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Biomedical subjects

G Grevers

Publications and source records attributed to G Grevers.

At least 163 records · Page 9Linked to original sources
PubMed1988

[Do arteriovenous anastomoses of the olfactory mucosa exist? A light and transmission electron microscopy study in the rabbit].

Arteriovenous anastomoses were first mentioned more than 250 years ago. Since the original description, these peculiar vascular structures have been detected in almost every organ and tissue. In respect of the head and neck area, arteriovenous anastomoses have been mainly observed in the nasal mucosa of either humans or different animals and in the rabbit ear; the latter offers a unique chance for in-vivo studies using the ear chamber technique. Nevertheless, the existence of arteriovenous anastomoses in the nasal mucosa has often been denied. In the present study, we examined the endonasal vascular system of the rabbit by means of light- and transmission electron microscopy. No evidence for the existence of arteriovenous anastomoses could be found in the respiratory part of the nasal mucosa whereas in the deeper layers of the olfactory mucosa several vascular structures could be encountered that were similar to the glomerula digitalia of fingertips. It is emphasised that these vessels must be regarded as true arteriovenous anatomoses which might play a potential role in endonasal thermoregulation.

Animals↗
PubMed1988

[The angioarchitecture of the septal mucosa. Experimental studies of the rabbit].

Histological and transmission-electron microscopical studies alone cannot answer all questions regarding the microcirculation of the nasal mucosa. In the present study additional morphological techniques were used to demonstrate the course of the different parts of this peculiar vascular network. Using the "injection technique", the course of every single vessel of the nasal septum could be shown, but the character or size of these vascular structures was not easy to identify. Scanning electron microscopic investigations were able to verify vascular junctions of all sizes as well as intraluminal aspects of different vessels and the relations between all parts of this endonasal circulatory system. Lower magnifications also showed the tissue arrangement in the nasal septum. In higher magnifications vessels of arterial or venous character could be identified by distinct morphological features. Additional studies were carried out using vascular corrosion casts. On studying these structures, the entire course of the different parts of the endonasal vascular system could be observed. In addition, the arrangement of the different capillary networks of the nasal system, mentioned by several earlier investigators, could be demonstrated without doubt. This technique also allowed to distinguish between arteries and veins by the appearance of their endothelial cell nuclei. Summing up our findings it can be pointed out that all techniques used in this study are useful to understand the complicated angioarchitecture of the nasal mucosa. This evaluation may also be regarded as an extension of our earlier histological and ultrastructural investigations in this field.

Animals↗
PubMed1988

[Computerized tomography imaging of choanal atresia].

Choanal atresia is a rare malformation of the nose. If it occurs bilaterally, it may cause life-threatening complications shortly after birth. The disease is mainly diagnosed clinically. Only few cases have been presented and documented by means of radiologic procedures. In particular, CT presentation of this malformation has to our knowledge not been published to date.

Choanal Atresia↗
PubMed1987

Fenestrated endothelia in vessels of the nasal mucosa. An electron-microscopic study in the rabbit.

The ultrastructure of the vessels in the normal respiratory and olfactory mucosa of the nasal septum was studied in 15 adult rabbits. Capillaries with continuous and fenestrated endothelia could be observed in both tissues. In the respiratory part, many of the fenestrated capillaries were located subepithelially with their fenestrations facing the adjacent epithelium. Fenestrated capillaries of the olfactory mucosa were found mainly in the deeper parts of the tunica propria and usually revealed only a small number of fenestrations in their endothelial lining. It was also demonstrated that muscularized veins sometimes displayed fenestrated areas in their attenuated endothelia. These results are discussed and compared with the appropriate literature. Our results confirm that there is a link between the morphological peculiarities of the vascular wall and the functional behaviour of the nasal mucosa. These findings also emphasize that endothelial fenestrations seem to be characteristic for a certain segment of the microcirculatory system rather than for a distinct type of capillary vessel.

Animals↗
PubMed1987

[Bilateral carotid artery aneurysms in extensive cancer of the base of the tongue. A rare differential diagnosis in cervical swellings].

Enlarged cervical lymph nodes are a common feature in advanced head and neck cancer. In the present paper the case of a 58 year old male patient is reported, who was suffering from a huge carcinoma of the base of tongue. He also complained of bilateral cervical swellings, which were regarded as enlarged, metastatic lymph nodes prior to operation. When performing a bilateral, elective neck dissection, the swellings appeared as aneurysms of the extracranial part of the internal carotid artery. Aneurysms of the supraaortic branches are very rare and mainly located in the subclavian or axillary arteries. Only a few cases of bilateral aneurysms of the internal carotid artery have been described in the literature so far. Nevertheless, this peculiar morphological feature must be considered in the differential diagnosis of bilateral enlarged lymph nodes in head and neck cancer patients.

Aneurysm↗
PubMed1987

[Morphology of the vascular endothelium of the nasal mucosa].

In the nasal mucosa capillaries with fenestrated and continuous endothelium have been described. Fenestrated capillaries are distributed all over the tunica propria. They are increasing in number subepithelially and close to the nasal glands. Particularly subepithelially the endothelial fenestrations are facing the epithelium. This interesting, morphological feature has already been described as "polar differentiation" in capillaries of other tissues and has been interpreted as a functional differentiation. The same observations could be made in muscularised veins of the nasal mucosa. Only a few fenestrations could be detected in the endothelium of these vessels, but they were all facing the adjacent epithelium. The results indicate that the morphological peculiarities of the vascular endothelium of the nasal blood vessels are transient specialisations of this particular type of cells due to different physiological needs.

Animals↗
PubMed1987

[Cavernous tissue of the nasal mucosa].

The "cavernous" tissue of the nasal mucosa possesses a key function for different physiological and pathological conditions. In the present study we report about our own examinations on the "cavernous" tissue of the rabbit nasal mucosa. The specimen (nasal septum and anterior concha) were fixated by vascular perfusion via the carotid arteries, carefully excised and prepared for light and electron microscopy. Our observations indicate that the tunica propria of the nasal mucosa is covered by large, sinusoidal veins. Most of these vessels possess a rather thin vasvular wall. Some vessels, however, could be identified that had at first been regarded as arteries. A closer inspection, however, revealed the venous character of these muscularised vessels, which may correspond to the so called "Drosselvenen" described by Körner 50 years ago. These veins are supposed to possess a particular anatomical structure in their vascular wall called "sphincter", "muscular thickening", "cushion", or "muscular bolster" by various authors--which enables them to ease or to prevent the loss of fluid from the cavernous tissue. All our morphological findings as well as the functional significance of these peculiar structures are compared and discussed with the appropriate literature.

Animals↗
PubMed1987

[Vascular reaction in tumors in the area of the head and neck].

The vascular system possesses a variety of possibilities to respond to noxious events. Particularly the "morphological reaction" can first be observed in ultrastructural changes of the endothelial cell. In the present study we report on endothelial cell reactions in various carcinomas of the head and neck (carcinoma of the auricle, carcinoma of the maxilla). It is shown that the endothelial cell develops cytoplasmatic processes projecting into the vascular lumen. Occasionally cell edemas can be observed. The use of the scanning electron microscope allows to visualize three-dimensional aspects of the excised specimen. Tumor cells, endothelial cells and erythrocytes are obviously mixed, so that a regular vascular lumen can be found within the tumor tissue only occasionally. The results are compared and discussed, basing on available references.

Carcinoma, Squamous Cell↗
PubMed1987

[Diagnostic value of nuclear magnetic resonance tomography in space occupying lesions of the pharynx].

The diagnostic value of CT in tumours of the pharynx is limited due to the reduced soft tissue contrast of this method. In the present study we report on our own experience with MR imaging of this area. We could demonstrate that MR possesses an increasing importance in the diagnosis of tumours of the head and neck. This is mainly due to the better soft tissue contrast which can even be improved by using the paramagnetic contrast medium Gd-DTPA in certain cases.

Gadolinium↗
PubMed1987

[Squamous cell carcinoma of the scalp and non-Hodgkin's lymphoma].

This is a case report on a 70-year old male patient with a huge ulcerative squamous cell carcinoma of the scalp as well as numerous palpable lymph nodes in the neck. Tumour extirpation and bilateral conservative neck dissection were performed. Histological examination of the excised lymph nodes did not reveal a metastatic infiltration but an additional neoplasm -- a low-grade malignant lymphoma (lymphoplasmocytic immunocytoma).

Aged↗
PubMed1986

[Ultrastructure of the terminal vessels in squamous cell carcinoma of the human external ear. A transmission electron microscopy study].

Electron microscopic findings of vascular fine structure of the squamous cell carcinoma of the human auricle are reported. According to morphological criteria, the tissue was divided into three areas: non-infiltrated zone, transitional zone and centre of the tumor. In the non-infiltrated zone the vessels reveal the pattern of normal vessels of the skin. In the transitional zone endothelial cells bearing all signs of newly formed vessels can be detected as well as endothelial cells that show structural characteristics of severe cellular damage. In the tumour centre itself vessels are found with fenestrations and even true endothelial gaps. Interstitially located RBCs imitate the former outline of the vascular lumen. The observations are discussed and compared with the relevant literature.

Aged↗
PubMed1986

[Unusual location of a granular cell myoblastoma (Abrikosov tumor)].

A case of an unusual location of a granular cell myoblastoma is reported. This tumour is considered to be of neurogenic origin and has been found in different areas of the head and neck. A profound description of the histologic features is provided as well as a remark on the differential diagnosis and a review of the appropriate literature.

Connective Tissue↗
PubMed1986

[Blood vessels of the respiratory and olfactory mucosa of the rabbit. A light and transmission electron microscopy study].

In our study, light and electron microscopic findings in vessels of the rabbit nasal respiratory and olfactory mucosa are reported. In the respiratory mucosa, most of the subepithelial tissue is occupied by large, sinusoidal veins which usually display oblong profiles in cross sections, while in the olfactory region the venous vessels occur less often and show round profiles. The arterioles are located close to the perichondrium, while the capillaries appear all over the lamina propria in both tissues. Fenestrated and continuous endothelia can be observed in capillaries of both the respiratory and olfactory regions.

Animals↗
PubMedDate not supplied

Three-dimensional MR reconstruction images of skull base tumors.

Forty-eight patients with skull base tumors were evaluated prospectively with T1-weighted spin-echo two-dimensional (2D) magnetic resonance (MR) sequences, a three-dimensional (3D) MR TurboFLASH (fast low-angle shot) sequence, and a 3D reconstruction window technique. All patients underwent surgery with histopathologic correlation, and the three MR imaging techniques were compared to assess representation of tumor margins and the topographic relationship of tumor to surrounding tissue and adjacent vasculature. The best results were obtained with standard 2D spin-echo sequences after administration of the paramagnetic contrast agent gadopentetate dimeglumine. The 2D MR sequences gave the highest contrast-to-noise ratios, with decreasing values for 3D sequences and 3D reconstructions, respectively. Nevertheless, 3D MR imaging, by virtue of its good representation of adjacent structures, aided surgeons in planning surgical intervention. This study presents the technical features of 3D imaging of the skull base, the choices involved in its implementation, and its potential clinical applications.

Brain Neoplasms↗
PubMedDate not supplied

Treatment of recurrent respiratory tract infections with a polyvalent bacterial lysate: results of an open, prospective, multinational study.

This multicenter, open study, carried out in 14 countries in Europe, Latin America, and Asia, recruited 4965 patients suffering from recurrent respiratory tract infections to investigate the safety and acceptability of the oral bacterial lysate immunomodulator LW 50020. Patients remained in the study for 4 months (two 4-week courses of LW 50020 separated by a 28-day treatment-free interval and follow-up). The incidence of all adverse events was 7.2%; that of adverse drug reactions was 0.6%. Adverse drug reactions were mild to moderate and not more frequent in the large subgroup of patients (77%) with a known history of allergies or underlying respiratory diseases; however, the incidence of adverse events in this subgroup was twofold higher than in the study population as a whole, probably indicating a generally increased vulnerability to disease. No clinically relevant changes in laboratory variables followed treatment. Comparison of the first study period (first course of LW 50020 and drug-free interval) with the second study period (second course of LW 50020 and follow-up) showed an overall reduction of at least 50% in the number, severity, and duration of respiratory tract infections, the number of antibiotic and symptomatic treatments, and the number of days absent from school or work. Tolerability and acceptability were assessed as good or very good in 99% of patients who completed the study.

Adjuvants, Immunologic↗
PubMedDate not supplied

Three-dimensional magnetic resonance imaging in skull base lesions.

Three-dimensional (3D) magnetic resonance (MR) imaging is a new digital technique developed 2 years ago by a multidisciplinary group of head and neck surgeons, clinical radiologists, and mathematicians at the University of Munich. In this study, the clinical value of this method, which has been improved significantly during the last 9 months, is evaluated in lesions of the skull base. Our results indicate that 3D reconstruction based on two-dimensional (2D) MR images reveals topographic details of interesting structures. In addition, this method offers new possibilities for the preoperative planning of tumor resection, particularly in lesions close to the skull base. However, this imaging technique will have to be improved before it achieves widespread clinical use.

Carcinoma, Squamous Cell↗