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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 343 records · Page 19Linked to original sources
PubMed1994

Localization of neuronal and glial glutamate transporters.

The cellular and subcellular distributions of the glutamate transporter subtypes EAAC1, GLT-1, and GLAST in the rat CNS were demonstrated using anti-peptide antibodies that recognize the C-terminal domains of each transporter. On immunoblots, the antibodies specifically recognize proteins of 65-73 kDa in total brain homogenates. Immunocytochemistry shows that glutamate transporter subtypes are distributed differentially within neurons and astroglia. EAAC1 is specific for certain neurons, such as large pyramidal cortical neurons and Purkinje cells, but does not appear to be selective for glutamatergic neurons. GLT-1 is localized only to astroglia. GLAST is found in both neurons and astroglia. The regional localizations are unique to each transporter subtype. EAAC1 is highly enriched in the cortex, hippocampus, and caudate-putamen and is confined to pre- and postsynaptic elements. GLT-1 is distributed in astrocytes throughout the brain and spinal cord. GLAST is most abundant in Bergmann glia in the cerebellar molecular layer brain, but is also present in the cortex, hippocampus, and deep cerebellar nuclei.

Amino Acid Sequence↗
PubMed1994

The influence of electrostimulation on mechanical and morphological characteristics of the triceps surae.

The present study assessed the effects of training using electrostimulation of muscle (EMS) on the torque-angular velocity and torque-angle relationships, and the cross-sectional area (CSA) of the triceps surae. Twelve physical education students, divided into two groups (6 controls, 6 experimental), participated in the experiment. The EMS sessions were undertaken using a 'Complex-type' stimulator. Flexible elastomer electrodes were used. The current used discharged pulses lasting for 200 microseconds at a frequency of 70 Hz. The durations of contraction and rest were 5 and 15 s, respectively. The session lasted for 10 min for each muscle. The training regimen was three sessions per week for 4 weeks. Biomechanical tests were performed with the Biodex (Biodex Corporation, Shirley, NY, USA) isokinetic ergometer. Plantar flexions of the ankle over a concentric range of voluntary contractions were performed at different angular velocities (1.05, 2.10, 3.14, 4.20, 5.23 and 6.28 rad s-1) and maximum voluntary isometric contractions were held for 5 s at several ankle flexion angles (-30 degrees, -15 degrees, 0 degree and 15 degrees; 0 degree corresponds to foot flexion of 90 degrees relative to the leg axis). The peak value of the torque was recorded. Morphological tests consisted of measuring the CSA of the triceps surae on the right leg, 15 cm below the tibial protuberance, by a computerized tomography technique. The torque-velocity relationship was seen to shift significantly upwards after EMS training. The increase in the isometric torque observed after EMS training was greater in dorsiflexion than in plantarflexion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Videothoracoscopy in trauma: early experience.

We present a series in which videothoracoscopy was used to evaluate and manage patients after thoracic trauma. We used this technique in 11 patients with thoracic injuries. We describe 5 representative cases. It was used successfully in 10 of 11 patients. Indications included evaluation of ongoing hemothorax, evacuation of clotted hemothorax and empyema, and decortication for persistent airleak. Etiologies included blunt trauma, stab wounds, and gunshot wounds.

Adult↗
PubMed1994

Composition of meal influences changes in postprandial incremental glucose and insulin in healthy dogs.

Postprandial hyperglycemia and insulin secretion depend on many factors, such as food composition, carbohydrate type and processing. The purpose of this study was to evaluate the effects of foods differing in composition in nonobese clinically normal dogs. These dogs were offered in a single meal one of the four foods. Blood samples were collected before feeding and during the 180 min after the meal. Plasma glucose and insulin concentrations were determined. The integrated areas under the postprandial glucose and insulin response curves were calculated. Times to response peaks, maximum plasma insulin elevation, area under the insulin response curve and the insulinemic index differed between dog foods. Crude fiber content had no significant effect. The time to glucose peak was higher and the time to insulin peak lower with the food highest in protein and ether extract content. The time to glucose peak was correlated to protein, fat and nitrogen-free extract content of foods, whereas the time to insulin peak and the area under the insulin curve were correlated to protein and nitrogen-free extract.

Animal Feed↗
PubMed1994

Can ultrasound replace diagnostic peritoneal lavage in the assessment of blunt trauma?

Diagnostic peritoneal lavage (DPL) and computed tomography (CT) are the primary diagnostic modalities in the evaluation of patients with suspected blunt abdominal trauma (BAT). Diagnostic peritoneal lavage is fast and accurate but associated with complications. Computed tomography is also accurate, yet requires that patients be stable and transportable. A prospective study was designed to determine the utility of emergency ultrasound (US) studies in the initial assessment of BAT. Two hundred acutely injured patients with suspected BAT were evaluated with US. Patients were eligible for the study if they met trauma criteria and had suspected BAT. Subsequently, without knowledge of the US results, DPL or CT was performed. Ultrasound showed a sensitivity of 83%, a specificity of 100%, and an accuracy of 97% in detecting intra-abdominal injuries. Six injuries were missed but only one was felt to be significant. If US had been used in all 200 patients, 199 would have had appropriate care. We conclude US is reliable in the detection of free intraperitoneal fluid and may be used in place of DPL or CT.

Abdominal Injuries↗
PubMed1994

Relative efficiency of leucocyte removal procedures for the production of leucocyte-poor red cell concentrates assessed by flow cytometry.

Flow cytometry was used to: (1) determine residual leucocyte numbers in red cell suspensions following the range of leucocyte depletion procedures used in our organisation, and (2) to characterize phenotypically the leucocytes using direct immunofluorescence with monoclonal antibodies to cell surface receptors. Under the conditions used, a lower limit of detection of 2.5 leucocytes per microliter (equivalent to 3.43 log10 or 99.96% removal) could be achieved. Filtration through polyester filters was found to remove up to > 99.96% of the initial leucocytes; however, a significant differential efficacy was observed between filters from different manufacturers even when filters with similar costs were compared. The order of filter brands with respect to leucocyte removal found was Pall BPF4 = Erypur Optima G-O > Sepacell R500 > Pall RC50. Phenotyping revealed that increasing filtration efficacy was associated with a preferential removal of lymphocytes; conversely, a second filtration over one brand of filter allowed proportionately more lymphocytes to pass through compared with the first filtration. A saline wash following filtration removed a further 0.5% of the initial leucocyte content, and was associated with a preferential loss of granulocytes. Freeze-thawing the red cell suspension removed fewer leucocytes (96.3%) than did filtration (98.74% to > 99.6%) or filtration followed by washing (99.22%), and also led to preferential loss of granulocytes. Flow cytometry provides a reliable tool for the quality control of leuco-depleted red cells, and allows a qualitative assessment of the residual leucocytes. This information is of value in choosing procedures aimed at decreasing the risk of alloimmunisation and post-transfusion reactions.

Cell Separation↗
PubMed1994

The ovarian-uterine vasculature in relation to unilateral endometrial growth in flying foxes (genus Pteropus, suborder Megachiroptera, order Chiroptera).

The ovarian-uterine vasculature was examined in three Australian species of flying fox (Pteropus scapulatus, P. poliocephalus and P. alecto). Vascular casts and histological sections were used to determine the relationship between the blood supply and the localized endometrial reaction, which occurs ipsilateral to the ovulating ovary. The ovarian artery coils extensively just cranial to the ovary, gives off a branch to the ovary and continues caudally as the major vessel supplying the cranial tip of the uterus, where it anastomoses with the smaller uterine artery. The coil of the ovarian artery is completely enclosed by a venous sinus that drains the cranial pole of the ovary. The ovary is heavily encapsulated, with primordial follicles restricted to the caudal pole; thus, the corpus luteum is completely internal and placed cranially, close to the coil of the ovarian artery. This arrangement would allow countercurrent or crosscurrent transfer of ovarian steroids from ovarian vein to ovarian artery and on to the cranial tip of the ipsilateral uterine horn. The steroids could thus reach high concentrations locally and generate localized endometrial growth. Cranial to the coil, the ovarian artery is enclosed in a venous sinus that derives from uterine as well as ovarian veins. This would allow countercurrent transfer of bioactive substances from uterus to ovary.

Animals↗
PubMed1994

Tumor oxygenation after 1) carbogen and/or perflubron emulsion administration in tumor xenografts 2) carbogen administration in patients.

This study examines the changes in tumor pO2 distribution assessed by polarography (KIMOC 6650, Eppendorf) in 1) two human tumor xenografts after carbogen inhalation with or without a perflubron (perfluorooctylbromide) emulsion (Oxygent, Alliance Pharmaceutical corp.) and in 2) human head and neck carcinomas after carbogen inhalation. Mice bearing HRT18 or NA11+ tumors were restrained and their body temperature was kept constant. Perflubron emulsion (4 ml/kg) was injected i.v. in the mice. In patients, oxygenation of the head and neck metastatic lymph nodes was assessed before and/or during carbogen exposure. The distribution of pO2 values shifted upwards during carbogen exposure in both animals and patients while the proportion of low pO2 values decreased. The maximal effect was obtained with patients after 1 to 6 minutes of carbogen exposure, but 4 patients still maintained very low pO2s. Carbogen plus 4 ml/kg perflubron emulsion was more efficient than carbogen alone for increasing hypoxic tumor pO2 in animals. If the animals data could be extrapolated to humans, then the effect of carbogen on tumor oxygenation should be increased by perflubron emulsion administration.

Administration, Inhalation↗
PubMed1994

[Modelling of viscosity equivalent factor in the human muscle during muscular shortening].

The aim of this study was to calculate the theoretical variation of the non linear damping factor (B) as a function of the muscle shortening velocity. The theoretical variation of the B factor was determined from a muscle model which consists of a contractile component in parallel with a viscous damper both in series with an elastic component, and by using the characteristic equation of the force-velocity curve. In this muscle model, the viscous element modeled the inability of the muscle to generate as a big contracting force (while shortening) as possible under isometric conditions. The results show that the theoretical behaviour of the B factor was dependent on the shortening velocity and on the af parameter which varies according to the muscle fibre type composition and affects the curvature of the force-velocity curve.

Humans↗
PubMed1994

"Checkerboard" DNA-DNA hybridization.

A method is introduced for hybridizing large numbers of DNA samples against large numbers of DNA probes on a single support membrane. Denatured DNA from up to 43 samples was fixed in separate lanes on a single membrane mounted in a Miniblotter 45. The membrane was then rotated 90 degrees in the same device, which enabled simultaneous hybridization with 43 different DNA probes. Hybridizations were also performed on lysates of bacterial cells blotted to membranes. A MiniSlot device allowed lysates loaded in parallel channels to be aspirated through the membrane, depositing horizontal lanes on the membrane surface. Hybridizations were performed in vertical lanes with either digoxigenin-labeled whole genomic probes or 16S rRNA-based oligonucleotide probes directly conjugated to alkaline phosphatase. The method permits the simultaneous determination of the presence of multiple bacterial species in single or multiple dental plaque samples, thus suggesting its usefulness for a range of clinical or environmental samples.

Base Sequence↗
PubMed1994

Antibodies to high mobility group proteins in systemic sclerosis.

OBJECTIVE: To determine the prevalence of autoantibodies to high mobility group (HMG) proteins in systemic sclerosis (SSc). METHODS: One hundred ninety-seven unselected sera from patients diagnosed as SSc (n = 180) or Raynaud's phenomenon (RP) (n = 17) were tested for HMG autoantibodies by ELISA and immunoblotting. RESULTS: Seventy-one of the 180 (39.0%) SSc sera bound to HMG proteins in an ELISA: 56 (31%) to HMG-1 and/or HMG-2; 29 (16%) to HMG-14/17. In the same assay, 7 of 17 RP sera (41%) bound to HMG proteins: 4 (23%) to HMG-1 and/or HMG-2, and 5 (29%) to HMG-14/17. The specificity of HMG binding was confirmed by immunoblotting. CONCLUSION: Antibodies to HMG proteins, particularly to HMG-1 and HMG-2 are found in about 1/3 of SSc Sera. Since HMG-1 and HMG-2 have a role in transcription, these observations further implicate transcriptional complexes as targets of autoantibodies in scleroderma. This is the first published report of HMG autoantibodies in scleroderma.

Autoantibodies↗
PubMed1994

Correlation between radiosensitivity, percentage hypoxic cells and pO2 measurements in one rodent and two human tumor xenografts.

Computerized pO2 histography has been used to measure the intratumor pO2 in patients for the past few years, and there is now evidence that these tumors contain hypoxic cells. One of the major questions that remains to be answered is the relevance of such data to radiosensitivity. The present study looks for a correlation between intratumor pO2, the percentage of hypoxic cells in the tumor and the radiosensitization induced by carbogen and/or the oxygen carrier, perflubron emulsion. Two human tumor xenografts (HRT18, Na11+) and one rodent tumor (EMT6) were used. The radiosensitivity (clonogenic assay) and the oxygen tension (computerized pO2 histography) were measured. All experiments were performed under similar conditions. Carbogen increased tumor radiosensitivity; sensitization was greatest when 4 ml/kg perflubron emulsion was used in conjunction with carbogen. The pO2 distribution was shifted to higher pO2 values in the tumors whatever the treatment; the shift was greater for perflubron emulsion plus carbogen. The low pO2 values (< 0.4 kPa) were lost for the HRT18 cells. A correlation (EMT6, HRT18) or a link (Na11+) between the radiosensitization and the oxygen tension measurements was found for values below 1.07 or 1.33 kPa. A trend between the percentage of hypoxic cells and pO2 measurements was found taking into account pO2 measurements comprised between 0.27 and 0.67 kPa.

Adenocarcinoma↗
PubMed1993

Radiation Therapy Oncology Group: radiosurgery quality assurance guidelines.

A multidisciplinary Radiation Therapy Oncology Group (RTOG) task force has developed quality assurance guidelines for radiosurgery. The purpose of the guidelines are fourfold: (1) To ensure that participating institutions have the proper equipment and appropriate technique(s) to administer radiosurgery; (2) to outline a standard data set for each treated patient to assess protocol compliance; (3) to define minor and major deviations in protocol treatment; and (4) to set forth clinical data necessary to determine treatment efficacy, including failure patterns, and treatment toxicity. These guidelines are being implemented into active and developing radiosurgery protocols.

Brain Neoplasms↗