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Biomedical subjects

M Zwaan

Publications and source records attributed to M Zwaan.

At least 19 recordsLinked to original sources
PubMed2000

Magnetic resonance imaging volumes of the hippocampus and the amygdala in women with borderline personality disorder and early traumatization.

BACKGROUND: Based on findings of stress-induced neural disturbances in animals and smaller hippocampal volumes in humans with posttraumatic stress disorder), we hypothesized that patients with borderline personality disorders (BPD), who often are victims of early traumatization, have smaller volumes of the hippocampus and the amygdala. We assumed that volumes of these brain regions are negatively correlated with traumatic experiences and with neuropsychological deficits. METHODS: We studied 21 female patients with BPD and a similar group of healthy controls. We performed clinical assessments, a modified version of the Childhood Trauma Questionnaire, and magnetic resonance imaging volumetric measurements of the hippocampus, amygdala, temporal lobes, and prosencephalon. Neuropsychological testing included scales on which disturbances in BPD were previously reported. RESULTS: The patients with BPD had nearly 16% smaller volumes of the hippocampus (P<.001) and 8% smaller volumes of the amygdala (P<.05) than the healthy controls. The results for both hemispheres were nearly identical and were controlled for the volume of the prosencephalon and for head tilts. The volumes of the hippocampus were negatively correlated with the extent and the duration of self-reported early traumatization only when BPD and control subjects were considered together. Levels of neuropsychological functioning were associated with the severity of depression but not with the volumes of the hippocampus. CONCLUSION: In female patients with BPD, we found reduction of the volumes of the hippocampus (and perhaps of the amygdala), but the association of volume reduction and traumatic experiences remains unclear. Arch Gen Psychiatry. 2000;57:1115-1122.

Adult↗
PubMed2000

Current practice of temporary vena cava filter insertion: a multicenter registry.

PURPOSE: To evaluate the current practice of temporary vena cava filter placement and its complications. MATERIALS AND METHODS: A multicenter registry was conducted from May 1995 until May 1997 using a standardized questionnaire. One hundred eighty-eight patients were evaluated. Patient characteristics, filter indications, filter characteristics, and complications were registered. RESULTS: Deep vein thrombosis was proven in 95.2% of the patients. Main filter indication was thrombolysis therapy (53.1%). Average filter time was 5.4 days. An Antheor filter was inserted in 56.4%, a Guenther filter in 26.6%, and a Prolyser filter in 17.%. Transfemoral filter implantation was slightly preferred (54.8%). Four patients died of pulmonary embolism (PE) during filter protection. Major filter problems were filter thrombosis (16%) and filter dislocation (4.8%). When thrombus was found in or at the filter before explantation, additional thrombolysis was performed in 16.7%, additional filter implantation in 10%, and thrombus aspiration in 6.7%; 4.8% of filters were replaced with permanent filters. DISCUSSION: Temporary vena cava filters are placed to prevent PE in a defined patient population. Despite their presence, PEs still occur in a small percentage. Problems of filter thrombosis and dislocation have to be solved. CONCLUSION: The results of this multicenter registry support the need for innovative filter design, as well as a randomized, prospective study.

Adolescent↗
PubMed1999

[The in-vitro evaluation of different embolectomy catheters for the treatment of acute pulmonary embolism].

INTRODUCTION: Pulmonary embolism (PE) is one of the most common cardiovascular diseases and frequently causes death. As a rule, PE is treated with thrombolytic therapy or surgical thrombectomy. MATERIALS AND METHODS: In an in vitro model of the right lung, we tested four different percutaneous transluminal thrombectomy devices: a pigtail-catheter with an angled 3-cm (40 degrees) distal tip, the clot-buster, the hydrolyser catheter, and a modified hydrolyser. In 16 consecutive and repetitive experiments fresh thrombi were inserted and we evaluated the effectiveness of the system with respect to time, fragment size, reduction of the Miller score, and handling. RESULTS: Mean intervention times of the catheter systems were 23 min (pigtail), 14.4 min (modified hydrolyser), 13.8 min (clot-buster), and 10.8 min (hydrolyser). The maximum size of the produced fragments range from 0.5 to 3.5 mm by the pigtail and from 0.5 to 1 mm by the other systems. The Miller score reduction was from 14.4 to 2.8 (pigtail), 13.8 to 1.8 (clot-busters), 14.6 to 1.2 (hydrolyser), and 16.4 to 1 (modified hydrolyser). DISCUSSION: All four catheter systems were effective in the treatment of pulmonary embolism. The pigtail catheter is the most simple system but more time consuming and less effective in the fragmentation of emboli and reduction of the Miller score compared to the other three catheter systems. These systems were comparable in our model but especially the handling of the hydrolyser was encouraging.

Acute Disease↗
PubMed1999

Local effect of three nonionic contrast media on the arterial blood flow velocity during iliofemoral arteriography.

RATIONALE AND OBJECTIVES: To investigate the influence of nonionic contrast media on the arterial blood flow velocity (BFV) during iliofemoral arteriography. MATERIALS AND METHODS: Iliofemoral arteriography with three contrast media--iopromide, iopamidol, and iodixanol--was carried out in 55 patients in a prospective manner. Hemodynamic changes were investigated using the change in the maximal systolic BFV in the dorsal artery of the foot and were recorded by simultaneous Doppler sonography. RESULTS: Comparable reductions in BFV were demonstrated for iopromide and iopamidol, but the iso-osmolar iodixanol produced no change in the maximal systolic BFV. The reduction in BFV by iopromide and iopamidol is attributed to a vasoconstrictive effect on the resistance vessels and is explained by a direct depolarization of the vascular smooth muscles with predamaged endothelium; the effect lasts for less than 1 minute. The time from the greatest change in BFV until the baseline value was achieved (recovery time) depended on the degree of vascular damage present. This can be explained by the inadequate compensation in circulatory regulation of patients with peripheral arterial occlusive disease. Iodixanol's lack of influence on BFV may result because its osmolality and chemotoxicity differ from those of iopromide and iopamidol. CONCLUSIONS: The peripheral hypoxemia observed in patients with arteriosclerotic vascular changes can be expected to increase through the vasoconstrictive effect of iopromide and iopamidol, whereas no such blood flow deficit is to be expected with the use of iodixanol. Nevertheless, the reduction in blood flow is of short duration and thus will probably not contribute significantly to this hypoxemia.

Adult↗
PubMed1997

[The angiography of kidney transplant arteries using carbon dioxide].

BACKGROUND AND OBJECTIVE: After renal transplantation hypertension occurs in 60-80% of patients, in 3-23% of them due to renal artery stenosis in the transplanted kidney. Angiographic assessment of the severity of the stenosis would best be done with a non-nephrotoxic contrast medium. We investigated the use of carbon dioxide, a bubble-forming contrast medium excreted via the lung, for its suitability in the angiography of the arterial system in the renal transplant. PATIENTS AND METHODS: In an uncontrolled series of observations on six patients with renal transplants and hypertension who were being treated with three or four antihypertensive drugs, the transplant's arteries were demonstrated with carbon dioxide, injected by Seldinger technique into the ipsilateral femoral artery, and the results recorded by subtraction angiography. RESULTS: The angiograms demonstrated postoperative kinked renal artery, a plaque in the external iliac artery, and a sharply angled origin of the external iliac artery in one case each, and three normal cases. CONCLUSIONS: Carbon dioxide is a suitable medium for demonstrating renal arteries in a transplanted kidney and is preferable to conventional contrast media for the angiographic diagnosis of possible renal artery stenosis.

Adult↗
PubMed1997

[Cinematographic functional diagnosis of swallowing after plastic reconstruction of large tumor defects of the mouth cavity and pharynx].

BACKGROUND: Reestablishing good swallowing function after resection and reconstruction of head and neck tumors is very important for our patients' well-being. Today many different surgical concepts for reconstruction after tumor surgery are in common use. It is necessary to establish a good diagnostic procedure for postoperative assessment of the swallowing function. High-speed cineradiography at a minimum of 50 frames per second is well established for evaluating swallowing problems in head and neck patients. METHODS: Thirty-six patients divided into three groups were examined using high speed cineradiography after surgical treatment of pharyngeal and oral cavity cancer. Group 1 (n = 12) included patients with a subtotal or total tongue resection and reconstruction with infrahyoid myofascial flap and jejunal flap; Group II (n = 8), patients with total resection of the oropharynx soft palate and velum and reconstruction with a free radial forearm flap; Group III (n = 15), patients with total laryngopharyngektomy and reconstruction with jejunal flap and siphon and with or without repair of the digastric muscle. RESULTS: Group I: All patients with tongue reconstruction were able to swallow normally from the oral cavity into the pharynx. All patients had normal bolus propulsion because of a good tongue volume and tongue motility. There was only one case of aspiration after total glossectomy with the larynx left in place. All patients could swallow with the head and neck in a normal position. Group II: All patients with reconstruction of the soft palate and velum were able to initiate proper bolus propulsion without nasal regurgitation or rhinolalia aperta. Only one patients suffered from chronic aspiration after hemiresection of the oropharynx and hypopharynx. Group III: All patients with pharynx reconstruction had no problems with bolus transfer through the reconstructed pharynx. Aspiration into the reconstructed pharynx was a major problem for those patients without repair of the digastric muscle (5/8 = 63%). Better results were observed in the patients who underwent repair of the digastric muscle. There was only one case (13%) of aspiration. CONCLUSIONS: By using high-speed cineradiography it is possible to make a detailed description of the swallowing function after extensive surgical treatment of pharyngeal and oral cavity cancer. We think that high-speed cineradiography is a very sensitive diagnostic procedure capable of detecting all functional aspects of swallowing. High-speed cineradiography should be one of the standard diagnostic studies performed surgery of the oral cavity and pharynx.

Adult↗
PubMed1997

[Angiography during interventional procedures with carbon dioxide (CO2) (carbo-angiography) in patients with increased contrast media risk].

Within the last 18 months we examined 130 patients with known complications or contraindications using iodinated contrast media for angiography by using carbon dioxide as contrast agent in digital subtraction angiography technique. These were diagnostic pelvis-leg angiographies (n = 106) with simultaneous consecutive interventional radiologic therapy in 68 cases. In 19 dialysis access fistulas 11 angioplasties were performed in the same session. In 5 cases of renal allografts no interventional radiologic therapy was necessary. For CO2 application an electronic controlled special injector was used. Carbon dioxide has a number of advantages: no adverse reactions, nonallergenic and can be used several times without increasing risks and is cost-saving. CO2 angiography is a sensitive method, for detection vessel wall processes below the diaphragm. It can replace conventional angiography.

Angiography, Digital Subtraction↗
PubMed1996

[In vitro studies on pulsed laser angioplasty in liquid and gaseous medium].

PURPOSE: In a vascular model the mechanisms of a pulsed dye laser working in a liquid and a gaseous environment was tested and documented by means of a high-speed camera. METHODS: The pulse application (630 nm wavelength) on a target of calcified arterial plaque material was detected at intervals of 20 microseconds up to 800 microseconds total time. RESULTS: In water the laser beam created a cavitation bubble which expanded from 0 to 450 microseconds from a radius 0 to 3 mm and collapsed afterwards. The average expansion velocity of the bubble was 80 m/s in the first 20 microseconds and the resulting velocity of the tube model wall was 10 m/s. Compared with gaseous atmosphere there was no bubble and consecutively no wall stress. CONCLUSION: It is obvious that laser angioplasty causes wall stress and destruction of different vascular layers. This might be the initial stimulation for restenosis. In gaseous atmosphere laser angioplasty should be more protective.

Angioplasty, Laser↗
PubMed1996

[Carbon dioxide as an alternative contrast medium in peripheral angiography].

A closed gas pressure pistol was used in 50 patient CO2 angiography as a supplementary method to conventional injection with liquid contrast medium. These were diagnostic pelvis-leg angiographies (n = 36), therapeutic angiographies (n = 8), haemodialysis fistulas (n = 3), suspected stenosis of a renal transplant artery (n = 1) and suspected renal artery stenosis (n = 1). 246 renal angiography series were performed with CO2. Dosages varied in accordance with the imaged vascular area between 10 ccm;(shunt imaging) and up to 100 cm3 (pelvis-leg angiography), at pressures between 400 mbar in case of haemodialysis fistulas up to 2000 mbar in the pelvis-leg area. Short-term feeling of fullness and even nausea were accompanying symptoms in 4 patients. The image quality was slightly inferior to that of conventional contrast medium images due to an elevated signal-to-noise ratio. Injector-monitored CO2 angiographies enabled imaging of the distal aorta or of peripheral vascular sections, imaging of the upper extremity and presentation of kidney transplants in patients with a relative or absolute contraindication to iodised contrast media.

Angiography↗
PubMed1996

[Indications and results of surgically treated, with temporary vena cava filter managed patients].

Heavily injured patients, patients who underwent operations on pelvis, hips, abdomen or malignoma surgery, as well as gynaecology patients suffering from malignoma or previous deep femoral vein thrombosis in connection with pregnancy or obesity are at risk to suffer from pulmonary embolism with potentially lethal course. In a retrospective study we evaluated the advantage of the prophylactic use of temporary vena cava filters and their side effects. The indications were 18 cases of surgery, with known iliacal vein or cava thrombosis, 3 cases of pregnancy thromboses, and 1 high-dose heparinisation after acute pulmonary embolism without lysis. Additionally a postoperative lysis therapy was performed due to a life-threatening pulmonary embolism in 1 patient. 1 Cook filter (transfemoral), 3 Angiocor filters (transbrachial), and 19 Antheor filters (3 transjugular, 5 transfemoral, 11 transbrachial) were implanted. In these patients no clinically visible pulmonary embolism occurred under therapy, 3 thrombi were detected in the filter. Complications were caused either by the underlying therapy alone (1 lethal outcome of abdominal aortic aneurysm surgery), by the combination of therapy and cava filter implantation (1 case of arm haematoma, 1 ascending thrombosis) or by filter implantation alone (2 cases of v. subclavia thrombosis, 1 dislocation, 1 basket rupture). Since temporary cava filters have no secondary complications per se, their use seems justified as long as there is strict indication including presence of iliacal vein or cava thrombosis and risk of thrombi mobilisation.

Abdominal Neoplasms↗
PubMed1995

Expression and fate of the nuclearly encoded subunits of cytochrome-c oxidase in cultured human cells depleted of mitochondrial gene products.

Synthesis, import, assembly and turnover of the nuclearly encoded subunits of cytochrome-c oxidase were investigated in cultured human cells depleted of mitochondrial gene products by continuous inhibition of mitochondrial protein synthesis (OP- cells). Immunoprecipitation after pulse labeling demonstrated that the synthesis of the nuclear subunits was not preferentially inhibited, implying that there is no tight regulation in the synthesis of mitochondrial and nuclear subunits of mitochondrial enzyme complexes. Quantitative analysis of the mitochondrial membrane potential in OP- cells indicated that its magnitude was about 30% of that in control cells. This explains the normal import of the nuclearly encoded subunits of cytochrome-c oxidase and other nuclearly encoded mitochondrial proteins into the mitochondria that was found in OP- cells. The turnover rate of nuclear subunits of cytochrome-c oxidase, determined in pulse-chase experiments, showed a specific increase in OP- cells. Moreover, immunoblotting demonstrated that the steady-state levels of nuclear subunits of cytochrome-c oxidase were severely reduced in these cells, in contrast to those of the F1 part of complex V. Native electrophoresis of mitochondrial enzyme complexes showed that assembly of the nuclear subunits of cytochrome-c oxidase did not occur in OP- cells, whereas the (nuclear) subunits of F1 were assembled. The increased turnover of the nuclear subunits of cytochrome-c oxidase in OP- cells is, therefore, most likely due to an increased susceptibility of unassembled subunits to intra-mitochondrial degradation.

Biological Transport↗
PubMed1995

[The importance of sonography before laparoscopic cholecystectomy].

The increasing use of minimally invasive techniques for the treatment of symptomatic cholecystitis requires exact preoperative diagnosis. The significant sonographic findings are stones in the biliary system or indirect evidence of stones, consisting in dilatation of the bile duct to more than 10 mm, as well as free mobility of the abdominal wall to exclude peri-umbilical adhesions. Amongst 100 patients who had laparoscopic cholecystectomies there were 7 with bile ducts wider than 10 mm. In two of these cases calculi could also be demonstrated. ERCP was performed on the remaining five and in 3 of these stones were seen. Peri-umbilical adhesions were seen in 6 Patients, resulting in alternative placing of the incision. The sonographic findings which are of relevance to the surgeon were analysed in these 100 cases. A standardised examination protocol is an important feature for proper patient selection.

Adolescent↗
PubMed1995

[First experiences with temporary vena cava filters].

AIM: For prophylactic measures we used 3 different temporarily insertable vena cava filters. MATERIAL AND METHODS: In 49 patients we inserted 12 Cook-filters (6 transjugular, 6 transfemoral), 11 Angio-cor-filters (1 transjugular, 10 transbrachial), 26 Antheor-filters (1 transjugular, 1 transfemoral, 24 transbrachial). 35 patients underwent a lysis therapy, 11 a major operation of the pelvis, and 3 patients a Caesarean section. RESULTS: No patient suffered from a clinically significant pulmonary embolism after filter insertion, but complications occurred caused by the basic therapy (1 lethal abdominal aortic aneurysm operation, 1 cerebral bleeding, 2 retroperitoneal haematomas, 2 streptokinase fever reactions, 1 compartment syndrome, 1 macro-haematuria) or by therapy joined with the filters insertion (2 groin haematomas, 2 haematomas of the bend of the elbow, 2 subclavian vein thrombosis, 1 catheter dislocation, 1 infection, 1 air embolism, 1 break of a leg of the filter basket). CONCLUSION: Temporary vena cava filters are highly efficient in preventing pulmonary embolism, but the side-effects show that they should only be inserted in patients with known deep vein thrombosis and a high risk treatment of the underlying disease.

Evaluation Studies as Topic↗
PubMed1995

[Normal variation of arterial liver supply in mesenterico-celiacography].

Progress in operative techniques in surgery of the upper abdomen necessitates extensive preoperative diagnostic studies. Mesenterico-coeliacography along with CAT-SCAN form the basis for effective operative planning. In the angiography, the clinician is often confronted by variations in the arterial supply of the liver. These variations of the norm which are scarcely mentioned in anatomical textbooks must be carefully taken into consideration by the surgeon. In order to clarify the operative significance of these variations, we have conducted a retrospective study of the angiographies of the truncus coeliacus as well as of the arteria mesenterica superior. We found variations in 25.5% of 204 angiographies. The incidence of deviant and accessory hepatic arteries was 33.8% and of variations in the truncus coeliacus was 6.7%. These variations of the norm are discussed as to clinical and embryological aspects.

Angiography↗
PubMed1995

[Doppler ultrasound monitoring during vascular interventions].

Doppler ultrasound examination as diagnostic device in angiology yields only discontinuous information on flow velocities in vessels during insonation with hand-held probes. Continuous insonation and therefore determination of flow velocities in arteries are necessary to evaluate flow disturbances and changes of flow velocities during radiologic invasive interventions, i.e. implantation of stents, during percutaneous transluminal angioplasty therapy or local lysis. This modification of Doppler ultrasound examination is already used in neurosurgery for permanent monitoring of flow velocities in large brain vessels in one or both hemispheres during therapy. In our institute we developed a probe holder device to fix a miniature Doppler ultrasound probe (8-MHZ pulsed-wave probe) on the skin surface. Therefore continuous insonation during the manipulations is easy to realize. Information about complications such as occlusions, thrombi, emboli and changes in flow velocity is immediately present on the screen. We have monitored 40 patients during radiologic interventional therapy in arteries of the lower limb. Complications during the interventions were detected immediately and could be corrected.

Adult↗
PubMed1995

[Digital picture archiving, processing and communication in diagnostic imaging with a Siemens Network (SIENET): initial results].

The concept of Picture Archiving and Communication System (PACS) in digital imaging offers substantial advantages: better data security, faster access to archived images, simultaneous availability of images at different sites, minimal space demand for archive medium, retrospective image post-processing opportunities and lower costs resulting from reduced film consumption and length of stay. However, practical experiences concerning reliability and efficiency of real PAC networks in radiological departments have to be made yet in order to improve network structure, software design and hardware performance. The ongoing stepwise installation and test of a Siemens PACS (SIENET) at the Department of Radiology at the Medical University of Lübeck will support the introduction of PACS concept into radiological practice.

Computer Communication Networks↗