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Kaoru Yamazaki

Publications and source records attributed to Kaoru Yamazaki.

11 recordsLinked to original sources
PubMed2006

Distribution of longitudinal wave properties in bovine cortical bone in vitro.

The detailed spatial distributions of longitudinal ultrasonic velocity in cortical bone specimens obtained from three bovine femoral diaphysis were experimentally investigated using a pulse-echo system. The relationship between velocity, density, bone mineral density (BMD) and microstructure was investigated. Velocity was found to vary as a function of the direction of propagation and the location of the measured specimens in the bone diaphysis. A significant correlation was found between density and velocity, and between density and BMD. In some parts with plexiform structure, clear variations in velocity anisotropy were found despite no significant difference in density, BMD and microstructure.

Algorithms↗
PubMed2005

Assessment of risk factors for second hip fractures in Japanese elderly.

In an attempt to identify a cohort with a high risk of suffering a fracture of the contralateral hip (second hip fracture), we assessed patients who had suffered hip fracture. A total of 714 patients (130 men and 584 women) were prospectively followed to determine those who suffered a second hip fracture. Pathologic hip fractures and fractures that emerged from high-energy trauma were excluded from the analysis. Age, gender, Singh Index (SI), fracture type, cognitive impairment, and comorbid medical conditions were investigated as medical predictors. The 714 patients were observed for 1,579.5 person-years (mean: 2.4+/-1.4 years per patient). During the observation period, 45 second hip fractures were identified (bilateral group), giving an overall incidence of 0.029 per person-year. The annual incidence rate declined linearly from the occasion of the initial fracture. Furthermore, the second hip fracture tended to occur increasingly within 8 months after the initial hip fracture. The second hip fracture was of the same type (trochanteric or cervical) in 79% of the trochanteric and 71% of the cervical fractures. There was no significant difference in the incidence of second hip fracture by gender or age. In addition, there was no significant difference in the distribution of SI grades of the unfractured hip at the initial hip fracture between the 669 patients who had not suffered a second hip fracture (unilateral group) and the bilateral group. Cox proportional hazard regression analysis revealed that increased risk of a second hip fracture was associated with senile dementia and Parkinson's disease. We concluded that careful follow-up of hip fracture patients associated with senile dementia and Parkinson's disease might effectively prevent the incidence of a second hip fracture.

Aged↗
PubMed2005

[Mechanisms of action in bisphosphonates].

Bisphosphonates have the high affinity to hydroxyapatites and act as the inhibition of bone resorption in a low dose, while they act as the inhibition of the calcification in a high dose. In tissues, bisphosphonates adsorbing bone surface become detached by a low pH environment with bone resorption and then act on osteoclasts. In cellular events, nitrogen-containing compounds interfere with protein prenylation by inhibiting an enzyme in the HMG-CoA reductase pathway. On the other hand, non-nitrogen-containing bisphosphonates act by producing toxic analogs of ATP that cause cell death.

Bone Resorption↗
PubMed2004

[Trend of an osteoporosis curative medicine--Who uses what from when to when how?].

About the point of which medicine to use how in the medical treatment of osteoporosis, the large-scale clinical trial performed in Europe and America has been arranging. Especially, about calcium, vitamin D, estrogen, and bisphosphonates medicine can be used now based on the evidence about them. The necessity of medical treatment for the patient diagnosed as osteoporosis according to the criteria established by osteoporosis congress is guaranteed. However, when considering the necessity for prevention of osteoporosis, we would like to know the view about medicating osteopenia group, but there are few bases that for the moment it is important. Moreover, "up to when" in the point whether medical treatment is required, we have to wait for the report of the clinical test of medicine medication over a long period of time which is performed now. However, it is foundations to continue medicine medication as much as possible now, if effective. Although it became clear in estrogen medical treatment that a risk is higher than a benefit by medication examination over a long period of time, as well as this, It is necessary to discuss the benefit and the economic effect of an osteoporosis curative medicine.

Aged↗
PubMed2004

[Progress in quantitative ultrasound in measurement of bone quality].

The use of QUS (quantitative ultrasound) for the assessment of skeletal status has been continued and accelerating interest in recent years. The attractive of QUS lies in its low cost, portability, and freedom from ionizing radiation. These benefits, combined with clinical results showing good diagnostic sensitivity and the ability to predict fracture risk, have encouraged further basic investigation.

Bone Density↗
PubMed2003

[Prediction of fracture risk by QUS parameters].

It was reported that QUS may be set to predictor which evaluates the risk of fracture by large-scale epidemiology investigation conducted in Europe and America. All the prospective researches which computed relative risk of the fracture on elderly people who produced femur neck fracture beforehand, from the measured value of DXA and QUS. SOF and EPIDOS are the typical research. It was beforehand shown by any research that QUS predict fracture risk as well as DXA.

English Abstract↗
PubMed2002

Insufficient processing resources in Parkinson's disease: evaluation using multimodal event-related potentials paradigm.

The purpose of our study was to demonstrate impaired allocation of processing resources in non-demented patients with early-stage mild Parkinson's disease (PD) using a multimodal event-related potential (ERP) paradigm. The multimodal ERP paradigm was performed in 18 non-demented medicated patients with early-stage PD (Mini-Mental State Examination Score >26) and 16 matched normal controls, the Global Field Power (GFP) was employed for ERP components analysis, and the new modified Wisconsin Card Sorting Test (WCST) was used to evaluate frontal lobe function. Patients with PD did not exhibit novelty P3s, and P3 latency to non-target novel stimuli in visual and auditory modalities was significantly longer in PD patients than in controls. P3 amplitude for the target stimuli (P3b) was higher in PD in both auditory and visual modalities; however, P3b latency was not different between the two groups. Patients with PD showed a significantly lower score of achieved categories and made more perseverative errors in WCST as compared to controls. Our results showed that there were no natural novelty P3s in patients with PD; this finding suggests that non-demented patients with mild PD do not have sufficient mental resources to allocate to the central executive, due to dysfunction of the frontal lobe.

Acoustic Stimulation↗
PubMed2002

[Photodensitometry].

Explore the source record for details and available documents.

Absorptiometry, Photon↗
PubMed2002

[Nacrolepsy manifesting initially as cataplexy and sleep paralysis: usefulness of CSF hypocretin-1 examination for early diagnosis].

We report a 24-year-old man with narcolepsy initially suffered from cataplexy and sleep paralysis. From May 2000, at age 23 he experienced two kinds of recurrent episodes of weakness without altered consciousness; one was provoked by emotion and excitement, the other occurred spontaneously on onset of sleep without hallucination. He denied having daytime sleepiness and did not experience hypnagogic hallucinations. In July 2000, at our hospital he received the first medical examinations, of which physical and neurological results were unremarkable. A magnetic resonance imaging scan of the brain also gave unremarkable results. The initial diagnosis was epilepsy, and anti-convulsant drugs were begun in August 2000. The weakness episodes were not lessened by the treatment with carbamazepine, sodium valproate or clonazepam, and he was admitted to our clinic in April 2001 for further examinations. Human leukocyte antigen testing was positive for DR15 (DR2) and DQ6 (DQ1). The routine electroencephalographam detected no epileptic discharge or paradoxical alpha blocking. A polysomnogram showed a sleep onset REM sleep period and sleep fragmentation, but there was no apnea or periodic leg movements. A multiple sleep latency test showed a mean sleep latency of 1.8 min and REM sleep in three of five naps. These findings suggested probable narcolepsy, so we examined the hypocretin-1 (orexin A) concentration in his cerebrospinal fluid (CSF). It was below the detection limit of the assay (< 40 pg/mL). The final diagnosis in April 2001 was narcolepsy. Making an initial diagnosis of incomplete or atypical narcolepsy is difficult for clinicians. A delay in diagnosis, however, may produce personal and social problems for narcoleptic patients. We believe that an examination of CSF hypocretin-1 aids in the early diagnosis of narcolepsy.

Adult↗