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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 487 records · Page 27Linked to original sources

[A case report of primary repair for thoracic and thoracoabdominal and iliac artery aneurysms associated with severe visceral artery occlusive diseases--a redo operation for thoracoabdominal aortic aneurysm after infrarenal abdominal aortic aneurysm repair].

Abdominal aortic aneurysms can now be successfully repaired with low mortality and few early complications. On the other hand, the cases that required operations for recurrent aneurysms have been increased during long term follow-up period. In such cases, there are many difficulties for operative procedures compared to their first operations and many risk factors. A case of successful operation for the thoracoabdominal aortic aneurysm associated with severe stenotic lesions of the visceral arteries and descending thoracic aneurysm and left common iliac artery aneurysm are reported. A 74-year-old man who underwent operation for infrarenal abdominal aortic aneurysm and left nephrectomy 7 years and 9 months ago at our institution developed an aneurysm just above the proximal anastomosis with severe stenotic lesions of the visceral arteries. At the same time, descending thoracic aortic aneurysm and left common iliac artery aneurysm were associated. And he had ischemic heart disease. Under selective perfusion of the visceral arteries, graft replacement of these aneurysms and reconstruction of superior mesenteric artery and right renal artery were done. The patient had good post operative course and started oral feeding at 3 post operation day. He returned to his occupation and is doing well with no trouble one and half year after operation.

Aged↗

Operative results of thoracoabdominal repair for chronic type B aortic dissection.

From January 1991 to May 1994, we have operated on 15 cases of Type B aortic dissection. In 10 of these patients, thoracoabdominal repair was performed. According to Crawford's classification, 2 patients fell into Type I, 6 patients into Type II, and 2 patients into Type III. The aneurysms were exposed through a left thoracotomy extending into the retroperitoneum with the hemidiaphragm divided circumferentially. The operations were performed under femoro-femoral partial cardiopulmonary bypass. In 6 of these cases selective perfusion of the visceral branches was used. The celiac axis was reconstructed in 10 patients, superior mesenteric artery in 9, right renal artery in 7, left renal artery in 6. Abdominal vessels were reconstructed by the "inclusion" technique described by Crawford in 2 patients, by "beveling" the distal prosthetic end in 6 and by the "interposition" technique in 4 patients. Vessels arising from the false lumen were reconstructed by the "interposition" technique. To prevent paraplegia, the evoked spinal cord potentials by direct stimulation of the cord (ESPs-dsc) were monitored perioperatively and the aneurysms were repaired sequentially in segments. In all patients except 2 with Crawford type III aneurysms, spinal cord ischemia was detected by ESPs-dsc. In 7 of these patients, 2 to 8 pairs of intercostal/lumbar arteries (I/L aa.) that arose from the "responsible" aortic segment were reconstructed. Reconstruction techniques included the "inclusion" technique in 2 patients, the "beveling" technique in 1, the "interposition" technique in 1 and the "on lay grafting" technique in 3 patients. One hospital death occurred in a patient who had chronic renal insufficiency and liver cirrhosis preoperatively. Spinal cord injury occurred in 5 patients, including 4 paraparesis and 1 delayed-onset paraplegia. In 2 of these patients, responsible I/L aa., were not reconstructed correctly despite ESPs changes, and injury might have been prevented if reconstruction of the "responsible" arteries had been performed. Thoracoabdominal repair for chronic Type B aortic dissection could be performed safely with an acceptable mortality rate. Spinal cord injury remains an unsolved problem.

Aortic Dissection↗

The reliability of evoked spinal cord potentials elicited by direct stimulation of the cord as a monitor of spinal cord ischemia during temporary occlusion of the thoracic aorta.

Paraplegia is a severe and disastrous complication of operations on the thoracic aorta. For preventing this complication, we employed evoked spinal cord potentials elicited by direct stimulation of the cord (ESPs-dsc) during operations on 83 patients with various aortic lesions (37 dissecting and 46 cases of nondissecting aneurysms, 35 descending and 48 thoracoabdominal aortic aneurysms). All of the patients had some form of circulatory adjunct during aortic cross-clamping. Of the 83 patients, three had "immediate" paraparesis and five had "immediate" paraplegia, whereas three other patients had "delayed" paraplegia. During operation, four types of ESPs-dsc response pattern were observed: (1) no change (n = 57), (2) change with return (n = 15), (3) change with inconsistent return (n = 6), (4) change without return (n = 5). "Delayed" paraplegia occurred in two patients with "no change" and "change with return" response (3%), "immediate" paralysis occurred in three and "delayed" paraplegia occurred in one of those with "change with inconsistent return" response (67%), and all of those with "change with inconsistent return" response (67%), and all of those with "change without return" response developed "immediate" paraplegia (100%). We conclude that intraoperative monitoring of spinal cord function utilizing ESPs-dsc is a good indicator of spinal cord ischemia and we can improve the outcome according to its changes.

Aorta, Thoracic↗

[Knee pain in the aged--pathomechanism, diagnosis, and treatment of osteoarthritis of the knee].

Osteoarthritis is the most common cause of knee pain in the aged. This disease is characterized by degenerative changes in the articular cartilage and subsequent new bone formation at the articular margins. The primary defect in hyaline cartilage is an alteration in the ratio of total glycosaminoglycans to that of the collagen fiber content in the matrix. The disease frequently is primary but various predisposing conditions are recognized. In early phase of this disease, the patient complains of pain, which appears with exercise but can be "walked off". The joint is often felt to creak and grate, and swells from time to time, especially after any unusual activity involving a flexed position. As the disease progresses, the patient finds increasing difficulty in the activities of daily life. It should be emphasized that, in the early phase, almost of all patients can be managed by conservative means such as weight loss, isometric quadriceps exercises, use of a walking stick and antiinflammatory analgesic drugs. The predominant indication for surgical treatment is persistent pain and serious disturbance of the activities of daily life against conservative treatment. High tibial osteotomy has proved to be useful in the medial osteoarthritic knees. However, the long-term follow-up studies conducted by the author have shown that effects of this procedure gradually deteriorate after 10 years. Clinical results of total prosthetic replacement of the knee joint have been well improved in this decade. Ten-year survivorship has recently been reported to be 95% or more. However, the most common problem is loosening of the component. Wear particles derived from the tibial plate made from ultra high molecular weight polyethylene have been noted as the primary cause of the loosening.

Aged↗

[A case report of correction for total anomalous pulmonary venous connection in adult--usefulness of the superior approach].

In the repair of total anomalous pulmonary venous connection (TAPVC), some reports suggest that atrial arrhythmia was occurred as a late post-operative complication when the extended incision over the both atria was made by lateral approach, while the posterior approach in adult case often is difficult to expose operative field. A 42-year-old female patient with supracardiac type of TAPVC, Darling Ia type, was successfully corrected using superior approach. During procedure, the excellent operative field was obtained and large size of anastomosis between the posterior wall of left atrium and the common pulmonary vein could be carried out without lifting up the apex of the heart or the extensive incision of the both atria. The post-operative angiogram revealed no stenosis or distortion at the anastomotic site. We reviewed the 17 adult cases of supracardiac type of TAPVC repair in Japan, however, the superior approach was not reported. Our experience would suggest the superior approach is useful in the adult patient to repair supracardiac type of TAPVC. In addition to surgical approach, the pitfall of the post-operative hemodynamic changes in adult case of TAPVC repair was discussed.

Adult↗

Activation of histamine H3 receptors inhibits carrier-mediated norepinephrine release in a human model of protracted myocardial ischemia.

During protracted myocardial ischemia, ATP depletion promotes Na+ accumulation in sympathetic terminals and prevents vesicular storage of norepinephrine (NE). This forces the reversal of the neuronal uptake1 transporter, and NE is massively released (carrier-mediated release). We had shown that histamine H3 receptors (H3Rs) modulate ischemic NE release in animals. We have now used a human model of protracted myocardial ischemia to investigate whether H3Rs may control carrier-mediated NE release. Surgical specimens of human atrium were incubated in anoxic conditions. NE release increased approximately 7-fold within 70 min of anoxia. This release was carrier mediated because it was Ca++ independent and inhibited by the uptake1 inhibitor desipramine. Furthermore, the Na+/H+ exchanger (NHE) inhibitors ethyl-isopropyl-amiloride and HOE 642, and the Na+ channel blocker tetrodotoxin inhibited NE release, whereas the Na+ channel activator aconitine potentiated it. The selective H3R agonist imetit decreased NE release, an effect that was blocked by each of the H3R antagonists thioperamide and clobenpropit. Notably, imetit acted synergistically with ethyl-isopropyl-amiloride, HOE 642 and tetrodotoxin to reduce anoxic NE release. Thus, activation of H3R appears to result in an inhibition of both NHE- and voltage-dependent Na+ channels. Most importantly, endogenous histamine was released from the anoxic human heart, and thioperamide and clobenpropit each alone increased NE release, indicating that H3R become activated in myocardial ischemia. Our findings indicate that H3Rs are likely to mitigate sympathetic overactivity in the ischemic human heart and suggest new therapeutic strategies to alleviate dysfunctions associated with myocardial ischemia.

Aged↗

[Surgical results of postinfarction ventricular septal perforation: operative planning using "endocardial patch repair with infarct exclusion"].

Between 1983 and 1996, twenty-two consecutive patients underwent surgical repair for postinfarction ventricular perforation (VSP). Overall hospital mortality was 31.8% in the reviewed group. 15 patients were operated upon within two weeks of onset of VSP and hospital mortality was 27.3% in this group. The earlier operation might provide more favorable results in the surgery of VSP. When the preoperative coronary angiography revealed multivessel disease, concomitant myocardial revascularization was performed. In recent 2 cases, we employed the new technique introduced by Komeda and David for the reconstruction of the left ventricule using a single pericardial patch. We found this new technique had many advantages over traditional "Daggett's method". Better operative results could be expected with this technique.

Aged↗

Mycotic aneurysm of the bilateral tibioperoneal trunks associated with bacterial endocarditis: a case report.

Since antibiotics have been widely used in the treatment of bacterial endocarditis, mycotic aneurysms caused by septic emboli have become extremely rare. We report the case of a 34-year-old man who had mycotic aneurysms in the tibioperoneal trunks of both legs six weeks after he had a mitral valve replacement due to Streptococcus viridans endocarditis. Color Doppler sonography was used to diagnose pseudoaneurysms in both legs. Surgical treatment included the closures of the orifices of both aneurysms in both legs and arterial reconstructions were not required. In the literature, however, the location of mycotic aneurysms in peripheral arteries related to endocarditis were usually reported to be in the upper extremities or femoral arteries. Thus, we present the extremely rare case of mycotic aneurysms because the aneurysms occurred in the infrapopliteal vessel and developed in both legs.

Adult↗

[Effects of thiopental and sevoflurane on hemodynamics during anesthetic management of electroconvulsive therapy].

The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.

Adult↗

Analysis of the pancreatic beta cell in the mouse with targeted disruption of the pancreatic beta cell-specific glucokinase gene.

This is the first systematic study on the pancreatic beta cell function in the heterozygous mouse with targeted disruption of the beta cell glucokinase gene. The heterozygotes' beta cell displayed the following characteristics: (1) impaired glucose sensitivity with normal glucose responsiveness, (2) poor discrimination of alpha and beta glucose anomers, and (3) normal response to glucose in the presence of 25 mM K+ and 150 microM diazoxide. Both the first and the second phases of glucose-stimulated insulin release were depressed. Although the heterozygotes were mildly hyperglycemic, insulin treatment further suppressed beta cell function, implying the beta cell glucose toxicity is not the cause of impaired glucose sensitivity. The data are compatible with the glucokinase glucose sensor concept inasmuch as glucose sensitivity is reduced in the heterozygotes' beta cell. The anomeric malaise and preservation of the ATP-sensitive K+ channel-independent glucose action were considered due to chronic hyperglycemia.

Animals↗

Central distribution and peripheral functional properties of afferent and efferent components of the superior laryngeal nerve: morphological and electrophysiological studies in the rat.

The central distribution of the afferent and efferent components of the superior laryngeal nerve (SLN), which in the rat is ramified into the three branches of the rostral branch (R.Br), middle branch (M.Br), and caudal branch (C.Br), was examined after application of horseradish peroxidase conjugated with wheat germ agglutinin (HRP-WGA) to the proximal cut end of each branch. In addition, the afferent and efferent neural activities of each branch were recorded to investigate the functional properties. The present study provided several new findings as to the distribution of each branch and the functional properties of the SLN. The following conclusions were drawn: 1) the R.Br, containing only afferent fibers projecting to the ipsilateral lateral region of the nucleus of the solitary tract (NST), extends between slightly below the obex and the region approximately 0.6 mm rostral from the obex, and it corresponds to the interstitial subnucleus of the NST; 2) the M.Br, innervating the cricothyroid muscle, contains only efferent fibers originating ipsilaterally from the motoneurons localized within the ambiguus nucleus (Amb) and in the area ventrolateral to the Amb; and 3) the C.Br, which innervates the inferior pharyngeal constrictor muscle, contains both efferent and afferent fibers. HRP-WGA-labeled cells are distributed within both the Amb and the dorsal motor nucleus of the vagus nerve, ipsilateral to the injection site. Afferent proprioceptive fibers project to the ipsilateral interstitial subnucleus of the NST. The present results provide evidence that each branch of the SLN has distinctive functional properties and contributes to the laryngeal functions.

Afferent Pathways↗

Electron microscopic observation of synaptic connections of jaw-muscle spindle and periodontal afferent terminals in the trigeminal motor and supratrigeminal nuclei in the cat.

Previous studies indicate that the trigeminal motor nucleus (Vmo) and supratrigeminal nucleus (Vsup) receive direct projections from muscle spindle (MS) and periodontal ligament (PL) afferents. The aim of the present study is to examine the ultrastructural characteristics of the two kinds of afferent in both nuclei using the intracellular horseradish peroxidase (HRP) injection technique in the cat. Our observations are based on complete or near-complete reconstructions of 288 MS (six fibers) and 69 PL (eight fibers) afferent boutons in Vmo, and of 93 MS (four fibers) and 188 PL (four fibers) afferent boutons in Vsup. All the labeled boutons contained spherical synaptic vesicles and were presynaptic to neuronal elements, and some were postsynaptic to axon terminals containing pleomorphic, synaptic vesicles (P-endings). In Vmo neuropil, MS afferent boutons were distributed widely from soma to distal dendrites, but PL afferent boutons predominated on distal dendrites. Most MS afferent boutons (87%) formed synaptic specialization(s) with one postsynaptic target while some (13%) contacting two or three dendritic profiles; PL afferents had a higher number of boutons (43%) contacting two or more dendritic profiles. A small but significant number of MS afferent boutons (12%) received contacts from P-endings, but PL afferent boutons (36%) received three times as many contacts from P-endings as MS afferents. In Vsup neuropil, most MS (72%) and PL (87%) afferent boutons formed two contacts presynaptic to one dendrite and postsynaptic to one P-ending, and their participation in synaptic triads was much more frequent than in Vmo neuropil. The present study indicates that MS and PL afferent terminals have a distinct characteristic in synaptic arrangements in Vmo and Vsup and provides evidence that the synaptic organization of primary afferents differs between the neuropils containing motoneurons and their interneurons.

Animals↗

Light microscopic observations of the contacts made between two spindle afferent types and alpha-motoneurons in the cat trigeminal motor nucleus.

Previous studies indicate that cat jaw-muscle spindle afferents can be divided into two types (type I and II) on the basis of their axonal trajectories. The present study examined the relationship between spindle afferent fibers and their target masseter alpha-motoneurons in the cat by using the intracellular horseradish peroxidase (HRP) injection technique, and provided several new findings on the synaptic organization generated between the two. Five type I afferent fiber-motoneuron pairs and nine type II afferent-motoneuron pairs were well stained with HRP. The following conclusions were drawn: 1) A motoneuron received contacts from only one collateral of any given spindle afferent. 2) The number of contacts made between an afferent and a motoneuron ranged from one to three. 3) The contacts made by a spindle afferent were on the same dendrite or dendrites branching from the same primary dendrite. 4) The vast majority of the contacts made by an afferent on a motoneuron were distributed in the dendritic tree within 600 microns from the soma, i.e., in the proximal three fourths of the dendritic tree. The differences observed between the two afferent types were as follows. First, type II afferent terminals made contacts on more distal dendrites of the motoneurons than did type I afferent terminals. Second, the contacts made between a type I afferent and a motoneuron were clustered together, but those made between a type II afferent and a motoneuron were widely dispersed. The present results provided the general rules of synaptic contacts between the spindle afferents and masseter alpha-motoneurons, and demonstrated that the spatial distribution of synaptic contacts on the dendritic tree was different between type I and type II afferents.

Animals↗

Micturitional disturbance and the pontine tegmental lesion: urodynamic and MRI analyses of vascular cases.

Micturitional histories were taken from 39 patients with acute brainstem stroke. Within 3 months from onset, 49% had irritative as well as obstructive urinary symptoms, the most common being voiding difficulty and nocturnal urinary frequency in 28%, followed by urinary retention in 21%. Urodynamic studies of 11 symptomatic patients revealed detrusor hyperreflexia in 73%, low compliance bladder in 9%, atonic cystometrogram in 27%, detrusor-sphincter dyssynergia in 45% and uninhibited sphincter relaxation in 27%. Three asymptomatic patients had normal urodynamic findings. Brain magnetic resonance images of the lesions of the symptomatic patients were concentrated in the dorsolateral pons including pontine reticular nucleus and the reticular formation adjacent to the medial parabrachial nucleus and the locus coeruleus. These regions seem to be mainly responsible for supranuclear types of pelvic and pudendal nerve dysfunction in our patients with brainstem stroke, corresponding to the pontine urinary storage and micturation center reported in animal studies.

Adult↗