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Biomedical subjects

V Rohde

Publications and source records attributed to V Rohde.

At least 55 records · Page 3Linked to original sources
PubMed2000

Removal of adherent ventricular catheters by a modified sheath introducer system: technical note.

BACKGROUND/PURPOSE: A series of technical notes has been dedicated to the removal of retained intracranial shunt catheters, among which the intraluminal cautery proved to be the most accepted technique. However, several reports showed that these techniques still harbor potentially serious complications. METHODS: In this technique, a modified plastic sheath introducer system is passed over the retained ventricular catheter. While advancing the tube along the longitudinal axis of the catheter, circular movements of the tube around the longitudinal axis of the catheter are performed, allowing the tube to act as a spherical knife cutting the ingrown choroid plexus or ependymal adhesions. RESULTS: There were no procedure-related complications in any of the 9 patients treated by the technique described. The procedure proved to be easy and effective in all cases. In addition, in case a new ventricular catheter was needed at the same site, it could be placed via the same tube. CONCLUSIONS: The technique described seems to be an easy, safe, and effective alternative to other techniques for removal of retained ventricular catheters. However, considering the limited number of patients treated with the technique described and the great number of patients treated by the widely accepted intraluminal cautery, one cannot claim the one technique as superior to the other at this stage.

Cardiac Catheterization↗
PubMed2000

Virtual placement of frontal ventricular catheters using frameless neuronavigation: an "unbloody training" for young neurosurgeons.

OBJECTIVE: To evaluate virtually the reliability of freehand puncture of the anterior horn of the lateral ventricle and to provide realistic, but unbloody training for young neurosurgeons. METHODS: Virtual placement of ventricular catheters was performed repeatedly by neurosurgical doctors and thereafter controlled by neuronavigation. With the help of a frameless stereotactic navigation device they virtually had to hit the anterior horn of the lateral ventricle on the MRI of 29 brains with normal ventricular sizes and 60 pathological ventricles, respectively. The catheter placement was simulated using the pointer of the navigation system (EasyGuide Neuro). The monitor screen was blinded, so that on-line control was impossible. Virtual elongation of the pointer tip was performed on the workstation and the position of the virtual catheter was evaluated on a printout. RESULTS: Virtual freehand catheter placement was performed 145 times into the MRIs of the normal brains. In 66 cases (45%) the site of the catheter tip was judged as accurate as shown by the navigation system. No difference concerning the number of correctly placed catheters was observed when comparing more and less experienced doctors. The results in the 60 pathological MRIs of patients differed with respect to the size of the ventricles: in narrow ventricles an accurate placement succeeded in 7 of 22 cases (32%), moderately enlarged ventricles were accurately hit in 15 out of 32 cases (46%) and wide ventricles in 5 of 6 attempts (83%), respectively. CONCLUSION: This setup is a simple, practicable tool for neurosurgical education. The virtual freehand placement of ventricular drains controlled by neuronavigation provides an unbloody training of a routine neurosurgical procedure in a realistic setting without the risk of injuring a patient. Neuronavigation systems can serve therefore as a link between learning from observation and handling the real situation.

Adolescent↗
PubMed2000

Anomalies and variants of the endoscopic anatomy for third ventriculostomy.

OBJECTIVE: Endoscopic third ventriculostomy (ETV) is an alternative to shunt placement in occlusive hydrocephalus. The negative impact of anatomic anomalies and variants on ETV have been sporadically reported but not yet investigated systematically. Therefore, the objectives of the present study are 1) to evaluate the frequency of endoscopic anatomic anomalies of the ventricular system, 2) to define their potential to complicate the procedure and to compromise the surgical results, and 3) to investigate the value of preoperative magnetic resonance (MR) imaging for their detection. METHOD: The video recordings, the operative reports, and the preoperative MR images of 25 hydrocephalic patients who underwent ETV were reviewed. The surgical results were classified into completed and successful, completed, but failed, and unsuccessfully attempted ETV and were correlated with the absence or presence of anatomic variants. RESULTS: In 9 of the 25 patients, 10 anatomic anomalies or variants, respectively, were identified, accounting for an incidence rate of 36%. The single most common anatomic anomaly was a thickened third ventricular floor in 4 patients. Anatomic variants extended the operation time (n = 6), increased the stretching of floor and walls of the third ventricle during perforation (n = 4), were related to minor arterial bleeding (n = 3), and obscured the visual control of the basilar artery (n = 2). In 5 of the 9 patients, ETV was completed and successful, but in 2 patients, ETV was finally abandoned, and in an additional 2 patients, ETV was completed, but failed to cure the symptoms of hydrocephalus. In contrast, ETV was completed and successful in all 16 patients with normal anatomy. All anatomic anomalies had been detectable on preoperative MR imaging, with the exception of the thickened floor of the third ventricle. CONCLUSION: Anatomic anomalies are a frequent finding during ETV. Successful perforation and control of the hydrocephalus correlates with the absence of anatomic anomalies. Most anatomic variants have the potential to increase the operative risk. With the exception of the thickened third ventricular floor, MR imaging allows us to identify all anatomic anomalies preoperatively, and enables the neurosurgeon to weigh the operative risk in a patient with an anatomic anomaly against the chance to perform ETV successfully.

Adolescent↗
PubMed2000

Frameless stereotactically guided catheter placement and fibrinolytic therapy for spontaneous intracerebral hematomas: technical aspects and initial clinical results.

OBJECTIVE: Frame-based stereotactic puncture and catheter placement followed by fibrinolytic therapy and drainage is one treatment option in the management of spontaneous intracerebral hemorrhage (sICH). This minimally invasive procedure could even be simplified by frameless stereotaxy. The authors present their experiences with frameless stereotactic image-guided catheter placement for lysis and drainage of sICH, with emphasis on technical aspects. METHOD: In 27 patients with sICH, an infrared-based frameless stereotactic device was used for selecting trajectory and target point of hematoma drainage. A trajectory along the main axis of the hematoma was considered to be optimal for fibrinolytic therapy. An articulated arm served to maintain the predetermined trajectory during surgery and to guide catheter advancement. Clot lysis with recombinant tissue plasminogen activator (rt-PA) was initiated after radiological confirmation of correct catheter positioning. RESULTS: In all cases, selection of the optimal trajectory was not restricted by the frameless stereotactic device. In 25 of the 27 patients, the catheter was placed accurately along the predetermined trajectory into the target point. In two patients, the catheter was positioned at the lateral margin of the hematoma, excluding fibrinolytic therapy in one case. In 24 of 27 patients, the mean hematoma volume could be reduced from initially 52 ml to 17 ml in an average of two days. Hematoma enlargement following rt-PA injection was observed in two patients. Further complications were culture negative pleocytosis of cerebrospinal fluid in two and meningitis in one patient. CONCLUSION: Hematoma puncture and catheter placement for fibrinolytic therapy could be achieved with high accuracy and safety using frameless stereotaxy. This method allows unrestricted trajectory selection with catheter positioning along the main hematoma axis. Further studies are required to investigate if frameless stereotactic puncture and clot lysis could contribute to improve the outcome of patients with sICH.

Adult↗
PubMed2000

Experimental acute intracerebral hemorrhage. Value of MR sequences for a safe diagnosis at 1.5 and 0.5 T.

PURPOSE: To determine the detectability of intracerebral hematomas with MR imaging at 1.5 T and 0.5 T with fluid attenuated inversion recovery turbo spinecho (FLAIR) and gradient-echo sequences. MATERIAL AND METHODS: Twenty-seven intracerebral hematomas were created in 25 piglets by injection of venous blood into the brain through a burr hole. All were imaged with T2*-weighted gradient echo sequences (fast field echo, FFE), T2-weighted fluid attenuated inversion recovery turbo spin-echo sequences (FLAIR), T2-weighted turbo spin-echo (TSE) and T1-weighted spinecho sequences. Follow-up was performed on the 2nd, 4th and 10th postoperative days. Ten animals were additionally investigated with similar sequences at 0.5 T. Histologic correlation was obtained in all cases. RESULTS: T2* FFE sequences detected all acute intracerebral hematomas and demonstrated the size correctly at 1.5 T and 0.5 T. The conspicuity was better at 1.5 T. FLAIR sequences were unreliable in the hyperacute phase at 1.5 T: However. subarachnoid and intraventricular extension was best appreciated with FLAIR images. T2 TSE images were incapable of detecting paraventricular and subarachnoid hemorrhages, but clearly demonstrated intracerebral blood in other locations. TI-weighted images were insensitive to hemorrhage in the acute state but very useful in subacute and chronic hematomas. CONCLUSION: The safe and reliable diagnosis of intracerebral hemorrhage is probably possible with MR imaging at 1.5 T and 0.5 T even of hematomas less than 90 min old, but requires the application of at least FLAIR, T2* FFE and T1 sequences and is therefore time consuming.

Acute Disease↗
PubMed2000

Prospective analysis of bedside percutaneous subdural tapping for the treatment of chronic subdural haematoma in adults.

OBJECTIVES: Although there is general agreement that surgery is the best treatment for chronic subdural haematoma (CSDH), the extent of the surgical intervention is not well defined. METHODS: The less invasive surgical technique of bedside percutaneous subdural tapping and spontaneous haematoma efflux after twist drill craniostomy under local anaesthesia was prospectively analysed in 118 adult patients, 99 with unilateral and 19 with bilateral CSDH. RESULTS: The mean number of subdural tappings was 3.2. Ninety two of the patients with unilateral CSDH were successfully treated by up to five subdural tappings, 95% of the patients with bilateral CSDH were successfully treated by up to 10 subdural tappings. The mean duration of inpatient treatment was 12 days. In 11 patients (9%) the treatment protocol had to be abandoned because of two acute subdural bleedings, two subdural empyemas, and seven cases of insufficient haematoma efflux and no neurological improvement. The only significant predictor for failure of the described treatment protocol was septation visible on preoperative CT. CONCLUSIONS: The described therapy protocol is-apart from a purely conservative treatment-the least invasive presently available surgical technique for treating chronic subdural haematoma. Its results are comparable with other modern treatment protocols. Thus, it can be recommended in all patients as a first and minimally invasive therapy, especially in patients in a poor general condition. Patients with septation visible on preoperative CT should be excluded from this form of treatment.

Adult↗
PubMed2000

Expression of the human telomerase reverse transcriptase is not related to telomerase activity in normal and malignant renal tissue.

In this study, the association between telomerase activity and the expression of the human telomerase subunits human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) in paired neoplastic and normal renal tissue samples was investigated. Reverse transcription (RT)-PCR on 20 tumor nephrectomy samples revealed that hTR was constitutively expressed both in cancer and normal tissue samples, independent of the telomerase activity status. Remarkably, using in situ hybridization, the expression levels of hTR were found to be markedly higher in the normal tissue than those in the tumors. Expression of hTERT mRNA by RT-PCR was observed in 90% of the cancer samples and, notably, also in 75% of the corresponding normal renal tissue samples. Because all of the normal tissue samples and some of the tumor samples were shown to be telomerase negative, our findings suggest that hTERT mRNA expression is not sufficient for telomerase enzyme activation. Furthermore, semiquantitative RT-PCR revealed equal or even higher hTERT mRNA expression levels in the telomerase-negative normal samples than in the corresponding cancer samples with telomerase activity, contradicting the assumption that a certain threshold level of hTERT mRNA is required for telomerase activation at least in renal tissue. It seems more likely, that other mechanisms, such as posttranscriptional modification of hTERT or inactivation of telomerase inhibitors, are involved in the acquisition of enzyme activity.

Carcinoma, Renal Cell↗
PubMed1999

Biosynthesis of phytochelatins in the fission yeast. Phytochelatin synthesis: a second role for the glutathione synthetase gene of Schizosaccharomyces pombe.

By complementation screening of a cadmium-sensitive Schizosaccharomyces pombe mutant deficient in phytochelatin synthesis, but with 44% of the wild-type glutathione content, we cloned a DNA fragment involved in phytochelatin synthesis. Sequence analysis revealed that it encodes the second enzyme involved in glutathione (GSH) biosynthesis, glutathione synthetase (GSH2) (E.C.6.3.2.3, Wang and Oliver, 1997). The mutant allele shows a single base-pair exchange at the 3' end of the reading frame leading to a single amino acid change from glycine to aspartate. This mutation leads to a significant reduction of phytochelatin synthesis, whereas glutathione synthesis is impaired to a far lesser extent. Complementation with the Arabidopsis thaliana GSH2 cDNA led to a partial restoration of phytochelatin synthesis. These data strongly suggest that the GSH2 gene encodes a bifunctional enzyme that is able to catalyse both the synthesis of GSH by adding glycine to the dipeptide (gammaGlu-Cys) and the synthesis of phytochelatins. The sequence has been submitted to EMBL, Accession No. Y08414.

Alleles↗
PubMed1999

Comparative genomic hybridization reveals DNA copy number gains to frequently occur in human prostate cancer.

BACKGROUND: Despite intensive studies over many years, there is only limited knowledge on the genetic changes underlying the development and progression of prostate cancer. No specific prostate carcinoma-related genetic event has yet been identified. METHODS: In order to gain an overall view of regional chromosome gains and losses, comparative genomic hybridization (CGH) was used on a series of 16 prostate adenocarcinomas. Five benign prostate hyperplasia (BPH) samples were also evaluated. RESULTS: Using CGH, chromosome alterations were observed in 81% of the prostate carcinomas analyzed. Gains of DNA copy numbers were found as the predominant imbalance, with chromosomes 3q (56%), 12q (56%), 8q (50%), Xq (50%), 4 (44%), 6q (44%), 5 (38%), 7q (38%), 9p (38%), and 13q (31%) being most frequently involved. Whereas DNA copy number gains comprised the whole chromosome or almost a whole arm of chromosomes 4, 5, 6, 9, and 13, the minimal overlapping regions on the other chromosomes were mapped to 3q25-q26, 8q21-q22, 12q13-q21, 7q31, and Xq22-q25. High-level amplifications were not found. Other chromosomes with nonrandom gains or losses of DNA sequences were discovered. The five BPH samples were found to be normal. CONCLUSIONS: Amplification events at different chromosomal sites seem important in prostate cancer development. A new chromosome region with DNA copy number gains was identified on 12q, while other regions on 3q, 7q, 8q, and Xq were confirmed or narrowed down, indicating a possible role of known or putative protooncogenes in these regions for prostate cancer growth. Our low detection rate of DNA losses may to some part be explained by CGH immanent technical limitations.

Adenocarcinoma↗
PubMed1999

Functional outcome after aneurysmal subarachnoid hemorrhage.

The introduction of the operating microscope, the principle of early surgery, specialized intensive care units, the calcium antagonist nimodipine, the sophisticated pre- and postoperative management and an aggressive antiischemic pharmacological management have substantially reduced morbidity and mortality after aneurysmal subarachnoid hemorrhage (SAH). In spite of this progress, many patients after rupture and surgical repair of an intracranial aneurysm exhibit substantial cognitive deficits and emotional problems although their neurological outcome was rated as good according to the Glasgow Outcome Scale (GOS = I). Therefore, a comprehensive neuropsychological examination is called for in order to evaluate the factual functional outcome after SAH. Neither focal brain damage associated with aneurysm location nor surgery but the hemorrhage itself and related events can be regarded as the most important causal factors for the late result after SAH. In contrast to the mild permanent effects of aneurysm surgery, the initial bleeding itself seems to have substantial lasting adverse neurobehavioral effects after. In concordance with other authors our own data stress the strong predictive power of the bleeding pattern such as the presence of intraventricular and/or intracerebral blood on the functional outcome after aneurysmal SAH.

Aneurysm, Ruptured↗
PubMed1999

Prediction of the post-comatose motor function by motor evoked potentials obtained in the acute phase of traumatic and non-traumatic coma.

OBJECTIVE: To define the value of electrically elicited motor evoked potentials (MEP), obtained during the initial phase of the coma, for correct prediction of the post-coma motor status. METHODS: Fifty-two patients were investigated by MEP within 72 hours after onset of the coma. It was the aim to correlate the MEP findings to the motor function two months after coma onset. RESULTS: Three patients with normal MEP showed no post-coma motor deficit. In 21 patients, a bilateral, symmetric prolongation of the central motor conduction time (CMCT) was registered. Eighteen of these 21 patients (86%) showed a normal post-coma motor status. In 28 patients, unilaterally absent evoked potential, or unilaterally prolonged CMCT, or bilaterally prolonged CMCT with significant difference in each hemisphere were observed. A post-coma contralateral paresis was found in 25 of these 28 patients (89%). That paresis was functionally important in 15 patients (54%) and functionally unimportant in 13 patients (46%). CONCLUSION: We identified certain MEP patterns (unilateral extinction of the evoked potential, unilateral, bilateral prolongation of the CMCT with significant "side" difference), which indicated a pyramidal tract lesion and a post-coma motor deficit with an accuracy of 89%. This refers to the motor results, which may not be the final post-coma motor results which are usually assessed six months after the coma onset. The MEP changes did not allow one to predict the severity of the paresis. The accuracy of prediction of a motor deficit increased from the MEP finding of unilaterally prolonged CMCT to the MEP finding of unilateral extinction of the potential. The most common finding, bilateral central motor slowing without significant "side" difference, did not indicate a post-coma paresis in 86%, leading to the assumption, that bilateral, symmetrical prolongation of the CMCT was not caused by lesions of the descending motor pathways, but by the drugs administered for treating the comatose patient. In conclusion, MEP allows one to predict the presence of a post-coma motor deficit with a high degree of accuracy already in the initial phase of coma, but MEP fails to predict the severity of that deficit.

Acute Disease↗
PubMed1999

Detection of adeno-associated virus in human semen: does viral infection play a role in the pathogenesis of male infertility?

OBJECTIVE: To evaluate the occurrence of adeno-associated virus (AAV) DNA and/or human papillomavirus (HPV) DNA in the semen of infertile men as a possible factor in the pathogenesis of male infertility. DESIGN: Descriptive pilot study. SETTING: University-based diagnostic and research laboratory. PATIENT(S): Semen specimens were collected from 30 men with diagnosed infertility and from 8 control subjects. INTERVENTION(S): Diagnostic spermiograms were made and the semen specimens were separated into seminal fluid, nonspermatozoal cells, and spermatozoa using a Ficoll gradient technique. MAIN OUTCOME MEASURE(S): The presence of AAV and HPV DNA in the different fractions of the ejaculates from the infertile men and the control subjects was detected by polymerase chain reaction. Semen quality was analyzed according to World Health Organization guidelines. RESULT(S): Adeno-associated virus DNA was detected in 30% (9/30) of the ejaculates from the infertile men. No AAV DNA was found in the ejaculates from the 8 control subjects. In 8 of 9 samples, AAV DNA could be found only in the spermatozoal fraction of the specimen. Seven of 9 semen specimens that contained viral DNA also demonstrated oligoasthenozoospermia. Both AAV and HPV DNA was found in the spermatozoal fraction of 3 of 30 specimens. CONCLUSION(S): The data demonstrate for the first time the occurrence of AAV infection in human semen. Sperm motility seems to be affected by the presence of AAV.

Adult↗
PubMed1999

Modification of a mechanical twist drill trephine for craniostomy in trauma patients.

A commercially available mechanical twist drill system was modified and evaluated in 35 craniotomies for frontal ventriculostomy in 31 trauma patients. The modified mechanical twist drill enabled faster and seemingly easier and safer craniotomy. It can be used as a safer alternative to common mechanical twist drill trephines, and is particularly recommended in difficult emergency conditions.

Adult↗
PubMed1999

Fibrinolytic treatment of intraventricular haemorrhage preceding surgical repair of ruptured aneurysms and arteriovenous malformations.

Previous studies have indicated that intraventricular administration of tissue-type plasminogen activator (TPA) might improve the prognosis of patients with intraventricular haemorrhage (IVH). In aneurysmal IVH, fibrinolytic treatment was always preceded by surgical repair of the aneurysm, since the risk of recurrent haemorrhage from a non-occluded aneurysm was estimated to be high. We reviewed a series of patients with IVH secondary to ruptured aneurysms (n = 4) or arteriovenous malformation (AVM; n = 1) who underwent emergency intraventricular administration of TPA before repair of the bleeding source. Fibrinolysis resulted in rapid decrease of haematoma volume and of ventricular dilatation, and prevented ventricular catheters from becoming obstructed. No intracranial haemorrhages or other complications occurred. The results suggest that the presence of recently ruptured aneurysms or AVM is not necessarily a contraindication for intraventricular administration of TPA. The potentially life saving benefits might outweigh the inherent risks of recurrent haemorrhage in carefully selected patients with massive IVH, in whom ventricular distension, periventricular brain compression, obstruction of CSF flow, and elevated ICP appear to be major determinants for the outcome.

Adult↗
PubMed1999

Treatment of erectile dysfunction with external vacuum devices.

In a retrospective study, the medical and psychological outcome of the use of external vacuum devices in the treatment of erectile dysfunction in 190 patients was evaluated, using a questionnaire and a clinical examination. 110/190 patients (57.8%) answered the questionnaire. 22/110 patients (20%) rejected the device primarily and 34/110 (30.9%) after a period of up to 16 weeks (primary rejection rate 50.9%). A secondary drop-out rate of 8/110 (7.3%) was observed after an intermediate time of 10.5 months. 46/110 (41.8%) patients were long-term users (median 27.6 months, range 7-70 months). Long-term users were mainly patients who did not respond to intracavernosal pharmacotherapy. In the group of long-term users, 98% of patients and 85% of their partners were satisfied with the vacuum therapy. Complications were minor (hematoma 9.8%; skin injury 2.2%), 69.8% of long-term users never had problems with the device. 74% of users reported regular orgasm. Vacuum therapy is a safe and effective non-invasive treatment of erectile dysfunction with a limited primary acceptance and low drop-out rates in long-term follow-ups.

Adult↗
PubMed1999

Focal intratumoral heterogeneity for telomerase activity in human prostate cancer.

PURPOSE: The value of telomerase activity as a marker in clinical decision-making is closely related to how representative the analysis of a small tumor sample is for the whole tumor. We therefore evaluated the intratumoral distribution pattern of telomerase activity in prostatic carcinomas. MATERIALS AND METHODS: From 50 prostate cancer patients treated with radical prostatectomy, telomerase activity was determined using the telomeric repeat amplification protocol (TRAP assay). Comparative analysis of at least two separate cancer areas from a single tumor was performed in 42 cases. RESULTS: Telomerase activation has been demonstrated in 90% of the prostatic carcinomas. Focal intratumoral heterogeneity was found in 38.1% of the tumors with at least two different areas examined. Telomerase positivity of all samples from one given tumor was detected in 50%, telomerase negativity of all samples in 11.9%. A heterogeneous telomerase activity pattern was more frequently detected in tumors with a Gleason score < or = 7 than in those with a Gleason score > 7. Furthermore, there was an increase in the proportion of homogeneously telomerase-positive tumors with increase in severity of the Gleason score. The differences reached statistical significance. Telomerase activity was also detected in non-cancerous prostatic tissue samples. CONCLUSIONS: Telomerase activation is nearly ubiquitous in prostatic carcinomas, although a heterogeneous telomerase activity pattern within tumors might produce a false-negative result in the telomerase activity assay. This limits the value of telomerase activity assays for diagnostic means. There is evidence for a shift from telomerase-negative prostate cancer tissue toward telomerase positivity during the progression process of prostate cancer. The relatively high proportion of telomerase-positive nonmalignant prostatic tissue samples argues against cancer-specificity of telomerase activation.

Humans↗