Biomedical subjects

Hirofumi Harada

Publications and source records attributed to Hirofumi Harada.

8 recordsLinked to original sources

PubMed2005

Orexinergic projections to the cat midbrain mediate alternation of emotional behavioural states from locomotion to cataplexy.

Orexinergic neurones in the perifornical lateral hypothalamus project to structures of the midbrain, including the substantia nigra and the mesopontine tegmentum. These areas contain the mesencephalic locomotor region (MLR), and the pedunculopontine and laterodorsal tegmental nuclei (PPN/LDT), which regulate atonia during rapid eye movement (REM) sleep. Deficiencies of the orexinergic system result in narcolepsy, suggesting that these projections are concerned with switching between locomotor movements and muscular atonia. The present study characterizes the role of these orexinergic projections to the midbrain. In decerebrate cats, injecting orexin-A (60 microm to 1.0 mm, 0.20-0.25 microl) into the MLR reduced the intensity of the electrical stimulation required to induce locomotion on a treadmill (4 cats) or even elicit locomotor movements without electrical stimulation (2 cats). On the other hand, when orexin was injected into either the PPN (8 cats) or the substantia nigra pars reticulata (SNr, 4 cats), an increased stimulus intensity at the PPN was required to induce muscle atonia. The effects of orexin on the PPN and the SNr were reversed by subsequently injecting bicuculline (5 mm, 0.20-0.25 microl), a GABA(A) receptor antagonist, into the PPN. These findings indicate that excitatory orexinergic drive could maintain a higher level of locomotor activity by increasing the excitability of neurones in the MLR, while enhancing GABAergic effects on presumably cholinergic PPN neurones, to suppress muscle atonia. We conclude that orexinergic projections from the hypothalamus to the midbrain play an important role in regulating motor behaviour and controlling postural muscle tone and locomotor movements when awake and during sleep. Furthermore, as the excitability is attenuated in the absence of orexin, signals to the midbrain may induce locomotor behaviour when the orexinergic system functions normally but elicit atonia or narcolepsy when the orexinergic function is disturbed.

Animals↗

PubMed2005

Effects of injecting GABAergic agents into the medullary reticular formation upon swallowing induced by the superior laryngeal nerve stimulation in decerebrate cats.

The purpose of this study was to elucidate the role of the GABAergic system in the medullary reticular formation (MRF) in the control of swallowing. In acutely decerebrated cats (n = 12), swallowing was induced by electrical stimulation (0.3-6 V at 10-20 Hz for 10-20 s every minute) applied to the superior laryngeal nerve (SLN). The stimulus intensity was adjusted so that swallowing was induced two or four times during the period of the stimulation. Bicuculline, a GABA(A) receptor antagonist, was then injected (0.10-0.15 microl, 5 mM) into the MRF through a stereotaxically placed glass micropipette. In a total of 62 injections, 19 injections (30.6%) increased the frequency of SLN-induced swallowing when it was injected into the lateral part of the MRF corresponding to the nucleus reticularis parvocellularis (NRPv). In eight of the effective injections (42.1%) which increased the frequency of SLN-induced swallowing, SLN stimulation also induced coughing. With two injections, stimulation of the SLN-induced coughing but not facilitation of swallowing. On the other hand, an injection of 0.10-0.15 microl of 5 mM muscimol, a GABA(A) receptor agonist, into the NRPv decreased the frequency of SLN-induced swallowing. These results suggest that the NRPv neurons which are responsible for evoking swallowing are under the tonic inhibitory control of the GABAergic system.

Animals↗

PubMed2005

Prognosis for sudden sensorineural hearing loss: a retrospective study using logistical regression analysis.

Sudden sensorineural hearing loss (SSNHL) remains a controversial problem with respect to etiology and the factors that might predict prognosis. We used logistical regression analysis to determine which factors are most strongly related to outcome for patients with SSNHL. In so doing, we employed a retrospective chart-review study. The study group consisted of 296 patients (296 ears). The outcome of SSNHL was cured (full recovery) in 64, recovered (partial recovery) in 175, and no change in 57. We performed separate analyses on those in the no-change and partial-recovery groups and on those in the no-change and full-recovery groups. The following factors were studied as explanatory variables: age; number of days until presentation; vestibular symptom; initial mean hearing level at 0.25 kHz, 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz; and treatments (steroids, satellite ganglion block). In the first analysis, for patients in the no-change and recovered groups, the factors most strongly related to outcome were the number of days until presentation and age. The second analysis, for the nochange and cured groups, revealed that the number of days until presentation, vestibular symptom, age, and initial mean hearing level were most strongly related to outcome. Our results will increase the ability to predict the outcome for SSNHL.

Adolescent↗

PubMed2003

Progressive improvement of prognosis for patients with gastric cancer (dynamic stage grouping) with increasing survival interval from initial staging: how much longer can a given survivor expect to live?

BACKGROUND: The prognosis in gastric cancer is usually defined at the time of presentation. Prognosis, however, is a variable that alters with time. Once a patient has survived for 1 year, the prognosis will change. This study examines this variable in patients who have survived from 1 to 5 years after operation. METHODS: Of 1468 patients with gastric cancer, the next 5-year survival (5YS) of patients who already survived for 1, 2, 3, 4, and 5 years after the initial operation was examined, ie, for patients who have survived 1 year, the 5YS (the 6-year survival from operation) was calculated. Similar survival was determined for patients who had survived more than 2, 3, 4, or 5 years and reported according to stage. RESULTS: In patients who survived 2 years, the next 5YS from that time of patients in stage III a stage was similar to that in stage II, and was similar to the 5YS of patients in stage II at the time of diagnosis. In patients who survived 3, 4, or 5 years, the next 5YS from that time of patients in stage III b and stage III a was similar to that of stage II, and subsequently improved. Similarly, the relationship between stage and survival was disordered subsequently with the passage of time. Similar improvement in survival such that 5YS from the 3rd, 4th, and 5th postoperative year approximated that of the survival of patients at an earlier stage at the time of diagnosis. CONCLUSIONS: Survival is not only stage-dependent at the time of diagnosis but dependent on the length of survival from the initial operation. Progressive improvement in subsequent 5YS appears to approximate survival of lower-stage disease with the passage of time.

Adult↗

PubMed2003

Olfactory event-related potentials in normal subjects and patients with smell disorders.

We developed a device to record olfactory event-related potentials (OERP) from the human scalp. Methyl-cyclopentenolone was used as the odorant element. A total of 50 stimuli were delivered. Each stimulus lasted 0.5 sec and was delivered once every three inspirations. Normal OERPs were obtained with this device. The positive peak latencies were approximately 350 msec (P1) and 700 msec (P2), respectively. OERPs were also recorded in 40 patients with smell disorders. A positive response at about 300-400 msec was recorded in 7 patients (all females, 15-59 years old). The other 33 patients showed no response. The high potential area of this positive peak was located in the centro-occipital region of the scalp. The latency and the high potential area of this peak were similar to P1 recorded in normal subjects. The source of this peak was considered identical to that of P1. This may be a response to the trigeminal nerve during odor administration. P2 was not recorded in the patients with smell disorders. P2 may therefore be a response to the olfactory nerve.

Adolescent↗

PubMed2002

Electroencephalographic changes during intravenous olfactory stimulation in humans.

The intravenous olfaction test with thiamin propyl disulfide (TPD) is a simple procedure widely used in Japan. An olfactory stimulus is provided by intravenous injection of TPD (2 ml) over the course of 20 sec. The subject smells n-propyl mercaptan (a decomposition product of TPD discharged from the blood into alveoli) in expired air after treatment. In this preliminary study we recorded electroencephalograms (EEGs) in normal subjects during three stages: 1) eyes-closed rest (prestimulus), 2) olfactory sensation after TPD injection, and 3) disappearance of sensation. In each of these stages, we calculated and compared EEG powers according to the band components of each electrode position. This study was designed a) to evaluate by frequency analysis EEG changes during olfactory sensation after TPD injection, and b) to identify the most significant changes in EEG power according to frequency band and electrode location. During the intravenous olfactory stimulation, alpha 2 and beta 2 waves were activated over the frontal and temporal regions. After disappearance of olfactory sensation, these waves decreased in the same regions. EEG powers returned to prestimulus levels.

Adult↗

PubMedDate not supplied

Does body mass index (BMI) influence morbidity and long-term survival in gastric cancer patients after gastrectomy?

BACKGROUND/AIMS: The long-term survival of patients with gastric cancer is governed by various factors, such as the clinical stage of the cancer, the patient's nutritional state, and the treatment and may be governed by the volume of intraperitoneal adipose tissue. The aim of this study is to clarify the relationship between the degree of the patients' body mass index and their long-term survival. METHODOLOGY: Gastric cancer patients who had undergone a gastrectomy with D2-lymphadenectomy and with resection A and B according to the criteria of the Japanese Research Society for Gastric Cancer Rules were subgrouped into those patients with a body mass index < 0.185 (the lower body mass index group) and those patients with a body mass index > 0.210 (the higher body mass index group). The patient's morbidity and long-term survival rate was retrospectively compared between the 2 groups. RESULTS: A significantly longer mean survival rate was observed for the lower body mass index group in stage 2 (1667 vs. 1322 days, P = 0.0240). Also, a significantly longer mean survival rate was observed for the higher BMI group in stage 3a (1431 vs. 943, P = 0.0071). CONCLUSIONS: The body mass index is one of the prognostic factors of stage 2 and stage 3a gastric cancer. However, it does not appear to be useful for determining the prognosis of stage 1a, 1b, 3b, and 4a gastric cancers.

Adult↗

PubMedDate not supplied

Does the surgical stress associated with palliative resection for patients with incurable gastric cancer with distant metastasis shorten their survival?

BACKGROUND/AIMS: In cases of incurable stage IV gastric cancer with distant metastases, surgical treatment has usually consisted merely of palliation. The effect of palliative resection in these highly advanced cases remains controversial. Palliative resection may be prohibited by the potential disadvantages of surgical stress. METHODOLOGY: Over the past 23 years, 382 stage IV incurable gastric cancer patients with distant metastases were classified into a resection group (group R) whose subjects underwent a palliative resection of the primary tumor and the non-resection group (group N) who were treated without resection of primary tumor. In order to exclude patients with very poor prognosis due to irresectability even if trying to resect, we restricted the subjects to patients who survived more than 30 and 60 days and some months and estimated the mean survival. Cumulative survival rates were calculated by using the Kaplan-Meier method, and the mean survivals of groups R and N were compared. RESULTS: A significantly longer mean survival was observed in group R than in group N (381 vs. 181 days, P<0.0001). Restricting the subjects to patients who survived more than 30 and 60 days, there is also a significant difference between the mean survival of group R and that of group N. However, restricting the subjects to patients who survived more than 300 days, no significant difference was seen between the two groups. The rate of hospital death was higher in group N than in group R (15.9% vs. 3.4%) CONCLUSIONS: Palliative resection of the primary tumor in stage IV gastric cancer is meaningful in view of hospital stay, long-term survival, and satisfaction with the treatment. We should resect the primary tumor in cases in which it is resectable.

Female↗