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A Prokop

Publications and source records attributed to A Prokop.

At least 19 recordsLinked to original sources
PubMed1995

Syntaxin and synaptobrevin function downstream of vesicle docking in Drosophila.

In synaptic transmission, vesicles are proposed to dock at presynaptic active zones by the association of synaptobrevin (v-SNARE) with syntaxin (t-SNARE). We test this hypothesis in Drosophila strains lacking neural synaptobrevin (n-synaptobrevin) or syntaxin. We showed previously that loss of either protein completely blocks synaptic transmission. Here, we attempt to establish the level of this blockade. Ultrastructurally, vesicles are still targeted to the presynaptic membrane and dock normally at specialized release sites. These vesicles are mature and functional since spontaneous vesicle fusion persists in the absence of n-synaptobrevin and since vesicle fusion is triggered by hyperosmotic saline in the absence of syntaxin. We conclude that the SNARE hypothesis cannot fully explain the role of these proteins in synaptic transmission. Instead, both proteins play distinct roles downstream of docking.

Animals↗
PubMed1995

[Harvesting small amounts of autogenous spongiosa with a new set of instruments].

A new set of instruments with a special saw, a guide and a punch has been developed for harvesting of cancellous bone for small grafts. In a cadaver experiment use of the instruments was compared with the conventional open technique. Within half the operation time, nearly the same quantity of cancellous bone could be salvaged. In 29 clinical cases, bone defects resulting from 4 bone cysts, 6 enchondromas, 5 pseudarthroses and 5 fractures were closed with cancellous bone grafts harvested by means of the new instruments. In the case of 9 bone tumors the punches were used to obtain biopsy specimens, and sufficient tissue for the exclusion of malignancy was obtained in all 9. With the new instruments we are able to harvest cancellous bone for small grafts by a minimally invasive method.

Adolescent↗
PubMed1994

Normal function of the mushroom body defect gene of Drosophila is required for the regulation of the number and proliferation of neuroblasts.

In the developing central nervous system of Drosophila, proliferation follows a reproducible and well-described spatial and temporal pattern. This pattern involves a defined number and distribution of neural stem cells (neuroblasts), as well as a precisely regulated time course of division of these neuroblasts. We show that mutations in the mushroom body defect (mud) gene interfere with the regulation of this pattern in a rather specific manner. In the abdominal neuromeres a subset of neuroblasts prolongs the period of proliferation. Additional daughter cells persist into the imago. Similar defects are expressed in the anterior ventral nerve cord and in the lateral central brain region. In the mushroom body cortex, however, mutations in mud affect the proliferation pattern by increasing the number of neuroblasts. These additional neuroblasts behave like normal mushroom body neuroblasts according to their time course of proliferation and the specification of their progeny.

Animals↗
PubMed1994

[Fournier gangrene].

Since first described in 1883 by Fournier only 420 cases of Fournier's gangrene have been published worldwide during the last 100 years. The anatomic association between the fascies of penis, scrotum, perineum, groin and gluteal favors the fast spread of tissue necrosis. We report two cases in which the penis, scrotum and a great part of the trunk and extremities were affected. Extensive débridement, including removal of the scrotum, and antibiotic treatment permitted us to get rid of the symptoms. Reconstruction of the skin defects was done in a second step by applying mesh grafts. The histological findings correspond to those found in cases of necrotizing fasciitis. The basic difference between these two illnesses is their localization. While Fournier's gangrene, as a special form, is localized primarily in the anogenital area, fasciitis may arise in all locations. For successful treatment of Fournier's gangrene speedy radical débridement and local application of antibiotics to cover the entire area are required.

Adult↗
PubMed1994

Anastomotic aneurysms following aortofemoral vascular replacement.

Despite the advances in reconstructive vascular surgery, anastomotic aneurysms,--particularly in inguinal position--have remained an unsolved problem. Between 1985 and 1992 in 46 patients who underwent aortoiliac or aortofemoral bypass grafting 58 anastomotic aneurysms were operated in our institution. The mean interval between primary reconstruction and onset was 65.0 months. In 54% we observed real suture aneurysms. Technical faults are supposed to be the most causative factor in development of anastomotic aneurysm. The rate of recurrence after repair was 10%. There was no postoperative mortality. It is concluded that comprehensive follow-up is required after aortofemoral grafting. Because of the risk of peripheral embolization and local disruption surgical repair has to be done soon after the diagnosis of anastomotic aneurysm.

Adult↗
PubMed1994

Early tagma-specific commitment of Drosophila CNS progenitor NB1-1.

The developing central nervous system of many species expresses distinct segment-specific characteristics. We recently described the entire embryonic lineage of Drosophila neuroblast NB1-1 and showed that the composition of this lineage differs between the thoracic and abdominal tagmata with respect to the presence or absence of specific glial and neuronal components (Udolph, G., Prokop, A., Bossing, T. and Technau, G. M. (1993) Development 118, 765-775). Here, we demonstrate by heterotopic transplantations that tagma specificity of NB1-1 is determined in the neuroectoderm at the early gastrula stage (stage 7). Heterogenetic transplantation and mutant analysis show that the activity of the homeotic genes Ubx or abd-A is required for the expression of the abdominal variant of the lineage. Heat induction of Ubx or abd-A expression or their derepression in Polycomb mutant embryos can override thoracic determination several hours after gastrulation (stage 10/11). At that stage antibody stainings reveal both proteins to be present in NB1-1 during normal development. Possible mechanisms conferring the early tagma-specific determination are discussed.

Animals↗
PubMed1993

A common precursor for glia and neurons in the embryonic CNS of Drosophila gives rise to segment-specific lineage variants.

The nervous system consists of two classes of cells, neurons and glia, which differ in morphology and function. They derive from precursors located in the neurogenic region of the ectoderm. In this study, we present the complete embryonic lineage of a neuroectodermal precursor in Drosophila that gives rise to neurons as well as glia in the abdominal CNS. This lineage is conserved among different Drosophila species. We show that neuronal and glial cell types in this clone derive from one segregating precursor, previously described as NB1-1. Thus, in addition to neuroblasts and glioblasts, there exists a third class of CNS precursors in Drosophila, which we call neuroglioblasts. We further show that the NB 1-1 lineage exhibits characteristic segment-specific differences on the cellular level.

Abdomen↗
PubMed1993

[Heart failure, recurrent ventricular fibrillations and pleural mesothelioma in a young man who was treated in childhood with radiotherapy for Hodgkin's disease].

A case of 32-year old male with congestive heart failure and pleural effusion was described. When he was seven years old, he suffered from Hodgkin's disease and radiotherapy of the mediastinum and the neck was instituted. Twenty years later he developed acute myocardial infarction and then two episodes of circulatory arrest. The examinations revealed extensive, calcified stenoses of the coronary and cervical arteries. Risk factors of atheromatosis were absent. Moreover, the diagnosis of pleural mesothelioma which could also be caused by irradiation, was established.

Adult↗
PubMed1993

[Peripheral neurogenic tumors--surgical therapy of nerve sheath tumors. Review and personal results].

Nerve sheath tumors are rare tumors originating from the Schwann's cover cells. Neurinomas, neurofibromas and schwannomas can be separated due to a diverse growth behavior. 24 patients with neurinomas and 13 patients with neurofibromas were operated on from January 1, 1987 to December 31, 1992 at the Department of Surgery, University Cologne. A total of 10 patients received treatment during the last ten years because of schwannoma. The concepts of treatment and differentiation of the various tumors are demonstrated and compared based on the patients records and on a review of the literature.

Adolescent↗
PubMed1993

[Evaluation of mycologic and myco-serologic studies of materials derived from the respiratory tract of patients in the years 1986-1990].

The material for mycological studies consisted of 7146 samples of respiratory tract material derived from 7764 patients (6495 samples of sputum, 235 bronchial rinsings and 416 throat smears). Serological studies were performed with 684 samples of serum by application of indirect immunofluorescence (IF) and gel immunodiffusion (ID) tests. Candida- like fungi in amounts which were diagnostically significant (10(6) cells/ml) were found in 16.7% samples of sputum. among fungi isolated from sputum there were 14 species of Candida- like fungi, mainly C. albicans (76%) and 7 species of moulds (including A. fumigatus-0.7%). Fungi were isolated from bronchial washings in 23.4% of samples. Among the isolated strains, 12.6% of Candida albicans were resistant to 5-fluorocytosine and 14.1% were resistant to amphotericin B. Antibodies against C. albicans by application of both IF and ID were found in 2.2% samples of serum. Antibodies against A. fumigatus were present in 11.6% of samples.

Aspergillosis↗
PubMed1993

[Dog bite injuries with foreign body incorporation].

Dog-bite injuries represent a significant proportion of those injuries seen in a casualty department. Aside from primary wound management and determining the patient's vaccination status, X-ray examination is always indicated because of the possibility of foreign body inclusion as well as fractures. Plain X-ray views will reveal 88% of these foreign bodies. Our case involves a patient seeking workmen's compensation for a dog-bite injury and foreign body inclusion. Following removal of the foreign body, the patient was without symptoms and returned to his previous work.

Adult↗
PubMed1993

[Peripheral neurogenic tumors--surgical therapy of neuroblastoma. Review and personal results].

From January 1, 1982 to November 1, 1992 24 patients suffering from neuroblastoma were operated in the course of a neuroblastoma study at the Department of Surgery, Cologne University. 23 patients were in advanced stages 3, 4 and 4s. In 13 cases the initial operation was prior to applying chemotherapy, whereas in 10 cases chemotherapeutical treatment had taken place before. As a result of preoperative chemotherapy operation time and blood loss could be reduced, respectively, and despite delayed operative treatment a better demarcation of the tumor and an easier preparation were seen. Due to the preoperative treatment, tumors could be operated on more radically without increasing the rate of complications. Utilizing all possible surgical means, secondary and tertiary operative procedures and chemotherapeutical treatment. all patients in stage 2, 3 and 4s survived with safe remission. Nine of the fifteen patients in stage 4 died due to side effects from bone marrow transplantation or from recurrent neuroblastomas and not because of the surgical procedures. In the light of existing current multicenter neuroblastoma studies stage oriented surgical and chemotherapeutical concepts were developed, that are presented in this paper.

Adolescent↗
PubMed1992

[Spieghel hernia--a rare cause of acute abdomen].

Spieghelian hernia is a rare rupture of the abdominal wall along the linea semilunaris. Due to the fact that the rupture is overlain by the aponeurosis of M. externus abdominis, it is often not recognized in its early stage. In most cases the rupture neck is mostly very narrow and in 24.1% of all cases an incarceration of intestinal parts has ensued which may even lead to the development of an acute abdomen. The first choice therapy will consist in an operative support including the reposition of the hernial content and a possible resection of ischaemic organs as well as removal and sealing of the hernia. Because of the rarity of this sickness we report on a patient in our clinic who was operated as an emergency.

Abdomen, Acute↗