Biomedical subjects

T Komatsu

Publications and source records attributed to T Komatsu.

At least 55 records · Page 3Linked to original sources

PubMed2001

Effects of posterior cruciate ligament resection on the tibiofemoral joint gap.

The effect of posterior cruciate ligament resection on the tibiofemoral joint gap was analyzed in 30 patients with varus osteoarthritis of thee knee who underwent total knee replacement. The medial soft tissue was released and the bone cut was made without preserving the bone segment of the tibia to which the posterior cruciate ligament was attached. Then the medial and lateral joint gaps in full extension and 90 degrees flexion were measured before and after the posterior cruciate ligament was resected using a tensioning device. After the resection, the flexion gap significantly increased in the medial and the lateral sides (4.8 +/- 0.4 and 4.5 +/- 0.4 mm, respectively, mean +/- standard error) compared with those seen in the extension gap (0.9 +/- 0.2 and 0.8 +/- 0.2 mm). There was no significant difference between the changes in the medial and lateral gaps. The mean value of the flexion gap was 2 mm smaller than the extension gap before the resection and 1.7 mm larger after the sacrifice. Overall, posterior cruciate ligament resection resulted in an increase in the flexion gap and made space for approximately 3-mm thicker polyethylene. The flexion gap can be controlled selectively with posterior cruciate ligament release.

Aged↗

PubMed2001

Hydrogenobacter subterraneus sp. nov., an extremely thermophilic, heterotrophic bacterium unable to grow on hydrogen gas, from deep subsurface geothermal water.

A novel extreme thermophile was isolated from a water sample derived from a deep subsurface geothermal water pool at a depth of 1500 m in the Hacchoubaru geothermal plant in Oita Prefecture, Japan. The cells were found to be straight rods, each being motile by means of a polar flagellum. Growth was observed at temperatures between 60 and 85 degrees C (optimum 78 degrees C; 120 min doubling time) and between pH 5.5 and pH 9.0 (optimum 7.5). The isolate was a strictly aerobic heterotroph capable of utilizing a number of substrates such as yeast extract, peptone, tryptone, various carbohydrates, sugars, amino acids and organic acids. Elemental sulfur, thiosulfate, sulfide or cysteine-hydrochloride was required as an electron donor for growth. Hydrogen gas did not support growth. The G+C content of the genomic DNA was 44.7 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA-DNA hybridization analysis indicated that the isolate was closely related to members of the hydrogen-oxidizing, autotrophic and thermophilic genera Hydrogenobacter and Calderobacterium. However this isolate was differentiated from the previously described species of these genera on the basis of the physiological and molecular properties of the new isolate. The name Hydrogenobacter subterraneus sp. nov. is proposed; the type strain is HGP1T (= JCM 10560T = IFO 16485T).

Bacteria↗

PubMed2001

Paramyxovirus accessory proteins as interferon antagonists.

A new role of the Paramyxovirus accessory proteins has been uncovered. The P gene of the subfamily Paramyxovirinae encodes accessory proteins including the V and/or C protein by means of pseudotemplated nucleotide addition (RNA editing) or by overlapping open reading frame. The Respirovirus (Sendai virus and human parainfluenza virus (hPIV)3) and Rubulavirus (simian virus (SV)5, SV41, mumps virus and hPIV2) circumvent the interferon (IFN) response by inhibiting IFN signaling. The responsible genes were mapped to the C gene for SeV and the V gene for rubulaviruses. On the other hand, wild type measles viruses isolated from clinical specimens suppress production of IFN, although responsible viral factors remain to be identified. Both human and bovine respiratory syncytial viruses (RSVs) counteract the antiviral effect of IFN with inhibiting neither IFN signaling nor IFN production. Bovine RSV NS1 and NS2 proteins cooperatively antagonize the antiviral effect of IFN. Studies on the molecular mechanism by which viruses circumvent the host IFN response will not only illustrate co-evolution of virus strategies of immune evasion but also provide basic information useful for engineering novel antiviral drugs as well as recombinant live vaccine.

Base Sequence↗

PubMed2001

Clinical significance of autoantibody to hepatocyte membrane antigen in type 1 autoimmune hepatitis.

OBJECTIVE: By using HepG2 as flow cytometry target, we have reported that autoantibody to hepatocyte membrane antigen (anti-HMA) was frequently found in autoimmune hepatitis (AIH) patients. In this study, we have examined this autoantibody in relation to clinical features in these patients. METHODS: HepG2 cells were incubated with diluted serum and subsequently with FITC-conjugated antihuman immunoglobulin. The results were expressed as relative fluorescence intensity. The prevalence of anti-HMA was estimated by setting the upper limit of mean +/- 3 SD obtained from healthy subjects. RESULTS: We found that the mean relative fluorescence intensity was 1.67+/-0.5 in AIH with low serum ALT level (group 1 AIH), 4.20+/-1.9 in AIH with high serum ALT level (group 2 AIH), and 1.92+/-0.9 in age-matched chronic hepatitis C virus-positive patients. Their positive rate was 37.5% (three of eight) in group 1 AIH, 95.0% (19 of 20) in group 2 AIH, and 33.3% (four of 12) in chronic hepatitis C patients. In 12 group 2 AIH patients, their mean relative fluorescence intensity was significantly decreased during immunosuppressive therapy. The association between serum ALT level and anti-HMA was confirmed by the facts that a significant direct quantitative relationship existed between these two levels and by serial studies of anti-HMA in four AIH patients. Anti-HMA was also detected in five non-B, non-C hepatitis patients having clinical features resembling those of AIH. CONCLUSIONS: The present results have shown that the anti-HMA was tightly associated with the degree of hepatocyte inflammation and that the measurement of anti-HMA may have some advantage in clinical evaluation of some of non-B, non-C hepatitis patients.

Adult↗

PubMed2001

Distribution of archaea in a black smoker chimney structure.

Archaeal community structures in microhabitats in a deep-sea hydrothermal vent chimney structure were evaluated through the combined use of culture-independent molecular analyses and enrichment culture methods. A black smoker chimney was obtained from the PACMANUS site in the Manus Basin near Papua New Guinea, and subsamples were obtained from vertical and horizontal sections. The elemental composition of the chimney was analyzed in different subsamples by scanning electron microscopy and energy-dispersive X-ray spectroscopy, indicating that zinc and sulfur were major components while an increased amount of elemental oxygen in exterior materials represented the presence of oxidized materials on the outer surface of the chimney. Terminal restriction fragment length polymorphism analysis revealed that a shift in archaeal ribotype structure occurred in the chimney structure. Through sequencing of ribosomal DNA (rDNA) clones from archaeal rDNA clone libraries, it was demonstrated that the archaeal communities in the chimney structure consisted for the most part of hyperthermophilic members and extreme halophiles and that the distribution of such extremophiles in different microhabitats of the chimney varied. The results of the culture-dependent analysis supported in part the view that changes in archaeal community structures in these microhabitats are associated with the geochemical and physical dynamics in the black smoker chimney.

Archaea↗

PubMed2001

Soy protein hydrolyzate with bound phospholipids reduces serum cholesterol levels in hypercholesterolemic adult male volunteers.

This study was done to evaluate the effects of soy protein hydrolyzate with bound phospholipids (c-SPHP), on the serum cholesterol levels in hypercholesterolemic subjects over a three-month period. Subjects were Taiwanese adult male volunteers whose serum total cholesterol levels were above 220 mg/dl. Twenty-one subjects were divided into three groups randomly, and each group was given c-SPHP zero, 3, or 6 g per day. Test diets were orally administered in a powdered drink form that contained c-SPHP or casein hydrolyzate (placebo). The subjects were given the test diet four times daily. The study consisted of a two-week pre-feeding period, a three-month feeding period, followed by a two-week post-feeding period. After 3 months of c-SPHP administration, 3 g per day, serum total cholesterol decreased significantly from the initial level (15.0%, p<0.01) and compared with the placebo group (p<0.05). Furthermore, LDL-cholesterol decreased significantly (27.7%, p<0.01) and the LDL/HDL ratio also decreased significantly (47.4%, p<0.01) from the initial levels. These effects of c-SPHP were dose-dependent. This study suggests that c-SPHP has remarkable improving effects on the serum cholesterol levels in hypercholesterolemic subjects.

Adult↗

PubMed2001

Effects of adenosine 5'-triphosphate and growth hormone on cellular H+ transport and calcium ion concentrations in cloned bovine mammary epithelial cells.

The present experiment was carried out to investigate the effects of exogenous adenosine 5'-triphosphate (ATP) and growth hormone (GH) on cellular H(+) efflux rate (extracellular acidification rate) and Ca(2+) concentration ([Ca(2+)](c)) in cloned bovine mammary epithelial cells (bMEC) raised from the mammary gland of a 26-day-pregnant Holstein heifer. Perifusion of 2-day cultured cells with a medium containing ATP (10, 100 and 1000 micromol/l) for 30 min caused a significant and concentration-dependent increase in the cellular H(+) efflux rate. ATP application (100 micromol/l) caused a transient and large increase in [Ca(2+)](c) in all cells. In contrast, perifusion with a medium containing bovine GH at 10, 50 and 250 ng/ml for 30 min caused a significant decrease in the cellular H(+) efflux rate in a concentration-dependent manner. However, bovine GH application (50 ng/ml) caused a small decrease followed by an increase, in some cases, in [Ca(2+)](c). In bMEC treated with lactogenic hormones (1 microgram/l prolactin, 1 nmol/ml dexamethasone and 5 microgram/ml insulin) for 2 days, the increased H(+) efflux rate induced by ATP was significantly reduced, whereas the negative response induced by GH was inversely and significantly changed to the positive. Treatment of the cells with lactogenic hormones reduced the increase in [Ca(2+)](c) induced by ATP stimulation, while it enhanced the increase in [Ca(2+)](c) induced by GH stimulation. Application of ATP or GH did not cause any significant changes in [pH](c). Treatment with lactogenic hormones enhanced GH receptor (GHR) transcription that was determined by RT-PCR. From these results, we conclude that exogenous application of ATP and GH causes prompt and significant responses in H(+) transport and [Ca(2+)](c) that were significantly changed in the opposite direction by the treatment with lactogenic hormones. The lactogenic hormone treatment also enhanced GHR transcription, which may change post-receptor signal transduction systems for both agents in the bMEC.

Adenosine Triphosphate↗

PubMed2001

Blood pressure, serum cholesterol concentration and their related factors in urban and rural elderly of Ho Chi Minh City.

In Vietnam, information about blood pressure, serum lipids and their factors is limited. To obtain some of this information, a cross sectional nutrition survey was carried out in an urban and rural area of Ho Chi Minh City with 217 participants aged 60-69 y (148 females and 69 males). Anthropometry and blood pressure were measured. For three consecutive weekdays, 24 h dietary recalls were performed. Single 24 h urine was collected for sodium and potassium analysis. A fasting blood sample was taken and biochemical parameters were measured. Results indicate a high percentage of hypertension in urban (female: 35.5%, male: 43.8%) and rural areas (female: 22.2%, male: 35.1%). Blood pressure was correlated with body mass index (BMI) and 24 h urinary sodium-to-potassium (Na/K) ratio. A high prevalence of serum total cholesterol (TC) above 220 mg/dL (female: 55.3%, male: 31.3%) and overweight (female: 34.2%, male: 25.0%) were observed in urban residents. By contrast, 5.6% and 24.3% of rural females and males respectively had TC below 150 mg/dL and both genders had the same prevalence of underweight (32.4%). TC was positively correlated with body weight, BMI, dietary protein and dietary lipids. Overweight might be a major risk factor for hypertension in our urban elderly. A high Na/K intake ratio might be a risk factor for hypertension in both areas. The high prevalence of elevated TC in the urban area might to be related to the high lipid intake, and the high prevalence of low TC in the rural area might to be related to the low lipid intake.

Aged↗

PubMed2001

[Critical pathway for the treatment of acute myelogenous leukemia].

Based on analysis of data from 10 patients newly diagnosed as having acute myelogenous leukemia (AML), we developed a critical pathway (CP) to prevent infection and thus shorten the period of hospitalization. This CP shows laboratory test results, vital signs, chemotherapy regimen, concomitant supportive care and oral medications, gargling with antiseptic mouthwash, other anti-infection measures, diet, room conditions, patient education in anti-infection measures, outcome, and variance on the vertical axis and time on the horizontal axis. After introduction of the CP, 9 of the newly diagnosed AML patients did not experience severe treatment-related complications during a mean hospitalization of 29 days until remission and 95 days until discharge. These results suggest that the present CP makes it possible to shorten the hospital stay, reduce treatment costs, and improve the quality of life of AML patients.

Acute Disease↗

PubMed2001

[Efficacy of cibenzoline in the termination and long-term prevention of paroxysmal atrial fibrillation: analysis based on the time of onset].

OBJECTIVES: The efficacy of cibenzoline was assessed in the termination and long-term prevention of paroxysmal atrial fibrillation in relation to the time of onset in a series of patients with paroxysmal atrial fibrillation. METHODS: Study of the termination included 92 patients (63 males, 29 females, mean age 64 +/- 12 years) and study of long-term prevention included 106 patients (77 males, 29 females, mean age 64 +/- 11 years; mean follow-up 32.7 +/- 18.8 months). Paroxysmal atrial fibrillation was classified into 3 types based on the time of onset: day type (AM 7:00-PM 5:00), night type (PM 5:00-AM 7:00) and mixed type (anytime). Successful termination was defined as pharmacological cardioversion within 30 min of the intravenous administration of 70 mg cibenzoline and efficacy of long-term prevention was presented as the event-free ratio of patients after oral administration of 300 mg/day cibenzoline. RESULTS: Successful pharmacological termination was achieved in 66.7% of the day type (n = 24), 70.0% of the night type (n = 48), and 41.6% of the mixed type (n = 20). There was a significantly higher success in the day type (p < 0.05), and tendency to success in the night type (p = 0.079) compared to the mixed type. The event-free ratios at 1, 3, 6, 12, 24 months after oral administration were 84.6%, 76.9%, 73.1%, 65.4%, 61.5% in the day type (n = 26), 92.0%, 80.0%, 80.0%, 72.0%, 60.0% in the night type (n = 25), and 81.8%, 61.8%, 47.3%, 30.9%, 23.6% in the mixed type (n = 55), respectively. Significantly higher success was achieved at 24 months in the day type and the night type compared to the mixed type (p < 0.05). CONCLUSIONS: Termination and long-term prevention of paroxysmal atrial fibrillation by cibenzoline has a high degree of efficacy in patients with both day and night onset of paroxysmal atrial fibrillation.

Administration, Oral↗

PubMed2001

Decreases in phenytoin hydroxylation activities catalyzed by liver microsomal cytochrome P450 enzymes in phenytoin-treated rats.

Phenytoin, 5,5-diphenylhydantoin, is a widely used anticonvulsant agent with a variety of toxicities, including drug interactions. The formation of four oxidative metabolites, 4'-hydroxylated (4'-HPPH), 3'-hydroxylated (3'-HPPH), a catechol (3',4'-diHPPH), and the 3',4'-dihydrodiol form of phenytoin was examined in rat liver microsomes. In 11 cDNA-expressed rat P450 enzymes tested, CYP2C6 had the highest activities in 4'- and 3'-HPPH formation from phenytoin, followed only by CYP2C11. In contrast, CYP2C11 had high activity for 3',4'-diHPPH formation from 4'-HPPH, followed by CYP2C6. The rates of 4'-HPPH and 3',4'-diHPPH formation from phenytoin in liver microsomes in the presence of NADPH were significantly decreased by oral administration of phenytoin (300 mg/kg for 20 days) to rats, despite the increase in P450 contents. However, the cumene hydroperoxide-supported formation of 3',4'-dihydrodiol and 4'-HPPH from phenytoin was induced by phenytoin administration. Hydrogen peroxide formation in reaction mixtures with NADPH was induced by the administration of phenytoin; however, the coupling ratio of phenytoin oxidation was decreased in phenytoin-induced liver microsomal P450 systems. These results suggested that phenytoin could not stimulate its own apparent oxidative metabolism by liver P450s induced with phenytoin administration. The increase of unmetabolized phenytoin and byproducts of oxygen generated in the phenytoin-induced liver microsomal P450 system may be involved in phenytoin-related drug toxicity.

Animals↗

PubMed2001

Involvement of microsomal cytochrome P450 and cytosolic thymidine phosphorylase in 5-fluorouracil formation from tegafur in human liver.

Recently, we have reported that tegafur, an anticancer agent, is biotransformed into active drug 5-fluorouracil (5-FU) by cytochromes P450 1A2, 2A6, and 2C8 in human liver microsomes (T. Komatsu et al., Drug Metab. Dispos, 28: 1457-1463, 2000). Because the conversion of tegafur into 5-FU has also been reported to be catalyzed by cytosolic thymidine phosphorylase (dThdPase), the involvement of human liver microsomes and cytosol and individual differences in 5-FU formation from tegafur were investigated. In 14 human samples, the mean rates of 5-FU formation in liver microsomes were 5-fold and 2-fold higher than those in liver cytosol at substrate concentrations of 100 microM and 1 mM tegafur, respectively. In the presence of 5-chloro-2,4-dihydroxypyridine, a dihydropyrimidine dehydrogenase inhibitor, the rates of 5-FU formation by the combination of liver microsomes and cytosol showed 5- and 3-fold interindividual differences at 100 microM and 1 mM tegafur, respectively. Kinetic analysis of human liver cytosolic 5-FU formation indicated an apparent higher Km value (16 +/- 4 mM) than that of liver microsomes (1.8 +/- 0.3 mM) with similar Vmax values. Human liver cytosolic 5-FU formation was confirmed to be catalyzed by dThdPase with correlation and chemical inhibition studies. These results suggested that 5-FU formation from tegafur in human liver was mainly catalyzed by microsomal P450 at low concentrations of tegafur, but the contribution of cytosolic 5-FU formation by dThdPase would be important at high concentrations.

Antimetabolites, Antineoplastic↗

PubMed2001

Rat cytochrome p450 1A and 3A enzymes involved in bioactivation of tegafur to 5-fluorouracil and autoinduced by tegafur in liver microsomes.

Tegafur, an anticancer prodrug, is reported to be bioactivated to 5-fluorouracil (5-FU) by cytochrome P450 (P450) enzymes. Liver microsomal P450 enzymes involved in the biotransformation of tegafur into 5-FU in rats and the effect of tegafur in vivo on P450 levels in rats were investigated. Of 12 cDNA-expressed rat P450 enzymes tested, CYP1A2, CYP3A1, and CYP2C11 had high 5-FU formation rates from 100 microM and 1.0 mM tegafur concentrations. The contributions of CYP1A, CYP2C, and CYP3A enzymes to 5-FU formation in male rat liver microsomes were supported by immunoinhibition studies. 5-FU formation from tegafur, at substrate concentrations of 100 microM and 1.0 mM, was increased by intraperitoneal treatment of tegafur (50 mg/kg for 5 days) as well as by beta-naphthoflavone, phenobarbital, and dexamethasone. Orally administered tegafur (100 mg/kg daily for 20 days) caused the induction of CYP2B (5-fold) and of CYP1A and CYP3A (approximately 2-fold) and of 5-FU formation (approximately 2-fold) in rat liver microsomes. These results suggest that CYP1A and CYP3A enzymes, autoinduced by tegafur, have important roles in 5-FU formation from tegafur in rat liver microsomes. Coadministration of tegafur and P450-inducing drugs could markedly enhance the biotransformation of tegafur into 5-FU via P450 induction.

Animals↗

PubMed2001

Enhancement of matrix metalloproteinase (MMP)-2 activity in gingival tissue and cultured fibroblasts from Down's syndrome patients.

OBJECTIVES: To identify one of the possible factors responsible for periodontal disease in Down's syndrome (trisomy 21) patients, we studied the enzyme activity and the mRNA expression pattern of matrix metalloproteinases (MMPs) of cultured gingival fibroblasts (GF) and fresh gingival tissues. MATERIALS AND METHODS: Gingival tissue was used as the cell source and was biopsied at the time of dental treatment from nine patients with Down's syndrome and nine non-Down's controls. GF were cultivated in serum-free media for analyses of their MMP activities at the transcription or the protein level. The MMP activities in the supernates were measured by gelatin impregnated zymography. Relative levels of MMP mRNA from the cultured GF or freshly isolated gingival tissues were determined using the reverse transcription polymerase chain reaction (RT-PCR). RESULT AND CONCLUSIONS: The production of the active type of MMP-2 in GF from Down's syndrome patients (D-GF) was found to be significantly higher (P < 0.05) than that of the control GF (C-GF) at the protein level. The mRNA expressions of membrane-type I MMP (MT1-MMP) and MMP-2 in D-GF were constitutively augmented when compared with those of C-GF. These findings suggest that specific increase of the active form of MMP-2 in D-GF may possibly be due to the concomitant expression of MT1-MMP in the cultured cells, and this could be related to the pathogenesis of gingivitis/periodontitis associated with Down's syndrome patients.

Adolescent↗

PubMed2001

[Efficacy of pilsicainide for the long-term prevention of paroxysmal atrial fibrillation: analysis based on the time of onset].

OBJECTIVES: This study evaluated the efficacy of long-term pilsicainide therapy to maintain sinus rhythm in patients with paroxysmal atrial fibrillation in terms of the time of onset. METHODS: A total of 81 patients (57 men, 24 women, mean age 65 +/- 11 years) were given pilsicainide (150 mg/day) after cardioversion. Paroxysmal atrial fibrillation was divided into three types by the time of onset: the day type (AM 7:00-PM 5:00, n = 13), the night type (PM 5:00-AM 7:00, n = 12) and the mixed type (n = 56). Mean follow-up period was 35.4 +/- 16.1 months. RESULTS: There was a higher incidence of hypertension in the day type (38.5%) and the mixed type (48.2%) than in the night type (8.3%) (p < 0.05). The periods for maintenance of sinus rhythm in the day type, the night type and the mixed type were 15.7 +/- 5.0, 9.9 +/- 2.7 and 5.7 +/- 1.3 months, respectively, with a significant difference between the day type and the mixed type (p < 0.01). Actuarial event free-rates at 1, 3, 6, 9 and 12 months were 76.9%, 69.2%, 61.5%, 53.8% and 53.8% respectively, in the day type, 83.3%, 66.7%, 58.3%, 33.3% and 33.3%, respectively, in the night type and 58.9%, 37.5%, 26.8%, 25.0% and 21.4%, respectively, in the mixed type. There was a significant difference in the rate at 12 months between the day type and the mixed type (p < 0.05). CONCLUSIONS: These results suggest that pilsicainide has a high degree of efficacy for maintaining normal sinus rhythm in patients with the day type onset of paroxysmal atrial fibrillation.

Aged↗

PubMed2000

Statistical analysis of the 5' untranslated region of human mRNA using "Oligo-Capped" cDNA libraries.

We constructed 34 types of human "full-length enriched" and "5'-end enriched" cDNA libraries based on the "Oligo-Capping" method. We randomly picked and sequenced 10,000 clones from these libraries. BLAST analysis showed that about 50% of the cDNAs were identical to known genes. Among them, we selected 954 species of cDNA that should represent the entire sequence from the mRNA start sites. Compared with previously reported sequences, they were on average 45 bp longer in the 5'-end. Using these cDNA data, we statistically analyzed the sequence features of the 5'UTR. The average length of the 5'UTR was 125 bp, and there was little correlation with the corresponding mRNA length (correlation coefficient = 0.26). Of the 954 species of 5'UTR, 459 contained no in-frame terminator codon, which is against the common belief. Two hundred seventy-eight species contained at least one ATG codon upstream of the initiator ATG codon. We identified 569 upstream ATGs, in total, 63% of which adequately satisfied Kozak's criteria. These findings are contrary to the typical translation initiation model, which states that translation is initiated from the "first" ATG codon.

5' Untranslated Regions↗

PubMed2000

A giant cell angiofibroma involving 6q.

Giant cell angiofibroma, a recently proposed new clinicopathological entity, arises exclusively in the orbit in adults and histologically exhibits features intermediate between those of giant cell fibroblastoma and solitary fibrous tumor. In a typical case of giant cell angiofibroma, abnormalities of chromosome 6 with a common pattern involving 6q13 were detected together with various other chromosomal aberrations. To our knowledge, this is the first reported case of giant cell angiofibroma demonstrating chromosomal abnormalities.

Angiofibroma↗

PubMed2000

Heart rate variability during massive hemorrhage and progressive hemorrhagic shock in dogs.

PURPOSE: To investigate the sequential changes in heart rate (HR), autonomic nervous activity presented by the spectral analysis of heart rate variability (HRV), hemodynamics and metabolism during massive hemorrhage and progressive hemorrhagic shock in dogs. METHODS: Twelve dogs were subjected to acute massive hemorrhage until mean arterial pressure (MAP) reached 50 mm Hg. Then bleeding was stopped and they were allowed to reach a plateau phase. They were divided, post hoc, into bradycardic or tachycardic groups according to their HR response to the acute massive hemorrhage. After reaching a plateau phase, the dogs were further bled to keep their MAP around 50 mmHg (progressive hemorrhagic shock). Their heart rate power spectra were quantified into low-frequency (LF) (0.04-0.15 Hz) and high-frequency (HF) (0.15-0.4 Hz) components. RESULTS: In the bradycardic group, both LF and HF increased after massive hemorrhage, but during progressive hemorrhagic shock these components decreased while HR increased. In the tachycardic group, LF increased after massive hemorrhage, but during progressive hemorrhagic shock LF decreased with continuous suppression of HF CONCLUSION: Massive hemorrhage caused two types of HR response: bradycardia and tachycardia. The HRV profile showed differential autonomic characteristics, and could be a valuable tool in assessing various degrees of hemorrhagic shock.

Animals↗