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Biomedical subjects

T Yamamura

Publications and source records attributed to T Yamamura.

At least 433 records · Page 24Linked to original sources
PubMed1981

Availability of plasma pancreatic polypeptide measurement in diagnosis of chronic pancreatitis.

Plasma pancreatic polypeptide (PP), a newly recognized pancreatic hormone, was studied in healthy subjects and patients with chronic pancreatitis. After an oral load of 50 g of meat extract, the plasma concentration of PP showed a rapid fourfold rise at 20 min in healthy controls. In contrast, the plasma PP level rose only 1.8-fold in patients with chronic pancreatitis. This difference was statistically significant (P less than 0.05). The increase rate of the PP level during the test in each subject correlated significantly (P less than 0.01) with total amylase output and maximal amylase concentration measured by the pancreozymin-secretin test. Thus, it is suggested that the measurement of the plasma PP level may be a useful tool to diagnose chronic pancreatitis.

Adult↗
PubMed1981

Fast oscillatory EEG activity induced by analgesic concentrations of nitrous oxide in man.

EEGs during inhalation of analgesic concentrations of 30%, 50%, and 70% nitrous oxide in oxygen, in the absence of other medication were studied in man. Although nitrous oxide has been considered to produce no significant change in EEG activity, it was found to produce characteristic fast oscillatory activity (FOA) in a predictable fashion. FOA was associated with unconsciousness or unresponsiveness to stimuli and appeared predominantly in the frontal areas. Power spectrum analyses showed that the frequency of FOA was remarkably constant across subjects and across trials with a peak frequency of 34 Hz. Amplitude and quantity of FOA increased as the concentration of nitrous oxide increased approaching 100 microV and more than 90%, respectively, under 70% nitrous oxide. It took approximately 1 hour after cessation of nitrous oxide before EEGs had completely returned control pattern with little FOA in spite of expected rapid decrease of alveolar nitrous oxide concentration. FOA can serve as a clinical monitor of the effectiveness of nitrous oxide analgesia.

Adult↗
PubMed1980

Oscillatory potentials of the cat lateral geniculate nucleus induced by barbiturate.

1. An orderly sequence in which the spontaneous electrical activity of the lateral geniculate nucleus (LGN) changes to a rhythmic one after intravenous administration of thiopental was studied in cats. 2. The response of LGN to barbiturate differed greatly from those of other thalamic specific nuclei. After administration of barbiturate, there appeared in the LGN a series of oscillatory potentials (barbiturate oscillatory potentials; BO potentials), the frequency of which changed sequentially from an initial 40 HZ to 10, 10, 5, and finally, 2.5 HZ. 3. Frequency changes of BO potentials in the LGN were observed only when the retinas were intact. Following destruction of bilateral retinas, the LGN responded to barbiturate with spindle activity as did other thalamic nuclei. 4. Depth potential analysis of the LGN activities showed that the BO potentials were generated in layers A and A1. By contrast, the spindle activity was recorded mainly from layer B. 5. Simultaneous recordings from the LGN and the optic nerve indicated that the BO potentials in the LGN were driven by retinal afferent discharges.

Action Potentials↗
PubMed1980

Postinhibitory rebound facilitation of the extension reflex in the high spinal cat.

Neural mechanisms of the reflex rebound of the hindlimb were studied in the high spinalized cat. After the animal had recovered from spinal shock, a light touch-pressure on the foot pad elicited a rebound extension reflex of the ipsilateral hindlimb. Excitability changes in hindlimb motor nuclei during the rebound phenomenon were examined by recording test monosynaptic reflexes (MSR). During touch-pressure stimulation, flexors such as the biceps femoris and tibialis anterior were facilitated, while extensors such as the gastrocnemius and quadriceps femoris were inhibited. After cessation of a stimulus, extensor MSRs showed a rebound facilitation which lasted for a few seconds. The greater the preceding suppression of MSR, the greater the rebound facilitation. Membrane potential changes induced in extensor motoneurons by touch-pressure were investigated by intracellular recordings. In most of the motoneurons tested (21/24), a clear membrane hyperpolarization was observed during stimulation and was followed by a rebound firing on cesstion of stimulation. Possible mechanisms underlying the rebound extension reflex were discussed.

Animals↗
PubMed1980

The effect of collagenase on the formation of fibrous long spacing collagen aggregates.

In order to elucidate the close relationship between the formation of fibrous long spacing fibers (FLS) and collagenase activity, electron microscopic studies on the rat skin using tissue culture technique were performed. In culture of newborn rat skin, a large number of FLS was formed in the dermis in which activity of endogenous collagenase was markedly elevated. Ethylenediaminetetraacetic acid (EDTA) supplemented to the culture medium completely arrested the formation of the FLS; subsequent exposure to bacterial collagenase resulted in the appearance of FLS in the same fashion. In another set of experiments utilizing exogenous enzyme digestion with bacterial collagenase or chondroitinase ABC on skins of 1-day-old and 1-year-old rats, it was demonstrated that the FLS formed by incubation with bacterial collagenase were found only in the regions of the dermis where reticular fibers were identified by light microscopy. There was no effect of chondroitinase ABC on FLS formation. These studies indicate that the FLS are formed in the presence of elevated endogenous collagenase and might be derived from reticular fibers which are degraded by collagenase.

Aging↗
PubMed1979

Familial type I hyperlipoproteinemia caused by apolipoprotein C-II deficiency.

A study was made on the clinical and biochemical features of siblings of patients with hyperchylomicronemia and its inherited relationship. It was not a case of the classical type of familial LPL deficiency, but of familial apolipoprotein C-II deficiency. The first patient with apolipoprotein C-II deficiency was reported by Breckenridge et al. and our patients provide the basis for the second report of this new disease. Our observations in this study strongly suggest that familial apolipoprotein C-II deficiency is transmitted by an autosomal recessive mode of inheritance and heterozygotes of this disorder have no abnormalities of plasma lipid and lipoproteins in spite of the reduced plasma apolipoprotein C-II.

Adolescent↗