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Biomedical subjects

A Tajima

Publications and source records attributed to A Tajima.

At least 19 recordsLinked to original sources

Simple method for isolation of primordial germ cells from chick embryos.

A simple one step centrifugation method was developed for purification of primordial germ cells (PGCs) of chick embryos. PGCs, constituting less than 0.1% of the total blood cells of stage 13-14 embryos that contained a microliter amount of blood, were concentrated at the interface of a 6.3% (w/v) and 14.4% (w/v) Ficoll bilayer by centrifugation at 800 x g for 30 min. the purity of these PGCs was 86%, which was 22 times that obtained previously.

Animals

Differences and similarities in albumin and red blood cell flows through cerebral microvessels.

The hypothesis that microvessels in brain parenchyma are continuously perfused by plasma but intermittently perfused by red blood cells (RBCs) was tested in awake Sprague-Dawley rats. The microvascular distribution volumes of radioiodinated serum albumin (RISA) and 51Cr- and 55Fe-labeled RBCs were measured for periods from 15 s to 30 min. Local cerebral blood flow (LCBF) was assessed by the iodoantipyrine technique. The RISA and RBC distribution volumes were constant in the 12 areas studied from 15 s onward. These data fit a model of continuous plasma flow with intermittent RBC flow (and thus support the hypothesis), but they are also consistent with other models, e.g., continuous flow of both plasma and RBCs through all perfused microvessels. In parallel with LCBF, microvascular blood volume varied greater than 10-fold among brain areas. Relative to arterial hematocrit, microvascular hematocrits were low, which indicates that the passage of RBCs through parenchymal microvessels is more rapid than that of RISA. This could be the result of both the Fahraeus effect and intermittent RBC flow.

Animals

Technique-dependent variations in cerebral microvessel blood volumes and hematocrits in the rat.

To quantitate small parenchymal microvessel blood volumes in the brain, the distribution spaces of radiolabeled red blood cells (RBC) and serum albumin (RISA) were assessed in rats by different methods of tissue sampling and radioassay. Three minutes after intravenous administration of 55Fe-RBCs and/or 125I-RISA, the rats were decapitated. The brain was either immediately frozen within the skull and later removed (head-frozen group) or rapidly removed from the skull and then frozen (brain-frozen group). Radioactivity was measured either by liquid scintillation counting of tissue pieces, which contained pial plus large and small parenchymal microvessels, or by quantitative autoradiography (QAR) of tissue sections, which indicated small parenchymal microvessel blood only. In 12 of 15 areas, the RISA, RBC, and blood volumes determined by liquid scintillation counting of head-frozen tissue pieces were equal to or greater than those of brain-frozen tissue; this indicated less than or equal to 25% greater blood retention in pial and parenchymal microvessels with head freezing. At the parenchymal microvessel level (QAR assay), the distribution volumes of RBCs, RISA, and blood were similar with the two freezing techniques; hence with QAR either freezing procedure can be used to assess small parenchymal microvessel blood volumes.

Animals

Cerebral glucose utilization and blood flow in adult spontaneously hypertensive rats.

Not only blood pressure but also behavioral activity, brain morphology, and cerebral ventricular size differ between young spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. This suggests that cerebral blood flow and cerebral metabolism may vary between these two rat strains. To test this hypothesis, we measured local cerebral glucose utilization in 31 brain areas of 26-30-week-old rats. Local cerebral blood flow was also assessed in these same areas. Cerebral glucose utilization was measured by the 2-deoxyglucose method; cerebral blood flow was determined by the iodoantipyrene method. In virtually all gray matter structures, the apparent rate of glucose utilization was lower in SHR than in normotensive WKY rats; the interstrain differences varied significantly among structures and were statistically significant (uncorrected t tests) in 14 of 28 gray matter areas. Local cerebral blood flow was fairly similar in the two rat strains. The coupling of blood flow to glucose utilization varied significantly among brain areas in normotensive WKY rats as well as in SHR. In a number of gray matter structures, the coupling of flow to metabolism differed between hypertensive and normotensive animals. These data suggest that for many brain areas, either glucose utilization or glucose partitioning differs between WKY rats and SHR.

Analysis of Variance

A method to obtain avian germ-line chimaeras using isolated primordial germ cells.

Primordial germ cells (PGCs), collected from the blood of 2-day-old chick embryos, were concentrated by Ficoll density centrifugation. The blood contained 0.048% PGCs and the concentrated fraction contained 3.9% PGCs in blood cells. The PGCs were picked up with a fine glass pipette, and one hundred were then injected into the terminal sinuses of 2-day-old Japanese quail embryos (24 somites); bubbles were then inserted to prevent haemorrhage. The embryos were further incubated at 38 degrees C for 24 h, and then fixed. Serial sections were stained with the periodic acid-Schiff reagent (PAS) to demonstrate chicken PGCs and with Feulgen stain to identify quail cells. On the basis of the differences in staining properties, 63.6 +/- 5.3 chick PGCs were detected in the quail embryo in the area where the gonads develop. Furthermore, 39.3 +/- 4.5 chick PGCs were incorporated into the quail germinal epithelium within 24 h of the injection. A similar percentage of the host (quail) PGCs had also migrated to the germinal epithelium at the same stage of development. This technique for obtaining germ-line chimaeras will facilitate research on avian germ-line differentiation.

Animals

Malignant fibrous histiocytoma in the skull--case report.

A 45-year-old male presented with a large calvarial mass caused by a malignant fibrous histiocytoma arising primarily from the frontal bone and extending into the intracranial space. Magnetic resonance imaging revealed a well-demarcated, mottled enhanced bulky tumor with several low-signal separations. He underwent extensive tumor and bone removal, followed by radiation therapy. Histological examination showed pleomorphic spindle cells in a storiform pattern. The tissue stained positive for alpha-1-antitrypsin and alpha-1-antichymotrypsin by immunohistochemical techniques.

Frontal Bone

[The distribution and localization of alpha 1-adrenoceptor agonist on the bladder and urethra of female rats].

The distribution of selective alpha 1-adrenoceptor agonist 1-(2',5'-dimethoxyphenyl)-2-glycinamidoethanol hydrochloride, midodrine, and its active metabolite 1-(2',5'-dimethoxyphenyl)-2-aminoethanol, DMAE, was evaluated on bladder and urethra of 8-weeks and 52-weeks old female rats. Prior to the intravenous injection of 14C-labeled midodrine and DMAE, bilateral ureters were ligated to prevent drug uptake from the urinary tract. In 8-weeks rats, 14C-midodrine activity was significantly (p less than 0.01) higher in the bladder than in the femoral muscle, which served as a control for drug distribution. Similarly, higher uptake of 14C-DMAE was observed in the bladder than in the femoral muscle (p less than 0.01) and the urethra (p less than 0.05). In 52-weeks rats, there was no significant difference of midodrine uptake among these tissues. However, significantly higher uptake of 14C-DMAE was observed in the urethra than in the femoral muscle (p less than 0.05). Compared with midodrine, the concentration of DMAE was significantly increased in the bladder of 8-weeks rat and in the urethra of 52-weeks rats (respectively, p less than 0.05). In autoradiogram, the grains corresponding to midodrine and DMAE were diffusely distributed on the smooth muscles of bladder (mainly bladder neck and trigone) and urethra. The grains were also recognized on the vessels and perivascular areas of these tissues. These findings support that midodrine and DMAE could be effective for stress incontinence, because these drugs are known to bind specifically to alpha 1-adrenoceptor.

Adrenergic alpha-Agonists

Functional variations in parenchymal microvascular systems within the brain.

Variations in microvascular system functions were observed among a number of brain areas. The rates of local blood flow varied 18-fold among areas and were extremely high in neuroendocrine structures. Marked differences in blood flow were also found within some brain structures. The volume of radiolabeled blood in perfused parenchymal microvessels ranged from 5 to 70 microliters/g and correlated closely with local cerebral blood flow. The hematocrits within parenchymal microvessels were 45-75% of the arterial hematocrit, which indicates that red cells more rapidly traverse brain microvessels than do plasma proteins. The mean transit times of blood through parenchymal microvessels were extremely short and ranged from 0.3 to 0.6 s.

Animals

The effects of chronic serum sickness on albumin distribution and glucose utilization in rat brain.

The level of cerebrospinal fluid (CSF) protein is elevated in diseases and disease models that are associated with circulating immune complexes such as serum sickness. Circulatory immune complexes are known to deposit in the basal lamina of fenestrated capillaries and may, as a result, affect both capillary bed and parenchymal function. Since the brain has both fenestrated and unfenestrated capillaries and immune complexes deposit to a varying extent in the fenestrated capillaries in chronic serum sickness, cerebral capillary permeability to protein may be altered in some brain areas and lead to the elevation of CSF proteins. In addition various other cerebrovascular and metabolic functions may also be affected by this condition. In this study either radio-iodinated serum albumin (RISA) or 2-[14C]deoxyglucose (14C-2DG) was intravenously injected into control Wistar rats and Wistar rats with chronic serum sickness; subsequently the tissue levels of radioactivity were measured by quantitative autoradiography in 4 brain areas with fenestrated capillaries and 11 brain areas with unfenestrated capillaries. The 2-min distribution of RISA, which demarcates the volume of circulating plasma in perfused microvessels and is generally proportional to local plasma flow, was the same in control and experimental rats. The passage of RISA from blood into brain over 30 min was negligible in both groups; thus cerebral capillary permeability to albumin was not detectably increased in any of these 15 brain areas by chronic serum sickness. The rate of local cerebral glucose utilization, an indicator of local metabolic and neural activity, was calculated from the 14C-2DG data and was virtually identical in control and experimental rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins

Separate mechanisms of long-term potentiation in two input systems to CA3 pyramidal neurons of rat hippocampal slices as revealed by the whole-cell patch-clamp technique.

Excitatory synaptic transmission from two input systems to hippocampal CA3 pyramidal neurons was investigated by the whole-cell patch-clamp technique for thin slice preparation, with special reference to long-term potentiation (LTP) in these systems. Excitatory postsynaptic currents (EPSCs) evoked by fimbrial stimulation consisted of two components; one was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the other was persistent at depolarized membrane potentials and blocked by D-2-amino-5-phosphonovalerate (D-AP5). The contribution of the D-AP5-sensitive component to EPSCs evoked by stimulation of mossy fibers was much less than that to fimbrial EPSCs. High-frequency stimulation of afferent fibers, under current-clamp conditions, elicited LTP. Bath application of D-AP5 blocked the induction of LTP in the fimbrial but not in the mossy fiber synapses. Induction of fimbrial LTP was completely blocked by 10 mM BAPTA applied intracellularly. In contrast, mossy fiber LTP was not blocked by 10 mM BAPTA. Furthermore, mossy fiber LTP, but not fimbrial LTP, was elicited by high-frequency stimulation under voltage-clamp (-80 mV) conditions. These results suggest that activation of NMDA receptors, increase in postsynaptic [Ca2+]i, and postsynaptic membrane depolarization are required for the induction of fimbrial but not for mossy fiber LTP.

2-Amino-5-phosphonovalerate

Sequence rearrangement in JC virus DNAs molecularly cloned from immunosuppressed renal transplant patients.

From nonimmunocompromised individuals, we have recently identified a possible archetypal JC virus DNA sequence from which various regulatory sequences of JC virus isolates derived from patients with progressive multifocal leukoencephalopathy (PML) could have evolved. In this study, we analyzed the regulatory sequences of JCV DNAs cloned from urine samples of a PML risk group (renal transplant patients on immunosuppressive therapy). A number of JC virus DNAs were molecularly cloned from virions excreted in the urine of eight patients. Furthermore, fragments containing the regulatory region were amplified by the polymerase chain reaction and subsequently molecularly cloned from cell-associated JC virus excreted in the urine of two patients. The regulatory regions in all clones were analyzed with restriction enzymes, and those in representative clones were sequenced. We found that clones with the archetypal regulatory sequence were predominant in all urine samples, but a few clones carried regulatory sequences that diverged from the archetypal sequence by deletion or duplication. The finding that sequence rearrangement in the archetypal regulatory region occurs in the course of infection in immunosuppressed hosts is consistent with the adaptation hypothesis which has been put forward to explain the divergence of the regulatory regions in PML-derived JC virus isolates.

Base Sequence

[Cyclosporine induced nephrotoxicity and juxtaglomerular apparatus in mice].

To elucidate the relationship between Cyclosporine (Cs) induced nephrotoxicity and juxtaglomerular (JG) apparatus, we carried out biochemical and morphological experiments using mice. Adult male ICR strain mice weighing about 40 g were used. The mice were divided into 2 groups: the Cs group (Cs 50 mg/kg/day was orally given for 14 consecutive days) and the control group (olive oil for 14 days). Urine was stored for 24 hours on the day 0, 7 and 14 and urine volume and concentrations of urinary creatinine (u-Cr) and urinary potassium (u-K) were measured in each group. All the mice were sacrificed and examined on the 15th day. Concentrations of serum creatinine (s-Cr), serum potassium (s-K), plasma renin activity (PRA), plasma aldosterone (Ald) were noted in each group. The kidneys were also examined histologically with light and electron microscopes. The Cs group showed significant increases of s-K, PRA and Ald and a significant decrease of creatinine clearance compared with the control group. Histologically, the Cs group demonstrated focal vacuolar changes in the proximal tubular cells and an increase in the number of granules in the JG cells. Each granule of the Cs group was larger than that of the control group. Cs certainly stimulates the renin-angiotensin-aldosterone system and causes consequently a secondary aldosteronism.

Animals

[Cyclosporine induced nephrotoxicity and renal blood flow].

To elucidate the relationship between cyclosporine (Cs) nephrotoxicity and renal blood flow (RBF), we carried our experiments using rats. Adult male Wistar strain rats each weighing about 100 g were used. Rats were divided into 2 groups; the Cs group (Cs 50 mg/kg/day was intraperitoneally given for 10 consecutive days) and the control group (normal saline solution for 10 consecutive days). The renal cortical blood flow was measured in each group by electrolytic hydrogen gas clearance method. We also carried out renal angiography with barium sulfate (BaSO4). Then we measured blood vessel area/renal sagittal section area ratio and the diameter of interlobar arteries. The Cs group showed a significant decrease of renal cortical blood flow compared with the control group. On the other hand there was no significant change in renal angiogram. In conclusion, Cs decreased renal cortical blood flow. We suppose that vascular resistance increased following afferent arteriolopathy caused by Cs administration.

Animals