to optimize the carrier emulsion. The study then deals with the development of a parenteral emulsion formulation for lorazepam (1 mg/ml), which is compared with the highest concentration (0.05 mg/ml) achieved in the optimal aqueous diluent for lorazepam (dextrose 5% in water). The physical and chemical stability of lorazepam in the emulsion was examined for 7 months.

Analysis of Variance↗
PubMed2001

Ductular morphogenesis and functional polarization of normal human biliary epithelial cells in three-dimensional culture.

BACKGROUND/AIMS: The understanding of the physiology and function of human biliary epithelial cells (hBEC) has been improved by studies in monolayer culture systems. The aim was to develop a polarized model to elucidate the mechanisms of ductular morphogenesis and functional differentiation of hBEC. METHODS: The morphological, phenotypic and functional properties of hBEC cultured as three-dimensional aggregates in collagen gel were assessed in medium supplemented with (or without) human hepatocyte growth factor (hHGF) and foetal bovine serum. RESULTS: In the absence of added mitogens and serum, cells maintained as morphologically polarized aggregates, organized around a central lumen, were positive for phenotypic markers of biliary epithelium and negative for markers of other cell types. Functional markers, gamma-glutamyl-transferase, anion exchanger-2, responses to gamma interferon and forskolin induced secretion, were preserved. hHGF increased both the size and number of aggregates and induced hBEC to invade the gel and lumena forming anastomosing networks of cells. CONCLUSIONS: Collagen gel culture in the absence of added growth factors and serum provides a model for analysis of the polarized functions of hBEC. The formation of poorly organized cords of cells in response to hHGF suggests that collagen gel culture may provide a model for the investigation of atypical ductular morphogenesis of the human biliary tract.

Adult↗
PubMed2001

[Recurrence of finger tendon giant cell tumors after excision through a "shark teeth" approach. Report of 25 cases].

Local recurrences after excision of a giant cell tumor of the tendon sheath are classically related to incomplete excision. We have review a special group of circumferential tumors excised through a huge approach. Twenty-six circumferential tumors were excised between 1985 and 1998, through a special incision described by the senior author. It is composed of four triangular flaps drawn around the finger, one dorsal, one palmar (both proximally based) and two lateral (distally based). Six presented already with a recurrence of previous operations (mean 2.5 interventions). Some anatomical neighboring structure was "invaded" in all except one case. However the approach allows for a macroscopically satisfactory excision. Twenty-five patients were reviewed by an independent observator after a mean follow-up of six years. Six patients (24%) presented a recurrence after a mean postoperative delay of 17 months. Among them five have been already operated (83%) and five had multiple tumors. Satisfactory excision does not prevent recurrence and two types of distinct tumors exist. Recent immunohistological studies give support to this view and such examination is recommended.

Adult↗
PubMed2001

[Percutaneous needle aponeurotomy. Complications and results].

Recently French rheumatologists have repopularized fasciotomy using a percutaneous needle technique. This blind approach has been claimed to be plagued by numerous complications. We reviewed the charts of 211 patients treated consecutively on 261 hands and 311 fingers to assess the rate of postoperative complications. The first 100 patients were evaluated with a mean follow up of 3.2 years to assess the rate of recurrences and extension of the disease. In the whole group the mean age was 65 years and delay between onset and treatment was six years. Rupture of the cords were performed only in the palm in 165 cases, in the palm and finger in 111 and purely at digital level in 35. Complications were scarce without infection or tendon injury but one digital nerve was found injured during the second procedure. Postoperative gain was prominent at metacarpophalangeal joint level (79% versus 65% at interphalangeal level). Reoperation rate was 24%. In the group controlled at 3.2 years follow up, recurrence rate was 58% and disease "activity" 69%. Fifty nine hands need further surgery. The ideal indication for this simple and reliable technique is an elderly patient with a bowing cord and a predominant MP contracture.

Adult↗
PubMed2001

Immunopathogenesis of cholestatic autoimmune liver diseases.

Primary biliary cirrhosis and primary sclerosing cholangitis are well recognized chronic cholestatic liver diseases that are considered to have an autoimmune basis. Recent progress in the study of autoimmune liver diseases has improved the recognition and characterization of these conditions. An important component of this progress has been the identification of liver disease-associated autoantibodies and their respective target antigens, and the development of specific assays for these autoantibodies. In addition, some nonhumoral immunological findings imply an involvement of specific immunopathogenic mechanisms in the development of these conditions. Furthermore, immunogenetic factors associated with increased susceptibility to some of these diseases have been identified. This article reviews the most relevant information relating to the postulated autoimmune pathogenesis of these diseases, with special emphasis on their associated humoral and cellular immunological abnormalities and immunopathogenetic factors. Some of the remaining important unresolved issues relating to the pathogenesis of these diseases, that need to be addressed in further research, are highlighted.

Autoimmune Diseases↗
PubMed2001

A congenital hand deformity: Dupuytren's disease.

A 10-month-old child presented with a lack of extension at the distal interphalangeal joint. Despite the absence of trauma, a provisional diagnosis of mallet finger led to treatment using a short dorsal splint. Four months later the flexion had increased and included the proximal interphalangeal joint. Palpation revealed a palmar cord on the lateral aspect of the finger. Surgery disclosed a typical Dupuytren cord and the histology supported this diagnosis. There was no known family history of the disease. There was no sign of recurrence 27 months after surgery in this case of Dupuytren's disease that was present at birth.

Dupuytren Contracture↗
PubMed2001

Toe transfer in congenital hand malformations.

Fifty-eight patients with congenital hand abnormalities underwent 65 toe-to-hand transfers. Symbrachydactyly (51 cases) was the most frequent indication. Forty-seven second toe-to-hand transfers were performed in 44 patients. The mean follow-up time was 5.2 years. Two failures occurred in cases in which only one artery was anastomosed; no failures were noted when more than one artery fed the transfer. Two patients with a single second-toe transfer presented with lateral instability of the transferred metatarsophalangeal joint. The mean active range of motion was 38 degrees, with a mean extension lag of 25 degrees. The mean two-point discrimination was 5 mm. Forty-one patients used the transferred toe well, when performing activities of daily living and playing games. Toe-to-hand transfer, prior to the establishment of the grip pattern, facilitates integration of the transfer.

Child, Preschool↗
PubMed2001

Microsurgical reconstruction of the hypoplastic thumb, type IIIB.

If a classically hypoplastic thumb, type IIIA, presenting with a first carpometacarpal joint, is amenable to reconstruction, a type IIIB case without the basal joint, is classically treated by pollicization. The authors concur with this opinion, but found two circumstances in which reconstruction is an option in a type IIIB thumb, either when an adolescent asks for improvement of an unstable but utilized thumb, or when a parent definitely refuses pollicization. In such cases, a free, vascularized metatarsophalangeal joint is the first step of the reconstruction, followed by classic non-microsurgical steps. The authors reviewed five cases, with a mean follow-up of 7.8 years. Hypoplasia of the reconstructed thumb, and a limited pinch, allow this option only with restricted indications.

Hand Deformities, Congenital↗
PubMed2001

Assessment of the phototoxic potential of compounds and finished topical products using a human reconstructed epidermis.

The goal of this study was to design a model system for the assessment of phototoxic potential using a human reconstructed epidermis (HRE, SkinEthic Laboratories, Nice, France), by testing some representative phototoxic (P) and non-phototoxic (NP) compounds and finished topical products. The tissue response to 24-h application of 5-5000 microg/mL of the test agents in the presence and absence of UVA light was analyzed in terms of viability (Lactate Dehydrogenase release), pro-inflammatory activity (IL-8 release and mRNA expression) and morphology (histopathology). 8-Methoxypsoralen (P) and promethazin (P), but not sodium lauryl sulfate (NP) produced cytotoxicity concentration-response curves significantly different between irradiated and nonirradiated tissues. Only irradiated tissues showed morphological damage. Application of tetracyclin (P) in the culture medium, but not topically, induced similar signs of phototoxicity. 6-Methylcoumarine (weak P) was not cytotoxic, yet it increased IL-8 release and mRNA expression only following UVA irradiation. PUVA therapy creams containing 1% 8-Methoxy-psoralen (P) or coal tar (P) decreased viability and induced histologic damage in UVA-exposed tissues. In conclusion, the phototoxic potential of the tested agents was correctly predicted by using a tiered strategy that involves determining cytotoxicity, production of IL-8, and morphological damage following exposure of the HRE to the compounds and UVA light.

Cell Survival↗
PubMed2001

Correction of first web space deficiency in congenital deformities of the hand with the pseudokite flap.

The authors describe a new flap to enlarge or create a first web in patients with congenital deficiencies of the hand. This lozenge-shaped flap is harvested from the dorsoradial aspect of the index finger based on a narrow proximal skin bridge protecting its axial vascularization. A dorsal skin graft of the donor site is avoided by closure using a rhomboid flap. Procedures in 16 patients were performed and reviewed; the only complication was insertion of a small split-thickness graft in five patients to avoid tension at the metacarpophalangeal joint level. The flap lengthened the web fold an average of 3.2 cm without "pseudolengthening" the thumb.

Child↗
PubMed2001

Metacarpal synostosis: a simple classification and a new treatment technique.

The current classification of metacarpal synostosis is based on the extent of the synostosis. The authors propose a new classification that takes into account the shape of the metacarpal bones, the curvature of the epiphysis, and the discrepancy in length between the two bones. This classification provides better guidelines for the correction of all components of the deformity. The classification is based on the authors' observations of and experience with 36 cases of metacarpal synostosis; 13 of the deformities were surgically corrected. The I-shaped deformity, whether with distinct (type d) or fused (type f) metacarpophalangeal joints, does not require surgical correction. The U-shaped deformity has parallel epiphysis and does not require surgery unless the two metacarpals are asymmetrical in length (type a) or tightly fused (type t); in these cases, simple lengthening or widening of the space with a bone graft is sufficient. Y-shaped synostosis should be separated whether the branches are symmetrical or asymmetrical, the latter having one branch shorter than the other. Because the epiphyses are already divergent, simple separation does not effectively correct Y-shaped synostosis. The authors propose an osteotomy to isolate a trapezoidal segment of bone from the bifurcation. The isolated bone segment is then reversed in the proximal-distal direction to provide a "plateau" upon which the two distal metacarpals can be realigned. Two cases of Ys (symmetrical) synostosis were successfully treated with this technique; one case of Ya (asymmetrical) synostosis also required distraction lengthening of the shorter metacarpal to achieve an excellent result. One of the most difficult types of metacarpal synostosis to treat is k-shaped synostosis, observed only between the fourth and fifth metacarpals; in this type, the head of the short fifth metacarpal abuts the metaphysis of the fourth. Osteotomy and distraction lengthening provide predictable results for correction of this deformity. The authors suggest that k-shaped synostosis might represent a late evolution of untreated Ua synostosis.

Child, Preschool↗
PubMed2001

Developmental and stress regulation of RCI2A and RCI2B, two cold-inducible genes of arabidopsis encoding highly conserved hydrophobic proteins.

The capability of most higher plants to tolerate environmental conditions strongly depends on their developmental stage. In addition, environmental factors have pleiotropic effects on many developmental processes. The interaction between plant development and environmental conditions implies that some genes must be regulated by both environmental factors and developmental cues. To understand their developmental regulation and obtain possible clues on their functions, we have isolated genomic clones for RCI2A and RCI2B, two genes from Arabidopsis ecotype Columbia (Col), whose expression is induced in response to low temperature, dehydration, salt stress, and abscisic acid. The promoters of RCI2A and RCI2B were fused to the uidA (GUS)-coding sequence and the resulting constructs used to transform Arabidopsis. GUS activity was analyzed in transgenic plants during development under both stressed and unstressed conditions. Transgenic plants with either the RCI2A or RCI2B promoter showed strong GUS expression during the first stages of seed development and germination, in vascular bundles, pollen, and most interestingly in guard cells. When transgenic plants were exposed to low temperature, dehydration, salt stress, or abscisic acid, reporter gene expression was induced in most tissues. These results indicate that RCI2A and RCI2B are regulated at transcriptional level during plant development and in response to different environmental stimuli and treatments. The potential role of RCI2A and RCI2B in plant development and stress response is discussed.

Abscisic Acid↗
PubMed2001

The role of hydrogen peroxide in the contractile response to angiotensin II.

In the last years, reactive oxygen species (ROS) have been proposed as mediators of proliferative/hypertrophic responses to angiotensin II (Ang II), both in vivo and in vitro. However, the hypothesis that the Ang II-dependent cell contraction could be mediated by ROS, particularly H2O2, has not been tested. Present experiments were devoted to test this hypothesis and to analyze the possible mechanisms involved. Catalase (CAT) prevented the increased myosin light chain phosphorylation and the decreased planar cell surface area (PCSA) induced by 1 microM Ang II in cultured rat vascular smooth muscle cells (VSMC). This preventive effect of CAT was also detected when 1 microM platelet-activating factor (PAF) was used as a contractile agonist instead of Ang II. Similar results were found when using horseradish peroxidase as an H2O2 scavenger or cultured rat mesangial cells. In vascular smooth muscle cells, CAT modified neither the binding of labeled Ang II nor the Ang II-induced inositol 1,4,5-trisphosphate (IP3) synthesis. However, it completely abolished the Ang II-dependent calcium peak, in a dose-dependent fashion. CAT-loaded cells (increased intracellular CAT concentration over 3-fold) did not show either a decreased PCSA or an increased intracellular calcium concentration after Ang II treatment. Ang II stimulated the H2O2 synthesis by cultured cells, and the presence of CAT in the extracellular compartment significantly diminished the Ang II-dependent increased intracellular H2O2 concentration. The physiological importance of these findings was tested in rat thoracic aortic rings: CAT prevented the contraction elicited by Ang II. In summary, present experiments point to H2O2 as a critical intracellular metabolite in the regulation of cell contraction.

Angiotensin II↗