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Biomedical subjects

E Martin

Publications and source records attributed to E Martin.

At least 415 records · Page 23Linked to original sources
PubMed1994

Time course of action and recovery of rocuronium bromide in children during halothane anaesthesia--a preliminary report.

In this preliminary study, two groups of 15 patients, aged 1-4 years and 5-10 years respectively, received one of four doses of rocuronium (0.12, 0.17, 0.22 or 0.27 mg kg-1) and when block was maximal a supplementary dose to bring them all to a total of 0.5 mg kg-1. In half the patients, the block was reversed with atropine and neostigmine at a T1 recovery of 25%. The remainder were allowed to recover spontaneously. The total dose produced a block of 95-100% in all patients. The clinical duration of action was shorter under halothane anaesthesia in children (mean 15 min approximately) than has previously been reported in adults under intravenous anesthesia. Mean spontaneous recovery time from T1 25% to a train-of-four ratio of 0.7 was about 11 min. Neostigmine doubled the rate of recovery. There was a moderate increase in heart rate in the younger age range.

Androstanols↗
PubMed1994

Porphyrinogenic effects of atracurium, vecuronium, and pancuronium in a primed rat model.

Steroidal muscle relaxants might theoretically be contraindicated in acute hepatic porphyrias. Atracurium, on the other hand, has been proposed as the muscle relaxant of choice because of its extrahepatic degradation. To further investigate this problem, equipotent doses of atracurium, vecuronium, and pancuronium were determined in male Sprague Dawley rats, using evoked electromyography. After this pilot study, 64 rats were anesthetized, mechanically ventilated, and randomly allocated to eight groups. Animals in groups 1 through 4 received an intraperitoneal injection of arachis-oil 20 h before the experiments. For groups 5 through 8, an experimental porphyria was induced by use of the chemical substance 3,5-dicarbethoxy-1,4-dihydrocollidine (DDC), which was dissolved in arachis-oil and given 20 h prior to the beginning of the study. Rats of groups 1 and 5 served as controls; they received saline and were not given muscle relaxants throughout the experiment. For groups 2 and 6, atracurium was administered at a dosage of 4 mg/kg of body weight, followed by a continuous infusion of 15 mg/kg/h. Animals of groups 3 and 7 received vecuronium at a dosage of 1.5 mg/kg, followed by 7.5 mg/kg/h. For groups 4 and 8, pancuronium was given (0.75 mg/kg and 2.5 mg/kg/h, respectively). At the end of the 3-h study period, the liver was perfused and excised, and urine was obtained. Activity of the hepatic enzyme delta-aminolevulinic acid synthase (ALAS) and urinary concentrations of delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Aminolevulinate Synthetase↗
PubMed1994

[Hysteroscopy syndrome. Absorption of irrigation fluid in surgical hysteroscopy].

The availability of adequate endoscopic instruments has led to an increased interest in hysteroscopic surgical procedures. An electrolyte-free irrigation fluid is essential for the distention of the uterine cavity, with acceptable uterine distention occurring at 80-150 mmHg. The HSK syndrome, the intravascular absorption of a hypotonic irrigation fluid with subsequent hypotonic hyperhydration with hyponatremia, has to be considered as a risk during hysteroscopic procedures. Analogous to the TUR syndrome, intravasation occurs through the vascular spaces opened during large ablative surgical procedures resulting in the absorption of the fluid used for irrigation. Occasionally, a tear in the lower uterine segment from dilation or perforation of the uterus may expose large vascular channels. Outflow through the tubes is not a significant factor. Continuous CVP measurement allows the detection of intravascular absorption of the irrigation fluid and may be included in the routine monitoring for these procedures. The duration of the hysteroscopic procedure should be limited to 60 min. Addition of ethanol to the irrigating fluid may be suitable for early detection of fluid absorption. However, commercial solutions are not yet available.

Absorption↗
PubMed1994

Developmental changes of phosphorus metabolite concentrations in the human brain: a 31P magnetic resonance spectroscopy study in vivo.

Phosphorus magnetic resonance spectroscopy is a noninvasive method to investigate brain metabolism in vivo. ATP generally serves as an internal concentration standard for the quantification of the various phosphorus metabolites, because the ATP concentration in mammalian brains is assumed to be age independent. This presumption is based on observations made in the biochemical analysis of the developing rat brain. In the present study, metabolite concentrations were assessed with an external concentration standard. Each brain spectrum was quantified using a calibration spectrum that was acquired from a phantom after the in vivo brain measurement. Fully relaxed localized brain spectra were obtained from 16 neonates (2-28 d), 17 infants (6-20 mo), and 28 adults (22-58 y). The metabolite concentrations (in mmol/L) changed from neonates to adults: phosphomonoester from 4.5 to 3.5, inorganic phosphate from 0.6 to 1.0, phosphodiester from 3.2 to 11.7, phosphocreatine from 1.4 to 3.4, and ATP from 1.6 to 2.9. We conclude that 1) the ATP concentration in the human brain almost doubles between neonates and adults, and 2) ATP may not be used as an age-independent internal concentration standard.

Adenosine Triphosphate↗
PubMed1994

[Ondansetron--a new anesthesia relevant antiemetic?].

Ondansetron is a new selective serotonin-3-receptor antagonist which has proved to be effective in chemotherapy-induced nausea and vomiting. Initial studies evaluating the efficacy and safety of this substance for the treatment and prevention of postoperative nausea and vomiting yielded promising results. However, ondansetron's exact role in the perioperative setting still remains to be determined.

Humans↗
PubMed1994

To what extent do clinical notes by general practitioners reflect actual medical performance? A study using simulated patients.

BACKGROUND: Review of clinical notes is used extensively as an indirect method of assessing doctors' performance. However, to be acceptable it must be valid. AIM: This study set out to examine the extent to which clinical notes in medical records of general practice consultations reflected doctors' actual performance during consultations. METHOD: Thirty nine general practitioners in the Netherlands were consulted by four simulated patients who were indistinguishable from real patients and who reported on the consultations. The complaints presented by the simulated patients were tension headache, acute diarrhoea and pain in the shoulder, and one presented for a check up for non-insulin dependent diabetes. Later, the doctors forwarded their medical records of these patients to the researchers. Content of consultations was measured against accepted standards for general practice and then compared with content of clinical notes. An index, or content score, was calculated as the measure of agreement between actions which had actually been recorded and actions which could have been recorded in the clinical notes. A high content score reflected a consultation which had been recorded well in the medical record. The correlation between number of actions across the four complaints recorded in the clinical notes and number of actions taken during the consultations was also calculated. RESULTS: The mean content score (interquartile range) for the four types of complaint was 0.32 (0.27-0.37), indicating that of all actions undertaken, only 32% had been recorded. However, mean content scores for the categories 'medication and therapy' and 'laboratory examination' were much higher than for the categories 'history' and 'guidance and advice' (0.68 and 0.64, respectively versus 0.29 and 0.22, respectively). The correlation between number of actions across the four complaints recorded in the clinical notes and number of actions taken during the consultations was 0.54 (P < 0.05). CONCLUSION: The use of clinical notes to audit doctors' performance in Dutch general practice is invalid. However, the use of clinical notes to rank doctors according to those who perform many or a few actions in a consultation may be justified.

Clinical Competence↗
PubMed1993

Vaginal stenosis and sexual function following intracavitary radiation for the treatment of cervical and endometrial carcinoma.

PURPOSE: This study was designed to document the incidence and degree of vaginal stenosis, sexual activity, and satisfaction in women treated with intracavitary radiation therapy for cervical or endometrial carcinoma. METHODS AND MATERIALS: The incidence of vaginal stenosis in 90 patients treated for either cervical carcinoma (n = 42) or endometrial carcinoma (n = 48) with standard doses of intracavitary radiation from 1989 to 1992 with at least 6 months follow-up was recorded. Vaginal length was measured using a modified vaginal dilator calibrated in centimeters. Semistructured patient interviews documented pretreatment and posttreatment sexual activity and sexual satisfaction. RESULTS: Vaginal length was found to be dependent on diagnosis (cervical vs. endometrial), stage (I vs. II/III), and follow-up interval (6-12 months, 12-24 months, and > 24 months). Slightly more women reported sexual activity post vs. pretreatment (31% active pretreatment vs. 43% active posttreatment). However, 22% of women reported a decrease in sexual frequency and 37% reported a decrease in sexual satisfaction. Reports for all parameters were worse for women treated for cervical carcinoma vs. women treated for endometrial carcinoma with the exception of dyspareunia. CONCLUSION: High-dose radiation for either cervical or endometrial carcinoma at standard doses with or without hysterectomy can cause a decrease in vaginal length as compared to the normal vaginal length of 8 to 9 cm documented by Masters and Johnson. Women treated with intracavitary implants remained as sexually active postimplant as preimplant, however, coital frequency and sexual satisfaction decreased while dyspareunia increased. The decrease in vaginal length may explain in part the decrease in sexual satisfaction but cause and effect have not been established.

Adenocarcinoma↗
PubMed1993

Histidine-tagged RNA polymerase: dissection of the transcription cycle using immobilized enzyme.

A stretch of six histidine residues (His6) has been genetically fused to the C terminus of the beta' polypeptide of Escherichia coli RNA polymerase. The His6-tagged beta' subunit assembles into RNA polymerase molecules which perform all vital in vivo functions and behave qualitatively normally in vitro. The His6 tag permits rapid purification of the enzyme directly from crude cell extracts or from an in vitro reconstitution reaction by adsorption to Ni(2+)-chelating agarose resin, followed by elution with imidazole. The enzyme bound to the matrix remains transcriptionally active. The immobilized enzyme can withstand repeated buffer changes without substantial activity loss and permits controlled stepwise 'walking' of the transcriptional complex along the DNA template, and isolation of defined intermediates in the transcription cycle. The immobilized RNA polymerase provides a powerful experimental system for structural and functional analysis of RNA polymerase and its interaction with regulatory factors.

Amino Acid Sequence↗
PubMed1993

Determination of saturation factors in 31P NMR spectra of the developing human brain.

In order to assess the influence of longitudinal relaxation on previously reported variations in 31P NMR signals during brain development, we used an accelerated two-point technique to determine T1 at 2.35 Tesla in 8 min. Comparison between 10 normal neonates (age range 37-46 weeks postconception) and 10 healthy infants (age range 80-157 weeks postconception) indicated that T1 does not vary substantially during the first year of life, except in the phosphomonoester (PME) region of the spectra. T1 of total PME decreases with age which we could explain by its variable multicomponent nature: The signal from (unresolved) components at the downfield shoulder of PME (attributed mostly to phosphorylethanolamine at 6.72 ppm) with a T1 of at least 6.4 s decreases with age relative to contributions from other phosphomonoester compounds resonating predominantly at the upfield side of the peak (approximately 6.3 ppm), with T1 below 2.9 s. Because the T1 heterogeneity of PME may depend on its relative composition, quantitative 31P NMR spectroscopy may require an assessment of the influence of longitudinal relaxation on the signal amplitudes in each measurement.

Brain↗
PubMed1993

Evaluation of NR-LU-10 with the Neoprobe gamma detector in a mouse model.

The Neoprobe Model 1000 hand-held gamma detector, in combination with the murine monoclonal antibody (MAb) B72.3 can successfully intraoperatively target both primary and recurrent colorectal cancer. Because of the shortcomings of this system (length of time needed to clear unbound MAb and heterogeneous staining of cancer cells), new MAbs are under investigation. NR-LU-10 IgG and its FAB fragment were evaluated with the Neoprobe gamma detector in a nude mouse model. NR-LU-10 is a pancarcinoma IgG2b antibody that recognizes an oncofetal glycoprotein antigen that is expressed by most carcinomas. Animals were injected intraperitoneally with 125I-labeled IgG, 125I, or technetium 99m (99mTc)-labeled Fab fragment. The Neoprobe gamma detector and standard gamma well counts provided biodistribution and pharmacokinetic data. The Fab fragment achieved a 5:1 tumor to blood-pool background (BPB) ratio in only 66 hr, whereas the whole MAb required 14 days. Technetium did not appear to be an adequate isotope for this system because of its short half-life. Autoradiographs performed for both the 125I-labeled NR-LU-10 IgG and its 125I-labeled Fab fragment (but not 99mTc-labeled Fab) localized well in this model and gave adequate tumor to BPB and tissue ratios. Use of the 125I-labeled Fab significantly decreased the time required for clearance of the MAb radionuclide complex from the blood and tissue background, thus providing earlier tumor localization in the Radioimmunoguided Surgery (RIGS) system.

Animals↗
PubMed1993

Prevention of catheter-related infections by antiseptic bonding.

A novel catheter pretreated with the antiseptics chlorhexidine and silver-sulfadiazine, designed to reduce catheter-related colonization and infection, was tested in both in vitro and in vivo studies. In vitro experiments demonstrated the long-lasting antibacterial properties of this catheter. For the in vivo study a total of 40 rats divided into different experimental groups were used. Colonization rates of both antiseptic bonded (AS) and control (C) catheters were assessed either three (-3) or seven (-7) days after implantation and local challenge using live Staphylococcus epidermidis ATCC 35984 with 10(7) colony-forming units (cfu) per inoculum. At the time of removal, catheters, organ specimens, and blood samples were taken for cultivation. Significant reductions in the magnitude of colonization of the antiseptic catheters by the test organism were observed in all groups. The average number of cfu colonizing control segments exceeded those found on the treated catheter segments by log 3 (C3/AS3) and log 5 (C7/AS7), respectively (C3: 1.2 x 10(6) +/- 4.1 x 10(5) cfu/segment and AS3: 1.8 x 10(3) +/- 6.6 x 10(2); C7: 2.7 x 10(5) +/- 8.6 x 10(4) and AS7: 1.1 +/- 0.7; mean +/- standard error of the mean, all differences between matching groups statistically significant, Wilcoxon rank sum test, P < 0.0001). These data suggest that antiseptic catheters may substantially decrease the magnitude of catheter-related microbial colonization and subsequent catheter-related infections and may offer a more effective alternative to current methods.

Animals↗
PubMed1993

A guide to the use of pore-forming toxins for controlled permeabilization of cell membranes.

Depending on the size of the pores one wishes to produce in plasma membranes, the choice will probably fall on one of the three toxins discussed above. S. aureus alpha-toxin should be tried first when pores of 1-1.5 nm diameter are required. This is generally the case when Ca2+ and nucleotide dependence of a given process is being studied. If alpha-toxin does not work, this is probably due to the fact that the toxin either does not produce pores, or that the pores are too small. In this case, high concentrations of alpha-toxin should be tried. If this still does not work, we recommend the use of HlyA. When very large pores are to be created, e.g. for introduction of antibodies into the cells, SLO or another member of this toxin family are the agents of choice. SLO preparations need to be checked for presence of protease contaminants. Tetanolysin currently offers advantages since it is protease-free, and the size of the pores can probably be controlled by varying the toxin dose. Methods for assessing the size of pores created by such agents have been published in the recent literature, and the appropriate papers can be consulted whenever the need arises.

Bacterial Proteins↗
PubMed1993

Prenatal brain atrophy due to a giant vein of Galen malformation.

We report a full-term newborn girl with a giant vein of Galen malformation and extreme cerebral atrophy of prenatal origin. She presented on the 3rd day of life with intractable congestive heart failure. The diagnosis of the vascular malformation was confirmed by ultrasound and magnetic resonance imaging.

Atrophy↗
PubMed1993

Early pattern recognition in severe perinatal asphyxia: a prospective MRI study.

On the basis of MRI examinations in 88 neonates and infants with perinatal asphyxia, we defined 6 different patterns on T2-weighted images: pattern A--scattered hyperintensity of both hemispheres of the telencephalon with blurred border zones between cortex and white matter, indicating diffuse brain injury; pattern B--parasagittal hyperintensity extending into the corona radiata, corresponding to the watershed zones; pattern C--hyper- and hypointense lesions in thalamus and basal ganglia, which relate to haemorrhagic necrosis or iron deposition in these areas; pattern D--periventricular hyperintensity, mainly along the lateral ventricles, i.e. periventricular leukomalacia (PVL), originating from the matrix zone; pattern E--small multifocal lesions varying from hyper--to hypointense, interpreted as necrosis and haemorrhage; pattern F--periventricular centrifugal hypointense stripes in the centrum semiovale and deep white matter of the frontal and occipital lobes. Contrast was effectively inverted on T1-weighted images. Patterns A, B and C were found in 17%, 25% and 37% of patients, and patterns D, E and F in 19%, 17% and 35%, respectively. In 49 patients a combination of patterns was observed, but 30% of the initial images were normal. At follow-up, persistent abnormalities were seen in all children with patterns A and D, but in only 52% of those with pattern C. Myelination was retarded most often in patients with diffuse brain injury and PVL (patterns A and D).

Asphyxia Neonatorum↗