[Evaluation of severity and prognosis of acute pancreatitis by CT severity index and modified CT severity index]

Objectives: To explore the role of computed tomography (CT) severity index (CTSI) and modified CT severity index (MCTSI) in assessing the severity of acute pancreatitis (AP) under the revised Atlanta classification (RAC) and predicting the clinical prognosis. Methods: Based on the prospectively entered AP database, the clinical data of consecutive adult AP inpatients admitted to the Department of Gastroenterology of the First Affiliated Hospital of Nanchang University from January 2012 to December 2020 were retrospectively screened. The imaging data were independently evaluated by two radiologists and entered to the database to calculate the CTSI and MCTSI scores. Their relationship with the difference of RAC severity grade and clinical prognosis was analyzed. Compared with Acute Physiology and Chronic Health Assessment Ⅱ (APACHE Ⅱ) score, the receiver operating characteristic curve was used to evaluate the predictive value of CTSI and MCTSI scores for persistent organ failure and infectious pancreatic necrosis (IPN). Results: A total of 2 612 patients with AP, aged (50±15) years, were included in the study, including 1 547 males (59.2%) and 1 065 females (40.8%). According to RAC standard, AP was divided into 699 cases (26.8%) of mild pancreatitis (MAP), 1 098 cases (42.0%) of moderately severe pancreatitis (MSAP), and 815 cases (31.2%) of severe pancreatitis (SAP). MCTSI judged AP severity similarly to RAC, with 668 cases of MAP (25.6%), 1 207 cases of MSAP (46.2%) and 737 cases of SAP (28.2%), while CTSI judged SAP patients less(400 cases, 15.3%). The severity of AP determined by CTSI and MCTSI scores was significantly correlated with clinical prognosis (r=0.06-0.43, all P<0.05). Compared with APACHE Ⅱ score, CTSI had the highest area under the curve (AUC) for predicting IPN (AUC=0.85, 95%CI: 0.83-0.87), followed by MCTSI (AUC=0.82, 95%CI: 0.80-0.85). APACHE Ⅱ was more accurate in predicting persistent organ failure than CTSI and MCTSI scores,with AUC of 0.73 (95%CI: 0.71-0.75), 0.72 (95%CI: 0.70-0.74) and 0.72 (95%CI: 0.70-0.74), respectively. Conclusions: AP severity judged by MCTSI is consistent with RAC, and SAP patients judged by CTSI are less than RAC. CTSI and MCTSI are significantly correlated with clinical prognosis. CTSI and MCTSI have higher accuracy in predicting IPN, but lower accuracy in predicting persistent organ failure than APACHE Ⅱ.

[Follow-up study on natural course changes of obstructive sleep apnea hypopnea syndrome among young and middle aged patients]

Objective: To explore the natural course of obstructive sleep apnea-hypopnea syndrome (OSAHS) and its associated factors in young and middle-aged patients with OSAHS. Methods: A total of 52 young and middle-aged OSAHS patients were recruited in this study from West China Hospital of Sichuan University. All patients were performed twice overnight polysomnography (PSG) examinations. At the baseline, patients underwent the first PSG and clinical evaluation from September 2009 to September 2017 and the patients received the second PSG from January 2017 to January 2019. During the follow-up period, these patients had no treatment. All patients were categorized into two groups including mild-to-moderate [5/h≤ apnea-hypopnea index (AHI)<30/h] group and severe (AHI ≥ 30/h) group according to the baseline AHI value. Differences in the clinical characteristics and PSG variables between baseline and follow-up were compared in two groups separately using t-tests or Mann-Whitney U test. The general linear correlation analysis was used to explore the factors related to the severity of OSAHS including AHI, the mean oxyhemoglobin saturation and the minimal oxyhemoglobin saturation during the follow-up period. Results: This study recruited 28 OSAHS patients in mild-to-moderate group [mean age, (39.7±10.2) y] and 24 patients in severe group [mean age, (41.0±7.1) y]. Compared to the baseline, there was a significant increase in AHI value [(45.0±25.3) vs (33.6±27.3)/h, P<0.001] in all OSAHS patients. Notably, the increase of AHI was more significant in the mild-to-moderate OSAHS group [(32.1±22.2) vs (13.6±8.7)/h, P<0.05] but not in severe OSAHS patients [(60.7±19.5) vs (58.0±21.5)/h, P>0.05]. A person correlation analysis revealed that the AHI value was positively related to the age (r=0.531, P=0.004) in mild-to-moderate OSAHS patients. Conclusion: The severity of OSAHS is increased with the age in young and middle-aged patients with mild-to-moderate OSAHS, but not in those with severe OSAHS.

[Associations between objective sleepiness and cognition function before and after CPAP in obstructive sleep apnea patients]

Objective: To examine the association between objective sleepiness and neurocognitive function before and after continuous positive airway pressure (CPAP) in obstructive sleep apnea (OSA) patients. Methods: A total of 53 patients with overnight polysomnography (PSG) determined moderate-to-severe OSA (apnea hypopnea index (AHI) ≥15 events/h) and with overnight CPAP therapy from West China Hospital, Sichuan University within the period from Feb 2018 to Dec 2018 were enrolled in the study. At the baseline, all patients underwent overnight PSG study, multiple sleep latency test (MSLT), psychomotor vigilance test (PVT), and Epworth sleepiness score (ESS). After CPAP therapy, all patients underwent MSLT and PVT. Paired nonparametric test or t test were used to compare the differences between daytime sleepiness and PVT performance before and after CPAP. Results: Compared with baseline data, AHI [68.8(42.2, 80.0) vs 7.4(3.1, 11.1) events/h, P<0.05] decreased, the percentages of non-rapid eye movement stage 3 sleep time [0(0, 0.5%) vs 4.4%(1.9%, 11.3%), P<0.05] and the percentages of rapid eye movement sleep time [18.6%(13.2%, 22.7%) vs 25.4%(23.85, 30.3%), P<0.05] increased after CPAP therapy. The reaction time (RT) [353.0(317.5, 429.5) vs 333.6(309.7, 381.4) ms, P<0.05], the slowest 10% RT [602.9(473.2, 841.3) vs 505.5(431.6, 618.8) ms, P<0.05] and the fastest 10% RT [260.8(236.6, 300.6) vs 251.4(233.6, 283.2) ms, P<0.05] shortened, and the lapse [6.0(2.5, 16.5) vs 3.0(1.0, 8.5) events, P<0.05] decreased. The mean sleep latency (MSL) [5.8 (3.4, 8.3) vs 7.5(4.7, 12.4) min, P<0.05] increased. The changes in PVT parameters [ΔRT (r=0.20, P>0.05), Δslowest 10% RT (r=0.15, P>0.05), Δfastest 10% RT (r=0.24, P>0.05), and Δlapse (r=0.15, P>0.05)] were not correlated with the change in MSL. The significant association between the slowest 10% RT and ESS was found in baseline data. Conclusions: The change in MSL is not associated with the change in PVT performance before and after CPAP therapy. MSLT and PVT may be different in nature.

[Association between mixed sleep apnea and treatment-emergent central sleep apnea]

Objective: To examine the association between mixed sleep apnea (MA) and treatment-emergent central sleep apnea (TE-CSA). Methods: A total of 256 patients meeting the diagnostic criteria of moderate to severe obstructive sleep apnea (OSA) based on overnight polysomnography (PSG) and receiving continuous positive airway pressure (CPAP) therapy in West China Hospital, Sichuan University during the period from August 2013 to November 2018 were enrolled in the study. Based on the mixed apnea index (MAI) and apnea-hypopnea index (AHI) in the baseline PSG study during non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep, the subjects were categorized into three groups of A (MAI=0/h, n=110), B (NREM-MAI≥5/h and REM-MAI<5/h, n=72) and C (REM-MAI≥5/h and NREM-MAI< 5/h, n=74). Sleep and breathing related parameters before and after CPAP therapy among three groups and the difference of TE-CSA incidence were analyzed. Results: The AHI [(44.2(26.8,64.5)/h,66.6(56.0,81.7)/h, 79.8(63.6, 88.3)/h], REM-AHI [50.0(34.7, 64.7)/h, 60.1(49.1, 70.0)/h, 66.3(56.1, 74.6)/h] and NREM-AHI[43.5(25.9, 65.1)/h,67.6(53.7, 82.4)/h,81.3(64.2, 91.5)/h]) were higher in group B and C compared to group A (all P<0.05),while the mean and lowest oxygen saturation [(92.6%±3.5%),(90.8%±3.6%),(87.3%±5.1%) and (70.6%±14.1%), (61.0%±16.0%), (47.9%±17.0%)] were lower in group B and group C compared to group A (all P<0.05). The incidence of TE-CSA after initial CPAP was 7.8% in all patients, and the incidence was significantly higher in group B of 14.1% compared to group C of 4.1% and group A of 2.7% (all P<0.05). Conclusions: TE-CSA is correlated with baseline MA, and baseline MA in NREM sleep can predict the incidence of TE-CSA after initial CPAP.

Candidate CSPG4 mutations and induced pluripotent stem cell modeling implicate oligodendrocyte progenitor cell dysfunction in familial schizophrenia

Schizophrenia is highly heritable, yet its underlying pathophysiology remains largely unknown. Among the most well-replicated findings in neurobiological studies of schizophrenia are deficits in myelination and white matter integrity; however, direct etiological genetic and cellular evidence has thus far been lacking. Here, we implement a family-based approach for genetic discovery in schizophrenia combined with functional analysis using induced pluripotent stem cells (iPSCs). We observed familial segregation of two rare missense mutations in Chondroitin Sulfate Proteoglycan 4 (CSPG4) (c.391G > A [p.A131T], MAF 7.79 × 10-5 and c.2702T > G [p.V901G], MAF 2.51 × 10-3). The CSPG4A131T mutation was absent from the Swedish Schizophrenia Exome Sequencing Study (2536 cases, 2543 controls), while the CSPG4V901G mutation was nominally enriched in cases (11 cases vs. 3 controls, P = 0.026, OR 3.77, 95% CI 1.05-13.52). CSPG4/NG2 is a hallmark protein of oligodendrocyte progenitor cells (OPCs). iPSC-derived OPCs from CSPG4A131T mutation carriers exhibited abnormal post-translational processing (P = 0.029), subcellular localization of mutant NG2 (P = 0.007), as well as aberrant cellular morphology (P = 3.0 × 10-8), viability (P = 8.9 × 10-7), and myelination potential (P = 0.038). Moreover, transfection of healthy non-carrier sibling OPCs confirmed a pathogenic effect on cell survival of both the CSPG4A131T (P = 0.006) and CSPG4V901G (P = 3.4 × 10-4) mutations. Finally, in vivo diffusion tensor imaging of CSPG4A131T mutation carriers demonstrated a reduction of brain white matter integrity compared to unaffected sibling and matched general population controls (P = 2.2 × 10-5). Together, our findings provide a convergence of genetic and functional evidence to implicate OPC dysfunction as a candidate pathophysiological mechanism of familial schizophrenia.

[Gender differences of REM related obstructive sleep apnea-hypopnea syndrome]

Objective: To explore the gender differences of rapid-eye-movement (REM) related obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods: Consecutive patients with primary complaint of snoring from Sleep Medicine Center of West China Hospital between January 2016 and November 2016 were included in the study. All participants underwent one night polysomnography (PSG) and Epworth sleep scale (ESS) was estimated. The patients diagnosed with OSAHS were classified as REM related OSAHS (REM-OSAHS group) and non-rapid-eye-movement (NREM) related OSAHS (NREM-OSAHS group) based on the PSG parameters. And the gender differences of demographic and polysomnograpic characteristics in both groups were compared. The associations between apnea-hypopnea index (AHI) and body mass index (BMI), neck circumference and waist circumference among patients with OSAHS were explored by multiple linear regression analysis. Results: A total of 1 258 patients were diagnosed with OSAHS. There were 997 (79.3%) male and 261 (20.7%) female among these patients, the mean age was (46.4±12.0) years old and mean BMI was (26.6±3.4) kg/m(2). There were 236 patients (18.8%) classified into REM-OSAHS group, and 1 022 patients (81.2%) classified into NREM-OSAHS group; the proportion of REM-OSAHS in female was significantly higher than that in male (34.1% vs 14.7%, P<0.001). After controlling for age, drinking, smoking, hypnotics, coffee, strong tea and sleep related parameters, in NREM-OSAHS group, AHI was positively correlated with BMI, neck circumference and waist circumference (P<0.001) both in male and female. In REM-OSAHS group, AHI was positively correlated with BMI, neck circumference and waist circumference in female (P<0.05), but only significantly correlated with BMI and waist circumference in male (P<0.05). Conclusions: REM-OSAHS is commonly seen in female OSAHS patients. Evaluation of the influences of anthropometric data on the severity of REM-OSAHS should consider the impact of gender.

[Association between subjective and objective sleepiness in obstructive sleep apnea hypopnea syndrome patients]

Objective: To examine the association between subjective sleepiness and objective sleepiness in Chinese obstructive sleep apnea hypopnea syndrome (OSAHS) patients. Methods: A total of 1 660 patients meeting the diagnostic criteria of OSAHS based on overnight polysomnography from West China Hospital, Sichuan University in the period from Jul 2010 to Jul 2014 were enrolled in the study. The Epworth Sleepiness Scale (ESS) and Multiple Sleep Latency Test (MSLT) were to evaluate subjective and objective sleepiness, respectively. The subjects were categorized into quartiles [A (0-4) (n=406), B (5-7) (n=325), C (8-12) (n=443), D(13-24) (n=486) groups] based on the ESS score distribution. Survival analysis was used to characterize the association between the ESS score and the mean sleep latency (MSL). Results: The apnea hypopnea index (AHI) in D group was higher than other three groups [(58.7±26.1) vs (36.8±24.2), (42.6±26.7), (45.7±26.6) events/h, all P<0.05]. The mean sleep latency in D group was shorter than other three groups [(8.0±4.6) vs (10.9±4.4), (10.3±4.8), (9.4±4.5) min, all P<0.05]. The Kaplan-Meier survivor functions across the ESS score quartiles were distinct and fourth quartiles were progressively associated with a greater tendency for falling asleep (χ(2)=77.76, P<0.001 by Log-rank test) in the daytime (The percentages of awaking patients in fourth quartiles were progressively lower at the same time). The adjusted hazard ratios for sleep onset during the MSLT for the group B, C and D were 1.05 (95%CI: 0.90-1.22), 1.22 (95%CI: 1.07-1.40), and 1.38 (95%CI: 1.20-1.60), respectively, comparing to group A. Conclusion: Subjective report of daytime sleepiness is consistent with the objective sleepiness in OSAHS patients.

Serum total bilirubin levels are negatively correlated with metabolic syndrome in aged Chinese women: a community-based study

We evaluated serum total bilirubin levels as a predictor for metabolic syndrome (MetS) and investigated the relationship between serum total bilirubin levels and MetS prevalence. This cross-sectional study included 1728 participants over 65 years of age from Eastern China. Anthropometric data, lifestyle information, and previous medical history were collected. We then measured serum levels of fasting blood-glucose, total cholesterol, triglycerides, and total bilirubin, as well as alanine aminotransferase activity. The prevalence of MetS and each of its individual component were calculated per quartile of total bilirubin level. Logistic regression was used to assess the correlation between serum total bilirubin levels and MetS. Total bilirubin level in the women who did not have MetS was significantly higher than in those who had MetS (P<0.001). Serum total bilirubin quartiles were linearly and negatively correlated with MetS prevalence and hypertriglyceridemia (HTG) in females (P<0.005). Logistic regression showed that serum total bilirubin was an independent predictor of MetS for females (OR: 0.910, 95%CI: 0.863-0.960; P=0.001). The present study suggests that physiological levels of serum total bilirubin might be an independent risk factor for aged Chinese women, and the prevalence of MetS and HTG are negatively correlated to serum total bilirubin levels.

Isolation and characterization of two VpYABBY genes from wild Chinese Vitis pseudoreticulata

The establishment of abaxial-adaxial polarity is an important feature of the development of lateral organs in plants. Members of the YABBY gene family may be specific to seed-plant-specific transcriptional regulators that play critical roles in promoting abaxial cell fate in the model eudicot, Arabidopsis thaliana. However, recent study has shown that the roles of YABBY genes are not conserved in the development of angiosperms. The establishment of abaxial-adaxial polarity has not been studied in perennial fruit crops. Grapes are an important fruit crop in many regions of the world. Investigating YABBY genes in grapevines should help us to discover more about the key genetic and molecular pathways in grapevine development. To understand the characterization of YABBY genes in grapevines, two YABBY genes, VpYABBY1 (GenBank accession No. KC139089) and VpYABBY2 (GenBank accession No. KC139090), were isolated from the wild Chinese species Vitis pseudoreticulata. Both of these encode YABBY proteins. Sequence characterization and phylogenetic analyses show that VpYABBY1 is group classified into the FIL subfamily while VpYABBY2 is a member of the YAB2 subfamily of Arabidopsis thaliana. Subcellular localization analysis indicates that VpYABBY1 and VpYABBY2 proteins are localized in the nucleus. Tissue specific expressional analysis reveals that VpYABBY1 is expressed strongly in young leaves of grape but only weakly in the mature leaves. Meanwhile, VpYABBY2 is expressed in grape stems, flowers, tendrils, and leaves. Transgenic Arabidopsis plants ectopically expressing VpYABBY1 caused the partial abaxialization of the adaxial epidermises of leaves, behaving similarly to those over-expressing FIL or YAB3 with abaxialized lateral organs. By contrast, ectopic expression of VpYABBY2 in Arabidopsis did not cause any alteration in the adaxial-abaxial polarity. Sequence characterization and phylogenetic analysis revealed that VpYABBY1 and VpYABBY2 are group-classified into two different subfamilies. They have diverged functionally in the control of lateral organ development. VpYABBY1 may have a function in leaf development, while VpYABBY2 may play a specific role in carpel development and grape berry morphogenesis. It is further possible that during the evolution of different species, YABBY family members have preserved different expression regulatory systems and functions.

Blocking the CC chemokine receptor 5 pathway by antisense peptide nucleic acid prolongs islet allograft survival

Chemokines are important regulators in the development, differentiation, and anatomic location of leukocytes. The CC chemokine receptor 5 (CCR5) is the receptor for the proinflammatory chemokines and plays an important role in islet allograft rejection. Peptide nucleic acid (PNA) is a nucleic acid analog in which the sugar phosphate backbone of natural nucleic acid has been replaced by a synthetic peptide backbone. Studies indicate that PNA inhibits both transcription and translation of targeted genes. Fullly major histocompatibility complex (MHC)-mismatched murine islet transplant models were used to test the in vivo effect of PNA CCR5 by targeting CCR5 in acute allograft rejection. PNA CCR5-treated recipients demonstrated significant prolongation (12.0 +/- 1.75 days) of functional allograft survival compared with saline (6.5 +/- 0.58 days)- or PNA mismatch-treated recipients (6.5 +/- 0.50 days). The PNA CCR5 blocked the expression of CCR5 in spleen CD3+ T cells. Lymphocytes from PNA CCR5-treated mice exhibited a reduced degree of proliferation comparable to that of saline- and PNA mismatch-treated mice. The present study indicated that PNA CCR5 has a substantial therapeutic effect to inhibit acute allograft rejection.

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).

Homogeneous fluorescent immunoassay with dry reagents

We described an assay for theophylline in serum in which the reagents for the substrate-labeled fluorescent immunoassay procedure are dry reagents in a paper matrix. This assay format is both rapid and convenient. In one such paper strip assay, the competing drug conjugate is present in the diluting buffer (dilution-into-conjugate strip assay); in another, all necessary assay reagents are contained on the strip (integral strip assay). The latter strip can be prepared by using appropriate solvents in a "two-dip" procedure, which prevents premature reaction of the assay constituents. The dilution-into-conjugates strip assays yield results that compare well with those by the corresponding solution assay (r = 0.975, standard error of estimate = 1.67 mg/L) and by "high-performance" liquid chromatography (r = 0.980, standard error of estimate = 1.49 mg/L). The integral strip results were compared with those by an enzyme immunoassay for theophylline (r = 0.990, standard error of estimate = 2.07 mg/L). Both strip assays require only a single dilution step before analysis.

Homogeneous fluorescent immunoassay with dry reagents

We described an assay for theophylline in serum in which the reagents for the substrate-labeled fluorescent immunoassay procedure are dry reagents in a paper matrix. This assay format is both rapid and convenient. In one such paper strip assay, the competing drug conjugate is present in the diluting buffer (dilution-into-conjugate strip assay); in another, all necessary assay reagents are contained on the strip (integral strip assay). The latter strip can be prepared by using appropriate solvents in a "two-dip" procedure, which prevents premature reaction of the assay constituents. The dilution-into-conjugates strip assays yield results that compare well with those by the corresponding solution assay (r = 0.975, standard error of estimate = 1.67 mg/L) and by "high-performance" liquid chromatography (r = 0.980, standard error of estimate = 1.49 mg/L). The integral strip results were compared with those by an enzyme immunoassay for theophylline (r = 0.990, standard error of estimate = 2.07 mg/L). Both strip assays require only a single dilution step before analysis.

Homogeneous substrate-labeled fluorescent immunoassay for theophylline in serum

A substrate-labeled fluorescent immunoassay for theophylline in serum is described. 8-(3-Aminopropyl)-theophylline is covalently attached to a fluorogenic enzyme substrate, 7-beta-galactosylcoumarin-3-carboxylic acid. Hydrolysis of this theophylline-labeled substrate by beta-galactosidase yields a fluorescent product. When antibody to theophylline interacts with this substrate, the resulting complex is inactive as an enzyme substrate. For measuring theophylline, competitive protein-binding reactions are set up, with the theophylline in the sample competing with the substrate for the antibody-binding sites. The substrate not bound to antibody is hydrolyzed by beta-galactosidase, producing fluorescence that is proportional to the theophylline concentration. Results for theophylline determined by this method in clinical samples of serum correlated well (r > 0.96) with results obtained by gas-chromatographic or enzyme immunoassay procedures. The within-run CV for three control samples ranged from 1.1 to 2.8%, the between-run CB from 2.3 to 4.5%.

Homogeneous substrate-labeled fluorescent immunoassay for theophylline in serum

A substrate-labeled fluorescent immunoassay for theophylline in serum is described. 8-(3-Aminopropyl)-theophylline is covalently attached to a fluorogenic enzyme substrate, 7-beta-galactosylcoumarin-3-carboxylic acid. Hydrolysis of this theophylline-labeled substrate by beta-galactosidase yields a fluorescent product. When antibody to theophylline interacts with this substrate, the resulting complex is inactive as an enzyme substrate. For measuring theophylline, competitive protein-binding reactions are set up, with the theophylline in the sample competing with the substrate for the antibody-binding sites. The substrate not bound to antibody is hydrolyzed by beta-galactosidase, producing fluorescence that is proportional to the theophylline concentration. Results for theophylline determined by this method in clinical samples of serum correlated well (r &gt; 0.96) with results obtained by gas-chromatographic or enzyme immunoassay procedures. The within-run CV for three control samples ranged from 1.1 to 2.8%, the between-run CB from 2.3 to 4.5%.

Effect of pressure upon the fluorescence of various flavodoxins

The effects of hydrostatic pressure in the range of 10(-3) to 11 kbar on the fluorescence of flavodoxins from Peptostreptococcus elsdenii, Desulfovibrio vulgaris, Azotobacter vinelandii, and Clostridium MP were investigated. The first three flavoproteins showed under high pressure enhancements of flavin fluorescence of over 50 times resulting from the release of flavin mononucleotide from the protein complex. The Clostridial flavodoxin showed a very much smaller fluorescence change. At pH 7.5 the high-pressure fluorescence changes of the flavodoxins of D. vulgaris and P. elsdenii were not reversed by decompression, but in A. Vinelandii the pressure changes were over 80% reversible. At pH 5 over 80% reversibility was restored to the flavodoxins of D. vulgaris and P. elsdenii, although the pressure dependence of the fluorescence changes was very similar in the reversible and irreversible cases. The midpoint pressures in the reversible reactions were 4.7 kbar (D. vulgaris), 8.7 kbar (P. elsdenii), and 10.6 kbar (A. vinelandii) indicating specific differences in the flavin binding regions. Apparent volume changes in these reactions were 65-75 mL/mol indicating participation of a large fraction of the protein in the pressure-induced changes. The irreversible changes are not related to protein aggregation and are believed to result from a pressure-dependent covalent modification, not yet characterized, of the flavin binding region of the protein.

Volume changes in the formation of internal complexes of flavinyltryptophan peptides

The effect of pressure, up to 10 kbar, on the fluorescence yield and lifetime of two flavinyltryptophan peptides was investigated. These peptides differed only in the number of methylene groups, respectively three and five, separating the chromophores. At atmospheric pressure the closed nonfluorescent form predominated in both compounds constitutin 94% of the total in the short-linked peptide and 80% in the long-linked one. The fluorescence of both peptides decreased at high pressure and the volume change upon formation of the nonfluorescent complex in the short peptide (--1.8 mL/mol) was less than half of the change in the long peptide (--4.8 mL/mol) or the value for FAD (--4.3 mL/mol). The much smaller compressibility of the short peptides is attributed to the mechanical constraint to the approach of the interacting rings, imposed by the short link. Mechanical constraints of similar nature may be expected to be operative in proteins. Their importance in pressure denaturation is discussed.

Effects of pressure upon the fluorescence of the riboflavin binding protein and its flavin mononucleotide complex

The effect of pressure in the range of 10(-3)-10 kbars upon the ultraviolet fluorescence of the riboflavin binding protein and the fluorescences of its complex with flavin mononucleotide has been studied. The fluorescence spectrum of the isolated protein showed a reversible red shift of 12nm (1000 cm-1) at high pressure, indicating the reversible exposure of the tryptophan to solvent. From the pressure dependence of the visible fluorescence of the protein-flavin complex in the region of 1-4 kbars the volume change in dissociation of the protein-ligand complex was estimated to be +3.3ml/mol. A very sharp increase in fluorescence-up to 30-fold of the low-pressure value-takes place in the region 5-8 kbars. This increase is due to release of the flavin from the complex and is assigned to pressure denaturation of the protein. The midpoint, rho 1/2, of this transition was found at 6.5 kbars and the change in volume, delta, in the reaction (native-to-denatured) was calculated to be -74ml/mol. Addition of up to 30% methanol results in a progressive decrease both in delta and rho 1/2, in agreement with the concept that hydrophobic bonding stabilizes the native structure.