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Biomedical subjects

K Sommer

Publications and source records attributed to K Sommer.

At least 19 recordsLinked to original sources
PubMed2006

[Squamous cell carcinoma of the conjunctiva with orbital invasion: orbital exenteration or minimally invasive procedure?].

BACKGROUND: Here we present a case of a female patient with squamous cell carcinoma with orbital invasion who insisted on a globe-sparing excisional biopsy rather than a more invasive procedure. CASE: A 48-year-old patient presented with a conjunctival tumor at the medial canthus of the right eye. The visual acuity in this eye was 1.0. MRI showed a 25 mm x 12 mm tumor, with orbital invasion, no metastasis, but on CT scan damage of the lamina papyracea was suspected. Histology of a punch biopsy confirmed a moderately differentiated, squamous cell carcinoma. As requested by the patient, simple tumor excision with a 5-mm safety margin, reconstruction of the lower fornix with amniotic membrane, and adjuvant mitomycin C therapy were performed. Intraoperatively the medial orbital wall was found to be intact. No local or systemic recurrence has occurred 3.5 years postoperatively. The patient's VA is still 1.0; no visual field defects are detectable, and there are only minor upper lid levator restriction and diplopia in maximum upgaze. CONCLUSION: In view of this case the choice of surgical treatment for malignant tumors of the conjunctiva with orbital invasion - between exenteration or a minimally invasive procedure - should be carefully discussed with the patient. A follow-up of 5 years is strongly recommended.

Carcinoma, Squamous Cell↗
PubMed2006

Prolonged high-pressure treatments in mammalian skeletal muscle result in loss of functional sodium channels and altered calcium channel kinetics.

Activation and inactivation of ion channels involve volume changes from conformational rearrangements of channel proteins. These volume changes are highly susceptible to changes in ambient pressure. Depending on the pressure level, channel function may be irreversibly altered by pressure. The corresponding structural changes persist through the post-decompression phase. High-pressure applications are a useful tool to evaluate the pressure dependence as well as pressure limits for reversibility of such alterations. Mammalian cells are only able to tolerate much lower pressures than microorganisms. Although some limits for pressure tolerance in mammalian cells have been evaluated, the mechanisms of pressure-induced alteration of membrane physiology, in particular of channel function, are unknown. To address this question, we recorded fast inward sodium (I(Na)) and slowly activating L-type calcium (I(Ca)) currents in single mammalian muscle fibers in the post-decompression phase after a prolonged 3-h, high-pressure treatment of up to 20 MPa. I(Na) and I(Ca) peak amplitudes were markedly reduced after pressure treatment at 20 MPa. This was not from a general breakdown of membrane integrity as judged from in situ high-pressure fluorescence microscopy. Membrane integrity was preserved even for pressures as high as 35 MPa at least for pressure applications of shorter durations. Therefore, the underlying mechanisms for the observed amplitude reductions have to be determined from the activation (time-to-peak [TTP]) and inactivation (tau(dec)) kinetics of I(Na) and I(Ca). No major changes in I(Na) kinetics, but marked increases, both in TTP and tau(dec) for I(Ca), were detected after 20 MPa. The apparent molecular volume changes (activation volumes) deltaV(double dagger) for the pressure-dependent irreversible alteration of channel gating approached zero for Na+ channels. For Ca2+ channels, deltaV(double dagger) was very large, with approx 2.5-fold greater values for channel activation than inactivation (approx 210 A3). We conclude, that in skeletal muscle, high pressure differentially and irreversibly affects the gating properties and the density of functional Na+ and Ca2+ channels. Based on these results, a model of high pressure-induced alterations to the channel conformation is proposed.

Animals↗
PubMed2006

High energy probe for detecting lymph node metastases with 18F-FDG in patients with head and neck cancer.

AIM: of this study was to validate a newly developed high energy probe (positron emission probe, PEP) optimised for localising PET tracers in vivo. PATIENTS AND METHODS: Physical investigations included determination of full width at half maximum (FWHM) values at a distance of 1 cm and angular resolution using different point sources. Values obtained with the new probe were compared to those of a conventional gamma probe (CGP). Additionally, PET studies were performed in 36 patients (6 women, 30 men) with proven head and neck cancer and suspected lymph node metastases (Axis, Marconi/Philips) after administering 250-320 MBq (18)F-FDG. Subsequent to PET investigations (18)F-FDG uptake in cervical regions was measured using the PEP. PEP investigations were carried out bilaterally in 5 lymph node (LN) levels (Robbins' classification of the neck). Results of probe studies were correlated with visual and semiquantitative PET evaluations, US and histological findings. RESULTS: FWHM of the new probe was 7 mm (CGP 22 mm) at 662 keV ((137)Cs) and angular resolution resulted in 8 degrees (CGP 60 degrees ). In 29 out of 36 patients LN metastases were suspected due to ultrasound investigations. After neck dissection, histology confirmed LN metastases in 21 patients. Sensitivity (sens.) of US amounted to 95% and specificity to 40%. In 18/21 patients LN metastases were detected by PET (sens. 86%). PET scans failed to diagnose the LN status correctly in 6/36 patients (accuracy 83%). Employing the PEP probe in 20/21 patients LN metastases were identified (sens. 95%), and LN status was determined accurately in 29/36 patients (accuracy 81%). Tumour/background ratios of PEP measurement and results of semiquantitative PET analyses were comparable. CONCLUSIONS: PEP measurement is a promising method for preoperative planning of the extent of neck dissection in patients with head and neck cancer and further for radioguided localising PET tracer accumulation during surgery.

Adult↗
PubMed2005

[Salivary gland carcinomas. 1. Epidemiology, etiology, malignancy criteria, prognostic parameters and classification].

Salivary gland carcinomas comprise a rare group of malignant tumors which are difficult to diagnose and treat due to their histopathologic diversity, variable clinical course and anatomic location, particularly with respect to the facial nerve. The present paper summarizes important features of these tumors, including recent advances in their management, i.e., diagnosis, surgery of the primary tumor, neck dissection, radiation therapy, and updates risk factors, criteria of malignancy, and prognostic variables, taking into account the relevant literature. Additionally, the present paper highlights briefly the survival rates of patients suffering from salivary gland carcinomas. The present overview is divided into two parts: the first is focused on epidemiology, etiology, criteria of malignancy, prognostic factors, and tumor classification, while part II discusses the diagnosis and therapy of salivary gland carcinomas.

Carcinoma↗
PubMed2005

[Salivary gland carcinomas Part II. Diagnosis and therapy].

Salivary gland carcinomas comprise a rare group of malignant tumors which are difficult to diagnose and treat due to their histopathologic diversity, variable clinical course and anatomic location, particularly with respect to the facial nerve. The present paper summarizes important features of these tumors, including recent advances in their management, i.e., diagnosis, surgery of the primary tumor, neck dissection, radiation therapy, and updates risk factors, criteria of malignancy, and prognostic variables, taking into account the relevant literature. Additionally, the present paper highlights briefly the survival rates of patients suffering from salivary gland carcinomas. The present overview is divided into two parts: the first is focused on epidemiology, etiology, criteria of malignancy, prognostic factors, and tumor classification, while part II discusses the diagnosis and therapy of salivary gland carcinomas.

Humans↗
PubMed2004

Characterisation and differentiation of pathogenic and non-pathogenic Acanthamoeba strains by their protein and antigen profiles.

Free-living amoebae of the genus Acanthamoeba are the causative agents of Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis. Acanthamoebae occur ubiquitously in the environment and are thus a constant cause of antigenic stimulation. In a previous study we have shown that compared to control sera, AK patients exhibit markedly lower immunoreactivities to whole cell antigen of Acanthamoeba spp. As the pathogenicity of acanthamoebae primarily relies on the excretion of proteins, it was the aim of the present study to investigate the immunoreactivity of metabolic antigen from different Acanthamoeba strains of varying pathogenicity. Three Acanthamoeba strains, one highly pathogenic, one non-pathogenic but thermophilic and one non-thermophilic non-pathogenic, were used for antigen extraction. The antigen was harvested before and after contact with human cells and all strains were tested with AK sera and with sera from healthy individuals. It was shown that the somatic protein profiles of the Acanthamoeba strains correlated to the morphological groups, and that within morphological group II-the group associated with AK-the profiles of the metabolic antigens correlated to strain pathogenicity. Moreover, it was shown that the control sera showed markedly higher immunoreactivities than the sera of the AK patients and that this immunoreactivity was generally higher to the non-pathogenic strains than to the pathogenic strain. Altogether our results once again raise the question of whether there is an immunological predisposition in AK. To our knowledge this is the first study on the immunoreactivity of metabolic antigen of acanthamoebae.

Acanthamoeba↗
PubMed2004

High pressure microscopy--a powerful tool for monitoring cells and macromolecules under high hydrostatic pressure.

A high pressure chamber, which withstands a pressure up to 300 MPa has been developed. The so-called HPDS (Hartmann, Pfeifer, Dornheim, Sommer) High Pressure Cell in combination with an inverted microscope and an analysis system allows brilliant microscopic colour pictures with an optical resolution better than 0.56 microm. The pressure chamber allows the in situ observation of dynamic changes of microscopic structures in bright field, phase contrast and fluorescence microscopy. This publication should demonstrate the capabilities of the system using results of experiments with two types of Spirogyra algae. The pictures have shown significant variations of the chloroplasma and the cell wall membrane at pressures of up to 120 MPa. The new system provides a simple way to perform microscopic analyses at pressures of up to 300 MPa.

Cell Membrane↗
PubMed2002

Effects of Porphyromonas gingivalis on the activation of mouse macrophages by lipopolysaccharide.

Porphyromonas gingivalis (PG) is a micro-organism that is suggested to play an etiologic role in acute and chronic periodontitis. The present study was undertaken to evaluate the question whether PG is capable of inducing interleukin (IL)-1beta, IL-6, macrophage inflammatory protein (MIP)-2, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production in macrophages. Furthermore, the effect of PG on the activation of macrophages by Escherichia coli-lipopolysaccharide (LPS) was studied. The cytokines were analyzed by detection of specific mRNA. The mRNA was amplified by RT-PCR and semi-quantitatively analyzed by high performance liquid chromatography and densitometrically, respectively. These studies demonstrate that LPS was more active than PG in inducing mRNA expression of IL-1beta, IL-6, MIP-2 and GM-CSF. Moreover, PG reduced the mRNA expression of the macrophages stimulated with LPS, especially the IL-1beta and IL-6 mRNA expression was decreased.

Animals↗
PubMed2001

[Transplants from the shoulder-back region].

BACKGROUND: In spacious or multilayered tissue losses and cases of multiple locations of defects, a large amount of tissue with different components such as skin, fatty tissue, and muscle is required for proper reconstruction. A donor area which can meet these demands is the shoulder-back region with the subscapular vessel, which arises from the axillary artery. PATIENTS AND METHODS: We report our clinical experience with 12 patients in whom we reconstructed defects with transplants from this region. RESULTS: Our anatomic investigation and measurements provided proof of a constant anatomy of the vessels with a length of the vascular pedicle and a vascular diameter suitable for microvascular anastomosis. Based on our clinical experience, the scapular, parascapular, and latissmus dorsi muscle transplants are very suitable for the reconstruction of very large superficial defects or for the augmentation of multilayered defects of the upper aerodigestive tract. CONCLUSIONS: A main advantage of the transplants from the shoulder and back region is the possibility of combining several transplants with a wide variety of tissue combinations with one vascular pedicle for a single-step reconstruction of multiple defects of the oral cavity and the pharynx.

Anastomosis, Surgical↗
PubMed2001

[Lymph node metastasis in head-neck tumors].

BACKGROUND: One of the most important criteria of malignancy of head and neck cancer are the cervical lymph metastases. Being significant for the therapeutical plan is how tumor depending parameters like T-stage, degree of differentiation and tumor localisation will influence the N-stage and therefore the extension of neck dissection. METHOD: To evaluate the pattern of formations of metastases and the success of therapy a retrospective study was performed on 405 patients with carcinoma of the oral cavity (n = 47), the oropharynx (n = 117), the hypopharynx (n = 47) and the larynx (n = 193). RESULTS: By the time of surgery carcinoma of the hypopharynx were most frequently accompanied by cervical metastases (80%), followed by carcinoma of the oropharynx (70%), the oral cavity (52%) and the larynx (26%). Occurrence and extension of regional lymph node metastases correlated well with T-stages and degree of differentiation. After surgical therapy locoregional recurrence could be observed in 5.2% of the patients. Five-year-survival rate was reduced to 50% on patients with positive lymph nodes. The different tumour sites showed preferred patterns of metastatic spread, without complete avoidance of certain levels. CONCLUSION: For the decision on indication and extent of neck dissection the preoperative diagnostic (ultrasound, CT-scan, MRI), localisation of tumour, T-stage, degree of differentiation and the knowledge of typical metastatic spread must be considered.

Carcinoma, Squamous Cell↗
PubMed2001

A preclinical model for experimental chemotherapy of human head and neck cancer.

We developed a mouse model in a representative human derived head and neck cancer cell line for preclinical studies to evaluate antitumor response, tumor-free survival and host toxicity of alkylating agents, antimetabolites, platinum analogs and taxanes alone or in combination. Ninety athymic NMRI mice were inoculated with human derived oral squamous cell carcinoma cells growing on the hind paw to an average volume of 180 +/- 80 mm3. Animals were stratified according to tumor volume into 10 groups (n=6-10) and treated with ifosfamide (65 mg/kg b.w.), docetaxel (24 mg/kg b.w.), cisplatin (2 mg/kg b.w.), carboplatin (6 or 10 mg/kg b.w.), methotrexate (1 mg/kg b.w.), and fluorouracil (15 mg/kg b.w.) intravenously in single agent or combination (ifosfamide plus docetaxel or ifosfamide plus carboplatin) treatment schedules or controls. Tumor volume was measured 3 times per week for 60 days. The average tumor volume, the overall survival time and the response rates (CR, PR) of the treated animals were compared with the data obtained from untreated controls and statistically evaluated. Untreated tumors showed rapid and exponential tumor growth. Single agent therapies with ifosfamide, cisplatinum, and docetaxel lead to significant tumor regression and improved overall survival. Low dose carboplatin monotherapy induced significant tumor growth delay, but not significant tumor regression. Most impressive tumor-free survival was achieved by combination treatment with ifosfamide and docetaxel. This preclinical study demonstrates an animal model capable of differentiating various chemotherapy regimens.

Animals↗
PubMed1998

[Topographic anatomic study of cells transplanted from the groin region].

We performed 25 fresh cadaver dissections to describe the anatomy of the superficial and deep circumflex iliac artery and the superficial inferior epigastric artery how they can be used as donor vessels for the free transfer of groin flaps and for living iliac bone. With the injection of ink the capillary region of these vessels in the bone (iliac crest), the muscle (internal oblique muscle) and skin (groin and thigh) was stained. The superficial and deep circumflex iliac artery are the main supply vessels of the groin and thigh, they can be found in 96% and 100% of the cases. The venous drainage of this region follows from a superficial (superficial circumflex iliac vein) and a deep venous system (Vv. comitantes accompanying the arterial branches). Both venous systems can always be found. The superficial circumflex iliac artery only supplies the skin and is the main donor vessel for skin and soft tissue transplants. The deep circumflex iliac artery supplies the pelvic bone, the internal oblique muscle and a small constant area of skin above the iliac crest. Bone, bone-muscle and bone-muscle and skin transplants can be obtained with this donor vessels. To enlarge the skin area the two arterial branches can be combined in one transplant. With an average vessel diameter of 1.5 mm (superficial circumflex iliac artery) and 3 mm (deep circumflex iliac artery) both vessels can very well be used for microvascular transplantation. These different tissues (muscle, bone, skin) can be obtained in adequate size and form struct composite defects in the upper aerodigestive tract.

Capillaries↗
PubMed1998

[Esophageal scintigraphy of Zenker's diverticula before and after diverticulotomy].

AIM: The filling and evacuation of Zenker's diverticula were scintigraphically examined before and after operation to quantify their functional relevance. These results were correlated with the symptoms of the patients and the findings of the barium swallow x-ray examination using cineradiography. METHODS: Sequential and static esophageal scintigraphies were performed in 17 patients with Zenker's diverticulum before and after laser surgical diverticulotomy. We used a gamma camera system in 45 degrees LAO-position after application of 15 ml of tea which was marked with 99mTc-DTPA. Filling and evacuation of the diverticulum were expressed in proportion to the administered activity. Relative volumes of the diverticula were obtained from cineradiography by using the height of the neighbouring cervical vertebra, and the clinical symptoms were divided into 4 groups. RESULTS: Zenker's diverticula could be verified visually and quantitatively by scintigraphy. The precise temporal course of the reduction of activity in the diverticulum was exactly determined. The scintigraphic retentions correlated with the x-ray volumes with a coefficient ranging from 0.55 to 0.85. Clinical symptoms also were not very closely related to scintigraphic and x-ray findings, respectively. CONCLUSION: The esophageal scintigraphy allows quantification of the filling and evacuation of Zenker's diverticula, thus it is suitable for objectivization of the functional relevance of the diverticula. That's why the esophageal scintigraphy should be taken to the diagnosis of diverticula in addition to the clinic and the x-ray examinations. The method is especially useful to evaluate the results after diverticulotomy.

Aged↗
PubMed1997

[Topographic-anatomic study of tissue transplants of the inguinal region].

We performed 25 fresh cadaver dissections to describe the anatomy of the superficial and deep circumflex iliac artery and the superficial inferior epigastric artery to determine how they could least to used as donor vessels for the free transfer of groin flaps and living iliac bone. With injection of ink the capillary region of these vessels was stained in (iliac crest) bone, the internal oblique muscle and skin of the groin and thigh. The superficial and deep circumflex iliac artery were shown to be the main supply vessels of the groin and thigh and could be found in 96%-100% of cases. The venous drainage of this region followed from a superficial system (superficial circumflex iliac veins) and a deep venous system (Vv. comitantes accompanying arterial branches). Both venous systems could always be found. The superficial circumflex iliac artery was shown to only supply the skin and was the main donor vessel to the skin and soft tissue transplants. The deep circumflex iliac artery supplied the pelvic bone, the internal oblique muscle and a small constant area of skin above the iliac crest. Bone, muscle and bone, muscle and skin transplants could be obtained with this donor vessel, with enlargement of the skin area possible by combining two arterial branches combined in one transplant. With an average vessel diameter of 1.5 mm (superficial circumflex iliac artery) and 3 mm (deep circumflex iliac artery) both vessels could be used satisfactorily for microvascular transplantation. Different tissues including muscle, bone and skin could be obtained in adequate amounts to replace composite defects in the upper aerodigestive tract.

Arteries↗
PubMed1997

[Clinical comparison between radial and lateral forearm flap].

BACKGROUND: Free fasciocutaneous flap transplantation is a versatile method for soft tissue reconstruction. This clinical study points out differences between the radial forearm flap and the lateral arm flap. METHODS: We used the radial forearm flap in 36 patients following tumor ablation and in 11 patients we used the lateral arm flap for soft tissue reconstruction. We studied the arterial and venous vessel calibers of the flaps, the vessel pedicle length, and the size of the skin paddle. Motor and sensory function tests of the upper/ lower arm and hand were performed after surgery. Recipient and donor site morbidity was noted. RESULTS: Compared to the forearm flap the lateral arm flap is bulky (1-5 cm vs. 0.5-1.5 cm), its vessel calibers are smaller (Art.: 1.4 vs. 1.8 mm, Ven.: 1.8 vs. 2.0 mm), flap size and maximum vessel pedicle length (10 vs. 12 cm) are equal. Raising the lateral arm flap is more demanding and needs more time due to the deep location of the vessel pedicle and the accompanying radial nerve within the intermuscular septum. On the other hand the lateral arm flap is advantageous because of primary wound closure of the donor site. The donor site of the forearm flap had to be covered with skin graft in all cases. We found sensory deficits of the proximal lower arm in 50% after dissection of the lateral arm flap and in 14% on the distal lower arm and thumb joint after dissection of the radial forearm flap. CONCLUSIONS: Both transplants are fasciocutaneous and optional innervated, they offer a constant anatomy and can be harvested simultaneously without interference to the head and neck team. Because of the specific characteristics of these flaps we prefer the radial forearm flap for soft tissue reconstruction. We use the lateral upper arm flap, if a forearm flap cannot be harvested, for head or neck augmentation and for reconstruction of large and deep defects.

Forearm↗