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Biomedical subjects

R Sakamoto

Publications and source records attributed to R Sakamoto.

At least 37 records · Page 2Linked to original sources
PubMed1995

Oxygen transport and cardiovascular effects of resuscitation from severe hemorrhagic shock using hemoglobin solutions.

OBJECTIVE: To test the short-term efficacy of three hemoglobin solutions in restoring cardiac output, intravascular pressures, oxygen transport (DO2), and oxygen consumption (VO2) after resuscitation from severe hemorrhagic shock. DESIGN: Prospective study. SETTING: Research laboratory. SUBJECTS: Beagle dogs. INTERVENTIONS: After anesthesia and instrumentation, hemorrhagic shock was induced for 2 hrs by blood withdrawal to maintain systolic blood pressure at 50 mm Hg. Resuscitation then occurred with one of four different resuscitation fluids. One group of dogs was not resuscitated. Survival rate was monitored for 8 days. MEASUREMENTS AND MAIN RESULTS: In 33 beagle dogs, cardiovascular variables (DO2 and VO2) were compared after resuscitation with 8% stroma-free hemoglobin, 4% or 8% pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP44 and PHP88, respectively), or autologous whole blood. The dogs were anesthetized, paralyzed, mechanically ventilated (FIO2 of 0.21), and instrumented with arterial and pulmonary artery catheters. An average of 63% of estimated blood volume was removed to maintain systolic blood pressure at 50 mm Hg for 2 hrs. The dogs then were either not resuscitated (n = 4) or resuscitated with 8% stroma-free hemoglobin (n = 7), PHP44 (n = 6), PHP88 (n = 8), or whole blood (n = 8), with a volume equivalent to the withdrawn blood. Cardiovascular variables, DO2, VO2, oxygen extraction ratios, and blood concentrations of lactic acid and catecholamines were determined before, and for < or = 6 hrs after, resuscitation from hemorrhagic shock. Blood smears were microscopically examined. In addition, the survival rate was monitored for 8 days after resuscitation. By 2 hrs of hemorrhagic shock, there was a large decrease in DO2 (p < .05) and an increase in oxygen extraction ratio from 0.27 to 0.70 (p < .05). There was a 3.5-fold increase in lactate concentrations and a 25-fold increase in catecholamine concentrations as compared with preshock values. All dogs not resuscitated died within 1.75 hrs after 2 hrs of shock. After resuscitation with whole blood, all cardiovascular and oxygen transport variables returned to approximately prehemorrhage values and remained so throughout the measurement period. After resuscitation with any hemoglobin solution, DO2 returned transiently to control values. However, recovery of DO2 was short-lived in all hemoglobin solution groups, and, by 4 hrs postresuscitation in all groups, DO2 was less than the DO2 of the dogs receiving whole blood (p < .05). These changes were associated with decreases in total hemoglobin concentrations compared with the values immediately before resuscitation (p < .05). In addition, with resuscitation using the PHP solutions, blood smears demonstrated aggregation of red blood cells and platelets. On day 8 after hemorrhagic shock, the survival rate was 100% for whole blood and PHP44, 86% for 8% stroma-free hemoglobin, and 33% for PHP88. CONCLUSIONS: Resuscitation from severe hemorrhagic shock with 8% stroma-free hemoglobin, PHP44, or PHP88 is equally effective in restoring cardiac index and vascular pressures as using whole blood. However, resuscitation with the three hemoglobin solutions only transiently restored DO2 after hemorrhagic shock. The subsequent reduction of DO2 compared with the DO2 value using whole blood was due mostly to hemodilution. With the two PHP solutions, formation of red blood cell aggregates probably resulted in sequestration of red cell mass and additional loss of oxygen carrying capacity.

Animals↗
PubMed1995

Radiofrequency catheter ablation for atrioventricular node reentry tachycardia with multiple slow atrioventricular node pathways.

Catheter ablation was attempted in 2 patients with atrioventricular node reentry tachycardia which showed fast, intermediate and slow anterograde atrioventricular node pathways. Radiofrequency currents were applied within a restricted area of the tricuspid annulus between the His bundle and the ostium of the coronary sinus where presumed slow pathway potentials were identified. Elimination of both the intermediate and the slow pathways, with preservation of anterograde and retrograde fast pathway conduction, was achieved in both patients.

Aged↗
PubMed1995

[A case of advanced gastric remnant carcinoma with Virchow's metastasis treated with neoadjuvant chemotherapy (low dose CDDP + 5-FU) followed by surgical resection].

The patient was a 64-year-old woman. At hospitalization she had gastric remnant carcinoma with Virchow's and paraaortic lymph node metastases, extensive local infiltration and obstructive jaundice. The lesions were considered nonresectable, and the patient was placed on neoadjuvant chemotherapy consisting of low-dose CDDP and 5-FU, which resulted in the disappearance of Virchow's and paraaortic lymph node metastases. She was considered to have a partial response (PR) and underwent lower esophageal resection, total remnant gastrectomy and splenectomy. Eight months after surgery, however, she died of disseminated carcinomatosis of bone marrow. Since this therapy was associated with only slightly adverse events (< or = Grade 1), this treatment modality appears to be safe. However, further studies will be necessary to identify what type of recurrence is responsive to this therapy and to evaluate its effect on patient survival.

Adenocarcinoma↗
PubMed1994

[Syphilitic uveitis].

Three cases of syphilitic uveitis were described in which penicillin therapy combined with oral steroid regimen afforded rash disappearance of retinal edema in all cases. However, remarkable recuperation of vision was obtained in 2 cases.

Adrenal Cortex Hormones↗
PubMed1993

Magnetic resonance imaging study on the results of surgery for cervical compression myelopathy.

The morphologic changes and signal intensity of the spinal cord on preoperative magnetic resonance images were correlated with postoperative outcomes in 74 patients undergoing decompressive cervical surgery for compressive myelopathy. The transverse area of the spinal cord on T1-weighted images at the level of maximum compression was closely correlated with the severity of myelopathy, duration of disease, and recovery rate as determined by the Japanese Orthopaedic Association score. In patients with ossification of the posterior longitudinal ligament or cervical spondylotic myelopathy, the increased intramedullary T2-weighted magnetic resonance imaging signal at the site of maximal cord compression and duration of disease significantly influenced the rate of recovery. A multiple regression equation was then developed with these three variables to predict surgical outcomes.

Cervical Vertebrae↗
PubMed1993

Mechanism of pain in osteoid osteomas: an immunohistochemical study.

Osteoid osteoma is a benign bone tumour characterized by pain which is relieved by non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin. To clarify the mechanism of the pain, five osteoid osteomas were studied immunohistochemically using polyclonal antibodies against prostaglandin E2 (PGE2), S-100 protein and protein gene product 9.5 (PGP 9.5). In all five cases, the pain had been relieved by NSAIDs. Nerve fibres positive for S-100 protein and PGP 9.5 were observed in the fibrous zone, especially close to the blood vessels, around the nidus in all the lesions and also within the nidus in three lesions. PGE2 immunoreactivity was variably positive in the nidus of three lesions. In one case a large number of actively proliferating osteoblasts reacted with this antibody. The other cases showed unevenly distributed PGE2 positivity which tended to be prominent in the plump osteoblasts. As control material we examined fibrous dysplasia (3 cases), osteosarcomas (3) and giant-cell tumours of bone (3). The plump osteoblastic tumour cells of three osteosarcomas and the bone-forming cells in two cases of fibrous dysplasia gave a positive reaction for PGE2. No S-100 or PGP 9.5 immunoreactive nerve fibres were seen in these lesions. It is concluded that the presence of nerve fibres alone might play a more important role in mediation of pain in osteoid osteomas than some effects of osteoblast-produced PGE2 on the nerves and proliferated blood vessels.

Adolescent↗
PubMed1993

Relationship between atrial conduction defects and fractionated atrial endocardial electrograms in patients with sick sinus syndrome.

The relationship between abnormal atrial electrograms (AAE) recorded during sinus rhythm by endocardial catheter mapping of the right atrium and the atrial conduction defects of sinus impulses or single atrial extrastimuli was investigated in 44 patients with sick sinus syndrome. The patients were divided into two groups on the basis of the presence (n = 29) or absence (n = 15) of AAE recorded during sinus rhythm. The P wave duration in the AAE (+) Group patients was 137 +/- 14 msec, and 125 +/- 15 msec in the AAE (-) Group; P < 0.02. The intraatrial conduction time of sinus impulses in the AAE (+) Group was 54 +/- 12 msec, and 39 +/- 9 msec in the AAE (-) Group; P < 0.001. The interatrial conduction time in the AAE (+) Group was 101 +/- 14 msec, and 78 +/- 16 msec in the AAE (-) Group; P < 0.001. In the AAE (+) Group, 11 (38%) patients had a sinus node recovery time > 4 seconds, whereas in the AAE (-) Group there was only one (6%) patient; P < 0.03. AAE showed a specificity of 93% and a positive predictive accuracy of 91% in predicting inducibility of atrial fibrillation. The sensitivity was 35% and the negative predictive accuracy was 42%. Sustained atrial fibrillation was induced in ten (35%) patients of the AAE (+) Group, and in one (7%) patient of the AAE (-) Group; P < 0.05. These data suggest that in patients with sick sinus syndrome who possess abnormal endocardial electrograms in sinus rhythm within the right atrium have: (1) a significantly longer P wave duration; (2) a significantly longer intraatrial and interatrial conduction time of sinus impulses; and (3) a significantly greater sinus node dysfunction and higher incidence of induction of sustained atrial fibrillation. It is concluded that there are significantly greater atrial conduction defects in patients with sick sinus syndrome who possess AAE within the right atrium during sinus rhythm.

Adult↗
PubMed1993

[Hemodynamic changes in patients with myocardial infarction while walking up and down stairs].

Hemodynamic changes while walking up and down stairs were studied in 53 myocardial infarction (MI) patients in the chronic phase and 31 adults of normal health. Electrocardiograms were recorded by a holter monitor and analyzed for arrhythmias and ST segment changes. Heart rate, systolic and dyastolic pressure, and pressure-rate product (PRP) were also measured by auto sphygmomanometer. These were measured at one minute intervals during the following period: resting in bed for 3 minutes in a supine position; walking to a stairway (1 minute); walking up and down 2 flights of stairs taking 30 seconds for each flight (total of 2 minutes) and returning to their bed (1 minute). All subjects then rested until they reached their starting PRP level. After walking up and down the stairs, the PRP increased significantly over that measured while the subjects were in a supine position for both the MI patients and those of normal health. However, the rate of increase for the MI patients was lower than that of the normal adults. Also, for MI patients older than 60, increases of the PRP were lower than the increases of the younger patients. This phenomenon may be due to low cardiac function, low cardiac reserve, vascular sclerosis, and the hemodynamical instability of the weak vasomoter reflex. In addition, the average recovery time after walking up and down the stairs was 1.9 minutes for MI patients, compared to 1.2 minutes for normal adults. 17% of the patients spent more than 3 minutes recovering, while the recovery times for all normal adults were within 2 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The phenol red thread tear test: a cross-cultural study.

PURPOSE: To examine the results of the phenol red thread tear test in a cross-cultural comparison. METHODS: Two groups of 500 controlled normal subjects who do not wear contact lenses from the United States and Japan were investigated. RESULTS: The mean wet length of the thread for the United States was 23.9 mm (SD 9.5 mm). The mean for Japan was 18.8 mm (SD 8.6 mm). There was a significant difference between the two countries (P < 0.05). Males subjects had significantly longer wet lengths than females for both countries (P < 0.05). There was a moderate correlation between right and left eye results for both countries. CONCLUSIONS: The phenol red thread tear test was found to be easy to administer. Results were in line with current knowledge and theories of the lacrimal system. Results also indicated that this test may disclose subtle differences not previously found with other tear tests.

Adolescent↗
PubMed1991

Comparative study between magnetic resonance imaging and histopathologic findings in ossification or calcification of ligaments.

Magnetic resonance imaging findings were compared with histopathologic specimens of ossified or calcified ligaments, including the surrounding tissue, to evaluate the usefulness of magnetic resonance imaging as a means to predict the progression of ossification. In addition, factors influencing signal intensity were evaluated by histochemical and immunohistochemical analyses. The area of low signal intensity corresponded to the hyperplastic ligament around the ossification, and to the transitional area between the ligament and the ossification. A mineralization front and chondrocyte proliferation with strong metachromasia were recognized in these areas. The presence of a low-intensity signal area suggested the progression of ossification. The isointensity signal corresponded to proliferation of small vessels in the hyperplastic ligament, presumably representing the initiation of ossification. Histochemically, the metachromasia was intense at the transitional area between the ligament and the ossification, and the main constituent in these areas was chondroitin sulfate. Immunohistochemically, S-100 protein, transforming growth factor-beta 1, and Type II collagen showed an intense immunoreactivity in the chondrocytes, indicating increased production of the extracellular matrix. We postulate that the activation of chondrocytes and the alteration of the extracellular matrix may have affected the signal intensity.

Aged↗
PubMed1990

[Paradoxical response of blood pressure to salt loading in renovascular hypertension].

We studied the effect of high salt intake on blood pressure in two cases with renovascular hypertension. They had hypertension with hyperreninemia and marked difference in plasma renin activity between both renal veins. Blood pressure significantly decreased after single oral administration of captopril. Renal arteriogram revealed significant stenosis in the main artery to the left (case 1) and right (case 2) kidney. Blood pressure response was evaluated after seven (case 1) and five (case 2) days of low salt and seven days (both cases) of high salt intake. Mean blood pressure in two patients was significantly decreased (case 1; 118 +/- 5.5 to 108 +/- 6.1 mmHg and case 2; 150 +/- 3.8 to 138 +/- 3.1 mmHg). Plasma renin activity was also decreased (case 1; 6.25 to 0.77 ng/ml/hr and case 2; 22.8 to 6.3 ng/ml/hr). In case 2, blood pressure elevated markedly during low salt intake, compared with blood pressure level during normal salt intake. The results suggest that excessive salt intake in patients with unilateral renovascular hypertension produces blood pressure reduction because of suppression of renin-angiotensin system. We concluded that in patients with unilateral renovascular hypertension dietary sodium depletion may be harmful, whereas salt supplement may have a beneficial effect.

Adult↗