Current vaccine strategies and novel approaches to combatting Francisella infection

Tularemia is caused by subspecies of Francisella tularensis and can manifest in a variety of disease states, with the pneumonic presentation resulting in the greatest mortality. Despite decades of research, there are no approved vaccines against F. tularensis in the United States. Traditional vaccination strategies, such as live-attenuated or subunit vaccines, are not favorable due to inadequate protection or safety concerns. Because of this, novel vaccination strategies are needed to combat tularemia. Here we discuss the current state of and challenges to the tularemia vaccine field and suggest novel vaccine approaches going forward that might be better suited for protecting against F. tularensis infection.

Establishment of isotype-switched, antigen-specific B cells in multiple mucosal tissues using non-mucosal immunization

Although most pathogens infect the human body via mucosal surfaces, very few injectable vaccines can specifically target immune cells to these tissues where their effector functions would be most desirable. We have previously shown that certain adjuvants can program vaccine-specific helper T cells to migrate to the gut, even when the vaccine is delivered non-mucosally. It is not known whether this is true for antigen-specific B cell responses. Here we show that a single intradermal vaccination with the adjuvant double mutant heat-labile toxin (dmLT) induces a robust endogenous, vaccine-specific, isotype-switched B cell response. When the vaccine was intradermally boosted, we detected non-circulating vaccine-specific B cell responses in the lamina propria of the large intestines, Peyer's patches, and lungs. When compared to the TLR9 ligand adjuvant CpG, only dmLT was able to drive the establishment of isotype-switched resident B cells in these mucosal tissues, even when the dmLT-adjuvanted vaccine was administered non-mucosally. Further, we found that the transcription factor Batf3 was important for the full germinal center reaction, isotype switching, and Peyer's patch migration of these B cells. Collectively, these data indicate that specific adjuvants can promote mucosal homing and the establishment of activated, antigen-specific B cells in mucosal tissues, even when these adjuvants are delivered by a non-mucosal route. These findings could fundamentally change the way future vaccines are formulated and delivered.

Cross-Reactive Antibodies to SARS-CoV-2 and MERS-CoV in Pre-COVID-19 Blood Samples from Sierra Leoneans

Many countries in sub-Saharan Africa have experienced lower COVID-19 caseloads and fewer deaths than countries in other regions worldwide. Under-reporting of cases and a younger population could partly account for these differences, but pre-existing immunity to coronaviruses is another potential factor. Blood samples from Sierra Leonean Lassa fever and Ebola survivors and their contacts collected before the first reported COVID-19 cases were assessed using enzyme-linked immunosorbent assays for the presence of antibodies binding to proteins of coronaviruses that infect humans. Results were compared to COVID-19 subjects and healthy blood donors from the United States. Prior to the pandemic, Sierra Leoneans had more frequent exposures than Americans to coronaviruses with epitopes that cross-react with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), SARS-CoV, and Middle Eastern respiratory syndrome coronavirus (MERS-CoV). The percentage of Sierra Leoneans with antibodies reacting to seasonal coronaviruses was also higher than for American blood donors. Serological responses to coronaviruses by Sierra Leoneans did not differ by age or sex. Approximately a quarter of Sierra Leonian pre-pandemic blood samples had neutralizing antibodies against SARS-CoV-2 pseudovirus, while about a third neutralized MERS-CoV pseudovirus. Prior exposures to coronaviruses that induce cross-protective immunity may contribute to reduced COVID-19 cases and deaths in Sierra Leone.

Salmonella Biofilm Formation, Chronic Infection, and Immunity Within the Intestine and Hepatobiliary Tract

Within the species of Salmonella enterica, there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many Salmonella species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of Salmonella, the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of Salmonella (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Salmonella Typhi, Salmonella Typhimurium, and invasive non-typhoidal Salmonella that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to Salmonella in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of Salmonella immunity, particularly as it relates to chronic infection.

Blade and balloon atrial septostomy for left heart decompression in patients with severe ventricular dysfunction on extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is used as circulatory support or bridge to transplantation in patients with severe left ventricular (LV) dysfunction. Left heart decompression is needed to reduce pulmonary edema, prevent pulmonary hemorrhage, and reduce ventricular distention that may aid in recovery of function. We reviewed our experience from November 1993 to December 1997 with 10 patients having severe LV dysfunction (7 myocarditis, 3 dilated cardiomyopathy) who required circulatory support with ECMO and who underwent left heart decompression with blade and balloon atrial septostomy (BBAS). Patients ranged in age from 1 to 24 years (median, 3 years). Indications for BBAS included left atrial/left ventricular distension (10), pulmonary edema/hemorrhage (9), or severe mitral regurgitation (2). BBAS was performed electively in eight patients and urgently in two patients. BBAS was performed while on ECMO in seven patients and pre-ECMO in three. A femoral venous approach was used in all patients. ECMO patients were fully heparinized. Transseptal puncture was required in nine patients while one patient had a patent foramen ovale. Blade septostomy was performed in all patients. Enlargement of the defect was then performed by stationary balloon dilation in nine and Rashkind balloon atrial septostomy in one. Balloon diameters ranged from 10 to 20 mm. Sequential balloon inflations were performed in some patients. Adequacy of the atrial septal defect (ASD) was confirmed by pressure measurement and echocardiography. Adequate left heart decompression was achieved in all patients. Pulmonary edema improved in nine of nine patients. Left atrial mean pressure fell from a mean of 30.5 mm Hg, (range, 12-50 mm Hg) to 16 mm Hg (range, 9-24 mm Hg). Left atrial to right atrial pressure gradient fell from a mean of 20 mm Hg pre-BBAS to 3 mm Hg post-BBAS. ASDs ranged in size from 2.5 to 8 mm (mean, 5.9 mm). Complications included needle perforation of the left atrium without hemodynamic compromise (one), ventricular fibrillation requiring defibrillation (one), and hypotension following BBAS which responded to volume infusion (two). Duration of ECMO ranged from 41 hr to 704 hr (mean, 294 hr). Seven patients survived and four patients had recovery of normal LV function. Of those who recovered, two had no ASD at follow-up while two ASDs are patent 14 days and 3 months post-BBAS. Three patients underwent successful cardiac transplantation. Three patients died, all of whom had multisystem organ failure with or without sepsis. A patent ASD was noted at transplant (three) or autopsy (two). No patient required a second BBAS. BBAS alleviates severe left atrial hypertension and pulmonary edema. In addition, BBAS avoids the potential bleeding complications of surgical left heart decompression. Stationary balloon dilation of the atrial septum is an effective alternative to Rashkind balloon septostomy in older patients. BBAS achieves left heart decompression that may permit recovery of LV function or allow extended ECMO support as a bridge to transplant.

Prolonged extracorporeal life support for bridging to transplant: technical and mechanical considerations

Through July 1995, the Extracorporeal Life Support Organization (ELSO) registry listed 87 patients who received extracorporeal life support (ECLS) as a bridge to cardiac transplantation with a survival rate of 41%. At Arkansas Children's Hospital, 17 patients (aged between two days and 24 years) with diagnoses of dilated cardiomyopathy (seven), postcardiotomy (seven) and acute viral myocarditis (three) were bridged with ECLS. Mechanical complications only occurred in two patients, neither of which necessitated withdrawal of ECLS. Decompression of the left heart was performed in 11 patients, six via a surgically placed vent and five with a blade/balloon artial septostomy. Documented infection occurred in 11/17 patients, but only one patient died from infection. Fifteen of 17 patients (88%) recovered or were transplanted, of which 13 (76%) were discharged home. With left-heart decompression and appropriate treatment of infection, ECLS may be used as a bridge to cardiac transplantation or until the return of cardiac function.

Extracorporeal life support of neonates with congenital cardiac defects: techniques used during cardiac catheterization and surgery

Neonatal patients with congenital cardiac defects require proper diagnosis often by cardiac catheterization before surgical repair. In our institution, patients whose echocardiograms reveal surgically correctable lesions, but who are severely decompensated, have been placed on Extracorporeal Life Support (ECLS) prior to catheterization or surgery. Subsequent management of ECLS and cardiopulmonary bypass (CPB) are dictated by the surgical procedure. Hypothermia can be utilized while on ECLS to facilitate low-flow CPB, or circulatory arrest. Total extracorporeal circulation may be performed with the ECLS circuit, or the patient may be transferred to a conventional CPB circuit during the procedure. If required, post surgical ECLS can be facilitated through prior cannulation. We have found pre-operative institution of ECLS, in the neonate with severe congenital cardiac defects, provides immediate control of hemodynamic and respiratory problems, lowers the risk of cardiac catheterization, and reduces the usage of blood products during surgery.

Thromboembolism in patients undergoing thoracotomy

To determine the incidence of thromboembolism in relation to thoracotomy, 77 patients undergoing pulmonary resection were prospectively studied up to 30 days postoperatively for deep venous thrombosis and pulmonary embolism. Overall, 20 of 77 patients (26%) had thromboembolic events during their hospitalization. Four deep venous thromboses and 1 pulmonary embolism were detected in 5 of 77 patients preoperatively for an incidence of 6%. Postoperative thromboembolism was detected in 15 of 77 (19%): deep venous thrombosis in 11 (14%) and pulmonary embolism in 4 (5%). No postoperative thromboembolisms occurred in the 17 patients receiving preoperative aspirin or ibuprofen, whereas they did occur in 25% of the remainder (15/60). Thromboembolism after pulmonary resection was more frequent with bronchogenic carcinoma than with metastatic cancer or benign disease (15/59 [25%] versus 0/18 [0%]; p < 0.01), adenocarcinoma compared with other types of carcinoma (11/25 [44%] versus 4/34 [12%]; p < 0.0004), large primary lung cancer (> 3 cm in diameter) compared with smaller lesions (9/19 [47%] versus 6/40 [15%]; p < 0.0001), stage II compared with stage I (7/14 [50%] versus 7/34 [21%]; p < 0.04), and pneumonectomy or lobectomy compared with segmentectomy and wedge resection (14/49 [29%] versus 1/28 [4%]; p < 0.005). Three of 4 patients with thromboembolism detected preoperatively had operation within the previous year. Postoperative pulmonary embolism was fatal in 1 of 4 (25%) and accounted for the one death. These results suggest patients undergoing thoracotomy for lung cancer, especially adenocarcinoma, should be considered for thromboembolic prophylaxis.

Mobile extracorporeal membrane oxygenation

Transport of critically ill neonates in need of extracorporeal membrane oxygenation can be risky. Their extreme cardiorespiratory instability may delay or even preclude conventional transport to an extracorporeal membrane oxygenation center. We report the use of a UH-1 helicopter specially adapted for mobile extracorporeal membrane oxygenation support to transport a critically ill neonate.

Extracorporeal membrane oxygenation for cardiac failure after congenital heart operation

Despite continuing improvement in myocardial protection and surgical technique, the repair of complex congenital heart lesions can result in cardiopulmonary compromise refractory to conventional therapy. In a 29-month period, 24 patients (aged 14 hours to 6 years) were treated with extracorporeal membrane oxygenation (ECMO) 28 times for profound cardiopulmonary failure. Four patients required ECMO after each of two cardiopulmonary bypass procedures. Seventeen patients required ECMO to be initiated in the operating room: 12 (71%) were weaned successfully from ECMO, and 8 (47%) survived. Seven patients had ECMO initiated in the intensive care unit: 6 (86%) were weaned, and 5 (71%) survived. Serial echocardiograms demonstrated substantial recovery of cardiac function in 18 of 21 instances (86%) of ventricular failure from myocardial dysfunction. Overall, 18 of 24 patients (75%) were successfully weaned from ECMO including all 4 who underwent 2 ECMO treatments. We conclude that ECMO can successfully salvage children who have serious cardiopulmonary failure immediately after a congenital heart operation and that long-term survival is possible after two ECMO treatments.

Evaluation of the reconstructed carotid artery following extracorporeal membrane oxygenation

Over a 12-month period, 28 neonatal patients in respiratory failure were supported with extracorporeal membrane oxygenation (ECMO), and 11 of these underwent successful repair of the right carotid artery post-ECMO. Nine of 11 were studied with duplex color-flow Doppler imaging between 14 and 109 days of age and again at 1 year of age. A velocity ratio (A/B) of the peak systolic velocity above the level of the anastomosis to the peak systolic velocity below the anastomosis was measured to assess the degree of stenosis, if any, at the repair site. Antegrade flow through the carotid was detected post-ECMO in 8 of 9 infants, and antegrade and retrograde flow was documented in 1 infant. A/B ratios ranged from 1.00 to 8.60 (A/B ratio of 1 is normal; 2.0 indicates at least a 50% obstruction to flow). Four of 9 patients had ratios greater than 2.0, and 8 of 9 exhibited some evidence of obstruction. Follow-up scans were performed on 8 of 9 infants between 12 and 18 months of age. All infants examined showed marked improvement in A/B ratio and patency of the vessel, documenting that initial narrowing of the vessel is reversible. No infant had evidence of embolic phenomena to the right side of the brain by magnetic resonance imaging. Repair of the common carotid artery post-ECMO is technically feasible without increasing the risk of brain injury.

Omental pedicle grafting in the treatment of postcardiotomy sternotomy infection

Postcardiotomy sternal infection occurred in 20 (2%) of 1007 patients undergoing cardiac surgery between September 1985 and December 1987, a 10-fold increase over the preceding 33 months (4 [0.24%] of 1627 patients). Cultures were sterile in 5 patients and yielded staphylococci in 12 and a variety of bowel organisms in 3. The cause for the increased occurrence of sternal wound infection is unclear after multivariate analysis, although infections have precipitously dropped subsequent to changing to cefuroxime sodium antibiotic prophylaxis. Treatment has evolved to appropriate antibiotics and early débridement of involved sternum and cartilage. Rewiring the sternum is not attempted. If gross purulence is not present, primary closure is accomplished using muscle flaps (2 patients) or omental pedicle grafts (17 patients). In the presence of gross purulence, the wound is packed open for 5 days and then closed in the above fashion. Two patients required skin grafts for primary closure. The omental pedicle flap is preferred due to simplicity and improved coverage of the sternal defect inferiorly. Nineteen patients healed primarily. A superficial wound infection was drained in 1 patient. Midline incisional hernias developed in 3 muscular patients. Omentum is now harvested through a left subcostal incision. Hospital stay was under 2 weeks in 13 patients. One death occurred due to multisystem failure prior to completion of wound closure. In our experience, early sternal débridement and omental pedicle grafting with primary closure is appropriate therapy for postcardiotomy sternotomy infections. The presence of gross purulence may require 5 days of open packing prior to omental grafting. No significant complications occurred, and mortality was low. A left subcostal incision for omental harvesting is utilized to avoid the occurrence of delayed incisional hernias.

Internal banding for palliation of truncus arteriosus in the neonate

A method for surgically limiting pulmonary blood flow in the critically ill neonate with truncus arteriosus is described. Two recent cases utilizing this technique are presented. Comparisons are made between this and other palliative surgical procedures used in truncus arteriosus.

Effect of nuclear magnetic resonance on chromosomes of mouse bone marrow cells

Three groups of six male Balb/c mice, subjected to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 K Gauss for one hour, were each compared to another group of ten unexposed mice with respect to chromatid and chromosomal aberrations. The exposed groups were sacrificed at two hours, 24 hours and 48 hours following NMR exposure respectively. Control mice were sacrificed 24 hours after sham-exposure. All groups had approximately 0.02 apparent aberrations per cell. These apparent aberrations were in the form of metacentric chromosomes, possibly resulting from a union of chromosomes at their centromeres or possibly simply chromosomes in association. The results are consistent with earlier in vitro findings that NMR exposure causes no adverse cytogenetic effects.

Development and evaluation of pulsatile roller pump and tubing for cardiac assistance

In our laboratories we have developed a roller pump for cardiopulmonary bypass and circulatory assistance that has the ability to produce steady or pulsatile flow. The pulsatile mode can also be used for counterpulsation. The roller pump has been tested both experimentally and clinically. Studies have also been performed in vitro and in vivo to evaluate and select the best medical-grade roller pump tubing to be used in the pump for short- and long-term support. In vitro tests included rebounding of tubing volume versus revolutions per minute, rebounding over time with continuous pumping, flex life, and spallation. In vivo testing was performed in mongrel dogs using heparinless left heart bypass pumping for 6 h. Hematologic studies were performed during the procedure. Postmortem examination was performed, looking especially for thromboembolism. The tubing and connectors were also inspected. The results of the in vivo and in vitro tests of all tubings were then compared.

Effect of dimethyl sulfoxide on hematopoietic stem cells in mice

The effects of dimethyl sulfoxide (DMSO) were studied in irradiated BALB/c mice to see if DMSO has a stimulatory effect on hematopoietic stem cells. The spleen colony forming technique was employed. DMSO given after a lethal dose of radiation enhanced post-irradiation recovery and survival. The erythroid to granuloid spleen colony ratio was higher in the DMSO treated group compared to the controls. There was some evidence of an increase in the endogenous formation of erythroid colonies after DMSO treatment (0.38%). However, DMSO had no effect on exogenous erythroid colony formation; rather, it inhibited granuloid differentiation.

Lymphocyte replication in lung cancer patients undergoing radiotherapy

In vivo and in vitro survival and response of lymphocytes were studied in 12 lung cancer patients before, during and following radiotherapy, and comparisons were made to data from 20 healthy control subjects. Lymphocyte counts of lung cancer patients prior to radiotherapy did not differ significantly from those of control subjects. Following radiotherapy, lymphocyte counts were significantly reduced. The in vitro survival of lymphocytes from lung cancer patients prior to radiotherapy was lower than that of normal controls. Radiation treatment had no effect on lymphocyte survival in vitro. PHA-stimulated lymphoblast formation in lung cancer patients prior to radiotherapy did not differ from that of normal controls, but decreased significantly during radiotherapy.

Aryl hydrocarbon hydroxylase inducibility in lung cancer patients undergoing radiotherapy

Aryl hydrocarbon hydroxylase (AHH) inducibility was studied in cultured lymphocytes from 21 healthy control subjects and from 15 lung cancer patients selected for radiation therapy. AHH inducibility of the patients was measured prior to, during and at the end of radiation therapy. Four of 15 patients had values comparable to the healthy controls. Cellular DNA and protein measurements of cultured lymphocytes were the same for patients and healthy controls. There was no significant difference in the percentage of lymphoblast formation and percentage of cell survival between the two groups. Radiation therapy reduces the number of lymphocytes in vivo and the amount of lymphoblast formation in vitro. AHH inducibulity is signifcantly lowered by radiation in the patients who had very high inducibility at pre-treatment level. DNA and protein contents of cultured lymphocytes did not change during radiation therapy.

Aryl hydrocarbon hydroxylase inducibility and lymphoblast formation in lung cancer patients

Aryl hydrocarbon hydroxylase (AHH) inducibility and lymphoblast formation were studied in lymphocytes from healthy control subjects and from lung cancer patients undergoing radiotherapy. The relationship between AHH inducibility and percentage lymphoblasts was statistically significant only for the pre-treatment patients (r = 0.598; p less than 0.05). In the control group and in patients undergoing radiotherapy the correlation between AHH inducibility and lymphoblast formation was positive but statistically it was not significant. Our data do not suggest a linear relationship between AHH inducibility and lymphoblast formation.

Cerebellopontine angle tumor: diagnosis by oblique projection vertebral angiography

Oblique projection vertebral angiography is the simplest and most accurate angiographic method of detecting small cerebellopontine angle tumors. The vascular blood supply to the tumor and brainstem is displayed as the surgeon will encounter it during lateral suboccipital craniotomy. The procedure is comfortable for the patient, technically easy to perform, and reproducible. Interpretation is relatively unaffected by variations in vascular anatomy or superimposed vessel or bone images. This method can be used to supplement routine views, or be performed alone with stereoscopic filming.

Induction of hepatic aryl hydrocarbon hydroxylase in C57BL mice by ionizing radiation

Inbred strains of C57BL mice were exposed to either 100, 500, or 1000 rads of whole-body irradiation. Another group of mice were given injections of 3-methylcholanthrene only, and a control group had no treatment. Forty-eight hr after treatment, the animals were killed and hepatic aryl hydrocarbon hydroxylase (AHH) activity was measured by spectrophotofluorometer. A comparison of hepatic AHH activity in treated and nontreated groups of mice showed that each treated group had a significantly increased AHH induction compared with the control group. Although radiation appeared to have a dose-related effect on AHH induction, the increase with dose level was not statistically significant.

Juvenile nasopharyngeal angiofibroma: radiographic aspects

Because of consistent and unique radiographic features of JNA, it is not necessary, nor is it advisable, to biopsy these tumors to establish a diagnosis. In addition, the carotid arteriograms show the major feeding vessels to the lesion and also completely delineate the periphery of the tumor, thus establishing operability versus non-operability. If a JNA is treated by radiotherapy, the changes effected can be followed by carotid arteriography.