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Biomedical subjects

F Sakai

Publications and source records attributed to F Sakai.

At least 163 records · Page 9Linked to original sources
PubMed1983

Urinary sex-dependent low molecular weight proteins as a sign of narcotic dependence in male rats.

The relationship between urinary excretion of sex-dependent low molecular weight proteins (LMWP) in male rats and narcotic dependence has been investigated in this study. Chronic administration of codeine (0.5 mg/g food) caused a significant decrease in urinary excretion of LMWP from the third day, without any change in urinary high molecular weight proteins. The decrease recovered to the control level after the withdrawal of codeine. Withdrawal symptoms including loss of body weight and diarrhea were observed following codeine withdrawal. In animals chronically treated with pethidine (1.0 mg/g food), however, neither changes in urinary LMWP excretion nor withdrawal symptoms were observed. These present findings suggest that the decrease in urinary excretion of sex-dependent LMWP is related to narcotic dependence in male rats, since we previously reported the decrease in urinary excreted LMWP in morphine-dependent rats.

Albuminuria↗
PubMed1982

Distribution of gamma-glutamyl transpeptidase and glutaminase isoenzymes in the rabbit single nephron.

"Phosphate-independent maleate-stimulated glutaminase" was investigated as a function of gamma-glutamyl transpeptidase (gamma-GTP). The activity of gamma-GTP in brush border membranes was found to be four times higher than that in the microsomal fraction of the renal cortex. This gamma-GTP activity was exclusively located in the proximal tubule of isolated single nephrons. Specific activity of gamma-GTP was 105 U/g protein (19.8 microU/mm length) in the first 2 mm portion of the proximal tubule and 1352 U/g protein (209 microU/mm) in the last 2 mm portion of the proximal straight tubule. Activity of phosphate independent glutaminase (PIG) was distributed in the same patterns as those of gamma-GTP, not only in the subcellular fractions, but also in the isolated nephron segments. On the other hand, phosphate dependent glutaminase (PDG) was distributed highly in the papillary mitochondrial fraction and in the distal tubule. Observations on the effect of pH on the enzyme activities of gamma-GTP and PDG showed that these enzyme activities were decreased significantly when the pH of the assay mixture was lowered. In the case of PIG, however, the effect of pH was just reversed. From these findings, it may be possible to interpret that gamma-GTP may play an important role in ammonia production in the brush border membrane of the proximal tubule as a function of glutaminase.

Animals↗
PubMed1982

Cyclic AMP-dependent protein kinase activity and endogenous protein phosphorylation in isolated cortical segments of rabbit nephron.

Cyclic AMP-dependent protein kinase activity and endogenous protein phosphorylating activity are reported for 6 cortical segments of the rabbit nephron which were microdissected and collected according to their morphology. The 6 cortical nephron segments, namely the glomerulus (Glm), proximal convoluted tubule (PCT), proximal straight tubule (PST), cortical ascending limb of Henle's loop (CAL), distal convoluted tubule (DCT), and cortical collecting tubule (CCT), showed protein kinase activities which were increased 1.8-4.9 fold by 10(-6) M cyclic AMP in the presence of histone IIA, histone f2b or histone f3 as a protein substrate. However, all these segments showed little or no cyclic AMP dependent increase of activity with either protamine or alpha-casein as a protein substrate. Cyclic AMP increased the endogenous protein phosphorylation of Glm (10(-6) M cyclic AMP), of CAL (10(-7) and 10(-8) M cyclic AMP), of DCT (10(-6) M cyclic AMP) and of CCT (10(-8), 10(-7) and 10(-6) M cyclic AMP). In contrast, PCT showed decreased endogenous protein phosphorylation in the presence of 10(-7), 10(-5) and 10(-4) M cyclic AMP.

Animals↗
PubMed1981

Localization of kallikrein-like activity along a single nephron in rabbits.

In order to investigate the presence of renal kallikrein, the localization of kallikrein-like proteolytic activity along a single nephron was determined in rabbits. Single nephrons were dissected into 8 segments under a microscope. Activity was fluorometrically measured with two different substrates (benzoyl-L-arginine ethyl ester: BAEE and prolyl-phenylalanyl-arginine-methylcoumarin amide: MCA). Proteolytic activity could be detected in the early (S1), the middle (S2), and the terminal (S3) portions of the proximal tubule and in the granular portion of the distal tubule (DCTg). With MCA, the specific activity in S1, S2, S3 and DCTg was 0.77 +/- 0.08, 0.28 +/- 0.10, 0.13 +/- 0.05, and 0.27 +/- 0.05 pmoles/microgram/min, respectively. The activity in DCTg was inhibited by aprotinin but that in the proximal tubules was not inhibited. No activity was found in the glomerulus, the thick ascending limb of Henle's loop, the bright portion of the distal tubule, and the light portion of the cortical collecting tubule. The inhibition of the activity by aprotinin in DCTg suggests that intrarenal kallikrein could be localized only in DCTg.

Animals↗
PubMed1981

BBM-928, a new antitumor antibiotic complex. III. Structure determination of BBM-928 A, B and C.

Structures of antitumor antibiotics BBM-928 A, B and C have been determined. They are cyclic decadepsipeptides containing 3-hydroxy-6-methoxyquinaldic acid as a chromophore. Two amino acids, not found in nature, L-beta-hydroxyl-N-methylvaline and trans-(3S,4S)-4-hydroxy-2,3,4,5-tetrahydropyridazine-3-carboxylic acid, were identified as structural constituents of the antibiotic. In gross structure, BBM-928 resembles the echinomycin group of antibiotics which are cyclic octadepsipeptides having a quinoxaline chromophore, but BBM-928 differs from the latter group by virtue of the lack of a sulfur-containing cross linkage.

Antibiotics, Antineoplastic↗
PubMed1980

Noninvasive regional cerebral blood flow measurements in dementia.

Regional cerebral blood flow measured in patients with dementias (N = 60) using xenon Xe 133 inhalation was compared with measurements in health volunteers (N = 70). Volunteers were age-matched (N = 15); another group was younger. In normal aging, there is progressive, diffuse reduction of weight and flow of gray matter (F1) but not of white matter. Therefore, age-matched control subjects are necessary in studies of dementia. In Alzheimer's disease (AD), F1 shows bilateral and symmetrical reduction. The F1 reduction correlated with atrophy estimated by computerized tomography, and duration and severity of dementia. In multi-infarct dementia (MID), bilateral hemispheric F1 was patchily reduced. Cerebral vasodilator response to 5 percent carbon dioxide inhalation was reduced in patients with MID but was normal in patients with AD. Patients with Wernicke-Korsakoff's dementia showed normal values. Patients with dementia due to multiple sclerosis showed significant F1 reduction compared with normal subjects. Standard behavioral activation in all patients with moderate to severe dementia failed to produce normal F1 increases.

Adult↗
PubMed1980

Aging and cerebral vasodilator responses to hypercarbia: responses in normal aging and in persons with risk factors for stroke.

Cerebral vasodilator responses to hypercarbia were tested during inhalation of 5% CO2 in air by normal volunteers with and without risk factors for cerebral atherosclerosis. The results were compared with those of patients with hemispheric infarction or ischemia or vertebrobasilar arterial insufficiency (VBI). Regional cerebral blood flow was measured by the 133Xe inhalation method before and during hypercarbia. Responsiveness to CO2 was expressed as the percentage increase of gray matter flow per mm Hg of end-tidal CO2 tension. Cerebral vasodilator responsiveness is mildly impaired by the atherosclerosis of normal aging, is moderately impaired in normal subjects with risk factors for cerebral atherosclerosis, and is greatly impaired in patients with symptomatic hemispheric ischemia and VBI. Testing regional cerebral blood flow with CO2 appears to be a useful, harmless screening test for cerebral atherosclerosis.

Adult↗
PubMed1980

Normal human sleep: regional cerebral hemodynamics.

Measurements of regional cerebral blood flow (rCBF) by the xenon 133 inhalation method along with polygraph recordings were made serially during relaxed wakefulness and different stages of nocturnal sleep in 18 right-handed normal volunteers. During stage I-II sleep the fast flow (Fg) values declined significantly, more in the brainstem-cerebellar (BSC) regions than in hemispheric regions. During stage III-IV sleep, Fg further declined diffusely in both hemispheric (-28%) and BSC (-29%) regions. During awakening from stage IV sleep to alpha-frequency wakefulness, BSC flow values increased more than hemispheric flow values. During REM sleep, regional Fg values increased diffusely in both hemispheric (+41%) and BSC (+47%) regions compared with wakefulness. There was a significant inverse correlation between the increase in end-tidal partial pressure for carbon dioxide and the reduction in bihemispheric Fg during sleep. Cerebral vasomotor responsiveness to carbon dioxide is decreased during both REM and non-REM sleep.

Adult↗