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Biomedical subjects

A Enderle

Publications and source records attributed to A Enderle.

At least 19 recordsLinked to original sources
PubMed2001

Macroencapsulation of rat islets without alteration of insulin secretion kinetics.

Transplantation of encapsulated islets may restore endogenous insulin secretion in type 1 diabetics with no need of lifetime immunosuppression of the recipient. A biomaterial should be developed which combined immunoisolation with rapid and efficient diffusion of glucose and insulin. Rat islets were macroencapsulated in capillaries (molecular cut off 50 kD) of differently modified polysulphone. Macroencapsulated islets were perifused to study the kinetics of glucose induced insulin secretion into the perifusion medium. Blending polysulphone (PSU) with poly vinyl pyrrolidone or sodium dodecyl sulphate was not suited for islet macroencapsulation since glucose induced insulin release was absent after encapsulation. Hydroxy methylation (CH2OH) of PSU improved the secretory behaviour of macroencapsulated islets depending on the degree of substitution (DS). At 0.8 DS glucose induced insulin secretion was delayed and inefficient. At maximal degrees of PSU-substitution (1.8) the kinetics of insulin release and the efficiency of insulin release were very similar to that observed of free floating islets. In conclusion, highly substituted hydroxy methylated polysulphone allows a rapid and efficient insulin release after macroencapsulation and is suited for the further development of a bioartificial pancreas.

Animals↗
PubMed2001

In vitro test of new biomaterials for the development of a bioartificial pancreas.

The implantation of macroencapsulated islets has the potential to restore endogenous insulin secretion in type 1 diabetics, with no need for lifetime immunosuppression. To match the physiological fluctuations of blood glucose concentrations with appropriate insulin release, the macroencapsulation material must combine immunoprotection with optimal diffusion properties for glucose and insulin. The impact of chemical modifications of polysulphone (PSU) capillary polymers with a cutoff of 50 kD on glucose-induced insulin secretion of macroencapsulated rat islets was studied in perifusion experiments. The insulin release of free-floating islets showed the typical rapid response to glucose stimulation. Total insulin release (AUC between minute 30 and 120 of perifusion) reached 117+/-22 ng/ml. Blending PSU with polyvinylpyrrolidone or sodium-dodecyl-sulfate was not suitable for islet macroencapsulation, since glucose-induced insulin release was absent or disturbed. Hydroxy-methylation (CH2OH) of PSU improved the secretory behavior of macroencapsulated islets depending on the degree of PSU substitution (DS 0.8, AUC 62+/-15 ng/ml; DS 1.8, 111+/-24 ng/ml). In highly substituted PSU-capillaries the kinetics of glucose-induced insulin release was very similar to that observed in free-floating islets. Two consecutive glucose stimulations potentiated insulin release of free-floating islets during the second period of stimulation. Furthermore, freshly isolated macroencapsulated islets responded with more efficient insulin secretion after the initial priming. In conclusion, in vitro membrane screening identified highly substituted hydroxy-methylated PSU as the material of choice for islet encapsulation in a bioartificial pancreas.

Animals↗
PubMed1999

Hard fallow deer antler: a living bone till antler casting?

Deer antlers are the only mammalian bone structures which regenerate completely every year. Once developed, antlers are cleaned of the velvet-like skin. Presently it is believed that due to velvet shedding the blood supply is interrupted in the solidifying antler bone. Histological examinations were made on different parts of fallow deer antlers investigated from the time of velvet shedding till the antler casting. The present study on hard (polished) antlers revealed living bone with regions presenting living osteocytes, active osteoblasts, osteoid seams and even early stages of trabecular microcallus formation, thus indicating to a continuous bone remodeling. A well developed vascular system was found despite the presence of hard antler bone. The pedicle bone exhibits a rich supply of capillaries and vessels connected to the spongy core of the main branch and the compact bone as well. There is evidence that hard fallow deer antlers possess a functioning vascular system that "keeps the antler moist" resulting in a high impact resistance when fights are most frequent. As late as 3 weeks prior to antler casting a large number of living cells were discovered within the antler core. As we have no doubt that parts of the polished fallow deer antler represent a living bone, we have concluded that a sufficient blood supply of the antler core is maintained almost till the time of antler casting by vessels passing through the antler base.

Animals↗
PubMed1998

Dwarfism and gigantism in historical picture postcards.

A collection of 893 historical picture postcards from 1900 to 1935, depicting dwarfs and giants, was analysed from medical and psychosocial viewpoints. In conditions such as 'bird headed dwarfism', achondroplasia, cretinism, so-called Aztecs or pinheads, Grebe chondrodysplasia, and acromegalic gigantism, the disorder could be diagnosed easily. In hypopituitary dwarfism, exact diagnosis was more difficult because of heterogeneity. The most common conditions depicted were pituitary dwarfism and achondroplasia. Most of those with gigantism had pituitary gigantism and acromegaly. Brothers and sisters or parents and their children provided evidence of mendelian inheritance of some of these disorders. The cards suggest that being put on show provided, at least in some cases, social benefits.

Acromegaly↗
PubMed1997

Avascular osteonecrosis of the acetabulum.

OBJECTIVE: To investigate the possible occurrence of osteonecrosis in the acetabulum in patients with non-traumatic necrosis of the femoral head. DESIGN AND PATIENTS: One hundred and seventy-nine patients with non-traumatic femoral head necrosis were assessed by MRI and radiography for the presence of acetabular necrosis. Three criteria were established to differentiate between osteonecrosis and osteoarthritic changes: (1) heterogeneous morphology and irregular contours of the lesion; (2) typical demarcation lines of osteonecrosis; (3) deficient accumulation of intravenous gadolinium in the affected regions. RESULTS: In four patients histological confirmation of acetabular necrosis was obtained. The MR analysis of 22 acetabula (9.5% of those examined) showed changes which suggested osteonecrosis. No cystic lesions were demonstrated in the subchondral bone of any patient. Two cases of acetabular necrosis were found without an ipsilateral femoral head necrosis. In two patients of the 14 who had undergone total hip replacement following necrosis of the femoral head, aseptic loosening of the acetabular component was found. CONCLUSION: The study suggests that acetabular necrosis may be an accompaniment to aseptic necrosis of the femoral head. Further work is required to assess its importance in premature loosening of the acetabular element of total hip arthroplasty.

Acetabulum↗
PubMed1996

Aggressive osteoblastoma with focal malignant transformation and development of pulmonary metastases. A case report with a review of literature.

We report the case of a 57-year-old woman with an unusually fast-growing and destructive osteoblastic tumor affecting the left humeral head. On histopathologic examination, most of the initial tumor revealed the characteristic morphologic features of a benign-appearing aggressive osteoblastoma. Based upon the presence of a few small scattered areas composed of atypical osteoblasts in abundant lace-like osteoid showing vascular permeation, the definitive diagnosis was that of an osteoblastoma with focal malignant transformation to well-differentiated osteosarcoma. Molecular biologic analysis revealed a splice mutation at the exon 5 donor site of the p53 gene, clearly indicating a malignant potential of the tumor. The proximal third of the humerus was resected en bloc and replaced by an uncemented modular endoprosthesis. Five months after surgery, an extensive local soft tissue recurrence occurred. Eight months postoperatively, a further massive recurrent tumor had developed an multiple pulmonary metastases became evident. Chemotherapy caused a marked decrease in the size of the soft tissue recurrences and the lung metastases showed no further increase of their number and size. Osteoblastomas with conversion to osteosarcoma should be considered a separate clinicopathologic tumor entity to be distinguished from genuine osteosarcoma. All cases of malignantly transformed conventional and aggressive osteoblastomas reported to date have shown a conversion to low- or high-grade osteosarcomas only in recurrent tumors. The present case supports the concept that osteoblastomas may primarily undergo early malignant transformation. Osteoblastomas with conversion to osteosarcoma require an aggressive surgical approach followed by chemotherapy in the hope of prolonging life expectancy or obtaining a cure.

Bone Neoplasms↗
PubMed1990

[Sudeck disease].

In 1900, the Hamburg surgeon P.H.M. Sudeck was the first to describe the clinical and radiological symptomatology of the disorder to which he later lent his name. He devoted his scientific career to this disorder, "acute inflammatory atrophy" of bone and soft-tissue as he called it. He elaborated the histology of the disorder with his students and advocated the pathogenic peripheral humoral theory. In later years seven further attempts to explain the pathogenesis were published. The present paper notes that this disorder, which can be divided into three distinct stages, is diagnosed mainly on the basis of clinical factors, above all in the early stage, and that x-rays in the early stages are difficult to differentiate from those of immobilisation osteoporosis since both disorders can manifest as patchy rare fraction and fibrous osteolysis in subchondral bone and old growth plates. Moreover, the author also notes that 10% of all Sudeck cases are not preceded by trauma; these must be understood as spontaneous Sudeck or as Sudeck after distant disturbances. A few sources also refer to Sudeck's dystrophy in the presence of lymphatic congestion. Another, special form of Sudeck's atrophy, is the shoulder-hand syndrome which, however, cannot always be differentiated precisely from rheumatic disorders or dystrophic contractures.

Adult↗
PubMed1988

[Biologico-mechanical behavior of bone in osteomalacia and in phosphate diabetes in adulthood].

The main orthopedic complications in osteomalacia, skeletal deformities, Looser's transformation zones and fractures, are described. The limited value of a Looser's transformation zone as a radiographic diagnostic criterion for osteomalacia is mentioned, because such zones can also occur in other bone diseases with abnormal remodeling. This paper also outlines the differential diagnosis of a Looser zone against a stress fracture. In osteomalacia and phosphate diabetes the biological and mechanical properties of bone are different. In adult phosphate diabetes radiological examination is more likely to reveal osteosclerosis than a radio-opaque bone. For this reason we investigated the bone healing process in five adult patients with osteomalacia and in six with phosphate diabetes. In spite of the small number of patients we may assume that bone healing after surgery is delayed in phosphate diabetes compared with osteomalacia, in which a normal bone healing tendency is present.

Adult↗
PubMed1981

[Diagnosis of focal spinal diseases - a critical review].

The article offers a critical review of the diagnosis of focal diseases of the vertebral column, based on 200 histological vertebral column examinations. The findings obtained by means of the roentgenological, histological and bacteriological examinations can be subdivided into 6 groups: 1. Non-specific and specific cases of spondylitis (59 patients); 2. Systemic malignant diseases and primarily malignant tumours (23 patients); 3. Metastases (71 patients); 4. Benign tumours (11 patients); 5. Miscellaneous cases (28 patients) and 6. Unclarified cases (8 patients). The authors comment on the following points with specific reference to the results obtained by them: a) Possibilities and limitations of roentgenological diagnosis: roentgenologically, the inflammatory diseases are most easy to identify, but is not always possible to differentiate safely between non-specific, specific and plasmacellular spondylitis. There are clear limitations to the diagnosis of the type of focal diseases of the spinal column; this applies particularly to the benign and malignant types of tumours. b) Necessity of arriving at an accurate diagnosis: it is imperative to aim at an accurate diagnosis before any meaningful therapy can be initiated. The mandatory need for this is explained via examples covered by the present study. c) Closed or open biopsy: it is shown by means of a review of the literature that open biopsy yields more representative material for the histological examination than closed needle biopsy. It goes without saying that this is a true prerequisite for an accurate histological diagnosis. In this connection, the authors go into the details of the difficulties governing any histological examination. d) informative value of further additional examinations: Scintigraphy, tomography and computer tomography may be valuable aids in the discovery and better visualisation of a vertebral focus, but they are not helpful in arriving at a diagnosis regarding the type of focus involved. Laboratory examinations are not very helpful, either. e) Accuracy of the authors' own diagnostic measures: in spite of open biopsy, 177 cases only out of 200 (88%) could be diagnosed on a purely histological basis. In 12 further cases, diagnosis was established after correlation of the histological finding with the x-ray film. 8 cases (4%) could not be clarified. In 7 patients (3.5%) it must be assumed that the focus was not located despite open biopsy.

Adolescent↗
PubMed1979

[Differential diagnosis of a metastasizing adamantinoma of the tibia and fibula (author's transl)].

A case of an adamantinoma of the tibia and fibula is described in a 10-year-old girl who died after 17 years with pulmonary metastasis. For a long time, an exact diagnosis couldn't be made. Histologically the lesion was called chronic osteomyelitis (Brodie's abscess), synovial sarcoma and spindle cell sarcoma. The revision of the histological sections revealed a fibrous dysplasia-like pattern in the first lesion of the tibia with tiny foci of an epitheloid-like pattern. This had could be the key to the right diagnosis, because sometimes adamantinoma of long bones is associated with a fibrous dysplasia-like pattern. The reason for misinterpretation of the histological features is seen in the typical variable histological pattern of this tumor (basaloids, squamoid, spindled and tubular pattern). In this connection is refered to the necessity to correlate the histological feature with the X-ray in making diagnosis in bone pathology.

Adult↗
PubMed1979

[Temporary plugging of cystic bone tumors by bone cement (author's transl)].

Methylmethacrylate bone cement was used to refill bony defects following excisional biopsy of supposed benign or semimalign bone tumors. This procedure offers several advantages: the anatomical situation at the site of the lesion will not be altered, that means the functions of the joint and the continuity and stability of the bone will be preserved; the histological examination of the tissue is possible without a hurry; the follow up of the lesion is easily possible by X-ray-examination; further therapeutic procedures can follow without restriction, for example if the histology discovered an unsuspected malignant tumor or if the follow-up revealed a recurrency. In addition a favorable effect is the necrosis of tumor cells, eventually left behind in the bone, by the action of zytotoxic monomer and heat, originated during the polymerisation of the methylmethacrylate. In benign or semimalignant bone tumors the cement has to be removed after an adequate observation period; at this occasion the cavity again is curetted and then filled with autologous bone grafts. Since 1972 we treated 13 bone lesions by this method of "temporary bone cement plugging". The lesions were 5 giant cell tumors, 2 aneurysmal bone cysts, 2 simple bone cysts, 1 osteosarcoma, 1 malignant lymphoma, and 2 metastases of hypernephroid carcinoma. In the case of osteosarcoma an amputation was performed just after the diagnosis was made. In the other cases no local recurrances up to now were seen.

Adult↗