Optical Constants of Two Typical Liquid Crystals 5CB and PCH5 in the THz Frequency Range.

The complex refractive indices of two benchmark nematic liquid crystal,4-4 '-n-pentyl-cyanobiphenyl (5CB) and 4-(trans-4'pentylcyclohexyl)-benzonitrile (PCH5) have been determinedin the frequency range from 0.2 to 0.8 THz. The technique of coherent THztime-domain spectroscopy (THz-TDS) was used. We show that the birefringenceof 5CB is in the range of 0.15 to 0.21, while that of PCH is from 0.01 to0.08. Both liquid crystals exhibit relatively small absorption in thisfrequency range. The large birefringence of 5CB indicates possible applications of liquid-crystal-based devices for modulation and polarizationcontrol of electromagnetic radiation in the THz frequency range.

Pharmacokinetic study of levofloxacin in rat blood and bile by microdialysis and high-performance liquid chromatography.

The aim of this study was to develop a rapid and sensitive method for the simultaneous determination of unbound levofloxacin in rat blood and bile using high-performance liquid chromatography coupled with microdialysis for further pharmacokinetic study. Microdialysis probes were simultaneously inserted into the jugular vein toward the right atrium and the bile duct of male Sprague-Dawley rats for biological fluid sampling after administration of levofloxacin 3 mg/kg through the femoral vein. Levofloxacin and dialysates were separated using a Merck LiChrospher reversed-phase C18 column maintained at ambient temperature. The mobile phase was comprised of acetonitrile-1 mM 1-octanesulfonic acid (40:60, v/v, pH 3.0 adjusted with orthophosphoric acid). The fluorescence response for levofloxacin was observed at excitation and emission wavelengths of 292 and 494 nm, respectively. The detection limit of levofloxacin was 50 ng/ml. Intra-day and inter-day precision and accuracy of levofloxacin measurements fell well within the predefined limits of acceptability. The disposition of levofloxacin in the blood and bile fluid suggests that there was rapid exchange and equilibration between the blood and hepatobiliary systems, and the plasma level of levofloxacin was greater than that of the bile. Thus, levofloxacin undergoes hepatobiliary excretion but might not be related to the P-glycoprotein transport system.

Life-threatening bleeding in a facial fracture.

Life-threatening bleeding in facial fractures is considered rare, and most reports do not recommend a precise treatment guideline. Although various methods have been suggested, they are unpredictable in efficacy and may lead to irreversible shock. To avoid irreversible shock, early detection and correct, effective treatment are mandatory. The authors report a patient who presented with a complex midface fracture after falling on June 23, 1999. Life-threatening oronasal bleeding developed 1 hour after arriving at the emergency room. Initial nasal packing failed to stop the nasal bleeding. After resuscitation, the patient's vital signs were stable but bleeding persisted. Angiography showed diffuse extravasation of contrast medium over the territory of the right internal maxillary artery. Embolization was performed successfully to stop the bleeding. The authors review the literature regarding the incidence, diagnosis, and treatment of life-threatening facial fracture. In the literature, the lack of a precise definition leads to various results by various treatments. The authors have formulated a succinct treatment guideline. They favor angiographic embolization as the first choice of treatment when tight nasal and/or oral packing fails.

Determination of unbound 20(S)-camptothecin in rat bile by on-line microdialysis coupled to microbore liquid chromatography with fluorescence detection.

To evaluate the biliary excretion of unbound camptothecin, a flow-through microdialysis probe was constructed for bile sampling. The shunt linear probe was connected from the bile duct, between the liver side to the duodenum to avoid obstruction of the bile duct or bile salt waste. For automatic analysis of microdialysate, an on-line injector was connected to a microbore high-performance liquid chromatographic column with fluorescence detection. Samples were eluted with a mobile phase containing methanol-100 mM monosodium phosphoric acid (35:65, v/v, pH 2.5, adjusted with orthophosphoric acid). The limit of quantification was 1 ng/ml for camptothecin. Following camptothecin administration (5 mg/kg, i.v.), it was found in the bile microdialysate. It was concluded that the in vivo microdialysis technique yields useful data on the biliary excretion of camptothecin. This method is suitable for additional pharmacokinetic studies in rat bile.

A novel function of emodin: enhancement of the nucleotide excision repair of UV- and cisplatin-induced DNA damage in human cells.

Nucleotide excision repair (NER) is the main pathway by which mammalian cells remove carcinogenic DNA lesions caused by UV light and many other common mutagens. To explore the effect of emodin on NER, its influence on the repair of UV- and cisplatin-induced DNA damage in human fibroblast cells (WI38) was evaluated. Emodin increased unscheduled DNA synthesis (UDS) of UV-treated cells and reduced cisplatin-induced DNA adducts in WI38 in a concentration-dependent manner, indicating that emodin might promote NER capability in cells. The resultant NER complex is a cooperative assembly of XPF, ERCC1, XPA, RPA, and XPG subunits. The gene regulations of the subunits after emodin treatment were determined by reverse transcription-polymerase chain reaction (RT-PCR) using specific primers. Among the subunits, the expression of ERCC1 in WI38 cells was up-regulated significantly after emodin treatment. All other expressions remained essentially unchanged. In addition, calcium influx in WI38 was increased in proportion to the concentration of emodin. Since UV-induced NER is Ca2+ dependent, elevation of calcium influx may be another mechanism by which emodin facilitates DNA repair. In conclusion, emodin can increase the repair of UV- and cisplatin-induced DNA damage in human cells, and elevated ERCC1 gene expression and Ca2+-mediated DNA repair processes may be involved in the repair mechanism of emodin.

Determination of unbound cefmetazole in rat blood by on-line microdialysis and microbore liquid chromatography: a pharmacokinetic study.

A specific and sensitive microbore liquid chromatographic method for the determination of unbound cefmetazole in rat blood was developed. A microdialysis probe was inserted into the jugular vein/right atrium of a Sprague-Dawley rat. Cefmetazole (10 mg/kg, i.v.) was then administered via the femoral vein. Dialysates were automatically injected into a liquid chromatographic system via an on-line injector. Isocratic elution of cefmetazole was achieved by LC-UV within 10 min. Intra- and inter-assay accuracy and precision of the assay were < or = 10%. The detection limit of cefmetazole was 20 ng/ml. Pharmacokinetic analysis of results indicated that unbound cefmetazole levels in rats best fit a biexponential decay model.

Silicone molar block used as a fulcrum in condylar surgery.

The narrowness of the temporomandibular joint (TMJ) can cause difficulty in open reduction and fixation of condylar fracture. The authors designed a silicone block that acts as a fulcrum to create more space around the TMJ. The block is made of high-quality silicone that is firm, elastic, nontoxic, autoclave tolerant, and harmless to dental tissue. This block has been used successfully in facilitating reduction and fixation of condylar fractures in 27 patients, and for releasing spastic muscles during closed reduction in 2 patients with prolonged TMJ dislocation. In edentulous patients, the silicone molar block can be used as a mouth opener to facilitate most intraoral procedures without injury to the gum.

Preparation and pharmacological evaluation of physostigmine-loaded polyisobutylcyanoacrylate nanoparticles in rats.

The nanoparticles of physostigmine were prepared by an emulsion polymerization of polyisobutylcyanoacrylate. The drug content, release and particle size distribution of the nanoparticles were characterized. In vitro drug release profiles displayed a retardation by the nanoparticles in comparison to the aqueous solution. Pharmacological evaluation of physostigmine nanoparticles in vivo were carried out with Sprague-Dawley rats. The endogenous acetylcholine was sampled by on-line microdialysis and determined by a sensitive microbore HPLC/ED system in the striatum of rats. The choline oxidase and catalase immobilized enzyme reactors were used as the pre-column to erase choline. Accordingly, this chromatographic flow sequence could be utilized for the quantitative assay of acetylcholine without interference. The results indicate that the increase of acetylcholine (%) in the rats striatum by the nanoparticle was 2.3 times (AUC) higher than that of aqueous solution.

The rhamnose moiety of solamargine plays a crucial role in triggering cell death by apoptosis.

Solamargine, solasodine and khasianine steroidal alkaloids are utilized to determine the role of carbohydrate moiety in the mechanism of apoptosis. The C3 side chain of solamargine, khasianine and solasodine contains 4'Rha-Glc-Rha2', 4'Rha-Glc and H, respectively. Solamargine possessed potent cytotoxicity to human hepatoma cells, while the cytotoxicity of khasianine was greatly diminished. Nevertheless, only solamargine could induced "sub-G1" of apoptotic feature in flowcytometry. Thus, the 2'Rha moiety of solamargine may play a crucial role in triggering cell death by apoptosis. In addition, the molecular modeling of solamargine indicated that the 2'Rha moiety was adjacent to the rigid steroid structure, and drastically changed the dihedral angle of the glycosidic bond. The regulations of TNFR I and II expression by different carbohydrate moieties were also distinct. It implied that the carbohydrate moieties of steroidal alkaloids might alter the binding specificity to steroid receptors and consequently regulate the gene expression in different manners.

Unusual dental injuries following facial fractures: report of three cases.

We report 3 cases of unusual dental injuries following facial fractures. The first patient sustained intrusion of a maxillary incisor into the nasal cavity following a mandibular fracture. The tooth dislocated into the pharynx and was found lodged in the piriform fossa during surgery. The second patient sustained intrusion of molars into the maxillary sinus following maxillary and mandibular fractures. His treatment was delayed due to life-threatening hemorrhage. The third case involved ingestion of multiple avulsed teeth into the alimentary tract following severe maxillofacial fractures. Although the diagnosis was made more than a week after the injury, the patient did not suffer any complications as a result of the dental avulsion. The aim of this report is to emphasize the possibility of associated dental injuries in patients with facial fractures. The trauma surgeon should be cognizant of the importance of carrying out a thorough intraoral examination during the initial evaluation. Any missing tooth should be considered as possibly displaced into other tissue compartments, and must be routinely searched for with x-rays of the skull, cervical spine, chest, and abdomen. If full intrusion injury is suspected, further diagnostic investigation with facial computed tomography scanning may be worth while.

Step-wise lengthening for delayed repair of avulsion of the flexor pollicis longus.

Repair of late avulsion of the flexor pollicis longus tendon at insertion is a rare but difficult problem. A 52-year-old female labourer presented with a 3-month history of inability to flex her right thumb at the interphalangeal joint. Avulsion of the flexor pollicis longus tendon at its insertion was noted on exploration. Because the tendon had contracted and could not be reinserted directly, a technique of step-wise lengthening was used for reinsertion. Two months after operation, the patient resumed her daily activities and went back to work with satisfactory use of her right thumb. This report highlights the possibility of using a simple technique when there is no other alternative.

Solamargine purified from Solanum incanum Chinese herb triggers gene expression of human TNFR I which may lead to cell apoptosis.

Solamargine possessed a potent cytotoxicity to human hepatocyte (Hep3B) and normal skin fibroblast. The inhibition curves of solamargine to the both cells were essentially overlapped, suggesting a parallel effect for the cell death. To define mechanism of cytotoxicity of solamargine, the changes of morphology and DNA content in cells were studied. A sub-G1 cell stage was drastically increased after 3-h incubation with solamargine. The results evidence that solamargine arises cell death by apoptosis. In addition, the gene expression of TNFR I were up-regulated within 30 min of solamargine treatment. Since TNF Receptor I has been involved in apoptosis, the overexpression of TNF receptor I may be related with the mechanism of cytotoxicity of solamargine. This communication is the first report that a component of Chinese herbs triggers gene expression of human TNFR I which may lead to cell apoptosis.

Determination of dicentrine in rat plasma by high-performance liquid chromatography and its application to pharmacokinetics.

A simple high-performance liquid chromatographic method was developed to study the pharmacokinetics of dicentrine in rat plasma after 10 mg/kg intravenous administration. After addition of an internal standard (coumarin), plasma was deproteinized by acetonitrile for sample clean-up. The drugs were separated on a reversed-phase Nucleosil C18 column (250 x 4 mm I.D., particle size 5 microns) and detected by photodiode-array detection at a wavelength of 308 nm. Acetonitrile-water (35:65, v/v, pH 2.5-2.8, adjusted with orthophosphoric acid) was used as the mobile phase. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve.

Determination of wogonin in rat plasma by liquid chromatography and its pharmacokinetic application.

A high-performance liquid chromatographic method has been developed for the determination of wogonin in the rat plasma. After addition of an internal standard (clomipramine), plasma was deproteinized by acetonitrile and centrifuged for sample clean-up. The supernatant was separated by a reversed-phase column chromatography, identified by a photodiode-array detector, and quantified by ultraviolet detection at a wavelength of 275 nm. Acetonitrile-water-diethylamine (50:50:0.1, v/v/v, pH 3.0 adjusted by orthophosphoric acid) was used as the mobile phase. The method was applied to the pharmacokinetic study of wogonin in rats after a dose of mg/kg by intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration time profile.

Pharmacokinetics of osthole in rat plasma using high-performance liquid chromatography.

A simple high-performance liquid chromatographic method was developed to study the pharmacokinetics of osthole in rat plasma. After addition of an internal standard (paeonol), plasma was deproteinized by acetonitrile for sample clean-up. The drugs were separated on a reversed-phase column and detected by UV absorption at 323 nm. Acetonitrile-water-diethylamine (50:50:0.1, v/v/v) (pH 3.0, adjusted with orthophosphoric acid) was used as the mobile phase. It was applied to the pharmacokinetic study of osthole in rats after a dose of 10 mg kg-1 by intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve.

Determination of acetylcholine by on-line microdialysis coupled with pre- and post-microbore column enzyme reactors with electrochemical detection.

A sensitive procedure consisting of a pre- and post-microbore column reactor sequence of a LC-electrochemical detection system coupled with on-line microdialysis system is described in the present study to measure endogenous acetylcholine concentration in freely moving rats. The pre-column packed, with immobilized choline oxidase and catalase, was used to remove choline, whereas the post-column, packed with immobilized acetylcholine oxidase and choline oxidase, was used to measure acetylcholine selectively. The detection limit of acetylcholine oxidase and choline oxidase, was used to measure acetylcholine selectively. The detection limit of acetylcholine was found to be 5 fmol/microliter (50 fmol/10 microliters). The usefulness of the described methodology was evaluated by examining the change in the striatal acetylcholine concentration of freely moving rats after physostigmine (0.5 mg/kg, s.c.) administration.

Legionnaires' disease: description of an epidemic of pneumonia.

An explosive, common-source outbreak of pneumonia caused by a previously unrecognized bacterium affected primarily persons attending an American Legion convention in Philadelphia in July, 1976. Twenty-nine of 182 cases were fatal. Spread of the bacterium appeared to be air borne. The source of the bacterium was not found, but epidemiologic analysis suggested that exposure may have occurred in the lobby of the headquarters hotel or in the area immediately surrounding the hotel. Person-to-person spread seemed not to have occurred. Many hotel employees appeared to be immune, suggesting that the agent may have been present in the vicinity, perhaps intermittently, for two or more years.

Legionnaires' disease: isolation of a bacterium and demonstration of its role in other respiratory disease.

To identify the etiologic agent of Legionnaire's disease, we examined patients' serum and tissue specimens in a search for toxins, bacteria, fungi, chlamydiae, rickettsiae and viruses. From the lungs of four of six patients we isolated a gram-negative, non-acid-fast bacillus in guinea pigs. The bacillus could be transferred to yolk sacs of embryonated eggs. Classification of this organism is incomplete. We used yolk-sac cultures of the bacillus as antigen to survey suspected serum specimens, employing antihuman-globulin fluorescent antibody. When compared to controls, specimens from 101 to 111 patients meeting clinical criteria of Legionnaires' disease showed diagnostic increases in antibody titers. Diagnostic increases were also found in 54 recent sporadic cases of severe pneumonia and, retrospectively, in stored serum from most patients in two other previously unsolved outbreaks of respiratory disease. We conclude that Legionnaires' disease is caused by a gram-negative bacterium that may be responsible for widespread infection.