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PubMed1984

Functional and morphological studies on isolated Leydig cells: purification by centrifugal elutriation and metrizamide fractionation.

Rat interstitial cells were fractionated by centrifugal elutriation to facilitate the purification of Leydig cells for analysis of mechanisms of gonadotropin action in vitro. By this procedure, 10(9) collagenase-dispersed interstitial cells from adult rat testes were separated into 12 fractions in about 1 h. Fractions 1-7 (sedimentation velocities, 1.9-12 mm/h.g) comprised 80-85% of the total cells applied, including erythrocytes, lymphocytes, germinal cells, macrophages, endothelial cells, damaged Leydig cells, and contained less than 4% intact Leydig cells. Fractions 8-12 (sedimentation velocities, greater than 12 mm/h.g) comprised 15-20% of the original cells and contained 90-95% intact Leydig cells. Despite their different sedimentation velocities, the Leydig cell-rich fractions were similar in their LH receptor content (mean +/- SD, 36,115 +/- 4,815 sites/cell) and showed similar 5-fold increases above the original cell preparation in testosterone and cAMP responses to hCG. The pooled Leydig cell-rich fractions (8-12) were further resolved on 16-24% Metrizamide gradients into 5 bands. Bands II-V (density range, 1.075-1.110 g/ml) contained pure Leydig cells, and band I (1.048 g/ml) contained pachytene spermatocytes, the contaminating cell type present in the Leydig cell-rich fractions obtained by elutriation. Each of the 4 Leydig cell-rich bands showed similar morphology and functional activity. Essentially similar results were observed using 14-32% Metrizamide gradients. Leydig cells desensitized in vivo by hCG treatment and isolated by elutriation were also resolved by Metrizamide gradients into 4 bands, but showed a redistribution in the gradient, due to the shift of about 50% of the cells originally present in the heaviest bands to lower density fractions. However, in spite of their changes in density, the Leydig cell bands still showed similar degrees of receptor down-regulation and impairment of the steroid responses to hCG in vitro. This study has demonstrated that centrifugal elutriation is a rapid and effective method for obtaining large quantities of purified (greater than 90%) and active Leydig cells. Further resolution of the Leydig cell-rich fractions in Metrizamide gradients has allowed complete Leydig cell purification, which is not achieved by density gradient centrifugation alone. Since less responsive or inactive Leydig cells displayed various degrees of structural damage, such cells should not be considered as a population of physiological significance.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1981

Lateral and third-ventricular CSF formation after metrizamide CT ventriculography.

We calculated the rates of lateral and third-ventricular (LTV) cerebrospinal fluid (CSF) formation in three patients undergoing metrizamide computed tomography (CT) ventriculography with reference to Ct estimates of ventricular volume and the time course of LTV metrizamide washout (elimination). Elimination rate constants for metrizamide were derived from measurements of LTV metrizamide concentration on serial postventriculography CT scans, and LTV volumes were estimated by partial volume analysis. CSF formation in the combined lateral ventricles averaged 0.14 ml per minute, and third-ventricular CSF formation averaged 0.014 ml per minute. Thus, the third ventricle accounted for approximately 10% of total LTV CSF production, which accords with relative weights of choroid plexus tissue in the lateral and third ventricles.

Adult↗
PubMed1984

Iohexol versus metrizamide for lumbar myelography: preliminary report of double-blind trial.

Lumbar myelography was performed in 38 patients; 19 received iohexol (an investigational aqueous contrast agent) and 19 received metrizamide. Iohexol is stable in solution, which is not the case with metrizamide. There was no other significant difference in diagnostic utility or quality between the two media. However, there was considerable postmyelography morbidity in the metrizamide group, but no postmyelography morbidity in the iohexol group. Preliminary clinical evidence suggests that iohexol is significantly superior to metrizamide as a contrast agent for lumbar myelography.

Adult↗
PubMed1976

Lumbar myelography with metrizamide-a new non-ionic contrast medium.

In contradistinction to all currently available water-soluble contrast media, metrizamide (Amipaque) is not a salt, but a substituted amide and therefore does not dissociate in solution. This unique property results in solutions of high iodine content yet with low osmolality. Metrizamide probably has a lower neurotoxicity than any other known water-soluble contrast agent. A clinical trial of metrizamide lumbar myelography in 201 patients in three clinical centres represents the first clinical assessment of this new contrast medium in the United Kingdom. The technique of the radiological procedure and the adverse reactions encountered are presented and discussed. There were no serious adverse effects: no muscle spasm or epilepsy. Minor adverse reactions--headache, vomiting and nausea occur with approximately the same frequency as with meglumine iocarmate: 43 percent of patients complained of headache. In 118 patients, the lower dorsal subarachnoid space was also examined with no increase in toxic reactions. It is concluded that metrizamide is a safe contrast medium for lumbar and lower dorsal myelography. Water-soluble media will probably largely replace oil products for these investigations. Further clinical trials are being extended to include examination of the upper dorsal and cervical subarachnoid space.

Arachnoiditis↗
PubMed1981

Accurate CT measurement of the spinal cord using metrizamide: physical factors.

Computed tomography (CT) using metrizamide is a valuable tool in the neuroradiologic evaluation of the spinal cord, but CT must be used with care when measuring object size because size may vary with different window center (level) settings. A simple method to determine appropriate window center (level) settings during CT object measurement is described. A polystyrene core with a Teflon outer cylinder designed to simulate the spinal column, spinal cord, and subarachnoid space was scanned with varying concentrations of metrizamide with an EMI 1010 unit. Computer printouts of the CT pixel matrix were analyzed and a constant relationship of the phantom cord true size to the CT numbers of the metrizamide concentration and the phantom spinal cord was found. Window center (level) selection greatly influences measurement of cord size, whereas window width dose not. The appropriate window center (level) selection is the mean between the metrizamide CT attenuation number and the cord CT attenuation number.

Evaluation Studies as Topic↗
PubMed1983

Comparative hemodynamic effect of metrizamide and Renografin 76 in infants with congenital heart disease.

Twenty patients under the age of 2 years with suspected congenital heart disease received alternately Renografin 76 and metrizamide for angiocardiography. The dose was 2.0 ml/kg per injection for both contrast media into the left ventricle. Metrizamide induced slightly lesser change in heart rate, peak systolic pressure, and peak end-diastolic pressures. Serum osmolality, hematocrit, and serum electrolytes were affected equally by the contrast media. Metrizamide was well tolerated by the neonates with congenital heart disease and its radiopacity was adequate for diagnostic purposes. At the doses administered, metrizamide does not seem to have any great advantage over Renografin 76 for angiocardiography in infants with severe congenital heart disease.

Angiocardiography↗
PubMed1984

Intraoperative spinal sonography: adjunct to metrizamide CT in the assessment and surgical decompression of posttraumatic spinal cord cysts.

Ten patients with prior spinal cord trauma were examined preoperatively by metrizamide computed tomography (CT) and were studied subsequently by intraoperative spinal sonography. On comparing intraoperative sonography with metrizamide CT, it was found that metrizamide CT tends to overestimate the size and number of posttraumatic cysts, that areas of myelomalacia on metrizamide CT correspond to areas of abnormal echogenicity on intraoperative sonography, and that intracyst septations are seen only on intraoperative sonography. By monitoring the position of the shunting catheter during surgery, intraoperative sonography can assure its proper intramedullary placement and demonstrate the successful decompression of the cyst. If no cyst is found with intraoperative sonography, further surgery is obviated. Intraoperative sonography is recommended for all cases where decompression of cord cysts is planned.

Cysts↗
PubMed1986

Cognitive and affective changes after myelography: a comparison of metrizamide and iohexol.

A battery of brief cognitive tests and a mood scale were administered to 42 patients before and after cervical myelography with either metrizamide (20 patients) or iohexol (22 patients). The patients receiving metrizamide experienced a deterioration in mood after myelography and a relatively greater decline in cognitive test performance than did those receiving iohexol. These two side effects tended to occur together in the metrizamide group, suggesting a common underlying cause; but there was no correlation between changes in mood and cognitive function after myelography with iohexol. These results suggest that metrizamide has a greater neurotoxic effect than iohexol.

Adult↗
PubMed1977

A comparison of a new non-ionic (metrizamide) and a dissociable (metrizoate) contrast medium in endoscopic retrograde pancreatography (ERP).

Endoscopic retrograde pancreatography (ERP) was performed on 12 patients with a non-ionic contrast medium (metrizamide) and a traditional dissociable medium (metrizoate). All patients were examined with both media at an interval of one week. The study was based on double blind and a cross-over randomization. There was a significantly lower rise in serum amylase 2 (p = 0.05), 4 (p = 0.04), and 6 hours (p = 0.03) after the examination using the non-ionic contrast medium than after using a dissociable one. The pain during contrast filling of the pancreas was significantly lower (p = 0.015) when using metrizamide than when using metrizoate. All, except one patient, preferred the examination with the non-ionic contrast medium (p = 0.0002). A positive correlation was found between pain and degree of pancreatic filling when using the dissociable medium (r = 0.77). Such a correlation could not be detected following the non-ionic contrast medium (r = 0.009). There was a positive correlation between rise in serum amylase and degree of pancreatic filling with both contrast media. The coefficient of correlation was lower after metrizamide (r = 0.21) than after metrizoate (r = 0.56). It is concluded that a non-ionic contrast medium in this study was better tolerated than a dissociable medium, and that metrizamide was more suitable for endoscopic retrograde pancreatography than the traditional hypertonic contrast medium.

Adult↗
PubMed1984

Evaluation of cervical spinal cord injuries with metrizamide myelography-CT scanning.

In the past, patients with injuries of the cervical spine and spinal cord have been diagnosed by means of myelography and polytomography. In an attempt to improve the radiographic evaluation of patients with cervical spinal cord injuries the authors performed computerized tomography (CT) scanning of the cervical spine following injection of metrizamide into the spinal subarachnoid space. In 23 patients with cervical spinal cord injuries, metrizamide myelography was performed via a C1-2 puncture. Myelography was used only for localization of the lesion and to determine the site of CT scanning. After myelography, CT scanning of the cervical spine in the transaxial plane was effective in determining the exact nature of compressive lesions and distinguishing the etiology among hematoma, disc, bone fragments, osteophytes, or ossification of the posterior longitudinal ligament. In several patients, metrizamide could be seen entering the spinal cord and was indicative of anatomical spinal cord disruption. In patients with fractures, CT scanning identified the site and nature of the injury without the need for turning the patient to the lateral position. In several patients with an apparently stable cervical spine, the CT scan showed apophyseal joint widening indicative of instability. The authors conclude that CT scanning of the cervical spine after the introduction of metrizamide into the subarachnoid space provides a definitive evaluation of the cervical spinal cord, the bone structures of the cervical spine, and their relationship to each other.

Adolescent↗
PubMedDate not supplied

Metrizamide in experimental urography. IV. Effects of bilateral ureteric stasis on urine iodine concentration after intravenous infection of an ionic and a non-ionic contrast medium.

The non-ionic contrast medium metrizamide was compared to the sodium salt of diatrizoate to investigate the potential usefulness of metrizamide in clinical urography when ureteric stasis is applied. After intravenous injection of the contrast media to rabbits at dose level 175 mg I/kg, the kidneys were subjected to temporary bilateral ureteric stasis. Urine was collected through ureteric catheters and analyzed for its concentration of iodine, sodium and potassium. After metrizamide injection the urine iodine concentration was twice as high as after sodium diatrizoate injection. This difference between one non-ionic and one ionic contrast medium was larger than what has been reported earlier during free flow of urine at the same dose. Furthermore, during the periods of ureteric stasis metrizamide was excreted faster than diatrizoate. When diatrizoate was given as its sodium salt, the sodium given was excreted at about the same rate as the diatrizoate given.

Animals↗
PubMed1992

Cerebrospinal fluid changes after iopamidol and metrizamide myelography in clinically normal dogs.

Cerebrospinal fluid samples from 2 groups of clinically normal dogs were compared after iopamidol (n = 9) and metrizamide (n = 8) myelography. Iopamidol (200 mg of I/ml) and metrizamide (170 mg of I/ml) were administered by cerebellomedullary injection at dosage of 0.45 ml/kg of body weight. In dogs of both groups, postmyelographic CSF changes included high specific gravity, Pandy score, protein concentration, and WBC count. The high specific gravity and Pandy score were false-positive effects attributed to nonionic contrast media. Although postmyelographic protein concentration and total WBC count were greater in CSF samples from dogs given metrizamide than in those given iopamidol, differences were not statistically significant. The differential WBC counts were consistent with mild, acute leptomeningitis; these findings were supported by results of histologic examination. Iopamidol and metrizamide should be considered low-grade leptomeningeal irritants in dogs.

Animals↗
PubMed1986

The effect of subarachnoid metrizamide and iohexol on cerebral glucose metabolism in vivo.

We studied the effect of metrizamide and iohexol on local cerebral glucose utilization (LCGU) using autoradiography. Metrizamide or iohexol was introduced into the subarachnoid space of rabbits and positioned over the right hemisphere for 3 or 6 hours. Using the unexposed (left) hemisphere as an internal control, we calculated relative changes in LCGU. In the three metrizamide-exposed animals the LCGU was decreased over the contrast media-exposed right temporoparietal cortex (L-R difference was positive). There was no significant changes in LCGU and no positive L-R difference after treatment with iohexol (three animals). We conclude that metrizamide does affect glucose metabolism in vivo, and this effect is dependent on localization of the contrast medium. The clinically safer drug, iohexol, in similar concentration and higher osmolality, did not decrease glucose metabolism.

Animals↗
PubMed1977

Metrizamide brain penetrance.

The normal cerebrospinal fluid flow as monitored by serial CT cisternography with metrizamide (Amipaque) is described in 25 individuals. Preliminary gross autoradiography using 131I-labelled metrizamide concur with these CT cisternographic findings indicating that intrathecally introduced metrizamide penetrates the brain substance. Adverse reactions are most prominent during the periods of maximum brain penetration and include headache, nausea, perceptual aberrations, and EEG alterations. The value and diagnostic applications of cerebral and cerebellar penetration of metrizamide are also discussed.

Animals↗
PubMed1988

Risk of seizures after myelography: comparison of iohexol and metrizamide.

A parallel, double-blind, randomized study comparing iohexol and metrizamide--both 180 mg l/ml--in lumbar myelography was carried out in 60 consecutive patients. Eight to 15 ml of contrast medium were administered with the upper level at the middle thoracic column. A detailed neurologic examination was performed before and 24 hr after myelography. EEG recordings--evaluated visually and with fast Fourier transformation analysis--and somatosensory evoked responses were registered before, 6 hr after, and 24 hr after myelography. All patients were observed for adverse reactions for 24-48 hr. Iohexol did not produce any epileptiform activity but epileptiform activity was detected in five patients receiving metrizamide. Iohexol produced significantly less frequent and less severe EEG changes than did metrizamide both at visual evaluation (p less than .0025) and at fast Fourier transformation analysis (p less than .04). No significant changes occurred in the early components of the somatosensory evoked potentials after either contrast medium. Iohexol caused significantly (p less than .002) less frequent and less severe adverse reactions than did metrizamide. The neurologic examination revealed no changes of clinical importance with either contrast agent.

Double-Blind Method↗
PubMed1977

Angiography with metrizamide. Animal experiments and preliminary clinical experiences.

The non-ionic contrast medium metrizamide (Amipaque) was compared in animal experiments with diatrizoate, iothalamate and metrizoate. Vasodilatory effects, acute intravenous toxicity and effects on red blood cells, pulmonary arterial pressure, endothelium and heart were all less after metrizamide than after the ionic media. This motivated clinical trial of metrizamide for angiography, which demonstrated that metrizamide produced less pain than the ionic monomeric media in femoral as well as in other types of angiography.

Animals↗
PubMed1979

A short survey on experimental studies with relevance to vascular use of metrizamide.

Metrizamide was originally developed for application in the subarachnoid space. Later the contrast medium was tested for angiographic possibilities in extensive animal experiments. The effects of metrizamide, as examined successively on the kidneys, liver, lungs and heart, were compared with those of ionizing contrast media. The effect of metrizamide on the kidneys and liver proved similar to those of the ionizing contrast media but the toxic action of metrizamide on the remaining organs was found to be smaller.

Angiography↗
PubMedDate not supplied

Iopamidol vs. metrizamide myelography: clinical comparison of side effects.

One hundred myelographies with iopamidol and 100 with metrizamide were performed in order to compare the side effects of the two contrast media after injection into the spinal subarachnoid space. All patients were observed for a follow-up period of at least 4 days. The most frequently observed side effect, headache, was more common, of longer duration, and more severe with the use of metrizamide than with iopamidol. Only neck pain was more common with iopamidol. More severe side effects such as meningeal irritation, psychoorganic syndrome, and epileptic seizures occurred only with metrizamide. The results seem to indicate a lower neurotoxicity and better patient tolerance for iopamidol than for metrizamide.

Adult↗