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Biomedical subjects

N Aikawa

Publications and source records attributed to N Aikawa.

At least 91 records · Page 5Linked to original sources
PubMed1991

Subepicardial microischemia formation induced by epicardial application of endothelin-1.

The effects of endothelin-1 (ET-1), applied topically on the epicardium, on the coronary microcirculation of the beating canine heart were investigated in situ. ET-1 (1, 10, 100, and 1,000 pmol) induced a dose-dependent elevation of the ST segment in the epicardial ECG (n = 5). After application of ET-1 (100 pmol), the beating hearts were rapidly cross-sectioned and freeze-clamped in 120 ms using a specially developed device (n = 6). By NADH fluorescence photography of the cross-sectioned frozen sample, an increased fluorescent area in the subepicardium was clearly observable. The fluorescent dye injected from the left atrium was negative in the NADH fluorescent area. It can be concluded that ET-1, when administered extravascularly, induces severe vasoconstriction and myocardial ischemia in the microcirculation of the beating canine heart.

Administration, Topical↗
PubMed1990

Atrial natriuretic polypeptide after burn injury: blood levels and physiological role in rats.

To define the relationship between atrial natriuretic polypeptide and the physiological changes of water and electrolytes after burns, the changes in plasma hormonal levels, including atrial natriuretic polypeptide, and urinary water and sodium excretions were examined in burned rats. Further, to elucidate the physiological significance of atrial natriuretic polypeptide after burns, the effects of a specific antiserum against atrial natriuretic polypeptide were determined in burned rats. Plasma atrial natriuretic polypeptide levels in rats following 30 per cent BSA full skin thickness burns were elevated for sustained periods (432.3 +/- 156.5 pg/ml, P less than 0.01 on day 1 postburn, 244.5 +/- 73.7 pg/ml, P less than 0.05 on day 3 postburn). Urine volume and sodium excretion decreased significantly during the first 72 h after burns. On day 3 postburn, urine volume and sodium excretion began to increase significantly. Specific rabbit antiserum against atrial natriuretic polypeptide was injected into the burned rats during this diuretic phase. Significant inhibition of diuresis and natriuresis was observed after the injection of antiserum (27.5 +/- 2.4 per cen decrease in urine volume, 57.1 +/- 10.4 per cent decrease in sodium excretion). These results suggest that atrial natriuretic polypeptide plays a physiological role in the regulation of urinary water and sodium excretion after burns.

Aldosterone↗
PubMed1990

Regulation of renal function in thermal injury.

Hypovolemia, low cardiac output, and systemic vasoconstriction are major etiologic factors in acute renal failure occurring in the early postburn period, and elevated levels of stress-related hormones (catecholamines, angiotensin, aldosterone, and vasopressin) are implicated in the mechanism. By counteracting the effects of the hormones, atrial natriuretic polypeptide (ANP) regulates the renal response to burns. ANP was elevated after burns, protecting the kidneys by increasing renal blood flow and urine output. In pulmonary acid injury, increased ANP levels were associated with natriuresis which was reduced by administration of anti-ANP serum. Exogenous ANP given to dogs under constant norepinephrine infusion resulted in improvement of hemodynamic and renal parameters. To prevent tubular damage due to hemoglobinuria, a haptoglobin preparation is administered to patients with extensive third-degree burns. With sufficient fluid replacement, these new treatments will reduce the incidence of acute renal failure in the early postburn period.

Acute Kidney Injury↗
PubMed1990

Release of ANP and its physiological role in pulmonary injury due to HCl.

The effect of pulmonary injury induced by aspiration of HCl on plasma atrial natriuretic polypeptide (ANP) level was examined in rats given a constant infusion of water and electrolytes. In addition, using specific antiserum against ANP, we investigated the physiological role of ANP in rats after HCl aspiration. Rats were housed individually in metabolic cages and were given a constant infusion of sodium solution via catheters chronically inserted into the jugular vein. Plasma ANP levels were elevated at 3 and 24 h after tracheal injection of 0.2 ml of 0.1 N HCl via the cricothyroid membrane. Urine volume and urinary sodium excretion increased during the first 24 h after acid aspiration. However, this increase was reduced by the injection of anti-ANP serum. Furthermore, the injection of anti-ANP serum resulted in a significant (P less than 0.05) increase in wet lung weight from a value of 0.74 +/- 0.06 (HCl aspiration with normal rabbit serum injection) to 0.83 +/- 0.07% of body weight. These results indicate that ANP plays a physiological role in the regulation of urinary water and sodium excretion after pulmonary acid injury and suggest that ANP elevated in plasma after pulmonary injury may prevent pulmonary edema with its diuretic action and/or some direct action on water movement in the lung.

Animals↗
PubMed1989

Postoperative metabolic alkalosis following general surgery: its incidence and possible etiology.

A prospective clinical study was performed on 293 patients, in order to elucidate the abnormalities in acid-base balance following general surgery. Six arterial blood gas and pH determinations were taken from each patient before surgery and on postoperative days zero, one, three, five and seven. A total of 1699 determinations were obtained. Although the majority of patients (87.5 per cent) had a normal acid-base balance before surgery, a postoperative metabolic alkalosis was seen in 50.5 per cent of the patients. However, there was an extremely low incidence of other postoperative acid-base abnormalities, apart from a transient increase in metabolic acidosis on the operative day. A significantly high mortality rate (32.3 per cent) was observed in 31 patients who had continuous metabolic alkalosis during the postoperative period. An excessive bicarbonate load resulting from the administration of fresh frozen plasma following surgery was strongly suggested as one of the major causes of postoperative metabolic alkalosis. Further investigation is required to elucidate the mechanism of the generation of metabolic alkalosis induced by the postoperative bicarbonate load in surgical patients.

Acid-Base Equilibrium↗
PubMed1988

[Antibiotic susceptibility of bacteria isolated from surgical infection (second report)].

Isolated bacteria from infections in general surgery in 1984 and 1985 have been investigated to find bacterial composition and their susceptibilities to antibiotics in a joint research in which 6 university hospitals in Japan participated. A summary of findings from the investigation is as follows. 1. One hundred and seventy-two (1984) and 211 (1985) cases were included in the study. Cases in which bacteria were detected were 147 and 174 in the respective years. The detection rate was higher than 80% in either year. 2. Total numbers of strains isolated in 1984 and 1985 were 267 and 293, respectively; major sources of these strains were intraperitoneal infection exudates in either year. 3. The most frequent isolate from primary infection cases in both years was Escherichia coli (15-21%), followed by Bacteroides spp. and Staphylococcus spp., in that order. The most frequently isolated from postoperative infection cases were Enterococcus spp. (16-22%), followed by Pseudomonas spp. The diversity of isolated species, as well as the similarity of incidences of different species were noted in cases of postoperative infections. It is suspected that a certain species, even if its pathogenicity is essentially low, may become to be a causative organism once its number increases due to its survival through a perioperative prophylactic use of antibiotics, and also due to the decreased host resistance to infections caused by underlying diseases or surgical stress. 4. Staphylococcus spp. was the most frequent isolate from postoperative infections occurring after clean operations, while Enterococcus spp. and Pseudomonas aeruginosa were major isolates from infections after clean-contaminated operations. Isolates from infections occurring after contaminated operations included Enterococcus spp. greater than E. coli greater than Klebsiella pneumoniae, P. aeruginosa, Bacteroides spp. (1985). 5. In cases without the presence of clinical factors cause by depressed host defense, E. coli and Bacteroides spp. were major isolates, while in cases with the factors, a wide variety of bacterial population tended to be found. 6. Before an administration of antibiotics in primary infections, E. coli, Staphylococcus spp. Bacteroides spp. and Klebsiella spp. were most commonly isolated, while after a chemotherapy, Enterococcus spp. were the most frequent isolates, followed by P. aeruginosa during 1985. These findings reflected the antibacterial spectrum of cephems usually used in surgical field.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Bacterial Agents↗
PubMed1987

Clinical analysis of multiple organ failure in burned patients.

Severely burned patients often show various degrees of organ failures, and when several vital organs are involved mortality becomes extremely high. A study was undertaken to elucidate the aetiology and clinical significance of multiple organ failure (MOF) in burned patients. One hundred and fifty-eight burned patients were analysed for organ failures in five vital organs or systems, the heart, lung, liver, kidney and blood clotting system. There were 91 organ failures observed in 34 patients, of which 26 had MOF. The most frequently affected organ was the lung, followed by the heart, kidney, liver and the blood clotting system. The mortality rate was 76.9 per cent in MOF and 1.5 per cent in non-MOF patients. Septicaemia was closely associated with the development of MOF. Also, inhalation injury and 'shock' were contributing factors to the morbidity. Five extensively burned patients had an early development of MOF without infectious foci and this type of early MOF was attributed to endotoxaemia possibly originating from the patient's own intestinal flora.

Adolescent↗
PubMed1986

[Antibiotic susceptibility of bacteria isolated from surgical infections (first report)].

In vitro activities of several antimicrobial agents against bacterial pathogens isolated from patients with primary and postoperative infections were investigated in 1982 and 1983. Antimicrobial agents examined were as follows: sulbenicillin (SBPC), piperacillin (PIPC), cephalothin (CET), cefazolin (CEZ), cefmetazole (CMZ), cefotiam (CTM), cefoperazone (CPZ), cefotaxime (CTX), ceftizoxime (CZX), cefmenoxime (CMX), latamoxef (LMOX), lincomycin (LCM), gentamicin (GM) and amikacin (AMK). Specimens for bacterial isolation included plus, fluid drawn by centesis, or bile. Blood samples of septicemia were excluded. The antimicrobial activities of these drugs were determined by the agar plate dilution method of the Japanese Society of Chemotherapy. There were 123 strains obtained in the 1982 survey and 252 strains in the 1983 survey. Little or no differences were seen in frequencies of isolation between the isolates of principal species in 1982 and those in 1983. Isolation frequencies of pathogens in primary infections were, in an order of decreasing frequency, E. coli (25.6%), anaerobes (21.1%), Streptococcus sp. (14.3%), Staphylococcus sp. (11.3%); in postoperative infections, Streptococcus sp. was most frequent (28.6%), followed by Pseudomonas sp. (17.6%), anaerobes (12.6%), E. coli (10.9%), Staphylococcus (10.1%). Against S. aureus, CEZ, CTM, LCM and GM had similar degree of activity with CET being somewhat more active. CMX was the most active drug among the third generation cephems tested against S. aureus. No strain was CTM, CEZ, and LCM-resistant at the same time. Over 90% of E. coli, were sensitive to CTX, CZX and CMX, inhibited by 0.10 microgram/ml, while E. coli were slightly less susceptible to CPZ and LMOX. Penicillins were not very active against K. pneumoniae, and only 60% of K. pneumoniae were inhibited by PIPC at concentrations of 12.5 micrograms/ml. Third generation cephems, CTX, CMX and CZX, proved highly active against K. pneumoniae; over 90% of K. pneumoniae was inhibited by CTX, CMX and CZX at a concentration of 0.10 microgram/ml. About 60% of P. aeruginosa was inhibited by 3.13 micrograms/ml of PIPC and GM but was resistant to SBPC. This survey should be very useful for the selection of an appropriate drug for prophylaxis if the frequencies of incidences of pathogens in postoperative infections are taken into account in selecting the most active antibiotic agent(s) against the most frequent genus, genera and species of pathogens.

Cephalosporins↗
PubMed1984

[The third generation cephems for surgical infections].

The third generation cephems, Cefotaxime, Ceftizoxime, Cefmenoxime and Latamoxef, have been developed to aim opportunistic Gram negative pathogens and applied for surgical infections since 1980. Although they have excellent antibacterial activities in vitro against Enterobacter spp., indole positive Proteus spp., Pseudomonas spp. and Bacteroides spp., they show lower activities against Gram positive bacteria. Their pharmacokinetic characteristics are longer serum half-life, lower urinary excretion and higher biliary transmission without any metabolic inactivation in human body. Clinical trials of the third generation cephems to surgical infections in Japan revealed the average efficacy rate of 84% which might be better than that of the second generation cephems. It may be a discrepancy between their antibacterial spectrum and clinical results that responses in cases caused by Gram negatives did not exceed those by Gram positives. Clinical application of the third generation cephems should be limited to the surgical infections caused by Gram negatives in immunocompromised host to avoid the emergence of resistant strains.

Cefmenoxime↗
PubMed1982

Individualized fluid resuscitation based on haemodynamic monitoring in the management of extensive burns.

An evaluation has been made on the effectiveness and feasibility of the individualized fluid replacement programme based on intensive haemodynamic monitoring using a Swan-Ganz catheter. Twenty-one extensively burned patients with an average burn of 60.8 per cent BSA were resuscitated with lactated Ringer's and colloid solutions. The rate of fluid administration was adjusted to maintain the optimal ranges of the various haemodynamic parameters including cardiac index and left ventricular stroke work index. Two patients failed to respond to fluid resuscitation possibly due to inadequate emergency procedures given before arrival at our institute. The remaining patients survived the shock phase, with the amount of fluid given to the 18 adult patients being (3.38 /+- 1.02 ml/kg) x (percentage burn) for the first 24 hours. A negative correlation existed between the amounts of lactated Ringer's solution and colloid solution used for the fluid resuscitation. Dopamine was effective in 4 out of 5 patients who showed depressed myocardial function. The individualized fluid programme was shown to be effective and reliable for the management of critically burned patients.

Adolescent↗