Intraoperative Assessment of Resection Margin in Oral Cancer: The Potential Role of Spectroscopy.

In parallel with the increasing number of oncological cases, the need for faster and more efficient diagnostic tools has also appeared. Different diagnostic approaches are available, such as radiological imaging or histological staining methods, but these do not provide adequate information regarding the resection margin, intraoperatively, or are time consuming. The purpose of this review is to summarize the current knowledge on spectrometric diagnostic modalities suitable for intraoperative use, with an emphasis on their relevance in the management of oral cancer. The literature agrees on the sensitivity, specificity, and accuracy of spectrometric diagnostic modalities, but further long-term prospective, multicentric clinical studies are needed, which may standardize the intraoperative assessment of the resection margin and the use of real-time spectroscopic approaches.

Current approaches to the diagnosis and management of odontogenic abscesses / Odontogén tályogok diagnosztikája és kezelése a nemzetközi ajánlások tükrében

A wide scale of medical professionals including general practitioners, dentists, maxillofacial surgeons, otolaryngologists or even emergency physicians frequently encounter patients suffering from abscesses of odontogenic origin. These dental infections spreading along the fascial planes into the adjacent anatomical spaces or by the lymphatic vessels and veins may result in life-threatening situations. It is essential to prevent and - in the case of an evolved disease pattern - to treat them properly, since improper or delayed treatment may entail avoidable burdens on the healthcare system. Our aim was to review the current literature regarding the development, diagnostics and treatment of odontogenic infections. A review of the English and Hungarian literature was performed. Considerations regarding the surgical management of dental abscesses have well-tried, traditional routes. Prompt intervention is considered mandatory with surgical decompression of the swelling by performing incision and drainage. A rapid improvement of radiology has provided the possibility to realize and avoid fatal consequences of this disorder. The administration route, necessity and duration of empiric antibiotic therapy are still debated, protocols vary across studies. Based on inconsistency in findings among the studies and lack of high-quality prospective studies, future research should evaluate evidence-based and effective management of dental abscesses.

Augmentation of the vertical bone defects of the mandible and maxilla with autogenous bone block / A mandibula és a maxilla vertikális csonthiányainak autológ csontblokkal végzett augmentációja. Utánkövetéses retrospektív tanulmány

Introduction: Vertical augmentation of the alveolar process for dental implantation is a well-established approach. The literature suggests that vertical ridge augmentation is associated with an elevated risk of complications and bone resorption compared to lateral bone augmentation or sinus elevation. Objective: We sought to retrospectively analyze the long-term success of vertical augmentation in terms of bone stability and complications. Method: We reviewed the medical records of 186 patients who underwent monocortical bone augmentation and nar-rowed them down to two smaller groups. Patients in one group were treated by sinus elevation, while patients in the other group were treated by vertical ridge augmentation. In both groups, the treatment was carried out utilizing autogenous monocortical bone blocks. Only those files were selected for analysis where follow-up documentation of a minimum of 3 years with panoramic X-ray images was available. We analyzed the frequency and degree of bone resorption and the frequency of implant loss and complications. Results: 72% of the augmentation cases and 92% of the implants in the sinus elevation group were free of bone resorp-tion in contrast to the vertical ridge augmentation group where only 46% of the augmentation cases and 24% of the implants were free of bone resorption. No implant loss or peri-implant complications were observed in either group. Conclusion: The results support the literature in that the risk of bone resorption is higher in cases of vertical ridge augmentation. However, this was not accompanied by functional alterations, peri-implant complications, or inflam-matory phenomena and neither did it lead to implant loss, even in cases with more than a decade of follow-up.

Cross-modality imaging of bisphosphonate-treated murine jawbones.

In this proof-of-principle study, we established and implemented a cross-modality imaging (CMI) pipeline to characterize and compare bisphosphonate (BIS)-treated jawbones of Sprague-Dawley rats after tooth extraction after physical therapies (photobiomodulation and extracorporeal shockwave therapy (PBMT and ESWT)). We showcase the feasibility of such a CMI approach and its compatibility across imaging modalities to probe the same region of interest (ROI) of the same jawbone. Jawbones were imaged in toto in 3D using micro-Computed Tomography to identify ROIs for subsequent sequential 2D analysis using well-established technologies such as Atomic Force Microscopy and Scanning Electron Microscopy, and recent imaging approaches in biomedical settings, such as micro-X-Ray Fluorescence Spectroscopy. By combining these four modalities, multiscale information on the morphology, topography, mechanical stiffness (Young's modulus), and calcium, zinc and phosphorus concentrations of the bone was collected. Based on the CMI pipeline, we characterized and compared the jawbones of a previously published clinically relevant rat model of BIS-related osteonecrosis of the jawbone (BRONJ) before and after treatment with BISs, PBMT and ESWT. While we did not find that physical therapies altered the mechanical and elemental jawbone parameters with significance (probably due to the small sample size of only up to 5 samples per group), both ESWT and PBMT reduced pore thicknesses and bone-to-enamel distances significantly compared to the controls. Although focused on BIS-treated jawbones, the established CMI platform can be beneficial in the study of bone-related diseases in general (such as osteoarthritis or -porosis) to acquire complementary hallmarks and better characterize disease status and alleviation potentials.

[Current evidence-based approaches and international guidelines in primary and secondary prevention strategies of medication-related osteonecrosis of the jaws]. / Aktualitások a gyógyszer okozta állcsontelhalás primer és szekunder prevenciójának stratégiájában az evidenciák és a nemzetközi ajánlások tükrében.

Introduction: The presumably multifactorial pathomechanisms of medication-related osteonecrosis of the jaws have not been fully elucidated so far. Management of this rare but serious side effect is a real challenge and requires a multidisciplinary approach. Aim: The aim of the authors was to take stock of our present knowledge about the pathogenesis, risk factors, clinical manifestations and the possibilities of prevention and treatment in the medication-related osteonecrosis of the jaws. In addition, the available international guidelines are compared and the evidence-based, stage-specific conservative and adjuvant therapeutic approaches are also reviewed, having regard to special aspects of medical and dental care. Method: In the last 5 years - due to the increasing number of disorder-oriented database - the number of available systematic reviews, recommendations and meta-analyses has escalated significantly which we reviewed and compared. Results: Since the last Position Paper published by the taskforce of the American Association of Oral and Maxillofacial Surgeons, novel pharmacological groups with the potential to induce osteonecrosis have come in the clinical scope, further elaborating the nomenclature of the disease and further specifying patient groups. The sphere of patients at risk has broadened and novel patient groups (rheumatologic-osteological, immunosuppressed, transplanted or oncological patients treated with monoclonal antibody, known as 'target therapy') are expected to develop this serious side effect. Conclusion: Although a number of issues are still open regarding the treatment of the disorder, evidence-based, individualized, stage-adapted therapeutic approaches have replaced the previous empirical treatment. Orv Hetil. 2020; 161(6): 214-223.

Cloud-Based Multicenter Data Collection and Epidemiologic Analysis of Bisphosphonate-Related Osteonecrosis of the Jaws in a Central European Population.

Objective: Bisphosphonate-related osteonecrosis of the jaws is considered to be a rare but severe complication of bisphosphonate therapy. To understand this condition better, data collection is essential. Although the number of scientific papers about this subject is large, to date only a few multicenter reports have been published. Study design: We present a novel cloud-based data collection system for the evaluation of the risk factors of bisphosphonate-related osteonecrosis of the jaws. Web-based questionnaire and database have been set up and made available to voluntary researchers and clinicians in oral and maxillofacial surgery in Hungary and Slovakia. Results: To date, fifteen colleagues from eight maxillofacial units have joined the study. Data of 180 patients have been recorded. Collected data were statistically analysed and evaluated from an epidemiological point of view. Conclusions: Authors consider cloud-based multicenter data collection a useful tool that allows for real-time collaboration between users, facilitates fast data entry and analysis, and thus considerably contributes to widening our knowledge of bisphosphonate-related osteonecrosis of the jaws.

Effects of goal-directed crystalloid vs. colloid fluid therapy on microcirculation during free flap surgery: A randomised clinical trial.

BACKGROUND: Macro, and microcirculatory effects of crystalloids and colloids are difficult to compare, because interventions to achieve haemodynamic stability seldom follow similar criteria. OBJECTIVES: Our aim was to compare the effects of crystalloids and colloids on the microcirculation during free flap surgery when management was guided by detailed haemodynamic assessment. DESIGN: A randomised, controlled clinical trial. SETTINGS: The investigation was performed at the University of Szeged, Hungary. PATIENTS: Patients undergoing maxillofacial tumour resection and free flap reconstruction were randomised into groups treated with either intra-operative crystalloid (Ringerfundin, n = 15) or colloid (6% hydroxyethyl starch, HES, n = 15) solutions. INTERVENTIONS: Macrohaemodynamics were monitored by a noncalibrated device (PulsioFlex-PULSION). Central venous oxygen saturation, venous-to-arterial PCO2-gap, lactate levels and urine output were measured hourly. Maintenance fluid was Ringerfundin (1 ml kg h), and a multimodal, individualised, approach-based algorithm was applied to guide haemodynamic support. Hypovolaemia was treated with Ringerfundin or HES fluid boluses, respectively. The microcirculatory effects were assessed by laser-Doppler flowmetry (PeriFlux 5000 LDPM), with the probe placed on the flap and on a control area. Measurements were performed after the flap was prepared, then 1 and 12 h later. MAIN OUTCOME MEASURES: The primary end-point was microcirculatory perfusion as determined by laser-Doppler flowmetry. RESULTS: There was no difference between the groups regarding patient characteristics. Both groups remained haemodynamically stable throughout due to the use of approximately a 1.5 times higher total fluid volume in the Ringerfundin group than in the HES group: mean ±â€ŠSD: 2581 ±â€Š986 and 1803 ±â€Š497) ml, respectively, (P = 0.011). There was no significant difference in the microcirculatory blood flow between the groups. CONCLUSION: Our results showed that when fluid management was guided by detailed haemodynamic assessment, more crystalloid than colloid was needed to maintain haemodynamic stability, but there was no difference between the effects of crystalloids and colloids on the microcirculation. TRIAL REGISTRATION: ClinicalTrials.gov NCT03288051.

Microcirculatory consequences of limb ischemia/reperfusion in ovariectomized rats treated with zoledronic acid.

BACKGROUND: Nitrogen-containing bisphosphonates (BIS) are potent therapeutics in osteoporosis, but their use may result in osteonecrotic side-effects in the maxillofacial region. Periosteal microcirculatory reactions may contribute to the development of bone-healing complications, particularly in osteoporotic bones, where ischemia-reperfusion (IR) events often develop during orthopaedic/trauma interventions. The effect of BIS on the inflammatory reactions of appendicular long bones has not yet been evaluated; thus, we aimed to examine the influence of chronic zoledronate (ZOL) administration on the periosteal microcirculatory consequences of hindlimb IR in osteopenic rats. MATERIALS AND METHODS: Twelve-week-old female Sprague-Dawley rats were ovariectomized (OVX) or sham-operated, and ZOL (80 µg/kg iv, weekly) or a vehicle was administered for 8 weeks, 4 weeks after the operation. At the end of the pre-treatment protocols, 60-min limb ischemia was induced, followed by 180-min reperfusion. Leukocyte-endothelial interactions were quantitated in tibial periosteal postcapillary venules by intravital fluorescence videomicroscopy. CD11b expression of circulating polymorphonuclear leukocytes (PMN, flow cytometry) and plasma TNF-alpha levels (ELISA) were also determined. Two-way RM ANOVA followed by the Holm-Sidak and Dunn tests was used to assess differences within and between groups, respectively. RESULTS: Limb IR induced significant increases in PMN rolling and firm adhesion in sham-operated and OVX rats, which were exacerbated temporarily in the first 60 min of reperfusion by a ZOL treatment regimen. Postischemic TNF-alpha values showed a similar level of postischemic elevations in all groups, whereas CD11b expression only increased in rats not treated with ZOL. CONCLUSIONS: The present data do not show substantial postischemic periosteal microcirculatory complications after chronic ZOL treatment either in sham-operated or OVX rats. The unaltered extent of limb IR-induced local periosteal microcirculatory reactions in the presence of reduced CD11b adhesion molecule expression on circulating PMNs, however, may be attributable to local endothelial injury/activation caused by ZOL.

An anterolateral thigh chimeric flap for dynamic facial and esthetic reconstruction after oncological surgery in the maxillofacial region: a case report.

BACKGROUND: The surgical management of malignant tumors in the head and neck region often leads to functional and esthetic defects that impair the quality of life of the patients. Reconstruction can be solved with prostheses in these cases, but various types of microsurgical free flaps can provide a better clinical outcome. CASE PRESENTATION: In this case report, the tumor and parts of the involved facial muscles and nerve were excised surgically from a 42-year-old patient after a third relapse of basal cell carcinoma in the left midface. The tissue defect was reconstructed with an anterolateral thigh chimeric type I fascio-myocutaneous flap, where the facial palsy was restored with a segmental branch of the femoral nerve and the involved mouth corner elevator muscles for the segmented vastus lateralis muscle. The 6-month follow-up revealed a good esthetic outcome, the soft tissue defect reconstruction with good functional activity of the reconstructed facial nerve and with acceptable mimic movements. There has been no subsequent recurrence. CONCLUSIONS: It is concluded that the chimeric type I anterolateral fascio-myocutaneous free flap can offer a good option for the esthetic and functional reconstruction of an extensive tissue defect in the maxillofacial region.

Estrogen-dependent efficacy of limb ischemic preconditioning in female rats.

Our aim was to examine the effects of ischemic preconditioning (IPC) on the local periosteal and systemic inflammatory consequences of hindlimb ischemia-reperfusion (IR) in Sprague-Dawley rats with chronic estrogen deficiency (13 weeks after ovariectomy, OVX) in the presence and absence of chronic 17beta-estradiol supplementation (E2, 20 µg kg-1 , 5 days/week for 5 weeks); sham-operated (non-OVX) animals served as controls. As assessed by intravital fluorescence microscopy, rolling and the firm adhesion of polymorphonuclear neutrophil leukocytes (PMNs) gave similar results in the Sham + IR and OVX + IR groups in the tibial periosteal microcirculation during the 3-h reperfusion period after a 60-min tourniquet ischemia. Postischemic increases in periosteal PMN adhesion and PMN-derived adhesion molecule CD11b expressions, however, were significantly reduced by IPC (two cycles of 10'/10') in Sham animals, but not in OVX animals; neither plasma free radical levels (as measured by chemiluminescence), nor TNF-alpha release was affected by IPC. E2 supplementation in OVX animals restored the IPC-related microcirculatory integrity and PMN-derived CD11b levels, and TNF-alpha and free radical levels were reduced by IPC only with E2. An enhanced estrogen receptor beta expression could also be demonstrated after E2 in the periosteum. Overall, the beneficial periosteal microcirculatory effects of limb IPC are lost in chronic estrogen deficiency, but they can be restored by E2 supplementation. This suggests that the presence of endogenous estrogen is a necessary facilitating factor of the anti-inflammatory protection provided by limb IPC in females. The IPC-independent effects of E2 on inflammatory reactions should also be taken into account in this model. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:97-105, 2018.

Surgical Management of Progressive Hemifacial Atrophy With De-Epithelialized Profunda Artery Perforator Flap: A Case Report.

Progressive hemifacial atrophy (PHA) is a rare disorder characterized by slow, unilateral atrophy of the soft tissues and bones of the craniofacial region. The defect becomes more pronounced with age, leading to esthetic and functional deficits. However, the proper timing and method of surgical reconstruction are still debated. The correction of this defect markedly influencing the quality of life of the patient can be achieved with less invasive to more invasive surgical approaches. A 21-year-old female patient with hemifacial atrophy and extensive alopecia presented to our clinic. Considering the body type and the expectations of the patient, a profunda artery perforator flap was applied for the reconstruction and esthetic improvement of the facial region. The facial asymmetry attenuated after the reconvalescence period. This case shows that in the up-to-date surgical treatment of severe PHA, the use of microvascular free flaps may provide a better approach when trying to achieve an acceptable esthetic result. This is the first time that a profunda artery perforator flap was used to restore facial asymmetry caused by PHA.

The periosteal microcirculation in health and disease: An update on clinical significance.

Apart from its nutritive functions, the periosteum critically affects bone regeneration via its stem/osteoprogenitor cell content. Normal healing after bone fractures, trauma-orthopedic interventions and invasive dental procedures is critically linked to the reestablishment of the periosteal microcirculation, but the reconstruction, replacement or repair of lost tissues may also be performed with autologous periosteum. Besides the initiation of cell differentiation during bone repair and remodeling processes, the periosteum together with the endosteum plays significant roles in the pathogenesis of both hormone-related and trauma-induced osteoporotic alterations in the bone metabolism. Nevertheless, the axial bones, and in particular the jawbones, and the appendicular bones display differences not only in their blood supply and fracture healing characteristics, but also in respect of the development of osteoporosis and their reactions to treatment modalities (i.e. bisphosphonates). These reactions may also be linked to the differences in periosteal microcirculatory reactions. The present overview summarizes the relevant data of microcirculatory studies focusing on the periosteal reactions in different anatomical locations together with the optimal background methodologies, study models and the most significant observations.

Periosteal microcirculatory reactions in a zoledronate-induced osteonecrosis model of the jaw in rats.

OBJECTIVES: Nitrogen-containing bisphosphonates induce osteonecrosis mostly in the jaw and less frequently in other bones. Because of the crucial role of periosteal perfusion in bone repair, we investigated zoledronate-induced microcirculatory reactions in the mandibular periosteum in comparison with those in the tibia in a clinically relevant model of bisphosphonate-induced medication-related osteonecrosis of the jaw (MRONJ). MATERIALS AND METHODS: Sprague-Dawley rats were treated with zoledronate (ZOL; 80 i.v. µg/kg/week over 8 weeks) or saline vehicle. The first two right mandibular molar teeth were extracted after 3 weeks. Various systemic and local (periosteal) microcirculatory inflammatory parameters were examined by intravital videomicroscopy after 9 weeks. RESULTS: Gingival healing disorders (∼100%) and MRONJ developed in 70% of ZOL-treated cases but not after saline (shown by micro-CT). ZOL induced significantly higher degrees of periosteal leukocyte rolling and adhesion in the mandibular postcapillary venules (at both extraction and intact sites) than at the tibia. Leukocyte NADPH-oxidase activity was reduced; leukocyte CD11b and plasma TNF-alpha levels were unchanged. CONCLUSION: Chronic ZOL treatment causes a distinct microcirculatory inflammatory reaction in the mandibular periosteum but not in the tibia. The local reaction in the absence of augmented systemic leukocyte inflammatory activity suggests that topically different, endothelium-specific changes may play a critical role in the pathogenesis of MRONJ. CLINICAL RELEVANCE: This model permits for the first time to explore the microvascular processes in the mandibular periosteum after chronic ZOL treatment. This approach may contribute to a better understanding of the pathomechanism and the development of strategies to counteract bisphosphonate-induced side effects.

[Current approaches for early detection and treatment of medication-related osteonecrosis of jaw]. / Aktuális trendek a gyógyszer indukálta állcsontnecrosis korai felismerése és kezelési stratégiája terén.

Owing to the increased life expectancy, the incidence of rheumatoid disorders and oncologic cases with bone metastasis has dramatically increased. Despite the beneficial effects of the applied antiresorptive and antiangiogenic drugs (e.g. bisphosphonates), serious side effects such as jaw osteonecrosis may also develop. The aim of the authors was to summarize present knowledge about the possibilities of prevention and treatment in medication-related osteonecrosis of the jaw. Based on literature data, currently used detection methods for medication-related osteonecrosis of the jaw (including their advantages and limitations) are summarized. In addition, novel trends of surgical and adjuvant therapeutic approaches are also reviewed. The authors conclude that possibilities of prevention and efficacy of therapeutic interventions in this disorder are still limited possibly due to an incomplete knowledge of the underlying pathomechanism. An interdisciplinary cooperation for prevention and attentive monitoring in order to decrease the incidence of iatrogenic oral and maxillofacial complications seems to be particularly important.

Microcirculatory effects of selective endothelin-A receptor antagonism in testicular torsion.

PURPOSE: Testicular torsion without timely intervention causes incurable damage to the testis. We examined the causative role of microcirculatory injury in torsion induced testicular damage with particular regard to endothelin-A receptor activation. MATERIALS AND METHODS: The microcirculatory consequences of testicular torsion were assessed in the presence or absence of endothelin-A receptor antagonism in rats. Microcirculatory perfusion changes (red blood cell velocity and pulsatile flow pattern alterations) were examined by an orthogonal polarization spectral imaging technique. Microcirculatory inflammatory alterations were assessed by fluorescence intravital video microscopy after 60-minute torsion followed by 240-minute reperfusion. As a specific endothelin-A receptor inhibitor, the antisense homology box derived peptide ETR-p1/fl was applied 10 minutes before reperfusion. Tissue accumulation of leukocytes was estimated by myeloperoxidase activity in tissue biopsies taken at the end of the 4-hour reperfusion period. In further experiments testicular weight as a marker of permanent damage was evaluated 45 days after torsion. RESULTS: The physiological pulsatile flow pattern ceased in the initial phase of reperfusion while leukocyte-endothelial interactions increased throughout the examined reperfusion period. Endothelin-A receptor antagonism caused earlier return of pulsatile flow and recovery of red blood cell velocity, and alleviated microcirculatory inflammatory reactions and atrophy. CONCLUSIONS: Results suggest a pathophysiological role of endothelin-A receptor activation in the pathogenesis of testicular torsion. This effect is related to deterioration in testicular perfusion and activation of microcirculatory inflammatory reactions.

A novel method for in vivo visualization of the microcirculation of the mandibular periosteum in rats.

OBJECTIVE: The periosteum plays an important role in bone physiology, but observation of its microcirculation is greatly limited by methodological constraints at certain anatomical locations. This study was conducted to develop a microsurgical procedure which provides access to the mandibular periosteum in rats. METHODS: Comparisons of the microcirculatory characteristics with those of the tibial periosteum were performed to confirm the functional integrity of the microvasculature. The mandibular periosteum was reached between the facial muscles and the anterior surface of the superficial masseter muscle at the external surface of the mandibular corpus; the tibial periosteum was prepared by dissecting the covering muscles at the anteromedial surface. Intravital fluorescence microscopy was used to assess the leukocyte-endothelial interactions and the RBCV in the tibial and mandibular periosteum. Both structures were also visualized through OPS and fluorescence CLSM. RESULTS: The microcirculatory variables in the mandibular periosteum proved similar to those in the tibia, indicating that no microcirculatory failure resulted from the exposure technique. CONCLUSION: This novel surgical approach provides simple access to the mandibular periosteum of the rat, offering an excellent opportunity for investigations of microcirculatory manifestations of dentoalveolar and maxillofacial diseases.

The role of pancreatic ductal secretion in protection against acute pancreatitis in mice*.

OBJECTIVES: A common potentially fatal disease of the pancreas is acute pancreatitis, for which there is no treatment. Most studies of this disorder focus on the damage to acinar cells since they are assumed to be the primary target of multiple stressors affecting the pancreas. However, increasing evidence suggests that the ducts may also have a crucial role in induction of the disease. To test this hypothesis, we sought to determine the specific role of the duct in the induction of acute pancreatitis using well-established disease models and mice with deletion of the Na/H exchanger regulatory factor-1 that have selectively impaired ductal function. DESIGN: Randomized animal study. SETTING: Animal research laboratory. SUBJECTS: Wild-type and Na/H exchanger regulatory factor-1 knockout mice. INTERVENTIONS: Acute necrotizing pancreatitis was induced by i.p. administration of cerulein or by intraductal administration of sodium taurocholate. The pancreatic expression of Na/H exchanger regulatory factor-1 and cystic fibrosis transmembrane conductance regulator (a key player in the control of ductal secretion) was analyzed by immunohistochemistry. In vivo pancreatic ductal secretion was studied in anesthetized mice. Functions of pancreatic acinar and ductal cells as well as inflammatory cells were analyzed in vitro. MEASUREMENTS AND MAIN RESULTS: Deletion of Na/H exchanger regulatory factor-1 resulted in gross mislocalization of cystic fibrosis transmembrane conductance regulator, causing marked reduction in pancreatic ductal fluid and bicarbonate secretion. Importantly, deletion of Na/H exchanger regulatory factor-1 had no deleterious effect on functions of acinar and inflammatory cells. Deletion of Na/H exchanger regulatory factor-1, which specifically impaired ductal function, increased the severity of acute pancreatitis in the two mouse models tested. CONCLUSIONS: Our findings provide the first direct evidence for the crucial role of ductal secretion in protecting the pancreas from acute pancreatitis and strongly suggest that improved ductal function should be an important modality in prevention and treatment of the disease.

Methane biogenesis during sodium azide-induced chemical hypoxia in rats.

Previous studies demonstrated methane generation in aerobic cells. Our aims were to investigate the methanogenic features of sodium azide (NaN(3))-induced chemical hypoxia in the whole animal and to study the effects of l-α-glycerylphosphorylcholine (GPC) on endogenous methane production and inflammatory events as indicators of a NaN(3)-elicited mitochondrial dysfunction. Group 1 of Sprague-Dawley rats served as the sham-operated control; in group 2, the animals were treated with NaN(3) (14 mg·kg(-1)·day(-1) sc) for 8 days. In group 3, the chronic NaN(3) administration was supplemented with daily oral GPC treatment. Group 4 served as an oral antibiotic-treated control (rifaximin, 10 mg·kg(-1)·day(-1)) targeting the intestinal bacterial flora, while group 5 received this antibiotic in parallel with NaN(3) treatment. The whole body methane production of the rats was measured by means of a newly developed method based on photoacoustic spectroscopy, the microcirculation of the liver was observed by intravital videomicroscopy, and structural changes were assessed via in vivo fluorescent confocal laser-scanning microscopy. NaN(3) administration induced a significant inflammatory reaction and methane generation independently of the methanogenic flora. After 8 days, the hepatic microcirculation was disturbed and the ATP content was decreased, without major structural damage. Methane generation, the hepatic microcirculatory changes, and the increased tissue myeloperoxidase and xanthine oxidoreductase activities were reduced by GPC treatment. In conclusion, the results suggest that methane production in mammals is connected with hypoxic events associated with a mitochondrial dysfunction. GPC is protective against the inflammatory consequences of a hypoxic reaction that might involve cellular or mitochondrial methane generation.