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Biomedical subjects

O Gonen

Publications and source records attributed to O Gonen.

30 records · Page 2Linked to original sources
PubMed1996

Simultaneous 3D NMR spectroscopy of fluorine and phosphorus in human liver during 5-fluorouracil chemotherapy.

Simultaneous multivoxel 31P and 19F 3D localized NMR spectroscopy is demonstrated on a phantom and in the liver of patients undergoing bolus-infusion 5-fluorouracil chemotherapy. The 19F and 31P spectra were localized with 8 x 8 x 8 3D chemical-shift imaging, with both nuclei sharing the same field of view and voxel size (27 and 64 ml in phantom and liver, respectively) using a 1.5-Tesla clinical imager with two RF channels and a dual-tuned surface coil. The repetition time (TR = 0.26 s) and Ernst nutation angles (theta E = 32 degrees for 19F, 28 degrees for 31P) were chosen to optimize the signal-to-noise ratio (SNR) per-unit time for the 0.5- to 2-s T1 range of the 19F and 31P metabolites of interest. The overall examination time, including tuning, imaging, shimming and dual-nuclear spectroscopy, was under 90 min. Simultaneous acquisition of 31P and 19F spectra will permit the study of the influence of hepatic and/or tumor metabolism on the uptake and catabolism of fluoropyrimidine drugs with no extra measurement time.

Adult↗
PubMed1995

Hybrid three dimensional (1D-Hadamard, 2D-chemical shift imaging) phosphorus localized spectroscopy of phantom and human brain.

A hybrid of two localized spectroscopy techniques, chemical shift imaging (CSI) and Hadamard spectroscopic imaging (HSI), is used to obtain an array of 16 x 16 x 4 (3 x 3 x 3 cm3 voxels) proton-decoupled phosphorus (31P) spectra of human brain. For equal spatial resolution, this organ's oblate shape requires fewer axial than coronal or sagittal slices. These different spatial requirements are well suited to 1D, 4th order, transverse HSI in the axial direction, combined with 2D 16 x 16 CSI in the other two orientations. The reduced localization matrix (16 x 16 x 4 over just the brain versus a cubic-16 x 16 x 16 matrix of equal resolution, over the entire head) may proportionally shorten data acquisition if the voxel size is not signal-to-noise limited. In addition, the use of Hadamard encoding can improve the intervoxel spectral isolation.

Aged↗
PubMed1995

The impact of different types of anesthesia on in vitro fertilization-embryo transfer treatment outcome.

OBJECTIVE: Our objective was to evaluate retrospectively the influence of different types of anesthesia on the outcome of ovum retrieval. METHODS: Sedation combined with local anesthesia was used on 120 occasions (Group I), epidural block in 139 ovum retrievals (Group II), and general anesthesia in 173 cycles (Group III). RESULTS: No differences were found in embryo yield or number or the quality of the embryo transferred. Of 99 pregnancies achieved, 66 live deliveries were recorded. Significantly lower clinical pregnancy rates were found in Group III (14.5%) compared with Group II (23.7%; P = 0.018) or Group I (25.8%; P = 0.0074). Highly significant differences were found in the delivery rates between Group III (8.7%), Group II (20.11%; P = 0.0017), and Group I (19.2%; P = 0.0043). CONCLUSION: The use of general anesthesia, especially nitrous oxide, for oocyte retrieval has an adverse effect on IVF outcome. This deleterious effect manifests itself only after embryo transfer and leads to lower pregnancy and delivery rates.

Adult↗
PubMed1994

Dual interleaved 1H and proton-decoupled-31P in vivo chemical shift imaging of human brain.

A technique is demonstrated to obtain interleaved proton (1H) and 1H-decoupled phosphorus (31P) spectra of human brain using 2D CSI. A modified commercial full-body imager and a dual-tuned birdcage head-coil were employed. Because proton relaxation times are shorter than those of phosphorus, TR(1H) can be chosen to be shorter than TR(31P), thus permitting a 1H acquisition to be inserted in each 31P cycle. The scheme results in significant time savings as both CSI data sets are obtained concurrently with patient loading, coil tuning, shimming, and imaging needed to be done only once.

Adult↗
PubMed1994

Simultaneous and interleaved multinuclear chemical-shift imaging, a method for concurrent, localized spectroscopy.

A method is proposed for carrying out chemical-shift imaging simultaneously on several nuclei (1H and 31P in this example), using a commercial clinical NMR imager fitted with a second RF channel and a dual-tuned birdcage coil to fit the human head. Nuclei of different gamma are examined at the same field of view by exciting each nucleus successively at times proportional to gamma during the same phase-encoding gradient waveform. Thus, each higher-gamma nucleus is exposed to a smaller area of the gradient. Additionally, since in vivo protons typically have a shorter T1 and roughly an order of magnitude higher sensitivity than phosphorus, it is possible to interleave 1H-only acquisitions between the simultaneous 1H, 31P observations while the lower-gamma nucleus relaxes. Consequently, additional information is obtained with either higher spatial resolution or greater sensitivity (more signal averaging) without lengthening the duration of the examination.

Computer Simulation↗
PubMed1994

Pregnancy-induced hypertension in rats with early adriamycin nephropathy.

In up to 60% of women with chronic renal disease an elevation of blood pressure is seen during pregnancy. The pathogenesis of this complication may be related to a diminished synthesis of vasodilatory substances by endothelial cells and to an increased sensitivity to vasopressor hormones such as angiotensin II. Previous experimental studies in rats with early chronic renal disease (adriamycin nephropathy, AN) have shown that this pregnancy-induced hypertension is associated with a lowered synthesis of glomerular PGE2. In the present study the vascular response to vasoactive substances was evaluated. In AN rats the sensitivity to an acute infusion of angiotensin II was augmented, whilst it was blunted in normal pregnant rats. Chronic treatment with the thromboxane-(Tx)-receptor antagonist, daltroban (60 mg/kg/day, p.o.) administered from mid-pregnancy induced a similar reduction in blood pressure in both AN virgin and pregnant rats. This suggests that adriamycin per se may induce vascular damage which may interfere with the normal vascular adaptation to pregnancy. Stimulation of NO synthesis with L-arginine decreased MAP values significantly in PAN rats but did not modify them during normal pregnancy. In additional experimental inhibition of the endothelial-derived relaxing factor (EDRF), nitric oxide (NO) synthesis with NAME from mid-pregnancy significantly increased SBP and MAP in normal rats. By contrast, in PAN rats chronic NAME treatment had no effect. In summary, the development of hypertension in pregnant rats with AN may be associated to endothelial cell dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMedDate not supplied

The prokinetic effect of domperidone in gallbladder--not upon dopaminergic receptors.

The mechanism of the contractile effect of domperidone on gallbladder smooth muscle has been investigated by using an in-vivo and an in-vitro model. In the in-vivo part of the study 14 healthy males were administered 20 mg domperidone or two placebo tablets orally and gallbladder emptying was measured by ultrasonography. The reduction in the gallbladder volume was significant compared to the placebo at 45 and 55 min. In the in-vitro part of the study, the gallbladder strips isolated from guinea pigs were field stimulated and 10(-6)-10(-4) M concentrations of dopamine were administered before electrical field stimulation (EFS) was repeated. Dopamine exerted no significant effect upon the contractions obtained by EFS. The effect of dopamine and domperidone under basal conditions were also explored. Under basal conditions, dopamine neither contracted nor relaxed the gallbladder muscle between 10(-6) and 10(-4) M concentrations when added directly to the organ bath. Besides, a significant contraction was observed with 10(-4) M concentration of domperidone whereas 10(-7), 10(-6) and 10(-5) M concentrations exerted no effect. This effect of domperidone was thought to be nonspecific but inhibited by 10(-6) M atropine, 10(-5) M pirenzepine and abolished by 10(-6) M tetrodotoxin. In summary, domperidone produces a modest contraction in human gallbladder. This effect does not seem to occur upon dopaminergic receptors in guinea pig models.

Adult↗
PubMedDate not supplied

Effect of smoking on concentration, motility and zona-free hamster test on human sperm.

The effect of smoking on sperm concentration, motility, and zona-free hamster egg sperm penetration assay (SPA) was evaluated in 293 smokers of more than 10 cigarettes/day and 382 nonsmokers. Prerequisites for inclusion in the study were sperm concentration of greater than 10 x 10(6)/ml, sperm motility of greater than 30%, and normal morphology of greater than 60%. Although a lower sperm concentration was found in smokers, no significant difference was observed in sperm motility and SPA.

Adult↗
PubMedDate not supplied

Whole-brain N-acetylaspartate spectroscopy and diffusion tensor imaging in patients with newly diagnosed gliomas: a preliminary study.

BACKGROUND AND PURPOSE: Glial cancer cells can be found well beyond the MR imaging T2 signal-intensity hyperintensity. To quantify the extent of the diffuse microstructural tissue damage possibly due to the presence of these satellite tumor cells, we investigated the relationships between global metabolic and microstructural abnormalities in the normal-appearing brain regions of patients with newly diagnosed glioma. MATERIAL AND METHODS: Ten patients (6 men, 4 women) with radiologically suspected untreated supratentorial glial tumors and 9 healthy controls (5 men, 4 women) were studied with T1- and T2-weighted MR imaging, diffusion-weighted echo-planar MR imaging, and whole-brain N-acetylaspartate (WBNAA) proton MR spectroscopy. The relationship between the WBNAA concentration, the mean diffusivity (MD), and fractional anisotropy (FA) values in a large contralateral normal-appearing white matter (NAWM) brain region was investigated with the Spearman rank correlation test. RESULTS: WBNAA values were significantly lower (P < .001) in patients (9.7 +/- 1.7 mmol/L) than controls (13.1 +/- 1.1 mmol/L). MD values were higher (P = .0001) in patients (0.95 +/- 0.07 mm(2)s(-1)) than in controls (0.61 +/- 0.04 mm(2)s(-1)). FA values did not differ between patients (0.42 +/- 0.08) and controls (0.43 +/- 0.041). A strong inverse correlation between WBNAA and MD (r = -0.88, P = .0008) was found in the patients but not in controls (r = 0.012, P = .975). CONCLUSION: The correlation between the WBNAA and MD in the contralateral NAWM suggests that the microstructural damage possibly related to the presence of infiltrative tumor cells contributes to WBNAA decline in these patients.

Adult↗