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Biomedical subjects

R Weller

Publications and source records attributed to R Weller.

At least 91 records · Page 5Linked to original sources
PubMed1989

Quantification of amplitude images of gated radionuclide heart studies: a new universal method.

Absolute quantification in nuclear medicine is difficult because of the individual shape, size, and position of human organs. In this study, a general data processing procedure is presented that allows inter-individual comparison and definition of normal count density pattern of unevenly shaped scintigraphic structures. This new method is demonstrated on Fourier amplitude images of gated heart studies. The information contained in the original irregularly shaped left ventricular amplitude scans was transformed into a standard sized circle by interpolating the radiant profiles of varying length from the original left ventricular ROI into the radii of the standard circle using 720, 360, 180, and 72 sampling angles. Retransformation of the individual left ventricular amplitude image from the standard circle area is feasible with only approximately 1% error with the 180, 360, or 720 sampling steps. As a first application of this new method 20 normal amplitude studies were transferred into the standard circle, which allowed the definition of a statistically normal reference image against which individual left ventricular amplitude images may be compared for documenting areas of significantly depressed amplitudes quantitatively. This simple and unique approach may be applied to most organ-related scans such as brain, kidneys, lung, and liver both in planar and tomographic studies to first create a normal reference image and second, to quantify the significance of locally increased or decreased activity in routine scans automatically.

Heart↗
PubMed1989

[Quantification of the myocardial scar with technetium-99m-isonitrile (MIBI) in emission computerized tomography (SPECT)--comparison with serial creatine kinase determinations and radionuclide ventriculography].

Estimation of the size of myocardial infarction is of major interest for clinical patient management and a simple and reliable method is still searched for. In this study the potential of the new myocardial perfusion tracer, Technetium-99m (Tc-99m) methoxy-isobutyl-isonitril (MIBI) combined with emission computertomography (SPECT), is tested vs. the standard procedures of serial plasma creatine kinase (CK) measurements and radionuclide ventriculography (RNV). In 10 patients with first myocardial infarction, integral values for CK were obtained during the acute phase. Following three weeks of uncomplicated recovery the patient was referred for both types of myocardial imaging within four days. 370 MBq Tc-99m-MIBI were injected with the patient supine and at rest. One hour later SPECT acquisition commenced. The reconstructed slices were rearranged to long and short axes slices, which served to calculate a functional "scar image" in polar coordinates. The color-coded areas of significantly reduced tracer uptake were expressed in percent of the total myocardial area. RNV was performed with the patient supine and at rest, the left anterior oblique angle being optimized for septum visualization. Infarct localizations were antero-apical (three), anterolateral (two), postero-lateral (one), and posterior (four).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Differentiation between infarction and cardiomyopathy in left bundle branch block by parametric radionuclide imaging.

In LBBB the diagnosis of the underlying disease, i.e. infarction (MI) or cardiomyopathy (CMP), is still a challenge. In this study, the usefulness of radionuclide ventriculography (RNV) for solving this problem noninvasively was tested. The hypothesis was that quantitation of the space-time sequence of left ventricular (LV) contraction by Fourier analysis may differentiate among MI, CMP, and LBBB-specific wall motion abnormalities (WMA). Forty-seven patients (pts) with LBBB were divided into 3 groups: 1) 20 pts with MI, 2) 7 pts with CMP, 3) 20 pts without MI or CMP. Regional parametric amplitude and phase data of eight LV sectors were calculated and expressed in standard deviation units (SDU) of normal. Out of the many regional data only the values of the mean amplitude and the standard deviation of the mean phase shift showed high discriminative power for separating the three groups, with an average squared canonic correlation of 0.5 and a Wilks lambda of 0.22, respectively. In other words, 17 of 20 pts in group 1, 6 of 7 pts in group 2, and 19 of 20 pts in group 3 were truly diagnosed by RNV alone. Such a separation also seems reasonable physiologically, since the mean amplitude reflects global left ventricular function and standard deviation of phase is a measure of time homogeneity of contraction. Furthermore, there was a significant septal phase delay of -4.92 +/- 5.3 SDU in 15 pts with septal MI compared to group 3 pts, who had a subtle premature septal motion of +0.75 +/- 2.64 SDU, whereas the septal amplitude was not different and slightly decreased in both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1981

[Haemodynamics of blood supply to the pulmonary or body circulation via a patent ductus arteriosus in infants (author's transl)].

To control the cardiopulmonary functioning of high risk newborn with congenital heart defects the authors apply computergenerated recording of vital parameters predominantly measured by non-invasive methods. It was found that periodic variations of the arterial partial oxygen pressure occur with occlusion of the outflow from both the right and the left ventricle, associated with patent ductus arteriosus. The authors interpret these periodic variations as intermittent contractions of the arterial duct. The pathophysiology of this phenomenon is discussed.

Blood Circulation↗
PubMed1981

[Assessment of left ventricular regional function by means of radioactive isotopes (author's transl)].

Extensive analysis of heart function by scintigraphy yields global parameters of ventricular volumes and their changes during the heart cycle (ejection fraction, enddiastolic and endsystolic volumes, velocity of contraction and relaxation). Additionally, information regarding localized disorders of wall motion may be obtained in a qualitative and quantitative manner by the parameters "phase" and "amplitude". These parameters can be computed from regional time-activity curves by Fourier analysis. The radionuclide ventriculogram at rest is suitable for the detection and follow-up of asynergies caused by acute and chronic infarction. In can also be used as a method of distinguishing between reversible and irreversible asynergy by therapeutical intervention (intervention ventriculography). Abnormalities of regional wall motion which develop during exercise may indicate hemodynamically relevant coronary artery stenoses.

Cardiac Output↗
PubMed1972

[Xyphodynia].

Explore the source record for details and available documents.

Adult↗
PubMedDate not supplied

Detection of nitric oxide and nitric oxide synthases in psoriasis.

Biopsies from psoriasis lesions and clinically uninvolved skin of eight patients and five normal subjects were studied by immunocytochemistry with computerized image analysis for the presence of endothelial, neuronal and inducible isoforms of nitric oxide synthase. Endothelial nitric oxide synthase was expressed in the endothelium and weakly in some keratinoctyes. Its expression was not significantly different in psoriasis. Inducible nitric oxide synthase, however, was absent from normal skin but was significantly upregulated in psoriatic lesional skin, focally in keratinocytes but to the greatest extent in the papillary dermis and to a lesser extent in clinically uninvolved psoriatic skin. Inducible nitric oxide synthase staining was greatest in the more severe lesions and correlated with the inflammatory infiltrate (CD3-positive cells) and with keratinocyte proliferation (Ki-67-positive cells). In normal skin, neuronal nitric oxide synthase was expressed only in keratinocytes in the granular layer and eccrine sweat glands. However, in psoriasis and clinically uninvolved skin the neuronal form was present through all levels of the epidermis. Direct measurement of nitric oxide production from the skin surface revealed a tenfold increase in the lesions of 16 psoriatic patients compared with their nonlesional skin, and this nitric oxide production was inhibited by topical betamethasone.

Adult↗
PubMedDate not supplied

The visible animal project: a three-dimensional, digital database for high quality three-dimensional reconstructions.

The "Visible Animal Project" (VAP) is comprised of axial anatomic cryosections and corresponding CT and MR images of a mature dog. The digital database is used for the creation of three-dimensional computer graphics of canine anatomy. The technique of cryodissection is described in detail. The combining of the corresponding CT and MR images, and cryosections as well as the data processing for the creation of three-dimensional reconstructions is presented and examples are shown. For the first time a complete high-resolution three-dimensional database of a dog is available, which can be used as the base for further high quality three-dimensional reconstructions, similar to the "Visible Human Project" (VHP).

Anatomy, Cross-Sectional↗
PubMedDate not supplied

Pro- and anti-apoptotic effects of nitric oxide in irradiated keratinocytes: the role of superoxide.

Ultraviolet radiation (UV) induces apoptosis in keratinocytes by both p53- and death receptor-dependent pathways. It also generates free radicals in keratinocytes, including the synthesis of nitric oxide (NO) by constitutive and inducible NO synthases (NOS). NO has both pro- and anti-apoptotic effects. We wished to determine which of these was predominant in keratinocytes. Human CCD1106 keratinocytes were irradiated with UVB in the presence and absence of several NOS antagonists. Apoptosis was measured by flow cytometry with annexin V binding. NOS antagonism consistently altered UVB-induced apoptosis measured 18 h after irradiation. In 9 of 13 experiments, NOS antagonism increased apoptosis. However, in 4 of 13 experiments, NOS antagonism reduced apoptosis. We postulated that the variable effects of NO might be due to a critical balance between UVB-induced NO and superoxide production. We predicted that NO would be anti-apoptotic in the presence of low O(-)(2), but pro-apoptotic when NO combined with O(-)(2) to form peroxynitrite. Though superoxide dismutase reduced apoptosis after UVB, addition of peroxynitrite did not affect apoptosis. We conclude that NO released by UV irradiation is anti-apoptotic; however, the levels of O(-)(2) may be a determinant of NO action.

Animals↗