[Chiral separation of racemic 5-(p-hydroxyphenyl)-5-phenylhydantoin by RP-HPLC using eluents containing beta-cyclodextrin]

A chiral RP-HPLC method was developed to assay the 5-(p-hydroxyphenyl)-5-Phenylhydantoin (p-HPPH) enantiomers, the major metabolite of antiepileptic drug phenytoin, in rat hepatic microsomes. A 50 mm FLC-C8 column was used as the analytical column, beta-cyclodextrin (beta-CD) as chiral mobile phase additive and phenobarbital as the internal standard. The detection wavelength was 250 nm. The linear range of p-HPPH enantiomers was 0.5-110 mg/L. The detection limit was 5 ng (S/N = 3). The recoveries of S- and R-p-HPPH were 93.6% +/- 2.8% and 94.7% +/- 1.8% respectively. The RSD within day and between days were less than 2%. The concentration of beta-CD played an important role in separating chiral enantiomers. When the concentration of beta-CD was between 8.8 and 13.2 mmol/L the resolution of p-HPPH enantiomers had the largest value Rs = -1.1. In this work, 8.8 mmol/L beta-CD solution (4 g beta-CD, 6 g urea, and 1.5 g ammonium acetate in 400 mL water) was selected in considering some factors such as column efficiency, solubility of beta-CD etc. Urea can increase the solubility of beta-CD. When urea: beta-CD = 1:1-1.5:1 (g/g), the solubilization of beta-CD was significant. Methanol concentration in mobile phase affected retention time, resolution of p-HPPH enantiomers and solubility of beta-CD.

[Improvement of technigue in restoration of stability of thoracolumbal spine]

A new fixator for spine was designed to restore the stability of spine in improving the treatment of thoraco-lumbar dislocation. This instrument was composed of six nails, two longitudinal connecting rods and two transverse connecting rods. On the surface of the nails, there were furrows engraved, instead of screw thread. It fixed the spine through pedicle of vertebra from the posterior approach. The fixed vertebrae were limited between two vertebrae. From 1989 th 1995, twelve patients with fracture-dislocation of thoraco-lumbar spine were reduced with this instrument. After four years follow-up, it showed that the deformity was corrected and the spine firmly fixed. Compared with Dick's screws, it had the following advantages such as simple manipulation, increased strergth of nails and minimal damage to tissue during operation.

[Prediction of RP-HPLC retention index for hydroxyl-containing compounds and their glucuronides]

The quantitative relationships between the structure of solutes and their chromatographic retention behaviors have been widely studied. A lot of compounds have been investigated, but drug metabolites have not been involved. Determination of glucuronic acid conjugation is the most important route for investigations of metabolism of drug, while the glucuronide samples are rarely obtained. In this paper the glucuronides have been obtained with the method of biosynthesis in vitro. The peaks of glucuronides were identified by several means including diode-array spectrophotometer detection, beta-D-glucuronidase hydrolysis, glucuronide references and chromatogram comparison of the incubation samples at different times. Two systems have been developed to predict retention index in reversed-phase high performance liquid chromatography based on the molecular structure of the analytes and on the behavior of the parent compounds. We observed a good correlation between retention index of hydroxyl-containing compounds of glucuronides and hydrophobility based on Hansh pi value: I=383.4+136.0pi, n=10, r=0.9912. A good correlation between hydroxyl-containing compounds and their glucuronides was also observed: Y=-471.1+1.4430X, n=11, r=0.9600. The errors in this experiment are less than 12%.

Mepyramine inhibits platelet activating factor-induced rabbit platelet aggregation: role of intracellular histamine

AIM

To study the possible role of intracellular histamine (HA) in platelet activating factor (PAF)-induced platelet activation.

METHODS

Washed rabbit platelet suspension was used to test the inhibitory effect of mepyramine (Mep, an H1 receptor antagonist) on PAF-induced platelet aggregation. The thromboxane B2 (TXB2) generation was measured by radioimmunoassay and the intracellular calcium ([Ca2+]i) concentration was determined by the specific fluorescence indicator Fura-2.

RESULTS

Mep > 100 mumol.L-1 generated a concentration-dependent inhibition on PAF-induced aggregation, with an IC50 value of 162 (95% confidence limits: 114-232 mumol.L-1). Cimetidine, an H2 receptor antagonist, even up to 400 mumol.L-1 had no effect on it. Exogenous HA (10 mumol.L-1) and H1 receptor agonist, 2-thiazolylethylamine had no energetic effect. alpha-Fluoromethylhistidine, an inhibitor of histidine decarboxylase, did not inhibit platelet responses. However, in platelets permeabilized with saponin (8-10 mg.L-1), exogenous HA attenuated the inhibitory effect of Mep to about 50% at a concentration of 50 mumol.L-1. Preincubation of platelets with Mep (100 or 200 mumol.L-1) resulted in an inhibition on TXB2 generation and [Ca2+]i elevation induced by PAF.

CONCLUSION

Platelets activated by PAF is associated with an intracellular HA synthesis and release via a common pathway of TXB2 generation and the rise of [Ca2+]i.

Particle Aggregation due to Combined Gravitational and Electrophoretic Motion

The stability and pairwise aggregation rates of small spherical particles in a heterogeneous suspension under the collective effects of gravitational motion and electrophoretic migration are analyzed. The particles are assumed to be non-Brownian, with thin, unpolarized double layers and different zeta potentials. The gravity vector and the electric field are assumed to be oriented in either the same direction or opposite directions. The particle aggregation rates are always enhanced by the presence of an electric field for parallel alignment of the gravitational and electrophoretic velocities. For antiparallel alignment with the magnitude of the gravitational relative velocity exceeding the magnitude of the electrophoretic relative velocity between two widely separated particles, the particle aggregation rates are reduced by the presence of the electric field, and there is a "collision-forbidden" region in parameter space due to stronger hydrodynamic interactions of the particles for gravitational motion than for electrophoretic motion. For antiparallel alignment with the magnitude of the electrophoretic relative velocity exceeding the magnitude of the gravitational relative velocity between two widely separated particles, the particle aggregation rates are enhanced by the presence of the electric field.

Functional domains of the nuclear receptor hepatocyte nuclear factor 4

The hepatocyte nuclear factor 4 (HNF-4) is a member of the nuclear receptor superfamily and participates in the regulation of several genes involved in diverse metabolic pathways and developmental processes. To date, the functional domains of this nuclear receptor have not been identified, and it is not known whether its transcriptional activity is regulated by a ligand or other signals. In this report, we show that HNF-4 contains two transactivation domains, designated AF-1 and AF-2, which activate transcription in a cell type-independent manner. AF-1 consists of the extreme N-terminal 24 amino acids and functions as a constitutive autonomous activator of transcription. This short transactivator belongs to the class of acidic activators, and it is predicted to adopt an amphipathic alpha-helical structure. In contrast, the AF-2 transactivator is complex, spanning the 128-366 region of HNF-4, and it cannot be further dissected without impairing activity. The 360-366 region of HNF-4 contains a motif that is highly conserved among transcriptionally active nuclear receptors, and it is essential for AF-2 activity, but it is not necessary for dimerization and DNA binding of HNF-4. Thus, HNF-4 deletion mutants lacking the 361-465 region bind efficiently to DNA as homo- and heterodimers and behave as dominant negative mutants. Remarkably, the full transactivation potential of AF-2 is inhibited by the region spanning residues 371-465 (region F). The inhibitory effect of region F on the HNF-4 AF-2 activity is a unique feature among members of the nuclear receptor superfamily, and we propose that it defines a distinct regulatory mechanism of transcriptional activation by HNF-4.

Random amplified polymorphic DNA analysis of culture collection strains of Candida species

Random amplified polymorphic DNA (RAPD) profiles, obtained when screening culture collection strains of Candida spp., showed several species to be highly heterogeneous. The RAPD-defined groups were as follows: C. catenulata, two groups among five strains; Debaryomyces hansenii (anamorph C. famata), three groups among five strains; C. sake, three groups among three strains; C. intermedia, two groups among two strains; C. rugosa, two groups among three strains and C. parapsilosis, three groups among four strains. The five strains of Issatchenkia orientalis (anamorph C. krusei) belonged to a single RAPD-defined group. The two strains of the teleomorphic yeast Arxiozyma telluris had distinct RAPD profiles but neither resembled profiles of its anamorph, C. pintolopesii. The two varieties of C. pintolopesii had different RAPD profiles. Researchers are cautioned that organisms with the same name may not be closely related.

Intraoperative use of mitomycin in trabeculectomy

Mitomycin (0.2 mg/ml) was applied intraoperatively to 26 glaucomatous patients (33 eyes) during conventional trabeculectomy procedure. Most of them were considered to be at high risk of surgical failure. The conjunctival flap was fornix-based in 9 patients (11 eyes). The success rate was 84.8% without any serious side effect.

Experimental studies of the effect of Forskolin on the lowering of intraocular pressure

PURPOSE

To determine the effect of domestic Forskolin on lowering of intraocular pressure (IOP) in rabbits.

METHODS

Measure the normal IOP and ocular hypertension by water load in rabbits using Perkins tonometer. Measure the adenylate cyclase (AC) activity by Ho & Sutherland's method.

RESULTS

The results show that Forskolin significantly lowered the normal IOP of rabbits and blocked the ocular hypertension induced by water load in rabbits (P < 0.01). The maximum decrease value of 2%, 1% and 0.5% of the Forskolin was 0.59, 0.36 and 0.19 kPa (1kPa = 7.5 mmHg), which showed the noticeable dose-effect relationship. Topical ocular application of Forskolin lowered IOP in half an hour, reached to a peak in 2-3 hours and remained significantly for 10 hours. The pupillary diameter did not change when IOP was reduced. The Forskolin had potent stimulative properties to AC. The greater the ability of the Forskolin to stimulate AC, the stronger the effect of IOP lowering.

CONCLUSIONS

The Forskolin had the effect on lowering the IOP of rabbits. The mechanism of IOP reduction by Forskolin is related to its AC activation.

[An experimental study on homoharringtonine and glaucoma surgery]

PURPOSE

To test the inhibiting effect of a Chinese herbal drug. Homoharringtonine (HH) on the wound healing process at the filtering site in an experimental model.

METHODS

Posterior sclerectomies were performed in 20 rabbits. Postoperatively one eye of each rabbit received subconjunctival injections of HH and fellow eye received saline injections in a randomized masked fashion.

RESULTS

14 days after operation, intraocular pressure decreased significantly compared with that of control (P < 0.05). The number of filtration blebs was greater than that of control (14/6). On pathological examination, the number of fibroblasts per square measure of cross section of tissue cut from filtration region that was diminished significantly compared with that of control (P < 0.01). There were no serious and permanent ocular toxic and side effects.

CONCLUSIONS

The study suggests that the HH can inhibit cicatrization at the glaucoma filtering site, promote the formation of filtering blebs and provide a sufficient evidence for the further clinical use of HH.

The Resistance of the Diffusion Barrier in Nodules of Myrica gale L. Changes in Response to Temperature but Not to Partial Pressure of O2

Rates of C2H2 reduction and CO2 evolution by nodules were measured in a flowthrough system using intact plants of Myrica gale L. Both activities increased linearly with increasing partial pressure of O2 (pO2) up to 18 kPa. The linear relationship between CO2 evolution and pO2 at pO2 values between 6 and 18 kPa suggests that the diffusion barrier has a constant resistance. The lack of a variable resistance was further supported by sustained increases and decreases in nodule activities in response to changes in pO2 in the range of 6 to 20 kPa O2. When pO2 was increased above 20 kPa, C2H2 reduction and CO2 evolution continually declined with time. These results confirm that the diffusion barrier in nodules of M. gale is not variable in response to changes in pO2. The effect of temperature was examined at 8 and 20 kPa O2. Rates of C2H2 reduction and CO2 evolution increased with increasing temperature from 10 to 30[deg]C at both pO2 values. These results indicate that the diffusion resistance of the barrier changes as temperature changes, with the resistance decreasing as temperature increases.

[Functional analysis of the CPS I upstream sequences with a CAT assay]

Expression plasmids (pKCPSx-CAT) containing carbamyl phosphate synthetase I (CPS I) upstream sequences of different lengths were constructed, and the function and characteristics of the sequences were studied with the CAT assay. The results showed that the CPS I upstream sequences exerted highly tissue-specific control on CPS I gene expression, and the -142- -38bp region relative to the cap site was found to be indispensable for CPS I gene transcription. The -1700- -161bp region contains sequences which confer an enhancing effect on CPS I gene transcription. Dexamethasone and thioproline (a differentiation inducer) showed enhancing effects on CPS I gene transcription in hepatoma cells. These results would have significance in studies on the gene regulation of CPS I associated with the mechanism of hepatocyte differentiation and carcinogenesis.

Intravitreal pharmacokinetics of liposome-encapsulated amikacin in a rabbit model

BACKGROUND

Intravitreal injection of antibiotics has become a standard therapy for bacterial endophthalmitis. The duration of effective antimicrobial levels in the vitreous after single injection, however, may not be long enough to get optimal response. The authors prepared liposome-encapsulated amikacin for prolonging the duration of intravitreal therapeutic concentrations and investigated the intravitreal pharmacokinetics of the liposomes and amikacin in phosphate buffer solution (PBS) as control.

METHODS

The liposome-encapsulated amikacin was prepared by reverse-phase evaporation method. The intravitreal pharmacokinetics of the liposomes was compared with amikacin in PBS by fluorescence polarization immunoassay. Albino rabbits were randomly distributed into 12 groups. Rabbits in groups 1 to 6 and in groups I to VI (control groups) received an intravitreal injection of the liposome-encapsulated amikacin and amikacin in PBS, respectively.

RESULTS

The encapsulation rate of amikacin was 91%. The time of 50% spontaneous degradation (half-life) of the liposomes in PBS (38 degrees C, pH 7.4) was 47.6 days, and the time of 50% release (half-life) of the drug from the liposomes in PBS was 84.8 hours. The vitreous amikacin concentrations in groups 1 to 6 were significantly greater (P < 0.05) than those in control groups I to VI in every time interval, except in groups 1 to 3 at 1 hour after injection. The difference was particularly obvious in the endophthalmitis groups. The clearance of encapsulated amikacin in vitreous appeared to be related to the state of blood-ocular barrier and to the structural integrity of vitreous. The distribution, the absorption, and the elimination of encapsulated amikacin in vitreous showed the first-order kinetics.

CONCLUSION

The liposome-encapsulated amikacin prolonged half-life of the drug in vitreous. The results of the pharmacokinetic analysis suggested that in endophthalmitis, especially in severe cases, the liposomes may be preferable to conventional preparation.

Comparative investigation of disposition of 3,4-(methylenedioxy)methamphetamine (MDMA) in the rat and the mouse by a capillary gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization

A gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization has been developed for MDMA and three of its primary metabolites in biological specimens; the assay is linear from 2 to 1000 ng ml-1. Quantitatively, more of an administered dose of 10 mg kg-1 MDMA was excreted by the mouse (72%) than by the rat (35%); most in both species was excreted in urine and within 24 h. The difference in per cent excretion is entirely due to proportionally greater excretion of the parent drug by the mouse. 4-Hydroxy-3-methoxymethamphetamine (HMM) is the major urinary metabolite in both species. HMM and another primary metabolite, 4-hydroxy-3-methoxyamphetamine (HMA), were excreted mainly as glucuronide and sulphate conjugates (> 85%).

[The experimental studies of the effect of Forskolin on the lowering of intraocular pressure]

The effect of the domestic Forskolin on lowering the intraocular pressure (IOP) of rabbits was studied. The results showed that the Forskolin significantly lowered the normal IOP of rabbits and blocked the ocular hypertension induced by water load in rabbits (p < 0.01). The maximum decrease value of 2%, 1% and 0.5% of the Forskolin was 0.59. 0.36 and 0.19 kPa (1 kPa = 7.5 mmHg), which showed the noticeable dose-effect relationship. Topical ocular application of Forskolin lowered IOP in 1/2 hour, reached to a peak in 2-3 hours and remained significantly for 10 hours. The pupillary diameter did not change when IOP were reduced. Furthermore, the Forskolin had potent stimulative properties to adenylate cyclase (AC). The greater the ability of the Forskolin to stimulate AC, the stronger the effect of IOP lowering.

Clinical value of lung scintigraphy with Tc-99m gluconate in distinguishing benign from malignant lung diseases

One hundred patients were studied with three-phase lung scintigraphy with Tc-99m gluconate. The results showed that there were statistically significant differences between benign and malignant lung lesions in the intensity of accumulation, the blood supply index ratio, and the radioactive uptake ratio. However, no difference was observed between the benign lung lesions and the healthy lungs. Analysis of false negatives and false positives revealed that false negatives had something to do with the cell types of the malignancies, in addition to the relatively small size of the lesions; the false positives were mostly caused by acute inflammation, for which obstructive pneumonitis might be responsible in part. It is concluded that Tc-99m gluconate is tumor-avid and can be used as an agent for positive imaging of lung cancer, because quantitative parameters, blood supply index ratio, and radioactive uptake ratio are more objective in distinguishing malignant lung lesions from benign ones, and are of relatively higher sensitivity and specificity. Thus, lung scintigraphy with Tc-99m gluconate provides an efficient supplementary measure for differentiating between malignant and benign lung lesions.

Metabolism of carotenoid analogs in humans

Single oral doses (100 mumol) in peanut oil of 4,4'-dimethoxy-beta-carotene, ethyl beta-apo-8'-carotenoate, and beta-apo-8'-carotenal were administered to healthy adult male subjects (n = 4-6). Blood samples were taken frequently thereafter, and serum carotenoids and retinoids were analyzed by HPLC. The metabolism of the three analogs was very different; 4,4'-dimethoxy-beta-carotene was oxidized at the 4 and 4' positions but apparently not cleaved, whereas ethyl beta-apo-8'-carotenoate was not detectably metabolized, and beta-apo-8'-carotenal was extensively converted to its corresponding acid, alcohol, and fatty acyl ester and detectably converted to retinyl ester and possibly to two shorter beta-apocarotenals. Serum concentrations of endogenous retinoids and carotenoids, except as noted above, were not affected in any case. Kinetically, the maximum serum concentrations, areas under the curve, and mean sojourn times for the three analogs differed by 50-, 270-, and 5-fold, respectively. For any given analog, however, the fractional standard deviations for these parameters were only 0.2-0.5.

Functional analysis of the CPS I upstream sequences with a cat assay

Expression plasmids (pKCPS-CAT) containing carbamyl phosphate synthetase (CPS I) upstream sequences of different lengths were constructed, and the function and characteristics of the sequences were studied with the CAT assay. Results showed that the CPS I upstream sequences exerted highly tissue-specific control on CPS I gene expression, and the -113 approximately -38 bp region relative to the cap site was found to be indispensable for CPS I gene transcription. The -1700 approximately -161 bp region contains sequences which confer an enhancing effect on CPS I gene transcription. Dexamethasone and thioproline (a differentiation inducer) showed enhancing effects on CPS I gene transcription in hepatoma cells. These results would have significance in studies on the gene regulation of CPS I associated with the mechanism of hepatocyte differentiation and carcinogenesis.

A survey of children with HBsAg markers related to their parents HBV markers

It was showed that 103 children with HBsAg markers alone (4-8 years of age) were closely selected to their either mothers or fathers. The data indicated that all of HBV markers were detected in all samples except. Three of them. But one of their three children was adopted. The ratio of HBsAg and HBeAg in the parent's positive sera was 26.6% to 12.5%. Even though the mother with HBeAg marker played an important role in the transmission of hepatitis B infection, but we could not omitted the role of father with HBeAg marker. Therefore some persistent appropriate measures in daily life was necessary to prevent children from HBV infection. Hepatitis B vaccine inoculation should be considered firstly on new born infants, nursery children and then those who were HBV markers negative.

Menstrual blood loss and hematologic indices in healthy Chinese women

Menstrual blood loss, cyanmethemoglobin and serum ferritin were determined in 421 healthy, noncontracepting Chinese women. The range of menstrual blood loss (MBL) was 4.1-273.6 mL, the mean value was 54.2 mL, and the median was 42.9 mL. The range of hemoglobin was 8.3-16.7 g/dL, and the mean value was 13.2 g/dL. The range of ferritin was 1.2-180.0 ng/mL, the mean value was 22.8 ng/mL, and the geometric mean was 17.1 ng/mL. The upper normal limit of MBL in Chinese women was set at 80 mL.

Menstrual blood loss, haemoglobin and ferritin concentration of Beijing women wearing steel ring, VCu 200, and TCu 220c IUDs

Menstrual blood loss (MBL), serum ferritin and whole blood cyanmethemoglobin were measured at pre- and 1, 3, 6, 12, 18 and 24th postinsertion cycles in 60 women wearing the Steel Ring, the Copper V (VCu 200) or the Copper T (TCu 220c). The MBL, incidence of menorrhagia and iron deficiency anemia were lower among users of the Steel Ring than among users of the Copper V and T. Anemia occurred later and the duration of menstruation was shorter with the Steel Ring than with the Copper T. There were no statistically significant differences between the Copper V and T.