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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 271 records · Page 15Linked to original sources
PubMed1997

Benzodiazepine receptors in chronic cerebrovascular disease: comparison with blood flow and metabolism.

UNLABELLED: The brain benzodiazepine (BZD) receptor distribution in patients with chronic cerebrovascular disease was assessed with 123I-iomazenil (IMZ) SPECT, and the findings were compared with the data for the cerebral blood flow (CBF) and cerebral metabolism. METHODS: We examined nine patients with chronic cerebrovascular diseases, six patients with cerebral infarction and three with moyamoya disease. Iodine-123-IMZ SPECT images were obtained for 15 min, 3 hr after the administration of 167 or 222 MBq 123I-IMZ. In seven patients, the CBF and oxygen metabolism were measured by the 50 steady-state method. In two patients, the CBF and glucose metabolism were measured by 99mTc-HMPAO SPECT and 18F-fluoro-2-deoxy-D-glucose-PET, respectively. The brain was initially classified into 18 regions, and abnormalities in the BZD receptor distribution, CBF and cerebral metabolism were visually evaluated. The count ratio of lesion-to-contralateral normal region (L-to-C ratio) was then used for comparison. RESULTS: In the core of the infarct, the 123I-IMZ uptake decreased (L-to-C ratios of the blood flow 0.42 +/- 0.26; metabolism 0.45 +/- 0.24; and 123I-IMZ uptake 0.46 +/- 0.14). In the peri-infarct region, the 123I-IMZ uptake slightly decreased (L-to-C ratios of 0.81, 0.82 and 0.89, respectively). In the region of misery perfusion, the 123I-IMZ uptake was preserved (L-to-C ratios of 0.73, 1.07 and 1.02, respectively). In the remote deafferentiated areas in the ipsilateral cerebrum, the 123I-IMZ uptake was preserved (L-to-C ratios of 0.76 +/- 0.10, 0.75 +/- 0.04 and 0.98 +/- 0.05, respectively). In the remote areas in the contralateral cerebellum, the 123I-IMZ uptake was preserved (L-to-C ratios of 0.84 +/- 0.08, 0.85 +/- 0.04 and 0.94 +/- 0.05, respectively). CONCLUSION: The BZD receptor distribution, as measured by 123I-IMZ SPECT, is not considered to reflect neuronal function, but it may reflect neuronal cell viability. Iodine-123-IMZ SPECT may, therefore, hold promise as a potential probe for neuronal damage.

Brain↗
PubMed1997

[An surgical case of right pulmonary coccidioidomycosis--with subcutaneous coccidiomycosis in the left wrist].

Coccidioides is an afferent fungus disease. In Japan, there have been only a few surgical reports on coccidioides disease. We report a 39-year-old male who was diagnosed as having coccidioides disease by biopsy of subcutaneous nodules in the left wrist. The patient also showed a tumor image (1.5 x 1.0 cm) in S4 in the right lung. He had previously lived in Fresno, California on business between 1988 and 1993. After biopsy of the subcutaneous nodules, Itraconazole (200 mg), an anti-fungal drug, was orally administered for the lesion in the right lung for about 6 months. Since the tumor image revealed no improvement through this treatment, the tumor was resected. Histopathological examination by Grocott staining demonstrated the spherical form Coccidioides, i.e., endospores. Only 5 cases of resected pulmonary coccidioidal lesions have been reported in Japan including this case. We must be careful when handling coccidioidal culture because of its strong infectiosity.

Adult↗
PubMed1997

A simple method of intraoperative limb length measurement in total hip arthroplasty.

The equalization of leg-length discrepancy during total hip arthroplasty can be achieved through the use of a simple measuring device, the Calipers Dual Pin Retractor. During total hip arthroplasty a stable reference point must be established to determine leg-length changes. The Calipers Dual Pin Retractor was developed to establish a fixed point on the pelvis, which would remain constant throughout the procedure, from which the distance to the trochanteric area could be measured prior to the dislocation of the hip. This measurement is then used to aid in the proper placement of the femoral components.

Anthropometry↗
PubMed1997

Two optimal prefilter cutoff frequencies needed for SPECT images of myocardial perfusion in a one-day protocol.

OBJECTIVE: The purpose of this study was to determine if cutoff frequencies of two-dimensional Butterworth filters need to be changed, depending upon the amount of radiopharmaceutical administered in one-day protocols for reconstructing SPECT images of myocardial perfusion. METHODS: A scintilation camera and a phantom were used with 2.2 MBq and 10.6 MBq 99mTc. These activities corresponded to the approximate amounts used in our one-day myocardial perfusion imaging protocol. The projection data were collected in 30 positions spread over 180 degrees. Thirty- and 150-sec acquisitions per position were performed to obtain the study and the high-quality reference images. Thirteen cutoff frequencies of the filter were used to reconstruct the SPECT images. Optimal cutoff frequencies were determined by visual assessment and by calculating the normalized mean square error (n.m.s.e). These results were then compared. The same protocol was used to image three volunteers with no heart disease and the images were evaluated visually. RESULTS: In the phantom study, the optimal cutoff frequencies were 0.225 cycles/pixel for 2.2 MBq, and 0.275 cycles/pixel and 0.25 cycles/pixel for 10.6 MBq by visual inspection, and were 0.225 cycles/pixel and 0.275 cycles/pixel by calculating the n.m.s.e., respectively. In the patient study, the lower cutoff frequency of 0.20 cycles/pixel was optimal for the exercise study (low dose), while the higher cutoff frequencies of 0.275 cycles/pixel was optimal for the resting study (high dose). CONCLUSION: The optimal cutoff frequencies differed for the two activity levels. Cutoff frequencies should be changed according to the amounts of radiopharmaceuticals used for the first and the second examinations in one-day protocols.

Heart↗
PubMed1997

A biomechanical study of fast throwing movements of the shoulder in baseball pitching.

OBJECTIVE: To define the biomechanic function of the shoulder in fast throwing movements in baseball pitching. METHODS: Using NAC high-speed video and PIAS LA-555 computer system, overhand pitching movements carried out by 12 healthy Japanese professional baseball pitchers were analyzed in three dimensions. The pitching motion was displayed as stick to sick figures dynamically. RESULTS: Pitching motion was a combination of translational and rotational movements. Acceleration and deceleration, being two typical motion patterns, worked sequentially through the anatomic link system from the pivot leg to the pitching hand. During the acceleration phase, the shoulder joint acted as a junction point and a fulcrum, supporting the rotational acceleration motion, shoulder forward flexion and elbow extension. According to the changing glenohumeral angles of the pitching shoulder, shearing force turned into tension force which worked on the anterior shoulder structures and then shifted to the posterior part of the joint. CONCLUSIONS: In fast throwing motion, the shoulder functions as an important fulcrum to support the pitching arm during the acceleration phase. Avoiding excessive stress and shearing force on the joint components and enhancing coordination of muscle action are important to a successful throwing motion and the prevention of shoulder injury.

Athletic Injuries↗
PubMed1996

Essential requirement of an invariant V alpha 14 T cell antigen receptor expression in the development of natural killer T cells.

NK1.1+ T [natural killer (NK) T] cells express an invariant T cell antigen receptor alpha chain (TCR alpha) encoded by V alpha 14 and J alpha 281 segments in association with a limited number of V betas, predominantly V beta 8.2. Expression of the invariant V alpha 14/J alpha 281, but not V alpha 1, TCR in transgenic mice lacking endogenous TCR alpha expression blocks the development of conventional T alpha beta cells and leads to the preferential development of V alpha 14 NK T cells, suggesting a prerequisite role of invariant V alpha 14 TCR in NK T cell development. In V beta 8.2 but not B beta 3 transgenic mice, two NK T cells with different CD3 epsilon expressions, CD3 epsilon(dim) and CD3 epsilon(high), can be identified. CD3 epsilon(high) NK T cells express surface V alpha 14/V beta 8 TCR, indicating a mature cell type, whereas CD3 epsilon(dim) NK T cells express V beta 8 without V alpha 14 TCR and no significant CD3 epsilon expression (CD3 epsilon(dim)) on the cell surface. However, the latter are positive for recombination activating gene (RAG-1 and RAG-2) mRNA, which are only expressed in the precursor or immature T cell lineage, and also possess CD3 epsilon mRNA in their cytoplasm, suggesting that CD3 epsilon(dim) NK T cells are the precursor of V alpha 14 NK T cells.

Animals↗
PubMed1996

Characterization of crosslinked collagens synthesized by mature articular chondrocytes cultured in alginate beads: comparison of two distinct matrix compartments.

We have characterized immunohistochemically and biochemically the collagens accumulating in two compartments of the matrix formed by mature bovine articular chondrocytes in alginate beads. At all times of the 28-day culture period, more than 90% of the collagen molecules were recovered from the rim of cell-associated matrix (CM) which encapsulates individual chondrocytes and chondrocyte clusters. Both the total amount and concentration of collagens in this matrix compartment rose progressively with time. The ratio of collagen/proteoglycan remained relatively constant with time and was always five to seven times higher in the CM than in the interterritorial matrix compartment further removed from the cells. In the CM, collagen types II, IX and XI were present on Day 28 in relative proportions (95/l/3) similar to those in adult cartilage. A higher proportion of newly synthesized collagen type XI than types II or IX molecules did not become incorporated into the pericellular rim of matrix but accumulated in the further removed matrix. Although collagen type I was synthesized in small amounts by flattened cells at the surface of the beads, it did not become incorporated as heterotrimers or homotrimers in the matrix. Mature pyridinium crosslinks, principally pyridinoline, were detected as early as Day 7 of culture but became much more abundant between Days 15 and 28, especially in the CM which contained at all times more than 90% of the crosslinks formed. The codistribution of collagen types II, IX and XI and mature collagen-specific crosslinks support the contention that mature chondrocytes cultured in alginate matrix surround themselves with a protective shell whose composition is very similar to that which encapsulated the cells in vivo.

Alginates↗
PubMed1996

Characterization of the core promoter of the Na+/K(+)-ATPase alpha 1 subunit gene. Elements required for transcription by RNA polymerase II and RNA polymerase III in vitro.

We have analyzed the core promoter element of the Na+/K(+)-ATPase alpha 1 subunit gene by means of an in vitro transcription system composed of a HeLa nuclear extract. 5'-deletion and 3'-deletion analyses revealed that this gene is specifically transcribed by RNA polymerase II in a manner that is dependent on the upstream regulatory region of the gene (-102 to -61), and that the 3' boundary of the minimal promoter element does not extend beyond +5. Analysis of linker-substitution mutations and point mutations revealed that the TATA-like sequence (-33 to -26) is required for upstream-sequence-dependent transcription whereas linker-substitution mutations and point mutations near +1 did not abolish transcription. The gene was found to be transcribed by RNA polymerase III when phosphocellulose column fractions were assayed. Deletion analysis mapped the minimal RNA-polymerase-III--specific promoter element from -49 to +17. The phosphocellulose 0.3-M-KCl fraction is absolutely required for transcription by RNA polymerase III, while the 0.85-M-KCl fraction represses aberrant transcription from incorrect initiation sites. Analysis of linker-substitution mutations indicated that the TATA-like sequence is required for RNA-polymerase-III--specific transcription. Although point mutations in the 5' half of the TATA-like sequence did not affect transcription, those in the 3' half shifted the transcription initiation site 3 bp upstream. The results suggest the the Na+/K(+)-ATPase alpha 1 subunit gene promoter contains a TATA-like sequence which can direct transcription by RNA polymerase III in vitro. The mechanism of alternative regulation of RNA polymerase II and RNA polymerase III is discussed.

Base Sequence↗
PubMed1996

Changes in glucose transporter 2 and carbohydrate-metabolizing enzymes in the liver during cold preservation and warm ischemia.

In order to examine glucose metabolism in liver grafts during cold preservation (24 and 48 hr), warm ischemia (60 and 120 min), a combination of the two and reperfusion, the amount of protein and mRNA of glucose transporter 2 and the activities of enzymes in glycolysis (glucokinase, phosphofructokinase, pyruvatekinase), gluconeogenesis (glucose 6-phosphatase, fructose 1,6-bisphosphatase), and the pentose phosphate pathway (glucose 6-phosphate dehydrogenase) were measured. It appeared that glucose transport, the pentose phosphate pathway, and gluconeogenesis were maintained during cold preservation and warm ischemia. The activity of glucokinase significantly decreased from the control value of 1.33 +/- 0.23 IU/g protein to 0.70 +/- 0.17 (24 hr, P<0.05) and 0.57 +/- 0.12 (48 hr, P<0.01) only during cold preservation. However, the activity of phosphofructokinase significantly decreased from the control value of 4.37 +/- 0.06 IU/g protein to 2.67 +/- 0.15 (60 min, P<0.0001) and 1.53 +/- 0.06 (120 min, P<0.0001) only during warm ischemia. This indicates that glycolysis deteriorates during both cold preservation and warm ischemia and demonstrates further that the balance between glycolysis and gluconeogenesis shifts to gluconeogenesis. Even when cold preservation was combined with warm ischemia, the activity of glucokinase decreased only during cold preservation and the activity of phosphofructokinase decreased only during warm ischemia. Furthermore, these changes were time-dependent. It is suggested that they can be used as a clock to measure the durations of cold preservation and warm ischemia separately and that the magnitude of an ischemic injury to a liver and a liver graft's viability can be indirectly estimated before transplantation.

Animals↗
PubMed1996

Complete primary structure of the subunits of heterodimeric phospholipase A2 from Vipera a. zinnikeri venom.

Molecular weight determination of dimeric phospholipase A2 from Vipera aspis zinnikeri venom (PLA2-I) was performed with electrospray ionization mass spectrometry (ESI-MS). PLA2-I consists of an acidic and a basic subunit (subunit A and B), which bind noncovalently and dissociate under highly acidic conditions. The protonated molecular ions of subunit A and B were measured to be 13,655.9 and 13,842.6, respectively. The complete amino acid sequence was also determined by Edman sequencing of the S-pyridylethylated derivative and its peptides derived from enzymatic digestion. Both subunit A and B consist of 122 amino acid residues and contain 7 disulfide bonds. The theoretical molecular mass calculated from the primary structure completely agree with the ESI-MS data. THe sequential homology between subunit A and B was 63.9%; however, subunit A lacks enzymatic and biological activities that are characteristic for phospholipase A2. Although the amino acid residues essential for calcium binding (Tyr28, Gly30, Gly32, and Asp49) and catalysis (Asp92) were preserved, replacement of functionally important residue (His48) for catalysis with a Gln was found in subunit A. In addition, substitution of acidic amino acid residues for basic ones and hydrophilic residues for hydrophobic ones were observed in subunit A. Presumably, these changes in the primary structure of subunit A resulted in the loss of enzymatic activity and an increase in the binding ability with subunit B.

Amino Acid Sequence↗
PubMed1996

A comparison of latanoprost and timolol in primary open-angle glaucoma and ocular hypertension. A 12-week study.

OBJECTIVE: To evaluate the intraocular pressure (IOP)-reducing effect and the side effects of latanoprost (PhXA41), a new phenyl-substituted prostaglandin F2 alpha-isopropyl ester analogue, in patients with elevated IOP, using timolol maleate as the reference drug. METHODS: A total of 184 patients with primary open-angle glaucoma or ocular hypertension at 35 medical centers participated in this randomized double-masked study. The patients were randomized to receive either 0.005% latanoprost once daily or 0.5% timolol maleate twice daily, for a period of 12 weeks. Intraocular pressure was measured 24 hours after the administration of timolol, at 2, 4, 8, and 12 weeks of treatment. RESULTS: Latanoprost reduced IOP at the end of 12 weeks by 6.2 +/- 2.7 mm Hg (mean +/- SD) (26.8%), while timolol reduced IOP by 4.4 +/- 2.3 mm Hg (19.9%). At all visits latanoprost reduced IOP significantly more than timolol did. The main ocular side effects observed in both groups were conjunctival hyperemia and smarting. The main systemic side effect was a reduced pulse rate, which occurred in patients treated with timolol. CONCLUSIONS: The results of this study demonstrated that 0.005% latanoprost taken once daily is well tolerated and more effective in reducing IOP than 0.5% timolol taken twice daily. Thus, latanoprost may become an important choice for the medical treatment of glaucoma.

Adrenergic beta-Antagonists↗
PubMed1996

Relationships between fiber composition and NMR measurements in human skeletal muscle.

The purpose of this study was to examine the relationships between the relative contents of phosphocreatine (PCr), inorganic phosphate (Pi), beta-adenosine triphosphate (ATP), and transverse relaxation time (T2) with fiber composition, which determined histochemically in the human skeletal muscle. The vastus lateralis muscles of 28 volunteers were subjected to phosphorus nuclear magnetic resonance (31P NMR) spectroscopy, magnetic resonance imaging (MRI) and muscle biopsy. Muscle fibers were divided into type I and type II fibers using myosin ATPase stain. A wide range of fiber composition levels were observed in the subjects (27.3-74.6% type I fibers). The PCr/ATP, Pi/ATP and (PCr + Pi)/ATP ratios were positively related to the percentage of type II fibers (r = 0.695, p < 0.001, r = 0.429, p < 0.05 and r = 0.773, p < 0.001, respectively). There was no correlation between fiber composition and the PCr/Pi ratio (r 0.127, n.s.) or intracellular pH (r = 0.305, n.s.). Moreover, no correlation was found between T2 and fiber type (r = 0.144, n.s.). These results suggest that 31P NMR can detect the differences in relative content of phosphates between type I and type II fibers, thereby noninvasively evaluating fiber composition in human skeletal muscle.

Adenosine Triphosphate↗
PubMed1996

Cerebellar vascular response to acetazolamide in crossed cerebellar diaschisis: a comparison of 99mTc-HMPAO single-photon emission tomography with 15O-H2O positron emission tomography.

Various observations on the cerebellar vasoreactivity in crossed cerebellar diaschisis (CCD) have previously been reported. The purpose of this study is to clarify the difference between oxygen-15 H2O positron emission tomographic (PET) and technetium-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission tomograph (SPET) findings in CCD and to evaluate the effect of the absolute values of the cerebellar blood flow as measured by 15O-H2O PET on the 99mTc-HMPAO SPET findings. The subjects comprised 15 patients with a supratentorial infarct and CCD. The cerebellar blood flow increased by about 40% at 5 and 20 min after acetazolamide i.v. on both the CCD and the non-CCD side, as measured by 15O-H2O PET. The percentage differences in cerebellar blood flow between the CCD and the non-CCD side were -22.3%+/-5.7% in the resting state, -19. 6%+/-6.4% at 5 min after acetazolamide i.v. and 21.5%+/-6.7% at 20 min after acetazolamide i.v., as measured by 15O-H2O PET, while they were -10.6%+/-5.5% in the resting state and -5.6%+/-5.1% at 5 min after acetazolamide i.v., as measured by 99mTc-HMPAO SPET. After Lassen's linearization correction, the latter two measurements were -16.2%+/-7.7% and -9.6%+/-8.9%, respectively. The effect of acetazolamide did not differ between the CCD and the non-CCD side in 15O-H2O PET, while a greater response on the CCD side was observed in 99mTc-HMPAO SPET, even after Lassen's linearization correction. It is concluded that acetazolamide HMPAO SPET may overestimate the cerebellar vascular response on the CCD side (or underestimate it on the non-CCD side).

Acetazolamide↗
PubMed1996

The usefulness of FDG positron emission tomography for the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer: a comparative study with X-ray computed tomography.

We evaluated the usefulness of fluorine-18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) in the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer and then compared the findings with the results of X-ray CT by region based on the histological diagnoses. We examined 29 patients with non-small cell lung cancer. One hundred and thirty-two mediastinal lymph nodes were surgically removed and the histological diagnoses were confirmed. FDG PET images, including 146 mediastinal regions, were visually analysed and the mediastinal lymph nodes were scored as positive when the FDG uptake was higher than that in the other mediastinal structures. On the X-ray CT scans, any mediastinal lymph nodes with a diameter of 10 mm or larger were scored as positive. All three examinations were successfully performed on 71 regions. For FDG PET, we found a sensitivity of 76%, a specificity of 98% and an accuracy of 93%. On the other hand, for X-ray CT a sensitivity of 65%, a specificity of 87% and an accuracy of 82% were observed. A significant difference was observed in respect of both specificity and accuracy (P<0.05). Based on the above findings, FDG PET is suggested to be superior to X-ray CT when used for the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer.

Aged↗
PubMed1996

Human middle latency auditory evoked magnetic fields.

The magnetic equivalents of SN10, Po, Na, Pa, Nb and Pb (SN10m, Pom, Nam, Pam, Nbm, and Pbm) in short and middle latency auditory evoked potentials were measured with a 7-channel DC superconducting quantum interference device (SQUID). The sources of Pom, Nam, Pam, Nbm and Pbm responses were estimated to be located in the auditory cortex, while the source of SN10m was considered to be in a deeper part of the brain. In addition, the source of Pam was estimated to be in the vicinity of the moving N100m source. The source of Pbm was considered to be in a separate area, anterior to the source of Pam and N100m, which suggested that source of Pam was located in the primary auditory cortex, while the source of Pbm was located in the secondary auditory cortex. The source of N100m was considered to spread from the primary auditory cortex to the secondary auditory cortex.

Adult↗
PubMed1996

Asymptomatic colorectal cancer detected by screening.

PURPOSE: Colorectal cancer screening has become prevalent. To discuss the efficacy of screening, we studied the characteristic of asymptomatic colorectal cancer detected by screening. METHODS: This is a retrospective review of patients with colorectal cancer treated at our institution. During the past 20 years, 96 of 1,046 cases of colorectal cancer were asymptomatic and detected by screening. Sixty-one of these cases were detected in the recent five years. The initial screening procedures were fecal occult blood test in 51 cases, sigmoidoscopy or colonoscopy in 18, barium enema in 9, and other tests in 18. RESULTS: Thirteen lesions (14 percent) were smaller than 1.0 cm and 32 (33 percent) were 1-2 cm in size. There were 34 Tis, 21 T1, and 8 T2 tumors. Of the 55 Tis or T1 lesions, 14 showed nonpolypoid growth (5 flat-elevated, 7 flat-elevated with depression, 1 flat, 1 depressed), and 12 of these were detected on endoscopy. Thirty-four cases were TNM Stage 0, 25 were Stage I, 16 were Stage II, 12 were Stage III, and 9 were Stage IV. Sixty-one percent of those detected by screening were in either Stage 0 or Stage I compared with 16 percent in the symptomatic group. Cumulative five-year disease-free survival rates were 100 percent for both Stage 0 and Stage I, 94 percent for Stage II, and 52 percent for Stage III. Overall cumulative five-year survival rate was 87 percent for those detected by screening, compared with 57 percent in symptomatic patients. CONCLUSIONS: Asymptomatic cancers detected by screening were at a less advanced stage. In particular, many nonpolypoid early cancers were detected by endoscopic screening.

Aged↗
PubMed1996

Cerebral blood flow and vascular response to hypercapnia in hypertensive patients with leukoaraiosis.

Both arteriosclerosis and leukoaraiosis have a close relationship with hypertension, but the relationship between cerebral hemodynamics and leukoaraiosis in hypertensive patients has not been fully examined. To clarify this issue, we measured the regional cerebral blood flow (rCBF) and cerebrovascular response to hypercapnia in hypertensive patients with various degrees of leukoaraiosis. The subjects consisted of 7 normotensive normal controls and 17 hypertensive patients. The hypertensive patients were divided into three groups according to the severity of white matter lesions (leukoaraiosis) on MRI and the presence of dementia, namely, (1) negative or mild leukoaraiosis without dementia, (2) moderate to severe leukoaraiosis without dementia and (3) severe leukoaraiosis with dementia. Both the rCBF and the cerebrovascular response to hypercapnia were measured by the O-15 H2O bolus-injection method and positron emission tomography. The rCBF in hypertensive patients without dementia did not decrease when compared with the normotensive controls, but the rCBF in hypertensive patients with dementia markedly decreased in the cerebral cortices and white matter. On the other hand, the cerebrovascular response to hypercapnia declined with the severity of leukoaraiosis, and it decreased most severely in patients with severe leukoaraiosis and dementia. Our results indicate that the reduction in the cerebral hemodynamic reserve capacity has a close relationship with the severity of leukoaraiosis in hypertensive patients, although the rCBF is maintained in hypertensive patients without dementia, and suggest that arteriosclerotic change reduces cerebrovascular CO2 response and causes a leukoaraiosis in hypertensive patients.

Adult↗