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S Ben-Haim

Publications and source records attributed to S Ben-Haim.

42 records · Page 3Linked to original sources
PubMed1989

A practical SPECT technique for quantitation of drug delivery to human tumors and organ absorbed radiation dose.

A practical quantitative single photon emission computed tomographic (SPECT) technique based on an empirical threshold analysis permits accurate measurements in humans of drug delivery and absorbed radiation dose. The limits of the method have been explored using a wide range of phantom volumes, concentrations, and target-to-nontarget ratios. A threshold of 43% was found to give the best results using volumes of 30 to 3,800 cc. An excellent correlation (r = .99 with a standard error of estimate [SEE] of 41 cc) was found between SPECT measured volumes and actual phantom volumes. A similarly high correlation (r = .98, SEE = 260 counts/voxel) was found in 77 measurements of concentrations between 0.01 and 3.6 microCi/cc. There was a direct relationship between the target-to-nontarget ratio of phantoms and the accuracy of volume measurements. The technique has been validated by an excellent in vivo/in vitro correlation of uptake in human tumors. The tumor cumulative concentration and tumor-to-blood ratio were used for assessment of drug delivery. In vivo quantitative measurements of the pharmacokinetics of technetium-99m (99mTc) glucoheptonate, cobalt-57 (57Co) bleomycin and platinum-195m (195mPt) cisplatin in human tumors in vivo indicates that, in contrast with tumor models in animals, there is a marked variability in drug delivery even in tumors with the same histology. Future development of labeled drugs should make it possible to use quantitative SPECT for predicting tumor response to therapy and for tailoring chemotherapy for the individual patient under treatment. SPECT quantitation of organ concentration was used for Medical Internal Radiation Dose committee (MIRD) calculations of organ absorbed radiation dose from 99mTc-labeled RBCs. Excellent in vivo/in vitro correlations were obtained between SPECT measured concentrations of blood radioactivity in the heart and in vitro measurements of blood samples. The possibilities and limitations of this technique are discussed and its use for in vivo measurement in humans of absorbed radiation dose from radiopharmaceuticals is suggested.

Contrast Media↗
PubMed1988

Gallium 67 imaging in monitoring lymphoma response to treatment.

The value of gallium 67 (Ga) imaging in monitoring lymphoma response to treatment was assessed in 25 patients with Ga-avid tumors and compared to body computed tomography (CT), chest radiographs, and palpation of tumor infiltrated peripheral lymph nodes. Ga imaging was negative in 95% (20/21) of the patients who were clinically considered to be in remission and in whom treatment was stopped. The disease did not recur during a follow-up of 12 to 26 months in 15 patients. Six patients developed recurrence of the disease 3 to 12 months after treatment was stopped. In all six patients Ga imaging became positive again at the time of the appearance of active disease. In the group of patients in remission, CT was negative in 57% (11/19), chest x-rays in 55% (6/11) and peripheral lymph nodes were palpated in none of the patients (13/13). In four patients that did not achieve remission after treatment, Ga scans were positive. Ga imaging appears useful in monitoring lymphoma response to treatment. This is probably because Ga imaging monitors tumor cell viability, whereas body CT and chest radiographs show the tumor mass, which may consist of fibrotic or necrotic tissue.

Adolescent↗
PubMed1986

Low-set osmotic threshold for vasopressin release in a patient with prolactinoma.

This report describes a 38-year-old patient with prolactinoma, without adrenal or thyroid insufficiency, with syndrome of inappropriate secretion of vasopressin due to downward resetting of the hypothalamic osmoreceptors. Random measurements of plasma and urine osmolality revealed an inappropriately high urine osmolality for a given plasma osmolality. Simultaneous plasma vasopressin levels were within normal limits. Urine dilution after water load was normal. During infusion of hypertonic saline, the osmotic threshold was demonstrated at plasma osmolality of 267 mosmol/kg, which is markedly lower than the normal 287.3 +/- 3.3 mosmol/kg. Thirst sensation seemed to be intact. The defect in the osmoreceptor function might have been induced by the tumor mass or by chronic hyperprolactinemia.

Adrenocorticotropic Hormone↗
PubMed1986

Osmotic threshold for vasopressin release in hyperprolactinemic patients.

Eleven patients with chronic hyperprolactinemia were tested to determine their osmotic threshold by isovolemic infusion of 5% NaCl. The results obtained demonstrate no statistical difference from known values in healthy volunteers. No linear correlation was found between levels of blood prolactin and the osmotic threshold, except for 1 patient who represents downward resetting of the hypothalamic osmoreceptors. The average time elapsed from the maximal dilution point to the osmotic threshold in hyperprolactinemia was found to be significantly shorter than in the normal population. We conclude that prolactin does not appear to participate in the osmotic regulation in man.

Adolescent↗
PubMed1983

Post-cough heart rate response: influence of age, sex, and basal blood pressure.

Although the chronotropic response to cough may provide an index of the capacity for cardioacceleration, how the heart rate change may be influenced by age is not established. In 213 healthy men and women aged 20-90 yr we measured the heart rate response following three forceful coughs performed over a 3-s period. Resting heart rate was not age related. Increasing age was associated with a linear reduction in cough-induced maximum rise in heart rate (r = -0.58, P less than 0.0001) and a prolongation of the time to peak heart rate (P less than 0.001). The responses were not different between women and men. Multiple regression analysis performed on age and systolic, diastolic, and mean basal arterial pressure measurements revealed that age was the sole variable that correlated significantly with peak heart rate response. Thus advancing age is associated with a decline in the amplitude and rapidity of the chronotropic response to cough. These age-related changes are independent of the basal arterial pressure and may contribute to the decreased cardiovascular homeostatic response to stress, such as upright posture or volume depletion, which is commonly observed in the elderly.

Adult↗