[Typical emergencies in otorhinolaryngology-a monocentric analysis of the seasonal course]

Hintergrund

Die Inzidenz der Akutdiagnosen im Hals-Nasen-Ohren(HNO)-Bereich wird durch multiple Parameter beeinflusst, unter anderem meteorologische und saisonale Einflüsse. Durch ein besseres Verständnis dieser Faktoren könnten prophylaktische Ansätze entwickelt werden.

Material und Methoden

Über 6 Jahre erfolgte eine retrospektive Analyse aller Patienten, die sich aufgrund von typischen und weniger komplexen HNO-ärztlichen Krankheitsbildern wie Cerumen obturans, akuter Otitis externa und media, Nasenpyramidenfraktur, Epistaxis nasi, akuter Tonsillitis, akuter Rhinosinusitis oder eines Peritonsillarabszess in einer südwestdeutschen Universitätsklinik vorgestellt haben.

Ergebnisse

32.968 Fälle wurden ausgewertet. Mit 24,5 % (8082 Fälle) war die Epistaxis nasi die häufigste Notfalldiagnose. Diese, wie auch die akute Otitis media und die akute Rhinosinusitis, traten signifikant häufiger in der kälteren Jahreshälfte auf. Es bestand keine signifikante Korrelation der Diagnose Nasenpyramidenfraktur mit besonderen Zeiten wie Feiertagen. Die akute Otitis externa korrelierte signifikant mit dem Zeitraum der Sommerferien. In Kalenderwoche 38 gab es die wenigsten und in der Kalenderwoche 52 die meisten Notfallvorstellungen.

Schlussfolgerung

Saisonale und meteorologische Faktoren spielen eine Rolle in der Krankheitsentstehung verschiedener HNO-ärztlicher Notfalldiagnosen.

Performance of microvascular anastomosis with a new robotic visualization system: proof of concept

Microvascular procedures require visual magnification of the surgical field, e.g. by a microscope. This can be accompanied by an unergonomic posture with musculoskeletal pain or long-term degenerative changes as the eye is bound to the ocular throughout the whole procedure. The presented study describes the advantages and drawbacks of a 3D exoscope camera system. The RoboticScope^®-system (BHS Technologies^®, Innsbruck, Austria) features a high-resolution 3D-camera that is placed over the surgical field and a head-mounted-display (HMD) that the camera pictures are transferred to. A motion sensor in the HMD allows for hands-free change of the exoscope position via head movements. For general evaluation of the system functions coronary artery anastomoses of ex-vivo pig hearts were performed. Second, the system was evaluated for anastomosis of a radial-forearm-free-flap in a clinical setting/in vivo. The system positioning was possible entirely hands-free using head movements. Camera control was intuitive; visualization of the operation site was adequate and independent from head or body position. Besides technical instructions of the providing company, there was no special surgical training of the surgeons or involved staff upfront performing the procedures necessary. An ergonomic assessment questionnaire showed a favorable ergonomic position in comparison to surgery with a microscope. The outcome of the operated patient was good. There were no intra- or postoperative complications. The exoscope facilitates a change of head and body position without losing focus of the operation site and an ergonomic working position. Repeated applications have to clarify if the system benefits in clinical routine.

[Robotics in otorhinolaryngology, head and neck surgery]

In many surgical specialities, e.g., visceral surgery or urology, the use of robotic assistance is widely regarded as standard for many interventions. By contrast, in European otorhinolaryngology, robotic-assisted surgery (RAS) is rarely conducted. This is because currently available robotic systems are not adequately adapted to the restricted space and partially difficult access to surgical fields in the head and neck area. Furthermore, RAS is associated with high costs at present. In some Anglo-American regions, robot-assisted surgery is already used regularly for different indications, particularly in transoral surgery of oropharyngeal tumors. Several feasibility studies demonstrate multiple fields of application for RAS in head and neck surgery. For standard use, the robotic systems and surgical instruments need to be reduced in size and adapted to application in the head and neck area.

Influence of travel burden on tumor classification and survival of head and neck cancer patients

PURPOSE

Cancer patients have to overcome various barriers to obtain diagnostics and treatment at head and neck cancer centers. Travel distance to a specialized hospital may result in psychosocial and financial distress, thus interfering with diagnostics, treatment, and follow-up care. In this study, we have aimed to analyze the association of travel distance with cTNM status, UICC stage at primary diagnosis, and survival outcomes of head and neck cancer (HNC) patients.

METHODS

We have analyzed data of 1921 consecutive HNC patients diagnosed between 2014 and 2019 at the head and neck cancer center of the Comprehensive Cancer Center Ulm (CCCU), Germany. Postal code-based travel distance calculation in kilometers, TNM status, and UICC stage were recorded at initial diagnosis. The assembly of travel distance-related groups (short, intermediate, long-distance) has been investigated. Moreover, group-related survival and recurrence analysis have been performed.

RESULTS

In contrast to observations from overseas, no association of travel distance and higher cTNM status or UICC stage at primary diagnosis has been observed. Furthermore, no significant differences for recurrence-free survival and overall survival by travel distance were detected.

CONCLUSION

In southern Germany, travel distance to head and neck cancer centers seems to be tolerable. Travel burden is not synonymous with travel distance alone but also involves sociodemographic, monetary, and disease-specific aspects as well as accessibility to proper infrastructure of transport and health care system.

Metaproteome analysis reveals that syntrophy, competition, and phage-host interaction shape microbial communities in biogas plants

BACKGROUND

In biogas plants, complex microbial communities produce methane and carbon dioxide by anaerobic digestion of biomass. For the characterization of the microbial functional networks, samples of 11 reactors were analyzed using a high-resolution metaproteomics pipeline.

RESULTS

Examined methanogenesis archaeal communities were either mixotrophic or strictly hydrogenotrophic in syntrophy with bacterial acetate oxidizers. Mapping of identified metaproteins with process steps described by the Anaerobic Digestion Model 1 confirmed its main assumptions and also proposed some extensions such as syntrophic acetate oxidation or fermentation of alcohols. Results indicate that the microbial communities were shaped by syntrophy as well as competition and phage-host interactions causing cell lysis. For the families Bacillaceae, Enterobacteriaceae, and Clostridiaceae, the number of phages exceeded up to 20-fold the number of host cells.

CONCLUSION

Phage-induced cell lysis might slow down the conversion of substrates to biogas, though, it could support the growth of auxotrophic microbes by cycling of nutrients.

[The ulm emergency algorithm for the acute treatment of drug-induced, bradykinin-mediated angioedema]

BACKGROUND

Bradykinin-mediated, drug-induced edema like ACE-inhibitor-induced angioedema (ACEi AE) is almost exclusively located in the head and neck region and is potentially life threatening. To date, there are no guidelines or officially-approved treatments available for this pathology.

OBJECTIVES

We sought to provide a structured therapeutic algorithm for the acute treatment of drug-induced bradykinin-mediated angioedema.

MATERIALS AND METHODS

We analyzed data (especially the course of disease and therapy) of all patients with acute angioedema, who presented to the Department of Otorhinolaryngology, Head and Neck Surgery at the University of Ulm (2010-2015). We also conducted a literature review on PubMed with the terms "acute angioedema", "angioedema emergency", "ACE angioedema", "bradykinin angioedema" and "angioedema therapy". Other fundamental references were the recent German guidelines "hereditary angioedema", "anaphylaxis" and "airway management".

RESULTS

An emergency algorithm was generated as a flowchart for the acute therapy of bradykinin-mediated drug-induced angioedema was generated. We focused on the decision criteria for intubation/airway management and pharmacological therapy: antihistamines and glucocorticoids versus anti-bradykinin treatment. Furthermore, recommendations for inpatient monitoring have been derived.

CONCLUSION/DISCUSSION

To date, therapy of drug-induced bradykinin-mediated angioedema is performed according to an "off-label" use and without officially-approved guidelines. The presented emergency algorithm provides a first approach for a structured therapeutic concept for a potentially life-threatening pathology.

An Innovate Robotic Endoscope Guidance System for Transnasal Sinus and Skull Base Surgery: Proof of Concept

Objective  Advanced transnasal sinus and skull base surgery remains a challenging discipline for head and neck surgeons. Restricted access and space for instrumentation can impede advanced interventions. Thus, we present the combination of an innovative robotic endoscope guidance system and a specific endoscope with adjustable viewing angle to facilitate transnasal surgery in a human cadaver model. Materials and Methods  The applicability of the robotic endoscope guidance system with custom foot pedal controller was tested for advanced transnasal surgery on a fresh frozen human cadaver head. Visualization was enabled using a commercially available endoscope with adjustable viewing angle (15-90 degrees). Results  Visualization and instrumentation of all paranasal sinuses, including the anterior and middle skull base, were feasible with the presented setup. Controlling the robotic endoscope guidance system was effectively precise, and the adjustable endoscope lens extended the view in the surgical field without the common change of fixed viewing angle endoscopes. Conclusion  The combination of a robotic endoscope guidance system and an advanced endoscope with adjustable viewing angle enables bimanual surgery in transnasal interventions of the paranasal sinuses and the anterior skull base in a human cadaver model. The adjustable lens allows for the abandonment of fixed-angle endoscopes, saving time and resources, without reducing the quality of imaging.

Synchronous bilateral tonsil carcinoma: case presentation and review of the literature

Background

The incidence of synchronous bilateral tonsil carcinoma seems to be underreported. For adequate oncologic treatment, it is mandatory to remove all primaries to prevent recurrence or metachronic disease. The purpose of this manuscript is to provide a comprehensive review on this topic and to emphasize the need of bilateral tonsillectomy in cases of cancer of unknown primary (CUP) as well as in the case of a unilateral tonsillar carcinoma.

Material and methods

A systematic review of the literature was performed for “bilateral tonsillar neoplasm”, “synchronous cancer of the oropharynx” and “cancer of unknown primary in head and neck”.

Results

We present a clinical case with bilateral tonsillar carcinoma in initially suggested cancer of unknown primary. Clinically, both tonsillar sites were unsuspicious, but in PET/CT an ipsilateral enhancement of the tonsil area was detected. The pathological work up of bilateral tonsillectomy specimens revealed bilateral squamous cell carcinoma with HPV-type 16 positivity. The review of the literature revealed 29 cases of bilateral tonsil cancer.

Conclusion

The handling of tonsillar tissue in the frame of panendoscopy in the case of CUP is still controversial. We recommend a bilateral tonsillectomy as a routine procedure for cancer of unknown primary as well as unilateral tonsillar carcinoma. Herewith the detrimental consequences of occult metachronous contralateral tonsillar carcinoma can be prevented.

[Bradykinin-induced angioedema: Definition, pathogenesis, clinical presentation, diagnosis and therapy]

The incidence of bradykinin-induced angioedema is considerably lower than that of histamine-induced forms; however, the same is true for the clinician's knowledge of this condition. Bradykinin-induced angioedemas include hereditary angioedema (HAE), as well as acquired forms induced by drugs or antibody formation, e.g., during the course of oncologic disease. Drug-induced forms affect almost exclusively the head and neck region, and are thus important for the otorhinolaryngologist. Clear differentiation between histamine-induced angioedema (e. g., connected to allergy/urticaria) and bradykinin-induced angioedema is essential for selection of the specific treatment and may be lifesaving. Antihistamines and cortisone derivatives have no relevant effect in bradykinin induced-angioedema, whereas blood-derived C1 esterase inhibitor and bradykinin receptor 2 antagonists represent effective therapeutic options--both for acute and prophylactic treatment.

[Mucosal Melanoma of the Head and Neck]

Primary mucosal malignant melanoma of the head and neck is a rare tumor entity with poor clinical outcome. Its growth pattern is characterized by an infiltrative and local destructive behavior. So far no risk factors could be identified. There are practically no early symptoms of the disease, as intermitting nose bleeding or nasal obstruction typically occur in advanced stage. The standard of care remains radical tumor resection with adjuvant radiation in cases of close margin resection. Other therapeutic options like the use of interferon, antibodies or conventional chemotherapeutics have not demonstrated significant clinical benefit so far. Current efforts to investigate the biological and genomic characteristics of these tumors have been constrained by its low incidence. In order to better characterize this rare tumor entity and to establish effective novel targeted therapies it will be necessary to establish an interdisciplinary and multicentric task force.

Angioedema induced by cardiovascular drugs: new players join old friends

During the last years, two new cardiovascular drug classes, namely inhibitors of DPP IV or neprilysin, have been developed. In both cases, there is clinical evidence for their potential to induce angioedema as known already from blockers of the renin-angiotensin-aldosterone system (RAAS). The majority of angioedema induced by DPP IV inhibitors occurs during concomitant treatment with ACEi and is therefore likely mediated by overactivation of bradykinin type 2 receptors (B2). In striking contrast, the molecular pathways causing angioedema induced by neprilysin inhibitors, that is, sacubitril, are unclear, although a contribution of bradykinin appears likely. Nevertheless, there is no clinical evidence suggesting that inhibition of B2 might relieve the symptoms and/or prevent invasive treatment including coniotomy or tracheotomy in angioedema caused by these drugs. Therefore, the risk of angioedema should always be considered, especially in ambulatory care situations where patients have no rapid access to intensive care.

[Penetrating injuries of the head and neck region - a potentially life threatening situation]

Penetrating Injuries of the Head and Neck Region - A Potentially Life Threatening Situation Background: Cuts, stabs and gunshot wounds in the head and neck region are potentially life-threatening because of the high risk of vascular lesions. A consistent emergency management is usually based on an operative exploration of the wound with effective reconstruction of viable structures.

PATIENTS AND METHODS

Various penetrating injuries of the head and neck region are described in 11 cases with respect of age, gender, course of events of injury, type of injury, involved structures, diagnostic and operative procedures and outcome and compared with current literature and guidelines.

RESULTS

In 10 of 11 patients, in the context of an interdisciplinary emergency room management, CT angiography was performed following clinical examination. A surgical exploration and wound treatment was performed in 9 of these patients. The common carotid artery, the external carotid artery and large venous blood vessels of the neck were injured in 2 cases respectively. None of the patients deceased or suffered permanent damage.

CONCLUSION

The outcome of deep head and neck lesions with relevant vascular trauma is determined by a rapid and interdisciplinary approach. A rapid, systematic and interdisciplinary approach in specialized trauma centers has a significant role in ensuring that patients with penetrating wounds in the head and neck -region rarely die due to their serious injury or their consequences.

Repeat treatment with icatibant for multiple hereditary angioedema attacks: FAST-2 open-label study

BACKGROUND

The For Angioedema Subcutaneous Treatment (FAST)-2, a phase III, double-blind, randomized, multicenter, placebo-controlled study (ClinicalTrials.gov identifier: NCT00500656), established the efficacy and safety of single injections of icatibant, a bradykinin B₂ receptor antagonist, in the treatment of hereditary angioedema (HAE) attacks. Here, we evaluate the efficacy and safety of repeated treatment with icatibant in adult patients experiencing HAE attacks during the FAST-2 open-label extension (OLE) phase.

METHODS

Patients completing the controlled phase were eligible to participate in the OLE phase and receive open-label icatibant (30 mg subcutaneously) for the treatment of cutaneous, abdominal, and/or laryngeal HAE attack(s) severe enough to warrant treatment. Time to onset of symptom relief was calculated for each attack. Descriptive analyses (median, 95% CIs) were performed for all attacks; post hoc analyses were conducted in patients with at least five icatibant-treated attacks throughout the FAST-2 OLE phase. Safety was also monitored.

RESULTS

Fifty-four patients received icatibant for 374 attacks (176 cutaneous, 168 abdominal, and 30 laryngeal). For cutaneous and/or abdominal attacks (attacks 2-5), the median times to onset of symptom relief ranged between 2.0 and 2.5 h. For all laryngeal attacks, the median times to regression (start of improvement) of symptoms ranged between 0.3 and 4.0 h. Post hoc analyses showed that the overall median time to onset of symptom relief was 2.0 h. Overall, 89.8% of attacks resolved with a single icatibant injection. No drug-related serious adverse events were reported.

CONCLUSIONS

These findings have demonstrated the efficacy and safety of repeated icatibant treatment for HAE attacks.

[Bipedicled flap technique according to Schultz-Coulon using open approach for septal defect repair]

BACKGROUND

The successful closure of a nasal septal perforation is a surgical challenge, which applies especially to large defects with a diameter exceeding 2.0 × 2.0 cm. This retrospective study presents results using open septoplasty via a transcolumellar approach and bipedicled flaps according to Schultz-Coulon for closure.

RESULTS

In 45/50 patients the perforation was closed successfully (90%) (CI 0.82-0.98). The survey of patients showed significant improvement rates for all questioned parameters.

CONCLUSIONS

In our hands the bipedicled flap technique combined with open access to the nasal septum yields good success rates for closure and consecutive improvement of life quality, also for large defects exceeding 2.0 × 3.0 cm. The open approach provides cosmetically excellent results based on the appropriate suture techniques and is advantageous concerning intraoperative overview and suture of the mucosal flaps. Additionally it can be easily combined with an open septorhinoplasty.

[Secondary wound healing. Effective treatment concept after basal cell carcinoma resection in the central midface]

Plastic reconstruction of facial skin defects after tumor surgery is a commonly accepted principle. However, healing by secondary intention is discussed controversially. Here we describe a series of 22 patients after full thickness resection of basal cell carcinoma who underwent wound healing by secondary intention. A semipermeable membrane was used for wound dressing, which was changed on a weekly basis. No antibiotics or pain killers were necessary. Defects up to 2 cm, particularly those of concave subunits of the midface, entirely closed within 4-6 weeks, and secondary wound healing led to excellent functional and aesthetic results. Thus, secondary wound healing is a safe, effective and economic alternative to surgical reconstruction in selected facial areas.

Dendritic cell generation and CD4+ CD25high FOXP3+ regulatory t cells in human head and neck carcinoma during radio-chemotherapy

Background

Regulatory T cells (Treg) and dendritic cells (DC) play an important role in tumor immunity and immune escape. However, their interplay and the effects of anti-cancer therapy on the human immune system are largely unknown.

Methods

For DC generation, CD14⁺ monocytes were enriched by immunomagnetic selection from peripheral blood of advanced head and neck squamous cell carcinoma (HNSCC) patients and differentiated into immature DC using GM-SCF and IL-4. DC maturation was induced by addition of TNFα. The frequency of CD4⁺CD25^highF0XP3⁺ Treg in HNSCC patients was analyzed before and after radio-chemotherapy (RCT) by four-color flow cytometry.

Results

In HNSCC patients, the frequency of Treg (0.33 ± 0.06%) was significantly (p = 0.001) increased compared to healthy controls (0.11 ± 0.02%), whereas RCT had variable effects on the Treg frequency inducing its increase in some patients and decrease in others. After six days in culture, monocytes of all patients had differentiated into immature DC. However, DC maturation indicated by CD83 up-regulation (70.7 ± 5.5%) was successful only in a subgroup of patients and correlated well with lower frequencies of peripheral blood Treg in those patients.

Conclusion

The frequency of regulatory T cells is elevated in HNSCC patients and may be modulated by RCT. Monocyte-derived DC in HNSCC patients show a maturation deficiency ex vivo. Those preliminary data may have an impact on multimodality clinical trials integrating cellular immune modulation in patients with advanced HNSCC.

In vitro chemosensitivity of head and neck cancer cell lines

Background

Systemic treatment of head and neck squamous cell carcinoma (HNSCC) includes a variety of antineoplastic drugs. However, drug-resistance interferes with the effectiveness of chemotherapy. Preclinical testing models are needed in order to develop approaches to overcome chemoresistance.

Methods

Ten human cell lines were obtained from HNSCC, including one with experimentally-induced cisplatin resistance. Inhibition of cell growth by seven chemotherapeutic agents (cisplatin, carboplatin, 5- fluorouracil, methotrexate, bleomycin, vincristin, and paclitaxel) was measured using metabolic MTT-uptake assay and correlated to clinically-achievable plasma concentrations.

Results

All drugs inhibited cell growth in a concentration-dependent manner with an IC50 comparable to that achievable in vivo. However, response curves for methotrexate were unsatisfactory and for paclitaxel, the solubilizer cremophor EL was toxic. Cross-resistance was observed between cisplatin and carboplatin.

Conclusion

Chemosensitivity of HNSCC cell lines can be determined using the MTT-uptake assay. For DNA-interfering cytostatics and vinca alkaloids this is a simple and reproducible procedure. Determined in vitro chemosensitivity serves as a baseline for further experimental approaches aiming to modulate chemoresistance in HNSCC with potential clinical significance.

[Coagulation factors as potential tumour markers in patients with head and neck carcinomas?]

OBJECTIVE

Carcinomas can have influence on the coagulation system by different factors. Locally pathological changes of metabolism, neo-vascularisation, oxygenation and tissue pressure as well as locally and systemically activities of the tumor cells, are part of it. The coagulation situation in patients with head and neck carcinomata is characterized only insufficiently till now.

MATERIAL AND METHODS

In a prospective pilot study 20 male patients with squamous-cell carcinomas of the head and neck area were subjected to a detailed coagulation diagnostics pre and post therapeutically and, age and sex corrected, compared with a control group (n=37).

RESULTS

For the routine parameters PTT, Quick, TZ and INR no differences between the groups could be recognized. For the tumour patients a statistically significant increase arose for the acute phase proteins like factor I (fibrinogen), factor VIII, factor IX, von- Willebrand antigen and activity before therapy. Increased values were found also for plasmin, factor II, factor V and the thrombin-antithrombin-III-complex (TAT) whereas the values for antithrombin-III were degraded significantly. In the tumour patients the pre-therapeutical increased values for the activation marker TAT brought themselves back to normal after the tumour ablative therapy.

CONCLUSIONS

TAT could be suitable as a potential tumour marker but also for relapse tumours. To evidence this, a study of longer duration and with a larger number of patients is necessary.

[Breast cancer metastases in the head and neck region]

Breast cancer metastases to the head and neck region are very rare and therefore represent a challenge for the clinician in terms of diagnosis and therapy. Recent advances in breast cancer treatment have achieved longer median survival times in affected patients. However, at the same time, the risk of a clinical manifestation of metastasis increases. Here we present the cases of two breast cancer patients who developed filiae into the petrous portion of the temporal bone and one very rare case of metastasis to the larynx. Diagnosis, therapy and distinctive features of metastasis to the head and neck region are discussed.Secondary to long-term endocrine hormone therapy, a reduction in estrogen receptor expression occurred in all three cases. We believe that the loss of steroid receptor expression contributed to tumor resistance to endocrine therapy. Moreover, this receptor loss hindered the pathologist from confirming the diagnosis of metastases at very unusual sites.

[Emergency management of acute angioedema]

Angioedema is an oedematous swelling of the mucosa or submucosa of the skin. Acute angioedema represents a clinical emergency when the pharynx or larynx are involved and breathing of the patient is impaired. For rapid and effective treatment it is necessary to differentiate between allergic and non-allergic angioedema. Three of the five subforms of non-allergic angioedema are mediated by bradykinin: renin-angiotensin-aldosterone system (RAAS)-blocker-induced angioedema (RAE), hereditary angioedema (HAE) and acquired angioedema (AAE). Antihistamines, corticosteroids and adrenalin can be used to treat allergic angioedema but are ineffective in acute attacks of non-allergic angioedema. In these events the bradykinin-B2-receptor antagonist icatibant (in HAE, or RAE) or C1-INH concentrate (in HAE, or AAE) are therapeutic options for rapid alleviation of acute angioedema. The following article gives an overview of the diagnostics and treatment in the emergency situation of "acute angioedema", especially if swelling of the head-and-neck region is present.

Parallel high-resolution confocal Raman SEM analysis of inorganic and organic bone matrix constituents

In many multi-disciplinary fields of science, such as tissue engineering, where material and biological sciences are combined, there is a need for a tool that combines ultrastructural and chemical data analysis in a non-destructive manner at high resolution. We show that a combination of confocal Raman spectroscopy (CRS) and scanning electron microscopy (SEM) can be used for such analysis. Studies of atomic composition can be done by X-ray microanalysis in SEM, but this is only possible for atomic numbers greater than five and does not reveal molecular identity. Raman spectroscopy, however, can provide information on molecular composition and identity by detection of wavelength shifts caused by molecular vibrations. In this study, CRS-SEM revealed that early in vitro-formed bone extracellular matrix (ECM) produced by rat osteoprogenitor cells resembles mature bone chemically. We gained insight into the structure and chemical composition of the ECM, which was composed of mainly mineralized collagen type I fibres and areas of dense carbonated calcium phosphate related to the collagen fibre density, as revealed by Raman imaging of SEM samples. We found that CRS-SEM allows the study of specimens in a non-destructive manner and provides high-resolution structural and chemical information about inorganic and organic constituents by parallel measurements on the same sample.

Single chromatin fiber stretching reveals physically distinct populations of disassembly events

Eukaryotic DNA is packaged into the cell nucleus as a nucleoprotein complex, chromatin. Despite this condensed state, access to the DNA sequence must occur during gene expression and other essential genetic events. Here we employ optical tweezers stretching of reconstituted chromatin fibers to investigate the release of DNA from its protein-bound structure. Analysis of fiber length increase per unbinding event revealed discrete values of approximately 30 and approximately 60 nm. Furthermore, a loading rate analysis of the disruption forces revealed three individual energy barriers. The heights of these barriers were found to be approximately 20 k(B)T, approximately 25 k(B)T, and approximately 28 k(B)T. For subsequent stretches of the fiber it was found that events corresponding to the approximately 28 k(B)T energy barrier were significantly reduced. No correlation between energy barrier crossed and DNA length release was found. These studies clearly demonstrate that optical tweezers stretching of chromatin provides insight into the energetic penalties imposed by chromatin structure. Furthermore these studies reveal possible pathways via which chromatin may be disrupted during genetic code access.

Integration of microfluidics with a four-channel integrated optical Young interferometer immunosensor

This report describes an optical sensing hybrid system obtained by bonding a microfluidic system to an integrated optical (IO) four-channel Young interferometer (YI) chip. The microfluidic system implemented into a glass plate consists of four microchannels with cross-sectional dimensions of 200 microm x 15 microm. The microfluidic system is structured in such a way that after bonding to the IO chip, each microchannel addresses one sensing window in the four-channel YI sensor. Experimental tests show that the implementation of the microfluidics reduces the response time of the sensor from 100s, as achieved with a bulky cuvette, to 4s. Monitoring the anti-human serum albumine/human serum albumine (alpha-HSA/HSA) immunoreaction demonstrates the feasibility to use the microfluidic sensing system for immunosensing applications. In this case, a better discrimination between the bulk refractive index change and the layer formation can be made, resulting into higher accuracy and offering the prospect of being able to use the kinetics of the immunoreaction. The microfluidic sensing system shows an average phase resolution of 7 x 10(-5) x 2pi for different pairs of channels, which at the given interaction length of 4 mm corresponds to a refractive index resolution of 6 x 10(-8), being equivalent to a protein mass coverage resolution of 20 fg/mm2.

Comparison of the role of endothelin, vasopressin and angiotensin in arterial pressure regulation during sevoflurane anaesthesia in dogs

BACKGROUND

In this study we aimed to clarify the role of endothelin in arterial pressure regulation during anaesthesia with increasing concentrations of sevoflurane (1-3 MAC) and compare it with those of vasopressin and angiotensin.

METHODS

After an awake control period, on different days, six dogs underwent each of the following four interventions: sevoflurane anaesthesia alone (1-3 MAC), sevoflurane after block of either endothelin receptors using tezosentan (3 mg kg(-1) followed by 3 mg kg(-1) h(-1)), vasopressin V(1a) receptors using [d(CH(2))(5)Tyr(Me(2))]AVP (40 micro g kg(--1)) or angiotensin receptors using losartan (6 mg kg(-1) h(-1)). Plasma concentrations of endothelin, big endothelin, vasopressin and renin were measured. Effects of sevoflurane in the presence and absence of the respective receptor block were analysed and compared using analysis of variance for repeated measures (ANOVA followed by Fisher's PLSD (protected least significant difference) (P<0.05)).

RESULTS

Mean arterial pressure decreased in a dose-dependent manner with sevoflurane during all interventions. At 1 MAC, this decrease was greatest during angiotensin receptor block (mean (SEM), -41 (3) mm Hg), intermediate during vasopressin and endothelin receptor block (-31 (4) and -30 (2) mm Hg respectively), and least during sevoflurane alone (-24 (3) mm Hg). The course of systemic vascular resistance mirrored the course of arterial pressure, while cardiac output did not differ between groups. Plasma concentrations of endothelin, big endothelin and renin did not change during any intervention, whereas vasopressin concentration increased from approximately 0.5 to 40 ng litre(-1) at 3 MAC as arterial pressure decreased in all groups.

CONCLUSIONS

At 1 MAC, angiotensin attenuated the decrease in arterial pressure during sevoflurane anaesthesia more than endothelin and vasopressin. However, at higher MAC only vasopressin was specifically activated to partly compensate for the arterial pressure decrease.

Nonresonant Raman imaging of protein distribution in single human cells

A confocal Raman microscope is used to study the protein distribution inside biological cells. It is shown that high quality Raman imaging of the protein distribution can be obtained using confocal nonresonant Raman imaging (lambda(exc) = 647.1 nm). The results are shown for two different human cell types. Perpheral blood lymphocytes are used as an example of the fully maturated cells with a low level of nuclear transcription. Human eye lens epithelial cells are used as an example of cells with a high level of nuclear activity. The protein distribution in both cell types is completely different. The nuclear distribution of the protein largely varies in the peripheral blood lymphocyte cells, while proteins are more homogenously distributed over the nuclear space in the eye lens epithelial cells. The imaging time is approximately 20 min for a field of view of 10 x 10 microm(2). The size of the sampling volume is 1.4 fL using a full width at half-maximum criterion along the z axis and a 1/e(2) criterion in the xy plane. The results presented here indicate that Raman imaging is particularly of interest in the study of cellular processes, like phagocytosis, apoptosis, chromatin compaction, and cellular differentiation, which are accompanied by relatively large-scale redistributions of the materials.

Nonresonant confocal Raman imaging of DNA and protein distribution in apoptotic cells

Nonresonant confocal Raman imaging has been used to map the DNA and the protein distributions in individual single human cells. The images are obtained on an improved homebuilt confocal Raman microscope. After statistical analysis, using singular value decomposition, the Raman images are reconstructed from the spectra covering the fingerprint region. The data are obtained at a step interval of approximately 250 nm and cover a field from 8- to 15- micro m square in size. Dwell times at each pixel are between 0.5 and 2 s, depending on the nature and the state of the cell under investigation. High quality nonresonant Raman images can only be obtained under these conditions using continuous wave high laser powers between 60 and 120 mW. We will present evidence that these laser powers can still safely be used to recover the chemical distributions in fixed cells. The developed Raman imaging method is used to image directly, i.e., without prior labeling, the nucleotide condensation and the protein distribution in the so-called nuclear fragments of apoptotic HeLa cells. In the control (nonapoptotic) HeLa cells, we show, for the first time by Raman microspectroscopy, the presence of the RNA in a cell nucleus.

Scanning confocal fluorescence microscopy for single molecule analysis of nucleotide excision repair complexes

We used scanning confocal fluorescence microscopy to observe and analyze individual DNA- protein complexes formed between human nucleotide excision repair (NER) proteins and model DNA substrates. For this purpose human XPA protein was fused to EGFP, purified and shown to be functional. Binding of EGFP-labeled XPA protein to a Cy3.5-labeled DNA substrate, in the presence and absence of RPA, was assessed quantitatively by simultaneous excitation and emission detection of both fluorophores. Co-localization of Cy3.5 and EGFP signals within one diffraction limited spot indicated complexes of XPA with DNA. Measurements were performed on samples in a 1% agarose matrix in conditions that are compatible with protein activity and where reactions can be studied under equilibrium conditions. In these samples DNA alone was freely diffusing and protein-bound DNA was immobile, whereby they could be discriminated resulting in quantitative data on DNA binding. On the single molecule level approximately 10% of XPA co-localized with DNA; this increased to 32% in the presence of RPA. These results, especially the enhanced binding of XPA in the presence of RPA, are similar to those obtained in bulk experiments, validating the utility of scanning confocal fluorescence microscopy for investigating functional interactions at the single molecule level.

Integrated optical microcavities for enhanced evanescent-wave spectroscopy

The use of integrated optical microcavities (MCs) for enhanced optical spectroscopy and sensing is investigated. The MC sustains high- Q whispering-gallery modes, in which the energy of the optical field can be efficiently stored. The resulting enhanced field can be used to probe fluorescent molecules in the cladding of the MC. Enhanced fluorescence excitation with an integrated optical MC is demonstrated experimentally for what is believed to be the first time. A comparison between a MC and a straight waveguide shows that the MC may give an increase of 40 times in fluorescence excitation. Because of the ultrasmall size of the MC (15 microm in radius), the fluorescence signal may be observed from only 20 molecules in the cladding.

Influence of Ca2+ cations on low pH-induced DNA structural transitions

A confocal Raman microspectrometer was used to investigate the influence of Ca2+ cations on low pH-induced DNA structural changes. The effects of Ca2+ cations on the protonation mechanism of opening AT and changing the protonation of GC base pairs in DNA are discussed. Based on the observation that the midpoint of the transition of Watson-Crick GC base pairs to protonated GC base pairs lies at around pH 3 (analyzing the 681 cm(-1) line), measurements were carried out on calf thymus DNA at neutral pH and pH 3 in the presence of low and high concentrations of Ca2+ cations. Raman spectra show that low concentrations of Ca2+ cations partially protect DNA against protonation of cytosine (characteristic line at 1262 cm(-1)) and do not protect adenine (characteristic line at 1304 cm(-1)) and the N(7) of guanine (line at 1488 cm(-1)) against binding of H+. High Ca2+ concentrations can prevent protonation of cytosine and protonation of adenine (little disruption of AT pairs). Analyzing the line at 1488 cm(-1), which obtains most of its intensity from a guanine vibration, high salt was also found to protect the N(7) of guanine against protonation.

Sensor based on an integrated optical microcavity

A novel integrated optical sensor based on a cylindrical microcavity (MC) is proposed. A MC sustains so-called whispering-gallery modes (WGMs), in which the energy of the optical field can be efficiently stored. By monitoring the scattering intensity from the MC, one can detect minute changes in the refractive index of the WGM, for instance, as a result of analyte adsorption. Measurement of a change in refractive index of as little as 10(-4) is demonstrated experimentally. The MC-based integrated optical sensor may have a size of approximately 8mum , and it is rugged and inexpensive.

catena-poly[[(acetonitrile-N)dichlorocopper(II)]-mu-2,5-dimethylpyrazine-kappa2N:N']

In the structure of the title compound, [CuCl2(C2H3N)(C6H8N2)], each Cu2+ cation is surrounded by two 2,5-dimethylpyrazine ligands, one acetonitrile ligand and two Cl- anions within a distorted tetragonal pyramid. The acetonitrile ligand, which forms the apex of the pyramid, the Cu2+ cation and the Cl- anions are all located in general positions, whereas each of the 2,5-dimethylpyrazine ligands is located about a centre of inversion. The 2,5-dimethylpyrazine ligands connect the Cu2+ cations via mu-N:N' coordination to form chains.

Unfolding individual nucleosomes by stretching single chromatin fibers with optical tweezers

Single chromatin fibers were assembled directly in the flow cell of an optical tweezers setup. A single lambda phage DNA molecule, suspended between two polystyrene beads, was exposed to a Xenopus laevis egg extract, leading to chromatin assembly with concomitant apparent shortening of the DNA molecule. Assembly was force-dependent and could not take place at forces exceeding 10 pN. The assembled single chromatin fiber was subjected to stretching by controlled movement of one of the beads with the force generated in the molecule continuously monitored with the second bead trapped in the optical trap. The force displayed discrete, sudden drops upon fiber stretching, reflecting discrete opening events in fiber structure. These opening events were quantized at increments in fiber length of approximately 65 nm and are attributed to unwrapping of the DNA from around individual histone octamers. Repeated stretching and relaxing of the fiber in the absence of egg extract showed that the loss of histone octamers was irreversible. The forces measured for individual nucleosome disruptions are in the range of 20-40 pN, comparable to forces reported for RNA- and DNA-polymerases.