Biomedical subjects

K Iwanaga

Publications and source records attributed to K Iwanaga.

At least 55 records · Page 3Linked to original sources

PubMed1996

A newly discovered age-related synaptic change in the human locus ceruleus: morphometric and ultrastructural studies.

We have recently found that in the human locus ceruleus (LC) some pigmented neurons contain granules in their cytoplasm that are immunoreactive (IR) for 38-kDa synaptic vesicle-specific protein (SVP). These represent synaptic terminals enveloped in the somatic cytoplasm. In the present study we analyzed LC pigmented neurons morphometrically in 48 autopsied individuals, whose ages at death ranged from 5 to 94 years, and also examined LC pigmented neurons ultrastructurally in 4 of these individuals. The number and incidence of LC pigmented neurons containing SVP-IR intracytoplasmic granules became significantly higher with age. The mean somatic area of the neurons was significantly higher than that of neurons without SVP-IR intracytoplasmic granules. Ultrastructurally, the synaptic terminals, which contained many round or flattened clear vesicles and sometimes dense-cored vesicles, were found to be enveloped by the somatic cytoplasm of some pigmented neurons and occasionally formed synaptic contacts with the cytoplasm. These enveloped synaptic terminals showed no apparent degenerative features. Our results strongly suggest that the enveloping of synaptic terminals by the somatic cytoplasm of human LC pigmented neurons is a phenomenon associated with the aging brain, and that this phenomenon may be related to intrinsic adaptive mechanisms of the LC pigmented neurons to certain environmental changes associated with aging.

Adolescent↗

PubMed1996

Is the intracellular pH threshold an anaerobic threshold from the view point of intracellular events?: a brief review.

Intracellular biochemical changes could be monitored noninvasivery and continuously by using nuclear magnetic resonance (NMR). In about the last decade, intracellular behavior of phosphorus compounds and pH during muscle contraction in man have been studied by 31P nuclear magnetic resonance spectroscopy (31P-MRS). During incremental load, lactic acidosis was followed by a decline in intracellular pH. 31P-MRS studies has been definitely proved that this change in intracellular pH shows the threshold behavior. Some reports discussed the intracellular pH threshold (pHT) as an anaerobic threshold (AT) from the view point of intracellular events. However, our studies revealed that pHT did not reflect the onset of lactate production. In this article, studies of intracellular pH of working muscle were reviewed in relation to an anaerobic threshold.

Anaerobiosis↗

PubMed1996

Effects of cooling portions of the head on human thermoregulatory response.

Seven healthy young male students participated in this study. Each subject sat on a chair in an anteroom at 25 degrees C for 30 min and then entered a climatic chamber, controlled at 40 degrees C and R.H. 50%, and sat on a chair for 90 min. Cooling of frontal portion including the region around the eyes (FC), occipital portion (OC), and temporal portion (TC) began after 50 min of entering. An experiment without head cooling (NC) was also made for the control measurement. Thermal comfort and thermal sensation were improved by head cooling, but response was the same regardless of portion cooled. Although rectal temperature, mean skin temperature and heart rate showed no significant effect due to head cooling, forearm skin blood flow (FBF), sweat rate (SR), and body weight loss (delta Wt) had a tendency to be depressed. FBF in FC and TC decreased during head cooling, but that in OC and NC did not change significantly, while SR in FC was depressed. delta Wt showed total sweating to decrease by FC and TC, and FC to have greater inhibitory effect on sweating than OC. Thermal strain was evaluated by the modified Craig Index (I(s)). I(s) in FC decreased significantly more than in NC. Cooling of other portions of the head had no significant effect on I(s). Cooling of the frontal portion of the head may thus be concluded to have the most effect on thermoregulatory response in a hot environment.

Acclimatization↗

PubMed1996

[A case of sleep apnea syndrome due to a nasopharyngeal tumor].

Obstructive Sleep Apnea Syndrome (OSAS) is children is commonly caused by upper airway obstruction, such as that caused by adeno-tonsillar hypertrophy. We report a rare case of SAS due to a nasopharyngeal tumor. The patient was a 10-year-old boy who complained of snoring and sleep apnea. The tumor was found in the nasopharynx and mesopharyngeal space. We diagnosed this case as OSAS by overnight sleep study (Apnea Hypopnea Index: AHI = 19.67). The tumor was removed under general anesthesia. Histopathology revealed features of nasopharyngeal angiofibroma. After removal of the tumor, his symptoms resolved completely. A follow-up overnight sleep study confirmed resolution of OSAS. At the last follow up, conducted 17 months after the operation there were no signs of tumor recurrence.

Angiofibroma↗

PubMed1996

[A case report of late-onset Huntington disease without family history and caudate atrophy who has diagnosed clinicopathologically and genetically].

We report a 66-year-old male with typical symptoms of Huntington's disease (HD), but without family history or atrophy of caudate nucleus on brain CT. The diagnosis of HD was confirmed in this apparently sporadic case by neuropathological findings as loss of small-sized neuron with gliosis in the striatum, and molecular testing of CAG repeat of the gene for HD using post mortem tissue. The DNA analysis showed that he had a mildly expanded allele with 45 repeat units, in the size range seen in HD chromosomes. The result suggests that there are some correlations between the repeat length and the clinicopathological findings such as late onset, lack of family history and insusceptible caudate atrophy.

Age of Onset↗

PubMed1996

Effect of surgery on obstructive sleep apnea.

The statistical analysis of data obtained by monitoring pre- and post-operative conditions of patients treated for sleep apnea syndrome is reported. In the past 3 years, surgery was performed on 149 patients (55 children and 94 adults), who complained of snoring and symptoms related to the sleep apnea syndrome at Fujita Health University, The Second Hospital. Treatment for children was adeno-tonsillectomy. Treatment for adults was uvulo-palato-pharyngoplasty (UPPP), midline laser glossectomy (MLG) and/or nasal surgery. Apnea hypopnea index was defined as frequency of apnea hypopnea per hour. Pathological apnea (sleep apnea syndrome) was defined as apnea hypopnea (AHI) 10 in adults and AHI 5 in children. Marked improvement was defined as 75% reduction in AHI or a postoperative AHI below 10 in adults and 5 in children. Improvement was defined as 50-74% reduction of AHI. Slight improvement was defined as 25-49% reduction of AHI. No improvement was defined as less than 25% reduction of AHI. Of these 55 children, the AHI of 35 of them was above 5. Thirty cases (86%) showed marked improvement after treatment; 3 cases (8%) showed improvement; 1 case (3%) slight improvement and 1 case (3%) no improvement. Of these 94 adults, 40 cases (48%) showed marked improvement after treatment; 12 cases (14%) showed improvement; 14 cases (17%) slight improvement and 18 cases (21%) no improvement at all.

Adenoidectomy↗

PubMed1996

Diagnosis by dynamic MRI in sleep disordered breathing.

According to the obstructive site, different types of obstructive type sleep disordered breathing are classified as the soft palate type, palatine tonsil type, soft palate and depressed lingual root type, depression of the lingual root type, and epiglottis type. In this study, we conducted dynamic MRI examinations of the oral and pharyngeal and lingual root sites in patients with obstructive sleep disordered breathing, and studied MRI's usefulness as a diagnostic tool in the examination of such obstructive sites. In this paper, we present mainly the adult cases of patients with obstructive sleep disordered breathing which appeared to be caused by an enlarged palatine tonsil.

Humans↗

PubMed1995

Variability of brain lesions in rats administered methylmercury at various postnatal development phases.

The effect of methylmercury chloride (MMC) on the developing rat nervous system was studied by light microscopy. Rats on postnatal day 2 (P2), P15 and P60 were administered 10 mg/kg/day MMC orally for 10 days. In newborn (after P2) rats, there was no abnormal activity or body weight loss. Young (after P15) rats showed weight loss on the 9th day after starting MMC, and subsequently unsteadiness, gait disturbance and paroxysmal convulsions appeared. In adult rats, weight loss began on the 6th day after starting MMC, and the hind-limb crossing phenomenon was induced on the 13th day. Histopathologically, minimal damage was found in the hippocampus and brainstem in newborn rats. In young rats, widespread neuronal degeneration was observed in the cerebral neocortex, CA3 and CA4 regions of the hippocampus, neostriatum, red nucleus, and various brainstem nuclei. In adult rats, neuronal damage was most extensive in the cerebellum and spinal dorsal nerve roots. These findings indicate that neuronal vulnerability to MMC exposure differs depending on the postnatal developmental stage and the brain region in the rat.

Age Factors↗

PubMed1995

Synaptic terminals wrapped in the somatic cytoplasm of pigmented neurons in the human locus ceruleus.

We examined the locus ceruleus (LC) of 59 autopsied individuals whose ages at death ranged from 5 to 108 years. Immunocytochemistry with synaptic vesicle-specific 38-kDa protein (SVP) revealed that clusters of SVP-like immunoreactive coarse granules were present in the somatic cytoplasm of some pigmented neurons in all individuals examined. These SVP-like immunoreactive granules were confirmed electron microscopically to be contained in synaptic terminals which were wrapped in the somatic cytoplasm of pigmented LC neurons.

Adolescent↗

PubMed1995

Dysembryoplastic neuroepithelial tumor: report of a case without typical glioneuronal elements.

We studied a temporal lobe lesion found in a 44-year-old woman with a 25-year history of intractable complex partial seizures. Histologically, the lesion contained several nodular areas differing in cellular composition within the disarranged uncal cortex; in each area, neuronal and small round cells, mature ganglion cells and fibrillary astrocytic cells predominated. Ultrastructurally, the small round cells demonstrated neuronal, astrocytic or oligodendrocytic features. The astrocytic cell processes were occasionally covered by basal laminae. The mature ganglion cells had well-developed rough endoplasmic reticulum, many mitochondria and lipofuscin granules in their cytoplasm. No dense-cored vesicles were evident. We diagnosed this temporal lobe lesion as a dysembryoplastic neuroepithelial tumor (DNT), although no areas of typical glioneuronal elements with mucinous matrix were evident. This case suggests that a glioneuronal element is not always a constant feature of DNT, and that although mature ganglion cell nodules may be present, they may differ from those of gangliocytomas and gangliogliomas in lacking intracytoplasmic dense-cored vesicles. The presence of occasional astrocytic cell processes covered by basal laminae strongly suggests that some of the constituent astrocytic cells were of subpial astrocytic origin.

Adult↗

PubMed1995

Effects of fructose ingestion on carbohydrate and lipid metabolism during prolonged exercise in distance runners.

The effects of ingestion of fructose (F), as well as of arginine (A) and citric acid (C) on both carbohydrate metabolism and lipid metabolism during prolonged exercise in seven distance runners on treadmill running were investigated by comparing it with those of glucose + arginine + citric acid (GAC) and placebo. With the values of the plasma glucose, though FAC as well as placebo contrastively indicated almost a flat distribution, GAC increased from 30 min rest before the exercise (i.e., the time for 500 ml intake of GAC) to the beginning of the exercise. The plasma glucose for GAC showed significantly higher values (138 +/- 22 mg/dl) than that for FAC or placebo, whose values were 102 +/- 18 mg/dl and 93 +/- 8 mg/dl, respectively. The plasma glucose for GAC was likely to decrease gradually as the exercise progressed more. At the end of exercise, however, the plasma glucose for FAC indicated significantly higher values (100 +/- 12 mg/dl) than that for GAC, whose values were 89 +/- 12 mg/dl. Though the serum free fatty acid showed upward tendencies of values in all cases of FAC, placebo, and GAC as the exercise progressed, no significant difference of the values in those cases was observed (the following values were drawn at the end of the exercise; FAC:655 +/- 185 microEq/l, placebo:603 +/- 289 microEq/l, GAC:485 +/- 140 microEq/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Circulatory regulation during supine and sitting intermittent isometric handgrip in a hot environment.

We studied the circulatory regulation during intermittent isometric handgrip (IIHG, six seconds contraction + six seconds relaxation) in supine and sitting postures in a hot environment (40 degrees C, RH: 50%). Eight healthy male subjects performed thrice 5-minute period IIHG at three different work loads (10%, 20% and 30% MVC). The IIHG was performed with the right hand in the two postures. Heart rate (HR), cardiac output (CO), mean arterial blood pressure (MBP), forearm blood flow (FBF), skin blood flow (SBF), foot swelling (FSW) and tympanic temperature (Tty) were measured during IIHG, resting and recovery periods. During IIHG in a hot environment, HR, MBP, FSW and Tty showed higher values in the sitting than in the supine posture. FBF during relaxation showed higher values at high work load than at low work load in the two postures. FBF showed higher values in the sitting than in the supine posture, except during relaxation at 30% MVC. It was concluded that the decrements of blood volume of splanchnic organs might be greater in the sitting than in the supine posture due to sympathetic vasoconstrictor activity, and were responsible for the redistribution of blood flow. Posture had an effect on FBF because of hydrostatic pressure.

Adult↗

PubMed1995

Changes in body shape of young individuals from the aspect of adult physique model by factor analysis.

The purpose of this study was to clarify characteristics of age-related changes in body shape in adolescence, in 11- to 19-year-old boys and girls, by using previously reported physique models of adult men and women as the scale. The scale consisted of four factors obtained by factor analysis using 30 items as variables, such as the values measured for the physique, skinfold thickness and body composition. The four factors were Factor 1: body fat, Factor 2: mass, Factor 3: leg length to height ratio, and Factor 4: length, and were interpreted in the men and women in a similar manner. The subjects were 307 boys and 368 girls; all were healthy. Thirty items were measured and included the values measured for the physique, skinfold thickness and body composition, as in the men and women. Factor scores in the subjects were standardized by mean and standard deviation for each item in the adult subjects, and calculated for individuals by using the coefficient of factor score in the adult subjects. The body shapes of the boys and girls were investigated from the factor score by age calculated for each factor. The following results were obtained: 1. Factor 1 tended to gradually decrease and reached the adult level at 15 years of age in the boys.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Metastatic leiomyosarcoma of the skull--case report.

A 65-year-old female presented with a rare intestinal leiomyosarcoma metastasis to the skull manifesting as a mass beneath the scalp. She was free of neurological and physical symptoms on admission. The tumor was totally removed with normal surrounding bone and dura. The histological diagnosis was leiomyosarcoma. Ultrastructural and immunohistochemical studies demonstrated the smooth muscle origin of the tumor. Such patients in good physical condition should be immediately treated surgically to achieve the best chance of survival.

Aged↗

PubMed1993

Method for detection of intracellular pH threshold; comparison between subjective observation and regression analysis.

The aim of this study is to examine the objectivity and reproducibility of intracellular pH threshold (pHT) detected by eye (E), and by regression analysis on linear (L), semilog (SL) and log-log (LL) models. Threshold for inorganic phosphate-to-phosphocreatine ratio (PT) was also examined by three regression analysis. Fifteen males volunteered as subjects. They performed wrist flexion in a ramp protocol of 0.14W/min till exhaustion. Throughout the exercise, 31P-MRS was obtained continuously from wrist flexors. Intracellular pH and phosphate compound in the muscle tissue were monitored as minute-by-minute data. In E, three observers determined pHT subjectively as a work rate just before pH decrement. In three regression analysis, pHT was detected as an intersection of a pair of linear regression lines which was selected statistically or subjectively. pHT detected by four methods showed significant reproducibility between each other, although PT did not. These results provide one of the evidences of threshold behavior of change in pH, and a question of existence of PT in contrast to pHT.

Exercise↗

PubMed1993

Influence of ramp slope on intracellular pH threshold during progressive exercise.

The purpose of this study was to examine the effect of ramp slope during progressive exercise test on the intracellular pH threshold (pHT) of working muscle. To attain the purpose, we measured intracellular pH of wrist flexor by 31P-MRS during four kinds of ramp wrist flexion. Five Japanese males participated as subjects. They performed wrist flexion in a bore of MRS system, with ramp increments of 0.14, 0.20, 0.26 and 0.31 W/min till exhaustion. Intracellular pH of wrist flexor muscle was estimated from a chemical shift between inorganic phosphate (Pi) and phosphocreatine (PCr) on a 31P-MR spectra. Pi-to-PCr ratio (Pi/PCr) as an index of oxidative phosphorylation potential was also calculated. pH and Pi/PCr were obtained as minute-by-minute data throughout the exercise. pHT was determined as a work rate (W) just before that at which the intracellular acidosis (acidemia) occurred. Although work endurance was shortened significantly, achieved maximal work rate (WRmax) was increased with an increase in ramp slope. pHT both in the unit of W and %WRmax was not affected significantly by the ramp slope. On the other hand, Pi/PCr at pHT decreased with an increase in ramp slope, significantly. These results suggested that intracellular homeostasis with reference to acid-base equilibrium was not dependent on oxidative phosphorylation status, but a work output of the muscle.

Exercise↗

PubMed1993

Effect of active recovery on intracellular pH following muscle contraction, a 31P-MRS study.

The effect of active recovery after intense muscular exercise was examined by 31P-MRS. Seven healthy males participated in this study, and their right wrist flexor muscles were examined. Each subject flexed the right wrist at 60% of the maximum voluntary contraction (MVC) until the intracellular pH in the wrist flexor muscle decreased to approximately 6.4. This was followed either by active recovery (AR) which consisted of 5, 10, 20, 30 or 40% MVC exercise, and by passive recovery (PR) during a 10-min-recovery period. The intracellular pH (pHi) recovered faster during AR at each condition than during PR. Besides, from the 2nd to the 5th min of the recovery period, the pHi was significantly higher during AR than during PR. The quadratic regression curve of pHi recovery during the 10-min-recovery-period against the % MVC was obtained. The optimal contraction intensity determined from this curve was 8.7% MVC for a 10-min-recovery-period. The optimal levels were determined for another recovery duration within 10 min, and the level decreased with the prolonged recovery duration. These data suggest that mild exercise is an effective maneuver to promote the recovery from intracellular metabolic acidosis, and that the intensity of the recovery exercise should be determined according to the cooling down duration or the resting interval before the subsequent exercise performance.

Adult↗

PubMed1993

Effect of restricted blood flow on intracellular pH threshold of working muscle.

Threshold of decline in intracellular pH of muscle (pHT) during incremental wrist flexion was studied by 31P-MRS, under two levels of occlusions in which the cuff of the upper arm was inflated to systolic (ES) and diastolic blood pressure (ED), and no occlusion (E). To observe the effect of occlusion per se, intracellular pH at rest under the same two levels of occlusion was measured. Additionally, NIRS was applied to monitor the oxygenation and blood volume of the tissue during the same experimental protocol as the 31P-MRS study. Ten healthy Japanese males participated as subjects in the 31P-MRS study, and three of them in the NIRS study. They performed wrist flexion in incremental loads of 0.14 W/min ramp until voluntary exhaustion. 31P-MRS and NIRS were obtained from wrist flexor muscles. Change in intracellular pH (pH) during wrist flexion showed a threshold behavior even in ischemic conditions, although pH did not decrease at rest under the same two levels of occlusion. This finding indicated that decrease in pH under occlusion is also resulted from exercise induced lactic acidosis. Obtained pHT in ES was smaller than in ED and E significantly, and there was no significant difference between pHT in ED and that in E. From the results of NIRS study, it was confirmed that only venous outflow but not arterial inflow was restricted under an occlusion at a pressure of diastolic blood pressure, but both under an occlusion at a pressure of systolic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗