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Biomedical subjects

A Geissler

Publications and source records attributed to A Geissler.

At least 19 recordsLinked to original sources
PubMed2004

Rates of potential and actual cornea donation in a general hospital: impact of exhaustive death screening and surrogate phone consent.

BACKGROUND: In France at the end of 2002 the number of patients waiting for corneal grafts exceeded the number performed including the specimens imported from abroad. The major reason for the lack of grafts is that potential donors are not exhaustively identified and surrogate consent is difficult to obtain. This study reports the rates of potential cornea donation in a general French hospital when a transplant coordination team screened all deaths and made extended use of the phone to obtain familial consent. METHODS: All deaths in our institution were registered from February 2002 to January 2003. During this period, the transplant coordination team recorded on a daily basis the circumstances of death, medical contraindications, logistical problems, the consent rate, and the way patients' families were approached, namely, face-to-face or by phone interview. RESULT: Among 1088 deaths, 687 (63.1%) were unsuitable for corneal donation. All of the remaining 401 (36.9%) patients were considered for donation. Three hundred fifty four surrogates were interviewed by the transplant coordinator. In only 47 cases (18%) was it impossible to inform relatives and obtain donation consent. Two hundred seventy four families (77.4%) were contacted by phone (acceptance rate 60%) and 80 (22.6%) during a face-to-face interview (acceptance rate 72%). The acceptance rate was 62.7%. Finally, 443 corneas were retrieved, which represented 20.4% of institutional deaths. CONCLUSIONS: In a general hospital, systematic registration of deaths led to selection of 36.9% as potential corneal donors. The use of phone interviews allowed us to perform a procurement in 20.4%.

Corneal Transplantation↗
PubMed2003

Alterations of cerebral metabolism in patients with diabetes mellitus studied by proton magnetic resonance spectroscopy.

To evaluate possible pathophysiologic links between cerebral changes in diabetic patients detected by proton magnetic resonance spectroscopy and clinical as well as laboratory parameters. The brains of 30 patients with diabetes mellitus and 30 healthy volunteers were examined using a STEAM sequence (TR 1500 ms, TE 20 ms). We measured in occipital gray matter and parietal white matter in a 1.5-Tesla magnet. Laboratory parameters were acquired before and after the examination. In diabetic patients a significant elevation of the myo-inositol/creatine ratio in gray and white matter was present (p = 0.006). Choline/creatine ratio in gray matter was elevated compared to normal controls (p = 0.002). No correlation with laboratory parameters was detected. Myo-inositol was even more elevated in patients with polyneuropathy (p = 0.024). No correlation with age or sex was detected. The changes found in diabetes are similar to those found in patients with Alzheimer's disease, dialysis, and after renal transplant, suggesting a similar etiology. Elevated myo-inositol may not only indicate osmolar changes in glial cells but also glial cell alteration due to amyloid or amylin deposition with formation of neurofibrillary tangles, especially as these changes are found in all of these diseases and no correlation to osmolar deterioration exists.

Adult↗
PubMed2002

[Thoracic computed tomography in intensive care patients - evaluation of clinical usefulness].

PURPOSE: Computed tomography of intensive care patients requires transportation of the patient to the radiology department. This study analyses, whether this consumption of resources is justified by therapeutical and diagnostic consequences derived from helical computertomography of the chest. METHODS: 558 CT studies of the chest were compared with current bedside chest radiographs. The additional information of CT scans and their consequences were evaluated retrospectively. RESULTS: 388 (69.5 %) of these computed tomographies provided additional information compared with projection radiographs. 374 therapeutical procedures resulted from 266 (68.6 %) out of these 388 CT examinations. These therapeutical interventions were significantly more invasive than those 144 procedures derived from 170 (30.5 %) CT studies which did not show any additional findings compared with bedside chest radiographs. CONCLUSION: In more than two thirds (69.5 %) additional diagnoses were found with computertomography. Nearly one half of the CT studies resulted in additional findings and therapeutical consequences. Invasive therapeutical consequences were based on CT studies significantly more frequently than on bedside chest radiographs.

Adolescent↗
PubMed2001

Comparison of two-dimensional gradient echo, turbo spin echo and two-dimensional turbo gradient spin echo sequences in MRI of the cervical spinal cord anatomy.

The aim of this study was to assess the detectability and distinguishability of the cervical spinal cord, the anterior and posterior spinal roots and of the internal anatomy of the cord (distinction of grey and white matter). For this purpose 20 healthy volunteers were examined using a 1.5 T MR unit with 20 mT/m gradient strength and a dedicated circular polarized neck array coil. Three T2* weighted (w). 2D gradient echo sequences, two T2 w. 2D turbo spin echo (TSE) sequences and one T2 w. 2D turbo gradient spin echo (TGSE) sequence were compared. The multiecho 2D fast low angle shot (FLASH) sequence with magnetization transfer saturation pulse (me FLASH+MTS) yielded the best results for liquor/compact bone, liquor/spinal cord and grey/white matter contrast, as found with regions of interest (ROI) analysis. The single echo 2D FLASH sequence was significantly poorer than the two me FLASH+/-MTS sequences. Two-dimensional TGSE as well as 2D TSE with a 256 matrix and with a 512 matrix yielded the poorest results. In the visual analysis the contrast between liquor and compact bone, liquor and cord as well as liquor and roots was best with me FLASH+MTS, whereas grey/white matter distinction was best using me FLASH-MTS. In conclusion, we would therefore recommend the inclusion of an axial T2* w. multiecho 2D spoiled gradient echo sequence with magnetization transfer saturation pulse and gradient motion rephasing in a MR imaging protocol of the cervical spine.

Adult↗
PubMed2001

Versatility of the mitochondrial protein import machinery.

The vast majority of mitochondrial proteins are synthesized in the cytosol and are imported into mitochondria by protein machineries located in the mitochondrial membranes. It has become clear that hydrophilic as well as hydrophobic preproteins use a common translocase in the outer mitochondrial membrane, but diverge to two distinct translocases in the inner membrane. The translocases are dynamic, high-molecular-weight complexes that have to provide specific means for the recognition of preproteins, channel formation and generation of import-driving forces.

Biological Transport↗
PubMed2001

A presequence- and voltage-sensitive channel of the mitochondrial preprotein translocase formed by Tim23.

Proteins imported into the mitochondrial matrix are synthesized in the cytosol with an N-terminal presequence and are translocated through hetero-oligomeric translocase complexes of the outer and inner mitochondrial membranes. The channel across the inner membrane is formed by the presequence translocase, which consists of roughly six distinct subunits; however, it is not known which subunits actually form the channel. Here we report that purified Tim23 forms a hydrophilic, approximately 13-24 A wide channel characteristic of the mitochondrial presequence translocase. The Tim23 channel is cation selective and activated by a membrane potential and presequences. The channel is formed by the C-terminal domain of Tim23 alone, whereas the N-terminal domain is required for selectivity and a high-affinity presequence interaction. Thus, Tim23 forms a voltage-sensitive high-conductance channel with specificity for mitochondrial presequences.

Carrier Proteins↗
PubMed2001

Mitochondrial import driving forces: enhanced trapping by matrix Hsp70 stimulates translocation and reduces the membrane potential dependence of loosely folded preproteins.

The mitochondrial heat shock protein Hsp70 (mtHsp70) is essential for driving translocation of preproteins into the matrix. Two models, trapping and pulling by mtHsp70, are discussed, but positive evidence for either model has not been found so far. We have analyzed a mutant mtHsp70, Ssc1-2, that shows a reduced interaction with the membrane anchor Tim44, but an enhanced trapping of preproteins. Unexpectedly, at a low inner membrane potential, ssc1-2 mitochondria imported loosely folded preproteins more efficiently than wild-type mitochondria. The import of a tightly folded preprotein, however, was not increased in ssc1-2 mitochondria. Thus, enhanced trapping by mtHsp70 stimulates the import of loosely folded preproteins and reduces the dependence on the import-driving activity of the membrane potential, directly demonstrating that trapping is one of the molecular mechanisms of mtHsp70 action.

Calcium-Transporting ATPases↗
PubMed2000

Biogenesis of the yeast frataxin homolog Yfh1p. Tim44-dependent transfer to mtHsp70 facilitates folding of newly imported proteins in mitochondria.

Tim44 is an essential component of the mitochondrial inner membrane protein import machinery. In this study we asked if Tim44 is of relevance in intramitochondrial protein folding. We investigated the role of Tim44 in the biogenesis of the authentic mitochondrial protein Yfh1p, the yeast homolog of mammalian frataxin, which was recently implicated in Friedreich ataxia. After inactivation of Tim44, binding of mitochondrial heat shock protein (mtHsp)70 to translocating Yfh1p and subsequent folding to the native state was nearly completely blocked. Residual amounts of imported Yfh1p showed an increased tendency to aggregate. To further characterize the functions of Tim44 in the matrix, we imported dihydrofolate reductase (DHFR) as a model protein. Depletion of Tim44 allowed import of DHFR, although folding of the newly imported DHFR was delayed. Moreover, the depletion of Tim44 caused a strongly reduced binding of mtHsp70 and Mge1 to the translocating polypeptide. Subsequent dissociation of mtHsp70 from imported DHFR was delayed, indicating that mtHsp70-substrate complexes formed independently of Tim44 differ from the complexes that form under the control of Tim44. We conclude that Tim44 not only plays a role in protein translocation but also in the pathways of mitochondrial protein folding.

Biological Transport↗
PubMed2000

Mixed capillary/lymphatic malformation with coexisting port-wine stain: treatment utilizing 3D MRI and CT-guided sclerotherapy.

BACKGROUND: Lymphatic malformation, a benign malformation of the skin and the subcutaneous tissues, is divided into two major groups: the classical and the localized forms. Pathologically lymphatic malformation often consists of sequestered lymphatic cisterns with thick muscle walls lying deeply in the subcutaneous tissue. Communicating via dermal lymphatic channels with superficial pseudovesicles, they can vary in size depending on the pressure transmitted by the cisterns beneath. METHODS: We present a patient with mixed capillary/lymphatic malformation and coexisting port-wine stain since birth. To demonstrate the anatomic extent and the subcutaneous involvement we performed a 3D reconstruction of a magnetic resonance imaging (MRI). The diagnostic procedures, therapeutic possibilities, and complications regarding this rare appearance are reviewed. RESULTS: Good results could be obtained with CO2 laser vaporization of the superficial lesions and computed tomography (CT)-guided transcutaneous sclerotherapy for the deeper cisterns with doxycycline. CONCLUSION: The combination of CO2 laser treatment and sclerotherapy with doxycycline seems to present a treatment option for cutaneous and subcutaneous lymphangioma circumscriptum with rare side effects.

Adult↗
PubMed2000

[Stent angioplasty of pelvic artery stenosis with MRI control: initial clinical results].

PURPOSE: To investigate the feasibility of MR-guided stent angioplasty of iliac artery stenoses under passive visualization. MATERIAL AND METHODS: Three patients with short, concentric stenoses of the iliac arteries were enrolled. The vascular interventions were performed on a 1.5 T MR scanner (Magnetom Symphony, Siemens, Erlangen, Germany). Stents, guidewires, and balloon catheters were visualized on the basis of susceptibility artifacts. Contrast-enhanced MR angiography (ceMRA) was used to localized the stenosis prior to stent deployment. Nitinol stents were placed under MR-guidance using a fast 2D gradient echo technique. Balloon dilatiation was performed with an angioplasty catheter inflated with diluted gadolinium-DTPA. Postinterventional results were evaluated by ceMRA, DSA, and Doppler indices. RESULTS: Position of the stent, stent deployment, and balloon dilatation were depicted by MR. All stents were correctly placed within the stenosis. Stent positions as monitored by MRI were identical to those seen on DSA images. All patients were treated successfully by the MR-guided intervention. CONCLUSION: An MR-guided stent angioplasty of simple iliac artery stenosis is feasible under passive visualization.

Aged↗
PubMed2000

[Pulmonary metastasis of extranodal high malignancy B-cell non-Hodgkin lymphoma of the bulbus duodeni and pylorus of the stomach].

We report a 71-year-old female patient with repeated vomitus, meteorism, epigastric pain and reflux for more than four month. She had a palpable mass in the upper abdomen and lost 7 kg of weight during the last four months. Chest X-ray showed two masses, 2 cm and 3 cm in diameter, in the left and right lower lung. A stenosing polypoid mucosal swelling in the antrum and the duodenal bulb. The pulmonal masses were biopsied under CT-guidance. Biopsy proved a high malignant B-cell non-Hodgkin's lymphoma of the stomach. The masses in the lung were identified as metastases of the gastrointestinal lymphoma. In conclusion on this tumor was an extranodal non-Hodgkin's lymphoma stadium BE IV according to Musshoff. A CHOP-chemotherapy was initiated. Restaging after three cycles of CHOP revealed a complete remission. Primary gastrointestinal non-Hodgkin's lymphomas are relatively rare neoplasms of the abdomen. Unusual and interesting in this case ist the metastatic pattern involving the lung periphery without local lymph node metastases.

Aged↗
PubMed2000

Membrane potential-driven protein import into mitochondria. The sorting sequence of cytochrome b(2) modulates the deltapsi-dependence of translocation of the matrix-targeting sequence.

The transport of preproteins into or across the mitochondrial inner membrane requires the membrane potential Deltapsi across this membrane. Two roles of Deltapsi in the import of cleavable preproteins have been described: an electrophoretic effect on the positively charged matrix-targeting sequences and the activation of the translocase subunit Tim23. We report the unexpected finding that deletion of a segment within the sorting sequence of cytochrome b(2), which is located behind the matrix-targeting sequence, strongly influenced the Deltapsi-dependence of import. The differential Deltapsi-dependence was independent of the submitochondrial destination of the preprotein and was not attributable to the requirement for mitochondrial Hsp70 or Tim23. With a series of preprotein constructs, the net charge of the sorting sequence was altered, but the Deltapsi-dependence of import was not affected. These results suggested that the sorting sequence contributed to the import driving mechanism in a manner distinct from the two known roles of Deltapsi. Indeed, a charge-neutral amino acid exchange in the hydrophobic segment of the sorting sequence generated a preprotein with an even better import, i.e. one with lower Deltapsi-dependence than the wild-type preprotein. The sorting sequence functioned early in the import pathway since it strongly influenced the efficiency of translocation of the matrix-targeting sequence across the inner membrane. These results suggest a model whereby an electrophoretic effect of Deltapsi on the matrix-targeting sequence is complemented by an import-stimulating activity of the sorting sequence.

Amino Acid Sequence↗
PubMed2000

Magnetic resonance monitoring of stent deployment: in vitro evaluation of different stent designs and stent delivery systems.

RATIONALE AND OBJECTIVES: To evaluate MR imaging features of commercially available stents before, during, and after in vitro deployment as a step toward MR-guided stent deployment. METHODS: Fourteen stents were deployed in a phantom under MR monitoring at 1.5 T by using a gradient-echo sequence. Device visibility was rated on a four-point scale (excellent, fair, poor, not visible). RESULTS: The Memotherm stent and the rolling membrane (RM) Wallstent showed excellent stent visibility and at least fair scores for artifact-induced narrowing of the stent lumen. Three stents (Palmaz, AVE, Easy Wallstent) showed excellent visibility of the stent but no visible lumen. Five stents (Strecker, Accuflex, Hemobahn, Passager, Sinus) displayed fair visibility. The delivery catheters of four stent systems (Smart, Vascucoil, Symphony, ZA) displayed severe black hole artifacts. CONCLUSIONS: The imaging features of several stent systems might be suitable for MR-guided intervention. The Memotherm and the Wallstent RM combine good visibility of the stent and the lumen.

Blood Vessel Prosthesis↗
PubMed1999

Postpartum cerebral angiopathy associated with the administration of sumatriptan and dihydroergotamine--a case report.

Cerebral angiopathy of the postpartum period is a rare entity, sometimes promoted by vasoconstrictives drug prescription. Its clinical presentation includes headaches, seizures and focal neurological deficits, which develop shortly after a normal pregnancy. The diagnosis is based on clinical findings and angiography, showing multiple narrowing of the intracranial cerebral arteries. This neurological feature is reversible and the clinical outcome is good. We report a case of benign cerebral angiopathy in a 20-year-old woman in the postpartum period, occurring after administration of sumatriptan and ergot derivates.

Adult↗
PubMed1999

Economic impact of a rational use of antibiotics in intensive care.

OBJECTIVE: To evaluate the economic impact of a rational policy in antibiotic treatment. DESIGN: Comparative study with a retrospective and a prospective part. SETTING: An 11-bed intensive care unit (ICU) in a general hospital. PATIENTS: All patients admitted to the unit in 1994, 1995 and 1996. INTERVENTIONS: In 1995, a program of cost control was started and a contract of agreed objectives signed with the director of the hospital. This contract included a commitment to refund the eventual savings in order to improve the quality of care. Prescribing protocols were established by consensus as guidelines for a rational policy in antibiotic therapy. MEASUREMENTS AND RESULTS: The cost of antibiotic therapy, the patients' characteristics and the incidence of nosocomial infection were compared prior to and during the program. The expenses for antibiotic drugs decreased by 19% in 1995 and by 22% in 1996. Most of the savings were refunded to the ICU and contributed to the employment of an additional nurse and the purchase of new material. In number of patients, type of disease, mean age, Simplified Acute Physiology Score, occupancy rate, length of stay, omega score, artificial ventilation, readmission within 7 days, mortality and incidence of nosocomial infection, no significant difference was found. CONCLUSIONS: We proved a positive economic impact of a rational policy in antibiotic therapy realized with a contract of agreed objectives. The savings made while applying our program of cost control were used to improve the quality of care.

Anti-Bacterial Agents↗