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Biomedical subjects

K Amakawa

Publications and source records attributed to K Amakawa.

9 recordsLinked to original sources
PubMed1995

[The histological changes in the spinal cord following percutaneous cervical cordotomy (PCC) and correlation of these changes with the efficacy of PCC].

We observed the histological changes in the spinal cord following percutaneous cervical cordotomy (PCC) and correlation of these changes with the efficacy of PCC in 7 cases. A fine monopolar electrode which we used, measured 0.25 mm or 0.27 mm in diameter with exposed length of 2 mm. An oval or elliptical-shaped lesion, 1 to 3 mm in width and 3 to 4 mm in length, was observed in 6 of these cases. The main lesion was found in the anterolateral column in 5 cases. In 3 of these 5 cases, the whole anterolateral column had been destroyed, and in the other 2 cases dorsal one half to two thirds of it had been destroyed. In these 5 cases, pain sensation on the opposite side of PCC was lost for a long time and pain was relieved until death (21-239 days after PCC). In the other 2 cases the lesion in the anterolateral column was tenuous or unrecognizable, and the loss of pain sensation was temporary with pain recurring by the next day. This study showed that an oval or elliptical-shaped lesion was made in PCC and that in cases in which main lesion was located in the anterolateral column, pain relief was long lasting.

Adult↗
PubMed1995

[The efficacy of intravenous lidocaine on various types of neuropathic pain].

We examined the efficacy of systemic local anesthetics on various types of neuropathic pain in 89 patients. Lidocaine 1.5 mg.kg-1 was infused intravenously for one minute. Pain score (PS) by visual analogue scale (VAS, 0-10) was measured 1, 5, 15 and 35 min after the infusion. The efficacy of intravenous lidocaine was evaluated by PS which was lowest after infusion. PS decreased to less than 50 percent of pre-infusion value in more than 75 percent of cases of cancer pain, postherpetic neuralgia, trigeminal neuralgia, low back pain with signs of root pain or spinal canal stenosis, peripheral nerve injury and thalamic pain, in 50-75 percent of cases of herpetic neuralgia, and in less than 50 percent of cases of cervical spondylosis, spinal cord injury, reflex sympathetic dystrophy, causalgia and psychogenic pain. This study suggests that systemic local anesthetics is effective in neuropathy due to cancer pain, postherpetic neuralgia, trigeminal neuralgia, low back pain with signs of root pain or spinal canal stenosis, peripheral nerve injury and thalamic pain.

Aged↗
PubMed1994

[Classification of post-cordotomy dysesthesia].

Postcordotomy dysesthesia was classified from the clinical features of dysesthesia following percutaneous cervical cordotomy (PCC) in 66 patients. Dysesthesia occurred in 10 (15.2%) of 66 patients and was classified into three types. In the first type, dysesthesia occurred at the region where pain had been before PCC, and pain sensitivity had been lost due to PCC. This type of dysesthesia occurred in 6 patients. In this type, the peripheral nerve damage caused by tumor invasion was presumably the cause of dysesthesia. In the second type, dysesthesia occurred all over the region where pain sensitivity had been lost due to PCC. This type of dysesthesia occurred in 2 patients. The destruction of second order neurons of the nociceptive pathway by PCC was presumably the cause of this type of dysesthesia. In the third type, dysesthesia occurred at the region where pain had been before PCC and pain sensitivity had partially recovered. This type of dysesthesia occurred in 3 patients. The reduction of the effect of PCC was presumably the cause of this type of dysesthesia.

Adolescent↗
PubMed1992

Dynamic aspects of AMPs in the kidney in physiological conditions--their metabolism and turnover.

The past few decades have witnessed a number of studies on AMPs in the kidney. Almost all of these studies, however, have dealt with the quantitative and qualitative analysis of AMPs in the kidney using biochemical techniques, whereas the dynamic aspect of AMPs in the kidney has been overlooked and its metabolism and turnover have never been emphasized. On the other hand, the kidneys removed from humans and experimental animals revealed a wide variety in interstitial tissue in the medulla microscopically and in the papilla of the kidney macroscopically. The reasons for these variations in the medulla, its mechanism and the matrical component have not yet been clarified. In an effort to clarify these points, we herein describe our study on the dynamic aspect of AMPs in kidney histologically in relation to their biological turnover which we employed several staining methods. Our results revealed that there was a very active turnover of AMPs present in the kidney confirming that the kidney plays an important role physiologically in AMP metabolism. The degree of the turnover of AMPs in the kidney varies from case to case. In the active phase, AMPs are excreted in the glomerulus and reabsorbed in the proximal portion of the collecting tubules. Most of the absorbed AMPs are finally drained through the lymphatic vessels in situ and a few are excreted into the urine. Contrary cases have been demonstrated, however, only were a few AMPs were noted throughout the nephrons in the kidney. AMP turnover in the kidney is unexpectedly remarkable. The medulla, which has been considered less important, in fact, plays a key role in AMP metabolism.

Alcian Blue↗
PubMed1992

[Optimal pH and PaCO2 during moderate hypothermia].

Effects of pH and PaCO2 on cerebral as well as systemic hemodynamics and oxygen consumption were investigated during moderate hypothermia under 0.5% halothane anesthesia. Twenty-seven adult mongrel dogs were cooled to 28 degrees C (brain temperature) with a surface cooling method. They were divided into 3 groups, pH-stat (pH 7.35 n = 9), alpha-stat (pH 7.48 n = 9), and alkalosis (pH 7.70 n = 9). During hypothermia cardiac index fell to 74%, 56%, and 45%, and cerebral blood flow to 54%, 42%, and 36% in pH-stat, alpha-stat and alkalosis groups, respectively. Cerebral and systemic oxygen consumptions decreased to approximately 54% and 47%, respectively in all groups. Cerebrospinal fluid pH rose from 7.36 precooling to 7.49 (pH-stat), 7.53 (alpha-stat), and 7.72 (alkalosis). We concluded from these results that pH-stat and alpha-stat management have no significant effect on either hemodynamics or metabolism during moderate hypothermia but alkalosis management has deleterious effects because of the alkalinity itself and of the hyperventilation by which the alkalosis is induced.

Animals↗
PubMed1985

Responsiveness of cerebral vessels to changes of blood pressure and partial pressure of carbon dioxide after a transient period of cardiac arrest in dogs.

Post-ischemic cerebral hypoperfusion supposedly due to constriction of cerebral vessels is considered to be one of the most important factors limiting the recovery of the brain after cerebral ischemia. An experimental study on dogs was carried out to determine the changes in the responsiveness of cerebral vessel to the dilating effects of increase of arterial pressure (AP) and of CO2 inhalation after 3-6 min of cardiac arrest. Responsiveness was measured by the ratio of change in intracranial pressure (ICP) to change in AP (delta ICP/delta AP) and to change in PCO2 (delta ICP/delta PCO2), since in a bony cranium the changes in cerebral vessel diameter are reflected by instantaneous ICP change. delta ICP/delta AP following the administration of intravenous epinephrine was 33%, 43%, 36%, 37% and 16% of pre-ischemic value 1 h, 2 h, 3 h, 4 h and 5 h after cerebral ischemia, respectively. delta ICP/delta PCO2 following 10% CO2 inhalation was 13%, 32%, 55%, 50%, 70% and 75% of pre-ischemic value 1/2 h, 1 h, 2 h, 3 h, 4 h and 5 h after cerebral ischemia, respectively. Normal delta ICP/central venous pressure (delta CVP) was observed during the post-ischemic period, although statistical analysis was not done. From this we concluded: After 3-6 min of cardiac arrest, cerebral arteries constricted for more than 5 h during post-ischemic period. These arteries did not respond well to the dilating effects of increased arterial pressure or CO2 inhalation, but after 3 h their responses to CO2 inhalation returned to their pre-ischemic levels. The intracranial pressure became more or less dependent on CVP during post-ischemic period.

Animals↗