Prostacyclin analogue, beraprost, sustains recanalization duration after thrombolytic therapy in acute myocardial infarction model

Platelets play an important role in acute reocclusion after thrombolysis in acute myocardial infarction. We tested a new antiplatelet agent, the stable prostacyclin analogue, beraprost, in the prevention of reocclusion of reperfused vessels with a combination of recombinant tissue-type plasminogen activator (rt-PA) in a canine preparation of coronary artery thrombosis superimposed on high-grade stenosis. Intravenous infusion of rt-PA (17 micrograms/kg/min for 30 min) was combined with beraprost (100, 200 or 300 ng/kg/min for 60 min) or aspirin (35 mg/kg bolus i.v. before rt-PA infusion). The reperfusion time did not differ among the 4 groups. The time from reperfusion to reocclusion (one cycle) in the rt-PA plus beraprost 200 ng/kg/min group was significantly longer than the rt-PA alone group (40 +/- 8 min vs. 9 +/- 2 min, P < 0.05) and the recanalization duration calculated as the mean time from reperfusion to reocclusion in each cycle was prolonged in the rt-PA plus beraprost 200 ng/kg/min group compared with the rt-PA alone group (48 +/- 6 min vs 18 +/- 5 min, P < 0.05) and the reocclusion time and recanalisation duration tended to be elongated in the rt-PA plus beraprost 300 ng/kg/min group, whereas those were not altered by aspirin and 100 ng/kg/min of beraprost. Bleeding time was slightly prolonged and ex vivo platelet aggregation was slightly depressed by beraprost and aspirin. Systemic blood pressure was lowered with higher doses of beraprost. Beraprost sustained coronary reperfusion time and recanalization duration at the higher doses with an optimal level, but could not eliminate reocclusion completely.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcranial magnetic stimulation excites the root exit zone of the facial nerve

The actual site of excitation of the facial nerve by transcranial magnetic stimulation was investigated in five patients with hemifacial spasm who underwent microvascular decompression. The facial nerve was stimulated preoperatively and intraoperatively by transcranial magnetic stimulation and intraoperatively by electrical stimulation at its root exit zone with a minimum of surgical invasion of the facial nerves. The onset latency of compound muscle action potentials recorded from the nasalis muscle was 5.06 +/- 0.44 ms by magnetic stimulation and 5.08 +/- 0.43 ms by electrical stimulation. The latency difference was 0.06 +/- 0.08 ms. Therefore, transcranial magnetic stimulation was basically the same as electrical stimulation in onset latency. From this study, it appears that the root exit zone of the facial nerves is stimulated by transcranial magnetic stimulation.

Selective jugular cannulation of safer retrograde cerebral perfusion

Hypothermic retrograde cerebral perfusion is a new technique for protecting the brain. Satisfactory cerebral protection should be possible even for periods of retrograde perfusion greater than 60 minutes. However, there are some concerns that functioning venous valves at the jugular-subclavian junction may impede retrograde flow to the brain and consequently cerebral protection may not be adequate. To overcome this obstacle, we have developed an easy and safe technique of selective jugular cannulation through the right atrium using a central venous catheter and a guidewire. We have employed this technique successfully in 15 patients who underwent operation on the aortic arch.

Effects of beta 6 amino acid hydrophobicity on stability and solubility of hemoglobin tetramers

The relationship between different amino acids at the beta 6 position of hemoglobin and tetramer stability was addressed by a site-directed mutagenesis approach. Precipitation rates during mechanical agitation of oxyhemoglobins with Gln, Ala, Val, Leu and Trp at the beta 6 position increased 2, 5, 13, 21 and 53 times, respectively, compared with that for Hb A. There was a linear relationship between the log of the precipitation rate constant and amino acid hydrophobicity at the beta 6 position, suggesting that enhanced precipitation of oxy Hb S during mechanical agitation results in part from increased hydrophobicity of beta 6 Val. Deoxyhemoglobin solubility increased in the order of beta 6 Ile, Leu, Val, Trp, Gln, Ala and Glu suggesting that hydrophobic interactions between beta 6 Val and the acceptor site of another hemoglobin molecule during deoxy-Hb S polymerization not only depend on hydrophobicity but also on stereospecificity of the amino acid side chain at the beta 6 position. Furthermore, our results indicate that hydrophobic amino acids at the beta 6 position which promote tetramer instability in the oxy form do not necessarily promote polymerization in the deoxy form.

An in vitro study of magnetization transfer and relaxation rates of hematoma

PURPOSE

To assess, in an in vitro model of acute hematoma, whether hemoglobin immobilization by clot and red cell membrane aging can account for the T2 shortening usually attributed to deoxyhemoglobin.

METHODS

Clotted and heparinized blood samples were packed (100% hematocrit). The apparent magnetization transfer rate (AMTR), T1 and T2 relaxation rates of the samples, and images with a volunteer's head were obtained at 1.5 T.

RESULTS

The AMTR and T1 and T2 relaxation rates were unaffected by the presence of clot. The AMTR was unaffected by red cell aging. The diamagnetic packed blood samples, which are much denser than brain, were isointense to gray matter on T2-weighted images and had about one-fifth the AMTR of white matter.

CONCLUSIONS

Hemoglobin immobilization by clot structure or red cell contraction with aging is insignificant and does not contribute to the T2 shortening of acute hematoma. The low AMTR and T2 relaxation rates of diamagnetic blood appear to be caused by the mobility of hemoglobin and by the red cell's lack of immobile macromolecular structures such as those associated with nucleated brain cells.

Histochemical demonstration of NADPH-diaphorase activity, a marker for nitric oxide synthase, in neurons of the rat pancreas

To clarify the role of nitric oxide (NO) in the pancreas, we histochemically investigated NADPH-diaphorase, a marker for NO synthase, in the rat pancreas. NADPH-diaphorase activity was localized in the neurons and endothelium of vessels. The nerve fibers with NADPH-diaphorase activity were observed in both the exocrine and the endocrine pancreas associated chiefly with the vascular systems. Most nerve cell bodies (98.5%) within the pancreatic parenchyma showed strong activity for this enzyme. These results suggest that NO may participate in the hemodynamic control of the pancreas and in the neuronal regulation of pancreatic exocrine and endocrine functions.

Study of chronic schizophrenics using 31P magnetic resonance chemical shift imaging

Phosphorus-31 chemical shift imaging showed regional abnormalities of in vivo 31P NMR spectra in the brains of chronic schizophrenic patients. In the left temporal region, the level of % phosphodiesters (PDE) was increased and the level of % gamma alpha beta-ATP (obtained by summation of gamma-ATP, alpha-ATP, and beta-ATP) was decreased. In the basal ganglia, the levels of % PDE were decreased and the level of % phosphomonoesters was increased. The levels of % gamma alpha beta-ATP were increased in the right basal ganglia. The level of % phosphocreatine was decreased in the frontoparietal region. These findings may represent different patterns of dysfunction of membrane phospholipid bilayers and high-energy phosphate metabolism in the specific cerebral regions.

Traumatic internal carotid artery occlusion--case report

A 20-year-old male was admitted comatose immediately after a motorcycle accident. Initial computed tomography demonstrated traumatic subarachnoid hemorrhage, and the diagnosis of traumatic internal carotid artery occlusion was established by angiography. Conservative management improved his symptoms, but eventually he died from delayed traumatic apoplexy. Traumatic internal carotid artery occlusion is relatively rare, but is serious and requires early diagnosis and treatment. For patients with severe head trauma and vascular occlusion, anticoagulants are contraindicated, and frequent follow-up angiography is recommended.

[Coronary artery bypass surgery in the elderly]

In recent years it has become apparent that the number of persons 70 years of age or older is increasing. Between June, 1980, and December, 1990, 75 patients 70 years of age and older (range, 70-79 years; mean 73.1) underwent isolated coronary artery bypass grafting (CABG). During this same interval, 507 patients less than 70 years old underwent isolated CABG. Preoperative status in the elderly showed a significantly greater prevalence of women, urgent or emergent operation, triple vessel disease and diabetes. Operative mortality was higher among the elderly compared with the younger patients (p < 0.05). The increased frequency of urgent or emergent operation in the elderly was associated with postoperative complications. Major complications related CABG in the elderly were serious cerebrovascular accidents and low cardiac output syndrome. In order to improve the results of CABG in the elderly, it is essential to perform the elective operation following careful evaluation of both cardiac function and central nervous system.

12(R)-hydroxyeicosatetraenoic acid synthesis by 3-methylcholanthrene- and clofibrate-inducible cytochrome P450 in porcine ciliary epithelium

Porcine ciliary epithelial microsomes synthesized 12[S]-hydroxy-5, 8, 10, 14-eicosatetraenoic acid (12[S]-HETE) from arachidonic acid by a membrane-bound lipoxygenase and 12[R]-isomer by the cytochrome P450-dependent monooxygenase system. The activity to form 12(R)-isomer was markedly enhanced by 3-methylcholanthrene and clofibrate. Both basal and induced levels of 12(R)-HETE synthesizing activity were considerably higher in nonpigmented epithelial cells than in pigmented cells of the ciliary processes. The induced activity was suppressed by polyclonal antibodies raised against purified cytochrome P450 IA1 and NADPH-P450 reductase but not by substrates for clofibrate-inducible omega/omega-1 hydroxylases (P450 IVA-mediated). These results suggest that 12(R)-HETE synthesis by porcine ciliary microsomes may be mediated by a cytochrome P450 of the IA family.

Spatial and temporal analysis of solid-state imaging systems

Temporal and spatial properties of the image that is stored in the digital memory of a frame grabber through a solid-state image sensor, which employs the X-Y addressing method for scanning the image, are analyzed in the space-time domain by using the mathematical expression that we have obtained. This expression includes not only the static effects of the finite picture-cell size of the sensor and the image sampling in both the sensor and the grabber but also the dynamic effects of the temporal response of photoelectric conversion in the sensor, a one-dimensional electrical filter of the camera controller, and the asynchronous sampling with regard to time in both the sensor and the grabber. Results of the experiment and the numerical simulations based on the mathematical expression are presented for a time-varying one-dimensional object with good agreement.

Recurrent hemoptysis due to aortobronchopulmonary fistula of false aortic aneurysm associated with repair of rupture of the sinus of Valsalva

A 54-year-old man presented with recurrent hemoptysis of one year duration. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a saccular aneurysm of the ascending aorta. The aneurysm was intraoperatively found to have formed on the superior surface of the site of aortotomy suture placed during previous repair of rupture of the sinus of Valsalva and to have a fistulous communication to the lung. CT and MRI were very useful in the diagnosis of the aneurysm as the cause of hemoptysis.

Cytochrome P450-mediated prostaglandin omega/omega-1 hydroxylase activities in porcine ciliary body epithelial cells

The ocular hypotensive effect of topically applied prostaglandins (PGs) is well documented. Although PGs introduced in the posterior chamber accumulate in the anterior tissues (e.g. iris/ciliary complex), little is known about the metabolism of PGs by these tissues. We have recently found that non-pigmented epithelial (NPE) cells and pigmented epithelial (PE) cells are readily separated from porcine ciliary body and cytochrome P450-dependent xenobiotic metabolism is considerably higher in NPE cells than in PE cells. We have therefore investigated in this study the cytochrome P450-mediated PG omega/omega-1 hydroxylase activities of porcine ciliary epithelial cells. The NPE cells show about three times higher activities than do PE cells; the NPE cells, in fact, demonstrate the highest PG omega/omega-1 hydroxylase activities among different ocular tissues. Both omega and omega-1 hydroxylases show broad substrate specificities and hydroxylate PGA1, A2, E1, E2, and lauric acid. The omega/omega-1 hydroxylase activities of NPE and PE, as determined with PGA2 and lauric acid as substrates, are enhanced or induced by treatment of primary cultures of the individual epithelial cells with clofibrate, both activities reaching maximum levels within 48 hr of induction. The induced activities are inhibited almost completely by cycloheximide and actinomycin D. The omega/omega-1 hydroxylase activities of both NPE and PE cells require NADPH and molecular oxygen, are associated with the microsomal fraction, respond to inducers such as clofibrate, and are inhibited by metyrapone and SKF525 A (inhibitors of P450 enzymes). These results support the suggestion that PG omega/omega-1 hydroxylations by NPE and PE are cytochrome P450-mediated reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of local tumor removal and retained oncolysate on lung metastasis

We reported earlier that oncolysate retained in the excision wound of a local tumor inhibits growth of remote tumor in the rat. We further studied this effect on pulmonary metastasis. C57BL/6 mice were given B16 melanoma F10 cells subcutaneously into the gluteal area (Day 0) and then intravenously on Day 10. On Day 14, mice were divided into four groups. Group 1 received a sham operation and no further treatment. Tumors were excised in the remaining mice. Group 2 received tumor excision alone. Groups 3 and 4 received injections of freeze-lysed tumor cells (TC) and lysate modified (PTC) with a hapten, L-phenylalanine mustard (PhM), respectively, into excision wounds. On Day 24, metastases were assessed by determining metastatic burden. Average diameters of excised tumors in repeated experiments ranged from 8.7 to 10.9 mm. In repeat experiments, pulmonary metastatic burden increased by as much as 52 to 181% in the tumor excised group (Group 2) in comparison with those receiving sham surgery (Group 1). However, metastatic burden was always reduced in Group 3. An even greater reduction was seen in Group 4. To study the possible involvement of macrophages, the production of prostaglandin-E2 (PGE2) and cytotoxicity of macrophages in these animals were examined. It was found that tumor excision enhanced PGE2 production by macrophages and suppressed their cytotoxicity, while TC inoculation prevented both of these changes. An even greater prevention was observed with PTC inoculation. These results indicate an association among macrophage cytotoxicity, PGE2 production of macrophages, and metastasis. In order to clarify the mechanism for these reactions, we did experiments using adherent splenic macrophages from the four groups of animals.(ABSTRACT TRUNCATED AT 250 WORDS)

[Problems and prevention in using arterial grafts for coronary artery bypass grafting]

The arterial graft has proved to be superior to the saphenous vein graft for coronary bypass grafting (CABG), because of its excellent long-term patency. However, there mains controversial on the choice of the arterial grafts. Six hundreds and twenty seven patients who had CABG using both arterial grafts and saphenous vein grafts, operated upon over 11-years period between 1980 and 1991, have been analysed. Some disadvantages and complications associated with the use of arterial grafts were demonstrated in our series. We discussed, the flow capacity, myocardial protection and postoperative complications in using arterial grafts for CABG.

Absorption and metabolism of pyridoxamine in mice. II. Transformation of pyridoxamine to pyridoxal in intestinal tissues

The absorption of pyridoxamine from the intestine of the mouse was studied in whole animals. [3H]Pyridoxamine was orally administered and the distribution of isotope between the six recognized forms of vitamin B6 was determined in portal blood after the administration. When small doses (1.4 or 14 nmol) were administered, labeled pyridoxamine could hardly be found in the portal blood, although labeled pyridoxal and pyridoxal phosphate were found in the same blood. However, when a large amount (46 or 140 nmol) was given, a significant amount of labeled pyridoxamine was found with labeled pyridoxal and pyridoxal phosphate in the portal blood. These results suggest that a physiological dose of pyridoxamine is rapidly transformed to pyridoxal in the intestinal tissues and then released in the form of pyridoxal into the portal blood.

Evaluation of blood flow at ocular fundus by using laser speckle

We report a method for noninvasively evaluating blood flow at the ocular fundus by using laser speckle phenomena. The intensity fluctuation of speckles scattered from a 1-mm-diameter illuminated area at the fundus is detected and analyzed by the photon-correlation technique, which gives us the relative degree of total blood flows within the probe area. The method is used to evaluate blood flows at the ocular fundus of a rabbit and normal human volunteers. The experimental results show that the present laser speckle method is useful for the relative evaluation of blood flows in the ocular fundus tissue.

The application of 1H NMR chemical shift calculations to diastereotopic groups in proteins

We have calculated chemical shifts for a range of diastereotopic protons in proteins (i.e. methylene protons, and the methyl groups of valine and leucine residues), using a recently optimised method for chemical shift calculation. The calculations are based on crystal structure coordinates, and have been compared with experimental stereospecific assignments. The results indicate that chemical shifts can be used to suggest stereospecific assignments with about 80% probability of being correct, in cases where both the experimental and the calculated chemical shift differences between a pair of diastereotopic protons are greater than 0.3 ppm. Inaccurate calculations are shown to be caused in most cases by differences between crystal and solution structures. Furthermore, chemical shift calculations based on NMR structures are shown to be capable of acting as a further constraint on structure, by limiting the range of side-chain conformations adopted in structures calculated from NMR data.

Coexistence of extracranial internal carotid artery aneurysm and multiple intracranial aneurysms--case report

A rare case of extracranial internal carotid artery (ICA) aneurysm coexisting with intracranial multiple aneurysms in a 64-year-old female is reported. The three intracranial aneurysms were clipped uneventfully by two-stage craniotomies. The extracranial ICA aneurysm at the infratemporal region was excised through a high cervical route and ICA was reconstructed by an end-to-end direct anastomosis. Ours is the first case reported of extra- and intracranial aneurysms surgically treated successfully.

[Selective jugular cannulation for hypothermic retrograde cerebral perfusion in thoracic aortic operations (reverse over the wire-catheter method)]

We have employed hypothermic retrograde total body perfusion via the caval cannulae as a supportive measures to protect the brain and other systemic organs in operations for aortic arch aneurysms or acute aortic dissection. But occasionally unsatisfactory results ensued, because competent valves located in the internal jugular vein near the jugulo-subclavian junction may block retrograde blood flow to the brain from the caval cannula. To cope with this problem, we designed an easy and safe method to cannulate the internal jugular vein transatrially utilizing guidewire and central venous catheter, and thereafter we have used this technique clinically and obtained good results.