Hideo Matsuura

Change in tracheal blood flow during endotracheal intubation

Changes in blood flow in the tracheal mucosa of the dog caused by the pressure exerted by high‐volume, low‐pressure cuffs were measured with the hydrogen clearance method. Before inflating the cuffs, the blood flow of the tracheal mucosa was measured as a control for 12 h in order to confirm that the procedures of the hydrogen clearance method itself had little or no influence on the blood flow in the tracheal mucosa. After inflating the cuffs to create a tracheal wall pressure (TWP) of 1.3 kPa (10 mmHg), 2.6 kPa (20 mmHg), 3.9 kPa (30 mmHg) or 6.0 kPa (45 mmHg), local blood flows of tracheal mucosa (TBF) corresponding to each TWP were measured every hour for 12 h. No significant changes in blood flow were observed in the tracheal mucosa with the hydrogen clearance method before inflating the cuffs. In the groups with TWP of 1.3 and 2.6 kPa, the TBF rose 1 h after inflation of the cuffs, and then returned to the baseline values. In the group with TWP of 6.0 kPa, the TBF decreased markedly already 1 h after inflation of the cuffs, and continued to decrease severely thereafter. In the group with TWP of 3.9 kPa, the TBF followed an intermediate course between the groups with TWP of 2.6 kPa and 6.0 kPa. From the results of the present study, it was found that TBF was significantly impaired by a TWP of more than 3.9 kPa. Therefore, in prolonged intubation, TWP should be kept at or below 2.6 kPd.

Influence of electro-acupuncture on the release of substance P and the potential evoked by tooth pulp stimulation in the trigeminal nucleus caudalis of the rabbit

The effects of electro-acupuncture (EAP) on the release of substance P (SP) and the responses evoked by tooth pulp stimulation (ST) in superficial layers of the trigeminal nucleus caudalis (Vc-I,II) were studied in rabbits. ST evoked increase in release of immunoreactive SP (iSP). This increase was inhibited by EAP in 9 of 13 animals. The potentials evoked by ST were composed of two main components with latency times of ca 4.3 msec and ca. 9.4 msec. The latter component, reflecting the excitation of A delta fibers, was significantly inhibited by CP-96,345 (3 mg/kg, i.v.), an SP antagonist. EAP also inhibited the latter component in 8 of 11 animals. These results suggest that one of the mechanisms of analgesia induced by EAP is inhibition of stimulus-evoked SP release in the Vc-I,II.

Safety of dental treatment in patients with previously diagnosed acute myocardial infarction or unstable angina pectoris

OBJECTIVE The purpose of this study was to assess the safety of invasive dental treatments, such as tooth extraction and pulpectomy under local anesthesia, in patients with unstable angina pectoris and within 6 months after onset in patients who had experienced acute myocardial infarction. STUDY DESIGN Cardiovascular complications during and after dental treatment and preoperative risk factors were explored in 63 patients who had experienced unstable angina pectoris or acute myocardial infarction. RESULTS A total of 79 dental treatments were performed with no intraoperative complications. Chest pain occurred in 8 patients within 1 week after dental treatment. Risk factors for postoperative complications were identified as a history of chest pain within 2 weeks before the dental treatment and failure to clear the Master Test Single stress test. CONCLUSIONS Many patients who had experienced unstable angina pectoris or acute myocardial infarction tolerated dental treatment when appropriate stress control measures were used. However, approximately 10% of the patients experienced postoperative problems. Acceptability of dental treatment should be determined on the basis of the comprehensive assessment of each patient.

Effect of ethanol on hippocampal GABA receptors in the rat brain

The effect of ethanol on GABA receptors was studied in hippocampal slices and membrane preparations of the rat brain. In slice preparation, ethanol enhanced the GABA inhibition of the population spikes evoked in CA 1 pyramidal cells by Schaffer collateral stimulation. The effect of ethanol was dose-dependent being observed with minimal concentration of 70 mM. In 3H-GABA binding experiments, ethanol enhanced the binding to fresh membranes with no change in the affinity. Maximal stimulation was observed at ethanol concentration of 70 mM. In hippocampal slices or membrane preparations obtained from ethanol- or barbital-administered rats chronically, ethanol failed to enhance GABA function. Thus, the present study demonstrated the involvement of GABA in central effect of ethanol. Also suggested in GABA was the involvement in the development of cross-tolerance between ethanol and barbiturates.

A histochemical and electron-microscopic study of the trigeminal ganglion of the rat.

Abstract The electron-microscopic and the enzyme histochemical studies were carried out and the following findings obtained: 1. (1) Light-microscopically, three types of the nerve cells were distinguished, i.e., large cells, small cells and intermediate cells. Electron-microscopically, three types of cells were also discernible, i.e., clear cells, dark cells and transitional cells. The diameter of large cells was about 60 μ and that of dark cells, 30 μ. The mitochondrial dehydrogenases were more evident in the nerve cell bodies than in capsular cells. Mitochondria were more numerous in nerve cell bodies than in capsular cells. In dark cells, the mitochondrial dehydrogenases were concentrated in the perinuclear area and AChE was mainly localized in the peripheral portion of the perikaryon. In large cells, these enzymes were distributed throughout the perikaryon. The intracellular localization of the enzymes were coincident with the intracellular distributions of the mitochondria and the rough surfaced endoplasmic reticulum in the perikaryon of the aforementioned nerve cell types. Therefore, it was suggested that the large cell was identical with the clear cell, the small cell with the dark cell and the intermediate cell with the transitional cell. 2. (2) The capsular and/or the Schwann cell intervened between the neuron and capillary vessels. 3. (3) The capsular cell showed the characteristically prominent stainability to NADP-dependent IDH, G6PDH and to ALP. Electron-microscopically, the two types of the capsular cells were discernible, i.e., dark capsular cells and clear capsular cells. At the junction of clear cells and capsular cells there were “labyrinthine structures” and “trophospongium” and these structures may play a role in the transportation of nutrition between the two cells. On the other hand, no such structure was observed in dark cells. 4. (4) It is reasonable to assume that there is transformation of the nerve cell types in various biological states from dark cell to clear cell.

Electron microscopic localization of alkaline phosphatase in the trigeminal ganglion of the rat.

SummaryThe electron microscopic demonstration of alkaline phosphatase (ALP) was carried out on the trigeminal ganglion of the rat using the calcium lead modification method by Gomori (Gomori, 1952; Molnar, 1952).The ALP reaction was localized on the junction of capsular cells and nerve cells, in the cytoplasm of some dark capsular cell and in that of the endothelial cell: The enzymatic reaction products (1) existed throughout the entire length of the junction of clear cells and capsular cells, (2) aggregated at some points of the junction of dark cells and capsular cells, (3) existed on the smooth and/or rough surfaced endoplasmic reticulum and on the ribosomes of some dark capsular cells.

Histochemical observation of bovine spinal ganglia.

SummaryMorphologically, large oval cells, small oval cells and intermediate cells were distinguished among the nerve cells of the bovine spinal ganglion. — The nerve cells generally showed the prominent enzymatic reactions to SDH, NAD-, NADP-dependent MDH, GDH and NAD-dependent IDH.— Large cells reacted somewhat slightly to alpha-GDH, G-6-PDH and NADP-dependent IDH, while intermediate and small cells reacted strongly. LDH reaction of large and small cells was moderate and that of intermediate cells varying. — In general, to the dehydrogenases tested, intermediate cells were most stainable and small cells reacted in the varying degrees. Considerable reactions for dehydrogenases were present in the capsular cells especially in the case of NADP-dependent IDH and G-6-PDH. The nerve fibers were less stainable to the dehydrogenases. MAO activity was observed in the capsular cells, nerve fibers and a large number of the nerve cells. — AChE reaction of the nerve cells was various and that of the capsular cells negligible, while ChE activity was limited to the capsular cells. ACP activity in nerve and capsular cells was positive, and ALP activity was confined to the capsular cells and the capillary vessels. Intense ATPase activity was localized in the capsular cells, peripheral zone of the neuroplasm and the neurilemma.

A report of 14,195 applications of anesthetics to oral and maxillofacial surgery at one teaching dental hospital (1971-2000) centering around airway problems.

STUDY OBJECTIVES To examine the validity of our methods of anesthesia, i.e., awake intubation and assisted manual ventilation, in coping with the anesthetic problems particular to oral and maxillofacial surgery (OMF surgery). DESIGN Prospective study. SETTING Operating room and ward of a dental teaching hospital. PATIENTS 14,195 patients undergoing OMF surgery during the period from January 1971 to March 2000. MEASUREMENTS AND MAIN RESULTS The kinds of anesthetic difficulties centering around airway problems and their frequency in OMF surgery were determined. In 2,401 patients (16.9%), awake intubation was employed because of definite or possible airway problems. No untoward effects due to awake intubation were noted. Volatile anesthetics were used with nitrous oxide (N2O) in 13,959 patients (98.3%), and their spontaneous respiration were assisted manually for the purpose of early detection of airway troubles such as accidental extubation, dislocation, kinking, and/or damage to the endotracheal tubes. Few accidents or complications were noted in relation to airway issues, and neither cardiac arrest nor death was experienced in these 14,195 patients. CONCLUSIONS Based on a sufficient number of anesthetic applications, awake intubation and assisted manual ventilation were proved to be useful in coping with the anesthetic difficulties particular to OMF surgery.

Effect of thiopental on hippocampal GABA receptors in rat brain

The effect of thiopental on rat brain hippocampal GABA receptors was studied in slice preparations and membrane fractions. In slice preparations, thiopental at a concentration of 10(?5) M enhanced the GABA (1?5 x 10(?4)M) inhibition of the field potentials evoked in pyramidal neurons by stratum radiatum stimulation. In hippocampal slices obtained from chronically barbital-administered (100 mg/kg, b.i.d., 10 days) rats, less enhancement of thiopental on GABA inhibition of the field potentials was observed. In binding experiments, two components of specific [(3)H]GABA binding to membrane fractions were observed. While thiopental was without effect on high-affinity sites, [(3)H]GABA binding with low affinity was enhanced by 80% in the presence of 10(?5) M thiopental. The results are discussed in relation to the phenomena underlying chronic barbiturate administration.

The ultrastructural localization of acetylcholinesterase in the trigeminal ganglion of the rat

SynopsisThe presence of acetylcholinesterase in the trigeminal ganglion of the rat has been investigated at the light and electron microscope levels using Karnovsky and Rootss method.The acetylcholinesterase reaction was mainly localized in the neuron. In the nerve cell body, the reaction was observed:(1)as small electron opaque dots corresponding to fixed or free ribosomes;(2)either on the membrane of or within the smooth-surfaced endoplasmic reticulum or both;(3)either on the membrane of or within the large vesicles or both;(4)in the ‘labyrinthine structure’ at the junction of the capsular cells and nerve cell bodies; and(5)on the nuclear envelope. In the nerve fibre, whether myelinated or unmyelinated, the acetylcholinesterase reaction was confined to the axolemma and to the neurotubules.