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Biomedical subjects

A Frenkel

Publications and source records attributed to A Frenkel.

At least 19 recordsLinked to original sources
PubMed1992

Marginal leakage of class II glass ionomer-composite resin restorations: an in vitro study.

This in vitro study assessed the sealing properties of two metal-reinforced glass ionomer cements, used as "extended bases" in glass ionomer-composite resin restorations. Two class II cavities were prepared in the proximal surfaces of 30 molars. The gingival margin of one was prepared in enamel and the other in cementum/dentin. Fifteen teeth (30 cavities) were restored with Ketac Silver material used as an extended base (group A). In the remaining 15 teeth (30 cavities), the extended base was in Miracle Mix material (group B). All occlusal surfaces were restored with Estilux Posterior Material. The restored teeth were thermocycled, immersed in fuchsin, washed in water, embedded, sectioned, and examined under a dissecting microscope. All restorations with margins in cementum/dentin of group A (Ketac Silver) leaked. No microleakage occurred in 12 of the 30 restorations with margins in cementum/dentin of group B (Miracle Mix). In addition, severe microleakage was present in 24 teeth of group A, as opposed to three in group B. It was concluded that the sealing properties of Miracle Mix material are superior to those of Ketac Silver material, in vitro.

Cermet Cements↗
PubMed1992

Local and systemic effects of radiation on bone metabolism measured by quantitative SPECT.

Quantitative bone scintigraphy (QBS), which measures 99mTc-MDP uptake expressed as percent of injected dose per cc, indicates bone metabolism. It is measured in the bones of patients before and after radiation treatment and then compared to normal controls. QBS was performed in a group of 22 normal individuals and was measured twice, 2-10 mo (mean 4.9) apart. There was no significant difference between the two measurements. QBS was performed also in 28 patients before, immediately after and at certain time intervals after radiation therapy for cancer. Both the irradiated and the nonirradiated bones showed significant decreases in bone metabolism at 2-18 mo (mean 8.8) after irradiation. In addition, increases and decreases of 99mTc-MDP uptake were similar in the irradiated and in the nonirradiated bones, and there were significant correlations of the QBS values in the different bones of each individual patient. The etiology of the changes in bone metabolism in the nonirradiated bones is not yet fully understood, but it appears to be the result of a systemic effect of radiation.

Bone and Bones↗
PubMed1992

Radionuclide assessment of penile corporal venous leak using technetium-99m-labeled red blood cells.

In an attempt to evaluate penile corporal venous outflow, a method that utilizes intracorporal injection of Tc-RBC was developed and used in 20 patients with erectile dysfunction. Seven patients showed venous leak and 13 had normal venous outflow. Technetium-labeled RBC corporal clearance in the flaccid state and after intracorporal injection of papaverine (30 mg) and regitine (1 mg) were assessed in sequence by two separate injections of 18.5 MBq of Tc-RBC each. The time for 50% corporal clearance (T50%) was determined from the time activity curves obtained in flaccid state and after intracorporal injection of the vasoactive agent. There were no statistically significant differences in T50% measured in the flaccid state between normal venous outflow (202 +/- 139 sec) and venous leak (92 +/- 35 sec, p = 0.1). However, after intracorporal injection of papaverine and regitine a significant increase in the T50% was noted in normal venous outflow (2892 +/- 1899 sec) as compared to venous leak (213 +/- 123 sec, p less than 0.001). The results suggest that measurement of corporal clearance of Tc-RBC after intracorporal injection of papaverine may be a useful method in detecting venous leak, and could be used as a screening test in patients with erectile dysfunction.

Adult↗
PubMed1991

In vivo measurements of the fraction of dose of bleomycin labeled with cobalt 57 delivered to human tumors.

Concentrations of bleomycin labeled with cobalt 57 (Co-bleo) over time were measured in vivo in 17 patients with 32 sites of lymphoma and 18 patients with lung tumors after administration of the same dose of bleomycin. There were marked variations in individual tumor drug concentrations even among tumors with the same histologic type, indicating that the tumor concentration of this drug in individuals cannot be predicted from the administered dose. Also, tumor concentration could not be predicted from the area under the concentration over time curve (AUC) of Co-bleo in the blood; there was no correlation (r = 0.53) between the AUC and the concentration in the tumor at any point in time between 30 minutes and 8 hours after injection. There was no significant difference in the percent of the injected dose per milliliter (%ID/ml) which was delivered to the tumor when low and high amounts of bleomycin were administered to the same patient. Also, a good correlation (r = 0.88) between the %ID/ml over time was found when injection of low and high doses of bleomycin were compared. The results indicate that using quantitative single photon emission computed tomography (SPECT) and a labeled tracer dose it is possible to predict what fraction of the dose of a chemotherapeutic drug will concentrate in an individual patient's tumor in vivo. They also show that, for bleomycin, escalation of dose will result in a proportional increase of tumor concentration. This increase depends on individual properties of tumors which can be measured quantitatively in vivo by SPECT and are expressed as percent of %ID/ml of tumor tissue.

Adolescent↗
PubMed1991

Effect of extracorporeal piezoelectric lithotripsy shock waves on renal function measured by Tc-99m-DMSA using SPECT.

Extracorporeal shock-wave lithotripsy has altered the therapeutic approach to urinary stone disease. Recently, a method was developed in which shock-wave generation is obtained piezoelectrically. To evaluate the effect of extracorporeal piezoelectric lithotripsy (EPL) on renal function, 20 patients were studied prior to and after EPL of renal calculi. Renal cortical function was evaluated by using a previously described and validated quantitative single photon emission computerized tomography (SPECT) method to measure individual absolute uptake of technetium-99m dimercaptosuccinic acid (Tc-99m-DMSA). Twenty kidneys were treated, and the 19 contralateral kidneys were without stone disease (1 patient had a single kidney). The absolute kidney uptake of Tc-DMSA in the normal kidneys was 21.4% +/- 6.2% before and 22.2% +/- 6.4% after EPL. For the treated kidneys the absolute update was 16.8% +/- 5.3% and 16.8% +/- 4.7% before and after, respectively. There was no statistical significant difference between pre- and post-treatment values. The absolute kidney uptake was significantly lower (p less than 0.01) in the treated than in the normal kidneys. This study indicates that the EPL procedure did not cause any damage to cortical function detectable by the DMSA uptake.

Adult↗
PubMed1991

Radionuclide assessment of bladder-emptying function in normal male population and in patients before and after prostatectomy.

Radionuclide assessment of the bladder-emptying function was evaluated in 82 normal individuals and in 16 patients before and after prostatectomy. The parameters evaluated were: average flow rate (AFR), peak flow rate (PFR), corrected peak flow rate (CPFR = PFR/[bladder volume] 0.5), ejection fraction (EF) of the bladder, and post-voiding residual urine (RU) volume. A good interobserver reproducibility was found in 19 measurements. Urinary flow rates, EF, and RU showed a highly significant statistical difference between normal individuals and patients before surgery: AFR, 9.2 +/- 5.1 vs. 2.9 +/- 1.5 mL/sec; PFR, 19.5 +/- 9.2 vs 7.4 +/- 3.2 mL/sec; CPFR, 1.17 +/- 0.34 vs 0.54 +/- 0.22; EF, 95.6 +/- 4.6 vs 68.2 +/- 23.2 percent; and RU, 11.8 +/- 15.8 vs 93.4 +/- 115 mL; respectively. After prostatectomy the urinary flow rates showed a highly significant improvement and did not differ from the normal individuals: AFR, 7.9 +/- 2.7 mL/sec; PFR, 19.0 +/- 6.4 mL/sec; and CPFR, 1.32 +/- 0.57. The EF after surgery (91.7 +/- 10.9%) was lower than in normal individuals, but showed a significant improvement compared with EF before surgery. The RU after surgery (27.4 +/- 48.0 mL) although lower than before surgery did not differ significantly and was greater than in the normal individuals. No relationship between age and flow was found in this study. Both average and peak flow rates were related to the bladder volume. This method involves a single, noninvasive procedure which enables determination of bladder-emptying function.

Adult↗
PubMed1991

Marginal leakage around V-shaped cavities restored with glass-ionomer cements: an in vitro study.

The object of this investigation was to assess the degree of marginal leakage around V-shaped cervical glass-ionomer cement restorations and compare it to that around composite resin restorations. Three different glass-ionomer cements and one composite resin control were assessed by means of dye penetration. Severe microleakage at the occlusal margins was found in 70% of the glass-ionomer cement restorations, but in only 10% of the composite resin restorations. A considerable amount of dye penetration was observed at the cervical margins of all restorations, including the controls. None of the glass-ionomer cements tested showed superiority in preventing marginal leakage occlusally or gingivally.

Bicuspid↗
PubMed1991

Renal function and technetium-99m-dimercaptosuccinic acid uptake in single kidneys: the value of in vivo SPECT quantitation.

The ability to evaluate kidney function in each kidney separately by quantitative SPECT was tested in 20 patients with a single kidney and varying degrees of renal disease. Technetium-99m-dimercaptosuccinic acid (99mTc-DMSA) uptake was compared with renal function measured by creatinine clearance and serum creatinine. There was a good correlation for both serum creatinine (r = 0.89, y = 24.6 *X -1.15, error = 5.6, p less than 0.001) and creatinine clearance (r = 0.76, y = 0.6 *X 0.84, error = 8.0, p less than 0.001). The results indicate that SPECT quantitation of 99mTc-DMSA uptake can be used as an indicator of the function of each kidney individually.

Adult↗
PubMed1990

Normal and abnormal Ga-67 SPECT anatomy in patients with lymphoma.

The appearance of normal Ga-67 SPECT images in the coronal, sagittal and transaxial planes is described. The normal tomographic appearance of bone, liver, spleen, and gut is shown and compared with disease involvement above and below the diaphragm.

Gallium Radioisotopes↗
PubMed1990

Functional changes in the brainstem auditory pathways following open-heart surgery.

Measurements of the auditory brainstem responses (ABR) were used to assess the functional integrity of the brainstem auditory pathways following open-heart surgery. Recording of ABR was performed in 31 patients before and after open-heart surgery. The values of ABR measurements were compared to those of a control group of normal-hearing subjects. Postoperative aberrations in ABR were observed in 12 patients. Brainstem transmission time measured as wave I to wave V interpeak latency (I-V IPL) was prolonged in 6 patients and shortened in 8 patients. Concomitant impairment in hearing function was not present, and therefore, these changes most probably reflected a functional alteration in the neurological status of the brainstem. Possible explanations of the postoperative changes in I-V IPL are discussed, however, further studies are needed to clarify the pathogenesis of these changes. Measurement of ABR may prove to be an important adjunct in the overall assessment of the neurological status following open-heart surgery.

Adult↗
PubMed1990

Administered dose and tumor dose of bleomycin labeled with cobalt-57 in mice and men.

Tumor concentrations of the chemotherapeutic drug, bleomycin, labeled with cobalt-57 (Co-bleo) were compared in mouse tumor models and in human lung tumors using quantitative single-photon emission computed tomography. Drug concentrations in histologically similar human tumors showed marked variability for the same injected dose (ID). Small cell carcinomas showed concentrations between 1.09 and 8.85 %ID/cc x 10(-3) while non-small cell lung tumors showed a concentration variation between 0.36 and 6.75 %ID/cc x 10(-3). In contrast to the situation in human tumors, uptake in mouse tumors showed only slight variability in animals with the same tumor model. EMT-6 tumors in mice showed at 6 hr significantly higher uptake of Co-bleo (p less than 0.001) and significantly higher tumor-to-lung ratio (p less than 0.001) when compared to murine fibrosarcomas. The EMT-6 tumors in contrast to the fibrosarcomas responded to bleomycin treatment in a dose dependent manner. The results indicate that while in mice the tumor dose closely follows the administered dose, in humans, the tumor dose and the tumor-to-lung ratio in the individual patient cannot be predicted from the administered dose.

Aged↗
PubMed1990

Efficacy of long-term fluoxetine treatment of obsessive-compulsive disorder.

Ten outpatients meeting DSM-III-R criteria for obsessive-compulsive disorder completed a 32-week, open-label study with fluoxetine, a selective serotonin reuptake blocker. The patients were evaluated every four weeks for obsessive-compulsive symptomatology, anxiety, and depression. Significant improvement of obsessive-compulsive and anxiety measures were observed after four weeks, with maximal improvement at eight weeks. Depressed and nondepressed patients showed similar rates of improvement in obsessive-compulsive symptomatology. Overall, fluoxetine was tolerated well by all patients, and no serious side effects were observed. This study suggests that fluoxetine is an effective and safe treatment for obsessive-compulsive disorder, both for short-term alleviation and for long-term maintenance.

Body Weight↗
PubMed1990

SPECT quantitation of iodine-131 concentration in phantoms and human tumors.

The validity of SPECT measurement of iodine-131 (131I) concentration was tested in vitro in phantoms and in vivo by measuring bladder urine concentrations. Phantom studies comparing known and SPECT measured concentrations showed a good correlation for 131I (r = 0.98, s.e.e. = 20.94 counts/voxel) for phantoms of 25 to 127 cc and concentrations of 0.13 to 9.5 microCi/cc. The in vivo, in vitro correlation of 131I concentrations in the urine was also good (r = 0.98, s.e.e. = 0.677 microCi/cc). Quantitative SPECT was used to calculate the effective half-life and dosimetry of radioiodine in 12 sites of thyroid carcinoma in seven patients. SPECT was also used to determine the dosimetry of [131I]MIBG (metaiodobenzylguanidine) in two patients with carcinoid, two with neuroblastoma, and one with pheochromocytoma. The radiation dose for thyroid carcinoma metastases varied between 6.3 and 276.9 rad/mCi. The dose from MIBG varied between 13.4 and 57.8 rad/mCi. These results indicate the validity of quantitative SPECT for in vivo measurement of 131I and the need to measure the concentration of 131I in individual human tumor sites.

3-Iodobenzylguanidine↗
PubMed1989

The concentration of bleomycin labeled with Co-57 in primary and metastatic tumors.

The concentration over time of bleomycin labeled with Co-57 was measured in 39 primary and metastatic tumor sites in 16 patients using a newly developed and validated single photon emission computed tomography (SPECT) method. There were nine primary tumors, 15 metastatic tumors, and five multifocal lymphomas. Co-bleomycin concentrations also were measured in primary and metastatic B-16 melanoma tumors in mice. In humans, metastases to lymph nodes (1.58 +/- 0.51 %ID/ml X minutes) showed significantly higher (P less than 0.01) tumor cumulative concentrations of Co-bleomycin than metastases to liver, bone, lung, and brain (0.76 +/- 0.20 %ID/ml X minutes). The cumulative concentrations of Co-bleomycin in human lymphomas (1.1 +/- 0.25 %ID/ml X minutes) also were significantly higher (P less than 0.01) than the concentrations in human metastases other than lymph nodes. The cumulative concentration in cerebral metastases (0.65 +/- 0.18 %ID/ml X minutes) was significantly lower (P less than 0.05) than in noncerebral metastases (1.22 +/- 0.53 %ID/ml X minutes). Primary tumors in humans showed higher concentrations of Co-bleomycin than metastases, except for lymph nodes. In contrast with humans, murine metastases showed higher concentrations of Co-bleomycin (6.20 +/- 2.65 %ID/g) than primary tumors (2.94 +/- 0.90 %ID/g) (P less than 0.001). The concentrations of Co-bleomycin in murine tumors that were affected by bleomycin were about three orders of magnitude higher than in human tumors. The results of this in vivo study document the differences in drug delivery of Co-57-labeled bleomycin to human primary and metastatic tumors and show differences in drug delivery between human and murine tumors.

Adolescent↗
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↗
PubMed1989

Quantitative bone scintigraphy using SPECT.

A quantitative single photon emission computed tomography (SPECT) technique for measuring radiopharmaceutical uptake in humans has been applied to bone scintigraphy. The method was validated by comparing SPECT measured percent of injected [99mTc]MDP in 16 normal skulls with well counter measurements of samples of the same bones obtained at surgery. A very good correlation (r = 0.96) was found. A very good interobserver correlation (r = 0.99) and agreement were also obtained when using quantitative bone scintigraphy (QBS). Control SPECT studies of uptake in the right and left iliac bones and the right and left sacroiliac regions in each patient showed no significant differences between the contralateral sides. Studies done in seven subjects at 2 and 4 hr after the same injection and in nine subjects 4 to 8 mo later in the same subjects showed a very good agreement and no significant differences between the two measurements were found. QBS is suggested as an accurate and reproducible index for assessment of the mass of remodeling bone. Preliminary results showed differences in QBS of normal subjects at different ages. A group of 68 young patients aged 18-26 yr showed a significant higher QBS (p less than 0.001) when compared to an older group of 62 patients aged 50-85 yr. There was, however, a wide range of uptake values for the same bone in the same group, suggesting that the method should best be used for following individual patients over time.

Adult↗