Urinary excretion of histamine in renal transplant patients.
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Adolescent↗
Biomedical subjects
J K Chang
Publications and source records attributed to J K Chang.
Immunohistochemical localization of dynorphin (1-8) in hypothalamic magnocellular neurons: evidence for absence of proenkephalin.
Dynorphin(1-8) immunoreactivity was visualized by immunohistofluorescence in hypothalamic magnocellular neurons of the rat. No immunoreactive met-enkephalin-Arg6-Gly7-Leu8, a fragment of the adrenal medulla pro-enkephalin molecule, was detected in magnocellular neurons. However, a strong met-enkephalin-Arg6-Gly7-Leu8-like immunostaining was seen in other regions of the brain. These results suggest that in magnocellular neurons dynorphin(1-8) exists independently from pro-enkephalin and therefore the magnocellular neurons represent a third opioid peptide neuronal system in brain. These observations, however, do not rule out a coexistence of proenkephalin and dynorphin-related peptides in other regions of the brain.
Animals↗
Dynorphin(1-10)amide: a potent and selective analog of dynorphin(1-13).
Dynorphin(1-10)amide was more potent than Dynorphin(1-13) in inhibiting the twitch of the mouse vas deferens (IC50 of Dynorphin(1-10)amide = 0.3 nM and IC50 of Dynorphin (1-13) = 4.0 nM). Binding assays indicated that two opioid peptides had similar profiles in that they enhanced dihydromorphine (DHM) binding in picomolar concentrations but displaced DHM binding in nanomolar concentrations (IC50 for Dynorphin(1-10)amide = 5 nM). In the mouse tail-flick assay, however, Dynorphin(1-10)amide showed a more selective action on morphine-induced analgesia. Although Dynorphin(1-10)amide had no significant analgesic activity by itself, it differed from the (1-13) analog by neither potentiating nor antagonizing morphine in naive animals. In tolerant animals, on the other hand, 50 microgram of this analog administered icv shifted the ED50 of morphine from 43.0(33.0-55.9) to 17.0 (12.4-23.3). Thus, Dynorphin(1-10)amide appears to be a more potent and selective analog of Dynorphin(1-13).
Analgesia↗
In vitro potentiation of the activity of synthetic ovine corticotropin-releasing factor by arginine vasopressin.
The ability of arginine vasopressin (AVP) to potentiate the actions of synthetic ovine corticotropin-releasing factor (CRF) was examined using anterior pituitary fragments. Marked potentiation of ACTH release was observed upon incubating the fragments with a combination of 2 nM AVP and 1 nM CRF. Potentiation of CRF-induced ACTH release was also observed when the fragments were incubated with a combination of 1 nM AVP and 0.5 nM CRF. These results suggest that AVP may play a role in the release of ACTH from the adenohypophysis.
Adrenocorticotropic Hormone↗
Immunocytochemical localization of CRF in the ovine hypothalamus.
A population of neuronal cell bodies and their fiber pathways have been elucidated within the ovine hypothalamus. The immunoreactive neurons were located in the anterior and dorsal hypothalamus interspersed throughout the paraventricular nucleus. These perikarya were only observed when an antiserum that was generated against the C-terminal of CRF was employed. A dense fiber projection traversed the medial-basal hypothalamus and ended within the palisade-contact zone of the median eminence and neural stem. Fibers were revealed by antisera generated against both the N-terminal and the C-terminal of CRF. Antisera pre-absorbed with synthetic CRF failed to yield immunoreactivity.
Animals↗
Characterization and localization of atriopeptin in rat atrium.
An antiserum specific for atriopeptin was used to characterize and localize atriopeptin-like immunoreactive material in rat atrium by radioimmunoassay and immunohistochemical techniques. The antiserum recognizes atriopeptin I, atriopeptin III, and alpha-human atrial natriuretic polypeptide, but does not recognize met-enkephalin, cholecystokinin, dynorphin A, bradykinin, substance P, or beta-endorphin. A high content of atriopeptin was found in crude extracts of rat atria, as compared to ventricles, and the atriopeptin-like immunoreactive material was found to be located exclusively in granules within atrial cardiocytes. Fractionation of the immunoreactive material by gel filtration and reverse-phase HPLC revealed the presence of multiple atriopeptins.
Animals↗
Alpha-human atrial natriuretic polypeptide (alpha-hANP) in normal volunteers and patients with heart failure or hypertension.
The presence of alpha-hANP immunoreactive material in human heart and plasma was investigated with a specific and sensitive radioimmunoassay and immunohistochemical method. It was found that alpha-hANP immunoreactive staining of specific atrial granules was located around the nucleus of atrial cardiocytes. No immunoreactive staining was found in the ventricle. The content of immunoreactive hANP was 0.5 pmol/mg protein in the atria and 0.11 +/- 0.01 pmol/ml in the plasma of 26 normal volunteers. In 16 patients with congestive heart failure and 26 patients with essential hypertension, the plasma level of immunoreactive alpha-hANP was significantly lower than that in normal humans. The above evidence indicate that alpha-hANP is a putative hormone secreted by human atrium. A relative shortage of alpha-hANP in the circulatory system may be involved in the mechanism of heart failure and hypertension.
Atrial Natriuretic Factor↗
Calcitonin gene-related peptide (CGRP) in normotensive and spontaneously hypertensive rats.
With the techniques of specific radioimmunoassay and gel filtration it was found that CGRP was distributed in various tissues of normotensive (WKY) and spontaneously hypertensive rats (SHR) with the highest concentration in the lumbar spinal cord (1197 +/- 94.8 pg/mg tissue) and the lowest in the auricle (15.0 +/- 2.1 pg/mg tissue). In comparison with WKY, CGRP concentration in the plasma was decreased and in the abdominal aorta and hypothalamus was increased in SHR. Gel filtration revealed only one major CGRP molecular form in the tissues. In addition, CGRP reduced the mean arterial pressure (MAP) in SHR in a dose-dependent manner. These data suggest that CGRP may play an important role in the pathogenesis of hypertension and its possible therapy.
Animals↗
Pituitary gland. Variable signal intensities on MRI. A pictorial essay.
The anterior pituitary gland may exhibit high signal on T1-weighted (T1w) images and/or low signal on T2-weighted (T2w) images in several normal and pathological states. High T1w signal may be seen in normal fetuses, neonates, and in pregnant and postpartum women. It may also occur in Rathke's cleft cyst, craniopharyngioma, subacute hemorrhage, manganese deposition, melanoma, dermoid, and lipoma. Low T2w signal may be seen in hemorrhage, calcification, cystic lesion, hemochromatosis, melanoma, and vascular lesions. These are described and illustrated.
Adult↗
Assistive devices in the rehabilitation on patients with electrical burns--three case reports.
Limb amputation is a devastating sequela in patients with high-voltage electrical injuries, which may result in permanent disability. It is vital for rehabilitation professionals to assist patients with amputations to maximize their residual function. This can be done using a myriad of therapeutic adaptation methods such as orthotics, prosthetics, and assistive devices so that an optimal performance in daily activities can be achieved. This article describes how 3 patients, after electrical trauma with various levels of amputation, benefited from customized assistive devices, which are simple but effective. Patients' functioning in self-care, home, and work activities was improved. This, in turn, led to an enhanced quality of life. In addition, guidelines for fabrication of assistive devices are formulated.
Activities of Daily Living↗
Hemodynamic effects of centrally administered adrenomedullin (13-52) in anesthetized rats.
This study was conducted to investigate the effect of intracerebroventricular administration of adrenomedullin (13-52) [ADM(13-52)], a novel hypotensive peptide, on the hemodynamic parameters of anesthetized rats. ADM(13-52) was administered centrally in a dose of 0.4-3.2 nmol/kg. It provoked marked, prolonged and dose-dependent increases in mean arterial blood pressure, heart rate, stroke volume, cardiac index, left ventricular pressure, left ventricular dp/dtmax and dp/dtmin, but reduction in total peripheral resistance index. In addition, intracerebroventricular administration of ADM(13-52; 1.6 nmol/kg) provoked a marked increase in renal sympathetic nerve activity. Intracerebroventricular administration of artificial cerebrospinal fluid had no effect on the hemodynamic parameters and renal sympathetic nerve activity. The results indicate that ADM(13-52) exerts a central action on the cardiovascular system. The mechanisms of hemodynamic changes induced by central ADM(13-52) were preliminarily analyzed in this study. ADM might play a role in the central control of the cardiovascular system, although the confirmed mechanisms and the physiological implications are undetermined.
Adrenomedullin↗
Craniocervical junction venous anatomy on enhanced MR images: the suboccipital cavernous sinus.
BACKGROUND AND PURPOSE: The suboccipital cavernous sinus, a vertebral venous plexus surrounding the horizontal portion of the vertebral artery at the skull base, provides an alternative pathway of cranial venous drainage by virtue of its connections to the cranial dural sinuses, the vertebral venous plexus, and the jugular venous system. Knowledge of the anatomy of this system facilitates interpretation of images and might reduce the number of false-positive diagnoses of lesions, such as adenopathy or schwannoma. We hypothesized that this circulation could be visualized on contrast-enhanced, fat-suppressed T1-weighted MR images. METHODS: The craniocervical junctions of 14 patients were scanned using fat-suppressed, contrast-enhanced, T1-weighted MR sequences and evaluated for visibility of the following venous structures: suboccipital cavernous sinus, vertebral artery venous plexus, anterior and posterior condylar veins, vertebral venous plexus, internal jugular vein, and the marginal sinus. Both the right and left sides were assessed in at least two planes. The venous diameters were also measured. RESULTS: All the evaluated venous structures were seen routinely in all three planes, with the exception of the posterior condylar vein, known to be variably present, which was seen only one third of the time in the sagittal plane and two thirds of the time in the other planes. The posterior condylar vein also showed the greatest variability in size and symmetry. CONCLUSION: The suboccipital cavernous sinus and most of its associated venous circulation at the skull base are easily identified on contrast-enhanced, fat-suppressed T1-weighted MR images. The posterior condylar vein, known to be variably present, was not well seen in the sagittal plane and displayed the greatest variability in size and symmetry.
Adult↗
Tanycytomas: a newly characterized hypothalamic-suprasellar and ventricular tumor.
We report five cases of tumors occurring in three children and in two adults. The tumors had unusual histomorphology and a mixture of ependymal and piloid-like astrocytic features and a myxoid stroma similar to myxopapillary ependymomas. MR imaging in three of the cases showed aggressive, intensely enhancing partially cystic hypothalamic-suprasellar masses near midline and near the floor of the third ventricle. In the three pediatric cases, the tumor encased the circle of Willis. This newly characterized tumor, the tanycytoma, has neoplastic cells with histomorphologic and ultrastructural characteristics similar to those of the tanycyte.
Adult↗
Unusual cardiac malformations in Holt-Oram syndrome: report of two cases.
The Holt-Oram syndrome is a hereditary disease which associated with upper limbs anomalies and cardiac defects such as secundum type atrial septal defect. Two cases of this syndrome with unusual cardiac findings are reported: One has an unroofing coronary sinus type atrial septal defect and preexcitation syndrome, the other has pentalogy of Fallot.
Abnormalities, Multiple↗
A tether-free, moving actuator total artificial heart.
An electromechanical moving-actuator TAH was developed and implanted for 5 days in a calf experiment. The efficiency and durability were further improved using pendulous motion of the actuator. This new pendulum pump has a circular motion produced by gear mechanisms connected to the motor. It has a height (from valves to housing bottom) of 7 cm and centrally directed inlets and outlets for good fittability. Active filling (-10 mmHg) inside inner blood sacs was produced by the suction effects of the outer sacs attached to a moving actuator. Two acute animal experiments were performed using the pendulum pump with a Coridale sheep (50 kg weight), and a male calf (70 kg weight). A test was made of 30 minutes of tether-free operation of the implanted pendulum pump inside the small chest of the calf. The pump shows the engineering feasibility of the implantable electrical TAH inside a human chest cavity.
Animals↗
Effect of portal venous hepatic by-pass on urinary histamine excretion in the rat.
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Animals↗
The fluid dynamic effect on protein adsorption in left ventricular assist devices.
Plasma protein adsorption onto an artificial surface is strongly influenced by not only the surface characteristics of materials, but also by the fluid dynamics inside the blood pump, and it would influence subsequent platelet adhesion or activation, which plays a major role in the initiation of thrombus formation at the blood-material interface in vivo. In vitro flow visualization of an electrohydraulic LVAD was performed by a video camera (CCD, Hitachi) and an image processor (PC VISION PLUS) with an IBM PC. The electrohydraulic LVADs were implanted in mongrel dogs of approximately 20 kg. The authors sectioned the blood contacted ventricle after animal death according to the level of shear rate. Because analysis of adsorbed protein might be influenced by the size of the ventricle segment, the number of segments was limited to eight per ventricle. Platelet adhesion and its morphology were observed by scanning electron microscopy (SEM). Adsorbed plasma proteins (fibrinogen, albumin, and IgG) on each segment were quantified by enzyme linked immunosorbent assay (ELISA). The specimens were soaked in 2% (wt/vol) SDS/PBS for 2 days and the released protein concentration assessed. A well developed large vortex was observed at the center of the artificial ventricle. Polyurethane blood pumps displayed different degrees of protein adsorption and subsequent platelet adhesion on each segment.
Adsorption↗
Development of a custom designed TAH using rapid prototyping.
The failure of the orthotopic implantation of a totally implantable artificial heart (TAH) was due mainly to anatomic mismatches in the conduits of the conventional TAH system. To overcome this anatomic incompatibility, a custom design and fabrication process was designed using the rapid prototyping (RP) technique. After three dimensional reconstruction of magnetic resonance imaging of the thoracic cavity and vascular remnants of the recipient, study of anatomic fit was done using the reconstructed thoracic model and three dimensional computer aided design (CAD) model. The direction of the inflow and outflow conduits of the blood sac was changed with a Unigraphics CAD. The RP model of the designed chamber was fabricated and examined for anatomic compatibility. Through this approach, the minute directional mismatch of the inflow and outflow conduits was improved. Thus, a new custom designed moving actuator Korean TAH with CAD and RP techniques was developed.
Biomedical Engineering↗