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Biomedical subjects

M Mohri

Publications and source records attributed to M Mohri.

At least 127 records · Page 7Linked to original sources
PubMed1990

Characteristics of increased urine flow during a dry saturation dive at 31 ATA.

Three male divers were subjected to a 7-day dry saturation dive at 31 ATA (New Seatopia). Urine samples were collected for measurements of electrolytes and creatinine for glomerular filtration rate (GFR) 5 times daily, at 3-h intervals during daytime (0700-2200 h) and once at night (2200-0700 h). Collections were taken for 2 days before (predive 1 ATA air), 7 days during 31 ATA exposure, and during 10 days of decompression and for 2 days at postdive 1 ATA air. Blood samples were taken after overnight fasting at each of the dive periods for measurements of atrial natriuretic factor (ANF), electrolytes, and other blood constituents. Compression to 31 ATA resulted in a twofold increase in urine flow accompanied by increases in excretion of osmotic substances (+40%) and sodium (+54%), and a reduction in urine osmolality (-32%). The increase in urine volume was greater (P less than 0.05) at night than day with no change in GFR between day and night, confirming the earlier findings. However, no change in plasma ANF was observed in spite of a sustained increase in daily sodium and water excretion at high pressure. These results suggest that the hyperbaric diuresis-natriuresis may not be directly mediated by the ANF release.

Adult↗
PubMed1989

Effects of hyperbaric environment on human auditory middle latency response (MLR) and short latency somatosensory evoked potential (SSEP).

Hyperbaric chamber dives at 19 ATA with helium-oxygen were performed at the Japan Marine Science Technology Center from November 15 to December 3 in 1988 and from January 25 to February 4 in 1989. During simulated underwater experiments, auditory middle latency responses (MLRs) and short latency somatosensory evoked potentials (SSEPs) were recorded in 3 professional divers (2 divers in each dive) for assessment of brain function. During the saturation dive (180 m below sea level) component Pa on MLR was lost, while component Po remarkably increased in amplitude. These MLR changes rapidly recovered between the beginning of decompression and at about 90 m below sea level. On the other hand, N9-N20 interpeak latency on SSEP slightly or moderately increased in the both divers, but N9-N14 interpeak latency was not affected by the 19 ATA saturation dive. These results suggest that the hyperbaric environment corresponding to 180 m below sea level cause some cerebral dysfunctions, probably between the brainstem and the cortex, but these dysfunctions are only transient.

Adult↗
PubMed1989

Amelioration by beta-adrenergic blockade of regional myocardial dysfunction induced by coronary artery occlusion after, but not before collateral development in conscious dogs.

Effects of beta-adrenergic blockade on regional myocardial dysfunction induced by coronary artery occlusion were studied in chronically instrumented, conscious dogs before (n = 8) and after (n = 7) collateral development. Intravenous atenolol or propranolol produced no beneficial effects on systolic shortening in the area rendered ischemic during 2 minutes of circumflex occlusion, before collateral development. After the collateral development by repetitive 2-minute coronary occlusions, regional asynergy recovered to the preocclusive level during 2 minutes of occlusion. Both atenolol and propranolol significantly improved the peak reductions of regional shortening by 19 +/- 9% and 18 +/- 9%, respectively (p less than 0.05 versus without beta-blockade). These beneficial actions of beta-blockade were again noted during atrial tachypacing at matched heart rates of 160 +/- 11 beats/min. Thus the beneficial effects of beta-blockade on regional asynergy during coronary occlusion depend on the level of functional state of the collaterals and cannot be totally accounted for by the reduction in heart rate or by the cardioselectivity.

Animals↗
PubMed1989

Duration of ischemia is vital for collateral development: repeated brief coronary artery occlusions in conscious dogs.

The effects of two types of repeated transient coronary artery occlusions on collateral development were examined in chronically instrumented, conscious dogs. A 2-minute coronary occlusion at 32-minute intervals (group 1, n = 11) or a 15-second occlusion at 4-minute intervals (group 2, n = 7) were repeated day and night without interruption. In both groups, the total duration of coronary occlusions each day was the same (90 minutes). Before and after repetitive occlusions of either group, effects of transient 2-minute coronary occlusion on regional segment shortening in the ischemic area were examined to assess the functional state of the collateral vessels. In group 1, systolic segment shortening in the area rendered ischemic was reduced to -97.8 +/- 17.7% of the preocclusive control value during 2 minutes of coronary occlusion. After 125-478 repetitive occlusions (3-11 days), the degree of hypokinesia during the 2-minute occlusion was significantly improved to -0.6 +/- 4.6% of the preocclusive value (p less than 0.001 vs. before the repetition). In group 2, it remained unchanged even after 3,500-5,450 repetitive occlusions (11-16 days): -111.8 +/- 8.2% before and -111.4 +/- 13.8% after the repetition of 15-second occlusions (NS). The ratio of peripheral coronary arterial pressure to aortic pressure during transient-coronary occlusion, measured by selective catheterization, was significantly higher in group 1 than in group 2 (64.4 +/- 5.3% vs. 20.7 +/- 1.3%, p less than 0.001). These findings suggest that myocardial ischemia of 2 minutes but not 15 seconds is vital to provide effective stimuli for angiogenesis.

Angiography↗
PubMed1989

Isosorbide dinitrate ameliorates myocardial ischemia after development of collateral function in a canine model.

The effects of i.v. administered isosorbide dinitrate (ISDN) on the reduced level of regional myocardial function during coronary occlusion were studied in conscious dogs before and after collateral development and in the absence of persistent coronary stenosis. The animals were instrumented during sterile surgery with a miniature pressure gauge for measuring left ventricular pressure and a cannula for aortic pressure. Two pairs of piezoelectric crystals were placed in normal and ischemic areas to determine regional circumferential length. A hydraulic cuff occluder and a Doppler flow probe were placed around the left circumflex coronary artery. Collaterals were induced to develop by 2 min of coronary occlusion applied repetitively at an interval of 32 min for 2 to 9 days, until the regional dysfunction produced by coronary occlusion had disappeared. Collateral development was estimated according to percentage of systolic shortening and endsystolic length area (ESL area) during the occlusion. Before collateral development, ISDN in a dose of 100 micrograms/kg did not affect the level of regional dysfunction. The ESL area was 250 +/- 54 and 248 +/- 52 mm.sec before and after ISDN, respectively. After collateral development, the ESL area was 51 +/- 13 mm.sec and it decreased by 35% after the i.v. administration of ISDN. The improvement by ISDN of transient myocardial dysfunction was achieved even during electrical tachypacing. Accordingly, the beneficial effects of ISDN on regional wall motion rendered ischemic during transient coronary occlusion were appreciable after coronary collateral development.

Animals↗
PubMed1988

Topographic electroencephalographic studies in a hyperbaric environment--specific reference to high pressure nervous syndrome.

Hyperbaric chamber dives at various equivalent depths below sea level, i.e. 7, 14, 19 and 31 atmosphere absolute (ATA) with helium-oxygen or helium-nitrogen-oxygen have been performed at the Japan Marine Science and Technology Center. A two-dimensional (topographic) display of the scalp EEG was used during simulated underwater experiments to determine; 1) Whether there are any characteristic EEG patterns in high pressure nervous syndrome (HPNS), 2) the relationship between the EEG changes and the compression rate, and 3) the relationship between the EEG changes and the characteristic signs and symptoms of HPNS. A two-way analysis of variance and a distribution analysis technique revealed that the topographic brain patterns depended on the diving depth and indicated the most affected brain areas during compression and decompression. Significant correlations between the diving depth and the EEG potentials were observed at different brain locations. Alpha waves showed a diffuse cortical distribution. Theta wave activity was more localized in the frontal midline region. These waves developed paroxysmally in relatively brief bursts supplanting or intermixing with normal background EEG rhythms. In our subjects, frontal midline theta activity was associated mostly with some of the characteristic features of HPNS, such as a transient episode of laughter or euphoria at depths greater than 21 ATA. An intimate correlation between frontal midline theta wave and laughter was observed. Frontal midline theta waves may be related to emotional activities induced by helium under high pressure. There were significant individual variations in susceptibility and subjective signs and symptoms. The EEG is of great value in studying man's physiological reactions in an undersea environment and also very important in selecting divers who are relatively more tolerant of a severe hyperbaric environment.

Adult↗
PubMed1988

Effects of a hyperbaric environment on human brain stem function with specific reference to auditory brain stem responses.

Hyperbaric chamber dives at 31 ATA with helium-oxygen were performed at the Japan Marine Science and Technology Center in 1987. During simulated underwater experiments, auditory brain stem responses were recorded in 4 professional divers for assessment of brain stem function. All divers had no clinical symptoms at 150 m below sea level, and their ABRs also showed no significant changes. During the 150-250 m depth saturation dives, all divers complained of various symptoms such as euphoria, ataxia, joint pain, tremor and dyspnea, while, I-III and I-V interpeak latencies on their ABRs increased with a tendency of recovery. Furthermore, the changes of both interpeak latency were independent of each other. These results indicate that transient dysfunction clinically or subclinically occurred at the processes between 150-300 m below sea level. Moreover, independent changes of I-III and I-V interpeak latencies in this study may mean that the pathways reached to the generation sites of wave III and V were different.

Adult↗
PubMed1988

Microcomputer-assisted filing system of cardiac catheterization records using a relational database management system.

To efficiently store and retrieve cardiac catheterization records, we have developed a computer-assisted database, which comprises a 16-bit microcomputer with dual floppy disk drives, a 20 MB random-access memory, hard disk drive, and a line printer. All programmings were accomplished using a relational database management system (R:base 5000, Microrim, Inc.). Data inquiry procedures could be performed with direct operational commands of the system as well as with preprogrammed command files, and final results of searches were printed out with a line printer. The major advantages of the present system described in this report include: (1) the relatively easy and rapid creation of the database, (2) ease of modification of the database structures even after the system design is finished, (3) operational commands in combination with conditional operator(s) are flexible and powerful enough to allow the end user to retrieve data based on various kinds of criteria, (4) a high-level programming language provided by the R:base automates a series of database procedures with relative ease, (5) relational capabilities of the database management system can enhance the possibility of reconstruction of a new data file from a single or several preexisting data files, and (6) the system can be realized at reasonable cost.

Cardiac Catheterization↗
PubMed1988

Biphasic response of coronary arterial diameter to intracoronary ergonovine.

This report presents a case of paradoxical coronary arterial dilation induced by intracoronary ergonovine. When compared with the control angiogram, the right coronary artery obviously dilated with selective, intracoronary administration of cumulative doses of 5 micrograms and 15 micrograms ergonovine without concomitant hemodynamic changes. Additional intracoronary infusion of 35 micrograms ergonovine into the right coronary artery inversely increased vascular tone of the vessel associated with a focal hyperconstriction. Such a biphasic response of arterial diameter to intracoronary ergonovine was also observed in the left coronary artery, but the degree of dilation was much smaller.

Angina Pectoris, Variant↗
PubMed1988

The clinical features and pathogenesis of myringitis granulosa.

Myringitis granulosa is not a rare pathologic condition of the tympanic membrane. However, the condition can be misdiagnosed as chronic suppurative otitis media, since intermittent purulent discharge is the commonest symptom in both disorders. Although the clinical features of myringitis granulosa have been well described by several authors, its pathogenesis is still obscure. In this study, 40 cases of myringitis granulosa were examined in detail to clarify the clinical features and the pathogenesis present. No drum perforations, no hearing impairments and normal X-ray findings indicated that myringitis granulosa had no relation to chronic suppurative otitis media. The other areas of the affected tympanic membrane, except for the site of granulation, showed such pathologic conditions as atrophy, clouding and calcifications. In these pathologic tympanic membranes, epithelial migration was disturbed to a high degree. We suggest that the granulation process on the tympanic membrane should be divided into two stages: (1) injury reaching the lamina propria of the tympanic membrane; and (2) disturbed epithelization of the tympanic membrane. The disturbance of epithelial migration of the tympanic membrane occurs with both stages.

Diagnosis, Differential↗
PubMed1986

Reactive dilation and late-hyperemic constriction of epicardial coronary artery after short coronary occlusion.

Coronary blood flow and epicardial coronary artery diameter were simultaneously measured by an electromagnetic or Doppler flow probe and a pair of ultrasonic crystals, respectively, during reactive hyperemia in conscious dogs. Reactive dilation appeared after the full appearance of reactive hyperemia and lasted for a period of 4-20 times the duration of the coronary occlusion. beta-Receptor blockade (propranolol, 1 mg/kg iv) attenuated both the reactive hyperemia in volume by 21-22% (P less than 0.01) and dilative responses of the epicardial coronary diameter by 27-28% (P less than 0.01), despite a nonsignificant attenuation of the resting or peak hyperemic coronary blood flow. When coronary blood flow was held constant during reperfusion, by an occluder distal to the ultrasonic crystals, the reactive dilation disappeared. A peculiar reactive constriction was noted when coronary occlusion was performed proximal to the site of the ultrasonic crystals. Appearance of this constriction was at 149 and 385 s after the release of 5 and 60 s of coronary occlusion, respectively. This late reactive constriction disappeared after pretreatment with alpha- (phentolamine, 1 mg/kg iv) and/or alpha- + beta-blockade, but not with beta-blockade alone, and it was not observed when the coronary diameter was measured proximal to the occluder. Thus reactive dilation of the epicardial coronary artery derives from an increase in coronary flow and is reduced by propranolol via a reduction in the hyperemic flow, suggesting a flow-dependent change in the diameter of the epicardial coronary artery. Reactive constriction is a local phenomenon following marked reduction in the coronary diameter and is abolished by alpha-adrenergic blockade with phentolamine.

Adrenergic alpha-Antagonists↗
PubMed1985

Detection of different blood flow patterns in the true and false lumina with aortic root dissection by pulsed Doppler echocardiography.

We report a 53-year-old man with aortic dissection, in whom pulsed Doppler echocardiography showed two different flow patterns within the dilated aorta. Although two-dimensional echocardiography has been successful in making the diagnosis of aortic root dissection, several conditions producing false positives have also been noted. Simultaneous recording of pulsed Doppler echocardiography may be useful to provide additional diagnostic clues in selected cases.

Aortic Dissection↗
PubMed1985

Changes in pituitary-adrenal function under extreme cold in DHA-treated persistent estrous rats.

The plasma corticosterone levels and incorporation of 14C-l-acetate into corticosterone and cortisol were measured in dehydroepiandrosterone (DHA)-treated persistent estrous rats and control estrous cyclic rats exposed to cold (-5 degrees C) for 12 hrs. Cold exposure significantly facilitated incorporation of 14C-l-acetate into corticosterone and cortisol in both DHA-treated and control rats. However, the rates of increase of plasma corticosterone level and 14C-incorporation into corticosterone are 61% and 77% in controls, and 19% and 44% in DHA-treated rats, respectively. The activity of stress-induced pituitary-adrenal function showed masculine patterns in DHA-treated rats. The diurnal patterns of plasma corticosterone in DHA-treated rats are similar in controls. Plasma corticosterone levels in DHA-treated rats are evidently greater than those in controls. It is suggested that neonatal administration of DHA caused the changes not only in pituitary-gonadal system but also in pituitary-adrenal system.

Animals↗
PubMed1983

Changes in pituitary-adrenal function under continuous exposure to hypoxia in male rats.

The plasma corticosterone concentration and incorporation of 14C-1-acetate into adrenocortical hormones were measured in male rats exposed to hypoxia (12.5% O2 in N2 balance) for periods of 30 min--14 days. Hypoxia significantly increased the weight of the adrenal and pituitary glands in early stages of exposure. However, weight returned to the control level on the 14th day of exposure. Hypoxia consistently decreased the weight of the thymus. Hypoxia elevated the plasma corticosterone concentration in the early stages of exposure. However, the elevated corticosterone level gradually decreased by the 7th day. The corticosterone level at this stage was lower than in the control. The corticosterone concentration returned to the control level on the 14th day. Hypoxia significantly facilitated incorporation of 14C-1-acetate into corticosterone and cortisol in the adrenal homogenate. The elevated incorporation was maintained until the 7th day and gradually decreased to the control level there after. Body weight was decreased by hypoxia (12 gram in 24 hours). On the 5th day, the weight returned to the control level. Hematocrit increased gradually during 14 days of hypoxia exposure. These results suggest that pituitary-adrenal function is greatly facilitated by 1-6 hours of hypoxia exposure, and hypoxia acclimatization is accomplished humorally within 14 days of exposure in rats.

Acetates↗