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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 271 records · Page 15Linked to original sources
PubMed1997

[Cholangiocarcinoma arising from biliary micro-hamartomas in a man suffering from hemochromatosis].

A case of cholangiocarcinoma arising from multiple bile duct hamartomas (von Meyenburg complexes) is reported in a 68-year-old man. This man has been treated for genetic hemochromatosis for 2 years. The diagnosis of cholangiocarcinoma was suspected by a systematic ultrasound test and made through the pathological examination of the resected specimen. Only six cases have already been reported. Our case is peculiar because it occurred on a genetic hemochromatosis.

Aged↗
PubMed1997

[Amyloid goiter. Report of two cases].

We report two cases of amyloid goiter which clinical appearance had evoked a neoplastic lesion. The diagnosis was made by histologic examination. The nature of the amyloid precursor, determined by immunohistochemistry, has allowed to evoke primitive amyloidosis in one case and to attribute amyloid goiter to renal insufficiency in the second case.

Aged↗
PubMed1996

A sensitive and rapid fluorescence-based assay for determination of tetanus toxin peptidase activity.

The light chain of tetanus toxin (TeNT-L chain), endowed with a zinc metalloendopeptidase activity, cleaves specifically the vesicle-associated membrane protein (VAMP), also called synaptobrevin, at a single peptide bond (Gln76-Phe77), resulting in the blockade of neuroexocytosis. The 50-mer synaptobrevin peptide S 39-88, synthesized by solid-phase peptide synthesis, was determined to be the minimum substrate of TeNT still notably hydrolyzed by TeNT-L chain. In this peptide, Tyr88 was substituted by the highly fluorescent amino acid (L) pyrenylalanine (Pya) which was synthesized in good yields by an enantioselective method. The fluorescent substrate [Pya88] S 39-88 was cleaved four times more rapidly by TeNT-L chain than S 39-88 (kcat/Km = 9635 and 2455 M-1.min-1, respectively). One of the two metabolites formed by the action of TeNT L chain, [Pya88] S 77-88, was easily separated from the substrate in one step using Sep-Pak Vac C18 cartridges and its concentration quantified by fluorescence. This novel enzymatic assay, which could be easily extended to other clostridial neurotoxins, is a major improvement in term of sensitivity and time saving, compared to currently used methods (SDS-PAGE, HPLC). It lends itself readily to automation for large-scale screening of selective and potent inhibitors of these neurotoxins which remain to be developed.

Amino Acid Sequence↗
PubMed1996

Genomic structure and chromosomal localization of the mouse CDEI-binding protein CDEBP (APLP2) gene and promoter sequences.

The genomic structure of the mouse gene encoding the CDEBP protein has been established. The protein was initially identified on the basis of its ability to bind the CDEI motif (GTCACATG). The same locus has been independently described under the name APLP2, on the basis of sequence similarities with the Amyloid Precursor Protein (APP). The exon-intron distribution of Cdebp appears strikingly similar to that of the App gene in the regions encoding the conserved domains, with a divergent structure in the other parts. The transcription start site has been localized, and sequences with promoter activity have been identified immediately upstream of it by their ability to direct the expression of a reporter luciferase gene in transfected cells. This region is devoid of either TATA or CAAT boxes. The gene has been mapped to mouse chromosome 9 by in situ hybridization on metaphase chromosomes.

Animals↗
PubMed1996

The use of duplex ultrasonography in penetrating neck trauma.

OBJECTIVE: To compare intraoperative findings and/or angiography with color-flow duplex scan. DESIGN: This prospective double-blind study was performed on all stable patients with zone 1, 2, or 3 penetrating neck trauma. Results of angiographic or intraoperative findings were compared with the results of duplex ultrasonographic scans. MAIN OUTCOME MEASURES: Fifty-five patients were studied over a 2-year period in which the distribution of injuries included 23 stab wounds (42%), 30 gunshot wounds (54%), and 2 motor vehicular lacerations (4%). There were 42 patients (76%) with normal ultrasonographic results and 13 patients (24%) with abnormal ultrasonographic results. The true-negative rate was 100%; however, there were 2 false positives resulting in 100% sensitivity and 85% specificity. CONCLUSIONS: Duplex ultrasonography provides an excellent diagnostic modality with cost-saving, patient-friendly characteristics and a low rate of morbidity. It should be instituted as the primary diagnostic procedure of choice for penetrating neck trauma.

Double-Blind Method↗
PubMed1996

In vivo characterization of a fluoropassivated gelatin-impregnated polyester mesh for hernia repair.

The present study was undertaken to evaluate a new prototype mesh that consists of a knitted polyester structure treated with a fluoropolymer and impregnated with gelatin. The Fluoropassiv mesh, as well as two controls, the Surgipro polypropylene mesh and the Gore-Tex expanded polytetrafluoroethylene patch, were used for the repair of experimentally induced abdominal hernias in piglets and followed for scheduled implantation periods of 4, 15, and 60 days. At the sacrifice the mesh and surrounding tissue were excised for histological assessment of the healing sequence, for the identification of changes in hematologic and immunological characteristics, and for the measurement of the mechanical properties. After cleaning to remove the encroaching tissue, the explanted devices were monitored for biostability by infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The present study has demonstrated that the Fluoropassiv mesh provides adequate mechanical strength and compares favorably with the two controls. No exacerbated systemic or in situ hematologic or immunological reactions were observed with either the meshes of the patch material. Histological studies revealed that thick collagenous and vascularized tissue were well anchored to the three biomaterials as early as 15 days after implantation. The degree of tissue penetration differed depending on the device. Chemically, they proved stable over time.

Abdominal Muscles↗
PubMed1996

Monocyte chemoattractant protein-1: receptor interactions and calcium signaling mechanisms.

Monocyte chemoattractant protein-1 (MCP-1) is a member of the Cys-Cys chemokine family. Two related MCP-1 receptors have been identified (CC-CKR2A and CC-CKR2B), although the precise kinetics of ligand binding and calcium signaling of these receptors has yet to be investigated. To examine this more closely, the human MCP-1 receptors were cloned and expressed in Chinese hamster ovary (CHO) cells. Membranes prepared from cells expressing CC-CKR2B bind MCP-1 selectively and with high affinity (Kd = 120 pM). MCP-1 stimulation of recombinant CHO cells expressing CC-CKR2B induces a rapid increase in intracellular Ca2+ through both receptor-operated Ca2+ channels and mobilization of Ca2+ from intracellular stores, and leads to a rapid temperature-dependent internalization of the ligand/receptor complexes. In contrast, recombinant CHO cells expressing CC-CKR2A, and membranes prepared from these cells, fail to bind detectable levels of MCP-1. However, MCP-1 stimulation of cells expressing CC-CKR2A induces a small but significant increase in intracellular Ca2+. Repeated stimulation of these cells with MCP-1 leads to a potentiation of the response to a level comparable to that seen in cells expressing CC-CKR2B. These observations suggest that the levels of cell surface CC-CKR2A are controlled by novel mechanisms.

Animals↗
PubMed1996

A heterologous assay for measuring prolactin in pituitary extracts and plasma from Australian flying foxes (genus Pteropus).

A sensitive heterologous assay was developed to measure prolactin-like activity in Pteropus alecto, P. poliocephalus, and P. scapulatus, Australian flying foxes. Adapted from an established radioimmunoassay for rabbit PRL, it utilises the well-characterised, polyclonal antiserum 33/9 (guinea pig anti-human prolactin). In the assay, pituitary extracts from P. alecto, P. poliocephalus, and P. scapulatus diluted in parallel with ovine prolactin standards, although absolute levels estimated were low. Its usefulness for investigating the role of prolactin in reproduction and seasonality in flying foxes was tested. In a survey of pituitary extracts collected from both sexes of all three species, prolactin was higher in females than in males (P < 0.001). In the few specimens from juveniles, mean prolactin levels in pituitary and plasma were similar to those of adults. Plasma and pituitary samples both contained higher concentrations of prolactin during late pregnancy (P. scapulatus, plasma P < 0.01; pituitary P < 0.01) and lactation (P. poliocephalus, plasma P < 0.005; pituitary P < 0.05) in mature females. Plasma prolactin increased at about the time of parturition, but returned to nonpregnant levels rapidly if lactation was not established. In lactating females, plasma prolactin was suppressed by temporary removal of the sucking young, and was slow to recover after the young was returned to the nipple. Pharmacological responses were tested in pregnant P. poliocephalus: plasma prolactin was low following bromocriptine administration and elevated following domperidone. Prolactin is concluded to play significant roles in the reproductive physiology of female flying foxes and, as in other species, is under dopaminergic regulation.

Animals↗
PubMed1996

Co-activation and tension-regulating phenomena during isokinetic knee extension in sedentary and highly skilled humans.

The aim of this study was to examine isokinetic torque produced by highly skilled (HS) and sedentary (S) human subjects, during knee extension, during maximal voluntary and superimposed electrical activation. To verify the level of activation of agonist (vastus lateralis, VL, and vastus medialis, VM) and antagonist muscles (semi-tendineous, ST), during maximal voluntary activation, their myo-electrical activities were detected and quantified as root mean square (rms) amplitude. Ten HS and ten S subjects performed voluntary and superimposed isometric actions and isokinetic knee extensions at 14 angular velocities (from -120 to 300 degrees*s(-1)). The rms amplitude of each muscle was normalized with respect to its rms amplitude when acting as agonist at 15 degrees*s(-1). Whatever the angular velocity considered, peak torque and constant angular torque at 65 degrees of HS were significantly higher (P <0.05) than those of S. Eccentric superimposed torque of S, but not HS, was significantly higher (P <0.05) than voluntary torque at -120, -90, - 60 and - 30 degrees*s(-1) angular velocities. For a given velocity, the rms amplitude of VL and VM were significantly lower (P <0.05), during eccentric than during concentric actions, in S, but not in HS. However, whatever the angular velocity, ST co-activation in HS was significantly lower (P < 0.05) than in S. We concluded that co-activation phenomenon could partly explain differences in isokinetic performances. Differences between voluntary and superimposed eccentric torques as well as lower agonist rms amplitude during eccentric action in S, support the possibility of the presence of a tension-regulating mechanism in sedentary subjects.

Adult↗
PubMed1996

Characterisation of atypical biotype 3, serotype O:3 Yersinia and development of a simple identification scheme.

Five clinical strains of Yersinia isolated in Japan and identified as atypical biotype 3 or biotype 3B, serotype O:3, phage type II (3*/O:3/II) Yersinia enterocolitica were characterised since the biochemical reactions of these strains indicate they might also belong to the species Yersinia bercovieri. Biochemical tests, characterisation of the beta-lactamases and DNA-DNA hybridization studies provided strong evidence indicating that these strains should be classified as Yersinia enterocolitica. A simple scheme combining a disc diffusion test and four biochemical tests was devised for identification of these atypical strains.

Acetaminophen↗
PubMed1996

A beta (25-35) peptide displays H2O2-like reactivity towards aqueous Fe2+, nitroxide spin probes, and synaptosomal membrane proteins.

Amyloid beta peptides (A beta s) are found in abnormally high accumulations in brains of persons with Alzheimer's disease, and are believed to contribute to cognitive decline in this disorder. Synthetic A beta and its peptide fragment 25-35 [A beta (25-35)] are toxic to cells in culture; however, the exact mechanism of amyloid peptide toxicity is not known. An emerging hypothesis contends that A beta toxicity results from peptide-mediated free radical reactions and generation of reactive oxygen species. Recently, we reported that reactivity of A beta toward the oxidation-sensitive enzyme glutamine synthetase is related to the peptide's reactivity toward the spin trap phenyl-tert-butyl nitrone (PBN). Neuronal damage may be due, in part, to oxidative processes initiated by amyloid-derived free radicals species. This work presents evidence from electron paramagnetic resonance (EPR) spin labeling techniques and spectrophotometric assays that a portion of synthetic A beta (25-35) demonstrates hydrogen peroxide-like reactivity toward Fe2+, nitroxide spin probes, and neocortical synaptasomal membrane proteins. These results are discussed with reference to free radical membrane damage and neurotoxicity in Alzheimer's disease.

Alzheimer Disease↗
PubMed1996

A simple device for closure of fasciotomy wounds.

Early decompressive fasciotomy is essential in the prevention of the sequelae of compartment syndrome. Many techniques have been described for the closure of the fasciotomy wound, and controversy exists as to which method is the best. Primary closure is often impossible secondary to tissue retraction and edema. Split-thickness skin grafting leaves a thin, insensate, and often aesthetically unpleasing result. Gradual mechanical dermal apposition has been used with increasing frequency, and has been shown to be effective in the closure of fasciotomies, but often takes 7-10 days for closure. We present our experience with the STAR, a mechanical method of fasciotomy wound closure that is effective in 2-4 days, and is extremely simple to use.

Adolescent↗
PubMed1996

Impact of childhood abuse history on psychological symptoms among male and female soldiers in the U.S. Army.

The long-term psychological effects of four different types of childhood maltreatment were examined among 1,072 male and 305 female soldiers on active duty in the United States Army. The predictor variables included four subscales from the Childhood Trauma Questionnaire (CTQ)-(1) physical-emotional abuse, (2) sexual abuse, (3) emotional neglect, and (4) physical neglect. An additional sexual abuse variable based on the four screening questions developed by Finkelhor, Hotaling, Lewis, and Smith (1990) was also included. Outcome was measured by the Brief Symptom Inventory and a dissociation scale developed by Briere and Runtz (1988). MANOVAs were conducted for each outcome measure. Physical-emotional abuse contributed to most of the effects. However, sexual abuse contributed additional significant effects to all of the subscales. In general, males and females showed similar outcomes, but certain gender differences were noted.

Adolescent↗
PubMed1996

Effect of initial posture on biomechanical adjustments associated with a voluntary leg movement in rock climbers.

This study compares the biomechanical adjustments following a leg displacement in vertical and horizontal position on expert rock climbers. The results show a non-diagonal pattern in the vertical condition and a diagonal one in the horizontal condition. A multi-link analysis shows that the non-diagonal pattern displayed by expert climbers in the vertical condition resulted in a new distribution of body weight to preserve the possibility of moving any limb from the three legged stance. Conversely, in the horizontal condition, the diagonal pattern appears to be strongly dominated by mechanical and anthropometric factors.

Adult↗