Nomogram for predicting in-hospital mortality in trauma patients undergoing resuscitative endovascular balloon occlusion of the aorta: a retrospective multicenter study

Recently, resuscitative endovascular balloon occlusion of the aorta (REBOA) had been introduced as an innovative procedure for severe hemorrhage in the abdomen or pelvis. We aimed to investigate risk factors associated with mortality after REBOA and construct a model for predicting mortality. This multicenter retrospective study collected data from 251 patients admitted at five regional trauma centers across South Korea from 2015 to 2022. The indications for REBOA included patients experiencing hypovolemic shock due to hemorrhage in the abdomen, pelvis, or lower extremities, and those who were non-responders (systolic blood pressure (SBP) < 90 mmHg) to initial fluid treatment. The primary and secondary outcomes were mortality due to exsanguination and overall mortality, respectively. After feature selection using the least absolute shrinkage and selection operator (LASSO) logistic regression model to minimize overfitting, a multivariate logistic regression (MLR) model and nomogram were constructed. In the MLR model using risk factors selected in the LASSO, five risk factors, including initial heart rate (adjusted odds ratio [aOR], 0.99; 95% confidence interval [CI], 0.98-1.00; p = 0.030), initial Glasgow coma scale (aOR, 0.86; 95% CI 0.80-0.93; p < 0.001), RBC transfusion within 4 h (unit, aOR, 1.12; 95% CI 1.07-1.17; p < 0.001), balloon occlusion type (reference: partial occlusion; total occlusion, aOR, 2.53; 95% CI 1.27-5.02; p = 0.008; partial + total occlusion, aOR, 2.04; 95% CI 0.71-5.86; p = 0.187), and post-REBOA systolic blood pressure (SBP) (aOR, 0.98; 95% CI 0.97-0.99; p < 0.001) were significantly associated with mortality due to exsanguination. The prediction model showed an area under curve, sensitivity, and specificity of 0.855, 73.2%, and 83.6%, respectively. Decision curve analysis showed that the predictive model had increased net benefits across a wide range of threshold probabilities. This study developed a novel intuitive nomogram for predicting mortality in patients undergoing REBOA. Our proposed model exhibited excellent performance and revealed that total occlusion was associated with poor outcomes, with post-REBOA SBP potentially being an effective surrogate measure.

Hemostatic effect of fibrinogen concentrate on traumatic massive hemorrhage: a propensity score matching study

Background

Fibrinogen concentrate (FC) can be administered during massive transfusions to manage trauma-induced coagulopathy. However, its effectiveness in survival remains inconclusive due to scarce high-level evidence. This study aimed to investigate the hemostatic effects of FC regarding mortality in massive hemorrhage caused by trauma.

Methods

This retrospective study analyzed 839 patients who received massive transfusions (red blood cells (RBCs) ≥5 units in 4 hours or ≥10 units in 24 hours) at a level I trauma center between 2015 and 2022. Patients who were transferred to other hospitals or were deceased upon arrival, suffered or died from severe brain injury, and were aged 15 years or less were excluded (n=334). 1:2 propensity score matching was performed to compare the 'FC (+)' group who had received FC in 24 hours (n=68) with those who had not ('FC (-)', n=437). The primary outcome was mortality, and the secondary outcomes included transfusion volume.

Results

The variables for matching included vital signs, injury characteristics, prehospital time, implementation of resuscitative endovascular balloon occlusion of the aorta, and blood gas analysis results. The administration of FC did not significantly reduce or predict mortality (in-hospital, 24 hours, 48 hours, or 7 days). The FC (-) group received more units of RBC (25.69 units vs. 16.71 units, p<0.001, standardized mean difference [SMD] 0.595), fresh frozen plasma (16.79 units vs. 12.91 units, p=0.023, SMD 0.321), and platelets (8.76 units vs. 5.46 units, p=0.002, SMD 0.446) than the FC (+) group.

Conclusion

The use of FC did not show survival benefits but reduced transfusion requirements in traumatic massive hemorrhages, highlighting a need for future investigations. In the future, individualized goal-directed transfusion with FC may play a significant role in treating massive bleeding.

Level of evidence

IV, retrospective study having more than one negative criterion.

The temporary abdominal closure techniques used for trauma patients: a systematic review and meta-analysis

Purpose

The choice of temporary abdominal closure (TAC) method affects the prognosis of trauma patients. Previous studies on TAC are challenging to extrapolate due to data heterogeneity. We aimed to conduct a systematic review and comparison of various TAC techniques.

Methods

We accessed web-based databases for studies on the clinical outcomes of TAC techniques. Recognized techniques, including negative-pressure wound therapy with or without continuous fascial traction, skin tension, meshes, Bogota bags, and Wittman patches, were classified via a method of closure such as skin-only closure vs. patch closure vs. vacuum closure; and via dynamics of treatment like static therapy (ST) vs. dynamic therapy (DT). Study endpoints included in-hospital mortality, definitive fascial closure (DFC) rate, and incidence of intraabdominal complications.

Results

Among 1,065 identified studies, 37 papers comprising 2,582 trauma patients met the inclusion criteria. The vacuum closure group showed the lowest mortality (13%; 95% confidence interval [CI], 6%-19%) and a moderate DFC rate (74%; 95% CI, 67%-82%). The skin-only closure group showed the highest mortality (35%; 95% CI, 7%-63%) and the highest DFC rate (96%; 95% CI, 93%-99%). In the second group analysis, DT showed better outcomes than ST for all endpoints.

Conclusion

Vacuum closure was favorable in terms of in-hospital mortality, ventral hernia, and peritoneal abscess. Skin-only closure might be an alternative TAC method in carefully selected groups. DT may provide the best results; however, further studies are needed.

Delayed Chylothorax Following Blunt Chest Trauma Treated with Repeated Lymphangiography: A Case Presentation

Chylothorax is mostly iatrogenic, with blunt chest trauma being a rare cause. Treatment depends on the volume of drainage. Specifically, conservative treatment, such as total parenteral nutrition and pleural drainage, is performed in cases of low daily output (< 500 mL/day). Patients with persistent chylothorax despite medical treatment or with high daily output (> 1-1.5 L/day) are candidates for surgical or radiological intervention. We present a case of delayed-onset chylothorax after blunt trauma caused by thoracic spine fractures, in which persistent chylothorax was successfully managed with repeated lymphangiography with lipiodol when other treatment modalities failed. The case is peculiar in that the chylothorax occurred 40 days after the initial traumatic event and was treated with lipiodol injection, despite maintaining moderate to high daily output.

Feasibility and Clinical Outcomes of Resuscitative Endovascular Balloon Occlusion of the Aorta in Patients with Traumatic Shock: A Single-Center 5-Year Experience

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has recently gained popularity as an adjunct to resuscitation of patients with traumatic shock. However, the effectiveness of REBOA is still debated because of inconsistent indications across centers and the lack of medical records. The purpose of this study was to investigate the effectiveness and feasibility of REBOA by analyzing clinical results from a single center.

Methods

This study included 96 patients who underwent REBOA between August 2016 and September 2021 at a regional trauma center according to the center's treatment algorithm for traumatic shock. Medical records, including the time of the decision to conduct the REBOA procedure, time of operation, type of aortic occlusion, and clinical outcomes, were collected prospectively and analyzed retrospectively. Patients were classified by REBOA protocol (group 1, 2, or 3) and survival status (survivor or non-survivor) for analysis.

Results

The overall success rate of the procedure was 97.9%, and the survival rate was 32.6%. In survivors, blood pressure was higher than in non-survivors both before the REBOA procedure (p=0.002) and after aortic occlusion (p=0.03). The total aortic occlusion time was significantly shorter (p=0.001) and the proportion of partial aortic occlusion was significantly higher (p=0.014) among the survivors. The non-survivors had more acidosis (p<0.001) and higher lactate concentrations (p<0.001) than the survivors.

Conclusion

REBOA may be a feasible bridge therapy for resuscitation of patients with traumatic shock. Prompt and accurate decision-making to perform REBOA followed by damage control surgery could improve survival rates and clinical outcomes.

Exercise-induced traumatic muscle injuries with active bleeding successfully treated by embolization: three case reports

Muscle injuries caused by indirect trauma during exercise are common. Most of these injuries can be managed conservatively; however, further treatment is required in extreme cases. Although transcatheter arterial embolization is a possible treatment modality, its role in traumatic muscle injuries remains unclear. In this case series, we present three cases of exercise-induced muscle hemorrhage treated by transcatheter arterial embolization with successful outcomes. The damaged muscles were the rectus abdominis, adductor longus, and iliopsoas, and the vascular injuries were accessed via the femoral artery during the procedures.

Transsplenic Ultrasound-Guided Balloon Positioning During a Zone 1 Resuscitative Endovascular Balloon Occlusion of the Aorta: A Case Report

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an effective resuscitative modality to temporize noncompressible truncal hemorrhage. Confirming the proper position of the balloon catheter in the target aortic zone is vital. Currently, there is a need for nonradiographical methods. This would overcome the drawbacks of conventional imaging modalities, such as fluoroscopy. Several studies have suggested ultrasound-guided visualization via subxiphoid, transperitoneal, or transesophageal views as an alternative to conventional imaging methods. However, such views are easily obscured in emergency settings. Herein, we report the case of a 70-year-old patient who was successfully resuscitated by REBOA under the guidance of transsplenic ultrasound. REBOA was safely performed using transsplenic visualization without fluoroscopy.

Laparoscopic repair of combined extra- and intraperitoneal bladder ruptures in a patient with blunt trauma: Use of the bladder suspension method

Urinary bladder rupture is commonly due to blunt abdominal trauma rather than penetrating trauma. Intraperitoneal bladder rupture (IBR) is a concrete indication of surgical management. On the other hand, surgeons should perform surgeries in patients with extraperitoneal bladder rupture (EBR) solely in complicated cases. Uncomplicated EBR is managed conservatively. Laparoscopic repair is safe and effective for the treatment of IBR. However, there are no contemporary guidelines on the application of laparoscopy for the management of EBR. Herein, we describe a case of combined EBR and IBR in a hemodynamically stable 45-year-old patient who sustained injuries after falling. Intravesical repair of EBR and intracorporeal repair of IBR with the bladder suspension method were successfully performed with laparoscopy. This is a rare case describing the feasibility of laparoscopic suturing for combined EBR and IBR in a patient with blunt trauma.

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Laparoscopic repair of extra- and intraperitoneal bladder rupture is feasible.

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The bladder suspension method is recommended in such repair.

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Knowledge of the indications for surgical repair of bladder is required.

Laparoscopic Repair of Traumatic Intraperitoneal Bladder Rupture: A Case Series

Bladder injury is uncommon in blunt abdominal trauma. The injury can be life-threatening if not treated properly. Thus, timely and accurate diagnosis is critical. Traumatic intraperitoneal bladder rupture (TIBR) can be managed laparoscopically in patients who are hemodynamically stable. In this case series, we present 3 patients who underwent laparoscopic repair of TIBR performed by a single surgeon. In addition, we address useful technical tips that would facilitate the generalized use of laparoscopy for treating TIBR.

Analysis of local invasion and regional spread in malignant sublingual gland tumour: Implications for surgical planning

Malignant tumours arising from the sublingual glands are very rare, and the extent and frequency of local invasion or regional spread in malignant sublingual gland tumour (MSLT) has not been fully studied due to the disease rarity. To provide comprehensive features of local and regional spread of MSLT, we reviewed 20 surgical cases for detailed pathological analyses among 26 cases diagnosed as having primary MSLT. Adenoid cystic carcinoma (ACC) was the most common pathological subtype, followed by mucoepidermoid carcinoma. Disease-free and overall survivals at 5 years were 76.1 % and 77.7 %, respectively. High-grade malignant tumours and grade 2-3 ACC accounted for 41.7 % and 85.7 %. Clinical and pathological extraparenchymal extensions were found in 34.6 % and 80.0 %, respectively. Tumour invasion to the lingual nerve and submandibular gland/ductal system were also detected in 40.0 % and 28.6 %. The incidences of lingual nerve invasion in ACC and ACC ≥4 cm were 30.8 % and 42.9 %. Regional nodal involvement occurred in seven of 26 cases, and all metastatic lymph nodes were found in neck levels Ib and IIa. In summary, a significant portion of MSLT cases consisted of high-grade tumours and grade 2-3 ACC; therefore local invasion into adjacent structures should be cautiously evaluated in cases of MSLT.

Impacts of Social Distancing During the COVID-19 Outbreaks in Korea: Level 1 Trauma Center Data of Domestic Incidents and Intentional Injury

OBJECTIVES

As a protective measure to slow down the transmission of coronavirus disease 2019 in Korea, social distancing was implemented from February 29th, 2020. This study aimed to evaluate the prevalence of domestic incidents and intentional injury during March 2020 when social distancing was in effect.

METHODS

There were 12,638 patients who visited the Level 1 trauma center of Chungnam province with injuries from domestic incidents, familial discord, and intentional injury. The prevalence of injuries during March 2020 was compared with the average of the previous 5 years, and the average for every March between 2015 and 2019.

RESULTS

The prevalence of domestic incidents in March 2020 was significantly higher than the 5-year average, and the average for every March from 2015 to 2019 (p < 0.001). Familial discord (p = 0.002) and intentional injury (p = 0.031) were more frequently observed in March 2020. Adolescents showed a markedly higher level of intentional injury in March 2020 than in both the 5-year average (p = 0.031), and average for every March over the previous 5 years (p = 0.037).

CONCLUSION

The prevalence of domestic incidents and intentional injury were significantly higher during the period of social distancing in Korea. There is a need for social consensus, better policies, and psychological support services, especially if faced with a second or third wave of coronavirus disease.

Successful Treatment of Life-Threatening Small Bowel Bleeding With Thalidomide After Living Donor Kidney Transplantation: A Case Report

Gastrointestinal bleeding after kidney transplantation is a complication that can occur from immunosuppressant use. We present a case of refractory small bowel bleeding treated successfully with thalidomide after multiple failed attempts of conventional treatment. A 65-year-old male patient with diabetic nephropathy underwent living donor kidney transplantation. The surgery was uneventful, however, he developed immunosuppressant-induced melena with unstable vital signs 11 days later. There were a total of 4 bleeding episodes until the 90th postoperative day, and he received a total of 290 units of red blood cell transfusion during this period. Endoscopic clipping, transarterial embolization, and 2 surgical interventions failed to stop the bleeding. A trial of thalidomide 100 mg per day finally stopped the bleeding and the patient was discharged on the 110th postoperative day with a functioning renal graft. This case shows that thalidomide can be a safe option to treat immunosuppressant-induced refractory gastrointestinal bleeding in the setting of kidney transplantation. Additionally, this is the first case that reports the survival of a renal graft after more than 3000 mL of transfusion.

Structural and electronic transformation pathways in morphotropic BiFeO3

Phase boundaries in multiferroics, in which (anti-)ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetism and electronic properties by external electric fields through switching of the polarization in the material. It has been shown that the strain-driven morphotropic phase boundaries in a single-phase multiferroic such as BiFeO₃ (BFO) can exhibit distinct electronic conductivity. However, the control of ferroelectric and phase switching and its correlation with phase boundary conductivity in this material has been a significant challenge. Supported by a thermodynamic approach, here we report a concept to precisely control different switching pathways and the associated control of electronic conductivity in mixed phase BFO. This work demonstrates a critical step to control and use non-volatile strain-conductivity coupling at the nanoscale. Beyond this observation, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic and ferroelectric order in multiferroic materials.

Serum IgE elevation correlates with blood lead levels in battery manufacturing workers

Lead (Pb), an occupational and environmental toxicant, is known to induce immunomodulatory effects resulting in lowered resistance to infectious micro-organisms and altered levels of immunoglobulins in humans. Preferential activation of type-2 helper T cells and inhibition of type-1 T-cell activation is considered a cellular mechanism for the Pb-induced immune alteration, which has not been investigated well in humans. Lead's influence on in vivo balance between type-1 and type-2 activities was assessed among workers exposed to Pb through battery manufacturing in Korea. Serum IgE levels were significantly higher in the workers with a blood Pb level (PbB) of ≤30 μg/dL than in the workers with a PbB of <30 μg/dL. Furthermore, the serum IgE concentrations significantly correlated with PbB although no significant relationship between PbB and serum interleukin-4 or interferon gamma levels was observed. The present study indicates that elevation of IgE levels may be an immunologic index for Pb-induced in vivo toxicities, potentially involved with progression of various allergic diseases in humans.

Associations among SPARC mRNA expression in adipose tissue, serum SPARC concentration and metabolic parameters in Korean women

OBJECTIVE

Secreted protein acidic and rich in cysteine (SPARC) is expressed in most tissues and is also secreted by adipocytes. The associations of SPARC mRNA expression in visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAT), serum SPARC concentration, and metabolic parameters in Korean women are investigated.

DESIGN AND METHODS

This is a cross-sectional study. Fifty-eight women were recruited, of whom 15 women who underwent bariatric surgery for morbid obesity (BMI mean ± SD: 40.2±5.7 kg/m(2) ), 16 who underwent metabolic surgery for type 2 diabetes (BMI: 28.9±4.5 kg/m(2) ), and, as a control group, 27 who underwent gynecological surgery (BMI: 22.7±2.4 kg/m(2) ). Anthropometric variables, metabolic parameters, SPARC mRNA expression in adipose tissue, and serum SPARC concentration were measured.

RESULTS

In all subjects, SPARC mRNA expression was significantly higher in SAT than in VAT. Serum SPARC concentrations (mean ± SE) in morbidly obese subjects, subjects with type 2 diabetes, and normal weight subjects were 267.3±40.2 ng/mL, 130.4±33.0 ng/mL, and 53.1±2.8 ng/mL, respectively. SPARC mRNA in SAT was significantly correlated with BMI, whereas SPARC mRNA in VAT was significantly correlated with BMI and VAT area. Serum SPARC concentration was significantly correlated with BMI, waist circumference, total adipose tissue area, and SAT area. After BMI adjustment, serum SPARC concentration was significantly correlated with fasting insulin concentration and HOMA-IR score. Multivariate regression analysis showed that BMI and HOMA-IR were independently associated with serum SPARC concentration.

CONCLUSIONS

Serum SPARC concentration is significantly correlated with obesity indices and might be influenced by insulin resistance. These findings suggest that SPARC may contribute to the metabolic dysregulation associated with obesity in humans.

Design and fabrication of label-free biochip using a guided mode resonance filter with nano grating structures by injection molding process

This paper introduces technology to fabricate a guided mode resonance filter biochip using injection molding. Of the various nanofabrication processes that exist, injection molding is the most suitable for the mass production of polymer nanostructures. Fabrication of a nanograting pattern for guided mode resonance filters by injection molding requires a durable metal stamp, because of the high injection temperature and pressure. Careful consideration of the optimized process parameters is also required to achieve uniform sub-wavelength gratings with high fidelity. In this study, a metallic nanostructure pattern to be used as the stamp for the injection molding process was fabricated using electron beam lithography, a UV nanoimprinting process, and an electroforming process. A one-dimensional nanograting substrate was replicated by injection molding, during which the process parameters were controlled. To evaluate the geometric quality of the injection molded nanograting patterns, the surface profile of the fabricated nanograting for different processing conditions was analyzed using an atomic force microscope and a scanning electron microscope. Finally, to demonstrate the feasibility of the proposed process for fabricating guided mode resonance filter biochips, a high-refractive-index material was deposited on the polymer nanograting and its guided mode resonance characteristics were analyzed.

Effect of diesel exhaust particles and their components on the allergen-specific IgE and IgG1 response in mice

Increased antigen-specific IgE expression is a hallmark of the allergic response in mice. IgG1 may also be involved. Co-injection of mice with diesel exhaust particles (DEP) and ovalbumin three times over a 2 week period lead to a rapid and marked elevation of ovalbumin-specific IgE, IgG1 and also IgG2a, compared with ovalbumin alone. When DEP were injected 1 day before or after ovalbumin on each occasion, their adjuvant effect was considerably muted, suggesting that the adjuvant effect of DEP is short-lived, or that a physical interaction between ovalbumin and DEP is required. DEP were extracted with methylene chloride. Both the resulting core carbon particles and the organic extract enhanced ovalbumin specific IgE and IgG1 levels. Thus the adjuvant effect of DEP in this model is due both to the physical and the chemical attributes of the particles. The tricyclic hydrocarbons phenanthene (the most prevalent polycyclic aromatic hydrocarbon in DEP) and anthracene were both capable of enhancing antigen-specific IgE and IgG1 production. The phenolic antioxidant, butylated hydroxyanisole, which can affect gene expression via the antioxidant responsive element (ARE), had a lesser effect. Two agonists for the aryl hydrocarbon receptor, 3-methychloranthrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin, either were without effect or suppressed the response, suggesting that DEP adjuvancy may not be mediated by this receptor.

Altered serum cytokine and immunoglobulin levels in the workers exposed to antimony

1 Antimony (Sb), an industrial and environmental toxicant, is known to cause dermatitis and pulmonary inflammations, but the immunomodulatory effects of environmental or occupational exposure to Sb have not been reported. To initiate investigation of Sb-induced alterations of the immune system, the concentrations of the IgG subclasses, IgE, interleukin-2, interferon-gamma, and interleukin-4 in sera obtained from workers exposed to Sb through antimony trioxide manufacture were determined and compared with those of control subjects. 2 The serum levels of IgG1, an immunoglobulin involved in host defense against many microbial infections, were significantly lower in the sera of Sb-exposed individuals than the controls. The serum concentrations of IgE, an immunoglobulin mediating allergic hypersensitivity, also were lower in the Sb-exposed workers than the controls. In addition, the levels of interleukin-2 and interferon-gamma, multifunctional cytokines for T-cell mediated immunity, were lowered in the factory workers. 3 A significant positive correlation between IgG4 and urine Sb levels was found among the Sb-exposed workers, indicating a possible role of IgG4 in Sb-mediated pulmonary or skin pathogenesis. 4 The present study provides the first report on immune alterations induced by occupational exposure to Sb and suggests that Sb exposure disturbs immunohomeostasis in humans observed as a function of aberrant serum cytokine and immunoglobulin levels, which could influence health.

Differential effects of lead and cAMP on development and activities of Th1- and Th2-lymphocytes

Lead (Pb) is known to have detrimental effects on the central nervous, hematopoietic, renal, and immune systems. Herein, it is demonstrated that Pb can skew T cell reactivities by preferentially enhancing the development of Th2 cells and inhibiting the development of Th1 cells. When naive splenic CD4+ T cells from DO11.10 ovalbumin-specific transgenic (OVA-tg) mice or OVA-tg/RAG2-/- mice were developed in vitro in the presence of Pb, preferential skewing toward Th2 cells was evident. The Pb-driven skewing toward Th2 was blocked significantly in the presence of exogenous IL-12 or anti-IL-4 mAbs. Although Pb and dibutyryl cAMP (dbcAMP) appear to have similar effects on the development and reactivity of Th1 cells, unlike Pb, dbcAMP did not enhance Th2 development/activity. Further evidence of Pb's differential T cell effects was observed, in that regardless of the activation stimuli (Ag/APC; anti-CD3; PMA + ionomycin), the addition of PbCl2 consistently resulted in significant inhibition of IFN gamma production by a Th1 clone and in increased IL-4 production by a Th2 clone. In vitro addition of IL-12 overcame Pb's inhibition of Th1 cells. Th1 cells treated with a phosphodiesterase inhibitor had significantly elevated [cAMP]i levels following anti-CD3 activation in the presence of Pb, suggesting that Pb may inhibit Th1 development by enhancing adenylate cyclase activity and elevating the [cAMP]i level. Similar to Pb, a low concentration (10 microM) of dbcAMP inhibited IFN gamma production by Th1, which was prevented by IL-12; however, inhibition of protein kinase A activity by KT5720 did not reverse these effects. These results indicate that the environmental toxicant Pb can modify immune reactivities by significantly altering the differentiation of precursor or naive Th cells as well as by directly inhibiting Th1 cells and stimulating Th2 cells.

In vivo the environmental pollutants lead and mercury induce oligoclonal T cell responses skewed toward type-2 reactivities

An oligoclonal utilization of Vbetas has been reported for pathogenesis of several autoimmune diseases, anti-tumorigenic activity, and superantigen-regulation of thymic T cell development. Altered ratios of Th1 and Th2 cells also are observed in immunodysregulations, leading to impaired cell-mediated immunity with an increased incidence of infectious disease or cancer and/or aberrant immunity that could culminate with an autoimmune disease. Lead (Pb) and mercury (Hg) are known pollutants with immunodisrupting activities; Hg is known to cause autoimmune glomerulonephritis. Both metals are known to suppress host resistance to pathogens. To further evaluate the manner by which these metals cause in vivo immunomodulation, their in vivo effects on Vbeta expression were evaluated along with the Th1 and Th2 frequency. Exposure of BALB/c mice to PbCl2 or HgCl2 induced an oligoclonal response with increases of Vbeta 5+, Vbeta 7+, and Vbeta 13+ CD4+ splenic, but not thymic, T cells. A significantly skewed frequency of Pb-induced splenic Th2 cells expressing Vbeta 7 or Vbeta 13 over Th1 cells was determined by limiting dilution analysis, but this Th2 predominance was not observed with CD4+ T cells expressing Vbeta 8. DO11.10 transgenic mouse exposed to Pb and antigen also demonstrated a skewed type-2 response evidenced by significantly increased IgE levels, lowered IFN-gamma levels, and increased IgG1 and lowered IgG2a anti-OVA levels. Even in the absence of specific T cell responses to a Pb-induced antigen, due to the restricted T cell specificity in the transgenic mouse model, Pb still was able to skew the response toward type-2 reactivity. However, this skewing occurred only in the presence of antigen. Therefore, the Pb-induced oligoclonal T cell response in BALB/c mice which must be initiated by self-antigens and was predominately type-2 may be responsible for autoantibody production and the detrimental health effects associated with Pb exposure.

Lead differentially modifies cytokine production in vitro and in vivo

An imbalance between helper T cell type 1 (Th1) and helper T cell type 2 (Th2) activation can result in immunodysregulations leading to impaired cell-mediated immunity with an increased incidence of infectious disease or cancer and/or aberrant humoral immunity that may culminate with an autoimmune disease. Mercury, a heavy-metal toxicant, is known to induce renal autoimmunity characterized by a predominant Th2 response. Lead, another metal toxicant, causes enhanced B cell activities and impairs host resistance to several bacterial and viral infections. In addition, Pb was reported to enhance Th2 proliferation and inhibit Th1 proliferation. The differential effects of Pb on Th subset activation have been further investigated. In vitro IL-4 production by a Th2 clone was significantly increased by the addition of PbCl2, whereas IFN gamma production by a Th1 clone was decreased by the addition of PbCl2. When BALB/c mice were subcutaneously exposed to PbCl2, ex vivo Il-4 production by anti-CD3-stimulated splenic T cells was enhanced, but IFN gamma production was inhibited. Additionally, the plasma IL-4 and IgE levels of Pb-exposed mice were increased, and the plasma IFN gamma levels were significantly lowered in the absence of any additional exogenous antigen. In vitro, ex vivo, and in vivo treatment with HgCl2 produced similar findings. This study is the first report of the preferential activation of a Th2 response by Pb in vivo and suggests that PB, like Hg, may induce autoimmune responses by upsetting the balance between Th1- and Th2-like cells, which could enhance production of antibodies to self antigens.

Optimization of targeted RNA recombination and mapping of a novel nucleocapsid gene mutation in the coronavirus mouse hepatitis virus

We have recently described a method of introducing site-specific mutations into the genome of the coronavirus mouse hepatitis virus (MHV) by RNA recombination between cotransfected genomic RNA and a synthetic subgenomic mRNA (C. A. Koetzner, M. M. Parker, C. S. Ricard, L. S. Sturman, and P. S. Masters, J. Virol. 66:1841-1848, 1992). By using a thermolabile N protein mutant of MHV (Alb4) as the recipient virus and synthetic RNA7 (the mRNA for the nucleocapsid protein N) as the donor, we selected engineered recombinant viruses as heat-stable progeny resulting from cotransfection. We have now been able to greatly increase the efficiency of targeted recombination in this process by using a synthetic defective interfering (DI) RNA in place of RNA7. The frequency of recombination is sufficiently high that, with Alb4 as the recipient, recombinants can be directly identified without using thermal selection. The synthetic DI RNA has been used to demonstrate that the lesion in another temperature-sensitive and thermolabile MHV mutant, Alb1, maps to the N gene. Sequencing of the Alb1 N gene revealed two closely linked point mutations that fall in a region of the N molecule previously noted as being the most highly conserved region among all of the coronavirus N proteins. Analysis of revertants of the Alb1 mutant revealed that one of the two mutations is critical for the temperature-sensitive phenotype; the second mutation is phenotypically silent.

The antigen-limited nature of microtiter ELISAs requires partial depletion of IgG to permit reliable determination of rabbit serum IgA antibody activity

The antigen-limiting nature of microtiter ELISAs predicts that antibodies of minor classes may be underestimated when the same specimen contains large amounts of IgG antibodies specific for the same antigen. Such competitive inhibition can be diagnosed from ELISA titration plots. A method is described to eliminate the negative effects of this competition on the detection of IgA antibodies in rabbit serum. The detectability of rabbit serum antibodies to ovalbumin and bovine serum albumin is increased 10-fold by prior treatment of 1:100 dilutions of serum with 1% Cowan I S. aureus. High concns of S. aureus, e.g. 10%, completely deplete serum IgG without loss of IgA. However, concns higher than 1% do not lead to additional improvement in the detectability of IgA antibodies in the systems studied. The method is rapid, inexpensive and shows no non-specific depletion of IgA from either serum or bronchoalveolar lavage fluid.