Delta15N of soil N and plants in a N-saturated, subtropical forest of southern China

We investigated the delta(15)N profile of N (extractable NH(4)(+), NO(3)(-), and organic N (EON)) in the soil of a N-saturated subtropical forest. The order of delta(15)N in the soil was EON > NH(4)(+) > NO(3)(-). Although the delta(15)N of EON had been expected to be similar to that of bulk soil N, it was higher than that of bulk soil N by 5 per thousand. The difference in delta(15)N between bulk soil N and EON (Delta(15)N(bulk-EON)) was correlated significantly with the soil C/N ratio. This correlation implies that carbon availability, which determines the balance between N assimilation and dissimilation of soil microbes, is responsible for the high delta(15)N of EON, as in the case of soil microbial biomass delta(15)N. A thorough delta(15)N survey of available N (NH(4)(+), NO(3)(-), and EON) in the soil profiles from the organic layer to 100 cm depth revealed that the delta(15)N of the available N forms did not fully overlap with the delta(15)N of plants. This mismatch in delta(15)N between that of available N and that of plants reflects apparent isotopic fractionation during N uptake by plants, emphasizing the high N availability in this N-saturated forest.

5-HT 3 receptors mediate the time-dependent vagal afferent modulation of nociception during chronic food allergen-sensitized visceral hyperalgesia in rats

Converging lines of evidence demonstrate a vagally mediated antinociceptive pathway in animals undergoing acute visceral insults, the contribution of this system to visceral pain following chronic noxious stimuli is unknown. 5-HT(3) receptor (5-HT(3)Rs) on spinal afferents are crucially involved in nociceptive processing, the role of 5-HT(3)Rs on vagal afferents is unclear. The aim of the present study was to determine the contribution of vagal afferents to visceral nociception in rats undergoing chronic luminal allergen stimulation and whether it involves vagal 5-HT(3)Rs. Sensitized rats received chicken egg albumin (EA, 1 mg mL(-1)) in drinking water for 2 weeks (day 1-14). Visceromotor response (VMR) to colorectal distension [colorectal distension (CRD), 60 mmHg] and the levels of mRNA encoding 5-HT(3)R (including 3A and 3B subunits) in the nodose ganglia (NG) were evaluated on day 2, 4, 8 and 15. Chronic EA challenge induced gradually increased visceral nociception, with a peak on day 15. Subdiaphragmatic vagotomy or functional deafferentation with capsaicin abolished this time-dependent manner, inducing hyperalgesia from day 2, lasting to day 15. Intraluminal infusion of a 5-HT(3)R antagonist (granisetron), whether alone or infused after local mucosa anaesthetic with 1% lidocaine, mimicked the effects of vagotomy. The mRNA levels for 5-HT(3B) or 5-HT(3A) subunit in the NG showed an opposite time-course to that of visceral pain, which increased from day 2, then decreased gradually to levels lower than those of controls. Our results demonstrate a time-dependent vagal afferent modulation of chronic allergen-sensitized visceral hyperalgesia, which may involve a 5-HT(3)R pathway.

A simple method for fixation and microdissection of frozen fresh tissue sections for molecular cytogenetic analysis of cancers

Microdissection has been widely used for procuring DNA from specific microscopic regions of formalin fixed, paraffin embedded tissue sections. We have developed a method for fixation and microdissection of frozen fresh biopsy tissue sections. Five micrometer frozen fresh tissue sections were fixed with ethanol and stored at room temperature. Well defined regions from hematoxylin and eosin (H & E) stained or unstained sections were briefly steamed and microdissected using a needle. The dissected tissue was digested with proteinase K and DNA was isolated. Whole genome amplifications were obtained by degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) from these samples. The reliability of this technique was demonstrated by comparing conventional comparative genomic hybridization (CGH) with DOP-PCR-CGH. The advantages of this method are that frozen fresh sections can be fixed easily and stored for more than 4 years, it is easy to microdissect and pick-up very minute regions (0.1 mm(2)), and it is rapid; microdissection and purification can be accomplished within 3 h. Using DNA from microdissected sections, DOP-PCR-CGH revealed genetic abnormalities more accurately than conventional CGH. Although this novel method was demonstrated using DOP-PCR-CGH, we believe that it will be useful for other genetic analyses of specific small regions and cell populations. We also observed whether storage time, H & E staining and crude DNA extracts affected the quality of amplified DNA. DNA integrity was maintained for at least 49 months in ethanol fixed sections that were stored at room temperature, but DNA was gradually degraded after one month if the ethanol fixed sections had been H & E stained and stored. When crude DNA extracts from H & E stained sections were used, the size of the DOP-PCR product was reduced. Our study suggests that ethanol fixed tissue sections may be stored at room temperature for at least 4 years without DNA degradation, the H & E stains may not affect the quality of amplified DNA, but H & E or other components in the staining process may reduce the size of DOP-PCR product, which is critical for the quality of CGH hybridization.

The Frequency of Proliferative Stromal Cells in Adipose Tissue Varies Between Inbred Mouse Strains

Stromal cells derived from adipose tissue (ASCs) can proliferate as undifferentiated cells with a fibroblast-like morphology in cell culture, or can be induced to differentiate into a variety of cell types including, adipipogenic, myogenic, neurogenic, osteogenic, chondrogenic and hepatic cells. There is increasing interest to understand the factors controlling the proliferation of ASCs since these cells might provide a readily available source of autologous stem/progenitor cells for cell therapy applications. To explore potential genetic factors that modify the properties of ASCs, we tried to identify relevant properties of ASCs that differ between inbred mouse strains. Plating cells in a modified colony forming assay indicates that the percentage of high proliferative cells among ASCs differs more than 2-fold between 129x1/svj and C57Bl/6J mice. The identification of genetic factors affecting the proliferative capacity of stem cell populations could improve the efficacy of cell therapy.

Modification of an effector strain for replacement therapy of dental caries to enable clinical safety trials

AIMS

To construct a genetically modified strain of Streptococcus mutans for dental caries prevention. The strain has significantly reduced cariogenicity owing to a deletion of the entire open reading frame for lactate dehydrogenase, and has excellent colonization potential through the production of a natural antibiotic called mutacin 1140. For use in human clinical trials, additional mutations were introduced to enable rapid elimination of the strain in case of adverse side effects and to increase genetic stability.

METHODS

Deletion mutations were introduced into the dal gene for d-alanine biosynthesis and the comE gene for genetic transformation. The resulting strain, A2JM, was tested for dependence on exogenous d-alanine and its ability to be eradicated from colonized rats. The strain was also tested for its ability to exchange DNA with another strain of S. mutans in in vitro and in vivo models.

CONCLUSIONS

A2JM was completely dependent on exogenous d-alanine, but could colonize the oral cavity of rats in low numbers in the absence of dietary d-alanine. Results indicated that A2JM can scavenge d-alanine from other plaque bacteria. Lowering of the total oral bacterial load through daily application of chlorhexidine enabled virtually complete eradication of A2JM. The introduction of the comE gene did not significantly decrease the transformability of A2JM in in vitro or in vivo models. The addition of a deletion in the comE gene does, nonetheless, provide additional safety as it has a very low reversion frequency.

SIGNIFICANCE AND IMPACT OF THE STUDY

Based on the safety and efficacy profiles established in vitro and in animal models, A2JM appears suitable for safe use in human clinical trials.

Metabolic syndrome, its preeminent clusters, incident coronary heart disease and all-cause mortality--results of prospective analysis for the Atherosclerosis Risk in Communities study

OBJECTIVE

To investigate the prospective association between Metabolic Syndrome (MetS) and coronary heart disease (CHD) and all-cause mortality.

SUBJECTS AND DESIGN

A bi-racial cohort of 14 699 middle-aged Americans from the Atherosclerosis Risk in Communities study were followed for the development of new CHD and death over a period of 9 years. MetS, using the original ATP-III criteria, was defined as having at least three of the following components: elevated blood pressure (BP), elevated plasma glucose, elevated blood triglyceride (TG), increased waist circumference, and low HDL cholesterol (HDL-c). Incident CHD cases included hospitalized myocardial infarction (MI), fatal CHD, revascularization procedures, and silent MI as detected by EKG.

RESULTS

The prevalence of the MetS at baseline was 29%, 30%, 40% and 26% among CHD-free white women, white men, black women, and black men, respectively. There were 1018 incident CHD cases and 1039 deaths. The relative risk (RR) and 95% confidence interval (CI) of incident CHD associated with MetS was 2.46 (1.99, 3.03) for women and 1.86 (1.59, 2.18) for men. Clear dose-response relationship between the number of MetS components and incidence of CHD was found (P for linear trend <0.001). The following three clusters of MetS components posed the highest risk for CHD: (i) the elevated BP and glucose and low HDL-c group [RR = 5.68 (3.44, 9.37)]; (ii) the elevated BP and glucose and TG group [RR = 5.08 (2.96, 8.70)]; and (iii) the elevated BP and TG and low HDL-c group [RR = 3.98 (2.75, 5.77)]. When all five components co-existed, the risk was the highest [RR = 6.24 (4.65, 8.36)]. Similar results with attenuated RR were found for all-cause mortality.

CONCLUSIONS

Individuals, especially women, with the MetS have significantly higher risk of developing CHD. The riskiest combination is high-BP and glucose clustered with low HDL-c or high TG. These data highlight the importance of targeting MetS in the prevention of CHD and premature death.

Headache, cerebrovascular symptoms, and stroke: the Atherosclerosis Risk in Communities Study

OBJECTIVE

To evaluate the occurrence of stroke/TIA symptoms and ischemic stroke events among those with a lifetime history of migraine or other headaches with some migraine features in a biracial cohort of older adults.

METHODS

Participants were 12,750 African-American and white men and women from the Atherosclerosis Risk in Communities Study (1993 to 1995). The participants were queried about their lifetime headache history and characterized using modified International Headache Society diagnostic criteria. Stroke/TIA symptoms were classified using a computerized diagnostic algorithm, and ischemic stroke events were identified and validated using medical records. Multivariate logistic regression was used to assess the relationship between headache types and stroke/TIA symptoms and ischemic stroke events.

RESULTS

Migraine with aura was strongly associated with stroke symptoms (odds ratio [OR] 5.46, 95% CI: 3.64 to 8.18), TIA symptoms (OR 4.28, 95% CI: 3.02 to 6.08), and verified ischemic stroke events (OR 2.81, 95% CI: 1.60 to 4.92). Similarly, other headaches with aura were significantly associated with stroke symptoms (OR 3.68, 95% CI: 2.26 to 5.99) and TIA symptoms (OR 4.53, 95% CI: 3.08 to 6.67). In contrast, the associations for migraine without aura and other headaches without aura were not as consistent or robust.

CONCLUSIONS

Migraines and other headaches, particularly those accompanied by aura, were associated with an increased occurrence of stroke/TIA symptoms and ischemic stroke events.

Novel insight into VOC removal performance of photocatalytic oxidation reactors

A general model has been developed for analyzing the removal of volatile organic compounds (VOCs) by photocatalytic oxidation (PCO) reactors, taking into consideration of the photocatalytic (surface) reaction and the convective mass transfer coefficients including allowance for their spatial dependence. On this basis, a novel insight into VOC removal performance of PCO reactors is presented. The key parameter for evaluating PCO reactor VOC removal performance is the number of the mass transfer unit (NTU(m)), which is shown to be a simple linear product of three dimensionless parameters: the ratio of the reaction area to the cross-sectional area of the flow channel (A*), the Stanton number of mass transfer (St(m)), and the reaction effectiveness (eta). The A* represents the geometric and structural characteristic of a PCO reactor. The St(m) shows the synergistic degree of alignment between the fluid and mass flow fields, and reflects the convective mass transfer rate of the reactor. The eta, describes the relative intensity between the PCO reaction rate and the mass transfer rate. By using the relationship and the parameters, the influence of various factors on the VOC removal performance, the bottleneck for improving the performance and design of a PCO reactor can be determined. Three examples are used to illustrate the application of our proposed model. It is found that the VOC removal bottleneck is the reaction rate for honeycomb type reactor, while mass transfer rate for light-in-tube type reactor. With six fins the fractional conversion of a light-in-tube reactor increases about 70% relative to the one without any fins.

PRACTICAL IMPLICATIONS

Indoor air quality problem caused by volatile organic compounds (VOCs) have annoyed people for many years. Photocatalytic oxidation (PCO) appears to be a promising technique for destroying VOCs in indoor air. With the model and the novel insight presented in this paper, the influence of various factors on the VOC removal performance can be determined. And the bottleneck for improving the performance of a PCO reactor can be easily identified. These are helpful for designing high performance PCO reactors and optimizing their operative performance.

Fine mapping of 10q and 18q for familial Alzheimer's disease in Caribbean Hispanics

Familial Alzheimer's disease (AD [MIM 104300]) has been a focus of intense investigation, primarily in Caucasian families from Europe and North America families. Although the late-onset form of familial AD, beginning after age 65 years, has been linked to regions on chromosomes 10q and 12p, the specific genetic variants have not yet been consistently identified. Using a unique cohort of families of Caribbean Hispanics ancestry, we screened the genome using 340 markers on 490 family members from 96 families with predominantly late-onset AD. We observed the strongest support for linkage on 18q (LOD=3.14). However, 17 additional markers (chromosomes 1-6, 8, 10, 12, and 14) exceeded a two-point LOD score of 1.0 under the affecteds-only autosomal dominant model or affected sibpair model. As we previously reported the fine-mapping effort on 12p showing modest evidence of linkage, we focused our fine-mapping efforts on two other candidate regions in the current report, namely 10q and 18q. We added 31 family members and eight additional Caribbean Hispanic families to fine map 10q and 18q. With additional microsatellite markers, the evidence for linkage for 18q strengthened near 112 cM, where the two-point LOD score for D18S541 was 3.37 and the highest NPL score in that region was 3.65 (P=0.000177). This narrow region contains a small number of genes expressed in the brain. However, at 10q (134-138 cM), the NPL score decreased from 3.15 (P=0.000486) to 2.1 (P=0.0218), but two broad peaks remained overlapping with previously reported peaks. Our results provide modest support for linkage on 10q and 12p in this cohort of Caribbean Hispanic families with familial Alzheimer's disease, and strong evidence for a new locus on 18q.

Prevalence of diabetes and impaired fasting glucose in the Chinese adult population: International Collaborative Study of Cardiovascular Disease in Asia (InterASIA)

AIMS/HYPOTHESIS

To estimate the prevalence of diagnosed and undiagnosed diabetes and impaired fasting glucose in the general adult population of China.

METHODS

The International Collaborative Study of Cardiovascular Disease in ASIA, conducted from 2000 to 2001, included a nationally representative sample of 15 540 adults, aged 35 to 74 years. An overnight fasting blood specimen was collected to measure serum glucose and information on history of diabetes and use of hypoglycaemic medications was obtained by a standard questionnaire. Undiagnosed diabetes (fasting glucose > or =7.0 mmol/l) and impaired fasting glucose (6.1-6.9 mmol/l) were defined using the American Diabetes Association criteria.

RESULTS

Prevalence of self-reported diagnosed diabetes, undiagnosed diabetes, and impaired fasting glucose in Chinese adults were 1.3%, 4.2%, and 7.3%, respectively. Overall, 5.2% or 12.7 million men and 5.8% or 13.3 million women in China aged 35 to 74 years had diabetes (self-reported diagnosis plus undiagnosed diabetes). The age-standardized prevalence of diabetes was higher in residents of northern compared to southern China (7.4% vs 5.4%, p<0.001) and in those living in urban compared to rural areas (7.8% vs 5.1%, p<0.001).

CONCLUSIONS/INTERPRETATION

Our results show that the prevalence of diabetes in the adult population in China is much higher than previously reported. Three out of every four diabetes patients are undiagnosed, indicative of a lack of population-based screening programmmes and a relatively rapid and recent increase in incidence of diabetes. These results indicate that diabetes has become a major public health problem in China and underscore the need for national strategies aimed at prevention and treatment of diabetes.

Nesidioblastosis coexisting with islet cell tumor and intraductal papillary mucinous hyperplasia

A coexisting of intraductal papillary mucinous hyperplasia (IPMH) and islet cell tumor with nesidioblastosis of the pancreas in a 51-year-old man is reported. All of the clinical data indicated an insulinoma. A distal pancreatectomy was performed. A discrete mass measuring 1.9 x 2.0 cm was grossly identified in the tail of the pancreas. There were no other gross lesions. An islet cell tumor with nesidioblastosis was confirmed by immunostains and ultrastructural study. In addition, an IPMH was found that involved mainly branches of the pancreatic duct. The islet cell tumor and IPMH were topographically separated; however, there was a histologically intimate relationship between the nesidioblastosis and the IPMH. These findings indicate that the IPMH may have derived from autocrine and paracrine influences on the existing duct epithelial cells. To the best of our knowledge, this is the first report of nesidioblastosis coexisting with islet cell tumor and IPMH.

[Process of recovery of peristaltic function at anastomotic stoma after dismembering pyeloplasty in rabbits]

OBJECTIVE

To study the process of recovery of peristaltic function at anastomotic stoma after dismembering pyeloplasty in rabbits.

METHODS

An animal model of obstructive hydronephrosis was made with 32 New Zealand rabbits. These rabbits were divided into four groups to be examined within the first, second, third, and fourth week respectively after a dismembering pyeloplasty was performed on them, eight rabbits in each group. Thirty-two normal New Zealand rabbits were divided into four corresponding control groups as controls. Pressures of the renal pelvis and upper ureter were measured, electromyogram was recorded, and histological examination was made to the tissue of anastomotic stoma before and after the operation.

RESULTS

In the normal control rabbits, the resting pressure was (10.8 +/- 1.3) mm Hg, contraction amplitude was (1.6 +/- 0.4) mm Hg, pulse amplitude of EMG was (0.39 +/- 0.10) mV, and pulse frequency was (5.4 +/- 1.0)/min in the renal pelvis; and the resting pressure was (11.7 +/- 1.7) mm Hg, contraction amplitude was (1.8 +/- 0.5) mm Hg, pulse amplitude of EMG was (0.38 +/- 0.08) mV, pulse frequency was (5.3 +/- 0.9)/min in the upper ureter. Within the first week after operation, the resting pressure of renal pelvis was (14.4 +/- 1.3) mm Hg, significant higher than normal (P < 0.05), the contraction amplitude of renal pelvis was (1.1 +/- 0.4) mm Hg, lower than normal (P < 0.05); the pulse amplitudes of EMG in renal pelvis (0.19 +/- 0.05) mV and in upper ureter (0.26 +/- 0.04) mV were lower than normal (P < 0.05). A thin layer of mucosa was seen covering the anastomotic stoma. In the second week after operation, no statistical difference was observed in resting pressure, contraction amplitude, amplitude of EMG, and frequency of EMG in renal pelvis between the experimental rabbits and the controls (P > 0.05). Newborn smooth muscle cells were seen running through the anastomotic stoma, and close contact was observed among the cells. Within the third week after operation, the pressures and EMG in renal pelvis and in upper ureter were not significantly different from those in normal rabbits (P > 0.05). Nerve endings could be seen near the anastomotic stoma. Within the fourth week after operation, newborn muscle cells became mature and arranged regularly, and contacted each other closely.

CONCLUSION

Within the first week after the dismembering pyeloplasty, no peristalsis runs through the anastomotic stoma, and the renal pelvic resting pressure increases. Within the second week after the operation, the newborn smooth muscle cells at the anastomotic stoma begin to exercise their contractive and conductive functions. Peristalsis begins to run through the anastomotic stoma. Within the third after the operation, the peristaltic function basically recovers to normal.

DNA damage in the nucleosome core is refractory to repair by human excision nuclease

To investigate the effect of nucleosomes on nucleotide excision repair in humans, we prepared a mononucleosome containing a (6-4) photoproduct in the nucleosome core and examined its repair with the reconstituted human excision nuclease system and with cell extracts. Nucleosomal DNA is repaired at a rate of about 10% of that for naked DNA in both systems. These results are in agreement with in vivo data showing a considerably slower rate of repair of overall genomic DNA relative to that for transcriptionally active DNA. Furthermore, our results indicate that the first-order packing of DNA in nucleosomes is a primary determinant of slow repair of DNA in chromatin.

Improving degenerate oligonucleotide primed PCR-comparative genomic hybridization for analysis of DNA copy number changes in tumors

Combining degenerate oligonucleotide-primed PCR (DOP-PCR) with comparative genomic hybridization (CGH) has made it possible to analyze genomic changes in single cells. Although DOP-PCR-CGH methodology has been reported, the reproducibility of the method has been uncertain. We have developed a reproducible DOP-PCR-CGH protocol by systematically evaluating different labeling methods (including nick translation, PCR incorporation, and random-primed labeling) and different hybridization mixtures (including amplified test DNA vs. amplified reference DNA, termed homo-hybridization; and amplified test DNA vs. unamplified reference DNA or vice versa, termed hetero-hybridization). We have analyzed DNA samples obtained from 16 tissue sources including fresh/frozen normal and tumor samples, formalin fixed and paraffin embedded tumor tissue, and tumor cell lines by using differently labeled probes and hybridization combinations, and we calculated the corresponding rate (CR) of DOP-PCR-CGH with standard CGH. We found that homo-hybridization produced reproducible results with high CRs as compared to standard CGH (91-100% CR, mean 97%); In contrast, hetero-hybridization failed to generate reproducible hybridization with low CRs (57-97% CR, mean 80%; chi(2) = 1245.8, P<0.0001), high background, uneven hybridization, and false deletions or amplifications. In addition, our improved DOP-PCR protocol raised the amplification efficiency at least five times as compared to previously reported protocols, allowing for the detection of genomic imbalances in as little as 12.5 pg of starting DNA. In conclusion, the DOP-PCR-CHG homo-hybridization method, especially when combined with labeling by nick translation, is reliable and reproducible. The method can be used in screening for genomic imbalances using minute amounts of tumor DNA, thereby facilitating CGH application. Genes Chromosomes Cancer 28:395-403, 2000.

Identification of a fourth subunit of mammalian DNA polymerase delta

A 12-kDa and two 25-kDa polypeptides were isolated with highly purified calf thymus DNA polymerase delta by conventional chromatography. A 16-mer peptide sequence was obtained from the 12-kDa polypeptide which matched a new open reading frame from a human EST () encoding a hypothetical protein of unknown function. The protein was designated as p12. Human EST was identified as the putative human homologue of Schizosaccharomyces pombe Cdm1 by a tBlastn search of the EST data base using S. pombe Cdm1. The open reading frame of human EST encoded a polypeptide of 107 amino acids with a predicted molecular mass of 12.4 kDa, consistent with the experimental findings. p12 is 25% identical to S pombe Cdm1. Both of the 25-kDa polypeptide sequences matched the hypothetical KIAA0039 protein sequence, recently identified as the third subunit of pol delta. Western blotting of immunoaffinity purified calf thymus pol delta revealed the presence of p125, p50, p68 (the KIAA0039 product), and p12. With the identification of p12 mammalian pol delta can now be shown to consist of four subunits. These studies pave the way for more detailed analysis of the possible functions of the mammalian subunits of pol delta.

Evidence that DNA polymerase delta isolated by immunoaffinity chromatography exhibits high-molecular weight characteristics and is associated with the KIAA0039 protein and RPA

DNA polymerase delta, the key enzyme for eukaryotic chromosomal replication, has been well characterized as consisting of a core enzyme of a 125 kDa catalytic subunit and a smaller 50 kDa subunit. However, less is known about the other proteins that may comprise additional subunits or participate in the macromolecular protein complex that is involved in chromosomal DNA replication. In this study, the properties of calf thymus pol delta preparations isolated by immunoaffinity chromatography were investigated. It is demonstrated for the first time using highly purified preparations that the pol delta heterodimer is associated with other polypeptides in high-molecular weight species that range from 260000 to >500000 in size, as determined by FPLC gel filtration. These preparations are associated with polypeptides of ca. 68-70, 34, 32, and 25 kDa. Similar findings were revealed with glycerol gradient ultracentrifugation. The p68 polypeptide was shown to be a PCNA binding protein by overlay methods with biotinylated PCNA. Protein sequencing of the p68, p34, and p25 polypeptide bands revealed sequences that correspond to the hypothetical protein KIAA0039. KIAA0039 displays a small but significant degree of homology to Schizosaccharomyces pombe Cdc27, which, like Saccharomyces cerevisiae Pol32p, has been described as the third subunit of yeast pol delta. These studies provide evidence that p68 is a subunit of pol delta. In addition, the p68-70 and p32 polypeptides were found to be derived from the 70 and 32 kDa subunits of RPA, respectively.

[Separation and determination of the ingredients of cold medicines by capillary electrophoresis with amperometric detection]

Determination and separation of three ingredients--chlorphenamine maleate, acetaminophen and vitamin C in cold medicines by capillary electrophoresis with amperometric detection were carried out. The effects of detection potential and organic modifier were extensively investigated. Separation efficiency could be improved by adding 1, 2-propanediol into buffer. On optimizing condition, chlorphenamine maleate, acetaminophen and vitamin C were separated satisfactorily and eluted within 12 min. The detection limits were 0.02, 0.08 and 0.01 mg/L respectively. The ingredients in several cold medicines were detected successfully. The recoveries of the samples were 94.2%-102.8%. The method is simple, rapid and highly reliable for routine analysis.

[Determination of epinephrine, chlorpromazine and promethazine by capillary electrophoresis with scanning voltammetric detector]

With a self-constructed electrochemical detection system, the determination of epinephrine, chlorpromazine and promethazine has been studied by using capillary electrophoresis with scanning voltammetric detector. Scanning potential generation and data acquisition were carried out with D/A and A/D converter board that mounted on a 486DX66 computer. A complex software, which was written by authors in BORLAND C++, was serve to data acquisition, abstraction of three-dimension data, display and print of the electrophorograms. Using a 25 microns x 70 cm fused-silica capillary, the optimum conditions for separation and detection of titled drugs are 10 mmol/L K2HPO4 + H3PO4 (pH 3.0) running electrolyte, 20 kV separation voltage, hydrodynamic injection 10 s at 20 cm height, scanning potential from +0.4 to +1.0 V vs. SCE. With the optimizing condition, the separation of titled drugs is satisfactory, and good reproducibility and low limit are obtained. In this study, all experiments are carried out under air-conditioning (18 degrees C) and constant humidity (relative humidity 50%). In comparison to amperometric detection, scanning voltammetric detection has the advantages of minimizing fouling of the working electrode surface, and direct identification of unknown chemicals by voltammetric curves.