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Biomedical subjects

R Chisin

Publications and source records attributed to R Chisin.

At least 73 records · Page 4Linked to original sources
PubMed1992

Splenic infarction: a complication of cardiac catheterization.

Patients with extensive atherosclerosis are at increased risk of developing embolic complications during cardiac catheterization. We describe a 51-year-old man with unstable angina and bilateral leg claudication who developed fever and right upper abdominal pain shortly after cardiac catheterization. Liver-spleen scintigraphy demonstrated a wedge-shaped filling defect compatible with splenic infarction, and serial scans performed over a period of five months showed resolution of this finding. Splenic infarction tends to be under-diagnosed, and physicians should be aware of this potentially serious complication of cardiac catheterization.

Cardiac Catheterization↗
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

Pharmacokinetic and imaging studies in patients receiving a formulation of liposome-associated adriamycin.

Pharmacokinetic and imaging studies in 19 patients receiving liposome-entrapped adriamycin (L-ADM) were carried out within the framework of a Phase I clinical trial (Gabizon et al., 1989a). The formulation of L-ADM tested consisted of 0.2 microM-extruded multilamellar vesicles composed of egg phosphatidylcholine, egg-derived phosphatidyl-glycerol (PG), cholesterol, and ADM intercalated in the fluid lipid bilayer. Plasma clearance of total drug extracted from the plasma after L-ADM infusion followed a biexponential curve with a pattern similar to that reported for free ADM. The plasma concentration of drug circulating in liposome-associated from was also measured in a subgroup of seven patients. Liposome-associated drug was found to be rapidly cleared from plasma. Its ratio to non-liposome-associated drug appeared to correlate with liver reserve, with highest ratios in patients with normal liver function. Liposome clearance, as measured by the plasma concentration of PG in three patients was slower than the clearance of liposome-associated ADM, suggesting that liposomes lose part of their drug payload during circulation. To learn about the liposome organ distribution, imaging studies were carried out with 111Indium-deferoxamine labelled liposomes of the same composition. Liposomes were cleared predominantly by liver and spleen and to a lesser extent by bone marrow in seven out of nine patients. In two patients with active hepatitis and severe liver dysfunction, there was minimal liver uptake and increased spleen and bone marrow uptake. Except for one hepatoma patient, intrahepatic and extrahepatic tumours were not imaged by liposomes, suggesting that liposome uptake is restricted to cells of the reticulo-endothelial system (RES).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effect of major axial skeleton trauma on preexisting lumbosacral spondylolisthesis.

The incidental occurrence of lumbar spine fractures in individuals with preexisting first degree lumbosacral isthmic spondylolisthesis may be looked upon as a simulated in vivo biomechanical experiment testing the stability of the lumbosacral subluxation. Among 200 patients with thoracolumbar spine fractures managed at the author's institution during the period of 1980-1989, five such cases were collected. All patients had a grade I isthmic spondylolisthesis at the L5-S1 level, and all sustained a burst fracture of the lumbar spine. In two patients, there was a previous history of low back pain and lumbosacral spondylolisthesis. In the other three patients, the olisthesis was judged to be old by a negative 99mTc-MDP bone scan, whereas the fractured vertebra showed intense uptake and/or by the negative operative findings at L5-S1 level during surgery. It was found that the incidence of lumbosacral spondylolisthesis in patients with thoracolumbar fractures was smaller than in the general population but the difference was not statistically significant (p = 0.213). In addition, it is concluded that mild lumbosacral spondylolisthesis can absorb considerable axial loading without an ascertainable evidence of damage.

Adult↗
PubMed1990

Correlations between uptake of technetium, calcium, phosphate, and mineralization in rat tibial bone repair.

Technetium-99m-(99mTc) phosphates are extensively used for detection of bone formation and resorption. The present is a study of 99mTc incorporation during bone remodeling. Uptake of 99mTc-labeled phosphate was studied in an animal model of primary osteogenesis following tibial marrow injury and incorporation was correlated to that of calcium-47 (47Ca), phosphorus-32 (32P), and with matrix vesicle calcification. Isotope uptake on Day 6 in the whole bone was increased compared to controls. On this day, an increase in vesicular diameter and distance from the calcified front was previously observed. Technetium-99m-labeled phosphates were detected only in the organic phase. Phosphorus-32 and 47Ca were detected in both organic and inorganic phases. It is suggested that 99mTc serves as a specific marker to the anabolic phase of remodeling. Increased incorporation of 99mTc during bone healing indicates enhanced organic matrix formation and not calcification.

Animals↗
PubMed1989

Proton therapy for carcinoma of the nasopharynx: a study in comparative treatment planning.

Radiation therapy for nasopharyngeal carcinoma is technically difficult because of the complexity of the regional anatomy and the natural history of the disease. The results of a study are presented showing how detailed diagnostic information available from MRI is helpful in defining the target volume to be irradiated and the critical normal structures. By using 3-dimensional planning techniques, an assessment was made of the relative merits of proton beam therapy and of X ray treatment for patients with early stage and locally advanced carcinoma of the nasopharynx. For both types of patient, the study suggests that the use of protons for the major part of treatment results in a more even distribution of dose to the tumor and an increase of approximately 5 Gy in median tumor dose with substantial reductions in doses to adjacent normal tissues. The superior dose distributions possible with protons should translate into improved local control and reduced morbidity. The difficulties of proton treatment planning for this site are addressed.

Adult↗
PubMed1989

The effect of pretraining sports activity on the incidence of stress fractures among military recruits. A prospective study.

In a prospective study of stress fractures among Israeli infantry recruits, no correlation was found between the recruits' prior participation in sports activities or their aerobic physical fitness and the incidence of stress fractures during basic training. This finding discredits the concept that improving physical fitness prior to basic training can be a prophylactic means of limiting the incidence of stress fractures during subsequent training.

Adult↗
PubMed1988

99mTc-MDP uptake and histological changes during rat bone marrow regeneration.

An established experimental model of tibial bone regeneration in rats was used in order to try to provide further information on the binding site of 99mTc-MDP, which is still not clearly defined. Four groups of rats on which surgical tibial bone marrow evacuation was performed and two control groups (nonoperated animals and sham-operated animals) underwent bone scan during the different stages of marrow regeneration; they were killed immediately after, and histological examination carried out. The correlation between the scintigraphic and the histological findings suggests that 99mTc-MDP binds primarily to calcification sites in young bone trabecules.

Animals↗
PubMed1988

The clinical value of quantitative dynamic scintigraphy in salivary gland disorders.

Salivary gland scintigraphy with [99mTc]pertechnetate was performed in a group of 11 subjects without any known salivary pathology, and in a group of 12 xerostomic patients. Time-activity curves, normalized to background, were generated for each of the four major salivary glands in both groups, and averaged into single curves, representing the function of each gland. Comparing the two sets of curves (patients vs controls) demonstrates that utilizing our "normalization" approach enables one not only to determine whether one group of dynamic curves is significantly different from another, but to decide which of the glands are normal and which are malfunctioning. The sensitivity, specificity, accuracy and predictive values of this procedure are all above 0.90.

Adult↗
PubMed1988

Bone scintigraphic findings in recruits after short periods of nonweight-bearing ambulation. A report of two cases.

Two military recruits with suspected stress fractures underwent scintigraphy after brief periods of nonweight-bearing ambulation. Their scans showed a dramatic, diffuse increase of activity over the asymptomatic weight-bearing foot, with areas of increased focal activity. Our reported cases illustrate how gait changes can be reflected in scintigraphy and the difficulty in evaluating areas of increased focal scintigraphic activity in the feet. The physician should see the bone scan and not rely on a written report when evaluating a trainee for possible stress fracture.

Achilles Tendon↗
PubMed1987

Stress fractures and tibial bone width. A risk factor.

A prospective study of 295 infantry recruits has shown that the mediolateral width of the tibia measured radiographically at each of three different levels in the bone had a statistically significant correlation with the total incidence of stress fractures as well as with those in the tibia alone or the femur alone. A narrow tibial width was shown to be a risk factor, but cortical thickness was not found to be significant.

Femoral Fractures↗
PubMed1987

Clinical significance of nonfocal scintigraphic findings in suspected tibial stress fractures.

The clinical significance of nonfocal increased uptake on skeletal scintigraphy in suspected tibial stress fractures is controversial, because it may represent either bone reaction to stress or a stress fracture in evolution. The scintigraphic evolution of areas of abnormal tibial activity, graded according to a 1 to 4 rating system and their corresponding clinical courses, were analyzed in 27 military recruits, as part of a prospective study. Disappearance of pain correlated with scintigraphic healing and increased pain with progression to stress fracture. Decreased or persistent pain had equivocal scintigraphic correlation. Eight of 14 nondiscrete scintigraphic lesions disappeared in spite of continuous training by the recruits; four such lesions, however, progressed to stress fractures. This uncertainty of progression suggests that military recruits and people training for sports who have such scintigraphic activity should have a brief rest period and proper monitoring before resuming training.

Adolescent↗
PubMed1987

Can tinnitus mask hearing? A comparison between subjective audiometric and objective electrophysiological thresholds in patients with tinnitus.

Very little has been written in the literature about the masking effect of tinnitus on hearing. This possibility arose from the clinical observations of hearing fluctuating with the intensity of tinnitus. To explore this hypothesis, a group of 19 patients suffering from hearing loss and tinnitus underwent a complete audiological evaluation and their audiometric and ABR thresholds were compared. Two other groups who were examined in the same manner, served as control groups. The first group consisted of 19 age- and sex-matched subjects with relatively normal hearing and no tinnitus. The second control group was composed of 8 patients suffering from sensorineural hearing loss without tinnitus. The differences between the subjective and ABR thresholds within each group and between the groups were statistically analyzed. The objective thresholds in the tinnitus group were found to be lower than the subjective thresholds.

Adult↗
PubMed1987

External rotation of the hip. A predictor of risk for stress fractures.

External rotation of the hip was found to have a statistically significant correlation with the incidence of stress fractures, in a prospective study among Israeli infantry recruits of possible anthropomorphic predictors of risk for stress fractures. Soldiers in whom hip external rotation was greater than 65 degrees were at a higher risk for tibial and total stress fractures than those with external rotations of less than 65 degrees. The mean hip external rotation in this study of 57 degrees +/- 9.3 degrees was higher than in statistics reported in the American literature. The existence of a larger subpopulation with hip external rotation greater than 65 degrees may partially explain why the reported incidence of stress fractures in the Israeli army is higher than that of the American army.

Adolescent↗
PubMed1986

Stress fractures of the medial femoral condyle.

Three military recruits who presented with medial joint line pain and positive Appley grinding tests were found on the basis of scintigrams plus arthroscopy and/or arthrogram to have no intra-articular pathology, but rather medial femoral condyle stress fractures. The importance of the differential diagnosis is emphasized.

Adolescent↗
PubMed1986

Recurrent stress fractures in military recruits. One-year follow-up of 66 recruits.

Of 66 recruits who sustained stress fractures during basic training and returned to training after a period of rest, seven (10.6%) suffered recurrent fractures within one year. None of the recurrences was at the original anatomical site. All of the recruits with recurrent stress fractures had had at least one of their initial stress fractures in the femur. This suggests that a femoral stress fracture carries a high risk of recurrence at other sites.

Adult↗