[Determination of morphine in compound liquorice tablets by high performance liquid chromatography with SEP-PAK C18 cartridge pretreatment]

An efficient method combining SEP-PAK C18 cartridge solid phase extraction (SPE) with reversed-phase high performance liquid chromatography for the quantitation of morphine in the Compound Liquorice Tablet is presented. The tablets have been used for making expectoration easy and relieving cough for years. The tablet powder (approximately 1 tablet) was added into a stoppered centrifuge tube, and vertically extracted with 5 mL of 0.5% HAc for 5 min. After centrifugation the supernatant was transferred to a beaker and the extraction was repeated twice with 4 mL and then 3 mL of 0.5% HAc. Five millilitres of carbonate buffer (pH 8.9) was added to the combined extracts. A SEP-PAK C18 cartridge was pretreated by passing methanol and distilled water, using a glass syringe. The mixture was applied on it and allowed to flow through. The cartridge was washed first with 5 mL of 10% methanol solution and then the morphine was eluted with 4 mL of 70% methanol solution into a 5 mL volumetric flask and was finally diluted to volume with 70% methanol solution. Analysis was performed on a mu-Bondapak C18 column(300 mm x 4.6 mm i.d., 10 microns) with 0.1 mol/L NaH2PO4-methanol(5:1) as the mobile phase and detection at 286 nm. The average recovery of morphine was (101.2 +/- 1.5)% and RSD was 1.5%. The method is simple, rapid, accurate, and reproducible, and can be used in drug control.

Conformation of the Ras-binding domain of Raf studied by molecular dynamics and free energy simulations

Recognition of Ras by its downstream target Raf is mediated by a Ras-recognition region in the Ras-binding domain (RBD) of Raf. Residues 78-89 in this region occupy two different conformations in the ensemble of NMR solution structures of the RBD: a fully alpha-helical one, and one where 87-90 form a type IV beta-turn. Molecular dynamics simulations of the RBD in solution were performed to explore the stability of these and other possible conformations of both the wild-type RBD and the R89K mutant, which does not bind Ras. The simulations sample a fully helical conformation for residues 78-89 similar to the NMR helical structures, a conformation where 85-89 form a 3(10)-helical turn, and a conformation where 87-90 form a type I beta-turn, whose free energies are all within 0.3 kcal/mol of each other. NOE patterns and H(alpha) chemical shifts from the simulations are in reasonable agreement with experiment. The NMR turn structure is calculated to be 3 kcal/mol higher than the three above conformations. In a simulation with the same implicit solvent model used in the NMR structure generation, the turn conformation relaxes into the fully helical conformation, illustrating possible structural artifacts introduced by the implicit solvent model. With the Raf R89K mutant, simulations sample a fully helical and a turn conformation, the turn being 0.9 kcal/mol more stable. Thus, the mutation affects the population of RBD conformations, and this is expected to affect Ras binding. For example, if the fully helical conformation of residues 78-89 is required for binding, its free energy increase in R89K will increase the binding free energy by about 0.6 kcal/mol.

Ontogeny of basolateral membrane sodium-hydrogen exchange (NHE) activity and mRNA expression of NHE-1 and NHE-4 in rat kidney and jejunum

Na+/H+ exchange (NHE) activity varies with ontogenic state in rat intestinal basolateral membrane vesicles (BLMV). The current investigation sought to determine if these observations are due to differential expression of BLM NHE isoforms, NHE-1 and NHE-4. In rat kidney, BLMV sodium uptake levels were similar in 2, 3 and 6 week rats (13.28+/-0.68, 14.03+/-0.84, and 11.71+/-0.66 nmol Na+/mg protein/30 s, respectively), and lower in adults (5.53+/-0.24) (n=4; p<0.001 between 2 week rats and adults, and between 3 week rats and adults; p<0.01 between 6 week rats and adults). In rat jejunum, BLMV uptake was highest in adults (13.07+/-0.86 nmol Na+/mg protein/30 s), and decreased in 6, 3, and 2 week rats (4.48+/-0.75, 2.94+/-0.68, and 1.59+/-0.58, respectively) (n=4; p<0.001 between all groups and adults). Control immunoblot experiments with NHE-3 antiserum showed that BLMV preps were not contaminated with significant amounts of this brush-border membrane specific protein. Northern blots with isoform-specific probes showed highest renal NHE-1 hybridization intensities in 2 and 3 week rats (11.00+/-0.25 and 12.07+/-0.16 phosphorimage units, respectively), and lower intensities in 6 week and adult animals (4.30+/-0.95, and 4.40+/-1.40, respectively) (n=4; p<0.01 between 2 week animals and 6 week and adult animals, and between 3 week animals and 6 week and adult animals). NHE-1 probes in the intestine showed no hybridization intensity differences between groups: 2 week-7.09+/-1.10, 3 week-5.39+/-0.56, 6 week-8. 24+/-1.57, and adult-8.99+/-2.20 (n=3). NHE-4 specific probes in the kidney showed hybridization intensity levels of 9.22+/-0.35 in 2 week animals, 12.12+/-1.26 in 3 week animals, 5.63+/-0.81 in 6 week animals, and 3.52+/-0.57 in adults (n=4; p<0.05 between 2 week and adults; p<0.01 between 3 week and 6 week animals, and between 3 week and adults). No NHE-4 message was detected in rat jejunum by Northern blot analysis or by reverse transcriptase-PCR. These results suggest that ontogenic NHE activity at the jejunal BLM is not related to differential expression of NHE-1, while NHE activity at the renal BLM may in part be related to differential ontogenic expression of NHE-1 and NHE-4.

Functional and molecular characterization of NHE3 expression during ontogeny in rat jejunal epithelium

Ontogenic changes occur in intestinal brush-border membrane vesicle (BBMV) Na+/H+ exchange activity. The present studies were designed to investigate ontogenic changes in Na+/H+ exchanger (NHE) isoform 3 in rat jejunum. pH-dependent Na+ uptake was assayed in four age groups of rats in the presence of 0, 50, or 800 microM HOE-694, a specific NHE inhibitor with differential sensitivities for NHE2 [inhibition constant (Ki) = 5 microM in PS120 fibroblasts] and NHE3 (Ki = 650 microM). Results showed that NHE2 and NHE3 contribute to basal BBMV uptake at all ages. Uptake levels were highest in 6-wk-old rats, lower in adult rats, and lowest in 2-wk-old (suckling) and 3-wk-old (weanling) rats, NHE3 contribution ranged from 92% at 6 wk of age to 59% at 2 and 3 wk of age. NHE3 inhibition by 800 microM HOE-694 was 38-45%. Statistical analysis showed that HOE-694 had a significant effect at both concentrations at all ages and that differences were present between all ages except 2- and 3-wk rats (at all HOE-694 concentrations). Northern blot analyses of jejunal mucosa showed lowest NHE3 mRNA levels in 2-wk animals and higher levels in all other age groups. Polyclonal antibodies were developed against an NHE3 COOH-terminal fusion protein, and antiserum was characterized with NHE3-transfected PS120 cells and by immunohistochemistry. Western blot analyses showed lowest protein levels in 2-wk animals and higher levels in the other ages. Suckling rats were subcutaneously injected with methylprednisone (MP) for 2 days and killed 1 day later. Northern blot analyses showed a twofold increase in NHE3 mRNA expression with MP treatment. Immunoblot analyses showed a 2.5-fold increase in NHE3 immunoreactive protein levels with MP injection. Overall, these data suggest that NHE3 is regulated during ontogeny and that ontogenic changes are most apparent around the time of weaning. Furthermore, the data suggest that NHE3 is regulated at transcriptional and posttranscriptional levels during mammalian intestinal development.

Whole body leptin kinetics and renal metabolism in vivo

Leptin metabolism was investigated in male Sprague-Dawley rats by use of 125I-labeled leptin plasma kinetic and arteriovenous balance studies. When conscious rats received bolus venous injections of 125I-leptin, intact (precipitable) leptin quickly disappeared from circulation in a biexponential manner during the 2-h experimental period. After substantial delay, most of the injected radioactivity appeared in the urine. The data were described by a two-compartment model, which postulated that plasma leptin exchanged with a nonplasma pool and that all of the tracer cleared from plasma appeared in urine or in a degraded form in plasma. The half-life of leptin was 9.4 +/- 3.0 min, and the leptin production rate was 3.6 +/- 1.2 ng 100 g fat-1.min-1. The left kidney extracted 21 +/- 1.5% of intact arterial 125I-leptin 5 min after femoral venous injection. Endogenous arterial leptin was reduced 21 +/- 8 and 18 +/- 12%, respectively, in simultaneously sampled left and right renal veins. Renal elimination appears to be the major elimination mechanism for leptin in normal rats, and the kinetic studies suggest that uptake of leptin by renal tissue rather than glomerular filtration is the predominant elimination mechanism.

[Measurement and clinical significance of inspiratory drive efficacy in patients with chronic obstructive pulmonary disease]

To study the relationship between VT/P0.1 and the function of inspiratory muscles, we performed the measurement of VT/P0.1 (inspiratory drive efficacy), MIP (maximal inspiratory mouth pressure) and MMIF (maximal midinspiratory flow) in 15 normal subjects and 60 patients with chronic obstructive pulmonary disease(COPD). The results indicated that VT/P0.1 decreased with the deterioration of COPD and it correlated highly and positively with MIP and MMIF. These suggest that VT/P0.1 can reflect the function of inspiratory muscles as well as MIP and MMIF can.

[Determination of plasma drug concentration and bioavailability of indomethacin controlled release capsule by high performance liquid chromatography]

A simple, rapid, sensitive and accurate reversed-phase high performance liquid chromatographic (RP-HPLC) method for the determination of indomethacin in plasma is established. To 1 mL of plasma were added 200 microL of amobarbitone solution (internal standard; 1 g/L), 100 microL of phosphate buffer solution (pH 7.0), 100-150 mg of sodium chloride and 2.5 mL of ethyl acetate. The mixture was vortex-mixed for 10 min and centrifuged at 3000 r/min for 5 min. The organic layer was evaporated to dryness at 50 degrees C on water-bath and the residue was dissolved in methanol (100 microL). A 20 microL portion of the resulting solution was analysed by HPLC on a column (25 cm x 4.6 mm) of micro-Bondapak C18 (10 microm) with 76% methanol in 0.035 mol/L phosphoric acid (pH 5.5) aq-solution as mobile phase (1 mL/min) and UV detection at 260 nm. The column temperature was 30 degrees C. Within the range of 0.125-50 mg/L of indomethacin there was a good linearity (r = 0.9996). The mean recovery of indomethacin was 100.4%. The detectable limit was 62.5 microg/L (S/N = 3:1). The within day and day-to-day RSD were less than 5% at three drug levels. This method has been used to determine plasma drug concentration and bioavailability of indomethacin controlled release capsule for healthy volunteers.

Differences in molar absorptivity of 4-NP with the reaction solution and apparatus affect ALP measurement

We examined the differences in molar absorptivity of 4-NP obtained using different kits for ALP measurement and different instruments. The apparent molar absorptivity of 4-NP in the same reaction solution determined by six different instruments was 15.98, 16.72, 16.06, 17.00, 16.27, 17.62 and that using four different reaction solution kits for ALP with the same instrument was 16.90, 17.38, 17.72, 16.11. We measured ALP in three serum samples with six instruments using the same kit and in twelve serum samples with the same instrument using four kits. ALP activities measured using the same molar absorptivity value differed with the instrument(p < 0.01). However, those measured using the apparent molar absorptivity value for each instrument revealed no significant differences(p > 0.05). In conclusion, we suggest that standard material should be contained in each kit for enzyme measurement and the apparent epsilon for each kit and instrument should be obtained to minimize the systematic error caused by using the same epsilon in different laboratories.

Calcium ATPase activity and membrane structure in clear and cataractous human lenses

PURPOSE

Maintenance of calcium homeostasis is imperative for the clarity of the lens. Ca(2+)-ATPase is essential for the removal of cytosolic calcium, either across the plasma membrane or through intracellular organelles such as the endoplasmic reticulum. In this study, membranes prepared from clear lens epithelium were compared to membranes prepared from cataractous lens epithelium.

METHODS

Human lens membranes were prepared by a protocol utilizing homogenization and centrifugation. Ca(2+)-ATPase activity was measured biochemically using Gamma-32P labeled ATP. Lipid order was measured using infrared and Raman spectroscopy.

RESULTS

Ca(2+)-ATPase activity was similar in membranes prepared from cataractous lenses that were classified as nuclear subcapsular, nuclear and brunescent cataracts. Ca(2+)-ATPase activity was approximately 50% less in membranes prepared from cataractous lenses in comparison to clear lenses. Because clear lenses from Indian donors was unavailable, clear human lenses were used as a qualitative control for the measurement for Ca(2+)-ATPase activity. Lipid order was measured in lens fibers from cataractous and clear lenses from the United States donors. Lipid order increased from 55% in the hydrocarbon chains from clear lens fibers to 84% in cataractous lens fibers.

CONCLUSIONS

These findings support the hypothesis that membranes are deranged in cataractous tissue, which should lead to altered levels of calcium.

[Effect of methylphenidatum on inspiratory muscles function in patients with chronic obstructive pulmonary disease and its mechanism]

To have a better understanding of the effect of methylphenidatum on inspiratory muscles function, we studied the respiratory force parameters of 70 patients with chronic obstructive pulmonary disease by intravenous infusion methylphenidatum in a randomized controlled clinical trial. The indices of respiratory force parameter included maximal inspiratory mouth pressure (MIP), maximal midinspiratory flow (MMIF), forced inspiratory capacity (FIC), maximal works of inspiration (Wimax) and airway occlusion pressure (P0.1), etc. Aminophylline and Nikethamidi were chosen as controls. The results showed that MIP, MMIF, FIC, Wimax, P0.1 and minute ventilation (Vr) were significantly increased after administration of methylphenidatum and aminophylline. There were no significant differences in MIP, MMIF, FIC and Wimax after administration of Nikethamidi, but P0.1 was significantly increased and the increase was higher than that after administration of methylphenidatum and aminophylline groups. We conclude that methylphenidatum can significantly improve the function of inspiratory muscles as aminophylline can do.

Histopathologic and biochemical changes in the muscles affected by distraction osteogenesis of the mandible

Lengthening of the canine mandible using an intraoral distraction device was performed in order to study the effects of distraction on the associated muscles of mastication. Biopsies of the masseter and digastric muscles were taken after lengthening at four different time intervals to assess the temporal changes in the masticatory muscles of 10 dogs. Biopsies of the muscles on the contralateral side also were taken from 6 of these dogs before lengthening to establish a control group. Each biopsy was analyzed histologically and spectophotomerically for RNA, DNA and protein content. The digastric muscle underwent transient atrophy with initiation of distraction but regenerated completely after 48 days of fixation. The masseter muscle was unchanged initially but showed evidence of atrophy only after 20 mm of distraction it continued to exhibit evidence of atrophy during fixation. Protein synthesis was decreased significantly during periods of atrophy in the masseter; no such change was noted in the digastric. Unlike the masseter, the digastric fibers lie in a plane parallel to the vector of distraction. These findings suggest that any muscle affected by skeletal distraction in the same plane or vector (e.g., digastric) adapts with compensatory regeneration and hypertrophy. Moreover, those muscles lying in a different plane (e.g., masseter) show persistent evidence of atrophy with decreased protein synthesis.

Calcium permeability in large unilamellar vesicles prepared from bovine lens cortical lipids

The loss of calcium homeostasis in the lens is thought to play an important role in cataract formation. Although both lens Ca(2+)-ATPase and membrane lipid permeability are essential to calcium homeostasis, membrane permeability has been studied less extensively. In the present study, the calcium permeability of large unilamellar vesicles (LUVs) prepared from bovine lens cortical lipids has been characterized. When a calcium gradient had been established by the addition of CaCl2 to the external medium, calcium influx through the membrane was monitored by calcium concentration sensitive changes in Fura-2 fluorescence as a function of time. The calcium permeability coefficient, P, was 4.46 x 10(-13) cm s-1 at 37 degrees C. This value was about 4 fold higher than that for LUVs prepared from egg phosphatidylcholine and many times higher than that for LUVs prepared from sphingomyelin. These results provide a basis for future studies of factors that influence the permeability of lens cell membranes to calcium.

[Cetirizine improves the resistance of airway and pulmonary function in patients with asthma]

The objective of this study was to investigate the possible anti-asthma role of Cetirizine. Forty asthmatics were randomly divided into two groups. The experimental group had 30 patients. Among them were 10 patients with simple asthma, 5 patients complicated by mild emphysema, 6 patients complicated by moderate emphysema and 9 patients complicated by severe emphysema. Vit-C (control) group had 10 cases, including 2 cases of simple asthma, 6 cases complicated by mild emphysema and 2 cases complicated by moderate emphysema. All patients had a single oral dose of 5 mg Cetirizine or 0.1 g Vit-C blindly. Before and 0.5, 1 hour after their medicines, the resistance of airway (Raw), sGaw and MEFV were examined in all patients on 6200 Plethysmograph. The measured values showed a significant improvement of Raw and sGaw after administration of Cetirizine. In half an hour after Cetirizine, the Raw decreased by 20.408%, and sGaw increased by 28.249%. In one hour after Cetirizine, Raw further decreased by 24.34% and sGaw increased by 41.153% (P < 0.001). The FVC in MEFV increased by 4.96% (P < 0.02) in one hour after Cetirizine, but other parameters in MEFV curve (PEF, FEV1, MMEF) had no significant changes. All parameters in control group had no significant changes (P > 0.05). The results indicate that Cetirizine could decrease Raw in asthmatics, improve their lung ventilatory function. Cetirizine is a new H-receptor antagonist usually used as anti-inflammatory and allergy suppression medication. It is shown that Cetirizine is a promising anti-asthma agent in treating bronchial asthma.

[The combined subdermal vascular network skin flaps of the abdominal wall for the repair of soft tissue defects on the dorsum of hand]

Successful reconstructive surgery was performed on ten patients with skin and soft tissue defects on the dorsum of their hand and fingers using combined subdermal vascular network flaps of the abdominal wall. The pedicle of the flap was divided on 7-10 postoperative day when wound was closed, finger and web reconstruction were completed at the same stage. The operative results were satisfactory. The authors discussed the technique of the method, the blood supply of the flap, the principle of the design and the advantages of the operation.

[Value of measuring resistance of airway for diagnosis of asthma]

Resistance of airway (Raw), sGaw and Maximal expiratory flowvolume curve (MEFV) were measured in 35 normal subject, 43 patients with remission asthma and 100 patients with remission chronic bronchitis (some complicated by obstructive emphysema). The measured values showed that in simple asthma Raw was significantly higher than that in normal subject and in patients with chronic obstructive bronchitis (COB), but MEFV was in normal range. In chronic bronchitis the value of Raw was higher than that in normal subject, but lower than that in asthma (0.05 > P > 0.02); however the FEV1, MMEF, V75 in the curve of MEFV were significantly decreased at the stage of COB, with the most remarkable decrease in MMEF. The results suggest that Raw is a sentitive test for diagnosis of simple asthma, in addition to MEFV measurement; it may be helpful for differential diagnosis of simple asthma and COB and may has potential value for clinical practice.

[Diagnostic value of exercise diffusion capacity test on diffuse pulmonary fibrosis]

Diffusion capacity for carbon monoxide of the lung (DLCO) before-and-after exercise test and 5 routine pulmonary function tests were conducted in 16 patients with diffuse pulmonary fibrosis (DPF), 19 patients with interstitial pneumonia (IP), 17 patients with COPD, and 22 normal subjects. The data showed: in normal subjects the DLCO after exercise increased significantly compared with before (P < 0.001). But in DPF group the DLCO before exercise was below the normal range, and it went down further after exercise, the decreasing rate being 17.95% (P < 0.001). The DLCO in IP and COPD groups did not significantly change before and after the exercise. Two cases of interstitial pneumonia, who had a reduced DLCO after exercise, were followed up for 0.5-1.0 year, and both patients developed into DPF by that time. The results suggest that the DLCO measure before and after exercise test may have important value for DPF diagnosis, and a reduced DLCO after exercise test in IP patients may warn the development from IP into DPF.

In its active form, the GTP-binding protein rab8 interacts with a stress-activated protein kinase

Rab8 is a small GTP-binding protein that plays a role in vesicular transport from the trans-Golgi network to the basolateral plasma membrane in polarized epithelial cells (MDCK), and to the dendritic surface in hippocampal neurons. As is the case for most other rab proteins, the precise molecular interactions by which rab8 carries out its function remain to be elucidated. Here we report the identification and the complete cDNA-derived amino acid sequence of a murine rab8-interacting protein (rab8ip) that specifically interacts with rab8 in a GTP-dependent manner. Rab8ip displays 93% identity with the GC kinase, a serine/threonine protein kinase recently identified in human lymphoid tissue that is activated in the stress response. Like the GC kinase, rab8ip has protein kinase activity manifested by autophosphorylation and phosphorylation of the classical serine/threonine protein kinase substrates, myelin basic protein and casein. When coexpressed in transfected 293T cells, rab8 and the rab8ip/GC kinase formed a complex that could be recovered by immunoprecipitation with antibodies to rab8. Cell fractionation and immunofluorescence analyses indicate that in MDCK cells endogenous rab8ip is present both in the cytosol and as a peripheral membrane protein concentrated in the Golgi region and basolateral plasma membrane domains, sites where rab8 itself is also located. In light of recent evidence that rab proteins may act by promoting the stabilization of SNARE complexes, the specific GTP-dependent association of rab8 with the rab8ip/GC kinase raises the possibility that rab-regulated protein phosphorylation is important for vesicle targeting or fusion. Moreover, the rab8ip/GC kinase may serve to modulate secretion in response to stress stimuli.

[Measurement of maximal inspiratory flow and forced inspiratory capacity and its clinical application]

The methods of measuring the maximal inspiratory flow (V(imax)) and the forced inspiratory capacity (FIC) via forced inspiratory capacity-time curve (FIC-t curve) were investigated. Both V(imax) and FIC were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The maximal inspiratory pressure (MIP) was measured simultaneously at function residual capacity(FRC) level by modified Black Method. The results showed that there is a linear relationship between MIP and V(imax) or FIC in both normal subjects and patients with COPD. Normal subjects had a mean V(imax) and FIC much higher than those of patients with COPD. The values of V(imax) and FIC in patients were also, significantly correlated to the severity of COPD. So we suggest that both V(imax) and FIC be used as clinical indices to reflect inspiratory muscles strength.

[A study on the simultaneous HPLC determination of chlorhexidine and its impurity 4-chloroaniline]

This paper reports a new RP-HPLC method using phenacetin internal standard (IS) for simultaneous determination of chlorhexidine (CH) and its impurity 4-chloroaniline (4-CA). We use the LC-3A HPLC instrument, a Zorbax-C8 column (25cm x 4.6mm id, 10 microns), a variable wave length UV detector and C-RIA chromatographic data processor. A mixture of methanol and 0.2 mol/L NaH2PO4 (50.5 : 49.5, pH 3.0) is used as mobile phase, whose flow rate is 1.0 ml/min. Sample solution of 15 microliters is injected onto the column, which is maintained at 30 degrees C. The eluent is monitored at 240nm. The retention times are 16.72 min for CH and 5.54 min for 4-CA. The standard curves of CH and 4-CA are established using peak area ratio of CH/IS and 4-CA/IS to concentration respectively. They are both linear (r = 0.9999) within 15-200 micrograms/ml for CH and 60-1200 micrograms/ml for 4-CH. The limits of detection are 1.33 micrograms/ml for CH AND 7.5 micrograms/ml for 4-CA (S/N = 3). The analytical recovery rates are 100.1% for CH and 103.1% for 4-CA. This method has been used for investigating the stability of CH preparation.

Two components of the delayed rectifier K+ current in ventricular myocytes of the guinea pig type. Theoretical formulation and their role in repolarization

Two distinct delayed rectifier K+ currents, IKr and IKs, were found recently in ventricular cells. We formulated these currents theoretically and investigated their roles in action potential repolarization and the restitution of action potential duration (APD). The Luo-Rudy (L-R) model of the ventricular action potential was used in the simulations. The single delayed rectifier K+ current in the model was replaced by IKr and IKs. Our results show that IKs is the major outward current during the plateau repolarization. A specific block of either IKr or IKs can effectively prolong APD to the same degree. Therefore, either channel provides a target for class III antiarrhythmic drugs. In the simulated guinea pig ventricular cell, complete block of IKr does not result in early afterdepolarizations (EADs). In contrast, > 80% block of IKs results in abnormal repolarization and EADs. This behavior reflects the high IKs-to-IKr density ratio (approximately 8:1) in this cell and can be reversed (ie, IKr block can cause EADs) by reducing the ratio of IKs to IKr. The computed APD restitution curve is consistent with the experimental behavior, displaying fast APD variation at short diastolic intervals (DIs) and downward shift at longer DIs with the decrease of basic drive cycle length (BCL). Examining the ionic currents and their underlying kinetic processes, we found that activation of both IKr and IKs is the primary determinant of the APD restitution at shorter DIs, with Ca2+ current through L-type channels (ICa) playing a minor role. The rate of APD change depends on the relative densities of IKr and IKs; it increases when the IKr-to-IKs density ratio is large. The BCL-dependent shift of restitution at longer DIs is primarily attributed to long-lasting changes in [Ca2+]i. This in turn causes different degrees of Ca(2+)-dependent inactivation of ICa and different degrees of Ca(2+)-dependent conductance of IKs at very long DIs (> 5 s) for different BCLs. This BCL dependence of ICa and IKs that is secondary to long-lasting changes in [Ca2+]i is responsible for APD changes at long DIs and can be viewed as a "memory property" of cardiac cells.

The influence of thymectomy on germ-cells of the testis in mice

We performed thymectomy on the immature and mature male mice and made a quantitative assay of various germ cells of the seminiferous epithelium in the testis with Image Analyser System 35 days following thymectomy. The results indicated that as compared with the control group, all germ cells of the spermatogenesis lineage decreased in the immature group and in the mature group after thymectomy. The present study showed that thymus and its hormone stimulated not only the mitotic division, but also the meiotic division of germ cells during spermatogenesis, suggesting that thymus-sexual axis may play an important role in the process of spermatogenesis in the testis.

[Measurement of the reserve function of inspiratory muscle and its clinical significance]

The principles of measuring inspiratory muscle tension-time index (TTim) and the ratio of the works of inspiration over the maximal works of inspiration (Wi/Wi(max)) were investigated and their formulae were deduced, i.e. TTim = (Pi x Ti)/(MIP x Ttot) and Wi/Wi(max) = (Pi x VT)/(MIP x IC). The importance of the inspiratory pressure and the maximal inspiratory pressure (MIP) measured at function residual capacity (FRC) level was emphasized. Both TTim and Wi/Wi(max) were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The results showed that normal value of TTim was 0.0253 +/- 0.0055 which corresponds to the normal value of the diaphragm tension-time index (TTdi = 0.02-0.03) reported by Bellemare. Patients with COPD had a mean TTim much higher than that of normals (P < 0.01). The works of inspiration (Wi) in patients with COPD increased, while the maximal works of inspiration (Wi(max)) declined, so Wi/Wi(max) became significantly greater than that of normals (P < 0.01). The results also showed that there was a linear relationship between Pi/Pimax and TTim or Wi/Wimax (r = 0.7891, 0.9738, 0.6459, 0.9327, P < 0.01). Therefore, we suggest that both TTim and Wi/Wimax can be used as clinical indices to reflect the reserve function of inspiratory muscles.

Early afterdepolarizations in cardiac myocytes: mechanism and rate dependence

A model of the cardiac ventricular action potential that accounts for dynamic changes in ionic concentrations was used to study the mechanism, characteristics, and rate dependence of early after depolarizations (EADs). A simulation approach to the study of the effects of pharmacological agents on cellular processes was introduced. The simulation results are qualitatively consistent with experimental observations and help resolve contradictory conclusions in the literature regarding the mechanism of EADs. Our results demonstrate that: 1) the L-type calcium current, ICa, is necessary as a depolarizing charge carrier during an EAD; 2) recovery and reactivation of ICa is the mechanism of EAD formation, independent of the intervention used to induce the EADs (cesium, Bay K 8644, or isoproterenol were used in our simulations, following similar published experimental protocols); 3) high [Ca2+]i is not required for EADs to develop and calcium release by the sarcoplasmic reticulum does not occur during the EAD; 4) although the primary mechanism of EAD formation is recovery of ICa, other plateau currents can modulate EAD formation by affecting the balance of currents during a conditional phase before the EAD take-off; and 5) EADs are present at drive cycle lengths longer than 1000 ms. Because of the very long activation time constant of the delayed rectifier potassium current, IK, the activation gate of IK does not deactivate completely between consecutive stimuli at fast rates (drive cycle length < 1000 ms). As a result, IK plays a key role in determining the rate dependence of EADs.

ATPase activities of rabbit and bovine lens epithelial microsomes: a continuous fluorimetric assay study

Purine nucleoside phosphorylase (EC 2.4.2.1) catalyzes the irreversible phosphorolysis of 7-methylguanosine (m7Guo), a fluorescent guanosine analogue. Using purine nucleoside phosphorylase and m7Guo, a continuous fluorimetric assay for microsomal ATPases from rabbit and bovine lens is described. The decrease in m7Guo fluorescence intensity at 380 nm, which represents the hydrolysis of ATP, is linear with time up to exhausting all m7Guo. The rate of the fluorescence decrease depends on the sample protein concentration. In the presence of ATPase inhibitors, ion-specific ATPase activities in the lens were determined from the difference of the fluorescence decay rates. Using the fluorimetric assay thapsigargin-sensitive Ca-ATPase in the bovine lens epithelium has been characterized. The fluorimetric assay provides a number of advantages over previous membrane ATPase assays.

Effect of ethanol-induced lipid interdigitation on the membrane solubility of Prodan, Acdan, and Laurdan

The effect of ethanol-induced lipid interdigitation on the partition coefficient (Kp) of 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and its two derivatives, 6-acetyl-2-(dimethylamino)naphthalene (Acdan) and 6-lauroyl-2-(dimethylamino)naphthalene (Laurdan), in L-alpha-dipalmitoylphosphatidylcholine (DPPC) vesicles has been examined by a precipitation method over the ethanol concentration range of 0-1.8 M. At 20 degrees C and in the absence of ethanol, the Kp values for Acdan, Prodan, and Laurdan are 2.0 x 10(3), 2.8 x 10(4), and 4.7 x 10(6), respectively. This result suggests that the Kp of Prodan and its derivatives is not simply a linear function of the polymethylene units. As DPPC undergoes the ethanol-induced phase transition from the noninterdigitated to the fully interdigitated gel state, Kp for Prodan and Acdan decreases by a factor of 5 and 2, respectively, whereas Kp for Laurdan exhibits no detectable changes with ethanol. The differences in Kp are in parallel with the differences in the fluorescence emission spectra of these probes over the ethanol concentration range examined. Previous fluorescence and infrared data indicated that membrane perturbation caused by the probes increases in the order: Laurdan > Prodan > Acdan. Thus, the degree of membrane perturbation also seems to be in parallel with Kp. Among these three probes, Prodan fluorescence reflects most correctly the ethanol-induced lipid interdigitation. In conclusion, the partitioning of small solutes in lipid membranes is significantly reduced by ethanol-induced lipid interdigitation, probably as a result of an increased membrane surface density due to the increased intramolecular lipid acyl chain ordering and a tighter overall intermolecular packing.

The effect of thyroid hormone treatment on the gene expression and enzyme activity of rat liver sodium-potassium dependent adenosine triphosphatase

The effects of thyroid hormone (T3) treatment on liver Na,K-adenosine triphosphatase (Na,K-ATPase) at the levels of subunit messenger RNA (mRNA), enzymatic activity, and enzyme content were studied in euthyroid rats injected for 5 consecutive days with T3. Northern and slot blot analyses of polyadenylated mRNA revealed that T3 treatment coordinately increases the level of mRNA encoding the alpha 1- and beta 1-subunits, approximately 4- and 3-fold, respectively, above basal levels. To determine whether this increase in the subunit mRNA consequently results in an increase in the synthesis of the enzyme, a modified liver cell fractionation procedure was developed, and the subcellular fractions from control and T3-treated livers were examined biochemically. Western blot analysis and Na,K-ATPase assay demonstrated that T3 treatment resulted in a 2-fold increase in both the amount and activity of the enzyme. Furthermore, the Western blot analysis of endoglycosidase-H-treated membrane fractions revealed an increase in the amount of the precursor beta-subunit in the T3-treated liver rough microsomal fraction, suggesting that an increase in subunit synthesis contributes at least partially to the increase in the rat liver Na,K-ATPase by T3 treatment.

Structure of the green heme in myeloperoxidase

A 3-A-resolution X-ray crystal structure of canine myeloperoxidase has previously revealed the overall structure of the molecule, including the polypeptide backbone conformation, but did not provide an unambiguous structure for the covalently bound heme. A higher resolution (2.28 A) X-ray crystal structure of human myeloperoxidase has now shown that the heme is a novel derivative of protoporphyrin IX in which three ring substituents form covalent bonds with amino acid side chains in the protein. Modified methyl groups on pyrrole rings A and C form ester linkages with glutamate 242 and aspartate 94, while a covalent bond between the vinyl group on ring A and the sulfur atom of methionine 243 results in a sulfonium ion linkage. The heme tetrapyrrole ring also shows considerable distortion from the planar conformation seen in most heme-containing proteins. The observed bending appears to result from these covalent bonds between diametrically opposed pyrrole rings A and C and the protein. Sequence comparisons suggest that the two ester linkages to the heme may also occur in other homologous mammalian peroxidases, but that the sulfonium ion linkage may be a unique feature of myeloperoxidase.

Chinese character operating system of traditional Chinese medicine and pharmacology (TCMP)

With the development in research, teaching and literature work in traditional Chinese medicine and pharmacology (TCMP) by means of computers, it has been found that the existing Chinese character operative systems cannot meet the need of carrying out information processing and software development in this field, since these systems do not include many of the common and special terms in TCMP. This makes it inconvenient to exchange academic thoughts in information processing in this field with our colleagues at home and abroad and greatly affects the sharing of the literature data in TCMP. It is therefore necessary to develop a Chinese character operating system applicable to the use of computers in the research of TCMP. Recently, we have developed jointly a Chinese character operating system of TCMP. This system is based on the original GB2312-80 Chinese character international code, to which are added 1,150 Chinese characters commonly used in TCMP. The five-stroke code, which make input possible according to word forms, are used for the input of expanded words. Besides, the system also provides the codes of a number of common names of Chinese materia medica, acupoint names, common terms in traditional Chinese medicine (TCM), TCM disease names, names of classic TCM works, etc. It also provides a convenient character-creating software. We hope that our work will lead to discussions concerning the difficult problems in computer processing of TCMP literature, i.e. the Chinese character.

Oligosaccharides from human milk as revealed by matrix-assisted laser desorption/ionization mass spectrometry

In this study neutral and acidic oligosaccharide fractions prepared from human milk have been investigated using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The fraction of neutral oligosaccharides was separated by gel permeation chromatography (GPC) and the resulting subfractions were analyzed by MALDI-MS using the positive ion mode. Several low-molecular-weight glycans (degree of polymerization up to 13) were observed whose structures have already been elucidated. In addition, a variety of so far unknown large-sized carbohydrates was detected whose molecular weights range from M(r) 2242 to 8000. The large-sized glycans which possess a low abundance appear to be composed of both lactosamine and fucose residues attached to the lactose unit at the reducing end of the sugar chains with a highly variable stochiometry. Following subfractionation by GPC, acidic (i.e., containing sialic acid) glycans were analyzed by MALDI-MS using both positive and negative ion mode. Because of the inferior stability of acidic glycans, various matrices were applied and compared with respect to signal intensity, resolution, and analyte stability.

Differential cDNA cloning by enzymatic degrading subtraction (EDS)

We describe a new method, called enzymatic degrading subtraction (EDS), for the construction of subtractive libraries from PCR amplified cDNA. The novel features of this method are that i) the tester DNA is blocked by thionucleotide incorporation; ii) the rate of hybridization is accelerated by phenol-emulsion reassociation; and iii) the driver cDNA and hybrid molecules are enzymatically removed by digestion with exonucleases III and VII rather than by physical partitioning. We demonstrate the utility of EDS by constructing a subtractive library enriched for cDNAs expressed in adult but not in embryonic rat brains.

[Expression of human chorionic gonadotropin, human placental lactogen and pregnancy-specific 1-glycoprotein in malignant trophoblastic neoplasms]

The expression of placental hormones in 91 malignant trophoblastic neoplasms was studied immunohistochemically using a panel of antibodies against hCG, human placental lactogen (hPL) and pregnancy-specific 1-glycoprotein (SP). The results indicated that the expression of hCG in invasive moles was weaker than that in choriocarcinoma, but the expression of hPL and SP1 was stronger than those in choriocarcinoma. The expression of hPL and SP1 in the metastatic tumors of invasive moles was weaker than the expression at in the primary tumors, but the secretory capacity of hCG in metastatic choriocarcinomas was stronger than that in the primary neoplasms. In this study, the qualities of expression of the placental hormones in invasive moles and choriocarcinomas corresponded to the degree of tumor malignancy, the biological behaviour and the grading of trophoblastic cell differentiation. We believe that the detection of hCG, hPL and SP1, in malignant trophoblastic neoplasms was of value for establishing tumor diagnosis and typing and for judgement on prognosis.

Identification and zinc dependence of the bovine herpesvirus 1 transactivator protein BICP0

Bovine herpesvirus 1 (BHV-1) specifies and unspliced early 2.6-kb RNA (ER2.6) which is 3' coterminal with exon 2 of the 2.9-kb immediate-early (IE) RNA. The two transcripts have a common open reading frame (676 codons). The predicted protein, designated BHV-1 infected cell protein 0 (BICP0), contains a zinc finger domain with homology to ICP0 of herpes simplex virus type 1 and protein 61 of varicella-zoster virus, and depending on the promoter, it acts as a strong activator or as a repressor in transient expression assays. In situ immunoadsorbent assays using antisera against synthetic oligopeptides demonstrated that BICP0 accumulates in nuclei of BHV-1-infected cells, as expected for an IE gene product involved in gene regulation. Western blots (immunoblots) revealed a BHV-1-specific 97-kDa protein which was detectable during the IE phase and also at later periods of infection, indicating that the kinetics of BICP0 synthesis is consistent with the switch from IER2.9 to ER2.6. To confirm that ER2.6 encoded the 97-kDa BICP0 protein, a DNA fragment containing BICP0-coding sequences was inserted into the Autographa californica baculovirus genome. A recombinant protein, identified by its reactivity with antipeptide sera, exhibited the same electrophoretic mobility as BICP0 specified by BHV-1. We microinjected Xenopus oocytes with a BICP0 effector plasmid and a promoter-chloramphenicol acetyltransferase plasmid. BICP0-induced stimulation of this promoter was strongly reduced when intracellular zinc was chelated by thionein, indicating that the effect of BICP0 is zinc dependent.

[Determination of ceftizoxime in serum by high performance liquid chromatography]

This paper reports the determination of ceftizoxime, a new cephalosporin antibiotic, in serum by RP-HPLC. The technique for serum protein precipitation by adding perchloric acid is adapted for sample preparations. After centrifugation, a 100 microliters portion of aqueous phase is injected into chromatographic column of ultrasphere CN, the mobile phase being a mixture of methanol and 1% acetic acid (15:85). The standard curve is linear within the range of 2.5-120 mg/L in serum. The detection limit of ceftizoxime in serum stands at 0.1 mg/L. The recoveries from serum samples after protein precipitation reach 95.4-96.3%. The within day CVs and interday CVs are 2.7-3.3% and 4.8-7.6%, respectively. This method is rapid, reliable and reproducible. It has been utilized to measure the concentration of ceftizoxime in patient serum for clinical research and pharmacokinetic studies.

Effects of alcohol-induced lipid interdigitation on proton permeability in L-alpha-dipalmitoylphosphatidylcholine vesicles

6-Carboxyfluorescein was employed to examine the effect of alcohol-induced lipid interdigitation on proton permeability in L-alpha-dipalmitoylphosphatidylcholine (DPPC) large unilamellar vesicles. Proton permeability was measured by monitoring the decrease of 6-carboxyfluorescein fluorescence after a pH gradient from 3.5 (outside the vesicle) to 8.0 (inside the vesicle) was established. At 20 degrees C and below 1.2 M ethanol, the fluorescence decrease is best described by a single exponential function. Above 1.2 M ethanol, the intensity decrease is better described by a two-exponential decay law. Using the fitted rate constants and the vesicle radii determined from light-scattering measurements, the proton permeability coefficient, P, in DPPC vesicles was calculated as a function of ethanol concentration. At 20 degrees C, P increases monotonically with increasing ethanol content up to 1.0 M, followed by an abrupt increase at 1.2 M. The vesicle size also exhibits a sudden increase at around 1.2 M ethanol, which has been shown to result from vesicle aggregation rather than vesicle fusion. The abrupt increases in P and in vesicle size occur at the concentration region close to the critical ethanol concentration for the formation of the fully interdigitated gel state of DPPC. At 14 degrees C, the abrupt change in P shifts to 1.9-2.0 M ethanol, completely in accordance with the ethanol-temperature phase diagram of interdigitated DPPC. Effects of methanol and benzyl alcohol on lipid interdigitation have also been examined. At 20 degrees C, DPPC large unilamellar vesicles exhibit a dramatic change in P at 3 M methanol and at 40 mM benzyl alcohol. These concentrations come close to the critical methanol and benzyl alcohol concentrations for the formation of fully interdigitated DPPC structures determined previously by others. It can be concluded that proton permeability increases dramatically as DPPC is transformed from the noninterdigitated gel to the fully interdigitated gel state by high concentrations of alcohol. This marked increase in proton permeability can be attributed to the combined effect of the changes in membrane thickness and surface charge density, due to the ethanol-induced lipid interdigitation. The possible effects of the increased proton permeability caused by ingested ethanol on gastric mucosal membranes are discussed.

Influence of thymosin on the level of cyclic nucleotides in rats with experimental varicocele

Experimental varicocele was induced by partial ligation of the left renal vein in rats, and the effect of thymosin (fraction 5), a hormone secreted by the thymus, on the level of cyclic nucleotides was investigated. The levels of cAMP and cGMP in plasma and testicular tissue were estimated using radioimmunoassay techniques. The results showed that the level of cAMP in bilateral testicular tissues in rats with experimental varicocele decreased considerably, especially in the left testicular tissue as compared with that in the control group (P < 0.05). 4 weeks after thymosin administration (0.5 mg/rat, twice a week), the level of cAMP in bilateral testicular tissues rose significantly, as compared with that in the experimental varicocele group (P < 0.01). These findings indicate that there exists imbalance in the metabolism of cyclic nucleotides in rats with experimental varicocele. This suggests that the abnormal level of cyclic nucleotides is one of the causes of infertility with varicocele. Since thymosin participates in the metabolism and regulation of cyclic nucleotides, it may have a direct or an indirect effect on the growth and function of reproductive cells.

Effects of thymosin on the secretion of the sexual hormone in rats with experimental varicocele

Hormonal abnormality in experimental varicocele induced by partial ligation of left renal vein and the effect of thymosin (fraction 5) on the secretion of the sexual hormone were studied in rats. Serum testosterone level was lowered after varicocele formation, but could be reversed or increased by intraperitoneal administration of thymosin 5 mg/rat twice a week for 4 weeks with concomitant increase of testicular testosterone content. Changes in FSH and LH both in serum and testis, determined with immunoassay method as that of testosterone, were insignificant as compared with control or thymosin treated groups.

[The use of domestic viscoelastic substances in IOL implantation and their toxicity to endothelial cells in vitro]

34 senile cataract patients were randomly divided into groups of 1% sodium hyaluronate (Healon) 14 patients, 2% hydroxypropylmethylcellulose (HPMC) 10 patients and Viscose 10 patients for extracapsular cataract extraction with IOL implantation. The rate of endothelial cell loss, the corneal thickness, the intraocular pressure, and the anterior chamber reactions were investigated; the toxicity of the viscoelastic substances on human corneal endothelial cells was studied in vitro for comparative evaluation.

[High performance liquid chromatographic determination of hydroxyphenytoin in human urine]

A high-performance liquid chromatographic method for the determination of p-hydroxyphenytoin (p-HDPH) in human urine was reported. Following acid hydrolysis of urine sample at 90 degrees C for 1 h, an internal standard, nitrophenol, was added. The sample was extracted with n-hexane-ethyl acetate (50:50), and organic layer was evaporated. The residue was dissolved in methanol and chromatographed on an Ultrasphere-ODS column, using a mobile phase of phosphate buffer (0.03 mol/L, pH 6.0): methanol (65:35) at a flow rate of 0.8 ml/min. The eluent was monitored at 240 nm. The standard curve was linear within the range 5.0-200 micrograms/ml (r = 0.9998). Analytical recovery rates were 102.8 +/- 7.3% (p-HDPH 9.70 micrograms/ml, n = 5) and 104.9 +/- 6.4% (p-HDPH 54.70 micrograms/ml, n = 5). The cumulative recovery of p-HDPH in 0-12 h volunteers' urine samples accounted for 20% of the oral dose of 100 mg phenytoin sodium.