Twenty-minute 50 mg 13C-urea breath test without test meal for the diagnosis of Helicobacter pylori infection in Chinese

BACKGROUND

We have previously shown that the 75 mg 13C-urea breath test without citrate test meal is highly accurate for the diagnosis of Helicobacter pylori infection in Chinese subjects. A lower dose 50 mg 13C-urea breath test protocol with a sampling time at 20 min has not been validated previously.

AIM

To investigate the accuracy of a 20-min 50 mg 13C-urea breath test protocol in Chinese subjects.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. 13C-urea breath test was performed using (a) 75 mg and 50 mg of 13C-urea on two separate days without a test meal, and (b) 50 mg of 13C-urea with 2.4 g citrate as test meal, and compared with the gold standard [rapid urease test (CLO test) and histology]. Baseline, 20-min and 30-min breath samples were collected in all cases.

RESULTS

Two hundred and six patients were tested. The accuracy of the 50 mg 13C-urea breath test (no citrate) at 20 min and 30 min was 98%, comparable to that of the 50 mg 13C-urea breath test with citrate (99.1%) and the 75 mg 13C-urea breath test without citrate (100%).

CONCLUSIONS

A 20-min 50 mg 13C-urea breath test without citrate produced highly accurate results for the diagnosis of Helicobacter pylori infection and is more economical and convenient for the Chinese population.

[Studies on the chemical constituents of the seeds from Artabostrys hexapetalus (Annonaceae)]

AIM

To study the chemical constituents of the seeds from Artabotrys hexapetalus (L.f.) Bhandari (Annonaceae).

METHODS

Various chromatographic techniques were used to separate and purify the constituents. Their structures were elucidated on the physico-chemical properties and spectral data.

RESULTS

Eight compounds were isolated from the seeds of A. hexapetalus. They were identified as four neolignans: isoamericanin A (1), isoamericanol A (2), americanin B (3) and artabotrycinol (4), a semiterpenoid: (R)-artabotriol (5) and others: palmitic acid (6), beta-sitosterol (7) and daucosterol (8).

CONCLUSION

Artabotrycinol (4) and (R)-artabotriol (5) are new compounds. Three other neolignans were isolated from this plant for the first time.

Use of orbicularis oculi muscle flap for undercorrected blepharoptosis with previous frontalis suspension

The frontalis muscle and its fascia are connected with the orbicularis oculi muscle at the level of the eyebrow. Therefore, the superiorly based orbicularis oculi muscle flap, when advanced and attached to the tarsal plate, can dynamically elevate the upper lid and correct blepharoptosis with previous frontalis sling. Six patients with undercorrected blepharoptosis after frontalis sling suspension were included in this study. The superiorly based orbicularis oculi muscle flap was advanced to the tarsal plate in these patients and the redundant portion of the distal flap was resected. Postoperative results were satisfactory after 1-year follow-up.

A rapid method for determining the G+C content of bacterial chromosomes by monitoring fluorescence intensity during DNA denaturation in a capillary tube

A simple and rapid method to determine the G+C content of bacterial chromosomal DNA was developed. It involves determination of Tm by a Light Cycler and calculation of the G+C content by an empirical formula relating Tm to G+C content. Instead of a conventional thermal denaturation method, which monitors the increase of absorbance at 260 nm, thermal denaturation was monitored by the decrease of fluorescence intensity in the presence of SYBR Green 1. In this method, the apparent Tm of DNA was influenced by the concentration of SYBR Green 1, DNA and salt. In addition, when the G+C content was calculated from a linear equation [(mol% G+Cx = mol% G+Cr+1.99(Tmx-Tmr), where x is the unknown organism and y is the reference organism], an error value was introduced among strains with extremely low or high G+C content. Based upon five standards (G+C contents in the range 33-66 mol%), a suitable equation was formulated for the capillary method: mol% G+Cx = mol% G+Cr+1.4652(Tmx-Tmr)+0.0063(Tmx2-Tmr2). To determine the Tm of organisms within this range of G+C contents, Escherichia coli ATCC 11775T was used as a DNA standard and fixed concentrations of SYBR Green 1, sodium citrate and DNA were used. The data from 37 bacterial strains indicated that this equation behaved well. Because it is rapid and simple, it may prove useful for bacterial identification.

Detection of autoantibodies to nuclear antigens by EIA and IF techniques

The detection of antibodies to certain nuclear components has considerable importance in the diagnosis and management of patients with autoimmune diseases. In this study, antibodies to nuclear antigens in 250 positive and negative patient specimens were detected by immunofluorescence (IF) and enzyme immunoassay (EIA). Specimens were tested by three different EIA assays for autoantibodies to SS-A, SS-B, Scl-70 Sm, RNP, Jo-1, ENA, Histone, ss-DNA and ds-DNA and one IF assay for Antinuclear Antibodies (ANA). The majority of positive specimens were also confirmed positive by Western Blot. Ninety-seven percent of IF-ANA positive specimens assayed positive by EIA-ENA assay and only 6% of ENA negative specimens tested positive in IF-ANA assay indicating that EIA-ENA assay is as reliable as IF-ANA for screening patient specimens. Forty-five percent of EIA Jo-1 positive specimens showed negative IF-ANA results indicating that IF-ANA assay is not a reliable method for detection of antibodies to Jo-1. This may be due to the fact that specimens with low titer and sera which are positive for a limited number of specific nuclear antigen(s) cannot produce visible or clear fluorescence patterns and therefore are reported negative by IF-ANA. Our data shows that both methods are reliable for screening purposes, however EIA has greater specificity over IF because the presence or absence of antibody to a specific antigen can be better assessed. Overall, due to higher reproducibility, low cost, antigen specificity, and the nature of EIA, we recommend microtiter-based EIA assays for detection of antibodies to nuclear antigens.

Performance of a fully automated in vitro allergy testing system

BACKGROUND

Since the development of the radioallergosorbent test (RAST) for quantification of allergen-specific IgE, numerous non-radoisotopic methods have been devised which combine the proven cellulose disc technology with enzyme-linked immunoassay methods. The HY.TEC EIA (Hycor Biomedical, Inc. Irvine, CA) was compared with Pharmacia CAP with respect to overall system features and assay performance characteristics.

METHODS

The HY.TEC EIA and Pharmacia CAP were compared with respect to calibrator range, sensitivity, type of detection, type of solid phase, throughput, and mode of operation. To determine the assay sensitivity and specificity for a variety of allergens, a total of 2,447 tests were performed on both CAP and HY.TEC EIA. The samples were scored positive in both cases using a cutoff of 0.35 IU/mL.

RESULTS

The general features of the HY.TEC EIA system are comparable to Pharmacia UniCAP, with the added advantage of higher throughput. Intra-assay precision was 7% and inter-assay precision was 9-15%. Using CAP as a comparative method, HY.TEC EIA has a sensitivity of 94.0% and a specificity of 94.4%.

CONCLUSIONS

The HY.TEC EIA demonstrates excellent agreement with the Pharmacia CAP system in the determination of allergen-specific IgE. With the automation necessary in today's clinical laboratory, we conclude that the HY.TEC EIA is a state-of-the-art tool for the diagnosis of allergic disease.

Diagnosis of motor neuron disease by neurologists: a study in three countries

Ninety four neurologists in the United Kingdom, China, and West Germany responded to two structured questionnaires. The first assessed the diagnostic weighting assigned to a number of symptoms, signs, and clinical investigations ascertained from classical descriptions and case notes of patients with motor neuron disease (MND). The second tested the likelihood and consistency of diagnosis in a series of case summaries representing the clinical data of 10 patients with clinically and pathologically documented motor neuron disease. There was a wide measure of agreement concerning the common clinical features of the disease, especially regarding fasciculation of the tongue, fasciculation associated with weakness seen in more than one limb, and dysphagia. In the case summaries, however, there was clear variation in the ranked likelihood of the diagnosis of MND and in the consistency of diagnostic behaviour in the different groups of neurologists. These findings support the need for internationally agreed criteria in the diagnosis of MND. Any such criteria will need to be tested against a standardised data set to establish their validity.

Phenobarbital monitoring in whole blood with a quantitative noninstrumented test

The AccuLevel phenobarbital test is based on enzyme channeling and immunochromatography. AccuLevel is a noninstrumented test for the quantitative determination of phenobarbital concentration in whole blood. Within-run precision data, with 20 replicates at each of five concentrations, has coefficients of variation (CVs) of 4.7-9.2%. Between-run precision (n = 40) results in a CV of 5.9%. The AccuLevel phenobarbital test is very specific and is unaffected by endogenous substances and blood collection tube anticoagulants. Compared to the Emit method, this test has excellent linear correlation for the quantitation of 104 phenobarbital positive patient samples. Reagents stored at 4-8 degrees C are stable for 15 months with no effect on the assay quantitation. This accurate, precise, and specific test is easily performed in 20 min.

Topoisomerase II activity in a DNA double-strand break repair deficient Chinese hamster ovary cell line

Topoisomerase II activity was measured in wild-type, Chinese hamster ovary K1 cells, and in the DNA double-strand break repair deficient xrs-6 cell line. Total topoisomerase II activity in a high salt, nuclear extract was found to be the same in both cell lines, as measured by decatenation of kinetoplast DNA networks and catenation of plasmid pBR322 DNA. While at low drug concentrations m-AMSA-induced enzyme cutting of nuclear DNA was 25% less in xrs-6 cells, the frequency of DNA breaks at high concentrations of the drug, and thus the frequency of the topoisomerase II enzyme, was the same in both cell lines. Despite the presence of equivalent enzyme levels in both cell lines, the xrs-6 cell line was 3 times more sensitive to drug-induced cytotoxicity. These results may be due to the fact that, as with X-radiation-induced DNA damage, xrs-6 cells are deficient in the capacity to rejoin topoisomerase II-induced DNA double-strand breaks.

Inactivation of aminated horseradish peroxidase by interaction with S-Sepharose

Horseradish peroxidase which had been aminated by periodate oxidation and reductive amination was purified by cation-exchange chromatography on S-Sepharose. Instead of the expected single peak of aminated enzyme, two distinct peaks of protein were eluted from the column. Evaluation of the protein in each of the two distributions showed that peak number 1 had spectral properties and specific activity similar to those of native enzyme. Distribution number 2 had a threefold reduction in the extinction in the Soret region at 404 nm and was completely devoid of enzymatic activity. This inactivation was caused by a specific interaction between the aminated peroxidase and the S-Sepharose matrix, resulting in a displacement of the heme prosthetic group out of its native orientation. The inactivation of the aminated peroxidase was found to be dependent on time, pH, and the support matrix itself. These results indicate that the S-Sepharose and Mono-S resins are not interchangeable, despite the chemical similarities of the two resins.

Clinical features and associations of 560 cases of motor neuron disease

In 560 cases of motor neuron disease, studied retrospectively from their case notes in three teaching centres, the age at onset ranged from 13 to 87 years (mean 56 years), and the mean duration of illness until death was 2.6 years. In the subgroup of the disease presenting with progressive bulbar palsy presenting after age 59 years, there was a previously unrecognised excess of females sufficient to equalize the sex ratio of incidence of the disease in this age group. No potentially causative clinical associations emerged; no relation was noted between occupational exposure to leather products, trauma or surgical procedures and the disease. There was a trend for patients with motor neuron disease to give a history of abstention from alcohol.

Topoisomerase activity in irradiated mammalian cells

The role of topoisomerase enzymes in the response of HeLa S3 cells to ionizing radiation was investigated. Exposure of cells to 100 Gy of X-radiation had no detectable effect either on the total cellular topoisomerase activity as measured by the relaxation of supercoiled plasmid DNA by cell sonicates or on the total cellular topoisomerase II activity as measured by plasmid DNA catenation. Total topoisomerase II activity remained constant for up to 90 min after cell irradiation. The effect of 2 drugs (caffeine and novobiocin) which inhibit topoisomerase II activity on the HeLa cell response to radiation was determined. Both drugs were found to inhibit topoisomerase II in vitro and to inhibit the recovery of nucleoid sedimentation in irradiated cells in vivo to the same extent. Topoisomerase II was inhibited by 50% by exposure to 10 mM caffeine and 0.79 mM novobiocin. At low concentrations neither drug affected the induction frequency, nor the rejoining rate, of DNA double-strand breaks. Caffeine (5 mM) inhibited the short-term recovery of cells from radiation while novobiocin (0.79 mM) had no detectable effect on the capacity of cells to recover from radiation exposure. The results indicate that topoisomerase II is not required for DNA double-strand break rejoining though it could be required for the recovery of DNA coiling in the irradiated cell. If topoisomerase II is involved at all in cell recovery from irradiation, this role does not apparently involve an ATP-dependent enzyme activity.

Comparison of sporadic and familial disease amongst 580 cases of motor neuron disease

A review of 580 hospital case notes of patients with motor neuron disease (MND) revealed 20 families in which more than one case had been reported. For 27 of the cases in these families full medical records were available, and a history of a further 37 affected family members were obtained. The cases in these 20 families are termed familial and the remainder sporadic. Parent to child transmission occurred in 16 of the 20 families of the familial cases, suggesting autosomal dominant inheritance. In three families there was involvement of siblings only, and in one family two cousins were affected. The sex ratio for the documented familial case records seen was 0.8:1 (M/F = 12:15), for the total (documented and historical) it was 1.06:1 (33:31), but in sporadic cases it was 1.6:1 (341:212) and more frequent occurrence of sensory features at presentation was reported in the familial cases (15% in the familial cases and 5% in the sporadic cases). However, none of these differences reached statistical significance. Familial cases also differed from sporadic cases in having a younger age of onset (a mean of 52 years in the familial cases compared with 56 years in the sporadic) and in the shorter median reported duration of illness (1.1 year in the familial cases; 2.6 years in the sporadic). However, in only one fifth of sporadic cases was the age at onset and death known, although this was known for 22 of the 27 familial cases, so that the data on survival and age of onset are too incomplete to test formally.

One-step enzyme immunochromatographic assay for theophylline

The convenience of the previously described enzyme immunochromatography method for visually quantifying theophylline in whole blood has been improved with the development of a one-step protocol. The capillary migration and color generation in the two-step enzyme immunochromatographic assay have been combined into a single step. Ascorbic acid is used as a signal inhibitor to delay enzymatic color product formation until the inhibitor itself is consumed. The concept of internal delay reaction is presented and the mechanism of ascorbate's action as an inhibitor to temporarily delay color generation is described. The internal delay reaction has been applied to a practical one-step quantitative visual enzyme immunochromatographic assay for theophylline in whole blood.

An internal clock reaction used in a one-step enzyme immunochromatographic assay of theophylline in whole blood

We describe the development and performance of a second-generation enzyme immunochromatography method for visually quantifying theophylline in whole blood without the use of instrumentation. We have developed the novel concept of an internal chemical clock reaction to combine the capillary-migration and color-generation protocol of the two-step immunochromatographic assay into a single-step, simultaneous protocol. The two assay components are (a) chromatographic paper to which glucose oxidase (EC 1.1.3.4) and monoclonal antibody to theophylline have been immobilized, and (b) an enzyme reagent consisting of glucose, dicarboxidine, ascorbate, and theophylline-labeled horseradish peroxidase (EC 1.11.1.7). The ascorbate acts as an internal clock by inhibiting premature color formation until the ascorbate has been completely consumed in the peroxidase-mediated reaction. Color is then generated rapidly, producing a clearly visible front on the paper. Performance evaluations of the 20-min one-step assay show very good precision, analytical recovery, specificity, and accuracy. This simplified protocol is reliable and convenient for therapeutic drug monitoring in the physician's office.

An internal clock reaction used in a one-step enzyme immunochromatographic assay of theophylline in whole blood

We describe the development and performance of a second-generation enzyme immunochromatography method for visually quantifying theophylline in whole blood without the use of instrumentation. We have developed the novel concept of an internal chemical clock reaction to combine the capillary-migration and color-generation protocol of the two-step immunochromatographic assay into a single-step, simultaneous protocol. The two assay components are (a) chromatographic paper to which glucose oxidase (EC 1.1.3.4) and monoclonal antibody to theophylline have been immobilized, and (b) an enzyme reagent consisting of glucose, dicarboxidine, ascorbate, and theophylline-labeled horseradish peroxidase (EC 1.11.1.7). The ascorbate acts as an internal clock by inhibiting premature color formation until the ascorbate has been completely consumed in the peroxidase-mediated reaction. Color is then generated rapidly, producing a clearly visible front on the paper. Performance evaluations of the 20-min one-step assay show very good precision, analytical recovery, specificity, and accuracy. This simplified protocol is reliable and convenient for therapeutic drug monitoring in the physician's office.

Differential diagnosis of motoneurone disease from other neurological conditions

Analysis of 422 patients with clinical diagnoses of motoneurone disease (MND), multiple sclerosis, cervical spondylosis with myelopathy, or stroke, from two referral centres, suggested a simple four-step algorithm for diagnosing MND. The algorithm provided a 98% sensitivity (true positive diagnosis) and 86% specificity, and therefore gives a baseline for diagnostic criteria suitable for use in clinical research of MND.

Morbidity and mortality in motor neuron disease: comparison with multiple sclerosis and Parkinson's disease: age and sex specific rates and cohort analyses

The cause of motor neuron disease (MND) remains unknown although recent reports have suggested a possible rise in mortality rate. The present account describes age-specific patterns in morbidity rate and cross-sectional and cohort analyses of mortality rate, and compares these with those in multiple sclerosis and Parkinson's disease. First hospital admission rate for motor neuron disease (a proxy for incidence rates) rose steadily with age in males and females until the age of 75 years or more, but then fell, but only in females. This irregular pattern suggested the possibility of an environmental effect on certain older birth cohorts. The validity of the results was supported by a similar pattern in the two hospital regional authorities studied and the difference between this pattern and that found in multiple sclerosis and Parkinson's disease. Age-specific mortality rates of motor neuron disease between 15 and 64 years for males and females in England and Wales from 1940 to 1982 rose steadily with age. Mortality rates after the age of 65 fell in all female cohorts studied, but only in the earlier male cohorts. Unlike Parkinson's disease there was no strong birth cohort effect. However an analysis of Office of Population Censuses and Surveys (Registrar General) reports has revealed a slight increase in the age-specific mortality rate in both males and females aged 65 and over for successive birth cohorts born since 1900. Neither changes in ICD coding or in diagnostic habits could account for this pattern, which differed from that seen in Parkinson's disease. No such effect was seen in multiple sclerosis.

New sequential external counterpulsation for the treatment of acute myocardial infarction

Over a period of 6 years, 52 patients with acute myocardial infarction (AMI) were treated with sequenced external counterpulsation (SECP). Of the 23 patients who experienced severe chest pain, 22 had complete relief within 30 min of SECP, and 31 of the 52 patients showed remarkable improvement in their electrocardiogram after the first hour of treatment. Fifteen patients were studied using the 35-lead ST segment elevation-mapping method. sigma ST and NST, indicators of infarct size, showed decreasing trends in seven patients treated with SECP for a period of 6 days, whereas sigma ST and NST of the control group of eight patients increased during the same period. Our hemodynamic data indicate that in four of five patients with AMI and left heart failure, the central venous pressure and cardiac output increased after SECP, whereas the pulmonary wedge pressure decreased. Measurements of the P-wave terminal force of lead V1 also demonstrated that the application of SECP can improve left ventricular function in a majority of patients with AMI.

Automated fluorometer/photometer system for homogeneous immunoassays

A fully automated bench-top clinical analyzer (OPTIMATE TM; Ames/Gilford) performs homogeneous fluorescent immunoassays, colorimetric immunoassays, and determinations of routine blood analytes; drugs, enzymes, metabolites, specific proteins, and hormones in serum. Unique features include a combination fluorescence/absorbance aspirating thermocuvette, a photon-counting fluorometer/photometer, a multi-reagent distribution valve to dispense as many as three reagents plus buffer, and a user-replaceable programmable memory cartridge for software updates. We have evaluated the performance of OPTIMATE substrate-labeled fluorescent immunoassays for gentamicin, tobramycin, amikacin, theophylline, phenytoin, phenobarbital, primidone, carbamazepine, and quinidine with this automated system. A sample throughput of 92 samples per hour is achieved by reading fixed-point fluorescence results every 39 s after an initial 4-min reaction period. Precision studies indicate typical CVs of less than or equal to 6% for mid-range controls. Standard curves can be reused for as long as two weeks before recalibration. With clinical samples, results by the OPTIMATE procedure correlated well (r greater than or equal to 0.97) with those by a reference method.

Automated fluorometer/photometer system for homogeneous immunoassays

A fully automated bench-top clinical analyzer (OPTIMATE TM; Ames/Gilford) performs homogeneous fluorescent immunoassays, colorimetric immunoassays, and determinations of routine blood analytes; drugs, enzymes, metabolites, specific proteins, and hormones in serum. Unique features include a combination fluorescence/absorbance aspirating thermocuvette, a photon-counting fluorometer/photometer, a multi-reagent distribution valve to dispense as many as three reagents plus buffer, and a user-replaceable programmable memory cartridge for software updates. We have evaluated the performance of OPTIMATE substrate-labeled fluorescent immunoassays for gentamicin, tobramycin, amikacin, theophylline, phenytoin, phenobarbital, primidone, carbamazepine, and quinidine with this automated system. A sample throughput of 92 samples per hour is achieved by reading fixed-point fluorescence results every 39 s after an initial 4-min reaction period. Precision studies indicate typical CVs of less than or equal to 6% for mid-range controls. Standard curves can be reused for as long as two weeks before recalibration. With clinical samples, results by the OPTIMATE procedure correlated well (r greater than or equal to 0.97) with those by a reference method.

Homogeneous substrate-labeled fluorescent immunoassay for carbamazepine

Carbamazepine is an anticonvulsant drug useful in the management of epilepsy. Because of the narrow therapeutic range, serum carbamazepine monitoring is useful for ensuring adequate drug therapy without toxicity. We report the development of a homogeneous substrate-labeled fluorescent immunoassay for carbamazepine in human serum. A carbamazepine fluorogenic reagent (FR) has been synthesized. Upon hydrolysis by beta-galactosidase, the nonfluorescent FR produces a fluorescent product. This enzymic hydrolysis sin inhibited when the FR binds with antibody against carbamazepine. The inhibition is relieved when carbamazepine competes with FR for available antibody binding sites. Thus, increasing levels of carbamazepine result in increasing levels of fluorescence that can be conveniently monitored with any conventional fluorometer. For low, medium, and high control sera (4, 12, and 16 micrograms carbamazepine/ml), the within-run coefficient of variation for the assay is 5.5%, 1.6%, and 2.9%, respectively, while the respective between-run coefficients of variation are 3.5%, 1.9%, and 2.3%. Fifty-three clinical serum samples were assayed by the SLFIA, gas chromatography (GC), high pressure liquid chromatography (HPLC), and an enzyme immunoassay method. The SLFIA method compares favorably with the HPLC technique (r - 0.97, slope = 1.10, y-intercept = 1.21), the enzyme immunoassay (r = 0.98, slope = 1.07, y-intercept = 0.82), and the GC method (r = 0.95, slope = 1.01, y-intercept = -0.03).