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Biomedical subjects

S Yaffe

Publications and source records attributed to S Yaffe.

18 recordsLinked to original sources
PubMed1996

Brain SPECT imaging of neuropsychiatric disorders.

Brain imaging has become an integral part of the evaluation of neurological and psychiatric disorders. Functional imaging techniques, SPECT and PET, together with structural modalities, CT and MRI, are widely employed. Functional imaging studies are routinely used in the diagnostic workup of patients with well-characterized neurological disorders, such as epilepsy and brain tumors, and have a growing role in research on psychiatric disorders without known mechanisms such as depression and schizophrenia. Furthermore, many well-defined neurological disorders manifest prominent psychiatric symptomatology which may pose difficulties in differential diagnosis. This review addresses the current knowledge of SPECT findings in patients who present with psychiatric phenomena, associated with disorders at the interface of neurology and psychiatry.

Alzheimer Disease↗
PubMed1994

A measurement of pulmonary blood volume increase during systole in humans.

Pulmonary blood volume increase during systole was measured in patients by analysing chest images obtained during ECG gated radionuclide angiography examination. The difference in the total radiation counts between systole and diastole in regions of interest, which included the lungs and the left ventricle, was measured and the relative pulmonary systolic blood volume increase (SBVI)-the ratio between the pulmonary SBVI and the cardiac stroke volume-was calculated. The relative pulmonary SBVI, which is a measure for the compliance of the pulmonary blood vessels, was found to be 0.26-0.85, and the average value was 0.57 +/- 0.15. The relative pulmonary SBVI was inversely correlated with the patient age (r = 0.27, p < 0.05) and with the left ventricular ejection fraction and stroke volume (r = 0.36, p < 0.01) due to decreased arterial compliance for older patients and for increased pulmonary blood volume respectively. The correlation coefficients were not high, indicating that the compliance of the patients is determined mainly by other individual factors. Radionuclide plethysmography enables qualitative assessment of pulmonary arterial compliance.

Aging↗
PubMed1994

Gallbladder visualization with In-111 labeled octreotide.

In-111 DTPA octreotide, a labeled somatostatin analog, was reported to be superior to I-123 octreotide for detection of somatostatin-receptor-bearing tumors because of longer half-life and better labeling characteristics. In addition, renal rather than hepatobiliary clearance decreases intestinal interference and greatly reduces accumulation of the tracer in the gallbladder. Using the In-111 labeled octreotide, the authors noted distinct gallbladder visualization in one patient with an insulinoma who was studied following an overnight fast. In two additional patients scanned in the fasting state gallbladder uptake was also demonstrated. In all 3 patients, this uptake disappeared following a meal. The authors conclude that when using this imaging modality, abdominal scans should not be performed in the fasting state. Furthermore, if significant uptake is demonstrated in the gallbladder area, imaging should be repeated several hours later, following a fatty meal. Both false-positive and false-negative findings of pathologic uptake in this area will thus be avoided.

False Negative Reactions↗
PubMed1993

Registration and display of multimodal images: applications in the extracranial head and neck region.

Image registration is a correlation procedure that allows the matching of images obtained by different imaging modalities, both structural and functional. Once registered, they can be combined in a single "fused" image. This technique can be used to improve the interpretation and the quantification of relatively low resolution images obtained in nuclear medicine or to achieve a better diagnosis and treatment planning when high resolution anatomical images are registered. Matching images obtained by different imaging modalities is a major challenge and the various registration techniques are briefly described. The extracranial head and neck region is a challenging field for image registration. A preliminary retrospective experience is presented emphasizing the technique feasibility in a routine clinical context. 2-D and 3-D approaches were used. The requirements for transferring registration technology from the image processing laboratory to clinical practice are discussed, and the contribution of this method to medical interdisciplinary communication is emphasized.

Aged↗
PubMed1992

ECG gated radionuclide plethysmography--a method for the assessment of pulmonary systolic blood volume increase.

During cardiac systole the stroke volume of blood which is ejected from the right ventricle increases the pulmonary blood volume. This systolic pulmonary blood volume increase is measured by using ECG gated chest scintigrams obtained with 99Tcm-labelled red blood cells. The total radiation counts in a region of interest that includes either the right or the left lung increases during systole. On the average, the increase of the total pulmonary systolic radiation was found to be 62% of the systolic radiation decrease in the left ventricle region of interest. The discrepancy between the value of the systolic pulmonary blood volume increase and that of stroke volume is attributed to blood flow from the lungs into the left atrium during the cardiac systole period.

Adult↗
PubMed1991

Brain SPECT imaging in temporal lobe epilepsy.

Temporal lobe epilepsy is diagnosed by clinical symptoms and signs and by localization of an epileptogenic focus. A brain SPECT study of two patients with temporal lobe epilepsy, using 99mTc-HMPAO, was used to demonstrate a perfusion abnormality in the temporal lobe, while brain CT and MRI were non-contributory. The electroencephalogram, though abnormal, did not localize the diseased area. The potential role of the SPECT study in diagnosis and localization of temporal lobe epilepsy is discussed.

Adult↗
PubMed1983

The effects of intravenous norepinephrine on the local coupling between glucose utilization and blood flow in the rat brain.

Norepinephrine was infused intravenously in two groups of normal, awake rats. In one group local cerebral glucose utilization (LCGU) was measured by the deoxyglucose method (Sokoloff et al. 1977b); in the other group local cerebral blood flow (LCBF) was determined by the iodoantipyrine method (Sakurada et al. 1978). The experiments were performed during a stable state in which the heart rate was reduced between 36% (LCGU experiments) and 27% (LCBF experiments). Norepinephrine infusion reduced LCGU in all 39 structures measured between - 18 and - 37% from control values obtained in a group of normal non-infused rats. The decrease in LCGU was significant (P less than 0.05) in 38 of the 39 structures tested. LCBF was increased but not statistically significantly in most of the structures examined. When the LCGU values of the various structures during norepinephrine infusion were correlated with their corresponding LCBF values, a tight correlation (r = 0.94) was found indicating a close coupling between LCGU and LCBF during norepinephrine infusion. When compared to the relationship between LCGU and LCBF in a normal, non-infused control group, the slope of the regression line was increased significantly (P less than 0.01) by the norepinephrine infusion, indicating a resetting of the coupling mechanism. This means that, at a given metabolic rate, a higher blood flow is needed to perfuse a brain structure during norepinephrine infusion than during control conditions.

Animals↗
PubMed1983

Energy utilization and pyruvate as determinants of pyruvate dehydrogenase in norepinephrine-stimulated heart.

The quantitative effects of norepinephrine (NE) on the active form of the cardiac pyruvate dehydrogenase complex (PDCa) and the rate of oxidative decarboxylation of pyruvate (MVPyr) were compared with those of pyruvate (Pyr). Isolated working guinea pig hearts metabolized pyruvate alone or in combination with alternative energy-providing substrates (ketone bodies, octanoate, glucose). NE produced proportional increases in PDCa and myocardial oxygen uptake (MVO2). Total PDC activity (PDC1) remained constant. The PDCa/PDC1 ratios in NE depleted hearts (reserpine pretreatment) compared well with those in hearts containing endogenous NE, provided myocardial substrate supply and MVO2 were also comparable. No evidence was obtained indicating that NE or perfusate Ca2+ can dissociate PDCa or MVPyr from MVO2, even in presence of the alternative cosubstrates. In contrast, 0.2-10 mM Pyr produced stepwise but only submaximum increases in PDCa and MVPyr, with MVO2 remaining constant. Thus, at all Pyr concentrations tested, NE stimulations of myocaridal energy utilization and MVO2 were followed by further increases in PDCa and MVPyr. Evidently, pyruvate, and particularly cellular respiration are important determinants in the regulation of cardiac PDC, also during adrenergic stimulation of the heart.

Animals↗
PubMed1982

Adaptive changes of pyruvate oxidation in perfused heart during adrenergic stimulation.

Pyruvate oxidation was studied in isolated guinea pig hearts perfused under various conditions of work and stimulated by norepinephrine. Hearts metabolized pyruvate alone or in combination with 3-hydroxybutyrate or acetate as substrate. [1-14C]-pyruvate-dependent 14CO2 release into the venous effluent (MVpyr) was, like myocardial oxygen consumption (MVO2), directly related to aortic pressure or filling pressure. At high aortic pressures, ventricular pressure development and not work performance was the major determinant of MVO2 and thus MVpyr. With 1 mM pyruvate as sole substrate, 0.08 microM norepinephrine produced parallel changes in hemodynamic performance, MVO2. MVpyr, and pyruvate dehydrogenase complex (PDC) activity (active form). Similar and dose-dependent effects of norepinephrine were observed during infusion of 5 mM DL-3-hydroxybutyrate as cosubstrate. When 1 mM acetate was applied, MVpyr was also dependent on work performance and norepinephrine stimulation. However, in perfusions with 25 mM potassium chloride, norepinephrine did not enhance hemodynamic function or MVO2 and hence PDC activity and MVpyr. Thus regulation of the PDC in catecholamine-stimulated heart appears to be linked predominantly to myocardial energy demand even when alternative energy-providing substrates are utilized.

Animals↗
PubMed1980

Victimization and fear of crime in elderly public housing tenants.

Crime rate, personal victimization, and fear of crime were studied in relation to a variety of measures of well-being of 662 older people in 53 public housing sites. Findings indicated that fear of crime was central in determining psychological well-being; crime rate and victimization influenced well-being primarily if fear of crime intervened. On the other hand, these crime-related variables were minimally related to size of social space and activity outside the housing site. Age integration was strongly associated with fear of crime but did not increase with actual victimization except where age mixing was totally indiscriminate. Both cross-sectional and longitudinal data are analyzed in multiple-regression form and a path-analytic cross-sectional model is tested. It is concluded that planned housing serves a protective function for older tenants, and that older tenants are not necessarily made "prisoners in their homes" by either crime or fear of crime.

Aged↗
PubMed1980

Theophylline pharmacokinetics: variations between two similar study populations using oral oxtriphylline syrup.

The pharmacokinetics of two unmatched populations of asthmatic children, one from an asthmatic convalescent center in Denver and the other from an urban outpatient clinic, are compared after single and repeated dosing of a new asthma formulation, oxtriphylline syrup. Significant differences (p less than 0.05) in populations' theophylline total body clearance, apparent volume of distribution and absorption rates suggest future studies of multiple center design representing patterns of asthma more typical to the population at large would be more appropriate for selection of theophylline dosage guidelines.

Administration, Oral↗
PubMedDate not supplied

Protein/amino acid metabolism and nutrition in very low birth weight infants.

A large number of studies in recent years have described protein and nitrogen metabolism in the neonate. However, the majority of these data are difficult to interpret because of a number of confounding variables, particularly in very low birth weight (VLBW) infants. In contrast, application of state-of-the-art tracer isotopic and molecular biology methods in isolated cell system and whole animals has resulted in major advances in our understanding of the regulation of protein breakdown, synthesis, and protein accretion. The following workshop summary reviews the recent developments in basic physiology of protein metabolism in cellular and animal models in relation to human preterm infants, and identifies the important areas toward which future basic and clinical research should be directed to provide for optimal nitrogen accretion and growth of the VLBW infant.

Amino Acids↗