Commercial Enzyme-linked Immunosorbent Assay Research Articles

Examination of the APELIN signaling pathway in acetaminophen-induced hepatotoxicity in rats

Abstract Objectives The present study identifies the level changes of markers (Apelin, Elabela, Meteorin, ALT, AST, GGT) in the liver after acute intake of high-dose paracetamol and their role in determining liver damage. Methods The rats were categorized into two groups (Control and Toxication), each consisting of seven rats. Apelin, Elabela, Meteorin, ALT, AST and GGT levels were determined in liver tissue. The levels of Apelin, Elabela, and Meteorin in liver tissue homogenate were assessed following the kit procedure, utilizing commercial enzyme-linked immunosorbent assay. ALT, AST and GGT analyzes were performed from liver tissue homogenate with Erba colorimetric kit according to the kit procedure. It was also evaluated histopathologically from liver tissue. Results Looking at the findings, a significant decrease was determined in the Elabela and Meteorin data in the Apap group compared to the control group. In the Apelin data, a statistical increase was observed in the Apap group compared to the control group. A significant increase in ALT analysis was detected in the APAP group compared to the control group. Considering GGT and AST data, a statistical increase was detected in the APAP group compared to the control group.While Bax, Bcl-2 and iNOS immunoreactivity was not observed in the control group, a yellowish-brown positive reaction was detected in the cytoplasm of degenerated and necrotic hepatocytes, especially around the vena centralis, in the paracetamol group. Conclusions As a result, it is thought that Apelin, Elabela and Meteorin markers may be decisive markers in determining toxicity in liver damage.

Early and sensitive diagnosis of celiac autoimmune disease by using carboxylic acid functionalized magnetic nanoparticles-assisted biosensing platform

A novel impedimetric magneto-immunosensor based on iron oxide (Fe3O4) nanoparticles coated with 3-phosphonopropionic acid (3-PPA) (functionalized magnetic beads, or FMBs) was created for the highly sensitive and selective detection of anti-tissue transglutaminase antibody (anti-tTG) in human serum. This label-less immunosensor was introduced by magnetically attaching FMBs onto the working electrode surface with a neodium magnet. The FMBs were utilized as a sensing interface and had carboxylic acid groups for tTG molecules, which could selectively link the target anti-tTG antibody. The FMBs modification steps were carried out in microcentrifuge tubes and concentrated with magnetic force before electrochemical analyses. The specific immuno-interactions on the FMBs surface were characterized by using the electrochemical and microscopic techniques, and in the presence of anti-tTG antibodies, they were captured by tTG-immobilized magnetic beads, and significant increases were observed in impedimetric response. The magneto biosensor response was linearly related to the anti-tTG antibody level in a broad linear range of 0.125–15.62 U/mL and a low detection limit (LOD) of 0.04 U/mL. Additionally, this magneto sensor was stable, repeatable, reproducible, selective, and sensitive for determination of the anti-tTG. The commercial enzyme-linked immunosorbent assay (ELISA) method was employed to compare the responses of the suggested immunosensor in actual samples. The magneto biosensor results were in good agreement with the ELISA reference technique results. Consequently, the biosensor performance in the analysis of serum samples was acceptable.Graphical

Detection of SARS-CoV-2- specific antibodies in domestic cats using different ELISA tests.

Detection of SARS-CoV-2- specific antibodies in domestic cats using different ELISA tests.

Highly efficient nickel-based metal atom cluster/metal oxide microsensors for the rapid and accurate screening of Helicobacter pylori infection.

Highly efficient nickel-based metal atom cluster/metal oxide microsensors for the rapid and accurate screening of Helicobacter pylori infection.

Prognostic Implications of Serum Carbonic Anhydrase IX in Clear Cell Renal Cell Carcinoma

Purpose: The present study aimed at determining the expression of carbonic anhydrase IX (CAIX) in tissue and serum of patients with clear cell renal cell carcinoma (ccRCC) and its relationship with clinical-pathological parameters; assessing CAIX as a marker of progression and survival; and studying the relationship of CAIX concentration in serum before and after surgical intervention.Materials and Methods: Immunohistochemistry was used to assess the expression of CAIX in tumor and adjacent healthy renal tissues. The concentration of CAIX in serum was determined using commercial enzyme-linked immunosorbent assay before and 24 hours after radical nephrectomy in 60 patients diagnosed with ccRCC. SPSS ver. 28.0.1.0 was used for descriptive and inferential statistical analysis and graphics. A significance level of 0.05 was considered for all statistical tests performed.Results: CAIX expression was positive in 59 of the 60 samples of tumor renal tissue, and negative in the 60 samples of healthy renal tissues. Median serum CAIX concentration was higher before nephrectomy (178.25 pg/mL) than after it (59.30 pg/mL), with a high correlation between pre-and postsurgical measurements (r=0.891). Significant differences were found in CAIX concentration according to the following variables: TNM, tumor stage, Fuhrman nuclear grade, progression, and death. Serum CAIX concentration before nephrectomy correlated with disease progression and overall survival, with a hazard ratio of 4.849 for CAIX values greater than 169.95 pg/mL.Conclusion: CAIX expression in tumor renal tissue was specific, but not clinically useful as a prognostic marker. Measurements of CAIX in serum obtained pre- and postsurgical interventions showed good prognostic potential, correlating with clinical-pathological parameters and estimating the risk of progression. Presurgical intervention serum CAIX concentrations higher than 169.95 pg/mL indicated an almost 5-fold increased risk of death.

Development and application of a blocking ELISA method based on Cap protein for detecting antibodies against porcine circovirus 2

ABSTRACT Porcine circovirus type 2 (PCV2) serves as the key pathogen linked to porcine circovirus-associated disease, representing a considerable risk to the worldwide swine industry. A blocking enzyme-linked immunosorbent assay (ELISA) was established to identify antibodies specifically targeting PCV2, employing recombinant Cap protein as the antigen and a monoclonal antibody against PCV2 Cap protein as the detector antibody. Utilizing receiver operating characteristic curve analysis, a cutoff value of 33.8% was determined to distinguish between positive and negative serum samples. The sensitivity and specificity of this blocking ELISA method were reported at 94.7% and 96.1%, respectively. Notably, this approach exclusively identified antibodies for PCV2, showing no cross-reactivity with antibodies related to African swine fever virus (ASFV), Porcine epidemic diarrhea virus (PEDV), Porcine pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus. Both intra-assay and inter-assay coefficients of variation were less than 10%. In a comparison involving 402 porcine serum samples, the agreement rate with a commercial indirect ELISA kit reached 98.76%, with a kappa value of 0.888, reflecting high concordance between the two testing methods. This study showcases the blocking ELISA method as an efficient and standardized approach for serological monitoring of PCV2 in swine populations and for assessing seroconversion in vaccinated pigs. IMPORTANCE Porcine circovirus type 2 (PCV2) has become recognized as a pathogen of significant economic concern within the swine industry. PCV2 mainly affects the immune systems of pigs, leading to a reduction in lymphocytes and resulting in immune suppression in the affected animals. Co-infection with other porcine pathogens can enhance PCV2 infection and exacerbate porcine circovirus disease. Currently, the kits available for detecting PCV2 antibodies primarily employ indirect enzyme-linked immunosorbent assay (ELISA); however, this method is prone to false positives. In contrast, the blocking ELISA method offers enhanced specificity and provides a more straightforward interpretation of results. Previous studies utilizing blocking ELISA for PCV2 antibody detection have depended on plates coated with purified PCV2 virus, a process that is both technically challenging and time-consuming. Consequently, there is a pressing need to develop a new blocking ELISA method that is more efficient to detect antibodies against PCV2.

A Novel Peptide-Based Enzyme-Linked Immunosorbent Assay (ELISA) for Detection of Neutralizing Antibodies Against NADC30-like PRRSV GP5 Protein.

Porcine reproductive and respiratory syndrome (PRRS) is a pig respiratory disease threating the global swine industry. To combat PRRS, it is necessary of the effective diagnostic detection of antibody, including developing a neutralizing antibody against porcine reproductive and respiratory syndrome virus (PRRSV), especially the currently prevalent NADC30-like PRRSV in China. In this study, we prepared three monoclonal antibodies (mAbs) against NADC30-like PRRSV glycoprotein 5 (GP5) protein, and identified two corresponding precise epitopes (155WR156 and 196QWGRP200). In the neutralization test, 196QWGRP200 recognizing GP5 mAbs (11E6 and 12D1) exhibited obvious neutralizing activity, whereas the 155WR156 recognizing mAb (3A8) showed low neutralizing activity. Based on the two antigenic peptides, a peptide-based Enzyme-Linked Immunosorbent Assay (ELISA) was developed to detect antibodies against PRRSV, presenting high specificity, sensitivity, and repeatability. The concordance rate of the peptide-based ELISA and commercial IDEXX PRRSV X3 Ab ELISA in detection of 81 clinical samples was 82.7%. In conclusion, the GP5 peptide-based ELISA can be used for the detection of neutralizing antibodies against NADC30-like PRRSV, providing a rapid and reliable method for monitoring PRRSV infection.

Cervids and raccoon dogs as wildlife sentinels for the geographical distribution of tick-borne encephalitis virus and Francisella tularensis in Denmark.

Cervids and raccoon dogs as wildlife sentinels for the geographical distribution of tick-borne encephalitis virus and Francisella tularensis in Denmark.

Antibody Response to Pertussis Vaccine Among Children and Adolescents in Croatia: A Cross-Sectional Prevalence Study

Background/Objectives: The current national vaccination program does not completely control the transmission of Bordetella pertussis in Croatia. This cross-sectional seroprevalence study aimed to measure the prevalence of IgG antibodies to pertussis toxin (IgG-anti-PT) in regularly vaccinated Croatian children of 6–18 years of age and to estimate the duration of pertussis vaccine-induced immunity elicited by the National Immunization Program (NIP) with respect to the transition from a mixed acellular pertussis (DTaP) and whole-cell pertussis (DTwP) vaccine regimen to a DTaP regimen. Materials and Methods: Single-serum IgG-anti-PT concentrations were measured using a commercial enzyme-linked immunosorbent assay (ELISA) and analyzed in twelve age groups from 2020 to 2023. According to the manufacturer’s classification, IgG-anti-PT concentrations of <40 IU/mL, 40–100 IU/mL, and >100 IU/mL were considered negative, borderline, and positive, respectively. Results: In total, 1314 sera samples were collected and analyzed. Most subjects had an IgG-anti-PT concentration < 40 IU/mL (95.1%). This study sample’s IgG-anti-PT geometric mean concentration (GMC) was very low. Despite different vaccination backgrounds, the waning of IgG-anti-PT concentration was observed in Croatian children and adolescents. Discussion: In the present study, 0.53% of subjects were seropositive (>100 IU/mL). Regardless of the low quantity of IgG-anti-PT, we estimated that a degree of protection against pertussis persisted for at least 8–9 years based on a small increase in IgG-anti-PT GMC in 15–18-year-olds, indicative of an ongoing B. pertussis circulation in Croatia. Although introducing a booster pertussis vaccine could be suitable for young adolescents to strengthen their immunity, before such a recommendation, it would be useful to initiate further research to complement the results obtained in this study.

Serum neurofilament light chain as a potential biomarker in restless legs syndrome: a cross-sectional study

ABSTRACT Objective Neurofilament light chain (NfL) has emerged as a promising biomarker for several neurological diseases. Therefore, we investigated its serum levels and their association with disease characteristics, including duration, severity, and medication use in patients with restless legs syndrome (RLS). Method This cross-sectional prospective study included 71 RLS patients and 70 healthy controls. RLS patients were characterized based on disease duration, severity, and medication use. NfL levels were quantified using commercial enzyme-linked immunosorbent assay kits. Result No significant differences in NfL levels were observed between RLS patients and controls (p > 0.05). Furthermore, the levels were not significantly associated with disease duration or severity in RLS patients (p > 0.05). Conclusion These findings do not support the use of NfL as a biomarker for RLS. Further large-scale studies are needed to evaluate its role in RLS.

Does serum Gas6 level change in active uveitis?

The aim of this study was to investigate serum Growth Arrest-Specific Protein 6 (Gas6) levels in the active and inactive periods of uveitis. In this study, serum Gas6 levels were evaluated in 21 patients during active and inactive periods. After measuring serum Gas6 levels in the active phase, the serum Gas6 test was repeated in the inactive period. Commercial Enzyme-Linked Immunosorbent Assay (ELISA) kits (Gas6, WKEA Med Supplies Corporation, NY, USA) were used to measure Gas6 levels. Plasma concentrations were analyzed with an ELISA reader at 450 nm following the manufacturer's instructions. In the study, the mean age of 21 patients was 33 (7-62) years. The mean follow-up period was 30.05 ± 18.76 months. While the average Gas6 value measured during active uveitis attacks was 1.02 ± 0.39 ng/mL (range: 0.54-2.12), the Gas6 value during the passive period was 0.71 ± 0.23 ng/mL (range: 0.39-1.17). The Gas6 level during active uveitis attacks was significantly higher than during the passive period (p = 0.04). The findings of this study suggest a notable elevation in serum Gas6 levels across all cases of active uveitis, irrespective of the underlying etiology, whether infectious or noninfectious. To successfully integrate serum Gas6 levels into the diagnostic and follow-up protocols for active uveitis, additional comprehensive investigations are imperative.

The prevalence of rotavirus infection among Congolese children younger than 5 years hospitalized for gastroenteritis 10 years after introduction of rotavirus vaccination.

Rotavirus A (RVA) remains the primary cause of acute severe gastroenteritis associated with high rates of childhood hospitalization and mortality worldwide. The prevalence of RVA infection varies within low-income countries. In addition, its genetic diversity may vary among regions and may affect its prevalence. To control the emergence of new strains of RVA circulating in the Republic of Congo, it is essential to know the diversity of both G and P genotypes, which could render the vaccine less effective. Therefore, this study aimed to determine the prevalence and genotype diversity of RVA strains in children who were hospitalized, whether vaccinated or not. Moreover, the potential risk factors of disease severity are identified. The study was conducted from April 2022 to March 2023. Stool samples were collected from children younger than 5 years, hospitalized in a pediatric ward for acute gastroenteritis, and a commercial enzyme-linked immunosorbent assay (ELISA) was used to detect RVA cases. In parallel, a multiplex reverse transcription-polymerization chain reaction (RT-PCR) was performed for RVA detection and genotyping. All samples with ambiguous multiplex RT-PCR results were subjected to sequencing. A total of 227 children hospitalized were enrolled and tested for RVA infection. Using ELISA and PCR, 59 (26%) and 131 (57.7%) individuals were found to be infected with RVA, respectively. All individuals with a positive ELISA test result were confirmed as RVA-positive by PCR. Of the 98 children with documented histories of RVA vaccination, 60% presented with RVA infection. The occurrence of vomiting on more than three occasions within a 24-hour period and the time between vaccination and sample collection were found to be associated with RVA infection. RVA genotyping revealed six P types (P[4]; P[6]; P[8]; P[9]; P[10]; and P[11]). The predominant genotypes were (P[4] 15.3%; P[6] 13.7%; P[8] 22.1%; P[9] 14.5%). Among the eight G types, the most prevalent were G3 (13.7%), G4 (12.2%), and G1 (6.9%). No specific genotype distribution was discernible as a function of vaccination history. Compared with the findings of our study before the implementation of rotavirus vaccination, in this report, we observed a roughly 20% decreased prevalence of RVA infection in children hospitalized. The results suggest that in Brazzaville at least, 10 years of rotavirus vaccination in the Republic of Congo have had a substantial effect, despite the reported reduced efficacy of the vaccines in low- and middle-income countries. The findings thus support enhanced efforts to increase coverage through national vaccination programs.

Inflammatory and Analgesic Profiles in Intervertebral Disc Herniation: Variability with Respect to Neurological Deficit.

Disc herniation is both a mechanical and biochemical process in which contact between intervertebral discs and spinal nerves causes compression, chemical irritation, inflammation, and pain. The inflammatory process is known to vary depending on pain duration, herniation type, and pain severity, but the relationship with neurological deficits remains unknown. This study aimed to compare individuals with lumbar disc herniation with and without neurological deficits (WND/WOND) and healthy individuals in terms of serum levels of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 4 (IL-4), interleukin 1 beta (IL-1β), beta-endorphin, anandamide, and 2-arachidonoylglycerol (2-AG). The study included 37 lumbar disc herniation patients WND (22 female, 15 male), 37 patients WOND (22 female, 15 male), and 35 healthy individuals (18 female, 17 male). TNF-α, IL-6, IL-4, IL-1β, beta-endorphin, anandamide, and 2-AG serum levels were analyzed using commercial enzyme-linked immunosorbent assay kits. There was no difference in TNF-α levels between the WOND, WND, and control groups (P = 0.383). The WOND and WND groups showed significantly higher expression of IL-1β (P < 0.001) and IL-4 (P = 0.034, P < 0.001) when compared with healthy controls. IL-6 expression was lower in the WND group than in the control group (P < 0.001). Beta-endorphin, anandamide, and 2-AG levels did not differ significantly between the WOND, WND, and control groups (P = 0.888, P = 0.247, P = 0.433, respectively). This study is the first to demonstrate the effect of the presence of a neurological deficit on serum biomarker levels in patients with lumbar disc herniation. Even in the presence of neurological deficit, decreased levels of proinflammatory cytokines and increased levels of anti-inflammatory cytokines indicated regression of the disc herniation. These results suggest the need to establish new and improved treatment protocols to target the inflammatory process in individuals with lumbar disc herniation.

Plasma vinculin, β-catenin, E-cadherin levels in children with autism spectrum disorder

Objectives β-catenin, E-cadherin, and vinculin are essential components of adherens junctions. They play critical roles in both the blood-brain barrier (BBB) and the intestinal barrier. Increased intestinal and BBB permeability has been suggested to play a role in autism spectrum disorder (ASD). The aim of this study is to determine whether there is a difference in the levels of these molecules between individuals diagnosed with ASD and healthy controls. Methods A total of 40 children with ASD and 40 controls aged 2–12 years were enrolled in this study. Plasma levels of biochemical variables were determined using commercial enzyme-linked immunosorbent assay kits. Results The plasma β-catenin level was significantly higher in the ASD group compared to the control group. However, no significant difference was found between the groups in terms of plasma vinculin and E-cadherin levels. Conclusions These findings suggest that β-catenin may play a role in the pathogenesis of ASD.

Agarose Gel-Coated Nanochannel Biosensor for Detection of Prostate-Specific Antigen in Unprocessed Whole Blood Samples.

Solid-state nanopore/nanochannel biosensors have rapidly advanced due to their high sensitivity, label-free detection, and fast response. However, detecting biomarkers directly in complex biological environments, particularly whole blood, remains challenging because of nonspecific protein adsorption and nanopore/nanochannel clogging. Here, a DNA aptamer functionalized nanochannel biosensor is developed with excellent antifouling properties, achieved by coating the nanochannel surface with agarose gel. This gel coating effectively mitigates fouling in diverse biological environments while maintaining comparable sensitivity to uncoated nanochannels for detecting prostate-specific antigen (PSA) in buffer solutions within 20 min. The biosensor exhibits a detection limit of 1 ngmL-1 for PSA in human serum, matching the performance of commercial enzyme-linked immunosorbent assay (ELISA) kits. Importantly, it successfully differentiates whole blood samples from prostate cancer patients and healthy individuals. The superior antifouling behavior is attributed to the electrically neutral, highly hydrophilic nature, and porous structure of the agarose gel, which prevents the adsorption of large biomolecules while facilitating the diffusion of PSA for aptamer-based capture. This DNA aptamer functionalized nanochannel biosensor with agarose gel coating offers reliable protein detection in complex biological environments, showing great promise in biomedical applications.

Seroprevalence of Human T-lymphotropic Virus Infections among Pregnant Women in Urmia, Northwest Iran

Introduction: The human T-lymphotropic virus (HTLV)-1/2 is a retrovirus that can cause adult T-cell leukemia/lymphoma, tissue-necrotizing lymphadenitis, and tropical spastic paraparesis. The purpose of this study was to determine the prevalence of HTLV infection in pregnant women receiving care in Urmia, sited in northwest Iran. Materials and Methods: A cross-sectional study was conducted on 86 pregnant women in Urmia between May and September 2014. Following interviews and blood sample collection, the participants were screened for IgG antibodies against HTLV-1/2 using commercial enzyme-linked immunosorbent assays. Results: The average age of the participants was 25.56 ± 5.30 years, with 3 individuals (3.49%) reporting a history of blood transfusion and 18 patients (20.93%) having experienced previous abortions. Serological testing did not reveal any evidence of HTLV-1/2 infection in the study population. Conclusion: While screening for HTLV-1/2 infection in pregnant women holds significance, it appears that during the study period, this issue was not recognized as a major health concern among pregnant women in Urmia. This observation aligns with findings from other research in Iran, where awareness and emphasis on HTLV-1/2 screening in pregnant populations remain relatively low.

Correlation of BP180, BP230, and type VII collagen antibody titers in serum, blister fluid, erosion, and saliva in pemphigoid diseases.

Autoantibodies, including anti-BP180 and anti-BP230 antibodies in bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP), and anti-type VII collagen (COL7) antibodies in epidermolysis bullosa acquisita (EBA), are well characterized. Enzyme-linked immunosorbent assays (ELISAs) for the detection of these antibodies in the serum are valuable for diagnosis. Previous studies have indicated that anti-BP180 and anti-BP230 antibodies in blister fluid and saliva can be detected using ELISA. The aim of this study was to detect anti-BP180, anti-BP230, and anti-COL7 antibodies in several types of samples, including blister fluid, an erosive surface swab, and saliva, by ELISAs and to compare the titers of these antibodies between different types of samples. Thirty-three patients with BP/MMP, two patients with EBA, and 13 patients with non-pemphigoid diseases were included in this study. Samples were collected from each patient and analyzed using commercial ELISA kits. In the cases of BP/MMP, the mean ± standard deviation indices of BP180 ELISA were 411.9 ± 538.3, 253.5 ± 333.3, 2.360 ± 1.714, and 1.599 ± 1.262, and those of BP230 ELISA were 27.73 ± 37.65, 20.52 ± 30.04, 0.486 ± 0.7915, and 0.346 ± 0.4373, from sera, blister fluids, erosive surface swabs, and saliva, respectively. The indices of BP180 and BP230 ELISAs using serum were significantly correlated with those of BP180 and BP230 ELISAs using blister fluid (r = 0.9342 and r = 0.9882), an erosive surface swab (r = 0.7586 and r = 0.9332), and saliva (r = 0.5731 and r = 0.6147), respectively. This study revealed that autoantibodies were detectable in blister fluids, erosive surfaces, and saliva, and their correlation with serum titers in pemphigoid diseases was highest in blister fluid. In summary, blister fluid can be a minimally invasive sample alternative to serum for the detection of pemphigoid-related antibodies.

Serological evidence of Crimean-Congo haemorrhagic fever in domestic animals from eight regions of Namibia.

Serological evidence of Crimean-Congo haemorrhagic fever in domestic animals from eight regions of Namibia.

Potency of two chimeric vaccine candidates derived from the classical swine fever GPE- vaccine strain against a circulating virus strain isolated in Japan.

Potency of two chimeric vaccine candidates derived from the classical swine fever GPE- vaccine strain against a circulating virus strain isolated in Japan.

The evaluation of anti-diphtheria toxoid antibodies after 5 years with the primary Tetanus-Diphtheria vaccine in persons aged 6-25 years in Kon Tum, Vietnam: a follow-up study.

Diphtheria is a serious infectious disease although being vaccine-preventable. 5-year follow-up study aimed to evaluate the persistence of IgG antibodies to diphtheria toxoid after Tetanus-diphtheria primary immunization for persons aged 6-25 years in Kon Tum, Viet Nam. Blood samples were obtained from 128 healthy persons aged 6-25 years collected in 2021. Samples were tested for diphtheria toxoid antibodies by commercial Anti-Diphtheria Toxoid IgG Enzyme-Linked Immunosorbent Assay (ELISA). One month after Td primary vaccination, 92.2% of participants were fully protected against diphtheria (> 0.1 IU/mL). GMCs increased from 0.04 to 0.91 IU/mL at one month, which were maintained in nearly 90% of vaccinees at 5 years. Among children aged 6-10 years, 97.3% had full protection at 1 month after primary vaccination, maintained in 94.6% at 5 years. Among adolescents and adults, 81.0% to 98.5% had full protection at 1 month after vaccination, which were maintained from 72.7% to 96.7% at 5 years. Although, the antibodies slightly declined approximately 5 years post-vaccination, but remained several-fold higher than pre-vaccination. Td vaccine provides long-lasting protective antibodies against diphtheria. These data may inform discussion of the need for Td booster vaccinations among high-risk persons.