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Biomedical subjects

B Jung

Publications and source records attributed to B Jung.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Psychiatrically relevant side effects of non-psychopharmacological pharmacotherapy].

We briefly review the possibilities of side effects caused by therapy with drugs other than psychotropic agents. These complications are mainly depressive/manic, paranoid-hallucinatoric/deliriant or anxiety/panic syndromes. Especially elderly patients and patients with multiple diseases are the preferred group with these side effects, because they are most likely to show a disturbance of blood-brain barrier and renal clearance. We will discuss the psychiatrically meaningful side effects of frequently used drugs, and we will present a concept of how to reduce such unwanted side effects.

Aged↗
PubMed1994

Anal endosonography in healthy subjects and patients with idiopathic fecal incontinence.

PURPOSE: This study investigates the normal ultrasonographic morphology of pelvic floor striated muscle and evaluates whether there are differences between males and females and between healthy subjects and patients with idiopathic fecal incontinence. METHODS: Manometric and ultrasonographic studies of the anal canal were performed in 30 healthy volunteers and in 26 patients with idiopathic fecal incontinence. Verification of ultrasonographic findings was obtained by studying anatomic preparations. RESULTS: Ultrasonography reliably identified the internal and external anal sphincter and frequently visualized neighboring structures. In addition, it detected muscular structures that have not clearly been described previously. However, differences in external sphincter function between males and females and between healthy subjects and incontinent patients were not reflected by alterations in muscle thickness. CONCLUSIONS: Endosonography of the anal canal clearly delineates muscular structures and may even visualize structures that have been previously incompletely defined. However, it remains to be shown that differences in certain muscular functions have a morphologic correlate that can be detected by endosonography.

Adult↗
PubMed1994

Fieldwork education: a shared supervision model.

This paper describes how McMaster University, Department of Occupational Therapy implemented a shared supervision model during an adult physical health block clinical placement, in two fieldwork settings in Hamilton. Five students were assigned to each of the clinical facilities and spent time with the group supervisors and clinical preceptors to meet their learning needs. The objectives, implementation process, training and orientation process, learning and evaluation process, and outcome of this project are discussed. The shared supervision model appears to be a viable alternative supervision model in fieldwork education.

Clinical Clerkship↗
PubMed1994

Oncostatin-M is an autocrine growth factor in Kaposi's sarcoma.

Oncostatin-M is a cytokine produced by macrophages and activated T lymphocytes that has recently been shown to be a mitogen for AIDS-related Kaposi's sarcoma (KS)-derived spindle cells. The significance of oncostatin-M production in AIDS-related KS in vivo, however, remains unknown. In this study we wanted to determine whether oncostatin-M is expressed in vivo in patients with HIV-I-related KS, define the cell types that express this cytokine, and compared with the control tissues from HIV-I-negative individuals. A second objective of our study was to define the expression of oncostatin-M in AIDS-KS-derived spindle cell isolates cultured in vitro and to determine whether oncostatin-M is an autocrine growth factor for these KS cells. We have determined that oncostatin-M is not expressed in any of the several organs examined in control cases, whereas the tumor tissue obtained from the skin biopsies of HIV-I-infected cases with KS displayed oncostatin-M expression in the spindle cell components of the tumor, as well as the cells lining the vascular structures, smooth muscle cells lining the eccrine sweat glands, and the epidermal layers of the skin. Furthermore, uninvolved skin of patients with HIV-related KS express oncostatin-M in the cells lining normal vessels. The mRNA polymerase chain reaction analysis confirmed findings in the primary tissues and showed expression in all of the AIDS-KS-derived spindle cell isolates examined. We have also shown with the use of oncostatin-M-specific antisense oligodeoxynucleotides that KS cell proliferation is inhibited, which correlated with a more precipitous decline in the production of interleukin-6 by these cells. We conclude that oncostatin-M is only expressed in the skin and KS tumor of HIV-I-infected individuals. Furthermore, we provide evidence that oncostatin-M is an autocrine growth factor for KS.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Properties of the phase-alternating phase-shift (PHAPS) multiple spin-echo protocol in MRI: a study of the effects of imperfect RF pulses.

The effects of imperfect radiofrequency (RF) pulses on the echo amplitudes from the Carr-Purcell (CP), Carr-Purcell-Meiboom-Gill (CPMG), and the PHase-Alternating Phase-Shift (PHAPS; combination of CP and CPMG) multiple spin-echo schemes were studied. Properties of the PHAPS scheme for transverse relaxation time measurements was emphasized. Numerical simulations on non-relaxing spin systems were performed to assess the properties of selective (damped sinc shaped) and nonselective refocusing pulses in terms of effective spatial selectivity and generation of secondary echo signal. Analytical solutions of the Bloch equations were applied to study the generation and propagation of stimulated echo signal caused by nonideal 180 degrees phase reversals, and the results were used to analyse the numerical simulations in terms of primary and stimulated echo components. Finally, the simulated echo train patterns from the different MSE schemes were compared with MR imaging measurements. It was found that the underestimation of T2 values by the PHAPS protocol with selective refocusing pulses is mainly an effect of an "artificial" echo amplitude decay in the CP scheme, while the CPMG scheme produces a typical even-odd echo pattern (different from corresponding echo patterns in conventional high resolution NMR). Both effects are related to the flip angle error and phase dispersion along the slice selection direction from selective RF pulses, and are not significantly influenced by stimulated echo interference for nonrelaxing spin systems. However, the presence of stimulated echoes at the time of the primary echoes implies a dependence on T1 of the PHAPS echo amplitudes. In the CPMG protocol, different gradient schemes have been implemented to defocus stimulated echoes. However, the results indicate that there exists stimulated components that will not be affected by such gradients, and that the optimization of the RF refocusing pulses then remain the main objective.

Artifacts↗
PubMed1993

Clinical effects of biologic response modifiers.

The clinical use of the biologic response modifiers filgrastim, sargramostim, and regramostim is reviewed. All circulating blood cells are derived from totipotent hematopoietic stem cells. Various biologic response modifiers, including lymphokines and colony-stimulating factors, regulate and activate the lymphoid and myeloid cells of the blood. One of the more important types of blood cell for fighting infection is the neutrophil. Patients with low neutrophil concentrations are at high risk of developing neutropenic fevers and infections. The colony-stimulating factors filgrastim, sargramostim, and regramostim increase the production of circulating neutrophils, and this action is clinically useful in patients undergoing myelosuppressive antineoplastic therapy or bone marrow transplantation and in patients with the acquired immunodeficiency syndrome. Clinical studies of these agents in comparison with antimicrobial prophylaxis or placebo have shown a decreased rate of neutropenic-associated hospitalizations and infections. These agents are also under study for dose intensification of antineoplastics in patients with various solid tumors and for augmenting patient responses to antimicrobial therapy in situations where there is high risk of morbidity and mortality. Sargramostim and regramostim are both granulocyte-macrophage colony-stimulating factors that differ in their degree of glycosylation and source of production, and at high doses they can cause life-threatening adverse effects because they stimulate the production of a broad range of leukocytes. Filgrastim, which stimulates only the production of neutrophils, has been better tolerated, especially at higher doses. Biologic response modifiers hold much promise for improving therapy of certain clinical conditions by decreasing myelosuppressive complications and enhancing responses to other drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1990

Effectiveness of an antibiotic cost containment measure.

University Hospital, University of British Columbia (UBC) Site, a 600-bed teaching hospital in Vancouver, British Columbia, adopted several cost containment measures on August 2, 1988 in an attempt to limit the rise in antibiotic expenditures. One cost containment measure involved extending the dosing intervals of cefazolin, clindamycin and metronidazole by a pharmacy-based automatic dosing interval interchange. Cefazolin and clindamycin orders were changed to an every eight-hour dosing schedule, and metronidazole orders to an every 12-hour schedule. Data were retrospectively collected and tabulated from August 1987 to February 1988 (pre-implementation or PRE period) and August 1988 to February 1989 (post-implementation or POST period). During the POST period, the mean doses per course were significantly less for metronidazole. Estimated cost savings from the measure was $7,300 for the seven-month POST period. Annualized, the expected savings would be $12,600, which is 4.4% of 1988/1989 total antibiotic expenditures. This cost containment strategy achieved its goal of effective cost savings for University Hospital, UBC Site. Although a small reduction in total drug budget was seen, this study suggests that savings can be achieved through this cost containment measure.

Anti-Bacterial Agents↗
PubMed1989

Resolution of biexponential transverse relaxation in magnetic resonance imaging.

The accuracy in measurements of mono- and biexponential transverse relaxation processes with an MRI unit (0.5 T) was studied with a binary phantom. Comparison with spectrometer measurements (0.5 T) demonstrated that the imager underestimated the T2 values for monoexponential processes. Numerical resolution of biexponential processes also yielded underestimated relaxation times, but the resolution of a slow, constant component from faster components was relatively precise and consistent, provided the T2 ratio was above 2.5 in the T2 range 200-800 ms for a spin-echo sequence with 32 echoes. The effects of signal-averaging, strength of slice-selective gradient, single- versus multi-slice mode and repetition time were of little importance. In coronal slices a spurious biexponentiality occurred occasionally from monoexponential sources. The influence of stochastic noise was of minor importance compared to the effect of systematic noise.

Magnetic Resonance Imaging↗
PubMed1989

Comparison between electrophysiologic and morphologic changes in lead induced peripheral neuropathy in rats.

Compound nerve action potential (CNAP) of the mixed peripheral nerve is composed of A alpha beta, A delta, and C potentials. All components of CNAPs in the sciatic nerve were recorded by stimulating the tibial nerve of both control and lead-poisoned rats. Marked decrease of nerve conduction velocity and prolonged duration were found in A alpha beta and A delta fibers especially in large myelinated A alpha beta fibers. The amplitude decreased in A alpha beta potential, but the area did not change. In C potential produced by activation of unmyelinated fibers, nerve conduction velocity slightly decreased, but the amplitude and area did not significantly change. Pathologic correlates revealed prominent segmental demyelination with significant decrease of large myelinated fiber densities. Minimal axonal degeneration of unmyelinated fibers was present. We can conclude that electrophysiologic changes in the lead-poisoned rats correlate with pathologic changes in them.

Animals↗
PubMed1987

Delayed hypersensitivity responses in children after local cutaneous anesthesia.

The effect of cutaneous analgesia on delayed type hypersensitivity (DTH) reactions as challenged by injections in the skin was assessed by comparing a lidocaine/prilocaine mixture with placebo. Application of 5 g of the mixture 90 min before testing significantly (p less than 0.001) reduced pain but did not influence the DH-reactions as read after 48 hours. Based on these findings, DTH to several antigens were measured in 116 school children, aged 7-15 years. All the children were positive to either tetanus antigen, 7.5 Lf/ml (98% at 48 hours) or mumps test antigen (82%), while positivity to tuberculin 2 TU/ml and candida 1000 PNU/ml were only 11 and 62% respectively. Therefore, DTH tests in an adequately immunized population of children can be limited to two antigens. Application of cutaneous analgesia is recommended as a routine procedure in DTH testing in young children.

Adolescent↗
PubMed1986

Improved formulae for signal amplitudes in repeated NMR sequences: applications in NMR imaging.

An improved formalism describing the dependence of the signal strength on relaxation times and spin densities in pulsed nuclear magnetic resonance experiments is presented. It is especially applicable to repetitive experiments such as occur in imaging applications. Essentially, it includes long-time spin coherence effects not considered in the algorithms usually adopted. Also, some generalizations of classical concepts are made. Validity criteria are studied using numerical simulations. The algorithm assumes a relatively inhomogeneous main magnetic field, but the computer simulations indicate that the inhomogeneity normally present in magnetic resonance imagers is sufficient. The simulations also indicate that the field gradient pulses applied in the spatial encoding procedure do not necessarily interfere seriously with the validity of the formulae, but complicate the choice of optimal formula and may in some circumstances prevent the spin system from reaching a steady state.

Algorithms↗
PubMed1986

T1, T2, and relative proton density at 0.35 T for spleen, liver, adipose tissue, and vertebral body: normal values.

An MRI installation (Magnetom, Siemens, software version B1 of NUMARIS) working at 0.35 T was used to estimate T1, T2, and relative proton density in the spleen, liver, adipose tissue, and vertebral body in 14 healthy volunteers. Two double-echo sequences were applied for all subjects: TR = 500 ms, TE1 = 35 and TE2 = 70 ms; and TR = 1600 ms, TE1 = 35 and TE2 = 70 ms. The images were sampled in regions of interest and appropriate relaxation expressions fitted to the ROI data yielding relaxation parameters and relative proton densities. Relaxation expressions, included in standard software (Siemens), were compared to more elaborate functions, developed in parallel to this study. The latter were found more appropriate, especially for high T1 values, and gave the following mean values for the four tissues (estimated uncertainty of mean in parentheses) T1 (ms) 915(36), 428(5), 261(7), and 501(11); T2 (ms) 79.7(8.8), 51.0(0.2), 59.8(1.0), and 64.7(0.8); and corresponding relative proton density (rho, arbitrary units) 2088(136), 2182(10), 2915(49), and 2136(21). The uncertainty in the values was estimated in the fitting procedure and does not include systematic errors. The relative noise in the ROIs was about 9% and the reproducibility of the ROI mean values about 8%.

Adipose Tissue↗
PubMed1986

Selective properties of trains of real and complex RF micropulses in slice-selective spin-echo MRI.

The spin nutation properties of frequency selective (space selective in combination with a magnetic field gradient) trains of radiofrequency micropulses were studied in a numeric model. Two cases were considered, one simulating the 90 degrees excitation pulse in spin-echo MRI, the other the 180 degrees spin inversion pulse. Image reconstruction according to the 2-D Fourier transform technique requests that the effect of the 180 degree pulse is independent of the initial phase of the spin vector relative to the radiofrequency field. It was found that with a train of phase-stable radiofrequency micropulses with an envelope of the traditional 'sinc' type the result of the spin inversion pulse was depending on the initial phase whereas this was not the case for a train of phase-shifted (complex) micropulses. The complex train of radiofrequency micropulses also had better selective properties both for excitation and spin inversion than the real one.

Electron Spin Resonance Spectroscopy↗
PubMed1986

Subtraction in magnetic resonance imaging.

Subtraction of images recorded with multiple echo, spin echo (SE) techniques was performed in phantom and clinical studies of patients with pituitary adenomas and gliomas. The tissue differentiation was enhanced in the subtracted images.

Adenoma↗
PubMed1986

Cerebrospinal fluid flow studied with gated magnetic resonance imaging during the various parts of the cardiac cycle.

The pulsatile movement of cerebrospinal fluid (CSF) through the Sylvian aqueduct has been studied in two normal volunteers. A standard magnetic resonance scanner was used as well as a routine spin echo sequence. Series of ECG-gated axial images were obtained perpendicular to the long axis of the Sylvian aqueduct. Previously it has been demonstrated by flow phantom experiments that the phase information can be used to obtain a linear relation between phase and flow velocity. By multiplying the CSF flow velocity by the cross-sectional area of the aqueduct of Sylvius obtained in each image, the CSF flow variation during the cardiac cycle could be demonstrated and measured.

Cerebrospinal Fluid↗
PubMed1985

Affinity and efficacy of racemic, (+)-, and (-)-methacholine in muscarinic inhibition of [3H]-noradrenaline release.

The right postganglionic sympathetic nerves of rat isolated perfused hearts (previously loaded with [3H]-noradrenaline) were stimulated electrically with 10 trains of 10 pulses at 10 Hz. The inhibition by methacholine of stimulation-evoked [3H]-noradrenaline overflow into the perfusate (determined in the presence of corticosterone, desipramine, phentolamine, and propranolol) was taken as a measure for activation of presynaptic muscarinic receptors. The evoked [3H]-noradrenaline overflow was inhibited by (+)-, racemic, and (-)-methacholine in a reversible and concentration-dependent manner. The concentration causing 50% inhibition (IC50) was 0.1, 0.26, and 65 microM, respectively, resulting in an isomeric potency ratio IC50 (+)/IC50(-) of 650. The dissociation constant KA of the (+/-)- or (+)-methacholine-presynaptic receptor complex was determined after fractional receptor inactivation according to Furchgott & Bursztyn (1967) with phenoxybenzamine or propylbenzilylcholine mustard as irreversible antagonists of muscarinic receptors. KA for (-)-methacholine was estimated according to Mackay (1966). KA of (+)-, (+/-)-, and (-)-methacholine were 2.5, 4 and 440 microM, resulting in an isomeric affinity ratio KA (+)/KA(-) of 180. The discrepancy between the isomeric IC50 ratio and the isomeric KA ratio is explained by a higher intrinsic efficacy of the (+)-enantiomer compared to the (-)-enantiomer. Thus, (+)-methacholine has to occupy fewer receptors to induce a given inhibition of release than its antipode as revealed by a plot of fractional receptor occupancy vs response. The results show that, in the effector system of presynaptic muscarinic inhibition, methacholine enantiomers differ greatly not only in affinity for the receptor, but also to some extent in the efficiency of signal transmission, and both parameters contribute to the high isomeric potency ratio. The activity of the racemate is fully accounted for by the activity of the (+)-enantiomer.

Animals↗