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Biomedical subjects

C T Chen

Publications and source records attributed to C T Chen.

At least 19 recordsLinked to original sources

Vibrio vulnificus infection complicated by acute respiratory distress syndrome in a child with nephrotic syndrome.

A 9-year-old girl with nephrotic syndrome visited a local hospital after developing fever, chills, and edematous changes and multiple hemorrhagic bullae on both legs over 2 days. Cultures of blood and an aspirate from the bullae yielded Vibrio vulnificus. The patient was transferred to our hospital because of persistent fever, generalized edema, acute renal failure, and disseminated intravascular coagulopathy. We treated this patient as a V. vulnificus infection complicated with necrotizing fasciitis. With minocycline and ceftazidime combination therapy was instituted. Emergency fasciotomy and continuous peritoneal dialysis were performed. The patient developed acute respiratory distress syndrome (ARDS) during the hospitalization, requiring intubation and mechanical ventilation. She eventually died. The histopathological findings showed diffuse alveolar damage with lobular pneumonitis. Hyaline membranes, composed of proteinaceous exudate and cellular debris, covered the alveolar surfaces. Microscopic examinations of lung could not distinguish the effects of cytolysin from other insults to lungs that occur in ARDS. This report highlights the postmortem pathological findings in V. vulnificus infection in a child with nephrotic syndrome complicated by ARDS.

Acute Disease

Nociceptin inhibits rat sympathetic preganglionic neurons in situ and in vitro.

In vitro and in situ experiments were conducted to evaluate the hypothesis that the nonclassical opioid peptide nociceptin acting on sympathetic preganglionic neurons (SPNs) inhibits spinal sympathetic outflow. First, whole cell patch recordings were made from antidromically identified SPNs from immature (12-16 day old) rat spinal cord slices. Nociceptin (0.1, 0.3, and 1 microM) concentration dependently suppressed the excitatory postsynaptic potentials (EPSPs) evoked by focal stimulation and hyperpolarized a population of SPNs; these effects were naloxone insensitive. L-Glutamate-induced depolarizations were not significantly changed by nociceptin. Results from this series of experiments indicate that nociceptin inhibits the activity of SPNs by either a presynaptic or postsynaptic site of action, whereby the peptide reduces, respectively, the amplitude of EPSPs or the excitability of SPNs. Second, intrathecal injection of nociceptin (3, 10, and 30 nmol) to urethan-anesthetized rats dose dependently reduced the mean arterial pressure and heart rate; these effects were not prevented by prior intravenous administration of naloxone (1 mg/kg). Physiological saline given intrathecally was without appreciable effects. These results, together with earlier observations of the detection of nociceptin-immunoreactive nerve fibers and nociceptin receptor immunoreactivity in the rat intermediolateral cell column, raise the possibility that the opioid peptide, which may be released endogenously, reduces spinal sympathetic outflow by depressing the activity of SPNs.

Animals

Pressor effects of orexins injected intracisternally and to rostral ventrolateral medulla of anesthetized rats.

Orexin A and B, two recently isolated hypothalamic peptides, have been reported to increase food consumption upon intracerebroventricular injections in rats. In addition to the hypothalamus, orexin A-immunoreactive fibers have been observed in several areas of the medulla that are associated with cardiovascular functions. The present study was undertaken to evaluate the hypothesis that orexins may influence cardiovascular response by interacting with neurons in the medulla. Intracisternal injections of orexins A (0.0056-7.0 nmol) or B (0.028-0.28 nmol) dose dependently increased mean arterial pressure (MAP) by 4-27 mmHg and heart rate (HR) by 26-80 beats/min in urethan-anesthetized rats, with orexin A being more effective in this regard. MAP and HR were not changed by intravenous injection of orexins at higher concentrations. Microinjection of orexin A (14 pmol/50.6 nl) to the rostral ventrolateral medulla, which was confirmed by histological examination, increased MAP and HR. Our results indicate that, in addition to a role in positive feeding behavior, orexins may enhance cardiovascular response via an action on medullary neurons.

Animals

Analysis of nonylphenol polyethoxycarboxylates and their related metabolites by on-line derivatization and ion-trap gas chromatography-mass spectrometry.

This study presents a modified method to analyze nonylphenol polyethoxycarboxylates (NPEC) and their related metabolites (carboxyalkylphenol ethoxycarboxylates (CNPEC)) in water samples. The method involves extraction of samples by a graphitized carbon black (GCB) cartridge, and direct derivatization in the GC injection-port using a large-volume (10-20 microl) direct sample introduction (DSI) device with tetraalkylammonium (TAA) salts. The analytes are identified and quantitated by ion-trap GC-MS. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for NPEC and their metabolites, to quantitation at 0.1 microg/l in 200 ml of water samples. The retention effect of TAA salts in the injection-port is not detected. In addition, the significant [M-29]+ ions and molecular ions of butylated NPEC and CNPEC residues are observed. Recovery of NP1EC in spiked water samples ranges from 90 to 108%. Moreover, relative standard deviations of replicate analyses ranges from 1 to 9%. However, unsatisfactory on-line derivatization of CNPEC residues is observed. This finding maybe owing to their lesser dissociation with the ion-pair reagent in chloroform.

Detergents

Analysis of linear alkylbenzenesulfonates in water samples by large-volume injection-port derivatization and gas chromatography-mass spectrometry.

This work presents a modified method to analyze linear alkylbenzenesulfonates (LASs) in water samples. The method involves extraction of samples by a graphitized carbon black (GCB) cartridge, and direct derivatization in the GC injection port using a large-volume (10-20 microl) direct sample introduction (DSI) device with tetraalkylammonium (TAA) salts. The analytes were then identified and quantitated by ion-trap GC-MS. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for LAS residues, to quantitation at 0.1 microg/l in 200 ml of water samples. The retention effect of TAA salts in the injection port was not detected. Enhanced selected mass chromatograms of [M-55]+ ions of butylated C10-C13 LASs by electron impact ionization MS allows one to determine LAS residues at trace levels in environmental samples. Recovery of total LASs in spiked variety water samples ranged from 89 to 112% while RSDs ranged from 2 to 13%.

Benzenesulfonates

Hypothalamic orexin A-immunoreactive neurons project to the rat dorsal medulla.

Retrograde tract tracing combined with immunohistochemical techniques were used to identify the origin of orexin A-immunoreactive (OrA-ir) fibers in the rat medulla. One to 5 days following injection of the fluorescent dye Fluorogold into the dorsal medulla, labeled neurons were found in the lateral half of the lateral hypothalamus, paraventricular, perifornical, dorsomedial, dorsal and posterior hypothalamic nuclei. Labeling the same sections with OrA antisera revealed a concentration of OrA-ir neurons in the perifornical and dorsomedial regions of the tuberal hypothalamus. A maximum of 10% of Fluorogold-labeled hypothalamic neurons were OrA-ir and 15% of OrA-ir hypothalamic neurons contained Fluorogold. Our results demonstrate that a fraction of OrA-ir neurons in the tuberal hypothalamus project to areas of the medulla that are involved in autonomic functions.

Animals

Orexin A-like immunoreactivity in the rat brain.

Distribution of orexin-A-like immunoreactivity (ORX-LI) in rat brains was investigated with the use of a rabbit polyclonal antibody against the full length peptide orexin A. Virtually all the ORX-LI cell bodies were observed in the lateral hypothalamus at the level of median eminence. The large majority of ORX-LI neurons appeared spherical or fusiform, 20-30 microm in diameter and issued two to five cell processes with few secondary branchings. Numerous ORX-LI fibers were observed in subregions of the hypothalamus. ORX-LI cell processes were sparsely distributed in the cortex, hippocampus and thalamus. Many varicose ORX-LI cell processes were situated close to the 3rd and lateral ventricles, some of which appeared to be protruding into the lumen. As a corollary, orexin A may be released into the ventricles and interact with neurons in distant targets, in addition to influencing the activity of neurons with which ORX-LI axons make synaptic contacts.

Animals

Comparative study on the ALA photodynamic effects of human glioma and meningioma cells.

BACKGROUND AND OBJECTIVE: The purpose of this study was to compare the differential susceptibility to photodynamic therapy (PDT) mediated damage in human U-105MG glioma cells and CH-157MN meningioma cells in vitro using 5-amino-levulinic acid (ALA) as photosensitizer, and to determine if growth factors would enhance PDT-mediated damage of these cells. STUDY DESIGN/MATERIALS AND METHODS: U-105MG or CH-157MN cells were irradiated with polychromatic light in the presence of ALA. A Xenon lamp (150 W) was used as the light source. For the study on the effect of growth factor on ALA-PDT, cells were cultured in serum free medium for 24 hours. Epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), or platelet derived growth factor BB (PDGF-BB) was added to achieve a final concentration of 50 ng/ml. 30 minutes later, cells were incubated with ALA (100 microg/ml) for 24 hours, washed, and irradiated with light (11 J/cm2). MTT tetrazolium assays were performed 24 hours after light irradiation. RESULTS: The inhibition of metabolic cellular function in U-105MG cells by ALA depended on both light energy density and ALA concentration. The susceptibility to ALA-PDT was profoundly lower for CH-157MN meningioma cells than U-105MG glioma cells. When incubated with ALA (100 microg/ml), U-105MG cells exhibited an LD50 around 8 J/cm2 of light irradiation, whereas that of CH-157MN cells was more than 25 J/cm2. EGF, bFGF, or PDGF-BB did not have any effects on the susceptibility of these two cell lines to ALA-PDT. CONCLUSION: ALA-PDT was more effective in killing U-105MG glioma cells than CH-157MN meningioma cells. The differential susceptibility was likely due to differential accumulation of PpIX in these cells. EGF, bFGF, or PDGF-BB did not have stimulatory or inhibitory effect on the efficiency of ALA-PDT.

Aminolevulinic Acid

Compositional and metabolic changes in damaged cartilage are peak-stress, stress-rate, and loading-duration dependent.

The first objective of this study was to determine if the cumulative effects of impact or smoothly arising compression would damage the matrix of articular cartilage. Canine cartilage explants were subjected to repeated impacts or to smoothly arising compressions of as much as 20 MPa at 0.3 Hz for as long as 120 minutes. An increase in the water content of the loaded core compared with the surrounding ring was considered indicative of matrix damage. The results showed that damage to cartilage required repeated impacts with a peak stress of at least 2.5 MPa and a stress rate of at least 30 MPa/sec for 2 minutes or longer. This suggested that impact damage is cumulative and stress-rate dependent. The second objective was to identify biosynthetic and compositional changes in impact-damaged cartilage over a period of time after loading. Accordingly, canine cartilage explants were subjected to repetitive impacts of 5 MPa at 0.3 Hz for 2, 20, and 120 minutes. The loaded explants were then cultured for as long as 10 days. The increase in water content (1.9-3.8%) in the core region relative to the surrounding ring persisted during the 10-day culture. A significant increase in fibronectin synthesis (22-47%) was found in the core region of impact-damaged cartilage. Proteoglycan synthesis was increased by 41-104%. An increase in denatured collagens (11-70%) in the loaded cores substantiated damage to the collagen network. Denatured collagens stained with COL2-3/4m monoclonal antibody were consistent with the compositional findings and were mainly located near the articular surface and in the deep zone. These changes were consistent with early osteoarthritis and suggested the induction of the initial stages of osteoarthritis in the impact-damaged cartilage.

Animals

In vitro diffusion of lidocaine across endotracheal tube cuffs.

PURPOSE: Lidocaine diffuses across endotracheal tube cuffs, which may serve as a reservoir for local anesthetic to assist in the prevention of ETT-induced cough while emerging from general anesthesia. However, the rate of diffusion is slow. Two techniques, alkalization and warming, may increase the proportion of uncharged drug available for diffusion. The purpose of this study is to determine the effectiveness of warming alkalization or warming with alkalization on diffusion. METHODS: Four preparations of lidocaine 4% were studied. Group (Gr) L-lidocaine (24 degrees C), Gr WL--warmed lidocaine (38 degrees C), Gr AL--alkalized lidocaine (24 degrees C), Gr WAL--warmed, alkalized lidocaine (38 degrees C). Twenty-four Mallinckrodt 8.0 ID (Mallinckrodt Critical Care Division of Mallinckrodt, Inc., Glens Falls, New York) endotracheal tube cuffs were filled with 6 ml of one of the four preparations. They were then placed in a 20 ml water bath at 38 degrees C and samples were drawn from the water bath at intervals for up to 360 min. The lidocaine concentration in each sample was determined by gas chromatography. RESULTS: The highest lidocaine concentration was reached in Gr WAL (410.98 +/- 8.53 micrograms.ml-1) after 300 min and then decreased to 376.18 +/- 4.59 micrograms.ml-1 after 360 min. In Gr AL the highest concentration (235.05 +/- 2.99 micrograms.ml-1) was reached after 360 min. Lidocaine concentrations in Gr L and WL after 360 min were 3.19 +/- 1.16 micrograms.ml-1 and 4.32 +/- 2.02 micrograms.ml-1 respectively. CONCLUSION: Alkalization with or without warming, but not warming alone, promotes lidocaine diffusion from endotracheal tube cuff.

Alkalies

Porous chitosan microsphere for controlling the antigen release of Newcastle disease vaccine: preparation of antigen-adsorbed microsphere and in vitro release.

Porous chitosan microspheres suitable for the delivery of antigen were prepared using a wet phase-inversion method. The pore structure of the chitosan microsphere could be modified by the change of pH value of the coagulation medium, which is the aqueous tripolyphosphate (TPP) solution. High porosity of chitosan microsphere with an open porous structure on its surface was prepared by coagulation in TPP aq. solution of pH 8.9. The porous chitosan microspheres were modified chemically with reagents to introduce three types of functional groups; carboxyl, hydrophobic acyl and quaternary ammonium groups. Antigen of ND vaccine was immobilized into the pores of porous chitosan microspheres and the adsorbed antigen was assayed by the Hemoglobin Aggregation (HA) analytical method. Sustained-release of ND vaccine's antigen could be achieved through an adsorption-desorption release test. The chemical modifications of the porous chitosan microspheres have a strong large influence on the adsorption efficiency or release rates of the antigen investigated. The porous microspheres have a higher adsorption efficiency and the slower release rate of antigen when modified chemically with 3-chloro-2-hydroypropyltrimethylamonium chloride.

Adsorption

Preliminary assessment of extrastriatal dopamine D-2 receptor binding in the rodent and nonhuman primate brains using the high affinity radioligand, 18F-fallypride.

We have identified the value of 18F-fallypride [(S)-N-[(1-allyl-2-pyrrolidinyl)methyl]-5-(3-[18F]fluoropropyl)-2, 3-dimethoxybenzamide], as a dopamine D-2 receptor radiotracer for the study of striatal and extrastriatal receptors. Fallypride exhibits high affinities for D-2 and D-3 subtypes and low affinity for D-4 (3H-spiperone IC50s: D-2 = 0.05 nM [rat striata], D-3 = 0.30 nM [SF9 cell lines, rat recombinant], and D-4 = 240 nM [CHO cell lines, human recombinant]). Biodistribution in the rat brain showed localization of 18F-fallypride in striata and extrastriatal regions such as the frontal cortex, parietal cortex, amygdala, hippocampus, thalamus, and hypothalamus. In vitro autoradiographic studies in sagittal slices of the rat brain showed localization of 18F-fallypride in striatal and several extrastriatal regions, including the medulla. Positron emission tomography (PET) experiments with 18F-fallypride in male rhesus monkeys were carried out in a PET VI scanner. In several PET experiments, apart from the specific binding seen in the striatum, specific binding of 18F-fallypride was also identified in extracellular regions (in a lower brain slice, possibly the thalamus). Specific binding in the extrastriata was, however, significantly lower compared with that observed in the striata of the monkeys (extrastriata/cerebellum = 2, striata/cerebellum = 10). Postmortem analysis of the monkey brain revealed significant 18F-fallypride binding in the striata, whereas binding was also observed in extrastriatal regions such as the thalamus, cortical areas, and brain stem.

Animals

Diagnosis of oral cancer by light-induced autofluorescence spectroscopy using double excitation wavelengths.

A cancer diagnostic algorithm, light-induced autofluorescence spectroscopy using double excitations wavelengths, was employed for distinguishing between cancerous and normal oral mucosa. For emission spectra at the shorter excitation wavelengths (280, 290, and 300 nm), the ratio between the area under 325-335 nm and the area under 465-475 nm was calculated. In the same way, for emission spectra at the longer excitation wavelengths (320, 330, and 340 nm), the ratio between the area under 375-385 nm and the area under 465-475 nm was calculated. Receiver operating characteristic curves were used to evaluate the performance of algorithms using single and the double (by combining shorter and longer) excitation wavelengths. The results showed that better performance, up to sensitivity 81.25%, specificity 93.75%, and positive predictive value 92.86%, could be achieved by using the double excitation wavelengths. The present study can be useful as a basis for further investigation on in vivo autofluorescence measurement and analysis using double excitation wavelength.

Algorithms

Three-dimensional finite element analysis of subdural hematoma.

BACKGROUND: Head motion, an important factor in acute subdural hematoma (ASDH), can be broken down into translational and rotational elements. We used three-dimensional finite element analysis to examine the thresholds of angular and tangential acceleration required to tear bridging veins in humans during head impact. METHODS: The lengths of midsagittal and parasagittal bridging veins were calculated first. To assess the effect of translational and rotational acceleration, the strain of each vein was then computed under three different motions. The threshold of ASDH was expressed in terms of tangential and rotational acceleration. RESULTS: Deformation-angle histories of the midsagittal and parasagittal bridging veins showed that veins that drain forward into the superior sinus at a 130-degree angle incurred the greatest stretch strain during occipital impact. In the midsagittal plane, pure rotation induced greater stretch strain on these veins (14.4%) than pure translation (2.5%) or combined translation and rotation motion (10.4%). A tangential acceleration of 3,912.9 G or an angular acceleration of 71.2 krad/s2 seemed to approximate the threshold for ASDH in the human midsagittal plane, whereas 5,010.9 G and 97.4 krad/s2 approximated the threshold in the parasagittal plane. CONCLUSION: Impact direction and orientation of bridging veins are both important factors in ASDH. Threshold criteria for ASDH can be expressed in terms of tangential and rotational acceleration.

Acceleration

Endoscopically assisted mandibular subcondylar fracture repair.

The endoscope has been widely used in aesthetic surgery in recent years, but rarely has it been used in cases of facial trauma. From July of 1996 to December of 1996, the endoscope was used successfully to assist in the repair of mandibular subcondylar fractures in eight patients (five men and three women). Their ages ranged from 15 to 60 years with an average age of 31 years. Six of the patients had other associated mandibular fractures including angular, parasymphyseal, and contralateral subcondylar fractures. A 4.0-mm, 30-degree telescope was introduced to visualize the fracture site by means of an intraoral incision over the ascending ramus. A miniplate was used to stabilize the fracture site with the help of a percutaneous trocar. Intermaxillary fixation was applied for 3 to 6 days. Functionally, all patients returned to normal range of motion within 8 weeks. A slight deviation to the trauma site was noted on maximal opening in three patients, but this condition returned to normal 3 months after surgery. There was no facial palsy or lip numbness. The benefits of the endoscopic approach include not only the provision of better visualization and precise anatomic alignment of bony segments but also the avoidance of large facial scars and facial nerve injuries.

Adolescent

Endoscopically assisted reconstruction of orbital medial wall fractures.

Traditional surgical approaches to orbital medial wall fractures are either direct extraocular skin incisions or indirect bicoronal flap. However, these methods can leave remarkable orbital scars or scalp alopecia with the possible associated complications. A minimally invasive endoscopic technique with the assistance of a 2.7-mm, 30-degree telescope through a medial transconjunctival incision has been successfully used to reconstruct the orbital medial wall fractures. This technique was applied to four patients who had orbital medial wall fractures. Three patients also had concomitant orbital floor fractures. The other had associated superior orbital fissure syndrome. All patients were presented with limited eye movement, positive forced duction test, horizontal diplopia, and enophthalmos (3 mm to 6 mm) preoperatively. The entrapped periorbital tissues in the ethmoid sinus were completely reduced endoscopically. The bone defect of orbital medial wall was reconstructed with autogenous rib bone grafts under endoscopic control. The patients were followed up for 8 to 16 months with an average of 11 months. Three patients recovered completely without any residual eye symptoms after intervention. Clinically significant residual enophthalmos of 3 mm occurred in the patient with the superior orbital fissure syndrome. His eye movement limitation caused by entrapment of medial rectus muscle was relieved postoperatively. There was no donor-site morbidity or any complications related to the endoscopically assisted procedure. Endoscopically assisted medial transconjunctival approach to the orbital medial wall fractures is an excellent adjunct for the exposure and complete reduction of herniated periorbital tissue and bony reconstruction of the medial orbital wall.

Adult

The blood supply of the reverse temporalis muscle flap: anatomic study and clinical implications.

Although the reverse temporalis muscle flap has been used clinically, the exact vascular connection between the superficial and deep temporal vessels has not been clearly defined. The purpose of this study was to investigate the vascular territory of the reverse temporalis muscle supplied by the superficial temporal vessels. Six cadaver heads were studied using a colored lead oxide injection through the superficial temporal artery. The specimens were examined macroscopically and radiographically. The reverse temporalis muscle flap was then applied to a clinical case presenting with traumatic anterior skull base defect communicating with the nasal cavity. The cadaver specimens demonstrated that the superficial temporal artery formed an average 1.3 +/- 0.2 cm in width of dense vascular zone, which was located within 1.8 cm below the superior temporal line. The dense vascular network further perfused the anterior and posterior deep temporal arteries and the muscular branch of the middle temporal artery to supply the temporalis muscle. The mean perfused area of the temporalis muscle was 83 percent, ranging from 79 to 89 percent, in five cadaver heads. One cadaver revealed only 55 percent of perfused area in the absence of the muscular branch of the middle temporal artery. The consistent area without perfusion was located in the distal third of the posterior portion of the reverse temporalis muscle. In clinical cases, the reverse temporalis muscle flap was used successfully to obliterate the anterior skull base defect without evidence of muscle flap necrosis. The exact blood supply to the distal third of the posterior portion of the reverse temporalis muscle flap needs to be investigated further in vivo. Particular attention was paid to the inclusion of the muscular branch of the middle temporal artery in this flap to augment the blood supply to the temporalis muscle.

Adult

Signaling pathway and pepsinogen secretion in Helicobacter pylori-infected human gastric adenocarcinoma.

Although in vitro studies have suggested that Helicobacter pylori not only attaches to cultured cells but also induces signal transduction events in host cells, the underlying mechanism of H. pylori action has yet to be fully investigated. In the present study, a cytotoxin-positive H. pylori was used to infect and examined for its effect on the stimulation of second messengers in human gastric adenocarcinoma (AGS). Results showed that H. pylori increased cytosolic free calcium concentration [Ca2+]i in host cells in a dose-dependent manner. The increase of [Ca2+]i was due to release from the intracellular Ca2+ store as well as entry to the extracellular Ca2+. H. pylori infection on host cells was also found to induce the generations of inositol phosphates, adenosine 3', 5'-cyclic monophosphate, and guanosine 3',5'-cyclic monophosphate, and to stimulate the secretion of pepsinogen.

Adenocarcinoma