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Biomedical subjects

S Zakko

Publications and source records attributed to S Zakko.

13 recordsLinked to original sources
PubMed1995

A method to quantitatively compare in vivo the effects of gallstone solvents on intestinal mucosal function: a controlled study comparing mono-octanoin with methyl tert-butyl ether in the rat.

During contact dissolution of gallstones, solvents may escape from the gallbladder and damage the intestinal mucosa. In order to compare the extent of this potential injury, we developed a method to objectively quantify the effects of two commonly used cholesterol solvents, methyl tert-butyl ether and mono-octanoin, on mucosal transport function in the rat intestine. Two intestinal segments in each of 184 anesthetized rats were cannulated. Three milliliters of either solvent were instilled in one segment and left for varying periods of time, while saline was instilled in the other as control. The segments were then washed and perfused for 45 min with an isotonic solution containing [3H]polyethylene glycol 4000 (a nonabsorbable reference marker) and either [14C]alpha-aminoisobutyric acid (a marker for active absorption) or [14C]mannitol (a marker for passive permeability). Methyl tert-butyl ether caused more inhibition of alpha-aminoisobutyric acid absorption (64%) than mono-octanoin (48%) and a greater reduction of dry weight per centimeter of the perfused segment (22%) compared with mono-octanoin (10%). Such effects appeared after only 1 min of solvent exposure and did not appreciably increase with longer exposures. Permeation of mannitol increased by 26% after 1 min of exposure to mono-octanoin and by 54% after a similar period of exposure to methyl tert-butyl ether. Longer exposures to both solvents did not seem to cause progressive increases in mannitol permeation. The results indicate that brief exposure of the rat jejunum to either of the two solvents causes a reduction in active transport ([14C]alpha-aminoisobutyric acid absorption), an increase in passive permeability (mannitol permeation), and a loss of mucosal constituents. We conclude that the intestinal mucosa is susceptible to solvent damage and may be used as a selectively sensitive model that can characterize the biological injury of gallstone solvents. The study also suggests that escape of the currently available solvents into the small intestine in patients undergoing contact dissolution of gallbladder stones may cause injury to the small intestine.

Animals↗
PubMed1995

Brain death: the evaluation of semi-quantitative parameters and other signs in HMPAO scintigraphy.

The aim of this study was to facilitate the diagnosis of brain death based on semi-quantitative parameters as well as the other scintigraphic signs and symptoms of brain death. Altogether, 72 studies were performed in 54 patients (35 males, 19 females) to evaluate the diagnoses of brain death which were confirmed in 49 cases. Perfusion dynamic acquisition and static imaging were performed after the intravenous injection of 700-900 MBq 99Tcm-hexamethylpropyleneamine oxime (HMPAO). We reviewed the following parameters retrospectively: (1) qualitative visual assessment of the presence or absence of delayed HMPAO deposition in the brain area; (2) qualitative visual assessment of a 'three-pronged fork' of the cerebral arteries during the first-pass study; (3) any evidence of 'hollow skull' during the first-pass study; (4) any evidence of 'hot nose'; (5) blood flow index (i.e. the ratio of the area under the brain time-activity curve vs that under the curve for the carotid arteries); and (6) delayed uptake index (i.e. the ratio of HMPAO deposition in the brain vs that in the facial regions of interest). We were able to demonstrate the validity of individual signs and symptoms and to confirm the highly reliable nature of semi-quantitative scintigraphic parameters.

Adolescent↗
PubMed1994

Kidney volume estimation using 99Tcm-DMSA RSPECT: evaluation by phantom study.

Renal parenchymal volume is important for clinical interpretation. The phantom study was carried out to validate the volume calculation. The volume of kidney phantom was determined using reoriented single photon emission computed tomography (RSPECT). The phantom volume range was 20-300 ml. There are two major factors in the determination of volume which are radioactivity concentration and organ/background ratio. Our results showed that the effect of radioactivity concentration on the volume in the kidney phantom is -3.3 to 7.5% whereas the effect of organ/background ration was only 2.2%. Our relative volume deviation, therefore, from the real volume was 1.43%. We concluded that it is feasible to use kidney volume in clinical work.

Evaluation Studies as Topic↗
PubMed1994

Comparison of planar and SPECT 99Tcm-dimercaptosuccinic acid scintigraphy in calculating differential kidney function.

An extensive study to compare planar and single photon emission computed tomographic (SPECT) 99Tcm-dimercaptosuccinic acid (DMSA) determination of differential kidney function (DKF) has been carried out. The study has demonstrated that it is possible to use SPECT differential kidney function in place of that obtained using planar scintigraphy. The SPECT DKF value correlated with the planar DKF value. Gradient shaded three-dimensional surface images, reoriented transaxial, sagittal and coronal slices were produced during the same processing method.

Adolescent↗
PubMed1991

Human gallbladder morphology after gallstone dissolution with methyl tert-butyl ether.

The effects of methyl tert-butyl ether exposure on the human gallbladder in five patients who were treated for gallstones by contact dissolution is described. Two patients underwent cholecystectomy within 1 week of methyl tert-butyl ether treatment, one patient 2 weeks after, another 10 weeks after, and one 12 weeks after. Indications for cholecystectomy were bilirubinate stones (resistant to methyl tert-butyl ether), catheter dislodgement, bile leakage, and gallstone recurrence (2 patients). Gallstones were dissolved completely in three patients, there was approximately 50% stone reduction in one patient, and no dissolution occurred in the fifth patient. Each gallbladder was examined grossly and histologically. Electron microscopic evaluation was performed in one cases. Typical inflammatory findings of chronic cholecystitis were observed in each gallbladder and were most conspicuous in the submucosa; the mucosal and serosal surfaces were intact. Mild acute inflammatory changes were noted in the submucosa in the two patients with the shortest interval between methyl tert-butyl ether administration and cholecystectomy. There were no ulcerations in the mucosa and no unusual wall thickening or fibrosis in any patient. These observations support the safety of methyl tert-butyl ether perfusion in the human gallbladder; the mild acute changes may be a transient and reversible phenomenon.

Cholecystectomy↗
PubMed1989

Interventional radiology in the gallbladder.

This article is a pictorial review of the current status of interventional radiology of the gallbladder. The indications and technical aspects of various procedures are presented. Specifically discussed are: (1) needle puncture for percutaneous biopsy, withdrawal of bile for culture, or imaging of the biliary tract; (2) catheter insertion for decompression or abscess drainage; and (3) gallstone management via contact dissolution, fragmentation and basketing, or contact lithotripsy. The management of vagal hypotension and bile leak, the major complication of these procedures is also discussed.

Catheterization↗
PubMed1986

Effects of vanadate on water and electrolyte transport in rat jejunum.

The effect of vanadate (orthovanadate, VO4-) on water and ion transport was studied in rat jejunum. Water transport was tested by single-pass perfusion in vivo and ion fluxes by the Ussing-chamber technique in vitro. The results suggest that vanadate has two actions on ion and water transport: At low concentrations (10(-4) M) it causes Cl-, Na+ and water secretion by stimulation of adenylate cyclase; At higher concentrations (10(-3) and 10(-2) M) it decreases net absorption of Na+ and Cl- by inhibition of (Na+ + K+)-ATPase.

Adenylyl Cyclases↗
PubMedDate not supplied

Diagnostic imaging before and after dissolution of gallbladder stones.

Ultrasonography is currently the most sensitive non-invasive imaging modality for the diagnosis of gallbladder stones. It has low sensitivity, however, for the detection of fine residue, stone debris, or mucosal ulcers after percutaneous chemical contact dissolution of gallstones. Percutaneous endoscopy is much more sensitive and specific for this purpose. Computed tomography of the gallbladder and gallstones, when properly used, can help in identifying patients suitable for percutaneous contact dissolution of gallstones using cholesterol solvent such as methyl tert-butyl ether. Attention to details and appropriate analysis of the data obtained will overcome many of the shortcomings in the majority of studies that failed to appropriately correlate CT findings with gallstone dissolvability.

Cholelithiasis↗
PubMedDate not supplied

Chemical contact dissolution of cholesterol gallbladder stones. One hundred years later.

The demonstration that methyl tert-butyl ether is a safe and effective gallstone solvent and the development of the microprocessor-assisted solvent transfer system have revived the procedure of chemical contact dissolution of gallbladder stones, which was first described 100 years ago. This procedure of automatic computerized solvent litholysis is further enhanced by the development of a CT-index for the selection of patients with amenable stones and percutaneous gallbladder endoscopy for evaluation after dissolution. Preliminary studies have shown that ACSL with MTBE is safe and highly effective for gallbladder stone dissolution, making this technique a viable non-surgical alternative for the treatment of gallbladder stones. The emergence of new safer and more effective solvent such as ethyl propionate along with the procedure of percutaneous gallbladder ablation for the definitive prevention of gallstone recurrence promise to render ACSL highly competitive even with laparoscopic cholecystectomy.

Catheterization↗