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Biomedical subjects

T Tsuboi

Publications and source records attributed to T Tsuboi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Inhibitory effect of an intellectual task on breathing after voluntary hyperventilation.

We investigated the effects of an intellectual task on posthyperventilation (PHV) breathing by using a video game. Eight normal subjects were placed in a supine positions. The game task by itself led to increase ventilation compared with the control tasks via an increase in the average inspiratory flow rate (P < 0.01) and the respiratory frequency (P < 0.001). After hypocapnic voluntary hyperventilation (VHV), the task led to a decrease in the 1-min PHV breathing level compared with the control tasks after VHV [after VHV, first 60 s average minute ventilation while watching television and while playing a video game are 5.54 +/- 2.91 (SD) and 2.05 +/- 1.40 l/min, respectively; P < 0.01]. Only one subject showed PHV apnea for at least 10 s during the control protocol, whereas seven of the same eight subjects showed PHV apnea while performing the task. After isocapnic VHV, the task still led to a decrease in PHV breathing compared with the control tasks. However, this decrease was smaller than in the hypocapnic studies and was only significant during the first 15 s of recovery. These results suggest that increased activity in the higher centers of the central nervous system has an inhibitory effect on PHV breathing at a time when the effects of short-term potentiation after VHV, hypocapnia, and perhaps other mechanisms would be expected to be acting on breathing.

Adult↗
PubMed1996

Effects of NCPAP therapy on fibrinogen levels in obstructive sleep apnea syndrome.

In patients with obstructive sleep apnea syndrome (OSAS), the blood coagulation system may contribute to an increased risk of cardiovascular events, which occur most frequently in the morning. Nasal continuous positive airway pressure (NCPAP) treatment can improve the mortality of patients with OSAS. We measured the plasma fibrinogen concentration, which is an independent risk factor for cardiovascular events, in the afternoon (3:30 P.M.) and the next morning upon awakening (8:30 A.M.) in 11 patients with OSAS (apnea and hypopnea index > 20) before and after NCPAP therapy. We also measured the hematocrit, the C-reactive protein, and the total plasma protein at the same time. The plasma fibrinogen and hematocrit levels in the morning (298 +/- 16 mg/dl and 48.5 +/- 1.5%, mean +/- SEM) were significantly higher than on the previous afternoon (275 +/- 14 mg/dl and 46.6 +/- 1.3%) (fibrinogen, p < 0.02; hematocrit, p < 0.005). The whole blood viscosity (WBV) at a shear rate of 208 inverse seconds, which can be predicted based on the hematocrit and total plasma protein, was also significantly higher in the morning (4.98 +/- 0.20/s) than in the afternoon (4.73 +/- 0.17/s) (p < 0.005). These increases in the plasma fibrinogen concentration and the WBV in the morning disappeared after NCPAP treatment. The attenuation of morning increases in the plasma fibrinogen concentration and WBV induced by NCPAP treatment may contribute to an overall improvement in the mortality from cardiovascular events in patients with OSAS.

Adult↗
PubMed1996

[Outcome of long-term nasal intermittent positive pressure ventilation in 41 patients with hypercapnic respiratory failure].

Nasal intermittent positive pressure ventilation (NIPPV) is widely used in domiciliary treatment of chronic ventilatory disorders. The outcomes of long-term NIPPV were analyzed in 41 patients with hypercapnic respiratory failure due to pulmonary tuberculosis sequelae (PTS; n = 17), neuromuscular disease (NMD; n = 8), kyphoscoliosis (KS; n = 7), chronic obstructive pulmonary disease (COPD; n = 6), and miscellaneous diseases (n = 3). Twenty-seven patients with chronic conditions but without acute exacerbations began receiving NIPPV, and fourteen patients began receiving NIPPV after an acute exacerbation. Outcome measures included the probability of continuing NIPPV, survival after starting NIPPV, survival after starting home oxygen therapy (HOT), arterial blood gases, nocturnal oxygen saturation, pulmonary function, and the number of hospital days. Two patients with PTS died, 7 and 40 months after starting NIPPV. Two patients (one with PTS and one with COPD) switched from NIPPV to intermittent positive pressure ventilation via a tracheostomy. The condition of one patient with NMD improved and NIPPV was discontinued. The three-year and five-year probabilities of continuing NIPPV in all patients were 82%, and 71%, respectively. The survival rates three and five years after starting NIPPV were 97% and 85%, respectively. The survival rates one to nine years, and ten to eleven years after starting HOT were 98% and 65%, respectively. The arterial PO2 and PCO2, nocturnal oxygen saturation, vital capacity, and forced expiratory volume, in one second all improved after NIPPV was begun. NIPPV also reduced the number of hospital days, particularly in patients with KS. In conclusion, the long-term outcome of NIPPV in patients with hypercapnic respiratory failure is encouraging.

Adult↗
PubMed1996

[A patient with myotonic dystrophy who presented with chest roentgenographic abnormalities and alveolar hypoventilation].

A 52-year-old man had been asymptomatic except for nasal speech since his third decade of life. A chest roentgenogram obtained during a health screening one year before admission revealed elevation of the right hemidiaphragm and infiltrates in the right lower lung field. Because the pulmonary shadows had gradually increased, he was admitted to the hospital, for further examination. Based on physiological findings and on the results of electromyography, myotonic dystrophy was diagnosed. The chest roentgenographic abnormalities were regarded as resulting from complications of this disease. Arterial blood gas analysis showed hypercapnic hypoxia and a spirogram showed that the vital capacity and maximum voluntary ventilation were about half of their respective predicted values. The hypercapnic ventilatory response was also abnormally low. An overnight study of oxygen saturation showed episodes of marked desaturation, and polysomnography revealed central sleep apnea. Inhalation of capsaicin showed an abnormally high cough threshold. Patients with undiagnosed myotonic dystrophy rarely present with chest roentgenographic abnormalities.

Electromyography↗
PubMed1996

[Temporary use of chest negative pressure ventilation to facilitate closure of a tracheal stoma before domiciliary nasal intermittent positive pressure ventilation].

A 67-year-old patient with pulmonary tuberculosis sequela had undergone a tracheostomy. The patient was receiving nasal intermittent positive pressure ventilation and the stoma failed to close. Temporary use of chest negative pressure ventilation facilitated closure of the stoma and probably shortened the patient's hospital stay. Nasal intermittent positive pressure ventilation at home was begun safely and effectively.

Aged↗
PubMed1995

The effect of fatigue caused by electrical induction or voluntary contraction on Ia inhibition in human soleus muscle.

A comparison of the effect of fatigue caused by electrical induction or voluntary contraction on Ia inhibition in human soleus muscle was investigated in fourteen healthy male subjects. The Hoffmann reflex (H reflex) was employed to elucidate the contribution of fatigue induced contraction to the Ia inhibition. A statistically significant difference (P < 0.05) in H reflex amplitude between the intermittent stimulation at 15 Hz and voluntary contraction was observed. Our study suggested that Ia inhibition in human soleus muscle, caused by electrically induced or voluntary contraction, induced differences in the number of impulses in the group Ia fibers, between the two conditions.

Adult↗
PubMed1995

Murine complement reduces infectivity of Plasmodium yoelii to mosquitoes.

The alternative pathway of complement in the mouse serum significantly reduced, but did not eliminate, the infectivity of Plasmodium yoelii to Anopheles stephensi. The reduction of the infectivity is mainly due to the inability of the zygote to transform into the ookinete in the mosquito midgut.

Animals↗
PubMed1994

Spectral analysis of electromyogram in lumbar muscles: fatigue induced endurance contraction.

In the last few years, epidemiological studies have shown correlations between the low endurance capacity of the erector spinae muscle and low back pain (LBP). In this study, the function of the erector spinae muscle and localized muscle fatigue in LBP were investigated in both LBP patients and control subjects without LBP, using surface multi-channel electromyograms (EMG). Four positions (L1, L2, L4, L5) were chosen as representative locations for the different functions of the erector spinae muscle. Median frequency (fm) parameters of an EMG power density spectrum were monitored to quantify localized muscle fatigue. This research indicated a statistically significant difference (P < 0.05) in fm parameters between the LBP patients and the control subjects. The integrated electromyogram (iEMG) signals of LBP patients were considerably higher than for the control subjects during endurance isometric contraction. Our research suggested that human fatiguing erector spinae muscle, in submaximal voluntary contractions tests, induced a different firing order of motor unit spikes between two groups.

Adult↗
PubMed1994

Hepatotrophic activity in mouse serum infected with plerocercoids of Spirometra erinacei.

To investigate the mechanism by which liver weight increases during plerocercoid infections as well as the possible existence of a hepatocyte-growth-factor (HGF)-like substance in the serum of mice infected with Spirometra erinacei plerocercoids, liver DNA synthesis was measured in vivo and in vitro. Infection with S. erinacei plerocercoids significantly stimulated DNA synthesis in mouse parenchymal hepatocytes prior to the increase in liver weight, at least partly by stimulating the induction of the salvage pathways of pyrimidine biosynthesis. Furthermore, infected mouse serum directly stimulated DNA synthesis in cultured mouse parenchymal hepatocytes. These results suggest that an HGF-like substance is present in the serum of mice infected with S. erinacei plerocercoids.

Animals↗
PubMed1994

Natural variation within the principal adhesion domain of the Plasmodium vivax duffy binding protein.

The blood-stage development of malaria parasites is initiated by the invasion of merozoites into susceptible erythrocytes. Specific receptor-ligand interactions must occur for the merozoites to first attach to and then invade erythrocytes. Because the invasion process is essential for the parasite's survival and the merozoite adhesion molecules are exposed on the merozoite surface during invasion, these adhesion molecules are candidates for antibody-dependent malaria vaccines. The Duffy binding protein of Plasmodium vivax belongs to a family of erythrocyte-binding proteins that contain functionally conserved cysteine-rich regions. The amino cysteine-rich regions of these homologous erythrocyte-binding proteins were recently identified for P. vivax, Plasmodium knowlesi, and Plasmodium falciparum as the principal erythrocyte-binding domains (C. Chitnis and L. H. Miller, J. Exp. Med. 180:497-506, 1994, and B. K. L. Sim, C. E. Chitnis, K. Wasniowska, T. J. Hadley, and L. H. Miller, Science 264:1941-1944, 1994). We report that amino acids in this critical ligand domain of the P. vivax Duffy binding protein are hypervariable, but this variability is limited. Hypervariability of the erythrocyte-binding domain suggests that this domain is the target of an effective immune response, but conservation of amino acid substitutions indicates that functional constraints limit this variation. In addition, the amino cysteine-rich region and part of the hydrophilic region immediately following it were the site of repeated homologous recombinations as represented by tandem repeat sequence polymorphisms. Similar polymorphisms have been identified in the same region of the homologous genes of P. falciparum and P. knowlesi, suggesting that there is a common mechanism of recombination or gene conversion that occurs in these Plasmodium genes.

Amino Acid Sequence↗
PubMed1993

Histometric changes in connective fibers of the lung following paraquat administration in rats.

Pulmonary fibrosis induction by paraquat was studied histometrically using an image analyzer. Rats were given a subcutaneous injection of paraquat (7 or 25 mg/kg) and autopsied 3, 6 or 9 days later. The percentage of the area of connective fibers per unit area, and lung prolyl hydroxylase activity, as a biochemical parameter, were measured. Rats treated with 25 mg/kg of paraquat showed an increase in the percentage of the area of the connective fibers per unit area and also an increase in lung prolyl hydroxylase activity 6 days later. Thus, pulmonary fibrosis was confirmed both morphologically and biochemically. It is concluded that histometric examination using an image analyzer provides a very accurate method for the evaluation of pulmonary fibrosis.

Animals↗