Complex propagation of surface waves on soft gels.
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Journal Article↗
Biomedical subjects
K Sakai
Publications and source records attributed to K Sakai.
Effect of bilateral 6-OHDA lesions of the substantia nigra on locomotor activity in the rat.
Previous parkinsonian rat models have utilized stereotactic 6-OHDA injections to completely lesion the dopaminergic mesostriatal system on one side. Recently, hemiparkinsonian rat models in which the mesolimbic system is left intact have been developed. The selective, partial lesion models better mimic the neuropathology of human parkinsonism in which there is usually an incomplete destruction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and a relative sparing of ventral tegmental area (VTA) cell groups. However, such hemiparkinsonian models which possess dopaminergic asymmetry cannot demonstrate bradykinesia, one of the main symptoms in human parkinsonism. Meanwhile, bilateral lesions of the ascending forebrain dopaminergic system have been reported to induce severe aphagia, adipsia and akinesia. We, therefore, undertook development of a bilateral partial SNpc lesion model which also spares the VTA on both sides. We have investigated spontaneous locomotor activities as well as amphetamine, apomorphine and levodopa induced activities during a subchronic period of up to 27 days after the bilateral lesion. Three activity parameters i.e. horizontal activity, vertical activity and distance analyzed. Spontaneous activity was significantly decreased in animals with extensive (> 80%) SNpc lesions on both sides. Animals with a > 95% lesion were severely aphagia and adipsia. Responses to amphetamine and apomorphine were variable. It is possible that in some cases the bilateral SNpc neurons were not equally damaged, which could cause the enhanced rotational behavior. Bradykinetic rats displayed on the average, a > 20% decline in horizontal activity, a > 40% decline in vertical activity and a > 30% decline in distance traveled after the lesion.(ABSTRACT TRUNCATED AT 250 WORDS)
Amphetamine↗
Excitation of the motor cortex associated with the E2 phase of cutaneous reflexes in man.
We investigated excitability changes of the motor cortex associated with the E2 phase of cutaneous reflexes in the first dorsal interosseous muscle using transcranial electrical and magnetic stimulation of the motor cortex in humans. EMG responses to combined cutaneous and weak magnetic cortical stimulation, which were elicited during the E2 phase of cutaneous reflexes, were larger than those by the same magnetic cortical stimulation alone. This facilitatory effect was reduced or even inhibitory effect was seen when the intensity of cortical stimulation was increased. Responses to weak electrical cortical stimulation were less affected by the combined cutaneous stimulation. The same facilitatory effect on responses to weak magnetic cortical stimulation was also observed in single motor unit recordings, too. Dissociation between facilitatory effects on the responses evoked by weak magnetic and weak electrical cortical stimulations suggests that the motor cortical excitability is increased in association with the E2 phase. The present results are consistent with the hypothesis that the E2 phase is a kind of transcortical reflex.
Adult↗
Relation of impaired left ventricular function in mitral regurgitation to left ventricular contractile state after mitral valve replacement.
To reevaluate the postoperative contractile state and survival, 34 patients (19 men and 15 women; average age 45 years, range 23 to 65) undergoing conventional mitral valve replacement between 1980 and 1990 were studied. There were 5 cardiac deaths (2 early and 3 late). Four of 5 deaths occurred in patients who had a preoperative left ventricular end-systolic volume index > 100 ml/m2. Sixteen patients with an end-systolic volume index < 100 ml/m2 (group I), and 5 with an index > 100 ml/m2 (group II) underwent repeat catheterization 8 months (range 4 to 17) after surgery. The ratio of end-systolic wall stress to end-systolic volume index increased significantly after surgery in group I, whereas it remained reduced in group II. The postoperative end-systolic wall stress/volume index ratio correlated significantly with the preoperative end-systolic volume index (p < 0.001). In the relation between end-systolic wall stress and ejection fraction, all patients in group II had values that were less than the 95% confidence limits for the normal relation. In conclusion, patients with a preoperative end-systolic volume index > 100 ml/m2 appeared to be at high risk of incurring irreversible depressed myocardial contractility, with a high postoperative mortality.
Adult↗
Vascularized periosteal bone graft from the supracondylar region of the femur.
Free, vascularized thin corticoperiosteal grafts and small periosteal bone grafts harvested from the supracondylar region of the femur are described. These grafts are nourished from the articular branch of the descending genicular artery and vein. Thin corticoperiosteal grafts consist of periosteum with a thin layer of outer cortical bone and include the cambium layer, which has a better osteogenic capacity. This graft is elastic and readily conforms to the recipient bed configuration. Thin corticoperiosteal grafts were used to treat 11 patients with fracture non-union of an upper extremity that had no massive bone defects. Early, rapid union occurred in all patients except three: one in which the anastomosed vessel became obstructed and two in which the internal fixation of the fracture was unsecured. The small bone grafts consist of periosteum, full thickness cortex, and the underlying cancellous bone. This graft can be successfully harvested without disturbing the vascularity, unlike the currently used vascularized bone grafts. This graft was used to treat three patients with avascular necrosis of the body of the talus and could prevent the necrotic talus body from progressive collapse in patients in early stages of the disease. One patient with an infectious bone defect of the first metatarsal bone was successfully treated by vascularized bone graft with an accompanying skin flap.
Adolescent↗
Heterotopic vascularized growth plate transfer in juvenile dogs.
Prior animal studies of vascularized epiphyseal transfers placed growth plates in 2 bone systems where the independent growth of epiphyses and their response to altered stresses has been difficult to assess. This study assessed growth of vascularized ulnar epiphyses transferred to the ipsilateral humerus of 12-week-old puppies. Growth was permitted by a specially designed extensible plate. Control groups showed that humeral dissection, osteotomy and ostectomy alone do not stimulate growth. In 4 puppies initial growth of the transferred epiphysis was seen but late collapse and formation of bridging callus occurred so that overall humeral length at maturity was not significantly different from control humeri. Physical forces inherent in heterotopic transfer may preclude long term growth of transferred epiphyses particularly in sites of higher relative load. The extensible plate used here may be a useful device in the fixation of transferred epiphyses with growth potential.
Animals↗
The human genes for desmogleins (DSG1 and DSG3) are located in a small region on chromosome 18q12.
Desmoglein is a transmembrane glycoprotein component of desmosomes in vertebrate epithelial cells. Two of the three currently known desmogleins are the autoantigens of autoimmune skin blistering diseases, pemphigus vulgaris and pemphigus foliaceus, in which autoantibodies cause the loss of cell adhesion of keratinocytes with resultant blister formation. In this study, the genes for two autoantigens (DSG1 for pemphigus foliaceus and DSG3 for pemphigus vulgaris) were mapped on band q12 of human chromosome 18 by fluorescence in situ hybridization. Furthermore, both genes were localized on a 320-kb genomic fragment separated by pulsed-field gel electrophoresis. These results suggest the possibility of a cluster for the desmoglein gene family on chromosome 18.
Animals↗
Localization of surfactant protein A (SP-A) in alveolar macrophage subpopulations of normal and fibrotic rat lung.
The colocalization of surfactant protein A (SP-A) and the alveolar macrophage markers ED1 and RM-1, as well as various lectins of the N-acetyl-galactosamine group [Maclura pomifera lectin (MPA), Dolichos biflorus lectin (DBA), soybean agglutinin (SBA)] and of the mannose group [Canavalia ensiformis lectin (ConA), Galanthus nivalis lectin (GNA)] was studied in normal and fibrotic rat lung tissues. In normal tissue, SP-A was located preferentially in the alveolar macrophage subpopulation lacking specific binding sites for lectins of the N-acetylgalactosamine group (DBA and SBA), although 50% of MPA-binding macrophages contained SP-A. The ED1-positive cells were SP-A-negative, whereas SP-A uptake could be detected among the RM-1 immunoreactive as well as the ConA and GNA binding macrophages. In fibrotic lung tissue, however, a small number of DBA and SBA binding macrophages contained SP-A and the percentage of GNA and ConA binding alveolar macrophages exhibiting SP-A immunoreactivity was reduced. Additionally, the number of ED1+/SP-A+ macrophages was found to be increased. Immunoelectron microscopy revealed accumulation of SP-A in the extracellular space. The differing SP-A content in different alveolar macrophage subpopulations suggests a more complex mechanism of uptake and degradation of surfactant proteins in normal and pathological conditions, which cannot simply be explained by the glycoconjugate pattern on the surface of alveolar macrophages.
Animals↗
Regional cerebral blood flow measured with N-isopropyl-p-[123I]iodoamphetamine single-photon emission tomography in patients with Joseph disease.
Regional cerebral blood flow (rCBF) was measured in five Japanese patients who were clinically diagnosed as having Joseph disease, also called Machado-Joseph disease or Azorean disease, using N-isopropyl-p-[123I]iodoamphetamine (IMP) and single-photon emission tomography (SPECT). Cerebellar atrophy was evaluated by a five-step rating scale as defined on X-ray computed tomography (X-CT). Compared with ten age-matched normal controls (mean cerebellar CBF +/- SD: 66.9 +/- 6.6 ml/100 g/min), rCBF in patients with Joseph disease was significantly decreased in the cerebellum (mean +/- SD: 50.2 +/- 7.3 ml/100 g/min). No significant relationship, however, was found between the decrease in rCBF in the cerebellum and the degree of cerebellar atrophy on X-CT. rCBF in the cerebellum was minimally decreased in one patient who had severe cerebellar atrophy and in two patients with moderate atrophy. These data may support the findings that Purkinje cells in the cerebellum are almost normal in Joseph disease, and that the granular and molecular layers remain intact in spite of cortical atrophy of the cerebellum. It is concluded that [123I]-IMP SPET is able to identify pathological and metabolic changes in the cerebellum that do not appear on X-CT or magnetic resonance imaging, and thus is useful for the diagnosis of Joseph disease.
Adult↗
Echocardiographic findings of myeloblastoma in the heart.
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Adolescent↗
Long-term variations of arterial blood pressure during sleep in freely moving cats.
Using a new telemetric system for arterial blood pressure recordings, we have investigated long-term postoperative changes in blood pressure during sleep in freely moving cats. Particular attention was paid to the transitional periods at the beginning and end of paradoxical sleep (PS), as well as to the relationship between the blood pressure and ponto-geniculo-occipital (PGO) waves. In the initial postoperative stage lasting 2 to 5 days, the blood pressure decreased during the transition from slow wave sleep (SWS) to PS and maintained its lower level until the end of PS. In contrast, in the later chronic stage, the blood pressure increased tonically during the transition from SWS to PS and maintained its higher level throughout PS on which several phasic rises in blood pressure were superimposed. A significant increase in arterial pressure during the transitional period began shortly after the first appearance of PGO waves. On the other hand, significant phasic rises in arterial pressure during PS shortly preceded the onset of PGO wave bursts.
Animals↗
Visual imagery: an interaction between memory retrieval and focal attention.
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Attention↗
Promotion of sleep by prostaglandin D2 in rats made insomniac by pretreatment with para-chlorophenylalanine.
The correlation between the somnogenic effect of prostaglandin (PG) D2 and the serotoninergic system was examined in freely-moving rats (n = 64) by use of a continuous infusion method. Rats pretreated with para-chlorophenylalanine (PCPA: 450 mg/kg body weight, i.p.) or non-PCPA-pretreated rats received infusion of PGD2, serotonin, or its direct precursor, 5-hydroxytryptophan (5HTP), into their third cerebral ventricle at a rate of 100 pmol/0.2 microliter/min between 11:00 and 17:00 h. In the PCPA-pretreated insomniac rats, PGD2 infusion resulted in an immediate increase in slow-wave sleep (SWS) and an increase with a 2-h latency in paradoxical sleep (PS). The total amounts of SWS and PS during the PGD2-infusion period were 151% and 154% of the respective control values. These results indicate that inhibition of the biosynthesis of serotonin and 5HTP by PCPA marginally affects the sleep-promoting effect of PGD2. The transient sleep restoration produced by 5HTP infusion into PCPA-pretreated rats was hardly affected by the simultaneous infusion (200 pmol/0.2 microliter/min; 07:00-17:00 h) of diclofenac sodium, an inhibitor of cyclo-oxygenase, suggesting that PGD2 production is not critically involved in the sleep restoration by 5HTP. The sleep-promoting property of PGD2 is thus probably independent of the serotoninergic modulation of sleep-wake activity.
5-Hydroxytryptophan↗
The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses.
The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80.8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82-100%) or by sleeping 2 to 4 h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0.95, p < 0.001). This result suggests that more than 16 h between work shifts is required to allow more than 7 h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2.8 years) slept less and spent less time on free-time activities than did other nurses.
Activities of Daily Living↗
Cell-free formation of disulfide-bonded multimer from isolated plasma fibronectin in the presence of a low concentration of SH reagent under a physiological condition.
Purified plasma fibronectin in Tris-buffered saline aggregated on incubation at 37 degrees C in the presence of dithiothreitol without the presence of cells. On SDS polyacrylamide gel electrophoresis without reduction, dimeric fibronectin showed a 460 kDa band, while the protein band of aggregated fibronectin remained at the top of the running gel. The aggregate was a disulfide-bonded multimer, since both the dimeric and the multimeric fibronectins migrated as 230 kDa polypeptides after reduction. The multimer formation required SH reagent and proceeded faster with higher SH concentration, suggesting the occurrence of a disulfide exchange reaction during the aggregation. Since dimeric fibronectin with carboxymethylated sulfhydryl groups also formed multimers under the same condition, the free sulfhydryl groups of dimeric fibronectin may not be involved in the multimer formation, suggesting involvement of disulfide exchange from intramolecular bonds to intermolecular bonds. The multimerization was not influenced by Na+, Ca2+, or EDTA, while urea-treated fibronectin required a higher concentration of dithiothreitol for multimer formation. Fibronectin partially degraded by m-calpain did not form multimers. The multimeric fibronectin retained heparin-binding and cell attachment activities, but had lost gelatin-binding activity. Involvement of the terminal regions containing type I and type II repeats was suggested in the interaction of pFN leading to the multimerization.
Animals↗
Effects of MDL 28,133A, a 5-HT2 receptor antagonist, on platelet aggregation and coronary thrombosis in dogs.
We wished to characterize MDL 28,133A (1-(4-fluorophenyl)-2-[4-[(4-methanesulfonamidophenyl)carbonyl]-1- piperidinyl-ethanone HCl), a potent 5-HT2 receptor antagonist, on platelet aggregation and platelet thrombosis and determined its effect on thrombolysis with streptokinase (SK) in dogs with coronary thrombosis. MDL 28,133A and ritanserin, 0.3-1 microM, competitively inhibited 5-HT-induced platelet aggregation in dog platelet-rich plasma (PRP) in vitro. The pA2 values and slopes were 6.29 +/- 0.09, -0.96 +/- 0.14, and 6.58 +/- 0.09, =1.64 +/- 0.34 for MDL 28,133A and ritanserin, respectively, suggesting that both agents are similar in potency to 5-HT2 receptor antagonists. MDL 28,133A (0.01 mg/kg, p.o.) produced inhibition of arachidonic acid-induced platelet aggregation in whole blood from conscious dogs ex vivo for > or = 2 h, indicating oral bioavailability. The magnitude and duration of the effect of MDL 28,133A on platelet aggregation in whole blood was similar to that of ketanserin (2.5 mg/kg, p.o.). MDL 28,133A (0.001-0.03 mg/kg, i.v.) completely abolished cyclic flow reductions (CFRs) in stenosed and partially deendothelialized left anterior descending coronary arteries of anesthetized dogs for at least 120 min without affecting systemic blood pressure (BP) and heart rate, thus indicating that MDL 28,133A is a potent antithrombotic agent. Ketanserin (0.5 mg/kg, i.v.) also abolished CFRs, but produced a significant decrease in systemic BP as well. MDL 28,133A (0.001 mg/kg, i.v.) shortened time to reperfusion (15 +/- 1 vs. 36 +/- 8 min), prolonged time to reocclusion (112 +/- 6 vs. 85 +/- 6 min), and increased total volume reflow (20 +/- 2 vs. 10 +/- 2%) in dogs with coronary artery thrombosis undergoing thrombolysis with SK (1,000 U/min, i.a.). Reocclusion rate was not affected by MDL 28,133A (4 of 5 vs. 4 of 6). Treatment with heparin (150 U/kg, i.v. every hour for 2 h) alone or in combination with MDL 28,133A did not improve time to reperfusion but enhanced total volume reflow and prevented reocclusion. MDL 28,133A is a potent 5-HT2 receptor antagonist that inhibits platelet thrombosis and facilitates thrombolysis in vivo. The impeding effect of MDL 28,133A in coronary thrombosis and the lack of hemodynamic effects suggests that MDL 28,133A may be of benefit in treatment of hyperthrombotic conditions without having hemodynamic side effects.
Administration, Oral↗
Hepatic encephalopathy with increased cerebral blood flow in SPECT and MRI abnormalities in the basal ganglia.
A case of hepatic encephalopathy with increased cerebral blood flow in single-photon emission computed tomography (SPECT) and abnormalities upon magnetic resonance imaging (MRI) is reported. SPECT showed increased blood flow exceeding 70 ml/100 g/min in the cerebellum, basal ganglia and cerebral cortex, with hyperammonemia and abnormal electroencephalographic signs showing severe generalized slowing. SPECT data and MRI might reflect abnormal metabolism and neuropathological changes in hepatic encephalopathy.
Antiparkinson Agents↗
In vitro evaluation of platelet/biomaterial interactions in an epifluorescent video microscopy combined with a parallel plate flow cell.
Suitable evaluation systems are critical for ranking various biomaterials in order to develop a method to design and synthesize nonthrombogenic biomaterials. We have recently developed an in vitro test system to evaluate platelet/biomaterial interactions in whole blood. The system consists of a parallel plate flow cell and epifluorescent video microscopy (EVM). A glass coverslip coated with a polymer was incorporated into the flow cell, and blood was perfused using a syringe pump via a polymer-coated PVC tubing connected to the flow cell. Whole human blood was anticoagulated with heparin (2 U/ml), and the platelets were labeled with the fluorescent dye mepacrine (5 microM). This system permitted real-time and dynamic observations of platelet/biomaterial interactions in whole blood under a defined flow condition. In order to evaluate the feasibility of this system, two different segmented polyether-polyurethanes (SPEUs), PU-PTMG(650) and PU-PTMG(2000), were chosen as test polymers. Surface characteristics verified with electron spectroscopy for chemical analysis (ESCA) and contact angle measurements showed similar results in both SPEUs. Blood was perfused at a wall shear rate of 200 s-1 for 20 min. Excitation light was applied for 2 s at 1 min intervals. The real-time image was then analyzed at each time point for the percentage of surface area of platelet coverage. Plasma beta-thromboglobulin (beta-TG) levels were also measured before and after each run. PU-PTMG(650) showed a significantly higher number of adhered platelets than PU-PTMG(2000) at each time point.(ABSTRACT TRUNCATED AT 250 WORDS)
Biocompatible Materials↗