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Biomedical subjects

D Jonas

Publications and source records attributed to D Jonas.

At least 55 records · Page 3Linked to original sources
PubMed2000

Information giving can be painless.

Pain is an inevitable consequence following day surgery, but with effective regular pain relief minimal discomfort can be achieved. An information leaflet produced by a pain nurse specialist in collaboration with a multidisciplinary team ensures that comprehensible and non-contradictory information is given to parents. With the increased trend towards paediatric day surgery parents are significant contributors to their child's care in the postoperative period. Written information on pain relief after discharge can help parents make decisions about their child's pain management.

Adult↗
PubMed1999

Disease activity related catecholamine response of lymphocytes from patients with rheumatoid arthritis.

In patients with chronic rheumatic diseases, a decreased density of beta 2-adrenergic receptors (beta 2R) on peripheral blood mononuclear cells (PBMC) could be demonstrated negatively correlating with various disease activity parameters. The aim of the present study was to determine the impact of this decrease on catecholamine response of PBMC from patients with rheumatoid arthritis (RA) in vitro. PBMC from 17 patients with RA and 6 healthy blood donors (HD) were investigated. The effects of epinephrine (E) and norepinephrine (NE) on PBMC proliferation were studied using cells activated with phytohemagglutinin (PHA) and monoclonal anti-CD3-antibodies (OKT3), respectively. The results revealed that lymphocytes of patients with RA showed a significantly reduced influence of catecholamines on PBMC function. In RA patients with high disease activity only, a shift to alpha 1-adrenergic-mediated catecholamine effects upon PBMC reactivity could be observed. The study demonstrates the intricate relationship between PBMC reactivity and catecholamine effects that is mediated via alpha- and beta-adrenergic receptors due to disease activity. In this respect the altered catecholamine response of PBMC from patients with RA may contribute to the pathogenic process of RA.

Adrenergic alpha-Agonists↗
PubMed1999

Evaluation of the mecA femB duplex polymerase chain reaction for detection of methicillin-resistant Staphylococcus aureus.

This study systematically evaluated a recently described duplex polymerase chain reaction test for methicillin-resistant Staphylococcus aureus with 25 different German epidemic strains of methicillin-resistant Staphylococcus aureus and 66 staphylococci other than methicillin-resistant Staphylococcus aureus, including 17 different coagulase-negative staphylococcal species and subspecies, that were either oxacillin susceptible or oxacillin resistant. The results were compared with those of conventional cultural identification and susceptibility testing. Of the 91 isolates tested, all 25 confirmed strains of methicillin-resistant Staphylococcus aureus were identified correctly. None of the remaining strains of methicillin-susceptible Staphylococcus aureus was misidentified as methicillin-resistant Staphylococcus aureus. It was concluded that the duplex polymerase chain reaction appears to offer a time-saving and accurate method of detection of methicillin-resistant Staphylococcus aureus.

Bacterial Proteins↗
PubMed1999

Reduced catecholamine response of lymphocytes from patients with rheumatoid arthritis.

Catecholamines modulate lymphocyte function via stimulation of beta2-adrenergic receptors (beta2R). Previous investigations revealed a decreased density of beta2R on peripheral blood mononuclear cells (PBMC) in patients with chronic rheumatic diseases. Aim of the present study was to determine the impact of this decrease on catecholamine response of PBMC from patients with rheumatoid arthritis (RA) in vitro. PBMC from 17 patients with RA and 12 healthy blood donors (HD) were investigated. Beta2R were determined by a radioligand binding assay. The effects of epinephrine (E) and norepinephrine (NE) on PBMC proliferation were studied using cells activated with pokeweed mitogen (PWM) and monoclonal anti-CD3-antibodies (OKT3), respectively. In parallel, alpha1- or beta-receptor antagonist were added to the culture to determine the specificity of the catecholaminergic effects. The results showed that depending on the stimulus and the catecholamine concentration employed E and NE exert inhibitory (OKT3) or stimulatory signals (PWM) on lymphocyte proliferation. Inhibitory effects could be abolished by adding beta-antagonist, while stimulatory signals were diminished after addition of alpha1- of beta-antagonist. Patients with RA showed a significantly reduced density of beta2R compared to HD paralleled by a significantly reduced influence of catecholamines on lymphocyte function. The study demonstrates the intricate relationship between PBMC reactivity and catecholamine effects that are mediated via alpha1- and beta-adrenergic receptors. In this respect the reduced catecholamine response of PBMC from RA patients may contribute to the pathogenic process of RA.

Adrenergic alpha-Antagonists↗
PubMed1999

Influence of different types of surface electrodes on amplitude, area and duration of the compound muscle action potential.

OBJECTIVES: The aim of this study was to evaluate if the type of surface electrode (disposable/non-disposable, fixed/variable inter-electrode distances, different surface structure and size of recording area) influences the compound muscle action potential (CMAP) values of baseline-to-peak and peak-to-peak amplitude and corresponding areas and duration. METHODS: We investigated a total of 72 CMAPs of the abductor digiti minimi and the tibial anterior muscle of 18 healthy persons using 7 different types of electrodes in each muscle. RESULTS: There was no significant difference of CMAP values between the electrodes which had a variable inter-electrode distance. A significant difference of all CMAP values was observed when these electrodes were compared with a bar-electrode with a fixed inter-electrode distance (P<0.001). There was no correlation between recording area of the electrodes and the absolute CMAP values. Only the differences of CMAP values between each electrode and a defined electrode in each subject revealed a significant correlation between the size of recording area and these differences of CMAP values. CONCLUSION: To avoid false results in motor neurography only electrodes with variable distances between the recording pairs should be used. Using those electrodes and following standardized measuring conditions, CMAP values can be compared even if they are measured in different laboratories and at different occasions.

Action Potentials↗
PubMed1998

Distractibility, circadian arousal, and aging: a boundary condition?

Two studies assessed the presence of a synchrony effect between peak circadian arousal and time of testing for both older and younger adults. Participants performed a reading aloud task that included distracting words that were either present or absent and, if present, were either thematically related or unrelated to the target text. As well, the distracting material was presented in either spatially predictable or unpredictable locations. In each experiment, older and younger adults were tested at optimal versus nonoptimal times. Both experiments showed age differences in susceptibility to distraction, replicating earlier findings (e.g., M. C. Carlson, L. Hasher, R. T. Zacks, & S. L. Connelly, 1995). Neither showed differences due to time of testing, suggesting a boundary condition for cognitive disruptions associated with circadian arousal patterns.

Adolescent↗
PubMed1997

Loss of in vitro cytotoxicity of cisplatin after storage as stock solution in cell culture medium at various temperatures.

BACKGROUND: Cisplatin (cis-dichlorodiammineplatinum [II]) is one of the most potent and widely used cytotoxic drugs in cancer therapy. However, in vitro cytotoxicity assays often yield diverging results. Therefore, it is believed by many investigators that cisplatin is not effective in vitro. The authors investigated whether the experimental conditions used could be responsible for the diverging results. METHODS: In vitro cytotoxicity assays were performed using the original cisplatin solution as distributed by the manufacturer or a 5-fold dilution of this in cell culture medium after storage for 2 weeks or 1 month at various temperatures (room temperature, 4 degrees C, and -20 degrees C). RESULTS: The original solution of cisplatin retained the full cytotoxic potency for at least 1 month under all storage conditions tested. The highest loss of cytotoxicity resulted from storage of cisplatin in cell culture medium in which a >7-fold increase in the concentration that inhibits 50% occurred after 2 weeks' storage at room temperature. Solutions stored in culture medium at -20 degrees C retained full cytotoxic potency. CONCLUSIONS: Cisplatin is a potent cytotoxic drug in vitro when stored under appropriate conditions. These findings are of relevance for in vitro studies with cisplatin.

Antineoplastic Agents↗
PubMed1997

Fast T1 imaging of dual gel samples for diffusion measurements in NMR dosimetry gels.

Diffusion of iron is one of the major problems limiting the usefulness of NMR gel dosimetry. This was studied in dual gel samples using a 4.7T micro-imaging MR scanner and a fast T1 imaging sequence which allowed the acquisition of a 64 x 128 x 8 data sets (phase encoding x frequency encoding x number of inversion times) in less than 15 min. The procedure enabled us to obtain relative relaxation times for any region of interest within the sample. After the two differently doped gels were brought into contact in the dual gel samples (diameter 12 mm), the diffusion could be observed on subsequent images as a function of time. An inverse square root function was used to fit the change of 1/T1 across the junction between the two gel phases. A diffusion constant of 0.014 +/- 0.003 cm2/h was determined for Fe3+ in a typical dosimetry gel (1.5% agarose, 50 mM H2SO4). This could be lowered by adding a chelating agent such as xylenol orange to the gel. It was also found that diffusion was slower in gelatine gels, however these gels tended not to set properly when H2SO4 was added as required for NMR dosimetry. From the present results we propose that a gel consisting of 1.5% agarose (for stability), 3% gelatine and 0.1 mM xylenol orange (to combat diffusion and allow a visual evaluation) is a suitable base for NMR dosimetry gels. The use of a fast T1 imaging sequence reduces acquisition times and therefore the potential impact of diffusion.

Chelating Agents↗
PubMed1997

[The indication for cystoscopy in children].

The diagnostic procedures in children presenting urological symptoms, i.e. hematuria, recurrent urinary tract infections, disorders of the upper urinary tract or of the pattern of micturition include urinary sediment and bacterial culture, the investigation of red blood cell morphology, urinary electrolytes and osmolarity, ultrasound, i.v. pyelogram, cysturethrogram, combined uroflow and pelvic floor-EMG, MAG III-clearance and a urodynamic evaluation. In the rare situation of unclear symptoms that defy the non-invasive diagnostic procedures mentioned, a urethrocystoscopy can be advisable. A cystoscopy will be mandatory in endoscopic therapy or when operative interventions are planned.

Child↗