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Biomedical subjects

S Ernst

Publications and source records attributed to S Ernst.

At least 37 records · Page 2Linked to original sources
PubMed2001

[MRI with cerebrospinal fluid measurement before and after endoscopic ventriculostomy and aqueductal stenosis].

PURPOSE: Evaluation of MR imaging and CSF flow measurement for planning and follow-up of neuroendoscopic third ventriculostomy in occlusive triventricular hydrocephalus. METHOD: 17 patients with occlusive hydrocephalus due to idiopathic or neoplastic aqueductal stenosis were examined before and after surgery with cardiac-gated T2-weighted and cardiac-gated phase contrast cine sequences. The visibility of anatomic structures and the patency of the ventriculostomy were evaluated. RESULTS: In all 17 patients, the relevant anatomic structures were visible. The cine sequence demonstrated occlusion of the aqueduct and patency of the ventriculostomy in all cases, even in patients with doubtful clinical patterns. CONCLUSIONS: MR imaging with additional cardiac-gated cine sequences allows exact preoperative diagnosis of occlusive hydrocephalus as well as patient selection and planning for endoscopic third ventriculostomy. Non-invasive follow-up, especially in patients with a doubtful clinical pattern, is possible.

Adolescent↗
PubMed2001

Correlation between crash severity, injury severity, and clinical course in car occupants with thoracic trauma: a technical and medical study.

BACKGROUND: The crash mechanisms and clinical course of car occupants with thoracic injury were analyzed to determine prognostic factors and to create a basis for injury prophylaxis. METHODS: A technical and medical investigation of car occupants with a thoracic injury (Abbreviated Injury Scale-thorax [AIS(THORAX)] > or = 1) at the scene of the crash and the primary admitting hospital was performed. RESULTS: Between 1985 and 1998, 581 car occupants sustained a thoracic injury. Mean parameter values were as follows: AIS(THORAX), 2.5; Hannover Polytrauma Score (PTS), 21.4; Injury Severity Score (ISS), 24.2; Delta-v, 49.6 km/h (30.8 mph); and extent of passenger compartment deformation (DEF) (scale, 1--9), 4.0. In 19% (n = 112) of patients involved, the clinical course was evaluated: AIS(THORAX), 2.5; PTS, 20.0; ISS, 19.3; Delta-v, 50.1 km/h (31.1 mph); DEF, 3.9; intensive care unit time, 8.3 days; ventilation time, 5.7 days; and hospital stay, 15.3 days. In the groups with higher AIS(THORAX), ISS, PTS, and intensive care unit and ventilation time, higher Delta-v and DEF occurred. In patients with longer hospital stay, higher Delta-v, but no difference in DEF occurred. CONCLUSION: The injury severity and the clinical course demonstrated a positive correlation with the crash severity. Therefore, our technical accident analysis allows prediction of the severity of injury and the clinical course. It may consequently serve as a tool for development of more sophisticated injury prevention strategies and may improve passive car safety.

Abbreviated Injury Scale↗
PubMed2000

[Effect of monaural deprivation on maturation of the auditory pathway in the Mongolian gerbil (Meriones unguiculatus)].

Several investigations prove that monaural acoustic deprivation induces detrimental changes in the auditory pathway. So far the major interest focused on degenerative processes on the deprived side, while effects on the contralateral untreated side were not taken into consideration. This ontogenetic study investigates effects of early monaural acoustic deprivation on the functional development of the acoustically evoked auditory brainstem response (ABR) in the Mongolian gerbil. Young gerbils were deafened by a single intracochlear application of neomycin sulfate. The ABR development on the contralateral side differed in a late developmental period from that of normally hearing animals. These changes persisted until adulthood. Between day 55 and day 90 a significant 5 dB decrease of the ABR thresholds and a significant shortening of the interpeak latency II-V occurred. The results confirm that a complete monaural deprivation during the sensible or critical period leads on the contralateral side to plastic or compensatory changes in the auditory brainstem.

Age Factors↗
PubMed2000

[Using the Mongolian gerbil (Meriones unguiculatus) as an animal model in ontogenetic cochlear implant research].

One of the problems when providing prelingually deafened children with a cochlear implant is to find the optimal moment for the implantation in order to make optimal use of the sensitive phase in the maturation of the auditory system and to achieve the maximum improvement of hearing. Ontogenetic questions can be investigated in animal experiments under controlled conditions. In the present study an animal model (gerbil, Meriones unguiculatus) was established to simulate the situation of prelingually deafened children and to examine the influence of chronic electrostimulation on the development of the auditory pathway. We used species specific sounds for chronic stimulation to simulate significance of human language in our animal modell. A daily two-hour electrostimulation during the ontogenesis of early deafened animals lead to a partial compensation of the functional degeneration of the auditory pathway, which can be observed in totally deafened animals. This animal model provides an elaborate test design which can be used in CI research for the investigation of numerous problems.

Animals↗
PubMed2000

Placebo-associated remissions in a multicentre, randomized, double-blind trial of interferon gamma-1b for the treatment of metastatic renal cell carcinoma. The Canadian Urologic Oncology Group.

OBJECTIVE: To determine the validity of using an historical maximum spontaneous regression rate (reportedly 0-1.1% in those with lung metastases after nephrectomy) in clinical trials of treatments for patients with metastatic renal cell carcinoma (RCC), as the eligibility criteria for most studies will select patients with better performance status (and thus excluding those who are unlikely to respond) and more modern staging methods would potentially reduce the number of false-positives. PATIENTS AND METHODS: A multicentre randomized,placebo-controlled, double-blind trial was recently completed in which 197 patients with metastatic RCC from 17 study centres across Canada were randomized to receive placebo or recombinant interferon gamma-1b (60 microg/m2) subcutaneously once every 7 days until disease progression. All tumour responses were validated by an independent response committee unaware of the treatment. RESULTS: The median (95% confidence interval) overall response rate (complete, CR, and partial, PR) for those on interferon-gamma was 4 (1.4-11.5)% and for those on placebo was 6 (2. 5-13.2)% (P = 0.75). In the six patients who were receiving placebo the CR and PR (three each) was considered to represent spontaneous remission. Of these six patients (aged 44-64 years) five had undergone nephrectomy, one a tumour embolization, four had clear cell carcinoma and one an adenocarcinoma, and all had regression of lung and/or lymph node metastases. CONCLUSION: The lack of efficacy of interferon-gamma in this trial underlines the importance of continued research to identify alternative therapeutic agents or combinations of agents in phase II studies. However, the threshold response rate for initiating phase III trials should be increased to 18% in the phase II trials, i.e. three times the response rate on placebo.

Adult↗
PubMed2000

Haploid plants regenerated from androgenic cell cultures of Digitalis lanata.

Androgenic callus was obtained from cold treated anthers and pollen of Digitalis lanata. The callus was mixoploid and contained haploid, diploid and tetraploid cells as shown by impulse cytophotometry. Haploid cell lines were selected by colony cloning. They were unstable and selection had to be repeated every 1-2 months. Mixoploid shoot cultures were derived from embryogenic haploid cell lines via somatic embryos. Haploid shoots were selected by explanting shoot tips. The shoots showed wide variability in cardenolide content and profile. Rooting of the haploid shoots resulted in haploid plants. These plants were smaller in size than diploid plants. Often the flowers were morphologically abnormal and showed male sterility due to crippled anthers.

Androgens↗
PubMed2000

The X-ray structure of a chitinase from the pathogenic fungus Coccidioides immitis.

The X-ray structure of chitinase from the fungal pathogen Coccidioides immitis has been solved to 2.2 A resolution. Like other members of the class 18 hydrolase family, this 427 residue protein is an eight-stranded beta/alpha-barrel. Although lacking an N-terminal chitin anchoring domain, the enzyme closely resembles the chitinase from Serratia marcescens. Among the conserved features are three cis peptide bonds, all involving conserved active site residues. The active site is formed from conserved residues such as tryptophans 47, 131, 315, 378, tyrosines 239 and 293, and arginines 52 and 295. Glu171 is the catalytic acid in the hydrolytic mechanism; it was mutated to a Gln, and activity was abolished. Allosamidin is a substrate analog that strongly inhibits the class 18 enzymes. Its binding to the chitinase hevamine has been observed, and we used conserved structural features of the two enzymes to predict the inhibitors binding to the fungal enzyme.

Acetylglucosamine↗
PubMed2000

The X-ray structure of the NAD-dependent 5,10-methylenetetrahydrofolate dehydrogenase from Saccharomyces cerevisiae.

Eucaryotes possess one or more NADP-dependent methylene-THF dehydrogenases as part of multifunctional enzymes. In addition, yeast expresses an unusual monofunctional NAD-dependent enzyme, yMTD. We report X-ray structures for the apoenzyme and its complex with NAD+ at 2.8 and 3.0 A resolution, respectively. The protein fold resembles that seen for the human and Escherichia coli dehydrogenase/cyclohydrolase bifunctional enzymes. The enzyme has two prominent domains, with the active site cleft between them. yMTD has a noncanonical NAD-binding domain that has two inserted strands compared with the NADP-binding domains of the bifunctional enzymes. This insert precludes yMTD from dimerizing in the same way as the bifunctional enzymes. yMTD functions as a dimer, but the mode of dimerization is novel. It does not appear that the difference in dimerization accounts for the difference in cofactor specificity or for the loss of cyclohydrolase activity. These functional differences are probably accounted for by minor differences within the tertiary structure of the active site of the monomeric protein.

Amino Acid Sequence↗
PubMed2000

Prevention of atrial fibrillation by complete compartmentalization of the left atrium using a catheter technique.

INTRODUCTION: Right atrial compartmentalization has been demonstrated to only reduce the number of atrial fibrillation (AF) episodes; left atrial (LA) fibrillation still occurs. METHODS AND RESULTS: We report successful LA compartmentalization resulting in isolation of all four pulmonary veins in a 51-year-old woman suffering from paroxysmal AF. Deployment of a complete encircling line resulted in dissociation of electrical activation within the isolated area from the remaining LA. Despite attempts at reinduction by pacing maneuvers inside and outside the isolated area, AF was no longer inducible. During 21-week follow-up, the patient remained in stable sinus rhythm with rare atrial extrasystoles. CONCLUSION: If reproducible, this ablation strategy could allow treatment of AF independent of suppression of any triggering event.

Atrial Fibrillation↗
PubMed1999

Modification of the substrate for maintenance of idiopathic human atrial fibrillation: efficacy of radiofrequency ablation using nonfluoroscopic catheter guidance.

BACKGROUND: Catheter ablative techniques to modify the substrate to maintain atrial fibrillation (AF) require the creation of continuous radiofrequency current-induced ablation lines. This study was designed to assess the efficacy and safety of nonfluoroscopic mapping in this setting. METHODS AND RESULTS: A total of 45 consecutive patients with idiopathic AF were studied. The first 13 underwent ablation confined to the left atrium by creating a circular line isolating the pulmonary vein ostia and a second line connecting the former with the mitral annulus. Subsequently, 12 of these patients underwent a procedure confined to the right atrium (RA), where attempts were made to create an isthmus line between the inferior vena cava and the tricuspid annulus, an anterior line connecting the tricuspid annulus with the superior vena cava, and an intercaval line between the ostia of the inferior and superior venae cavae. In the last 32 patients, only the RA approach was performed. Technical difficulties prevented the creation of the intended left atrial line pattern: all patients experienced recurrences. A 100% recurrence rate was also observed after subsequent RA ablation, despite creation of a complete line pattern in 4 of 12 patients. Of the final 32 patients, AF recurred in 94%; a complete ablation line pattern had been achieved in 18 patients (56%), 16 of whom had recurrences. CONCLUSIONS: The electroanatomically-guided creation of extended radiofrequency current lesions is technically feasible only in the RA. However, procedural success in the RA does not suppress recurrences of AF in the majority of patients.

Atrial Fibrillation↗
PubMed1999

Analysis of sperm chromosome complements before, during, and after chemotherapy.

Sperm chromosomal abnormalities were assessed in testicular cancer patients before, during, and after BEP (bleomycin, etoposide, cisplatin) chemotherapy (CT). Multicolor fluorescence in situ hybridization (FISH) analysis was employed to detect aneuploidy for chromosomes 1, 12, X, and Y, and diploidy. Sperm samples were cryopreserved and coded before analysis to facilitate "blind" analysis. Complete results at all time points was available for only one patient. A total of 60,400 sperm were analyzed: 20,004 before CT, 20,005 during CT, and 20,391 after CT. There was a significant increase in the frequency of 24,XY sperm during (0.33%) and post-CT (0.34%) compared to pre-CT (0.14%). This study suggests that there may be a significantly increased risk of chromosomal abnormalities in sperm of CT patients during and immediately post-CT, similar to that shown in animal models.

Adult↗
PubMed1999

Cricoid cartilage necrosis after arytenoidectomy in a previously irradiated larynx.

Several open and endoscopic surgical techniques are available to provide an adequate airway for patients with bilateral vocal cord paralysis. Transoral laser arytenoidectomy has repeatedly been reported to be a reliable and effective minimally invasive procedure for airway restoration. To our knowledge, there have been no previous reports of serious complications, other than poor vocal results, aspiration, and failed decannulation in individual patients, that have resulted from this intervention. We report a case in which arytenoidectomy led to severe complications and death. Prior irradiation is suspected to be a causative factor. To prevent such an outcome, we believe that operative settings should be chosen that avoid deep thermal injury of the laryngeal framework.

Arytenoid Cartilage↗
PubMed1999

Placement of Palmaz stents in malignant duodenal stenosis through a cutaneous fistula.

This is the first report of palliative percutaneous treatment of a malignant duodenal stenosis due to cancer of the pancreatic head with Palmaz stents. A 65-year-old male with a malignant tumour of the pancreatic head developed an abscess with fistular communication to the cutis. In the subsequent course of the disease, tumour growth led to a severe duodenal stenosis. To dilate the tumorous stenosis, three Palmaz stents were introduced coaxially into the duodenum percutaneously, via the preexisting fistula. A technique to pass an almost 90 degrees kink is described. Symptomatic malignant duodenal stenosis was treated by insertion of three Palmaz stents. Due to their accurately controlled passive expansion at the level of the stenosis, and the resulting good adaptation to the individual anatomical situation, they were suitable for application in the duodenum.

Aged↗
PubMed1999

Outcome and safety of transrectal US-guided percutaneous cryotherapy for localized prostate cancer.

OBJECTIVES: To assess the effectiveness and safety of ultrasound (US)-guided cryotherapy as a primary treatment for localized prostate cancer. MATERIALS AND METHODS: A prospective study of percutaneous transrectal US (TRUS)-guided cryotherapy was performed on 71 patients with T1-T3, N0, M0 prostatic cancer: 10 patients underwent two or more procedures. All cases were newly diagnosed and patients had no previous treatment for cancer. For all patients, TRUS biopsies were performed at 5-6 months. Patients were monitored at 6 weeks; 3, 6, 9, and 12 months; and twice yearly thereafter for prostate specific antigen (PSA) levels, complications, and clinical evidence of residual disease. RESULTS: Follow-up from 10 to 36 months was available for 70 of 71 patients; one patient died of unrelated disease. Initially, 10 of 69 patients had positive postcryotherapy biopsy results. After repeated treatment, nine of these 10 patients had negative biopsy results and one patient had no follow-up. Overall, 68 of 69 patients had negative biopsy results. At 1 year, 43 of 64 (67%) had an undetectable PSA level. Two patients had proven metastases. Complications include three cases with urethral sloughing requiring transurethral resection of the prostate (TURP). One patient had orchitis. Two patients had persistent incontinence, one as the result of a TURP. There was no death, acute serious morbidity, or fistula formation. Impotence was universal at 6 months, but many patients demonstrated late recovery. CONCLUSION: Cryoablation is an imaging-guided percutaneous intervention for prostate cancer that can safely yield disease-free status in a high percentage of patients with localized disease.

Adenocarcinoma↗