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Biomedical subjects

M Helbig

Publications and source records attributed to M Helbig.

At least 19 recordsLinked to original sources
PubMed2007

[Quality management: reduced waiting time and enhanced efficiency in a university ear, nose, and throat outpatient department].

BACKGROUND: The introduction of Diagnosis-Related Groups, which standardize payment for each clinical service, entails keeping the inpatient treatment as short as possible. Thus outpatient treatment is gaining in importance. To cope with this change, organizational and structural modifications of clinic routine are necessary. METHODS: In the ear, nose, and throat outpatient clinic of Johann Wolfgang Goethe University in Frankfurt, Germany, a hotline was established that allows patients to make appointments and get advice based on quality management guidelines according to DIN EN ISO 9001:2000. The development of this project is described here step by step, from planning to inclusion in the daily clinic routine. RESULTS: Patient visits became more effective despite increasing demand. This resulted in high satisfaction of patients and clinic personnel alike. CONCLUSION: This model may contribute considerably to coping with the increasing demand for clinic appointments and to optimal use of a clinic's human resources.

Academic Medical Centers↗
PubMed2006

Time-variant parametric estimation of transient quadratic phase couplings between heart rate components in healthy neonates.

The heart rate variability (HRV) can be taken as an indicator of the coordination of the cardio-respiratory rhythms. Bispectral analysis using a direct (fast Fourier transform based) and time-invariant approach has shown the occurrence of a quadratic phase coupling (QPC) between a low-frequency (LF: 0.1 Hz) and a high-frequency (HF: 0.4-0.6 Hz) component of the HRV during quiet sleep in healthy neonates. The low-frequency component corresponds to the Mayer-Traube-Hering waves in blood pressure and the high-frequency component to the respiratory sinus arrhythmia (RSA). Time-variant, parametric estimation of the bispectrum provides the possibility of quantifying QPC in the time course. Therefore, the aim of this work was a parametric, time-variant bispectral analysis of the neonatal HRV in the same neonates used in the direct, time-invariant approach. For the first time rhythms in the time course of QPC between the HF component and the LF component could be shown in the neonatal HRV.

Arrhythmia, Sinus↗
PubMed2006

[Quality assessment according to DIN EN ISO 9001:2000: certification in a university ENT department].

BACKGROUND: In 2003, our department inaugurated a quality management system. The certification according to DIN EN ISO 9001:2000 as required by the hospital management was achieved in August 2005. The aims were optimization of internal operating schedules and standardization of procedures according to logistic interfaces with external structures. METHODS: Since 2000, the implementation of an internal quality management system is required by German law and threatened by penalty in case of non-implementation. Beside a basic audit and optimization of all organizational procedures, all core processes were determined and the approvals checked. These aims involve both the quality of operational procedures, in and outpatient treatment, research, study and teaching and aspects of service such as quickness of scheduling and forwarding of reports as well as economic aspects and efficiency. The department of "quality management", whose main tasks are the professional guidance and the training of the quality management representatives, plays an important role. RESULTS: Realization of the new regulations and restructuring resulted in an increase in effectiveness and an improvement in operational procedures. In particular, patients and staff have benefited from the reorganized and modified sequence of operations. CONCLUSION: Implementation of a quality management system in different hospital departments is recommended.

Academic Medical Centers↗
PubMed2005

[Intraoperative endosonographic guided resection of tongue carcinoma].

BACKGROUND: Exact estimation of a tumor's size and the definition of adequate resection margins in carcinomas of the tongue are often difficult because of the tumor's extension and deep infiltration. METHODS: We have developed a method that allows intraoperative visualisation and marking of tumor margins. Intra-operative endosonography was performed on nine patients with carcinomas of the tongue using a 8-12 MHz linear array transducer. The oral cavity was flooded with normal saline solution and the transducer was immersed therein. This allowed scanning in a non-contact mode. The tumor margins were marked with a surgical suture under endosonographic monitoring. RESULTS: In the nine patients studied, the histological margins corresponded to the sonographic margins. The sonographic marking proved to be useful during the resection of the tumor and histological safety margins were respected in each case. CONCLUSIONS: This non-invasive procedure provides a quick and reliable orientation during the resection of tongue carcinoma, and a more precise and individual definition of resection margins is possible. Intraoperative non-contact use of endosonography is a promising method.

Adult↗
PubMed2004

On the spatio-temporal organisation of quadratic phase-couplings in 'tracé alternant' EEG pattern in full-term newborns.

OBJECTIVE: The time courses of quadratic phase-coupling (QPC) of electroencephalographic burst and interburst patterns of the 'trace alternant' (TA) in full-term newborns have been quantified. METHODS: Using the Gabor expansion, a fast Fourier transformation based method, biamplitude, bicoherence and phase-bicoherence time courses of both burst and interburst patterns have been determined (common average reference EEG recordings). With a frequency resolution of 0.25 Hz and a frequency grid of 1-1.5 <==> 3.5-4.5 Hz (region-of-interest), a number of 15 frequency pairs result. These pairs have been investigated. RESULTS: The burst and the interburst patterns are characterized by temporally and topographically different QPC profiles. All differences are dominant at the electrode Fp1 followed by Fp2. There is a significant difference (combined multiple and global test strategy) in the QPC characteristics between both patterns within the time period from 0.75 to 1.5 s after the pattern onset at electrode Fp1. The maximal QPC in burst patterns (especially at Fp1) can be observed during this time period. In contrast to this finding, maximal QPC in interburst patterns (at Fp1) are reached immediately after the onset and at 3 s. Summarising all findings, a QPC-rhythm of 0.1 Hz during TA can be assumed. CONCLUSIONS: It can be assumed that the QPC rhythm of the TA is generated by a pattern-spanning time-variant phase-locking process and there are indications for a possible correspondence between the QPC rhythm and vegetative rhythms. SIGNIFICANCE: This study showed that advanced, time-variant analysis methods quantifying QPC rhythms are able to add new scientific information to the understanding of nature, characteristics and significance of TA in the neonatal EEG.

Algorithms↗
PubMed2004

Prognostic impact of EBV-related LMP-1, histologic type, and environmental factors in nasopharyngeal carcinoma in a German population.

INTRODUCTION: This retrospective study addressed the possible involvement of latent Epstein-Barr virus (EBV) infection, in particular LMP-1 expression, and further exogenous factors, i.e. tobacco, alcohol and occupational hazardous substances, in nasopharyngeal carcinoma (NPC) in a German population. PATIENTS AND METHODS: From 1980 to 2000, 44 patients suffering from histologically confirmed NPC were entered into the study. 33 specimens were available for immunostaining (IHC) to analyze LMP-1 expression. Information about environmental exposures were obtained employing a detailed standardized questionnaire. RESULTS: Outcome of patients with squamous cell NPC (SC-NPC) was significant worse than that of those with non-keratinizing NPC (NK-NPC). Age and tumor size correlated with response to therapy. The group with negative conventional LMP-1 staining showed better overall survival after 5 years compared to the group with positive or marginally positive LMP-1 detection (not significant). Nevertheless, after staining by tyramid-augmented IHC (TSA-IHC), nearly all specimens with negative LMP-1-staining in conventional IHC were found to be clearly positive. All patients with SC-NPC were smokers. The distribution of smokers and non-smokers in the group of NK-NPC was balanced. Comparable to the tobacco observation, there was also a correlation between high alcohol consumption and SC-NPC. CONCLUSION: Prognosis of NPC is mainly dependent on histologic type. Prognostic impact of LMP-1 is still unclear since LMP-1 was detected in all specimens using TSA-IHC. Therefore, TSA-IHC-LMP-1 detection might be interesting for diagnostic specification and development of new therapeutic strategies in NPC.

Adaptor Proteins, Signal Transducing↗
PubMed2003

[Dynamic magnetic resonance tomography (dMRT). It's value in advanced head-neck tumors treated with radiochemotherapy].

PURPOSE: With the help of dynamic magnetic resonance tomography (dMRT) the status of tissue microcirculation can be visualized. METHODS: Dynamic MRI was performed in 13 patients with advanced, nonresectable oro- or hypopharynx carcinoma at the beginning and the end of therapy. Maximal signal intensity and exchange rate constant in the tissue of the tumor and the lymph node metastases were analyzed using a pharmacokinetic two-compartment model. RESULTS: In all six patients with clinical complete response (CR), the maximal signal intensity increased after therapy in the tissue of the primary tumor and the lymph node metastases. Furthermore, a high decrease in the parameter k(21) was associated with a better prognosis and could be observed especially after combined radiochemotherapy. CONCLUSION: Our first results indicate that contrast-enhanced dynamic MRI studies before and after radio- or combined radiochemotherapy offer important information about the changes of microcirculation in the tissue of the tumor and lymph node metastases. Furthermore, this information seems to be a promising predictor for clinical outcome of therapy.

Adult↗
PubMed2002

[Time variant bispectral analysis based on adaptive recursive Fourier transformation].

An appropriate investigation of quadratic phase couplings (QPC) in non-stationary signals requires time-variant methods of bispectral analysis. A new approach for time-variant estimation of power spectrum and bispectrum based on an adaptively, recursively estimated Fourier transform (ADFT) is presented in this paper. A reduced calculation effort and the possibility of the calculation of the bispectrum for selected frequency triples are important advantages of this method. Because of the recursive calculation, the ADFT is convenient for analysing ongoing signals. This will be demonstrated for simulated and real biomedical signals.

Electroencephalography↗
PubMed2001

Intraoperative B-mode endosonography of tongue carcinoma.

BACKGROUND: Exact estimation of a tumor's size and definition of adequate resection margins in carcinomas of the tongue are often difficult because of the tumor's extension and deep infiltration. METHODS: We developed a method that allows intraoperative visualization and marking of tumor margins: intraoperative endosonography was performed in five patients with carcinomas of the tongue with an 8- to 12-MHz linear array transducer. The oral cavity was flooded with normal saline solution, and the transducer was immersed therein. This allowed scanning in a noncontact mode. The tumor margins were marked with a surgical suture under endosonographic monitoring. RESULTS: In the five patients studied, histologic margins corresponded to sonographic margins. The sonographic marking proved to be useful during the resection of the tumor, and histologic safety margins were respected in each case. CONCLUSIONS: This noninvasive procedure provides a quick and reliable orientation during resection of tongue carcinoma, and a more precise and individual definition of resection margins is possible. Intraoperative noncontact use of endosonography is a promising method, and further studies may confirm this.

Adult↗
PubMed2001

Time-variant non-linear phase-coupling analysis of EEG burst patterns in sedated patients during electroencephalic burst suppression period.

OBJECTIVES: The quadratic phase-coupling (QPC) within burst patterns during electroencephalic burst suppression has been quantified. METHODS: It can be shown that a QPC exists between the frequency ranges 0-2.5 and 3-7.5 Hz and between the frequency ranges 0-2.5 and 8-12 Hz. By means of time-variant bicoherence analysis, a strong phase-locking between the modulating and the modulated component can be identified. The phase-locking is demonstrable within the first 250 ms after the burst onset and comes up to the maximum between 750 and 1250 ms. RESULTS: The effect is maintained over the whole first part of the burst (2 s) with a decreasing tendency after 1250 ms. All these effects cannot be found in the EEG before entering the burst suppression period (BSP). The transient coupling phenomena in the EEG bursts during BSP can be regarded as indicators for short-term interrelations between the underlying electrophysiologic processes. CONCLUSIONS: It can be suggested that the method introduced for the quantification of the sedation depth should be used.

Cerebrospinal Fluid Pressure↗
PubMed2000

Sonography of nasal tip anatomy and surgical tip refinement.

The amorphous or wide nasal tip is the most commonly encountered nasal tip deformity, but little has been done to measure the effect of standard rhinoplasty techniques on nasal tip width. In the clinical routine, nasal tip width and soft-tissue cover thickness are estimated by inspection and palpation rather than by measurement. In this study, a B-mode sonograph with a 12-MHz transducer was used in a noncontact mode to measure tip width 0.5 cm occipital to the tip defining point, distance between the alar cartilage domes, and thickness of the soft-tissue cover overlying the lower lateral cartilages. These parameters were measured 3 to 8 weeks before and 56 days to 19 months after a transdomal suture tip plasty in 18 patients. The distance between the alar cartilage domes seemed to be an important factor for tip width because interdomal distance, not soft-tissue cover thickness, correlated with tip width before surgery (correlation: 0.53). Conversely, the degree of tip refinement correlated with preoperative soft-tissue cover thickness (correlation: 0.75), but not with interdomal distance. Ultrasonic imaging of nasal soft tissues may help to assess the effect of different tip refining procedures and other soft-tissue changes after rhinoplasty.

Adult↗
PubMed1999

[Cystic space-occupying lesion of the neck soft tissues: cave echinococcosis].

The diagnosis of cystic echinococcosis (echinococcus granulosus) in an atypical location can be difficult to make and frequently can only be established by histological examination of affected tissues. Surgical excision and fine-needle aspiration biopsy usually lead to the diagnosis. Since puncture of these cysts may cause an anaphylactic reaction due to spillage of hydatid fluid and/or dissemination of infection, the use of fine-needle aspiration biopsy is controversial at present. We report on a patient with a cystic neck mass who developed an allergic reaction after diagnostic fine-needle aspiration biopsy. Cytological examination of the specimen was inconclusive. The allergic reaction led to the diagnosis of echinococcosis, which was confirmed by serological examination. We describe a possible diagnostic procedure for a cystic mass of unknown etiology. If imaging and serological tests are not conclusive, we believe that fine-needle aspiration biopsy is justified. However, this should only be performed in a setting that provides sufficient management for anaphylactic reactions.

Adult↗
PubMed1999

[The role of oncogenic human papillomaviruses in tonsillar squamous cell carcinomas with functional inactivation of the retinoblastoma protein].

In order to identify squamous cell carcinomas of the head and neck (HNSCC) with common biological and clinical features, we investigated the incidence and properties of carcinomas lacking retinoblastoma protein (pR6) cell cycle control. Of 208 HNSCC investigated, 23 (11%) showed a lack of pRb expression. The majority of these tumors (65%) were tonsillar carcinomas. The pRb-negative tonsillar tumors were all stage IV, had metastasized to lymph nodes at the time of diagnosis and were in general poorly differentiated or undifferentiated. Very significantly, the pRb-negative phenotype was strongly associated with the presence of oncogenic human papilloma viruses, implying a viral etiology and functional inactivation of pRb by the viral E7 oncoprotein. Despite the very adverse histopathological factors, patients with pRb-negative tonsillar carcinomas had a better clinical outcome, which was consistent with a uniform favorable responsiveness of these tumors to postoperative radiation therapy.

Carcinoma, Squamous Cell↗
PubMed1998

Etiological involvement of oncogenic human papillomavirus in tonsillar squamous cell carcinomas lacking retinoblastoma cell cycle control.

Two hundred eight primary squamous cell carcinomas of the head and neck have been analyzed with respect to the presence of the retinoblastoma tumor suppressor protein, pRb. Of these, 23 tumors (11%) that preferentially localized to the tonsils revealed complete absence or dramatic reduction in the amount of pRb. Other cell cycle components, cyclin D1 and p16INK4A, which are intimately related to pRb through an autoregulatory loop, were also dramatically decreased or overexpressed, respectively, in these pRb-defective tumors. On the other hand, the majority of the pRb-defective tumors contained the wild-type p53 gene. No evidence was found for genetic defects at the Rb locus in these tumors. Very significantly, in 11 of 12 pRb-defective tonsillar tumors, but in none of 9 pRb-positive tonsillar tumors (P < 10[-7]), DNA of oncogenic human papillomavirus types was identified, providing a strong indication for a human papillomavirus-associated etiology of these tumors and suggesting the functional inactivation of the pRb protein by the viral E7 gene product. In comparison to all head and neck squamous cell carcinomas studied, the pRb-defective tonsillar tumors were in general more poorly differentiated (P = 0.0059), and they were all metastatic at the time of resection. Of particular clinical interest, despite these adverse histopathological factors, the clinical outcome for these patients was relatively favorable, strongly implying that the pRb-defective tumors responded uniformly well toward postoperative radiation therapy.

Carcinoma, Squamous Cell↗
PubMed1998

[Power Doppler and B-mode sonography of nasal mucosa].

Anatomy and perfusion of the nasal septum and inferior turbinate mucosa can be visualized with B-mode and power-Doppler ultrasound. The transducer is placed externally on the nasal ala parallel to the pyriform crest and directed towards the head of the inferior turbinate of the opposite side. An individually prepared dental splint keeps the transducer in position and allows assessment of dynamic changes in mucosal swelling and perfusion. Perfusion changes are evaluated by computerized quantification of power-Doppler color pixels. Coupling of ultrasound across the nasal lumen is achieved by introducing gel into one nasal vestibule and flooding the anterior nasal cavity of the side to be visualized with isotonic aqueous solutions. Perfusion could be visualized in 23 of 30 subjects, while B-mode sonographic anatomy was visualized in 16 subjects. The effect of isotonic saline solution (10 healthy subjects), naphazoline (10 patients with chronic nasal obstruction) and allergen extracts (10 patients with allergic rhinitis) on mucosal perfusion and swelling was studied. Isotonic saline solution induced a maximum drop in power-Doppler color pixel density by 10% and a maximum increase by 27%, but no change was seen in mucosal swelling. Naphazoline induced a 10-57% decrease in power-Doppler pixel density and decongestion of the inferior turbinate and septum mucosa by 17-43% and 4-27%, respectively. Allergen extracts induced an increase in power-Doppler color pixel density by 24-181% and an increase in mucosal thickness by 4-31%. These preliminary results encourage further studies of nasal mucosal perfusion changes using power-Doppler sonography after pharmacologic and allergen provocations.

Adult↗
PubMed1998

[Chronic laryngeal edema as a late reaction to radiochemotherapy].

In addition to mucositis and myelotoxicity as well known early reactions after radiotherapy or radiochemotherapy in advanced head and neck tumors, late toxicity following treatment is an often underestimated problem. Between 1992 and 1995, 68 patients with advanced oro- and hypopharyngeal tumors were treated primarily with accelerated concomitant boost radiochemotherapy (total dose irradiations of 66 Gy and carboplatin as chemotherapy). Ninety-three per cent of the patients had stage IV disease according to the UICC-TNM classification. Monitoring of follow-up included late toxicity with special attention given to laryngeal edema. In 37 patients (54%) edema of the larynx as a late complication of radiochemotherapy was observed by clinical investigation and CT scan. The median onset of laryngeal edema was found 121 days after completion of therapy, with a median time of observation of 250 days. Observations in these patients demonstrated the chronic character of this edema. An increase in the laryngeal edema in 5 cases resulted in tracheostomy. Laryngeal edema in 10 patients was associated with recurrence of tumor. These results show that after xerostomia laryngeal edema is the main late toxicity in the head and neck after radiochemotherapy and should lead to further investigations to exclude possible recurrent tumor.

Adult↗