11C-acetate PET in the evaluation of brain glioma: comparison with 11C-methionine and 18F-FDG-PET.

PURPOSE: The aim of the study is to retrospectively investigate the usefulness of 11C-acetate (ACE)-positron emission tomography (PET) for evaluation of brain glioma, in comparison with 11C-methionine (MET) and 2-deoxy-2-18F-fluoro-D-glucose (FDG). PROCEDURES: Fifteen patients with brain glioma referred to initial diagnosis were examined with ACE, MET, and FDG-PET. Five patients had low-grade gliomas (grade II), three had anaplastic astrocytomas (grade III), and seven had glioblastomas (grade IV). PET results were evaluated by visual and semiquantitative analysis. For semiquantitative analysis, the standardized uptake value (SUV) and tumor to contralateral normal gray matter (T/N) ratio were calculated. The sensitivity for detection of high-grade gliomas was calculated using visual analysis. RESULTS: Sensitivities of ACE, MET, and FDG were 90%, 100%, and 40%, respectively. ACE and MET T/N ratios were significantly higher than that of FDG. ACE and FDG SUV in high-grade gliomas were significantly higher than that in low-grade gliomas. No significant differences were observed using MET. CONCLUSIONS: ACE PET is a potentially useful radiotracer for detecting brain gliomas and differentiating high-grade gliomas.

Karyotypic changes from initial diagnosis to relapse in childhood acute leukemia.

Cytogenetic study was performed at both diagnosis and relapse in 31 children with acute leukemia who had initially abnormal karyotypes, 21 with acute lymphocytic leukemia (ALL) and 10 with acute nonlymphocytic leukemia (ANLL). Seventy percent of the patients showed karyotypic changes between diagnosis and relapse. The ALL patients showed karyotypic changes more often than the ANLL patients (76 vs. 40%)(chi-square test, p less than 0.05). All the initially abnormal patients with karyotypic changes exhibited structural changes, most frequently chromosome 1 abnormalities, especially in ANLL, and 6q-, 7p-, 9p- in ALL. Half of the patients, with structural karyotypic change had two or more clonally related cell lines at relapse. On the other hand, only 20% of the patients with karyotypic changes showed numerical changes. All but one of the initially abnormal patients showed karyotypic changes involving the original cytogenetically abnormal clone. Our study demonstrated that sequential cytogenetic studies may provide a better understanding of the nature of leukemia relapse.

Birth of mice after in vitro fertilization using C57BL/6 sperm transported within epididymides at refrigerated temperatures.

The transportation of cryopreserved spermatozoa is an economical, efficient, and safe method for the distribution of mouse strains from one facility to another. However, spermatozoa from some strains, including C57BL/6 (B6), are very sensitive to freezing and thawing and frequently fail to fertilize eggs by conventional in vitro fertilization methods at the recipient mouse facility. Since many genetically engineered mice have the B6 genetic background, this sensitivity poses a major obstacle to studies of mouse genetics. We investigated the feasibility of transporting spermatozoa within epididymides under non-freezing conditions. First, we examined the interval that B6 and B6D2F1 (BDF1) spermatozoa retained their ability to fertilize when stored within epididymides at low temperatures (5 degrees C or 7 degrees C). Fertilization rates were >50%, irrespective of the spermatozoa used, when epididymides were stored for 3d at 7 degrees C. B6 spermatozoa, but not BDF1 sperm, had better retention of fertilizing ability at 7 degrees C versus 5 degrees C. We then transported freshly collected B6 and BDF1 epididymides from a sender colony to a recipient colony using a common package delivery service, during which the temperature was maintained at 5 degrees C or 7 degrees C for 2d. Sufficiently high fertilization rates (68.0-77.5%) were obtained for all experimental groups, except for B6 spermatozoa transported at 5 degrees C. These spermatozoa were successfully cryopreserved at the recipient facility and, yielded post-thaw fertilization rates of 27.6-66.4%. When embryos derived from the B6 spermatozoa that were transported at 7 degrees C were transferred into recipient females, 52.7% (38/72) developed to term. In conclusion, transportation of epididymides at refrigerated temperatures is a practical method for the exchange of mouse genetic resources between facilities, especially when these facilities do not specialize in sperm cryopreservation. For the B6 mouse strain, the transportation of epididymides at 7 degrees C rather than 5 degrees C, is recommended.

Fast and slow recovery phases of goldfish behavior after transection of the optic nerve revealed by a computer image processing system.

As the goldfish is a common experimental animal for vision research, including psychophysical behavior, it is very important to quantitatively score fish behavior. We have previously developed a computer image processing system which can acquire the positional coordinates of goldfish moving freely in an aquarium and determine turning directions (go straight, right or left turn). In the present study, an algorithm to determine tilting angles of moving goldfish was constructed. We also made histograms for quantifying the interaction between pairs of goldfish (two-point distance). By using these histograms, we estimated the time-course of behavioral regeneration after optic nerve transection in goldfish. Control goldfish showed an equal percentage of right or left turns and maintained an upright position in a dorsoventral axis. When the optic nerve of a goldfish was unilaterally sectioned, the goldfish showed predominant turning and slight tilting toward the intact eye. The abnormal turning and tilting behaviors lasted for 10-14 days and then gradually decreased, returning to control behaviors by one month after the unilateral transection. When the optic nerve of a single goldfish was bilaterally sectioned, it did not show any preferential turning and tilting behavior, which is similar to what was observed in control goldfish. However, the trace maps showed that, after bilateral sectioning, fish preferred to cross the center of the tank, which was unlike control fish. In control pairs, one goldfish chased the other with a fixed small range of two-point distances. However, in pairs of goldfish with bilateral transection of the optic nerve, the blind goldfish behaved independently of each other, with a long two-point distance. The long two-point distance of the blind goldfish lasted for at least two months and then slowly returned to control two-point distance by four months after bilateral transection. Such fast and slow recovery in goldfish behaviors evoked after unilateral and bilateral transection of the optic nerve is discussed with respect to reconnection of regenerating optic nerves in the fish central nervous system. This computer image processing system is a useful tool with which we can quickly and easily quantify fish behavior.

Glutathione depletion causes an uncoupling effect on retinal horizontal cells through oxidative stress.

To investigate a physiological role of glutathione in the horizontal cells of carp retina, the gap junctional intercellular communication between horizontal cells was studied using the techniques of intracellular recording of light-induced responses and coupling of the fluorescence dye Lucifer Yellow. Intravitreal injection of 2.5 micromol L-buthionine sulfoximine, an inhibitor of glutathione synthesis, induced a dramatic reduction (20% of control) of retinal glutathione level two days after treatment. The low level of glutathione continued for a further four to five days, and thereafter gradually recovered to about 40% (20 days after injection) and 70% (50 days after injection) of the control level. The spatial properties of the photopic L-type horizontal cell response were examined by enlarging the diameter of the central spot and peripheral annulus over the recording point. In normal retinas, the response amplitude of horizontal cells was monotonically enhanced as the diameter of the spot increased (0.5-4.0 mm) and correspondingly the dye diffusion area was wide, as the injected Lucifer Yellow normally diffused to several neighboring cells. Treatment with L-buthionine sulfoximine significantly altered the spatial properties of horizontal cells by increasing the response amplitude to central spots and slightly decreasing that to peripheral annuli, which were observed by four days after injection. It also restricted intracellular Lucifer Yellow to one or two cells. Accompanying the recovery of the cellular level of glutathione, the spatial properties and dye coupling of horizontal cells were restored to normal. A time lag (two days) of initiation in retinal glutathione depletion and alteration of spatial or dye coupling properties of horizontal cells is discussed, together with reactive oxygen species accumulation.

Technetium-99m-MIBI and thallium-201 scintigraphy of primary lung cancer.

UNLABELLED: We evaluated the usefulness of 99mTc-MIBI scintigraphy in primary lung cancer in comparison with 201Tl-chloride scintigraphy. METHODS: There were 45 patients with primary lung cancer. All patients underwent dual-isotope imaging with 201Tl-chloride and 99mTc-MIBI. Regions of interest were placed over the tumors (T) and contralateral normal lung tissue (N) on one coronal view in the SPECT, and T/N ratio and retention index were calculated. RESULTS: The positive rate was 98% in both the early and delayed images for 201Tl-chloride and 96% in the early and 89% in the delayed image for 99mTc-MIBI. Both early and delayed T/N ratios for 201Tl-chloride were higher than those for 99mTc-MIBI. There was no significant correlation between T/N ratio and histological type of tumor in both images. However, in both images, there was a tendency for the early and delayed ratios to increase as the tumor diameter became larger. The retention index of 201Tl-chloride was higher than that of 99mTc-MIBI. There were no significant differences in the retention index with respect to the histological type and tumor size. CONCLUSION: The results of this preliminary clinical study suggest that 99mTl-MIBI can depict primary lung cancer similar to 201Tl-chloride. However, T/N ratio and retention index of 99mTc-MIBI in the tumor areas are significantly lower compared with those of 201Tl-chloride.

Visualization of the motor activation area using SPECT in neurosurgical patients with lesions near the central sulcus.

UNLABELLED: The purpose of this study was to visualize the motor area related to finger movement and a fist-making task using SPECT in patients with lesions near the central sulcus. METHODS: Eleven patients (9 with a brain tumor, 1 with cerebral infarction, and 1 with an arteriovenous malformation) were investigated. The first intravenous injection of 99mTc-ethyl cysteinate dimer (ECD) for the motor activation SPECT images was administered 2 min after completion of the fist-making task with the hand contralateral to the brain lesion. The movement was stopped 2 min after injection, and activation SPECT was performed. After the scan, the second dose of 99mTc-ECD was injected into resting patients, and a second set of SPECT images was acquired. The first set of images was subtracted from the second set to obtain control images. Regions of interest were set bilaterally on the sensorimotor hand area; the supplementary motor area; the frontal, temporal, and occipital lobes; and the cerebellar hemispheres. The results of activation SPECT were expressed as positive or negative for a high-count area, and the regional percentage change for activation images relative to resting images was calculated. RESULTS: Visual assessment of activation images was positive in 9 patients for the sensorimotor hand area and 7 patients for the supplementary motor area. The regional percentage change between activation and resting images for the high-count areas was 19.7% for the sensorimotor hand area and 18.2% for the supplementary motor area. Both values were significantly higher than those for other areas (P<0.05). CONCLUSION: Motor activation SPECT using a 99mTc-ECD split-dose method is easy to perform and may be helpful for presurgical visualization and identification of the sensorimotor hand area or the supplementary motor area.

Comparative study of technetium-99m-sestamibi and thallium-201 SPECT in predicting chemotherapeutic response in small cell lung cancer.

UNLABELLED: The purpose of this study was to evaluate the relationship between 99mTc-sestamibi (MIBI) accumulation by tumor and response to chemotherapy in small cell lung cancer patients compared with 201TI-chloride. METHODS: There were 19 patients with small cell lung cancer just before chemotherapy initiation. The patients were classified by a follow-up CT into complete remission, partial remission and no change groups. All patients underwent dual-isotope imaging with 201TI-chloride and 99mTc-MIBI. Regions of interest were placed over the tumors and contralateral normal lung tissue on one coronal view with a clearly defined lesion, and the tumor-to-normal (T/N) ratio and retention index were calculated. RESULTS: Early and delayed T/N ratios for 99mTc-MIBI in complete remission and partial remission groups were significantly higher (p < 0.05) than in the no change group. There was no significant correlation between T/N ratio and tumor response using 201TI-chloride. There were no significant differences in the retention index with respect to the tumor response in both 201TI-chloride and 99mTc-MIBI SPECT images. CONCLUSION: Technetium-99m-MIBI SPECT may be more effective than 201TI-chloride SPECT for evaluating response to chemotherapy in patients with small cell lung cancer.

CT assessment of subtypes of pulmonary emphysema in smokers.

OBJECTIVE: To determine the incidence of subtypes of pulmonary emphysema (PE) identified by CT imaging in male patients who have a significant smoking history. PATIENTS AND SETTING: We reviewed 945 subjects (619 men and 326 women) who had undergone CT scanning. However, only the data for male subjects were analyzed due to there being too few female subjects. The male subjects were divided into the following two age groups: group A (age, 50 years). There were two subtypes of PE found: centrilobular emphysema (CLE) and paraseptal emphysema (PSE). Based on these subtypes, PE was divided into the following three categories: I (CLE or CLE-predominant); II (CLE and PSE of equal extent); and III (PSE or PSE-predominant). RESULTS: PE was found in 270 of 516 male smokers (10 of 38 female smokers had PE). Among male subjects, in age group A there were 53 subjects with some degree of PE (category I, 12 subjects [22.6%]; category II, 7 subjects [13.2%]; and category III, 34 subjects [64.2%]). Among men in age group B, there were 217 subjects with some degree of PE (category I, 109 subjects [50.2%]; category II, 23 subjects [10.6%]; and category III, 85 subjects [39.2%]). CONCLUSION: In age group A, men < 50 years of age who were in category III (PSE or PSE-predominant PE) predominated (34 of 53 subjects; 64.2%). In age group B, men > 50 years of age who were in category I (CLE or CLE-predominant PE) predominated (109 of 217 subjects; 50.2%).

Colocalization of GP125/CD98 with tropomyosin isoforms at the cell-cell adhesion boundary.

Two monoclonal antibodies designated as 1F6 and 4B10 were obtained on screening for reactivities to CD98-associated molecules by sandwich-type enzyme-linked immunosorbent assaying using hybridoma culture supernatants as the solid phase, cell lysates as an antigen source, and a mixture of biotinylated antibodies to CD98HC as a detector. Flow cytometric analysis with microspheres in combination with 1F6, 4B10, and anti-CD98HC also indicated the association of antibody-defined antigen(s) with CD98. 1F6 and 4B10, stained fibrillate components in fixed and permeated cells but were not reactive with unfixed live cells, suggesting that epitopes reside in the cytoskeleton-associated structure in the intracellular region. Two-color immunostaining followed by confocal microscopy revealed the colocalization of the antigen with CD98 at the cell-cell adhesion boundary of HeLa cells. 1F6 detected proteins with relative molecular masses of 33,000 to 43,000 on immunoblotting analysis involving cell lysates of human and rat cell lines. Analysis with a purified tropomyosin specimen from rabbit skeletal muscle demonstrated that 1F6 and 4B10 recognize tropomyosin. Two-dimensional gel electrophoresis followed by immunoblotting analysis revealed that 1F6 recognizes various tropomyosin isoforms. These results indicated that CD98 physically associates directly or indirectly with tropomyosin, and that this association is closely related to the cell-cell interaction.

Effects of regenerating liver cytosol on drug-induced hepatic failure.

Despite various interventions, the mortality rate after acute hepatic failure remains extremely high. Although it has been shown that administration of regenerating liver cytosol (RLC) after hepatic failure improves the survival rate of animals, the sequence in which various hepatic functions are altered after acute hepatic failure and their improvement by RLC remain unknown. To study this, fulminant hepatic failure in rats was produced by intraperitoneal injection of 1.5 gm/kg D-galactosamine (GAL). Twenty-four hours after 68% hepatectomy in normal rats, RLC was prepared and 4 ml of this solution (40 to 50 mg protein) was injected intraperitoneally in other animals at 6 or 24 hours after GAL administration. The long-term survival rate was 19.4% in the GAL-vehicle (control) group, 26.7% in the GAL-treated rats given liver cytosol from normal rats, and 72.2% (p less than 0.01 compared with both groups) in rats given RLC even 24 hours after GAL administration. Reticuloendothelial function was depressed at 24 and 48 hours after GAL administration; however, treatment with RLC but not vehicle or normal liver cytosol at 6 or even 24 hours after GAL administration significantly improved reticuloendothelial function 24 hours after GAL administration. DNA synthesis (an indicator of cell proliferation) did not increase in any group 24 hours after GAL administration; however, it increased strikingly at 48 hours in the GAL-RLC groups. Serum bilirubin levels were also lower in the RLC group 48 hours after GAL administration. Thus RLC administration improved survival, reticuloendothelial function, DNA synthesis, and hepatocyte function after GAL-induced acute hepatic failure. Improvement of reticuloendothelial function by RLC occurred before stimulation of DNA synthesis and appears to play an important role in improving survival after hepatic failure.

Re-evaluation of sexual dimorphism in human corpus callosum.

To study the sexual dimorphism of human corpus cauosum (CC), we analyzed the midsaggital magnetic resonance imaging (MRI) morphometry in 67 adults aged (mean+/-s.d.) 36.82+/-9.35 years. Four specific angles of the CC were determined. All four angles in 34 females and 33 age-matched males showed a significant difference between females and males. These morphometric findings confirm a gender difference in the orientation of corpus callosum.

Enuresis in an adult female with obstructive sleep apnea.

Adult onset enuresis accompanied by obstructive sleep apnea has been reported rarely. A female patient was referred to our clinic with complaints of of a 15-year history of loud snoring and sleep apnea as well as enuresis, which was treated successfully with imipramine and acetazolamide. The mechanism of enuresis and its relationship to upper airway obstruction are reviewed here with reference to the findings of polysomnography and sleep cystometry.

Doses of antibiotic in patients with renal insufficiency.

The pharmacokinetic properties of cefotaxime were studied in 30 subjects with various degrees of renal function after a single 1-gm intramuscular injection. Serum and urinary concentrations of cefotaxime and desacetyl cefotaxime were determined by high-pressure liquid chromatography. The pharmacokinetic parameters were obtained using a one-compartment open model. A significant (P less than 0.0001) linear correlation was demonstrated between the elimination rate constant of cefotaxime and creatinine clearance. The mean serum half-life of cefotaxime was 0.86 hour in normal subjects and was prolonged to 2.35 hours in hemodialysis patients. The mean 24-hour urinary recovery was 51.7% as cefotaxime and 25.6% as desacetyl cefotaxime in normal subjects. In the present study, modification of the dosage is probably unnecessary in patients with creatinine clearance of more than 30 ml/min; however, dose reduction or prolongation of dosage interval, or both, may be appropriate in patients with severe renal dysfunction.

Studies of effects of anticancer agents in combination with/without hyperthermia on metastasized human bladder cancer cells in chick embryos using the polymerase chain reaction technique.

Cultivated T24 cells derived from a human bladder cancer were inoculated into the chorioallantoic membrane vein of chick embryos. Hyperthermic treatment was performed following injection of anticancer agents 3 days after the inoculation of the T24 cells. DNA samples were obtained from the livers of the chick embryos, and the polymerase chain reaction technique was used to amplify a DNA fragment specific to the human beta-globin gene. The Southern hybridization method was used to evaluate the inhibitory effects of anticancer agents in combination with/without hyperthermia on T24 cells metastasized to the liver. The hyperthermia exerted an inhibitory effect on the growth of the T24 cells in the livers of the chick embryos, and this was dependent on the thermal dose. The antitumor effects of hyperthermia performed at 42.5 degrees C for 20 min and at 43.0 degrees C for 10 min were evidenced by 69.2% an 82.0% inhibition of the growth of the metastasized T24 cells, respectively, as compared with the growth of untreated T24 cell. Hyperthermia performed at 42.5 degrees C for 10 min alone produced 26.7% tumor growth inhibition, and these conditions for hyperthermia were subsequently used as a criterion for evaluating the effects of its combination with various anticancer agents. Adriamycin (20 micrograms/egg) alone, mitomycin C (10 micrograms/egg) alone, carboplatin (10 micrograms/egg) alone, and cisplatin (10 micrograms/egg) alone produced 13.5%, 58.9%, 27.3%, and 29.1% tumor growth inhibition, respectively. Adriamycin and mitomycin C applied in combination with hyperthermia showed additive inhibitory effects on the growth of the metastasized T24 cells in this chick embryo model.

Benign osteoblastoma of the temporal bone.

We report a case of benign osteoblastoma arising in the temporal bone of a 28-year-old woman. Plain radiography showed a mass with an amorphous calcified matrix and a thin radiolucent marginal zone. CT and MR imaging were useful in delineating the extent of the tumor, and angiography showed its hypervascularity. Preoperative transarterial embolization was effective in reducing bleeding during surgery.

Intraarterial infusion of papaverine in experimental cerebral vasospasm.

PURPOSE: To determine the effectiveness of intraarterial infusion of papaverine hydrochloride (PPV) in an experimental model of cerebral vasospasm and to measure the mean blood flow velocity of the middle cerebral artery (MCA). METHODS: Seven Japanese monkeys were divided into three groups: those studied 3 days-after surgery (the third-day group, n = 3); those studied 7 days after surgery (the seventh-day group, n = 3); and a control group (n = 1). Vasospasm was induced in the experimental groups by placing a blood clot in the subarachnoid space around the top of the internal carotid siphon. PPV (5 mg/kg) was infused (over 60 minutes) into the internal carotid artery (ICA). The vascular diameters of the ICA and MCA were measured on angiograms before and after infusion. The mean blood flow velocity in the MCA was measured on transcranial Doppler sonograms before and 24 hours after infusion. After fixation, the MCA was dissected out, stained, and examined microscopically. RESULTS: After vasospasm induction, both arteries were narrowed more than 30% in the third-day group and more than 50% in the seventh-day group. After PPV infusion in both groups, vascular dilatation of about 20% was seen. The mean increase in blood flow velocity in the third-day group (30%) was smaller than in the seventh-day group (70%). The mean blood flow velocity in the MCA decreased by about 30% in both groups, but increased again after 24 hours nearly to the level before PPV infusion. The intimal layer was more corrugated in the seventh-day group, and hypertrophy in the smooth muscle layer was also seen. Clinical examination showed no neurologic deficit in the third-day group 24 hours after PPV infusion; neurologic deficits were observed in the seventh-day group. CONCLUSION: PPV infusion may be more effective in early stages of vasospasm when vascular walls have fewer histologic changes.

Neonatally administered diethylstilbestrol retards the development of the blood-testis barrier in the rat.

Newborn rats were treated with 10 microg of diethylstilbestrol (DES) on alternate days from the 2nd to the 12th postnatal day, and the testes were sequentially examined up to 105 days of age by light, electron, and confocal laser microscopy. In control rats, spermatozoa and step 19 spermatids were observed in stage VIII seminiferous tubules at 56 days of age. Spermatogenic cells in DES-treated rats differentiated normally from birth until 21 days of age, after which differentiation continued only to the pachytene-spermatocyte stage. From this age onward, spermatogenic cells older than pachytene spermatocytes were not found until 56 days of age. After this point, the cells resumed differentiation and finally became spermatozoa by 91 days of age; that is, 35 days later than control rats. Electron and confocal laser microscopy showed that in the normal rat, the formation of the ectoplasmic specialization between adjoining Sertoli cells was observed as early as 20 days of age. In contrast, the specialization was not formed until 56 days of age in DES-treated rats. Furthermore, the delay in functional maturation of this structure as the blood-testis barrier was confirmed by intercellular tracer experiments. It is clear that neonatal administration of DES delayed the establishment of the blood-testis barrier for 4 weeks. Consequently, during this period, pachytene spermatocytes were exfoliated from the seminiferous epithelium without completion of meiosis.

Computed tomography and cerebral blood flow correlations of mental changes in chronic subdural hematoma.

To elucidate the pathophysiology of mental disturbances associated with chronic subdural hematoma, we performed quantitative and three-dimensional measurements of cerebral blood flow (CBF) on xenon-enhanced computed tomographic scans in 12 patients who had chronic subdural hematomas and manifested mental disturbances. In 2 patients who had no headache or hemiparesis, minimal mass effect, and severe multiple infarctions on computed tomographic scan, mentation did not improve after surgery. The CBF reduction was severe, and it further deteriorated after surgery. On the other hand, mentation improved to a varied extent in the other 10 patients, who had headache and/or hemiparesis and minimal, moderate, or severe mass effect and minimal or moderate multiple infarctions on computed tomographic scan. The CBF reduction was diffuse on both sides, but was more marked in the thalamus and putamen than it was in the cortex and subcortex. It was restored after surgery, but insufficiently. The restoration rate was statistically significant only in the thalamus, on both sides (with and without hematoma) (P less than 0.05). Dementia scores and CBF values after surgery were correlated on the side with the hematoma in the frontal cortex and thalamus (P less than 0.01) and in the hemisphere and temporoparietal cortex (P less than 0.05). There was no correlation on the side with the hematoma in the occipital cortex, putamen, and frontal and temporoparieto-occipital subcortices or on the side without the hematoma. The thalamus undergoes displacement and distortion by the hematoma, which in turn leads to changes in consciousness. Postoperative residual mental deficits consist primarily of dementia related to preexisting multiple infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological changes in human cerebral arteries after percutaneous transluminal angioplasty for vasospasm caused by subarachnoid hemorrhage.

Light and electron microscopy were used to study morphological changes in cerebral arteries after percutaneous transluminal angioplasty (PTA) for vasospasm in two patients with aneurysmal subarachnoid hemorrhage. One patient died of gastric bleeding 5 days after PTA. Postmortem examination of the inflated middle cerebral arteries revealed heterogeneously extended walls and dilated lumina. Throughout the vessel walls, the extracellular matrix, which was composed of nonmuscle components such as increased collagen, was stretched in conjunction with the medial muscle component. Also, torn and thinned areas of the wall and intramural hemorrhages were caused by overinflation. The second patient died of massive cerebral infarction caused by diffuse vasospasm 5 days after PTA. Prominent stretching of the walls at the atheromatous plaque margin in the dilated vessel was found in addition to the morphological changes observed in the first patient. These observations suggest that characteristic pathological alterations might be present in the vessel wall at the site of angioplasty. The major mechanism of the long-lasting effects of PTA seems to be the stretching and disruption of both the degenerative muscle and the proliferative nonmuscle components, mainly in the media of the vasospastic vessels.