Control of an outbreak of COVID-19 at a tertiary hospital in Taiwan

BACKGROUND

Coronavirus disease 2019 (COVID-19) has circulated in Taiwan since late 2019. Healthcare facilities are vulnerable to COVID-19 outbreaks due to clusters of symptomatic patients and susceptible hosts. Prompt control of outbreaks is crucial. In May 2021, an index case of COVID-19 was detected at Far Eastern Memorial Hospital (FEMH) in New Taipei City, Taiwan, 3 days after hospital admission, spreading to 26 patients and staff. Herein we evaluate control of this COVID-1 outbreak.

METHODS

To control the outbreak, the index case ward was closed, and large-scale COVID-19 testing (RT PCR) was performed for all inpatients, caregivers and healthcare workers (HCWs). All exposed persons were quarantined. Thorough investigation was conducted to analyze the transmission route.

RESULTS

The outbreak comprised 12 patients, 12 caregivers, and 3 HCWs. Seven patients expired and the remaining cases recovered. Overall, 456 patients/caregivers and 169 HCWs were quarantined. Analysis showed that longer exposure time was the main cause of HCW infection; all three infected HCWs were primary-care nurses related to the index case. To diminish hidden cases, all hospitalized patients/caregivers received PCR examinations and all results were negative. Thereafter, all patients/caregivers routinely received PCR examination on admission. Hospital-wide PCR screening for HCW detected 4 positive HCWs unrelated to this outbreak, and a second-round of screening detected 2 more cases, with no additional cases during the following 6 months.

CONCLUSION

Prompt infection control measures and large-scale PCR screening can control a COVID-19 outbreak within 2 weeks. Exposure time is the major risk factor for HCW infection.

Screening for Cryptococcal Antigenemia and Burden of Cryptococcosis at the Time of HIV Diagnosis: A Retrospective Multicenter Study

Introduction

Screening for cryptococcal antigen (CrAg) is recommended for people living with HIV (PLWH) who present with low CD4 lymphocyte counts. Real-world experience is important to identify gaps between the guidelines and clinical practice. We investigated the trends of CrAg testing and prevalence of cryptococcal antigenemia among PLWH at the time of HIV diagnosis and the related mortality in Taiwan from 2009 to 2018.

Methods

Medical records of newly diagnosed PLWH seeking care at six medical centers around Taiwan between 2009 and 2018 were reviewed. The annual trends of PLWH who had CrAg testing and cryptococcal antigenemia were examined by Cochran-Armitage test. Among PLWH with CD4 < 200 cells/µl, timing of CrAg testing was analyzed for association with 12-month all-cause mortality in Kaplan-Meier plots and in a Cox proportional hazards model after adjustments.

Results

Among 5372 included PLWH, 1150 (21.4%) presented with baseline CD4 < 100 cells/µl, and this proportion had decreased during the study period [from 108 (29.3%) in 2009 to 93 (22.3%) in 2018 (P = 0.039)]. The overall prevalence of cryptococcal antigenemia was 7.8% among PLWH with CD4 < 100 cells/µl, which remained stable during the 10-year study period (P = 0.356) and was 2.6% among PLWH with CD4 100–199 cells/µl. The uptake of CrAg testing had increased from 65.7% in 2009 to 78.0% in 2018 (P = 0.002) among PLWH with CD4 < 100 cells/µl. Late CrAg testing, defined by 14 days or later after HIV diagnosis, was associated with increased risk of 12-month mortality compared to early CrAg testing (adjusted hazard ratio 2.028, 95% CI 1.109–3.708).

Conclusions

Burden of cryptococcosis remained high among PLWH with low CD4 lymphocyte counts in Taiwan. Uptake of CrAg screening among late HIV presenters was still suboptimal and delayed. Late CrAg testing was associated with a higher mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00451-5.

Klebsiella pneumoniae bacteremia revisited: Comparison between 2007 and 2017 prospective cohorts at a medical center in Taiwan

BACKGROUND

Community onset K. pneumoniae bacteremia (KPB) is a major problem in Taiwan for decades. We aimed to revisit the role of virulent genotype K1/K2 and possible predisposing factors, compared to our published 2007 cohort.

METHODS

All adult patients with monomicrobial KPB during 2017 at a medical center in Taiwan were prospectively enrolled. We genotyped the major K types of K. pneumoniae strains, and analyzed the role of prior use of antibiotic or proton pump inhibitor (PPI).

RESULTS

A total of 213 cases were enrolled. Compared to our previous 2007 study (n = 231), there was a higher percentage of patients with community onset bacteremia (75% vs. 60%, p = 0.003). The overall mortality rate was lower in 2017 (23% vs. 32%, p = 0.02), while the rates of antimicrobial resistance (all classes) were higher in 2017. There were 40 cases of liver abscesses in 2017 (19%), with an overall mortality rate of 7.5%. The prevalence of K1 was similar (16% in 2017 vs. 19% in 2007), but the prevalence of K2 decreased significantly (7% in 2017 vs. 17% in 2007, p = 0.001). After excluding 39 cases without data of recent medication use, 48 of 174 (28%) of patients had received a PPI within 90 days. Patients with recent PPI use had more complicated underlying illnesses, higher antimicrobial resistance, and higher in-hospital mortality, but was negatively associated with liver abscess (4% vs. 24%, p = 0.002). Of patients with community-acquired bacteremia, 51% used antibiotics within 90 days. After excluding 37 patients received antibiotics within 14 days before the detection of bacteremia, patient with antibiotic use within 15-90 days had higher Pittsburgh bacteremia scores (4.5 vs. 2.7, p = 0.04), creatinine levels, and frequency of recent surgery, but was not associated with liver abscess (21% vs. 31%, p = 0.33).

DISCUSSION

In summary, after a decade, community onset KPB is still prevalent (1.3 case per 1000 emergency department visit). K1 remains to be the dominant genotype. The association of prior ampicillin/amoxicillin or PPIs use for liver abscess is not confirmed.

Ongoing transmission of Entamoeba histolytica among newly diagnosed people living with HIV in Taiwan, 2009-2018

Recent outbreaks of enterically transmitted infections, including acute hepatitis A and shigellosis, have raised the concerns of increasing Entamoeba histolytica infection (EHI) among people living with HIV (PLWH) in Taiwan. This study investigated the prevalence of EHI, its temporal trends, and associated factors among newly diagnosed PLWH in Taiwan. Medical records of newly diagnosed PLWH at six medical centers in Taiwan between 2009 and 2018 were reviewed. The annual prevalence of invasive amoebiasis and seroprevalence of E. histolytica were determined and examined by the Cochran-Armitage test. The clinical characteristics associated with invasive amoebiasis and seropositivity for E. histolytica were analyzed in multivariable regression models. Among 5362 patients seeking HIV care at six medical centers in Taiwan during the 10-year study period, 119 (2.2%) had invasive amoebiasis at the time or within six months of their HIV diagnosis. Among 3499 who had indirect hemagglutination antibody (IHA) determined, 284 (8.1%) had positive IHA (≥1:32) and 205 (5.9%) had high-titre IHA (≥1:128). The prevalence of invasive amoebiasis increased from 1.3% in 2012 to 3.3% in 2018 (p = 0.024). Invasive amoebiasis was independently associated with a greater age, men who have sex with men, rapid plasma reagin titre ≥1:4, and concurrent shigellosis and giardiasis. Increasing prevalence of invasive amoebiasis among newly diagnosed PLWH in Taiwan calls for strategies to prevent ongoing transmission in this population. Routine screening of EHI for early diagnosis and treatment is recommended, especially among men who have sex with men and those who present with other sexually or enterically transmitted infections.

Outbreaks of enterically transmitted infection, including acute hepatitis A and shigellosis, among men who have sex with men and people living with HIV have been reported in Taiwan and in many developed countries in recent years. This study reveals that the prevalence of invasive amoebiasis among newly diagnosed people living with HIV increased in Taiwan since 2012, accompanied by increasing seroprevalence of syphilis and hepatitis A virus infection. This study also shows that concurrent infections with shigellosis and giardiasis and history of syphilis were independently associated with invasive amoebiasis, which indicates that transmission of Entamoeba histolytica might have occurred through sexual behaviours that increased faecal-oral contact in this population. In the era of improved access to HIV prevention and treatment, emerging and re-emerging enterically transmitted infections, including amoebiasis, pose an ongoing health threat to at-risk individuals and the public as a whole.

Increased risks of tic disorders in children with epilepsy: A nation-wide population-based case-control study in Taiwan

Both epilepsy and tic disorders may share common mechanisms with the involvement of abnormal cortical-basal ganglion circuit connection and dopaminergic dysfunction. However, the association between epilepsy and tic disorders has never been studied. This study investigated the risks of developing tic disorders among children with epilepsy using databases of a universal health insurance system in Taiwan. The data analyzed in this study were retrieved from the National Health Insurance Research Database in Taiwan. The study cohort included children with epilepsy between 2001 and 2007 (n=2629) and a three-fold age- and gender-matched controls (n=7887). All subjects were followed up for 3 years from the date of cohort entry to identify their admissions due to tic disorders (ICD-9-CM codes 307.2, 307.20-307.23). Cox hazard regression analysis was performed to estimate the effect of epilepsy on the occurrence of tics. The epilepsy cohort had a higher prevalence of tics (1.7% vs. 0.2%), and a 8.70-fold increased risk of developing a tic disorder compared with the controls (adjusted hazard ratio (AHR) 8.70, 95% confidence interval (CI) 4.26-16.37, p<0.001). Male patients were observed to have a higher risk of developing a tic disorder (AHR 1.90, 95% CI=1.04-3.46, p<0.001) compared to female individuals. Patients with multiple antiepileptic drugs treatment also exhibited higher crude OR for developing tic disorders. This nationwide population-based cohort study, for the first time, demonstrated that there is a significantly increased risk for tic disorders among children with epilepsy. We also found males, attention deficit disorder and the use of multiple AEDs to be independent risk factors of tic disorders. Closely evaluating possible tic disorders would be crucial for improving the outcome and life quality in children with epilepsy.

Increased risk of epilepsy in children with Tourette syndrome: A population-based case-control study

The association between epilepsy and Tourette syndrome has rarely been investigated. In this retrospective cohort study, we analyzed a dataset of 1,000,000 randomly sampled individuals from the Taiwan National Health Insurance Research Database to determine the risk of epilepsy in children with Tourette syndrome. The study cohort consisted of 1062 patients with Tourette syndrome aged ≤ 18 years, and the control group consisted of three times the number of age- and sex-matched patients without Tourette syndrome, who were insurants, from the same database during the same period. The Tourette syndrome group had an 18.38-fold increased risk of epilepsy than the control group [hazard ratio=18.38, 95% confidence interval (CI)=8.26-40.92; P<0.001]. Even after adjusting for the comorbidities, the risk of epilepsy in the Tourette syndrome group with comorbidities remained high (hazard ratio=16.27, 95% CI=6.26-18.46; P<0.001), indicating that the increased risk was not associated with comorbidities. This population-based retrospective cohort study provides the first and strong evidence that Tourette syndrome is associated with a higher risk of epilepsy. A close follow-up of children with Tourette syndrome for the development of epilepsy is warranted.

Is schizophrenia associated with an increased risk of chronic kidney disease? A nationwide matched-cohort study

OBJECTIVE

The impact of schizophrenia on vital diseases, such as chronic kidney disease (CKD), has not as yet been verified. This study aims to establish whether there is an association between schizophrenia and CKD.

DESIGN

A nationwide matched cohort study.

SETTING

Taiwan's National Health Insurance Research Database.

PARTICIPANTS

A total of 2338 patients with schizophrenia, and 7014 controls without schizophrenia (1:3), matched cohort for sex, age group, geography, urbanisation and monthly income, between 1 January 2003 and 31 December 2007, based on the International Classifications of Disease Ninth Edition (ICD-9), Clinical Modification codes.

PRIMARY AND SECONDARY OUTCOME MEASURES

After making adjustments for confounding risk factors, a Cox proportional hazards model was used to compare the risk of developing CKD during a 3-year follow-up period from the index date.

RESULTS

Of the 2338-subject case cohort, 163 (6.97%) developed a CKD, as did 365 (5.20%) of the 7014 control participants. Cox proportional hazards regression analysis revealed that patients with schizophrenia were more likely to develop CKD (HR=1.36, 95% CI 1.13 to 1.63; p<0.001). After adjusting for gender, age group, hypertension, diabetes mellitus, hyperlipidaemia, heart disease and non-steroid anti-inflammatory drugs (NSAIDs) usage, the HR for patients with schizophrenia was 1.25 (95% CI 1.04 to 1.50; p<0.05). Neither typical nor atypical antipsychotics was associated an increased risk of CKD in patients with schizophrenia.

CONCLUSIONS

The findings from this population-based retrospective cohort study suggest that schizophrenia is associated with a 25% increase in the risk of developing CKD within only a 3-year follow-up period.

The effect of etanercept on anti-cyclic citrullinated peptide antibodies and rheumatoid factor in patients with rheumatoid arthritis

OBJECTIVE

To evaluate the changes in anti-cyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factor (RF) following etanercept treatment in patients with rheumatoid arthritis.

METHODS

The study included 90 patients with rheumatoid arthritis who failed treatment with disease modifying antirheumatic drugs (DMARDs). All patients were allowed to continue treatment with DMARDs; 52 of them received etanercept as a twice weekly 25 mg subcutaneous injection for three months, and the others did not. Serum samples were collected at baseline and one month intervals during the treatment course. The serum levels of anti-CCP and RF were tested by enzyme linked immunosorbent assay and nephelometry, respectively.

RESULTS

At baseline, 45 of the 52 etanercept treated patients (86.5%) and 32 of the 38 controls (84.2%) were positive for anti-CCP. Tests for RF were positive in 78.9% and 84.2% of patients with or without etanercept treatment, respectively. The serum levels of anti-CCP and RF decreased significantly after a three month etanercept treatment (p = 0.007 and p = 0.006, respectively). The average decrease from baseline calculated for each individual patient in the etanercept treated group was 31.3% for anti-CCP and 36% for RF. The variation in anti-CCP was positively correlated with the variation in disease activity, swollen and tender joint counts, RF, and C reactive protein.

CONCLUSIONS

Etanercept combined with DMARDs leads to a much greater decrease than DMARDs alone in the serum levels of anti-CCP and RF in rheumatoid arthritis, compatible with a reduction in clinical disease activity.

The pH dependence of CD2 domain 1 self-association and 15N chemical exchange broadening is correlated with the anomalous pKa of Glu41

We have previously shown using (15)N nuclear relaxation measurements that the concentration-dependent rotational correlation time and chemical exchange broadening for selected resonances of rat CD2 domain 1 (CD2d1) are consistent with a model of low-affinity self-association of the protein molecules. The exchange broadening data, which at high protein concentrations highlight selected nuclei in the major C'-C-F-G beta-sheet face of the immunoglobulin fold, implicate a surface reminiscent of the major lattice contact within crystals of the intact CD2 ectodomain. In a separate study, we have also demonstrated that the beta-strand C' surface-exposed residue Glu41 possesses an anomalously elevated acidity constant (pK(a) = 6.7 at a protein concentration of 1.2 mM). Mutagenesis studies showed that the close contact of residue Glu41 with Glu29 (beta-strand C) is the primary cause of the high pK(a). However, the measured pK(a) of Glu41 also shows a weak dependence on protein concentration, implicating Glu41 in the mechanism of CD2d1 self-association. In the study presented here, we demonstrate a correlation of the pH dependence of the chemical shift and (15)N nuclear relaxation parameters measured for wild-type and mutant forms of CD2d1 with pH and the protonation state of Glu41. Self-association of CD2d1 molecules is promoted whenever the side chain charge of residue 41 is neutralized. These observations are consistent with a model for CD2d1 self-association that corresponds to the crystal structure lattice contact where the interatomic distances are consistent with Glu41 being in the protonated state. This study reinforces the conclusion that residue-specific chemical exchange broadening of protein resonances can arise from weak self-association phenomena. In addition, the electrostatic profile of rat CD2 interfacial residues parallels that of the homologous human CD2 in a manner that suggests a rationalization of similar exchange broadening observations.

The solution structure of PapGII from uropathogenic Escherichia coli and its recognition of glycolipid receptors

Uropathogenic Escherichia coli (UPEC) is the primary cause of symptomatic urinary tract infection. The P-pili, a bacterial surface organelle, mediates the bacterial host--cell adhesion. The PapG adhesin has generated much interest in recent years, not only because of its clinical value, i.e. in the prevention of microbial adherence, but also because of its ability to promote virulence. Using multidimensional nuclear magnetic resonance (NMR) and deuteration we have determined the solution structure of the adhesin domain from PapGII (PapGII-198). The novel structure of PapGII-198 is composed of a large elongated jellyroll motif. Despite an automated search of the structural database failing to reveal any similar proteins, PapGII adhesin shares some structural similarities with FimH. Furthermore, interpretation of NMR-titration data has enabled us to identify the putative binding site for the globoseries of oligosaccharides. This work provides insight into UPEC pathogenesis as well as aiding the development of preventative therapies and the guidance of future mutagenesis programmes.

Determination of pK(a) values of carboxyl groups in the N-terminal domain of rat CD2: anomalous pK(a) of a glutamate on the ligand-binding surface

The ligand-binding surface of the T-lymphocyte glycoprotein CD2 has an unusually high proportion of charged residues, and ionic interactions are thought to play a significant role in defining the ligand specificity and binding affinity of CD2 with the structurally homologous ligands CD48 (in rodents) and CD58 (in humans). The determination of the electrostatic properties of these proteins can therefore contribute to our understanding of structure-activity relationships for these adhesion complexes that underpin T-cell adhesion to antigen-presenting cells. In this study, we investigated the pH titration behavior of the carboxyl groups of the N-terminal domain of rat CD2 (CD2d1) using the chemical shifts of backbone amide nitrogen-15 ((15)N) and proton NMR resonances, and carboxyl carbon-13 ((13)C) signals. The analysis revealed the presence of a glutamate (Glu41) on the binding surface of rat CD2 with an unusually elevated acidity constant (pK(a) = 6.73) for CD2d1 samples at 1.2 mM concentration. pH titration of CD2d1 at low protein concentration (0.1 mM) resulted in a slight decrease of the measured pK(a) of Glu41 to 6.36. The ionization of Glu41 exhibited reciprocal interactions with a second glutamate (Glu29) in a neighboring location, with both residues demonstrating characteristic biphasic titration behavior of the carboxyl (13)C resonances. Measurements at pH 5.5 of the two-bond deuterium isotope shift for the (13)C carboxyl resonances for Glu41 and Glu29 [(2)DeltaC(delta)(O(epsilon)D) = 0.2 and 0.1 ppm, respectively] were consistent with the assignment of the anomalous pK(a) to Glu41, under the strong influence of Glu29. The characterization of single site mutations of CD2d1 residues Glu41 and Glu29 to glutamine confirmed the anomalous pK(a) for Glu41, and indicated that electrostatic interaction with the Glu29 side chain is a significant contributing influence for this behavior in the wild-type protein. The implications of these observations are discussed with respect to recent structural and functional analyses of the interaction of rat CD2 with CD48. In particular, CD2 Glu41 must be a candidate residue to explain the previously reported strong pH dependence of binding of these two proteins in vitro.

NMR exchange broadening arising from specific low affinity protein self-association: analysis of nitrogen-15 nuclear relaxation for rat CD2 domain 1

Nuclear spin relaxation monitored by heteronuclear NMR provides a useful method to probe the overall and internal molecular motion for biological macromolecules over a variety of time scales. Nitrogen-15 NMR relaxation parameters have been recorded for the N-terminal domain of the rat T-cell antigen CD2 (CD2d1) in a dilution series from 1.20 mM to 40 microM (pH 6.0, 25 degrees C). The data have been analysed within the framework of the model-free formalism of Lipari and Szabo to understand the molecular origin of severely enhanced transverse relaxation rates found for certain residues. These data revealed a strong dependence of the derived molecular correlation time tau c upon the CD2d1 protein concentration. Moreover, a number of amide NH resonances exhibited exchange broadening and chemical shifts both strongly dependent on protein concentration. These amide groups cluster on the major beta-sheet surface of CD2d1 that coincides with a major lattice contact in the X-ray structure of the intact ectodomain of rat CD2. The complete set of relaxation data fit well to an equilibrium monomer-dimer exchange model, yielding estimates of exchange rate constants (kON = 5000 M-1 s-1; kOFF = 7 s-1) and a dissociation constant (KD approximately 3-6 mM) that is consistent with the difficulty in detecting the weak interactions for this molecule by alternative biophysical methods. The self-association of CD2d1 is essentially invariant to changes in buffer composition and ionic strength and the associated relaxation phenomena cannot be explained as a result of neglecting anisotropic rotational diffusion in the analysis. These observations highlight the necessity to consider low affinity protein self-association interactions as a source of residue specific exchange phenomena in NMR spectra of macromolecular biomolecules, before the assignment of more elaborate intramolecular conformational mechanisms.

Orthodontic correction of a mandibular first molar deeply impacted by an odontoma: a case report

Orthodontic correction was used to a 12-year-old boy with a mandibular first molar deeply impacted by an odontoma. Following surgical removal of the odontoma, the molar was exposed and brought to a proper position by orthodontic traction. The treatment time was 29 months. After a 20-month follow-up, the molar was still in a satisfactory position.

Recognition of antigenic epitopes in lipopolysaccharide and protein from Actinobacillus actinomycetemcomitans by serum antibodies in untreated rapidly progressive periodontitis patients

Actinobacillus actinomycetemcomitans has been associated with early-onset periodontitis, including the localized juvenile and rapidly progressive forms. The immunodominant antigens of A. actinomycetemcomitans recognized by rapidly progressive periodontitis patients remain unidentified. Sera from 22 patients with rapidly progressive periodontitis and 20 periodontally normal subjects were tested by enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G antibodies to whole-cell sonicate, protein, purified lipopolysaccharide and lipopolysaccharide fractions of A. actinomycetemcomitans. The median titers of rapidly progressive periodontitis patients and control subjects to whole-cell sonicate were 25.0 and 14.5 ELISA units, respectively (not significantly different). Binding of antibody from patient sera occurred to both the lipopolysaccharide and the protein fractions, with greater binding to lipopolysaccharide than to protein. We show for the first time that patient sera contain antibodies that bind specifically to antigenic epitopes in lipid A and in the core carbohydrate of lipopolysaccharide that were previously considered to be inaccessible and unavailable, as well as to epitopes in the O side chains. Sera manifesting antibody titers 2-fold or greater than the median titer for control sera were judged to be seropositive. More patients were seropositive for lipid A than for any of the other antigen preparations studied, and the median titer for patient sera to lipid A but to none of the other purified lipopolysaccharide fractions was significantly elevated relative to control values. Of 22 patients, 10 were seropositive to whole-cell sonicate, 7 to protein, 8 to lipopolysaccharide, 7 to the high-molecular-weight lipopolysaccharide-polysaccharide fraction rich in O side chains, and 16 to lipid A. The core carbohydrate did not adhere to the test plate surface, and this precluded ELISA measurements. However, when the core carbohydrate was used in the ELISA inhibition assay, it reduced antibody binding to lipopolysaccharide-coated plates by up to 45%, thereby demonstrating antibody binding to core carbohydrate. The core carbohydrate fraction from the Re mutant of Salmonella minnesota known to contain no O-side chains also inhibited binding of specific antibody to plates coated with A actinomycetemcomitans lipopolysaccharide. Overall, there was extreme variation in responses among patients to the various antigen preparations, with no single pattern dominating. Lipopolysaccharide and its components appear to be the immunodominant epitopes, since most rapidly progressive periodontitis patients are seropositive for lipopolysaccharide and/or its components and they have titers relative to those for proteins.

Verruciform xanthoma. Case report and literature review

Verruciform xanthoma is a relatively uncommon lesion. Half of the reported cases occurred in the gingiva or alveolar ridge. In most cases, the clinical impressions are papilloma or verrucous carcinoma, which demonstrates the importance of the clinical and pathological recognition of this lesion. The cause of pathogenesis is still unknown since the first report in 1971. There are some cases reported in conjunction with leukoplakia, carcinoma in situ, pemphigus, and discoid lupus erythematosus (DLE), which merits close evaluation of this disease. This article reports two cases of verruciform xanthoma and reviews the evidence of its pathogenesis from the available literature.

Putative benzodiazepine partial agonists demonstrate receptor heterogeneity

This study explored whether the behavioral heterogeneity of benzodiazepine receptor (BDZR) ligands is a consequence of multiple receptor subtypes or partial agonism. Putative partial agonists Ro16-6028, Ro23-1590, Ro23-0364, and abecarnil were compared with U78875, a mixed agonist-antagonist, and CGS8216, an inverse agonist, in five BDZR-mediated functions: hyperphagia, anxiolysis, sedation, hypothermia, and anticonvulsant activity. Only abecarnil was an agonist in all end points. Each of the other drugs exhibited qualitatively different responses at these end points. Specifically, Ro23-0364 produced no effect on body temperature, but was an agonist at other tests. Ro23-1590 had no effect on anxiolysis and hypothermia, but was an agonist at other tests. In contrast to other putative partial agonists, Ro16-6028 was found to be an antagonist in sedation and U78875 was an antagonist in hypothermia, but both were agonists at other end points. These qualitative differences in activity in the five behavioral end points studied cannot be explained by partial agonism at a single receptor and indicate that these ligands differentially activate multiple BDZR subtypes.

Immunodominant antigens of Porphyromonas gingivalis in patients with rapidly progressive periodontitis

W studied 4 isolates of Porphyromonas gingivalis, ATCC 33277, 381, A7A1-28, and W50, to identify major cell surface antigens and select the best strain from which to obtain antigen for a test vaccine. Immunoglobulin G (IgG) titers measured by enzyme-linked immunosorbent assay using whole-cell sonicates as antigen were significantly elevated for the sera of 64 rapidly progressive periodontitis patients relative to sera of 30 normal control subjects for each of the 4 strains studied. Western blots were prepared for all 4 strains and developed using sera from 22 patients and 20 control subjects to identify and determine the frequency of antibody-binding components. The intensity of binding by patient sera was greatest for the 75-kDa and 55-kDa components. The 43-kDa component was also widely recognized. Strains ATCC 33277 and 381 appeared to be antigenically similar. Because of the higher serum antibody titers, the larger proportion of seropositive patients and higher frequency of binding to specific protein components in Western blots, our efforts were focussed on strain ATCC 33277. Whole-cell sonicates, proteinase K-digested sonicate, lipopolysaccharide, capsular polysaccharide, and whole-cell protein fractions were prepared and evaluated for antigenic activity. By dot immunoblot, most of the antibody binding activity was found in the whole-cell protein fraction, with much lesser amounts in lipopolysaccharide and none in capsular polysaccharide. The antibody-binding activity was accessible on the cell surface, since 98.9% of P. gingivalis-specific antibody, including antibody binding to the 43-kDa, 55-kDa components on Western blot, was removed by whole-cell adsorption. Furthermore, the 43-kDa and 55-kDa but not the 75-kDa component on intact cells were accessible for labeling with 125I, confirming their cell surface location and accessibility.

Titer and subclass distribution of serum IgG antibody reactive with Actinobacillus actinomycetemcomitans in localized juvenile periodontitis

Most patients with localized juvenile periodontitis (LJP) manifest serum IgG antibodies specifically reactive with antigens of Actinobacillus actinomycetemcomitans serotype b (Aa-b). Whether these antibodies are protective, destructive, or irrelevant to the progress of the disease remains unclear. We report results of studies aimed at assessing the subclass IgG responses in 35 LJP patients and 35 periodontally normal control subjects using well-characterized monoclonal antibody subclass reagents in an enzyme-linked immunosorbent assay. Our data show that the mean value for total IgG reactive with antigens of Aa-b was more than sevenfold higher for patients than for normal control sera (2349.6 micrograms/ml for patients vs 332.2 micrograms/ml for controls). Individual patients and control subjects were classified as high- or low-titer, using twice the median value for total anti-Aa-b IgG in control sera as the cutoff. Of 35 patients, 26 (74%) were high-titer, and 9 (26%) were low-titer. This compares to 5 normal control subjects (14%) high-titer and 30 (86%) low-titer. IgG2 accounted for the major quantitative response in both patients and control subjects. Indeed, the mean IgG2 values for both concentration and percentage of total specific IgG were greater than the combined values for specific anti-Aa-b IgG1, IgG3, and IgG4. Of the 26 high-titer sera, IgG2 predominated in 24, with IgG1 and IgG3 predominating in 1 each; IgG2 predominated in only 2 of the low-titer sera.

Humoral immune responses to Porphyromonas gingivalis before and following therapy in rapidly progressive periodontitis patients

We have performed studies aimed at elucidating the nature of the humoral immune response in rapidly progressive periodontitis (RPP). We analyzed the sera of 36 periodontally normal subjects and 36 RPP patients for titers and avidities of IgG antibodies reactive with the antigens of Porphyromonas gingivalis using ELISA, prior to and following treatment. We used whole-cell sonicate, purified lipopolysaccharide (LPS), and total extractable protein as plate antigens. Twelve of the patients had antibody titers at least 2-fold greater than the median of the controls and were designated as seropositive. The remaining 24 patients had titers that did not exceed twice the median titer of the controls and were designated as seronegative. For both patient groups, antibody titers were highest when whole-cell antigen was used, intermediate for LPS, and lowest for the protein fraction. Following treatment, median titer for seropositive patients decreased from pretreatment values of 241.7 to 76.5, while median titer for seronegative patients increased from 39.5 to 80.1. Avidities of pretreatment sera from both patient groups for all 3 antigen preparations were lower than the median avidities of the control sera. Avidity significantly increased following treatment to levels greater than those for control sera in both patient groups. Thus, some young adults with severe periodontitis mount a humoral immune response and produce high levels of serum IgG antibodies reactive with antigens of P. gingivalis, while others do not. The antibodies produced are of relatively low avidity, and may therefore be relatively ineffective biologically. Therapy, which greatly reduces antigen load, appears to stimulate production of higher avidity IgG antibodies in both patient groups; in the seropositive group, low avidity antibodies appear to be replaced by antibodies of higher avidity. Both the purified LPS and protein fractions contain reactive antigen(s), although LPS binds more antibody. Our data are consistent with the idea that many RPP patients do not produce protective levels of biologically functional antibody during the course of their natural infection, but they may be stimulated to do so by treatment.