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Biomedical subjects

J Peters

Publications and source records attributed to J Peters.

At least 361 records · Page 20Linked to original sources
PubMed1994

[Model tests for effectiveness assay of disinfectants on surfaces. III. Dependence of test results on the type of substances and the test microbes (Staphylococcus aureus, Mycobacterium terrae)].

A new test method for surface disinfectants was applied to investigate the efficacy of the most important active components of disinfectants to Staphylococcus aureus and Mycobacterium terrae. The test germs were embedded in coagulated blood. Frosted glass served as test surface. The disinfection was performed by applying a fixed amount of the disinfectant and mixing it with the contamination by rubbing. The number of surviving germs was determined quantitatively. Generally, the two test germs showed a distinctly different behaviour towards the active substances applied. Mycobacteria proved to be clearly more resistant than staphylococci, except with formaldehyde and the cresol-soap solution. The formaldehyde, the mycobacteria were only a little more resistant, while to cresol-soap solution they were even a little more sensitive than were staphylococci. Compounds containing active chloride showed a sufficient effect on mycobacteria only if the consumption of the active component by blood was nearly excluded. The quaternary ammonium compound and glyoxal, even the high concentrations, showed a totally insufficient efficacy to mycobacteria. The results shall provide the basis for a new guideline to be established by the Federal Health Office concerning the efficacy testing of surface disinfectants effective against mycobacteria, especially tuberculosis bacteria.

Chlorine↗
PubMed1994

[Demonstration os isoagglutinins in intravenously applicable immunoglobulin preparations].

Intravenous immunoglobulins (IvIg) contain not only the declared antibodies against pathogenic microorganisms but also all the other antibodies of the blood donors, e.g. against erythrocytic antigens. We tested 14 IvIg from 7 manufacturers (together 40 charges) for isoagglutinins and irregular blood group antibodies. To ameliorate the reading of our tests we used the gel-centrifugation method (ID-Microtyping System, Fa. Diamed, Bensheim, FRG). Isoagglutinins in the IvIg can influence blood group serologic tests. Therefore we point to the potential danger of misinterpretation of a positive direct antiglobulin test. In rare cases, hemolytic reactions after administration of high doses of IvIg might occur.

Agglutinins↗
PubMed1993

CSF diazepam binding inhibitor and schizophrenia: clinical and biochemical relationships.

Diazepam-binding inhibitor (DBI) is a 9-kD neuropeptide that interacts with the benzodiazepine (BZD) binding sites of the neuronal gamma-aminobutyric acid type A (GABAA) receptor and with the glial mitochondrial BZD receptor (MBR). We explored the involvement of CSF DBI-LI in schizophrenia, based on the potential role of GABA in the negative symptoms associated with schizophrenia, the relationship of its receptors with dopamine and norepinephrine release, and the proposed therapeutic efficacy of BZDs in schizophrenia. Clinical data, CSF DBI-LI and CSF monoamine measures were obtained in 65 drug-free male chronic (DSM-IIIR) schizophrenic patients, 53 of whom were also tested prior to haloperidol withdrawal. Following haloperidol withdrawal, CSF DBI-LI increased significantly. Drug-free CSF DBI-LI did not correlate with CSF monoamines. CSF DBI-LI was significantly higher in paranoid compared to chronic undifferentiated schizophrenic patients. The data suggest that DBI may have a symptom modulatory rather than an etiological role in schizophrenia.

Adult↗
PubMed1993

Swelling of glial cells in lactacidosis and by glutamate: significance of Cl(-)-transport.

Swelling of glial and nerve cells is characteristic of brain damage in cerebral ischemia or trauma. The therapeutical efficiency of inhibition of Cl(-)-transport by a novel antagonist, the diuretic torasemide, on cytotoxic swelling of glial cells from lactacidosis, or glutamate was analyzed. Lactacidosis and the interstitial accumulation of glutamate are hallmarks of the pathophysiological alterations in ischemic or traumatic brain tissue. C6 glioma cells harvested from culture and suspended in a physiological medium were either exposed to pH 6.2, or 5.0 by lactic acid, or exposed to 1 mM glutamate at normal pH. Cell swelling and viability were quantified by flow cytometry. Lactacidosis of pH 6.2 led to an increase in cell volume to 117.9 +/- 0.7% within 60 min. Torasemide (1 mM) inhibited the swelling response by 50% (P < 0.01). Cell swelling at pH 5.0, although more severe, was again attenuated by torasemide (P < 0.01). No effect was seen on the decrease in cell viability at this level of acidosis. Addition of glutamate led to a steady increase in cell volume which, contrary to cell swelling from lactacidosis, was not inhibited by torasemide. Inhibition of cell swelling from acidosis by this diuretic may be attributed to blocking of Cl-/HCO3- exchange mechanisms activated by acidosis. The lack of effect by torasemide in glial cell swelling from glutamate indicates operation of a different mechanism inducing cell swelling, for example cellular accumulation of the amino acid together with Na+ and water.

Acidosis, Lactic↗
PubMed1993

Syndrome of Rochalimaea henselae adenitis suggesting cat scratch disease.

OBJECTIVE: To describe a clinical syndrome of cat scratch disease caused by Rochalimaea henselae, including methods for isolation of the organism from tissue and for identification. DESIGN: Case series. SETTING: U.S. Air Force referral hospital infectious diseases clinic. PATIENTS: Two previously healthy patients. MAIN MEASUREMENTS AND RESULTS: Two immunocompetent patients who had handled cats developed unilateral upper-extremity adenitis associated with a distal papular lesion and fever. The adenitis and distal lesions persisted and progressively worsened. Cultures of the involved lymph nodes from both patients grew R. henselae, a recently described organism associated with bacillary angiomatosis and peliosis hepatis in human immunodeficiency virus-infected patients and with bacteremia in immunocompromised and immunocompetent hosts. The organism was characterized as oxidase negative and X-factor dependent and had a characteristic pattern in analysis of whole-cell fatty acids differing from Afipia felis, a bacterium that has been associated with cat scratch disease. The identity of the isolate was confirmed by analysis of whole-cell fatty acids using gas chromatography and by amplification of the citrate synthetase gene sequence and analysis of the polymerase chain reaction-amplified product. The organisms were broadly susceptible to a variety of antimicrobials by broth microdilution; however in-vitro resistance to first-generation cephalosporins correlated with clinical failure of therapy. CONCLUSION: Rochalimaea henselae can be a cause of cat scratch disease in immunocompetent patients.

Adult↗
PubMed1993

Expression of the mouse ren-2 gene in the small intestine is regulated by food intake.

The existence of a local renin/angiotensin system in the intestine of mammals is speculative despite the known importance of angiotensin II for water and electrolyte homeostasis. We demonstrate the presence of ren-2 transcripts in the small intestine of DBA/2 mice. The marked expression of the ren-2 gene is blunted tissue-specifically by starvation, corroborating a local renin/angiotensin system in this organ.

Animals↗
PubMed1993

An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells.

Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concentration of Photofrin in the extracellular medium (r = 0.94; P < 0.001). Subsequent to increasing intervals of Photofrin exposure, cells were irradiated with laser light at 630 nm (40 mW/cm2, 4J). Cell viability as evaluated by trypan blue exclusion was significantly decreased with increasing concentrations of Photofrin in the medium, and significantly correlated with CFI during the plateau phase. After photodynamic treatment (PDT) cell fluorescence was reduced by about 15%. This was neither dose- nor time-dependent. On the basis of these findings we propose that CFI indicates photosensitizer uptake. This is also supported by the relation between CFI and phototoxicity. The latter also suggests that CFI might be useful to predict the PDT in vivo efficacy by this in vitro model. Besides measurements of photosensitizer uptake and cell photoxicity, the model demonstrates an excellent opportunity to study the molecular mechanisms of action associated with PDT.

Animals↗
PubMed1993

Anaplastic carcinoma of the thyroid following radio-iodine therapy.

We describe a 79 year old lady who presented with a cytologically confirmed anaplastic carcinoma of the thyroid gland eleven years after administration of radio-iodine for thyrotoxicosis. This is, we believe, the first such occurrence documented in the Irish literature.

Aged↗
PubMed1993

Swelling and death of neuronal cells by lactic acid.

Lactacidosis occurring in cerebral ischemia or trauma is a major mechanism of cytotoxic brain edema and brain damage. Respective effects of lactacidosis were currently analyzed in vitro by employment of the murine neuronal cell line, Neuro-2A, in order to obtain a better understanding of specific mechanisms underlying cell swelling and cell death in comparison with glial cells. The cells were suspended in a physiological medium in the presence of lactic acid at increasing concentrations. Levels of acidosis reaching from pH 6.8-5.6 were obtained while other parameters, such as osmolarity and electrolyte concentrations, were maintained in the physiological range. Assessment of cell swelling and cell viability using exclusion of propidium iodide was made by flow cytometry with employment of an advanced Coulter system. Swelling of Neuro-2A cells commenced once the pH in the medium was lowered to 6.8 or below. From this level downward, cell swelling was a function of the severity of acidosis and duration of exposure. For example, lactacidosis of pH 6.8 or 5.6 lasting 90 min led to an increase in cell volume to 109.5% or 159.6% of normal, respectively. Viability of the neuronal cells was 85% under control conditions. It remained in this range down to pH 6.2. At pH 5.6, however, cell viability decreased in a time-dependent fashion. At 90 min, only 48.9% of the neuronal cells were viable at pH 5.6. The swelling response and impairment of viability of the neuronal cells was compared with that of C6 glioma cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A novel NADH-dependent carbonyl reductase with an extremely broad substrate range from Candida parapsilosis: purification and characterization.

A novel oxidoreductase catalyzing the NADH-dependent reduction of a variety of carbonyl compounds, especially keto esters, was found in Candida parapsilosis DSM 70125. The enzyme was purified by fractional poly(ethylene glycol) precipitation, anion exchange, and affinity chromatography. The enzyme was enriched about 3100-fold and appeared to be homogeneous as judged by native and sodium dodecyl sulfate gel electrophoresis. The carbonyl reductase from C. parapsilosis is a dimeric enzyme with an apparent molecular mass of about 135 kDa. Important properties concerning the application of the enzyme are the relatively broad pH optimum between pH 6.5 and 9.0, temperature optimum between 36 and 42 degrees C, and good stability. Besides keto esters, the new enzyme reduces other aliphatic, aromatic, and cyclic ketones, as well as aldehydes and ketoacetals with high reaction rates. 4-Halo-3-hydroxybutanoates, which are promising chiral intermediates for the chemical synthesis of L-carnitine, alkaloids and pharmaceuticals, are now accessible by enzymatic reduction, as well as several phenyl-ethanol derivatives, which are important for the synthesis of pharmaceuticals and agrochemicals. The preparative applicability of the enzyme was demonstrated in a coupled enzyme system with regeneration of coenzyme. Methyl 3-oxobutanoate was converted into methyl (S)-(+)-3-hydroxybutanoate (98.5% ee), a versatile chiral building block for the synthesis of pheromones and different antibiotics.

Acetoacetates↗
PubMed1993

Linkage mapping of the Aldo-2, Pax-5, Ambp, and D4h9S3E loci on mouse chromosome 4 in the region of homology with human chromosome 9.

The genes for aldolase-B (ALDOB), the alpha 1-microglobulin/bikunin precursor (AMBP), the paired box gene PAX5, and the anonymous DNA marker D9S3 map to human chromosome 9 (HSA9). We have set out to map the mouse homologues of each of these genes. The mouse genes for Pax-5 and Ambp previously have been shown to map to MMU4. We have used an interspecific backcross to confirm these localizations and to map the mouse homologues of ALDOB (Aldo-2) and D9S3 (D4H9S3E) to the same chromosome. These genes were mapped with respect to the four anchor loci for MMU4. In addition, the panel of backcross DNAs had previously been typed for delta-amino levulinate dehydratase (Lv), orosomucoid-1 (Orm-1), and hexabrachion (Hxb), the human homologues of which map to HSA9q. The recombination distances +/- the standard error between each pair of loci are D4Nds4-1.6 +/- 1.1-D4H9S3E-4.0 +/- 1.7-Galt-0.8 +/- 0.8-Pax-5-4.8 +/- 1.9-Aldo-2-6.3 +/- 2.2-(Lv, Orm-1, Ambp)-1.6 +/- 1.1-Hxb-4.0 +/- 1.7-Tyrp-1-4.8 +/- 1.9-Ifa. The data from this study have extended the known region of conserved synteny between human chromosome 9 and mouse chromosome 4.

Alpha-Globulins↗
PubMed1993

[Cardiac pacemakers and implantable cardioverter-defibrillators in the perioperative phase].

Recent developments have changed the techniques and indications for different methods of temporary cardiac pacing. Temporary transvenous pacing involves endocardial right ventricular stimulation by a bipolar electrode, introduced directly via a vein, or through a "paceport" pulmonary artery catheter. A "multipurpose" pulmonary artery catheter permits both atrial and ventricular sensing and pacing. Noninvasive transcutaneous cardiac pacing is safe, fast, and easily applicable. However, pain and discomfort from cutaneous nerve or muscle stimulation may be intolerable for unsedated patients. Transoesophageal cardiac pacing is usually successful only for atrial stimulation, e.g., in sinus node bradycardia, but is not indicated in patients with impaired AV-conduction. In patients with implanted pacemakers, temporary cardiac pacing can both impair or improve the haemodynamic situation. Implanted pacemakers should always be checked following surgery involving electrocautery. Preoperatively, rate-responsive pacemakers should be re-programmed so as to avoid activation of the rate-responsive function. Automatic implantable cardioverter-defibrillators should be deactivated to avoid delivery of inappropriate shocks. In patients with implanted epicardial patch electrodes, transthoracic defibrillation can be difficult with routine defibrillation protocols and may require positioning of the paddles on the lateral chest wall. However, emergency noninvasive transcutaneous cardiac pacing is possible in such patients with normal thresholds.

Arrhythmias, Cardiac↗
PubMed1993

[The role of mixed venous oxygen saturation in perioperative monitoring and therapy. A critical stock taking].

Since mixed venous oxygen saturation (SvO2) depends on O2-supply and O2-consumption, its measurement is said to indicate tissue O2-balance and to be suitable for ensuring tissue oxygenation in critically ill patients. Blood for SvO2 determinations should be drawn exclusively from the pulmonary artery, because mixing of systemic venous blood is incomplete in the right atrium and ventricle. SvO2 can be determined in vitro and in vivo. Current in vivo techniques determine oxygen saturation from the relation between light emitted into the blood stream and that reflected from blood cells, the use of 3 instead of 2 wavelengths greatly improving the accuracy of the method. For reasonable interpretation of SvO2 it is necessary to consider the concentration of haemoglobin and its derivatives, shifts of the O2-dissociation curve, intracardiac left-to-right shunts, and systemic arteriovenous shunts. Disturbances of macrocirculation (e.g. vascular surgery) and microcirculation (e.g. sepsis) also impair the diagnostic value of SvO2 determinations. The critical value of SvO2 appears to depend on the prevailing disease. Patients with chronically impaired O2 transport appear to tolerate very low SvO2 values better than acutely ill patients, presumably due to adaptive changes in the former group. Central venous oxygen saturation may indicate directional changes of the SvO2, but does not estimate the real SvO2-value. The hypothesis that continuous SvO2 measurements improve prognosis or lower treatment costs has not yet been confirmed. Measurements of mixed venous oxygen saturation may improve monitoring and treatment of critically ill patients in selected cases; however, these measurements are not suitable to indicate reliably the status of tissue oxygenation under all conditions.

Humans↗
PubMed1993

Evolving experience with radical prostatectomy.

Thirty-six radical prostatectomies were performed over an 8-year period; 25 suitable patients (70%) presented with symptoms of bladder outflow obstruction. In 15 cases (44%), initial digital rectal examination was not indicative of malignancy. The primary tumour was understaged pre-operatively in 17 patients (48%). In 14 cases (41%) the pre-operative biopsy grade was different from the grade assigned to the tumour following radical prostatectomy. Radical prostatectomy is being performed with increasing frequency: trends in morbidity have been identified.

Adult↗
PubMed1993

Ureaplasma urealyticum in the cerebrospinal fluid of a premature infant.

A premature infant, born at 28 weeks' gestation, was found to be colonized with Ureaplasma urealyticum and developed intraventricular hemorrhage and progressive hydrocephalus during the first weeks of life. The organism was isolated from the infant's cerebrospinal fluid in the absence of marked cerebrospinal fluid pleocytosis, but meningitis was suspected on the basis of low glucose and high protein content. Since this organism was resistant to erythromycin by clinical criteria, the infant was treated with chloramphenicol for 20 days. Cerebrospinal fluid sterilization was demonstrated; hydrocephalus, however, was persistent and made intraventricular shunt placement necessary.

Chloramphenicol↗
PubMed1993

Analysis of transient-evoked otoacoustic emissions in normal-hearing and hearing-impaired ears.

Transient-evoked otoacoustic emissions (TEOAEs) were measured in 113 normal-hearing and hearing-impaired ears to examine repeatability within a test session, which TEOAE parameter (level, TEOAE level-to-noise or reproducibility) best identified hearing loss and if the TEOAE separated into frequency-specific bands identified hearing loss in a corresponding frequency region. TEOAEs and stimulus levels were found to be very repeatable. For broadband TEOAEs, TEOAE level, TEOAE-to-noise, and % reproducibility were found to identify hearing loss equally well, based on measurement of the area underlying relative operator characteristic curves. Analysis for frequency-specific bands showed that separation of normal-hearing and hearing-impaired ears depended on frequency, with best identification at 2000 and 4000 Hz, identification at 1000 Hz slightly worse, and virtually no separation between normal-hearing and hearing-impaired ears at 500 Hz. Again, all three parameters were essentially equal in identifying hearing loss. Subjective evaluations of presence or absence of TEOAEs was highly correlated between two judges, with good agreement for TEOAEs at 1000, 2000, and 4000 Hz. The findings from this study suggest that TEOAEs will be valuable for clinical use because of their repeatability and identification of hearing-impaired ears.

Acoustic Stimulation↗