Biomedical subjects

H Hashizume

Publications and source records attributed to H Hashizume.

188 records · Page 11Linked to original sources

PubMedDate not supplied

Rapid changes in myofibrillar proteins after reperfusion of ischemic myocardium in dogs.

The effect of reperfusion on cardiac myofibrillar proteins in the irreversibly injured ischemic myocardium was studied in dogs. Ischemia of the myocardium was produced by complete occlusion of the left anterior descending coronary artery for 90 min (the group of 90I). Occlusion of the coronary artery was then released (reperfusion) for 0.5 min (the group of 90I + 0.5R), 5 min (the group of 90I + 5R), or 20 min (the group of 90I + 20R). In control dogs, the coronary artery was not occluded (the group of no ischemia). Myofibrils (Mfp) were prepared from the myocardium (with centrifugation) in each of the groups, and subjected to electrophoretic analysis in terms of myofibrillar proteins. The yield of Mfs in the groups of 90I, 90I + 0.5R, 90I + 5R, and 90I + 20R was lower than that in the group of no ischemia. There were no marked differences, however, in the electrophoretic pattern of Mfp among the five groups. These results suggest that myofibrils are broken down during reperfusion after ischemia. Therefore, supernatant solution after the first stage of homogenization during the course of preparation of myofibrils (mfs) was also examined. There were many unidentified bands in Mfs, being assumed to be originated from myofibrillar proteins, in the groups of both 90I + 0.5R and 90I + 5R, although these bands were not observed in the group of 90I. These results indicate that degradation of myofibrillar proteins occurs rapidly after reperfusion of the irreversibly injured myocardium. It is uncertain, however, whether reperfusion has a detrimental effect on the reversibly injured myocardium, too.

Actinin↗

PubMedDate not supplied

Histologic and scanning electron microscopic study of the glenoid labrum.

Three-dimensional fibrillar architecture of the glenoid labrum and its attachment to the glenoid rim were studied in 15 cadaveric shoulders to understand the pathophysiologic condition of various shoulder diseases. The true anatomic labrum was a narrow band located at the junction of the glenoid rim and fibrous capsule and varied considerably in size and shape. A triple-layered collagen structure of the labrum was observed by scanning electron microscopy. The thin superficial layer (articular surface) was a reticulated fibrillar network. The second layer was stratified. These two layers seem to act as a bumper against impact on the humeral head. The third, main layer of the labrum consisted of bundles of the fine fibrils densely arranged almost parallel to each other and oblique to the glenoid rim. This layer appears to act as a cushion to stabilize the shoulder joint.

Adult↗

PubMedDate not supplied

Anatomic relation between the medial collateral ligament of the elbow and the humero-ulnar joint axis.

The anatomic relation between the proximal attachment of the medial collateral ligament of the elbow joint and the humero-ulnar joint axis has not been clearly shown in a published study. We examined cadaveric specimens to find the exact relation between them. The medial collateral ligament was microscopically dissected to isolate specific fiber bundles. The length of each bundle was measured with a charge-coupled device camera system that faced the medial side of the elbow joint. The measurements indicated that the projected length of the deep middle bundle of the anterior oblique ligament, which is the strong cord-like part of the medial collateral ligament, is isometric during elbow flexion. The proximal end of the deep middle bundle was thus considered to be located almost on the humero-ulnar joint axis.

Cadaver↗

PubMedDate not supplied

Anatomic and histologic studies of lateral collateral ligament complex of the elbow joint.

We studied the gross and histologic anatomic characteristics of the lateral collateral ligament complex of the elbow joint from 15 cadavers to demonstrate its cross-sectional anatomy. The lateral ulnar collateral ligament adheres closely to the supinator, the extensor muscles, its intermuscular fascia, and the anconeus muscle and lies posterior to the radial collateral ligament. The lateral ulnar collateral ligament itself was identified with microscopy as a slender, poor structure consisting of the thick area of the posterolateral capsuloligamentous layer and a poorer structure than the anterior bundle of the medial collateral ligament as the primary stabilizer of the elbow joint. We believe that the lateral ulnar collateral ligament contributes to rather than is a major constraint to the posterolateral rotatory instability as part of the lateral collateral ligament complex with the surrounding tissues.

Aged↗

PubMedDate not supplied

Internal fixation for coronal shear fracture of the distal end of the humerus by the anterolateral approach.

Six patients with a displaced coronal shear fracture of the distal end of the humerus were treated surgically with the anterolateral approach to the elbow, in which the capitulum and trochlea could be exposed widely. All underwent open reduction and internal fixation to reduce anatomically and mobilize the joint at an early stage. The mean duration of follow-up was 40 months (range, 24-54 months). All fractures healed with an acceptable functional result. In no case did we observe collapse of the capitulum or trochlea. We recommend open reduction by the anterolateral approach, which provides good exposure of the fracture sites and allows internal fixation to be accomplished with the use of Herbert screws, resulting in good fixation and compression of the bone fragments.

Accidental Falls↗

PubMedDate not supplied

Acute posterolateral rotatory subluxation of the elbow joint. A case report.

The elbow joint has become increasingly recognized as a very important joint for all sports activities. Players in some sports cannot compete at all with an unstable elbow due to ligament injuries. Thus, professional sports players and heavy laborers, as in our case, should find the excellent results of primary ligament repair preferable. This technique is less invasive than secondary ligament reconstruction and can result primarily in an accurate, stable elbow with full range of motion for mobilizing the joint and muscles at an early stage.

Collateral Ligaments↗

PubMedDate not supplied

Bopindolol and its metabolite 18-502 attenuate regional myocardial acidosis during partial occlusion of the coronary artery in dogs.

The effects of bopindolol (a new, nonselective beta-adrenoceptor antagonist) and its active metabolite, 18-502, on the regional myocardial pH during coronary occlusion were studied. Mongrel dogs were anesthetized with pentobarbital and the thorax was opened to expose the heart. The left anterior descending coronary artery (LAD) was incompletely (or partially) occluded so that the LAD flow could be reduced to about one third of the original flow. Regional myocardial pH of the LAD area was continuously measured by a tissue pH monitor. Drugs were injected intravenously 30 minutes after LAD partial occlusion. The myocardial pH in the LAD area decreased in response to LAD partial occlusion (from 7.3-7.4 to 6.72-6.92), and the low pH value was sustained for 60 minutes after LAD occlusion. Atenolol (1 mg/kg) decreased heart rate markedly and attenuated the regional myocardial acidosis induced by LAD partial occlusion. Bopindolol (1 mg/kg) decreased heart rate and 18-502 (0.5 mg/kg) decreased heart rate and blood pressure. Both drugs attenuated to a similar degree the decrease of regional myocardial pH induced by LAD occlusion. In the dog whose heart rate was maintained constant, however, bopindolol (1 mg/kg) did not attenuate the decrease of regional myocardial pH induced by LAD occlusion. These results suggest that both bopindolol and 18-502 attenuate the ischemia-induced regional acidosis of the myocardium as does atenolol, and, hence, have an anti-ischemic action. The beneficial action of bopindolol on ischemia-induced myocardial acidosis is possibly due to a decrease of heart rate, which corresponds to a saving of energy in the myocardial cells.

Acidosis↗

PubMedDate not supplied

Dilazep inhibits binding of batrachotoxin to sodium channels in canine sarcolemmal vesicles.

We studied the effect of dilazep on the binding of [3H]- batrachotoxinin A 20 alpha-benzoate ([3H]BTXB), which binds to and stabilizes the activated state of the Na+ channel, and compared it with that of lidocaine in canine cardiac sarcolemmal vesicles. Dilazep inhibited the specific [3H]BTXB binding in a dose-dependent manner with an IC50 value of 0.37 microM, while lidocaine inhibited it with an IC50 value of 92 microM. Scatchard analysis of [3H]BTXB binding demonstrated that both dilazep and lidocaine reduced the amax without a marked effect on the K(D). The inhibition of [3H]BTXB induced by dilazep was reversible. Both dilazep (4 microM) and lidocaine (100 microM) increased the dissociation rate constant of [3H]BTXB only in concentrations which are about a 10-fold greater than their IC50, indicating the low affinity of both drugs for the [3H]BTXB-bound Na+ channel. However, dilazep (0.5 microM) and lidocaine (100 microM) decreased significantly the association rate constant of the [3H]BTXB binding at concentrations near their IC50, indicating that the affinity of both drugs for the [3H]BTXB-unbound Na+ channel is relatively high. These results suggest that, in canine cardiac membrane vesicles, the effect of dilazep in inhibiting the binding of [3H]BTXB and stabilizing the Na+ channel is similar to that of lidocaine, but the potency of dilazep is greater than that of lidocaine.

Aconitine↗