Treatment delay from onset of occipital neuralgia symptoms to treatment with nerve decompression surgery: a prospective cohort study

BACKGROUND

The aims of this study were to (1) evaluate the time between onset of occipital neuralgia symptoms and nerve decompression surgery, (2) perform a cost comparison analysis between surgical and nonsurgical treatment of occipital neuralgia, and (3) report postoperative results of nerve decompression for occipital neuralgia.

METHODS

Subjects (n = 1112) who underwent screening for nerve decompression surgery were evaluated for occipital neuralgia. Of those, 367 patients (33%) met the inclusion criteria. Timing of occipital neuralgia symptom onset and pain characteristics were prospectively collected. Cost associated with the nonsurgical treatment of occipital neuralgia was calculated for the period between onset of symptoms and surgery.

RESULTS

A total of 226 patients (73%) underwent occipital nerve decompression. The average time between onset of occipital neuralgia and surgery was 19 years (7.1-32). Postoperatively, the median number of pain days per month decreased by 17 (0-26, 57%) (P < .001), the median pain intensity decreased by 4 (2-8, 44%) (P < .001), and median pain duration in hours was reduced by 12 (2-23, 50%) (P < .001). The annual mean cost of nonsurgical occipital neuralgia treatment was $28 728.82 ($16 419.42-$41 198.41) per patient. The mean cost during the 19-year time frame before surgery was $545 847.75($311 968.90-$782 769.82).

CONCLUSION

This study demonstrates that patients suffer from occipital neuralgia for an average of 19 years before undergoing surgery. Nerve decompression reduces symptom severity significantly and should be considered earlier in the treatment course of occipital neuralgia that is refractory to conservative treatment to prevent patient morbidity and decrease direct and indirect health care costs.

Gabapentin for Postoperative Pain Control and Opioid Reduction in Scrotal Surgery: A Randomized Controlled Clinical Trial

PURPOSE

To assess the safety and efficacy of gabapentin in reducing postoperative pain among patients undergoing scrotal surgery for male infertility by conducting a randomized, double-blind, placebo-controlled trial.

MATERIALS AND METHODS

In this randomized, double-blind, placebo-controlled trial, healthy men undergoing scrotal surgery with a single surgeon were randomized to receive either (1) gabapentin 600 mg given 2 hours preoperatively and 300 mg taken 3 times a day postoperatively for 3 days, or (2) inactive placebo. The primary outcome measure was difference in postoperative pain scores. Secondary outcomes included differences in opioid usage, patient satisfaction, and adverse events.

RESULTS

Of 97 patients screened, 74 enrolled and underwent randomization. Of these, 4 men were lost to follow-up, and 70 were included in the final analysis (35 gabapentin, 35 placebo). Both differences in initial postoperative mean pain score (-1.14, 95% CI -2.21 to -0.08, P = .035) and final mean pain score differences (-1.27, 95% CI -2.23 to -0.32, P = .0097) indicated lower gabapentin pain compared to placebo. There were no statistically significant differences in opioid usage, patient satisfaction, or adverse events.

CONCLUSIONS

These data suggest that perioperative gabapentin results in a statistically and clinically significant decrease in pain following scrotal surgery. While there was no evidence of an impact on opioid usage or patient satisfaction, given the low risk of adverse events, it may be considered as part of a multimodal pain management strategy.

What Is Medical Extended Reality? A Taxonomy Defining the Current Breadth and Depth of an Evolving Field

Medical extended reality (MXR) has emerged as a dynamic field at the intersection of health care and immersive technology, encompassing virtual, augmented, and mixed reality applications across a wide range of medical disciplines. Despite its rapid growth and recognition by regulatory bodies, the field lacks a standardized taxonomy to categorize its diverse research and applications. This American Medical Extended Reality Association guideline, authored by the editorial board of the Journal of Medical Extended Reality, introduces a comprehensive taxonomy for MXR, developed through a multidisciplinary and international collaboration of experts. The guideline seeks to standardize terminology, categorize existing work, and provide a structured framework for future research and development in MXR. An international and multidisciplinary panel of experts was convened, selected based on publication track record, contributions to MXR, and other objective measures. Through an iterative process, the panel identified primary and secondary topics in MXR. These topics were refined over several rounds of review, leading to the final taxonomy. The taxonomy comprises 13 primary topics that jointly expand into 180 secondary topics, demonstrating the field's breadth and depth. At the core of the taxonomy are five overarching domains: (1) technological integration and innovation; (2) design, development, and deployment; (3) clinical and therapeutic applications; (4) education, training, and communication; and (5) ethical, regulatory, and socioeconomic considerations. The developed taxonomy offers a framework for categorizing the diverse research and applications within MXR. It may serve as a foundational tool for researchers, clinicians, funders, academic publishers, and regulators, facilitating clearer communication and categorization in this rapidly evolving field. As MXR continues to grow, this taxonomy will be instrumental in guiding its development and ensuring a cohesive understanding of its multifaceted nature.

Dishonest Physician Reviews: Challenging Physician Online Reviews and the Appeals Process

Physician reviews influence how patients seek care, but dishonest reviews can be detrimental to a physician practice. It is unclear if reviews can be challenged, and processes differ and are not readily apparent. The objective of this observational study was to determine the ability to challenge dishonest negative reviews online. Commonly used websites for physician reviews as of August 2021 were utilized: Healthgrades, Vitals, RateMDs, Zocdoc, Yelp, and Google Business. Each review platform's website was tested for leaving a physician review and process of appeal and possible removal of a negative review. The process for appeal and the steps involved in posting and appealing a review were determined, whether individuals are verified patients and criteria for verification, how physicians can respond, and the process of appealing false or defamatory reviews.Any individual can leave reviews by searching for a physician's name or practice and visiting their profile page and can then provide a rating and written review of their experience with the physician. Many require verification to prevent suspicious activity but not proof of a medical visit, allowing significant potential for inaccurate review postings. Posting a review can be done by anyone without verification of a visit. It is challenging for physicians to remove negative online reviews, as most review platforms have strict policies against. This review concludes that physicians should be aware of their online presence and the steps that can be taken to address issues to mitigate adverse effects on their practices.

Preliminary effects of low-intensity focused ultrasound treatment program for cancer-related neuropathic pain

Aim: To evaluate the effectiveness of low-intensity focused ultrasound (LIFU) therapy in the management of cancer-related neuropathic pain (CNP). Methods: A retrospective review with 22 patients with CNP treated with LIFU therapy (frequency 3 Hz, 3 W/cm², pulse mode duty cycle 50%) was conducted. Results: Out of the 22 patients, 15 had CNP secondary to chemotherapy-induced peripheral neuropathy. Compared with baseline, there was a significant reduction in numeric pain rating scale (p < 0.001). Additionally, 76.5% of patients (n = 13) were considered to be responders to LIFU therapy. Conclusion: LIFU therapy may be a viable treatment modality in the management of CNP, specifically chemotherapy-induced peripheral neuropathy, with a minimal side effect profile. Larger, prospective studies with a structured protocol are necessary.

Cannabis, anesthesia and acute postoperative pain: known and unknown

Tweetable abstract Cannabis use may significantly affect anesthetic, perioperative and acute pain management care; but research needs to be standardized, expanded and more inclusive.

Failure of SCS MR-Conditional Modes Due to High Impedance: A Review of Literature and Case Series

Introduction

Magnetic resonance imaging (MRI) conditional modes are a novel feature for certain Food and Drug Administration (FDA)-approved spinal cord stimulation (SCS) devices. However, there is a paucity of literature around the limitation of MRI-conditional modes (“MRI safe”), specifically in clinical scenarios where urgent MRIs may be needed. One such limitation is load impedance, referring to the circuit’s resistance to the current being generated by the system. High impedance can limit the MRI-conditional mode capability, presenting potential harm to a patient undergoing an MRI or make an MRI unable to be completed.

Methods

Three cases were identified, and informed consent was obtained. All information was obtained via retrospective chart review.

Results

In this case series of three patients where MRI-conditional SCS systems were unable to be placed in “MRI safe” settings, preventing timely MRI study completion in the setting of high impedance, all three were required to undergo alternative imaging including CT scans, and two patients ultimately had the system explanted and one chose to be re-implanted after completion of scans.

Conclusion

This case series highlights the need for further investigation of impedance in SCS systems and potential limitations for future MRI usage. The review of literature of impedance in SCS shows both device- and physiologic-related etiologies for changes in impedance that warrant consideration by the implanting physician.

Neuromodulation and the Epidemiology of Magnetic Resonance Utilization for Lung, Breast, Colon, and Prostate Cancer

BACKGROUND

Neuromodulation is a growing therapeutic modality for the treatment of chronic pain. Determining whether a patient is an appropriate candidate for implantation of a neuromodulatory device and whether the device requires an MRI conditional feature necessitates understanding the patient's likelihood of requiring an MRI. Active treatment of cancer represents known high-risk clinical scenarios for MRI. However, the growth of MRI as a tool for diagnosis of cancer also warrants consideration by implanting physicians when assessing high-risk patients.

MATERIALS AND METHODS

Here, we conduct a systematic review of the literature to determine the epidemiology for MR utilization for breast, lung, prostate, and colon cancer. Out of 126 papers reviewed, 39 were ultimately analyzed to determine the relative likelihood of an MRI in the course of oncologic care.

RESULTS

We find that there is a low likelihood for MRI to be utilized as part of any screening process and a variable likelihood during the staging and surveillance phases across all cancer subtypes depending on the clinical circumstances. Certain populations present special consideration for MRI screening, such as the high at-risk breast cancer population, and MRI surveillance and staging, such as aging males (>50 years old) at risk for prostate cancer or individuals diagnosed with rectal cancers.

CONCLUSION

High likelihood of MRI within the oncologic context represents important distinction criteria for neuromodulation as patients may benefit from implantation of an MR conditional system.

No protocol and no liability: a call for COVID crisis guidelines that protect vulnerable populations

The COVID-19 pandemic is revealing the unacceptable health disparities across New York City and in this country. The mortality rates of vulnerable and minority populations alone suggest a need to re-evaluate clinical decision making protocols, especially given the recently passed Emergency or Disaster Treatment Protection Act, which grants healthcare institutions full immunity from liability stemming from resource allocation/triage decisions. Here we examine the disparity literature against resource allocation guidelines, contending that these guidelines may propagate allocation of resources along ableist, ageist and racial biases. Finally, we make the claim that the state must successfully develop ones that ensure the just treatment of our most vulnerable.

Postoperative hemiparesis due to conversion disorder after moderate sedation: a case report

Peri-operative conversion disorder that manifests as postoperative muscle weakness is an uncommon diagnosis made through exclusion of neurological, metabolic or iatrogenic aetiologies. We present a case where a patient with a considerable history of physical and psychological trauma suffered from prolonged right-sided hemiparesis following a breast biopsy under moderate-to-deep sedation. Conversion disorder following moderate-to-deep sedation has yet to be discussed in the literature, as all previous cases have described postoperative conversion disorder in the setting of general or central neuraxial anaesthesia. Our recommendation is for practitioners to keep conversion disorder on the list of differential diagnoses, despite the depth of sedation or type of anaesthetic utilised, and perform the same detailed neurological, metabolic and psychiatric assessment when considering postoperative weakness.

Increase in HIV Receptors/Co-receptors/α-defensins in Inflamed Human Gingiva

Transmission of HIV-1 through the oral cavity is considered to be a rare event. To identify factors in resistance/susceptibility to oral HIV-1 infection, we analyzed expression in human gingiva of HIV-1 receptors Langerin, DC-SIGN, MR, and GalCer, HIV-1 co-receptors CCCR5, CXCR4, and anti-microbial protein α-defensin-1. Our results show that healthy gingiva is infiltrated with cells expressing all HIV-1 receptors tested; however, there are very few CCR5+ cells and a complete absence of CXCR4+ cells in the lamina propria. In chronic periodontitis (CP), DC-SIGN, MR, CXCR4, and CCR5 increase, but this was accompanied by a ten-fold increase in α-defensin-1 mRNA. The CCR5+ cells were revealed to be T-cells, macrophages, and dermal dendritic cells. Moreover, epithelial expression of GalCer and CXCR4 together was not apical and showed no trend with underlying inflammation. Thus, low expression of HIV-1 co-receptors in health and high expression of α-defensin during CP may comprise endogenous factors that provide protection from oral HIV-1 infection.

Differential capacity for complement receptor-mediated immune evasion by Porphyromonas gingivalis depending on the type of innate leukocyte

The complement system plays a central role in immunity and inflammation, although certain pathogens can exploit complement to undermine protective immunity. In this context, the periodontal keystone pathogen Porphyromonas gingivalis was previously shown by our group to evade killing by neutrophils or macrophages through exploitation of complement C5a receptor 1 (C5aR1) and complement receptor 3 (CR3). Here, we examined whether P. gingivalis uses complement receptors to also subvert killing by dendritic cells. In line with earlier independent studies, intracellular viable P. gingivalis bacteria could be recovered from mouse bone-marrow-derived dendritic cells (BMDC) or human monocyte-derived dendritic cells (MDDC) exposed to the pathogen. However, in the presence of C5a, the intracellular survival of P. gingivalis was significantly decreased in a C5aR1-dependent way. Further work using wild-type and receptor-knockout BMDC showed that, in the presence of C3a, the C3a receptor (C3aR) similarly enhanced the intracellular killing of P. gingivalis. In contrast, C5aR2, an alternative receptor for C5a (G protein-coupled receptor 77), was associated with increased intracellular P. gingivalis viable counts, consistent with the notion that C5aR2 functions as a negative regulator of C5aR1 activity. Moreover, P. gingivalis failed to use CR3 as a phagocytic receptor in BMDC, in contrast to our earlier findings in macrophages where CR3-mediated uptake promotes P. gingivalis survival. Collectively, these data show that complement receptors mediate cell-type-specific effects on how innate leukocytes handle P. gingivalis, which appears to exploit complement to preferentially evade those cells (neutrophils and macrophages) that are most often encountered in its predominant niche, the periodontal pocket.

Shaken but prepared: Analysis of disaster response at an academic medical centre following the Boston Marathon bombings

Over the last decade, there has been a rise in the number of mass casualty incidences (MCIs) and their subsequent effect on hospital systems. While there has been much discussion over improving procedures to treat victims of MCIs, there has not been a thorough, systems-based analysis concerning the costs incurred by hospitals during such events. Here the authors examine the history of the Hospital Incident Command Center and how its evolution at Tufts Medical Center helped mitigate the damage following the Boston Marathon Bombings. Tufts' unique variations to the Hospital Incident Command Center include strategic communication hierarchies and a 'zero cost centre' financial system which both provided for a quick and adaptive response. Operating in collaboration with the Conference of Boston Teaching Hospitals encouraged coordination and preparation during emergency situations such as mass casualty events. The direct and indirect effects on Tufts Medical Center stemming from the Boston Marathon Bombings were analysed. Tufts MC treated 36 victims immediately following the MCI. The estimated total cost during the week of April 15 to April 19, 2013 was $776,051. The cost was primarily comprised of lost revenue from cancelled outpatient and inpatient hospital services, as well as expenses incurred due to overtime pay, salary expenses, PPE kits and hospitality services. Finally, the authors examine ways to reduce the future costs during emergency situations through increasing communication with employees, understanding the source of all direct expenses, and mitigating excess risk by developing partnerships with other hospital systems.

Dendritic cells at the oral mucosal interface

The mucosal lining of the respiratory and digestive systems contains the largest and most complex immune system in the body, but surprisingly little is known of the immune system that serves the oral mucosa. This review focuses on dendritic cells, particularly powerful arbiters of immunity, in response to antigens of microbial or tumor origin, but also of tolerance to self-antigens and commensal microbes. Although first discovered in 1868, the epidermal dendritic Langerhans cells remained enigmatic for over a century, until they were identified as the most peripheral outpost of the immune system. Investigators' ability to isolate, enrich, and culture dendritic cells has led to an explosion in the field. Presented herein is a review of dendritic cell history, ontogeny, function, and phenotype, and the role of different dendritic cell subsets in the oral mucosa and its diseases. Particular emphasis is placed on the mechanisms of recognition and capture of microbes by dendritic cells. Also emphasized is how dendritic cells may regulate immunity/tolerance in response to oral microbes.

Oral mucosal expression of HIV-1 receptors, co-receptors, and alpha-defensins: tableau of resistance or susceptibility to HIV infection?

The basic premise of whether transmission of HIV-1 through the oral mucosa actually occurs, and through what route, is a topic of intense interest. Our work has focused on HIV-1 receptors/co-receptors and alpha-defensin-1 in situ in human gingiva. Regardless of HIV-1 infection, the role that C-type lectin receptors might play in periodontal pathogenesis is of great interest. We have shown that the gingival lamina propria, when inflamed, becomes increasingly infiltrated with DC-SIGN+MR+ dermal dendritic cells (DDCs), while the inflamed epithelium shows a decrease in Langerin+ Langerhans cells (LCs). Moreover, DDCs and LCs contribute to the mature CD83+ DC pool in situ, and form immune conjugates with CD4+ T-cells in the lamina propria (Jotwani and Cutler, 2003). This raises the intriguing possibility that oral mucosal DCs may be involved in HIV-1 transfer to T-cells in situ. However, this possibility is tendered by the challenges faced by the virus in gaining access to oral mucosal immune cells, including their ability to survive the salivary defenses, cross the mucosal barrier, resist inactivation by alpha-defensins, and overcome the paucity of co-receptor CCR5 in (healthy) oral mucosa (i.e., required for productive infection [Jotwani et al., 2004]). To date, there is little evidence of direct infection by HIV-1 of oral mucosal DCs/T cells and other cells in situ. Abbreviations used in this paper: CP, chronic periodontitis; CCR5, chemokine receptor 5; CXCR4, C-X-C receptor 4; DCs, dendritic cells; DC-SIGN, DC-specific ICAM-3 grabbing non-integrin; DDC, dermal dendritic cells; LCs, Langerhans cells; LP, lamina propria; MR, mannose receptor.

Multiple dendritic cell (DC) subpopulations in human gingiva and association of mature DCs with CD4+ T-cells in situ

Gingival epithelium is a site of active trafficking of Langerhans cells (LCs), while the lamina propria in chronic periodontitis (CP) contains CD83+ mature dendritic cells (mDCs) and CD4+ T-cells. The immune cells that contribute to the mDCs, and whether mDCs engage with T-cells in situ, are unclear. Using several immunohistochemical approaches, combined with fluorescence-, light-, and scanning laser confocal-microscopy, we show that, in addition to LCs, the gingiva contains dermal DCs (DDCs) in the lamina propria; moreover, DDCs increase in number during CP. Furthermore, DDCs, LCs, and B-cells co-express CD83 in CP and contribute to the mDC pool. Double-staining for CD83 and CD4 revealed that mDCs associate with clusters of CD4+ T-cells in the lamina propria. Analysis of these data suggests that multiple DC subsets mature in the gingiva and that mature DCs engage in antigen presentation with T-cells in chronic periodontitis.

Association between periodontitis and hyperlipidemia: cause or effect?

BACKGROUND

Epidemiological studies suggest a relationship between periodontitis and coronary artery disease, but the mechanism has not been established. Recent studies in animals indicate that low dose endotoxin, as in a gram-negative infection, can induce hyperlipidemia and myeloid cell hyperactivity. The association between periodontitis, systemic exposure to Porphyromonas gingivalis, lipopolysaccharides (LPS), and hyperlipidemia has not been examined in humans.

METHODS

Sera were obtained from 26 adult periodontitis patients and 25 healthy control (C) subjects selected from patients and staff. Serum antibodies against Porphyromonas gingivalis and its LPS were analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. Serum triglycerides (TG) and cholesterol (CHOL) were assayed by a commercial laboratory. The associations between AP and blood levels of TG, CHOL, and anti-P. gingivalis whole cells and LPS were examined by logistic regression analysis. Peripheral blood polymorphonuclear leukocytes (PMNs) from 6 healthy fasted donors were incubated with purified TG (0.1 mg/ml) for 2 hours at 37 degrees C, stimulated with 100 ng/ml P. gingivalis LPS, and the release of IL-1beta measured by ELISA.

RESULTS

The presence of periodontitis was significantly associated with age (odds ratio = 3.5, P = 0.04), elevated TG levels (odds ratio = 8.6, P = 0.0009), elevated CHOL levels (odds ratio = 7, P = 0.004), elevated ELISA titer (odds ratio = 35, P = 0.003) and reactivity with P. gingivalis LPS (odds ratio = 41, P = 0.001). PMNs from all 6 healthy patients released modest levels of IL-1beta (10 to 60 pg/ml) when stimulated with 100 ng/ml P. gingivalis LPS. Addition of TG resulted in a significant increase (P <0.05) in IL- 1beta secreted that ranged from 7 to 150% over LPS alone. No IL-1beta was elicited by TG or vehicle alone.

CONCLUSIONS

The results of this study indicate the presence of a significant relationship between periodontitis, hyperlipidemia, and serum antibodies against P. gingivalis LPS that warrants further examination in a larger patient population. Furthermore, these studies indicate that elevated triglycerides are able to modulate IL-1beta production by PMNs stimulated with P. gingivalis LPS.

Heightened gingival inflammation and attachment loss in type 2 diabetics with hyperlipidemia

BACKGROUND

Our previous studies in diabetic (DB) rats suggest that hyperlipidemia may cause a dysregulation of the cellular and local cytokine response to periodontitis (AP). The objective of the present study was to determine if diabetes has a similar dysregulatory effect on the gingival response to AP in humans.

METHODS

Peripheral blood, as well as gingival tissue (GT) and gingival crevicular fluid (GCF), was obtained from a total of 35 patients who were categorized into the following groups based on level of diabetic (type 2) control and presence or absence of adult periodontitis (AP): group 1, systemically and periodontally healthy (n = 6); group 2, systemically healthy with adult periodontitis (n = 7); group 3, well-controlled diabetes and periodontally healthy (n = 6); group 4, well-controlled diabetes with adult periodontitis (n = 5); group 5, poorly controlled diabetes and periodontally healthy (n = 5); group 6, poorly controlled diabetes and adult periodontitis (n = 6). All subjects were given a thorough periodontal examination, including probing depths (PD), clinical attachment levels (CAL), gingival index (GI), plaque index (PI), and vertical bitewing radiographs. Blood studies included levels of glycated hemoglobin (HbA1c), triglycerides (TG), cholesterol (CHL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). The levels of interleukin-1 beta (IL-1beta) in GCF and GT, interleukin-6 (IL-6), and platelet-derived growth factor AB (PDGF-AB) in GT from patients in each experimental group were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our results indicate that all clinical indices except PI were significantly elevated in the poorly controlled and well-controlled diabetics, compared to systemically healthy patients, but only in the subjects without preexisiting AP (Tukey's multiple comparisons, P <0.05). Pairwise linear regression analysis revealed significant (P <0.01) positive associations between periodontal inflammation (PD, CAL, PI, GI) and levels of GCF IL-1beta, GT IL- 1beta GT IL-6, but not GT PDGF; moreover, GT IL-6 levels were significantly associated (P<0.05) with GT IL-1beta. As TG levels increased in the non-AP patients (group 1 < group 3 < group 5), there was a trend, not significant, for increased GCF IL-1beta levels and increased gingival inflammation. Interestingly, periodontitis resulted in increased PDGF-AB levels in the gingiva of systemically healthy and well-controlled diabetes patients, but this increase was obtunded in poorly controlled diabetes patients.

CONCLUSIONS

This confirms our earlier work in the diabetic rat model. These studies indicate that decreased metabolic control in type 2 diabetics results in increased serum triglycerides and has a negative influence on all clinical measures of periodontal health, particularly in patients without preexisting periodontitis. Levels of the cytokine IL- 1beta showed a trend for increasing as diabetic control diminished. In contrast, levels of the growth factor PDGF, which normally increase in periodontitis, decreased in poorly controlled diabetics with periodontitis. These studies suggest a possible dysregulation of the normal cytokine/growth factor signaling axis in poorly controlled type 2 diabetics that may contribute to periodontal breakdown/diminished repair.

Evidence and a novel hypothesis for the role of dendritic cells and Porphyromonas gingivalis in adult periodontitis

We have proposed a novel overall hypothesis and approach to understanding the pathophysiology of adult periodontitis, one of the most common diseases that afflicts the US population. While mortality of the dentition is the most familiar outcome of adult periodontitis, its links with other more severe diseases, including coronary artery disease, respiratory diseases and pre-term labor, cannot be ignored. We have called attention to the many intriguing parallels between adult periodontitis and contact hypersensitivity (CHS). CHS is among the most common of dermatoses that afflicts mankind and one of the most intensively studied of in vivo immune responses. Both adult periodontitis and CHS target the host integument (gingiva or skin) and appear to involve the activation and sensitization of similar subsets of antigen capture and presenting cells, the dendritic cells (DCs), as well as similar T cell subsets. DCs have been termed "nature's adjuvant", being more efficient at antigen-presentation than macrophages or B cells and the only antigen-presenting cells that can stimulate naïve T cells to proliferate. This immunostimulatory capacity can also have detrimental effects for the host, as typified by graft-vs.-host disease and CHS responses. Both AP and CHS involve a predominantly destructive T cell response mediated by both regulatory and effector T cells. In the present paper, we show intriguing evidence that Porphyromonas gingivalis is a unique pathogen in this regard, able to infect, sensitize and activate DCs in vitro and, probably, in situ. Many questions about the role of P. gingivalis-sensitized DCs in adult periodontitis, and of the parallels between adult periodontitis and CHS, however, remain to be answered.

Detection of Bacteroides fragilis in clinical specimens by polymerase chain reaction amplification of the neuraminidase gene

The polymerase chain reaction (PCR) was used in an attempt to detect Bacteroides fragilis by amplifying a segment of the gene encoding B. fragilis neuraminidase. Forty-five reference strains representing 45 species and 113 clinical isolates were tested. Only B. fragilis was PCR positive, except for Bacteroides merdae ATCC 43184, which gave a band by ethidium bromide staining that showed no signal by Southern hybridization. Using a protocol that employed DNA extraction by Sepa Gene kit and a highly sensitive digoxigenin-chemiluminescence detection system, detection of B. fragilis by PCR was in complete agreement with culture results for 44 clinical specimens from which a wide range of aerobic and anaerobic organisms and fungi were recovered.

Cytokine stimulation during Salmonella typhimurium sepsis in Itys mice

Cytokine production was measured in mice during Salmonella typhimurium sepsis and intoxication. In mice given live S. typhimurium (10 cfu/mouse), by intra-peritoneal injection, serum levels of tumour necrosis factor (TNF)-alpha and interleukin-6 increased steadily from day 1 until day 4. Interferon-gamma levels showed a transient peak on day 3. Interleukin-1-alpha levels were very low. There were high bacterial counts in the livers at day 3 and deaths occurred from day 4 onwards. Intraperitoneal injection of lipopolysaccharide or heat-killed bacteria also induced all of the cytokines, but their time of appearance and levels varied greatly. Cytokine induction by heat-killed bacteria was more marked. Endotoxaemia decreased with time during intoxication and increased during sepsis. Bioactive TNF, as measured by a cytotoxicity assay, was found only in mice given heat-killed bacteria.

Comparison of cytokine induction by lipopolysaccharide of Bacteroides fragilis with Salmonella typhimurium in mice

Comparison of cytokine stimulation by lipopolysaccharide (LPS) of Bacteroides fragilis and Salmonella typhimurium was done to study the early events occurring in vivo. Mice injected intraperitoneally with either LPS demonstrated endogenous production of all the cytokines studied (tumor necrosis factor-alpha, interferon-gamma and interleukin-6) within 6 hr in the bloodstream. However induction of all the cytokines by B. fragilis LPS (50 micrograms/mouse) was much weaker compared with S. typhimurium LPS (50 micrograms/mouse). Even a dose of S. typhimurium LPS 40 times smaller (1.2 micrograms/mouse) induced cytokines more strongly compared with B. fragilis LPS. Thus, a weak biological response to B. fragilis LPS as evidenced by chick embryo lethality, limulus lysate gelation, LD50 for mice and rabbit pyrogenicity could be due to weak induction of bioactive mediators by LPS.

Effect of Escherichia coli lipopolysaccharide on Bacteroides fragilis abscess formation and mortality in mice

To study the mechanism of synergism between Bacteroides fragilis and Escherichia coli, the effect of sublethal dose of E. coli lipopolysaccharide (LPS) (25 micrograms/mouse) was checked on B. fragilis abscess formation. LPS was administered prior or after inoculum injection. No significant difference in the abscess size was observed at necropsy on day 6. However, all the groups receiving LPS showed higher incidence of recovery of additional intestinal bacteria (23.5-45.5%) from the abscess pus. When LPS was given 4 hr prior to inoculum administration, 83-100% mortality was observed. Detailed investigation showed autoclaved cecal contents alone could also cause similar mortality. Studies with stimulation of endogenous cytokines by E. coli LPS demonstrated induction of all of them within 3 hr in the blood stream with TNF-alpha demonstrating peak at 1 hr, IL-1 alpha and IL-6 at 4 hr and IFN-gamma between 6-9 hr with moderately high levels at 4 hr. This E. coli LPS-triggered cytokine cascade possibly gets further stimulated by injection of autoclaved cecal contents containing high concentration of endotoxins (1.6 x 10(5) EU/ml) contributed by dead bacteria and lead to the mortality of animals.

In vitro susceptibility of clinical isolates of Bacteroides fragilis and Bacteroides thetaiotaomicron in Japan

A nationwide survey of the susceptibility of 433 isolates of Bacteroides fragilis and 149 isolates of Bacteroides thetaiotaomicron was conducted from December 1986 through November 1989 in Japan. These strains were collected from 16 university hospitals and one metropolitan hospital. Metronidazole was the most active drug against both species, with no resistant isolates found. The activity of imipenem and sulbactam-cefoperazone was good, with very low resistance rates determined in Bacteroides fragilis (1.4% and 1.6%, respectively) and in Bacteroides thetaiotaomicron (3.4% for both drugs), and was comparable to that of metronidazole. Cefoxitin, cefmetazole, cefotetan, cefbuperazone, latamoxef and ceftizoxime were found to be more active against Bacteroides fragilis, for which resistance rates were 3.2 to 9.5%, than against Bacteroides thetaiotaomicron, for which resistance rates were 18.1 to 21.8%. Rates of piperacillin resistance in the two species were 12.9% and 26.8%, respectively. Clindamycin was very active at a low concentration (MIC50 of 0.39 to 1.56 mg/l), but 24% and 27.5% of Bacteroides fragilis and Bacteroides thetaiotaomicron isolates, respectively, were resistant to this agent.

Pathogenicity of Bacteroides fragilis group in rat intra-abdominal abscesses

Attempts were made to study the pathogenicity of some strains of Bacteroides fragilis group in the rat intra-abdominal abscess model. Multiple intraabdominal abscesses were produced in 50 to 70% of animals when an inoculum containing 10(9) CFU/ml of any of the five species of Bacteroides fragilis group was injected. Rising homologous antibody titers determined by indirect fluorescent antibody test were observed till the 3rd week when tested last, indirectly confirming the multiplication of the organisms as also evident by viable count of bacteria in the abscesses. In some cases in addition to inoculated organisms some intestinal bacteria like Escherichia coli, Proteus mirabilis and Streptococcus spp. were also recovered from the abscess pus. Studies with the electron microscope showed presence of capsular polysaccharide only in Bacteroides fragilis and Bacteroides thetaiotaomicron. It was doubtful in Bacteroides distasonis and absent in Bacteroides ovatus and Bacteroides vulgatus, suggesting that virulence factor beside the capsular polysaccharide may be playing a role. Further studies are required to investigate the virulence factor responsible for the pathogenicity of noncapsulated species.

Virulence factors in Bacteroides fragilis group

Attempts were made to study the virulence factors in some strains of B. fragilis group in the rat model. Subcutaneous wound abscesses could be produced by 10(9) CFU/ml of live cells of all the five species of B. fragilis group tested. For determination of virulence factor cellular components (capsular polysaccharide and lipopolysaccharide) of B. fragilis were separated using gel filtration technique and injected in rats. Abscesses could be produced only by capsular polysaccharide fraction suggesting it to be the virulence factor. Studies with transmission electron microscope showed presence of capsular polysaccharide in B. fragilis and B. thetaiotaomicron, it was doubtful in B. distasonis and absent in B. ovatus and B. vulgatus. This suggested that virulence factors other than capsular polysaccharide may be responsible for pyogenic lesions in the noncapsulated species of B. fragilis group. The abscess could not be produced by 10(9) CFU/ml of heat killed cells of non-capsulated B. ovatus and B. vulgatus indicating that in live bacteria, a heat labile factor was responsible for the development of abscess.