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Biomedical subjects

S Homma

Publications and source records attributed to S Homma.

At least 19 recordsLinked to original sources
PubMed1992

Patent foramen ovale as a risk factor for cryptogenic stroke.

OBJECTIVE: To determine and compare the prevalence of patent foramen ovale in patients with stroke of undetermined origin (cryptogenic) and in patients with stroke of determined origin to assess the possible role of patent foramen ovale as a risk factor for cryptogenic stroke. DESIGN: Cross-sectional study with nested case-control analysis. PATIENTS: A total of 146 patients (73 men, 73 women) with acute ischemic stroke referred to the echocardiography laboratory for evaluation. SETTING: Neurovascular Unit and Echocardiography Laboratory, Columbia-Presbyterian Medical Center, New York, New York. MEASUREMENTS: Patients were considered to have strokes of determined origin or cryptogenic strokes according to National Institute of Neurological Disorders and Stroke (NINDS) Stroke Data Bank criteria. The presence of patent foramen ovale was assessed by contrast echocardiography, performed blinded for type of stroke. The association between patent foramen ovale and type of stroke was tested after correcting for patients' demographic variables and stroke risk factors. RESULTS: The overall prevalence of patent foramen ovale was 26 of 146 patients (18%; 95% Cl, 11.4% to 24.6%). Patients with cryptogenic stroke (31%) had a significantly higher prevalence of patent foramen ovale than did patients with an identifiable cause of stroke (69%) in both the younger (less than 55 years; 48% compared with 4%; P less than 0.001) and the older (greater than or equal to 55 years; 38% compared with 8%; P less than 0.001) age groups. Multiple logistic regression analysis was used to identify the presence of a patent foramen ovale as strongly associated with the diagnosis of cryptogenic stroke (odds ratio, 7.2; Cl, 2.4 to 21.7), irrespective of patient age and other stroke risk factors. CONCLUSIONS: Patients with cryptogenic stroke have a higher prevalence of patent foramen ovale than patients with stroke of determined cause in all age groups, even after correcting for the presence of recognized stroke risk factors. This identifies patent foramen ovale as a risk factor for cryptogenic stroke. Regardless of patient age, contrast echocardiography should be considered when the cause of stroke is unknown.

Adult↗
PubMed1992

Activation of mouse macrophages by in vivo and in vitro treatment with a cyanine dye, lumin.

The cyanine photosensitizer, lumin, is a potent macrophage activating agent: 4 days after administration of small amounts of lumin to mice (20-40 ng mouse-1), peritoneal macrophages exhibited a greatly enhanced Fc-mediated ingestion activity; higher doses (more than 3000 ng mouse-1) did not have this effect. The in vitro photodynamic activation of macrophages in mouse peritoneal cells exposed to white fluorescent light (3 J m-2 s-1) was also studied in media containing various concentrations of lumin. A short light exposure (45 J m-2) with 10 ng lumin ml-1 produced a maximum ingestion activity of macrophages. Lumin has absorption peaks at 670 and 760 nm. Therefore we designed experiments in which peritoneal cells were exposed to a red fluorescent light (emission, 660 nm; 0.5 J m-2 s-1). In a medium containing 3 ng lumin ml-1 with 7.5 J m-2 of red light, a markedly enhanced ingestion activity of macrophages was observed. The photodynamic treatment of peritoneal macrophages alone did not stimulate phagocytic activity, but the photodynamic treatment of a mixture of non-adherent (B and T) cells and macrophages resulted in a greatly enhanced ingestion activity of macrophages. Thus non-adherent cells are required for the photodynamic activation of macrophages, implying that an activating factor is generated within the non-adherent cells and transmitted to the macrophages. This hypothesis was confirmed by the observation that co-cultivation of photodynamically treated non-adherent cells with untreated macrophages resulted in a greatly enhanced ingestion capacity.

Animals↗
PubMed1992

Estimation of neural architecture in human brain by means of the dipole tracing method.

The electric source locations of interictal spikes recorded with depth electrodes were estimated by the dipole tracing (DT) method. Three-dimensional coordinates of the active surfaces of the depth electrodes and head geometry of the patient were measured from frontal and sagittal X-ray images and by a special device, respectively. The estimated dipole locations were superimposed on MR images of the patients. The dipole locations estimated in the hippocampal or parahippocampal regions successively moved in a small limited region during the interictal spike's peak. It was suggested that an interictal spike is composed of summated equivalent dipoles generated by hypersynchronization of a cluster of neurons, and that the timing of such hyperexcitation is more or less delayed because of electrical propagation along neuronal clusters which might be separated by sclerotic tissues.

Brain↗
PubMed1992

Hypothalamic osmoregulation for vasopressin release in streptozotocin-diabetic rats in vivo and in vitro.

The central osmoregulation mechanism for vasopressin (VP) release was studied in the streptozotocin diabetic (STZ-DM) rat. Electrical activities of the VP-producing cell in the supraoptic nucleus (SON) were recorded extracellularly and compared with those in the control rat both in vivo and in vitro. Neuronal activities in the periventricular area (PVA) were also recorded in the in vitro experiment. Hyperosmolar stimulation which was done with an intraperitoneal injection of 1.0 M NaCl (4 ml/kg) resulted in an increase in plasma osmolality both of STZ-DM (increased by 14 +/- 2 mOsml/kg H2O) and control rats (15 +/- 3 mOsmol/kg H2O). Increased plasma osmolality caused significant increase in the mean discharge rate of VP-producing cells in the control animals, but only an insignificant change in STZ-DM rats. In the hypothalamic slice preparations incubated in the artificial cerebrospinal fluid (301 +/- 2 mOsml/kg H2O), VP-producing cells in control rats increased their discharge rate linearly as the osmolality (310 +/- 2 and 320 +/- 1 mOsmol/kg H2O) or concentration (10(-8) and 10(-6) M) of angiotensin II (AGII) of the perfusate was increased stepwise, but there was no change in response to either stimulus in STZ-DM rats. On the other hand, there was no difference in sensitivity to osmolality and AGII of PVA neurons in both animal groups. These data indicate that lower sensibility to osmotic change of VP-producing cells in STZ-DM rats may depend, at least partially, upon the disturbance of osmo- and AGII-sensitivity in VP-producing cells themselves, and that these changes seem to be restricted to SON VP-producing cells.

Analysis of Variance↗
PubMed1992

Vasoconstrictor effects of endothelin-1 on myocardium microcirculation studied by the Langendorff perfusion method: differential sensitivities among microvessels.

An intravital fluorescence microscope system was used to investigate the pharmacological effects of endothelin-1 (ET-1) on the coronary microcirculation in the isolated beating hearts of rats. The heart was perfused by retrograde aortic steady flow with an oxygenated Krebs-Ringer solution containing FITC-dextran. Changes in diameters of coronary microvessels accompanying the cumulative injection of ET-1 in the perfusate were observed and recorded with a video camera system. Coronary perfusion pressure was also measured during each experiment. Bolus injections of ET-1 (1-300 pmole) elicited a dose-dependent increase in perfusion pressure from 54 +/- 6 mm Hg (mean +/- SEM; n = 10, before the ET-1 injection) to 144 +/- 9 mm Hg (n = 8, at the ET-1 dose of 300 pmole). A dose-dependent narrowing of microvessels was also observed. This vasoconstriction was especially prominent in small-sized arterioles; the maximum vasoconstriction of the smaller arterioles was significantly higher than that of the larger arterioles (P less than 0.05). The response induced by ET-1 dose of 3-10 pmole was significantly larger in arterioles than in postcapillary venules in the diameter range between 10 and 40 microns. The vasoconstriction produced by ET-1 was inhomogeneous. Some part of bifurcations of arterioles showed a prominent localized vasoconstriction, and occasionally showed a complete luminal obstruction. Such a segmental vasospasm might be attributed to localized sensitivities of arterioles to ET-1. These findings suggest that ET-1 may have an important role in governing the coronary resistance and regulating the capillary flow in the myocardium.

Animals↗
PubMed1992

Pulmonary vascular lesions in the adult respiratory distress syndrome caused by inhalation of zinc chloride smoke: a morphometric study.

Two soldiers were fatally injured by accidental inhalation of zinc chloride (ZnCl2) from a smoke bomb. Although exposed to a relatively short but high smoke concentration, acute injury was minor and for 10 days the patients were clinically satisfactory. Unexpectedly, both then rapidly developed features typical of severe adult respiratory distress syndrome with pulmonary hypertension. Intubation and mechanical ventilation were instigated on day 15 (patient no. 1) and day 12 (patient no. 2) after the inhalation, but death followed at days 25 and 32, respectively. Lung vascular injury was assessed by angiography and morphometric techniques. The lungs showed extensive interstitial and intra-alveolar space fibrosis. Vessels showed a significant lumen reduction by contracture (that is, reduction in vessel external diameter) affecting preacinar and intraacinar arterial and venous segments, the extent of injury suggesting that hexite causes more severe venous injury than seen in other types of adult respiratory distress syndrome. In microvessels there was obliteration and widespread occlusion by endothelial cell proliferation and clot. No evidence of infection was identified during life or at autopsy. It is unclear whether the long lag time was due to the fact that the infection was not a complicating event or because steroids, administered prophylactically, had sufficed to delay, but not to prevent, the amplification of injury that seems responsible for the adult respiratory distress syndrome.

Adult↗
PubMed1992

Development of serotoninergic system in the brain and spinal cord of the chick.

(1) Development of serotonin positive cells and fibers was immunohistochemically studied by the use of an antibody against serotonin. (2) Serotoninergic neurons were first observed in the immature rohmbencephalon raphe nuclei on embryonic day (E)4, where two clusters of serotonin positive neurons were located: one observed at the rostral part of the rohmbencephalon corresponding to the dorsal raphe nuclei had many serotonin positive cells: the other located at the caudal part of the rohmbencephalon corresponding to the medullary raphe nuclei of the adult animals had only a small number of serotoninergic cells. (3) By E8 the number of serotonin positive cells in the brain stem increased, and virtually all the raphe nuclei found in an adult animal were located. (4) Serotonin positive fibers in the marginal layer reached up to the diencephalon and telencephalon on E6 and E8, respectively. (5) Serotonin positive cells were found beside the midline regions in the ventral part of the spinal cord of the embryonic as well as posthatching chick. (6) Because almost all the serotoninergic fibers in the spinal cord originated from the brain stem raphe nuclei, propriospinal serotonin positive cells were considered as phylogenetic vestiges. (7) Serotoninergic fibers were first found in the marginal layer of the cervical and lumbar spinal cord on E6 and E8, respectively. (8) There was a waiting period of a few days before they penetrated into the mantle layer. (9) Terminal arbolization of the serotoninergic fibers started from late embryonic periods (E16 less than), and was maximized within one week of hatching. (10) Thereafter the density of serotonin positive fibers decreased in all the regions of the spinal cord. (11) Developmental changes of the density of serotonin determined with a high performance liquid chromatography were the same as those determined through immunohistochemistry. Namely the density of serotonin increased linearly from E6 to hatching period, and reached the maximum value one week posthatching. (12( The density of the serotonin in the adult spinal cord was about half of the maximum value. (13) It is to say that the densities of serotonin and serotoninergic fibers transiently increased around one week posthatching. (14) Following the transient increase serotoninergic fibers were eliminated from the neuropil, the fibers were localized in the specific regions of the motor nucleus: motor neuron pools of extensor muscles of the hip joint in the lumbosacral spinal cord.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Spinal arachnoid cyst in a newborn infant.

A male infant was born with asphyxia following a prolonged breech delivery at 39 weeks of gestation. He had a chylohemothorax from birth. Soon after birth he exhibited flaccid paraplegia with an absence of deep tendon reflexes in the lower extremities. At 17 days of age, magnetic resonance imaging (MRI) disclosed a hypodense area in the thoracic cord between C7 and Th4 in T1-weighted images, and spinal sonography revealed an echo-free space compressing the spinal cord in the same region observed with MRI. A spinal cyst was removed surgically at 24 days of age. The cyst was confirmed by pathology to be a true arachnoid cyst between C7 and Th4. The cause of this cyst may have been a spinal cord injury during the perinatal period.

Arachnoid Cysts↗
PubMed1992

Cholesterol emboli neuropathy.

We report the clinical and pathologic features of a patient with peripheral neuropathy that was the first clinical expression of cholesterol emboli syndrome (CES). Biopsy of skeletal muscle and peripheral nerve revealed cholesterol clefts in lumens of small arteries, necrotizing arteritis, and severe degeneration of peripheral and intramuscular nerves. At autopsy, the peripheral nervous system was extensively affected by similar changes. We conclude that (1) peripheral neuropathy may be the initial manifestation of CES. Presumably, deposition of cholesterol leads to arteritis. (2) The underlying pathology of CES neuropathy is chronic axonal degeneration, possibly due to chronic ischemia of epineurial arteries. (3) Muscle biopsy is important in the antemortem diagnosis of CES. Nerve biopsy may show involvement of epineurial vessels. (4) CES may resemble polyarteritis nodosa clinically and pathologically. (5) CES may be under-recognized and should be included in the differential diagnosis of any neuropathy of uncertain cause, particularly when there is a history of vascular catheterization, or severe aortic atherosclerosis.

Aged↗
PubMed1992

Isolation and characterization of macrocarpals B--G antibacterial compounds from Eucalyptus macrocarpa.

Six novel phloroglucinol dialdehyde diterpene derivatives (macrocarpals B--G), which have antibacterial activity, were isolated from leaves of Eucalyptus macrocarpa. These compounds have closely related structures, the molecular formula for B--F being C28H40O6, and that of G being C28H38O5. The structures of macrocarpals B, D, and G were analyzed by means of NMR analyses.

Anti-Bacterial Agents↗
PubMed1992

Purification and some properties of chlorogenic acid oxidase from apple (Malus pumila).

Chlorogenic acid oxidase was extensively purified to homogeneity from apple flesh (Malus pumila cv. Fuji). The enzyme was purified 470-fold, with a total yield close to 70% from the plastid fraction by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography. The molecular weight was determined to be 65,000 by both SDS-PAGE and gel filtration chromatography. The optimum pH for the enzyme activity was around 4.0, and the enzyme was stable in the range of pH 6-8. The pI obtained by isoelectrofocusing was 5.4, and the N-terminal amino acid sequence was N-Asp-Pro-Leu-Ala-Pro-Pro-. The reaction rate of the purified enzyme was much larger for chlorogenic acid than for other o-diphenols such as (+)-catechin, (-)-epicatechin and 4-methylcatechol, and the enzyme lacked both cresolase activity and p-diphenol oxidase activity. The Km value for the enzyme was found to be 122 microM toward chlorogenic acid. The purified enzyme had far less thermal stability than the enzyme of the plastid fraction. Diethyl-dithiocarbamate, sodium azide, o-phenanthroline and sodium fluoride markedly inhibited the enzyme activity.

Amino Acid Sequence↗
PubMed1992

Reversible pulmonary artery obstruction in a patient with bronchogenic carcinoma. Diagnosis by two-dimensional and Doppler echocardiography.

Neoplastic invasion of the pulmonary arteries, although common, rarely results in obstruction to right ventricular outflow. We report an unusual case of severe pulmonary hypertension, right ventricular dilatation, and righ ventricular dysfunction resulting from pulmonary arterial compression by bronchogenic carcinoma. The diagnosis was made by two-dimensional and Doppler echocardiography and supported by computed tomographic findings. Echocardiography was used to follow the patient's response to therapy and documented the subsequent resolution of pulmonary arterial obstruction.

Carcinoma, Bronchogenic↗
PubMed1992

An improved method for measurement of sweat expulsions during profuse sweating.

We present an improved ventilated-capsule method of recording for clear sweat expulsion patterns using nitrogen gas as a carrier gas heated to promote sweat evaporation. With this method, sweat expulsion patterns were more clearly recorded than with the conventional ventilated-capsule method. Taking the derivatives of these recordings of sweating expulsions could eliminate slow fluctuation components in the patterns of sweating. The results indicate that this method is useful in providing more-accurate measurements of sweat expulsion frequencies during profuse sweating.

Adult↗
PubMed1991

Vitamin D3 binding protein (group-specific component) is a precursor for the macrophage-activating signal factor from lysophosphatidylcholine-treated lymphocytes.

A brief (30 min) treatment of mouse peritoneal cells (mixture of nonadherent lymphocytes and adherent macrophages) with 1-20 micrograms of lysophosphatidylcholine (lyso-PC) per ml in serum-supplemented RPMI medium 1640, followed by a 3-hr cultivation of the adherent cells alone, results in a greatly enhanced Fc receptor-mediated phagocytic activity of macrophages. This rapid process of macrophage activation was found to require a serum factor, the vitamin D3 binding protein (the human protein is known as group-specific component; Gc). Efficient activation of macrophages was achieved by using medium containing purified human Gc protein. Analysis of intercellular signal transmission among nonadherent (B and T) cells revealed that lyso-PC-treated B cells modify Gc protein to yield a proactivating factor, which can be converted by T cells to the macrophage-activating factor. This rapid generation process of the macrophage-activating factor was also demonstrated by stepwise incubation of Gc protein with lyso-PC-treated B-cell ghosts and untreated T-cell ghosts, suggesting that Gc protein is modified by preexisting membranous enzymes to yield the macrophage-activating factor. Incubation of Gc protein with a mixture of beta-galactosidase and sialidase efficiently generated the macrophage-activating factor. Stepwise incubation of Gc protein with B- or T-cell ghosts and sialidase or beta-galactosidase revealed that Gc protein is modified by beta-galactosidase of B cells and sialidase of T cells to yield the macrophage-activating factor. Administration to mice of a minute amount (4-10 pg per mouse) of in vitro, enzymatically generated macrophage-activating factor resulted in a greatly enhanced (3- to 7-fold) ingestion activity of macrophages.

Animals↗