Effects of berbamine on intracellular calcium concentration in cultured HeLa cells

AIM

To study the involvement of Ca2+ signaling and the effects of berbamine (Ber) on intracellular calcium concentration ([Ca2+]i) elevated in cultured HeLa cells.

METHODS

[Ca2+]i was measured by confocal microscopy in single HeLa cell loaded with Fluo 3-AM. The change of [Ca2+]i was represented by fluorescent intensity (FI).

RESULTS

(1) In the presence of extracellular Ca2+ 1.3 mmol.L-1, the resting level of FI was 186 +/- 44, n = 49 cells from all control experiments, and KCl, NE, caffeine, and calcimycin (Cal) all induced [Ca2+]i elevations in cultured HeLa cells. (2) The resting level of FI was not affected by pretreatment with Ber. The FI increased by KCl 60 mmol.L-1, NE 100 micromol.L-1, and Cal 30 micromol.L-1 were attenuated (P < 0.05 or P < 0.01), the slope and the time to peak of FI increase were decreased and prolonged. (3) In the absence of extracellular Ca2+, caffeine 80 mmol.L-1-induced [Ca2+]i mobilization was not inhibited by Ber 100 micromol.L-1 pretreatment. (4) These effects of Ber were similar to those of verapamil (Ver) 10 mumol.L-1.

CONCLUSION

Although it was derived from cervical cancer, the HeLa cells which were belong to the nonexcitable cell possessed the similar biological properties with excitable cells, and Ca2+ also played a crucial role in signal transduction processes.

Integrin alphavbeta3-RGDS interaction mediates fibrin-induced morphological changes of glomerular endothelial cells

BACKGROUND

In our previous studies, we found that intraglomerular deposition of fibrin and its metabolites was related to glomerular sclerosis and reduced renal function. It has been reported that both overlying and underlying fibrin may induce specific morphological changes of cultured endothelial cells from large blood vessels. The dependency of these morphological changes on the integrin alphavbeta3-arginyl-glycyl-aspartyl-serine (RGDS) interaction is still controversial. We hypothesized that glomerular endothelial cells (GECs) stimulated by fibrin might undergo morphological changes through an integrin alphavbeta3-RGDS interaction. Methods. In vitro studies were performed to examine the growing status of GECs stimulated by overlying and underlying fibrin gels in the presence or absence of the following: 50 microg/ml anti-alphavbeta3 integrin monoclonal antibody 23C6 or nonimmune mouse IgG, 1 mg/ml synthetic RGDS or arginyl-glycyl-glycyl-serine (RGGS) peptide, 10 mg/ml sodium heparin, 100 microg/ml cycloheximide, and 10 microM actinomycin D. Fast protein liquid chromatography (FPLC)-purified fibrinogen and the third to fifth passages of human GECs were also used in this study.

RESULTS

GECs developed capillary tube structure after 60 hours of culturing on fibrin gels, and GECs cultured on gelatin-coated plates displayed a monolayer of cobblestone-like cells in the presence or absence of 23C6 and synthetic RGDS peptide. Fibrin-induced capillary tube formation was promoted by 23C6 and inhibited by RGDS peptide, cycloheximide, and actinomycin D. Disorganization of the GEC monolayer was induced by overlying fibrin, but was not induced by overlying agarose gels and glass cover slips or culturing in fibrinogen, 0.05 NIH U/ml thrombin, fibrin supernatants, as well as in fibrin degradation products. Disorganization of GEC monolayer can be induced by both des-AA-fibrin and des-AABB-fibrin and was unaffected by heparin. Furthermore, both 23C6 and synthetic RGDS peptide prevented disorganization of GECs induced by overlying fibrin, whereas nonimmune mouse IgG, synthetic RGGS peptide, cycloheximide, and actinomycin D had no similar effect.

CONCLUSIONS

GECs cultured on fibrin gels may develop capillary structure spontaneously, and GECs covered by fibrin gels may undergo disorganization. Our data suggest that these GEC morphological changes are mediated by an integrin alphavbeta3-RGDS interaction.

Length bounded molecular computing

The length of DNA strands is an important resource in DNA computing. We show how to decrease strand lengths in known molecular algorithms for some NP-complete problems, such as like 3-SAT and Independent Set, without substantially increasing their running time or volume.

An O(2n) volume molecular algorithm for Hamiltonian path

We design volume-efficient molecular algorithms for all problems in #P, using only reasonable biological operations. In particular, we give a polynomial-time 0(2(n)n2log2n)-volume algorithm to compute the number of Hamiltonian paths in an n-node graph. This improves Adleman's celebrated n!-volume algorithm for finding a single Hamiltonian path.

[Effect of plasminogen activator inhibitor 1 gene transfer into mesangial cells on Extracellular matrix accumulation]

OBJECTIVE

To observe the influence of plasminogen activator inhibitor 1 (PAI-1) overexpression on extracellular matrix (ECM) accumulation of rat mesangial cells.

METHODS

PAI-1/GFP green fluorescent protein fusion gene eukaryotic expression vector pCMX-PAI-1-GFP was constructed and delivered into cultured rat mesangial cells by liposome. PAI-1/GFP expression was observed by fluorescent microscope. FN, LN and Type IV collagen levels were measured by Northern blot analysis and ELISA method.

RESULTS

Northern blot analysis, SDS-PAGE analysis and Western blot analysis demonstrated that PAI-1/GFP gene can be transcripted and translated in rat mesangial cells. PAI-1/GFP gene can express a specific protein. The recombinant PAI-1/GFP had significant inhibition activity on urokinase-type plasminogen activator and displayed autonomous fluorescence. The PA activity of cell supernatants decreased markedly in gene transfer group. FN, LN and Type IV collagen levels were higher than in a control group.

CONCLUSION

Over-expression of PAI-1 gene leads to mesangial ECM accumulation. The changes of PA/PAI-1 activity in supernatants of cultured rat mesangial cells might be the key factor in ECM accumulation regulation.

Abnormalities of tumor suppressor genes P16 and P15 in primary maxillofacial squamous cell carcinomas

As members of the same gene family, tumor suppressor genes P16/CDKN2/INK4A and P15/INK4B have a high degree of structural and functional homology with both P16 and P15 proteins involved directly in the regulation of cell cycles. However, the status of P16 and P15 genes in primary maxillofacial squamous cell carcinomas (MSCC) has not been reported. Studies on abnormalities of these genes including homozygous deletion, methylation of the 5'CpG islands, and mutations were carried out in 65 primary MSCC with polymerase chain reaction (PCR), methylation-specific PCR (MSP), PCR-SSCP (single-strand conformation polymorphism), and DNA sequencing techniques. Of the 65 tumors, 22 (34%) were methylated; 7 (11%) displayed point mutations. The total frequency of alteration of the P16 gene was 43% (28/65). The methylation rate of P15 was 12% (8/65). No homozygous deletion was found in either the P16 gene or P15 gene. In all MSCC samples, almost half (49%) harbored an alteration of the P16 or P15 gene. The P16 gene was altered more frequently than P15, and therefore is inactivated by methylation or mutation in a significant proportion of MSCC. The P15 gene appeared to play a lesser role in tumorigenesis of these tumors.

Factor V Leiden and thermolabile methylenetetrahydrofolate reductase gene variants in an East Anglian preeclampsia cohort

Preeclampsia is a heritable condition that develops as a result of widespread vascular endothelial dysfunction. The thrombotic tendency in this condition has suggested a number of candidate genes, and there have been recent reports of positive association with the Leiden variant of factor V and the thermolabile variant of methylenetetrahydrofolate reductase. We attempted to reproduce these results in a large cohort of well-characterized women with preeclampsia, recruited prospectively within the East Anglian region of the United Kingdom. Women in the preeclampsia cohort (n=283) were genotyped for both the Leiden variant (G1691A) of factor V and the thermolabile variant (C677T) of methylenetetrahydrofolate reductase. Genotype and allele frequencies were compared with those of 2 control groups, one consisting of women recruited prospectively (n=100) from the same maternity hospital as the subjects and another consisting of normotensive women (n=100) from East Anglia. No significant differences were detected. Specifically, the carrier rate for the Leiden variant was 5.3% in the preeclampsia group and 5. 5% in the combined control group. T677 homozygotes for methylenetetrahydrofolate reductase were 11% and 11.5% in the 2 groups, respectively. We conclude that there is no evidence of association of preeclampsia with either of these 2 polymorphisms in our study population.

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

[Expression of GST-pi gene in human esophageal carcinogenesis]

OBJECTIVE

To investigate the possible role of GST-pi in esophageal carcinogenesis.

METHODS

GST-pi expression at mRNA level was studied by in situ hybridization (ISH) and at protein level by immunohistochemistry (IHC). GST-pi expression of the esophagus in normal epithelial cells (NC), hyperplastic cells (HC), dysplastic cells (DC) from grade I to III, carcinoma in-situ (CIS) and invasive carcinoma (IC) was examined in the same esophageal cancer specimens (n = 48) which provided a model reflecting the process of esophageal carcinogenesis.

RESULTS

The positive rate of IHC staining was 87.5% for NC, 95.3% for HC, 55.9% for DC (grade I: 73.9%, grade II: 47.4%, grade III: 41.2%), 36.4% for CIS and 45.8% for IC. The positive rate of GST-pi mRNA expression was 81.2% for NC, 94.4% for HC, 61.9% for DC (grade I: 76.5%, grade II: 61.5%, grade III: 41.7%), 44.4% for CIS and 83.3% for grade I IC, 30.0% for grade II IC and 0% for grade III IC. There was no statistically significant difference in GST-pi expression at the mRNA and the protein level.

CONCLUSION

There is a decreasing tendency of GST-pi expression from dysplasia to CIS and IC. The decrease in GST-pi expression is an early event in esophageal carcinogenesis.

Linkage of Gordon's syndrome to the long arm of chromosome 17 in a region recently linked to familial essential hypertension

Gordon's syndrome (GS) is a salt-sensitive, hyperkalaemic, familial hypertension syndrome which may masquerade in milder forms as essential hypertension. The response of hyperakalaemia to dietary salt restriction and to mineralocorticoids is heterogeneous, suggesting genetic heterogeneity. In a recently published study using small pedigrees, possible linkage of GS to chromosomes 1 and 17 was described. Studying the largest pedigree so far reported with GS, and using fluorescent-labelled microsatellite markers, we sought evidence of linkage to chromosomes 1 and 17. In this family there was no segregation of GS with any of the markers for chromosome 1. On chromosome 17, however, evidence of linkage was found with a maximum multipoint LOD score of 2.4 (the maximum LOD possible from the pedigree) over markers D17S250 and D17S934. This represents strong evidence in this pedigree for a responsible gene mutation on the long arm of chromosome 17. Recent reports of linkage for essential hypertension and, especially, familial essential hypertension within the same area of chromosome 17 containing the D17S934 marker raise the possibility that the same gene may be responsible for familial essential hypertension and for Gordon's syndrome.

Genetic deletion of AT2 receptor antagonizes angiotensin II-induced apoptosis in fibroblasts of the mouse embryo

To examine whether angiotensin II (Ang II) can trigger apoptosis via Ang II type 2 (AT2) receptor, two genotypes of skin fibroblasts cultured from the AT2 receptor gene targeting homozygous (AT2-/-) and wild-type (AT2+/+) mouse embryos, respectively, were studied when exposed to Ang II. In the AT2+/+ fibroblasts, mRNA expression of the AT2 receptor was modulated by Ang II in a dose-dependent manner and apoptosis appeared with the convincing features of internucleosomal DNA fragmentation and DNA content decrease after stimulation with Ang II, whereas Ang II had no significant impact on the AT2-/- fibroblasts due to the AT2 receptor gene deletion. This is the first report using a gene targeting study to demonstrate that Ang II induces apoptosis through the AT2 receptor in the fibroblasts of the mouse embryo.

Detection of filarial larvae in mosquitoes with oligonucleotide probe

OBJECTIVE

To investigate a new way to detect filarial larvae in mosquitoes and apply it to the surveillance of filariasis.

METHODS

An oligonucleotide probe that was species-specific to W. malayi was synthesized and marked with 32P using molecular biological technique. Then the probe was tested with dot hybridization in detection of W. malayi filarial larvae from mosquitoes.

RESULTS

The minimal detectable limit was found to be 2 ng DNA of filarial larvae or microfilaria (Mf.), with no cross reaction with other animal filariae. A single larva can be detected when infected mosquitoes were tested one by one. One infected mosquito can be detected from a group of 20 mosquitoes tested together.

CONCLUSIONS

Our probe is sensitive and specific. It is practical to apply our probe to mosquito surveillance in Brug's filariasis endemic areas.

[Three-dimensional volumetric display--a new application of frequency up-conversion]

This paper discusses the present research situation and the application prospect of 3-D volumetric display technology. The possible usability and science significance of frequency up-conversion in 3-D volumetric display field are also demonstrated systematically. In ZBLAN: Pr, Yb glasses, we primarily demonstrated and achieved a new application of frequency up-conversion three dimensional volumetric display, using the two-frequency up-conversion of the rare earth ions. The efficiency of luminescence of Pr was enhanced much by the energy transfer between Pr and Yb ions.

[Effects of Arg-Gly-Asp-Ser (RGDS) tetrapeptide on apoptosis-related genes in glomerular mesangial cells]

OBJECTIVE

To investigate the effects of Arg-Gly-Asp-Ser (RGDS) tetrapeptide on the expressions of apoptosis-related genes interleukin-1 beta-converting enzyme (ICE) and bcl-2 in human glomerular mesangial cells, so as to provide experimental evidence for regulating proliferation and apoptosis of mesangial cells with RGD-containing polypeptide.

METHODS

Propidium iodide staining was used to observe the condensation and fragmentation of apoptotic nuclei. The internucleosomal DNA fragmentation was detected by DNA electrophoresis on agarose gel. The expressions of ICE and Bcl-2 were determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

After ten hours of incubation, the glomerular mesangial cells treated with RGDS peptide displayed features consistent with apoptosis, such as nuclear condensation and fragmentation, and a regularly spaced "ladder" shape of genomic DNA electrophoresed. And RT-PCR showed that expressions of both ICE and Bcl-2 mRNAs were apparently increased in RGDS treated group, compared with that of the control group.

CONCLUSION

These results demonstrated for the first time that RGDS peptide was able to induce apoptosis in human glomerular mesangial cells, during the process ICE and bcl-2 genes may have an important regulating role.

[Hyperosmotic glucose and antibiotics induce production of plasminogen activator inhibitor and expression of TGF beta mRNA by rat peritoneal mesothelial cells]

To investigate the mechanism of fibrosis in peritoneal dialysis, we observed the effects of the hyperosmotic glucose and antibiotics such as gentamicin and cefazolin on rat peritoneal mesothelial cells with cell culture, fibrin-plate lyzing and Northern blotting analysis method. The peritoneal mesothelial cells may express PAI-1 mRNA. The expression of PAI-1 mRNA in peritoneal mesothelial cells and activities of PAI in the supernatants were enhanced by 11.2 mmol/L glucose, gentamicin and cefazolin at 12 hr. By 24 hr, the activity of PAI-1 also increased in the supernatants with 11.2 mmol/L glucose. The expression of PAI-1 mRNA and production of PAI activities by the peritoneal mesothelial cells were increased by gentamicin, and the TGF-beta mRNA increased in the peritoneal mesothelial cells was induced by 11.2 mmol/L glucose, gentamicin and cefazolin. The results suggested that 11.2 mmol/L glucose, gentamicin and cefazolin may increase the expressions or productions of PAI and TGF-beta in peritoneal mesothelial cells. So by perosmotic glucose, cefazolin and gentamicin promote the peritoneal fibrosis in patients with CAPD.

[Mechanisms of thrombin induced proliferation and detachment of glomerular endothelial cells]

To clarify the mechanisms of thrombin contributing to the progression of glomerular diseases by injuring glomerular endothelial cells (GECs), we studied the effects of thrombin on GECs in vitro. Cell proliferation was detected with MTT incorporation, total plasminogen activator (PA) and tissue type PA (t-PA) activities were detected with fibrin plate and chromatogenic substrate methods and fibronectin was detected with ELISA as well as indirect immunofluore scence. 0.4-3.2 NIH U/ml thrombin promoted GEC proliferation significantly (P < 0.05). Thrombin promoted cell detachment, which can be inhibited by hirudin or aprotinin. Thrombin enhanced total PA and t-PA activities of GECs significantly (P < 0.01). Fibronectin in the supernatants of thrombin-stimulated GECs decreased significantly (P < 0.01) and in the extracellular compartment also decreased. The decrease was inhibited by hirudin and aprotinin. In conclusion, thrombin can induce GEC proliferation and GEC detachment. The latter is probably related to PA-mediated over-degradation of extracellular matrices such as fibronectin, which are needed for cell attachment.

RGD-containing peptides trigger apoptosis in glomerular mesangial cells of adult human kidneys

Substantial evidence was given that different Arg-Gly-Asp (RGD)-containing peptides, linear Arg-Gly-Asp-Ser (RGDS) and cyclic Arg-Gly-Asp-Phe (RGDF), which are sequences present in fibronectin and vitronectin and which can bind alpha5beta1 and alpha(v)beta3 integrins, respectively, both induced apoptosis and expression of interleukin-1beta-converting enzyme (ICE) in cultured glomerular mesangial cells from adult human kidneys, with consistent apoptosis features appearing as nuclei condensation and fragmentation, internucleosomal DNA fragmentation, and DNA content decrease. These results indicated that both fibronectin and vitronectin may be important in the survival of human glomerular mesangial cells and that stable cyclic RGD(D)FV peptide may be a candidate to be used for regulating apoptosis in vivo.

A model for interpreting the tracer labeling of interendothelial clefts

We extended the model describing the low molecular weight electron dense tracer wake in the interendothelial cleft and surrounding tissue to describe the time-dependent transport of intermediate size solutes of 1.0-3.5 nm radius by convection and diffusion in an interendothelial cleft containing a fiber matrix. This model provides a quantitative basis on which to reinterpret electron microscopic studies of the distribution of tracers such as horseradish peroxidase (HRP; molecular weight = 40,000; Stokes radius = 3.0 nm) along the interendothelial cell cleft from the lumen to the tissue. For example, we show that, in contrast to our results with low molecular weight tracers, the wake of large molecular weight tracers on the abluminal side of the junctional strand is not likely to be detected, because the concentration of the tracer is predicted to be very low in most experiments. Thus the lack of a tracer such as HRP on the abluminal side of the junctional strand and in the tissue is not as strong evidence against the presence of a cleft pathway as suggested previously. The model does provide the basis for the design of experiments to locate both the principal molecular sieve and breaks in the junctional strand from the standing gradient on the luminal side of the junctional strand. An important experimental variable is the pressure in the vessel lumen which can be varied between 0 and 30 cm H2O to change the contributions of diffusive and convective transport to transcapillary exchange through he interendothelial cleft. This approach will also allow the testing of models for transcapillary pathways for large molecules by measuring the distribution of fluorescent traces across the microvessel wall and in the tissue surrounding the microvessel using confocal microscopy.

A new method of measuring heparin levels in whole blood by protamine titration using a heparin-responsive electrochemical sensor

OBJECTIVE

To determine the ability of a new electrochemical sensor to determine heparin levels in whole blood and to correlate the heparin levels as determined by this heparin-responsive sensor (HRS) with heparin levels as determined by the Hepcon assay system (Medtronic Hemotec, Parker, CO).

DESIGN

Methods comparison study.

SETTING

A large academic medical center.

INTERVENTIONS

The heparin levels of 162 samples from 24 patients undergoing cardiopulmonary bypass were determined by the HRS system and by the Hepcon system. In 21 samples, heparin levels as measured by anti-Xa activity were determined as well.

MEASUREMENTS AND MAIN RESULTS

HRS-determined values correlated highly with Hepcon-determined values (r = 0.942) and with anti-Xa determined values (r = 0.905). Bias +/- precision comparing the HRS and Hepcon methods was 0.211 +/- 0.478 U/mL.

CONCLUSIONS

HRS determined that whole blood heparin levels correlate well with Hepcon-determined levels. These limited results indicate that further development and testing of this new technology are warranted.

Processing of nutritious, safe and acceptable foods from CELSS candidate crops

A controlled ecological life-support system (CELSS) is required to sustain life for long-duration space missions. The challenge is preparing a wide variety of tasty, familiar, and nutritious foods from CELSS candidate crops under space environmental conditions. Conventional food processing technologies will have to be modified to adapt to the space environment. Extrusion is one of the processes being examined as a means of converting raw plant biomass into familiar foods. A nutrition-improved pasta has been developed using cowpea as a replacement for a portion of the durum semolina. A freeze-drying system that simulates the space conditions has also been developed. Other technologies that would fulfill the requirements of a CELSS will also be addressed.

Teaching microbiology with hypertext: first steps towards a virtual textbook

Computer-assisted learning materials for medical microbiology were developed using hypertext-authoring software (Folio 3.1). Two versions of a text-only introductory tutorial (detailed, read only, and read-write noteform) were then evaluated in a prospective, randomized trial. Evaluation was by pre- and post-exposure multiple choice questions, and by self-administered questionnaire. There was a small difference in outcome between the two groups; the read-write group scoring higher, and students who used either software performed better than those who did not (P = 0.014). Responses to the post-test questionnaires showed that many students regarded the read-only software as an electronic handout, more frequent users requesting the addition of illustrations, self-assessment questions, and greater interactivity. A small group of students made use of the read-write version of the tutorial as a 'virtual textbook' by adding extra material to the starter file. Our experience suggests that the low-cost option of text-only hypermedia produces only modest learning gains for medical undergraduates.

Clinical application of disposable heparin sensors. Blood heparin measurements during open heart surgery

The authors previously reported the development of an ion selective electrode type heparin sensor consisting of a specially formulated polymer membrane doped with tridodecylmethylammonium chloride as the heparin complexing agent. They also demonstrated the feasibility of measuring blood heparin levels by protamine titration, using a disposable copper wire sensor coated with the heparin sensing membrane to probe the titration end point. In this article, the results of further titration studies conducted on 44 clinical whole blood specimens obtained from 8 patients undergoing open heart surgery were reviewed. Samples were taken from patients at four different stages during the bypass surgery: 1) before heparin administration; 2) immediately after heparin administration; 3) within 30 min to 3 hr after heparin administration; and 4) within 30 min after protamine administration. Heparin anticoagulant activity in these samples was monitored by the activated clotting time assay, whereas heparin concentrations were measured by protamine titration using either the Hepcon HMS Titrator (Medtronic HemoTec Inc., Englewood, CO) or the coated wire heparin sensor to determine titration end points. Results indicate that heparin levels determined by the sensor method were in good agreement with those determined by the Hepcon HMS Titrator. When the heparin concentrations estimated by the two methods show significant discrepancy (> 1.0 unit/ml), the sensor method seems to provide more precise values, as verified by an additional chromogenic heparin assay. The overall time required to complete the titration process and heparin measurement with a pre made heparin sensor was less than 3 min. Clinically, the heparin sensor could be used as a safeguard to precisely monitor heparin levels during surgical procedures. Alternatively, the sensor could be used to assess the accurate protamine dose required for full heparin reversal.

Response mechanism of polymer membrane-based potentiometric polyion sensors

The potentiometric response mechanism of a previously reported polymer membrane-based electrode sensitive to the polyanion heparin is established. Based on transport and extraction studies, the heparin response is attributed to a nonequilibrium change in the phase boundary potential at the sample/membrane interface. While true equilibrium polyion response, obtained for low heparin concentrations only after very long equilibration times (> 20 h), yields the expected Nernstian response slope of < 1 mV/decade, the observed large and reproducible EMF response to clinically relevant heparin concentrations (approximately 10(-7) M) during typical measurement periods (2-5 min) is ascribed to a steady-state kinetic process defined by the flux of the polyion both to the surface and into the bulk of the polymer membrane. A model describing this nonequilibrium response is presented. With this model, the uniqueness of the polymer membrane composition (e.g., very low plasticizer content, strictly controlled cationic site concentration, etc.) required to achieve analytically useful heparin response becomes clear. Practical working conditions and limitations of the sensor are discussed. To support the generality of the steady-state model proposed, corresponding EMF response data for a newly developed membrane electrode sensitive to a polycationic protein (protamine) are also presented. It is shown that the protamine-responsive membrane electrode appears to operate via the exact same kinetic mechanism as the heparin sensing system.

A disposable, coated wire heparin sensor

The development of an ion-selective electrode heparin sensor consisting of a specially formulated polymer membrane doped with tridodecylmethylammonium chloride as the heparin complexing agent was recently reported. Because of the simple nature of the membrane technology used, the authors envisioned that the sensor could be configured as a disposable single-use device for rapid clinical or bedside measurement of heparin in a small, discrete sample. To explore this possibility, an inexpensive, disposable heparin sensor was created by dip-coating a copper wire with the specially formulated heparin-sensing polymeric membrane. Coated wire heparin sensors with a broad range of membrane thicknesses, prepared by repeatedly dipping the wire in the membrane solution for various times, were examined. Data show that increasing the membrane thickness of the sensor to a certain degree (more than 10 microns) enhanced the sensor's potentiometric response to heparin, although the time required to achieve 90% of the steady-state potential change was also prolonged. In addition, increasing membrane thickness also magnified the stirring effect on the sensor's response. In undiluted plasma samples, the coated-wire sensor with an optimized membrane thickness yielded a significant (5 to 30 mV) and reproducible response to heparin in a clinically relevant concentration range (0.5 to 12 units/ml, respectively). The clinical utility of the coated wire heparin sensor was shown using the sensor during protamine titration of heparinized plasma to assess the titration end-point. Preliminary results showed that the titration end-points determined by the heparin sensor strongly correlated with those determined by the activated partial thromboplastin time clotting assay. The overall time requirement to complete the titration process using a set of prefabricated coated wire heparin sensors, however, was less than 3 minutes. Further titration studies using undiluted clinical whole blood samples are in progress.

[Determination of magnolol in cortex Magnoliae officinalis and its processed samples by HPLC and studies on ginger-processed principles]

The experimental result of the quantitative determination of magnolol in Cortex Magnoliae Officinalis and its processed samples by HPLC has shown that the stir-fried sample has the highest content of magnolol among all sample and so does the ginger-fried sample among all ginger-processed samples. As a condiment, ginger can increase the content of magnolol to a certain extent, but the quantity used in processing does not affect the content significantly.