Search PubMed⌕ Search

Biomedical subjects

A Ernst

Publications and source records attributed to A Ernst.

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

Hearing loss after spinal and general anesthesia: A comparative study.

Hearing loss has been described after spinal anesthesia. We examined the hearing in patients before and after spinal and general anesthesia by pure tone audiometry (LdB: 125-1500 Hz; HdB: 2000-8000 Hz). Tympanic membrane displacement analysis was used to noninvasively monitor the intralabyrinthine and intracranial pressure. Eighteen patients received spinal anesthesia (G(SA)); 19 patients general anesthesia (G(GA)). Pure tone audiometry and TMD data were obtained preoperatively ((0)) and postoperatively on day 1 ((1)) and 2 ((2)). The mean threshold differences (Delta) in LdB(10) and LdB(20) were significantly different in G(SA) compared with G(GA) (DeltaLdB(10) + 0.15+/-3.07 dB vs. -1.34+/-3.77 dB, P = 0.05; DeltaLdB(20) -0.54+/-2.24 dB vs. -2.45+/-3.39 dB, P<0.01). However, there were no differences in DeltaHdB(10) between G(SA) and G(GA), but in DeltaHdB(20) (-1.40+/-3.95 dB vs -5.12+/- 6.35 dB, P = <0.01). We found a significant correlation between the magnitude of intraoperative intravascular volume replacement and low-frequency hearing loss. Tympanic membrane displacement values were not different pre- and postoperatively. Hearing was impaired after spinal and general anesthesia. Low-frequency hearing loss was correlated with intraoperative volume replacement. Tympanic membrane recordings did not reveal significant changes.

Adult↗
PubMed2000

PCR bias in ecological analysis: a case study for quantitative Taq nuclease assays in analyses of microbial communities.

Succession of ecotypes, physiologically diverse strains with negligible rRNA sequence divergence, may explain the dominance of small, red-pigmented (phycoerythrin-rich) cyanobacteria in the autotrophic picoplankton of deep lakes (C. Postius and A. Ernst, Arch. Microbiol. 172:69-75, 1999). In order to test this hypothesis, it is necessary to determine the abundance of specific ecotypes or genotypes in a mixed background of phylogenetically similar organisms. In this study, we examined the performance of Taq nuclease assays (TNAs), PCR-based assays in which the amount of an amplicon is monitored by hydrolysis of a labeled oligonucleotide (TaqMan probe) when hybridized to the amplicon. High accuracy and a 7-order detection range made the real-time TNA superior to the corresponding end point technique. However, in samples containing mixtures of homologous target sequences, quantification can be biased due to limited specificity of PCR primers and probe oligonucleotides and due to accumulation of amplicons that are not detected by the TaqMan probe. A decrease in reaction efficiency, which can be recognized by direct monitoring of amplification, provides experimental evidence for the presence of such a problem and emphasizes the need for real-time technology in quantitative PCR. Use of specific primers and probes and control of amplification efficiency allow correct quantification of target DNA in the presence of an up to 10(4)-fold excess of phylogenetically similar DNA and of an up to 10(7)-fold excess of dissimilar DNA.

Bacteria↗
PubMed2000

Mediastinal lymphadenopathy: diagnostic yield of transbronchial mediastinal lymph node biopsy with CT fluoroscopic guidance-initial experience.

PURPOSE: To determine whether the use of computed tomographic (CT) fluoroscopy to guide transbronchial needle aspiration (TBNA) of mediastinal lymph nodes can improve the diagnostic yield. MATERIALS AND METHODS: CT fluoroscopy was used to guide TBNA in 12 consecutive patients with mediastinal lymphadenopathy who had previously undergone nondiagnostic conventional TBNA. CT fluoroscopy was used to confirm the location of the biopsy needle by using a "quick-check" technique (ie, fluoroscopy was performed sparingly after needle insertion). The location of each needle, the total procedural and fluoroscopic times, and any complications were recorded. RESULTS: All CT fluoroscopic procedures were performed in less than 1 hour, and a tissue diagnosis was established in all patients. Eighteen lymph nodes with a diameter of 0.8-2.4 cm were sampled with 116 needle passes. CT fluoroscopy documented inadequate positioning in 48 of the 116 (41.3%) needle passes. Eighteen (15.5%) needles did not fully penetrate the tracheobronchial tree. Six needles (5.2%) were placed into the great vessels. Malignant disease was diagnosed in nine patients, and benign disease was diagnosed in three. The mean fluoroscopic exposure time was 20.5 seconds +/- 12.7. No pneumothoraces or substantial hemorrhage were observed. CONCLUSION: CT fluoroscopic guidance for TBNA procedures is a safe and efficient means of providing diagnostic material and should be considered for patients who have previously undergone nondiagnostic blinded TBNA.

Adult↗
PubMed2000

Safety of bedside percutaneous dilatational tracheostomy in obese patients in the ICU.

STUDY OBJECTIVE: To examine the safety of bedside percutaneous dilatational tracheostomy in obese patients. DESIGN: Case series of consecutive obese patients (body mass index > or = 27 kg/m(2)) with acute respiratory failure in a medical, cardiac, or surgical ICU unit who required tracheostomy for failure to wean and continued mechanical ventilatory support. RESULTS: Thirteen obese patients were identified and consented to the procedure. Bedside percutaneous dilatational tracheostomy was successfully performed in the ICU for all 13 patients. Procedural complications were limited to paratracheal tracheostomy tube placement in one patient, with immediate identification and appropriate correction. Postprocedural complications were limited to a cuff leak in one patient. CONCLUSION: Bedside percutaneous tracheostomy can be safely performed in obese patients.

Acute Disease↗
PubMed1999

The cytochrome b5 tail anchors and stabilizes subdomains of human DNA topoisomerase II alpha in the cytoplasm of retrovirally infected mammalian cells.

DNA topoisomerase II (topo II) is the target of many anticancer drugs and is often altered in drug-resistant cell lines. In some tumor cell lines truncated isoforms of topo IIalpha are localized to the cytoplasm. To study the localization and function of individual enzyme domains, we have epitope-tagged several fragments of human topo IIalpha and expressed them by retroviral infection of rodent and human cells. We find that fusion of the topo II fragments to the hydrophobic tail of human liver cytochrome b5 anchors the fusion protein to the outer face of cytoplasmic membranes, as determined by colocalization with calnexin and selective detergent permeabilization. Moreover, whereas the minimal ATPase domain (aa 1-266) is weakly and diffusely expressed, addition of the cytb5 anchor (1-266-b5) increases its steady-state level 16-fold with no apparent toxicity. Similar results are obtained with the complete ATPase domain (aa 1-426). A C-terminal domain (aa 1030-1504) of human topo IIalpha containing an intact dimerization motif is stably expressed and accumulates in the nucleus. Fusion to the cytb5 anchor counteracts the nuclear localization signal and relocalizes the protein to cytoplasmic membranes. In conclusion, we describe a technique that stabilizes and targets retrovirally expressed proteins such that they are exposed on the cytoplasmic surface of cellular membranes. This approach may be of general use for regulating the nuclear accumulation of drugs or proteins in living cells.

Animals↗
PubMed1999

[Temporal bone fracture after head trauma causing rhinoliquorrhea and meningitis].

We report our experience in managing a temporal bone fracture after head trauma that had no apparent clinical signs. Recurrent CSF rhinorrhea and meningitis lead to extensive diagnostic procedures. Operative exploration of the temporal bone demonstrated a fracture line along the horizontal part of the carotid artery. The location of the fracture did not cause such typical symptoms as hearing impairment, facial paralysis, vertigo or tinnitus. Only CSF liquorrhea through the Eustachian tube indicated a fracture at the lateral skull base.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1999

Mechanisms of dominance: coexistence of picocyanobacterial genotypes in a freshwater ecosystem

The autotrophic picoplankton of the pelagic zone of the mesotrophic Lake Constance is dominated by phycoerythrin-rich unicellular cyanobacteria phylogenetically related to the marine Synechococcus and Prochlorococcus cluster. In Lake Constance, the abundance of picocyanobacteria shows a recurrent pattern of seasonal variations. Evidence of diverse subpopulations was obtained by electron-microscopic examination of natural water samples and isolated strains that unveiled different surface structures of picocyanobacteria. Further evidence was obtained by DNA analysis of 26 clonal isolates representing 12 different genotypes. Variations in light and nutrient supply revealed distinct abilities of the genetically different strains to cope with these stress situations. Furthermore, cultured heterotrophic nanoflagellates exhibited differential feeding preferences for certain Synechococcus strains. The findings imply that growth and loss rates of the natural cyanobacterial community may be influenced by its genetic composition. Phylogenetic analyses of isolated strains indicated that the physiological diversification of pelagic Synechococcus spp. has occurred during a recent adaptive radiation. An example for genetic mechanisms underlying physiological diversification is indicated by mobile DNA elements found in a Synechocystis strain also isolated from the pelagic zone of Lake Constance. The observations suggest that dominance of Synechococcus spp. was achieved by evolutionary adaptation and coexistence of numerous genotypes generating a physiologically highly diversified population.

Journal Article↗
PubMed1999

Inhibition of gap junctional coupling in cochlear supporting cells by gentamicin.

Gap junctional coupling of cochlear supporting cells is thought to be responsible for spatial potassium buffering of the microenvironment of outer hair cells (OHC). OHC of the organ of Corti are considered as the target of aminoglycoside-induced ototoxicity. Due to the proposed functional relationship between OHC and cochlear supporting cells we investigated a possible involvement of the supporting Hensen cells in the ototoxic effect of the aminoglycoside gentamicin. Isolated Hensen cell pairs were superfused by gentamicin-containing bath solutions. Using the double whole-cell patch-clamp method gentamicin (10 microM) inhibited gap junctional conductance by about 90%, whereas the membrane potential of about -27 mV remained unchanged. Since the inhibitory effect was suppressed by the addition of catalase, the gentamicin mediated effect probably is due to production of free radicals. It is proposed that formation of free radicals in supporting cells inhibits gap junctional coupling whereby the spatial potassium buffer mechanism and, thus, the fine tuning of the cochlear OHC is impaired.

Animals↗
PubMed1999

Ketorolac versus acetaminophen for treatment of acute fever in the emergency department.

BACKGROUND: The purpose of this preliminary study was to compare acetaminophen to ketorolac for treating patients with fever in the emergency department (ED). METHODS: In this prospective, randomized, double-blind pilot study, patients were enrolled as a convenience sample during a 6-month study period. All subjects 18 years or older with a temperature of 100.4 degrees F or higher were eligible. Investigators gave patients 10 mg of oral ketorolac or 750 mg of oral acetaminophen. The temperature and pulse were rechecked at 30, 60, and 90 minutes. Patients recorded discomfort on a visual analog scale (VAS) at 30, 60, and 90 minutes. RESULTS: A total of 17 patients were enrolled. A t test showed no difference in temperatures, and the Mann-Whitney nonparametric test showed no difference in VAS scores. CONCLUSION: In this preliminary study comparing ketorolac with acetaminophen for febrile illness in the ED, we found no difference in efficacy between the two medications.

Acetaminophen↗
PubMed1998

Lung abcess complicating Legionella micdadei pneumonia in an adult liver transplant recipient: case report and review.

Legionella micdadei (Pittsburgh pneumonia agent) is the second most common cause of Legionella pneumonia, and occurs predominantly in immunocompromised hosts. L micdadei is the cause of nosocomial pneumonia in renal transplant recipients, but has not been described in other adult solid organ transplant recipients. This report describes the first case of L micdadei pneumonia in an adult liver transplant recipient on immunosuppressive therapy. Importantly, this case highlights the difficulties in establishing the diagnosis, as the Legionella urinary antigen is negative, and special culture conditions are required. Furthermore, this case illustrates several atypical clinical features of L micdadei pneumonia in a transplant recipient, including a community acquired mode of transmission, occurrence several years after organ transplantation, and lung abcess formation. The patient was successfully treated with limited surgical resection and quinolone antimicrobial monotherapy.

Adult↗
PubMed1998

Colposcopy in evaluation of the adult sexual assault victim.

The purpose of this study was to determine if the colposcope improves detection of genital trauma in adult women who are victims of sexual assault compared with gross visual examination alone. A prospective, 1-month pilot study was conducted of 17 women patients who presented consecutively to Charity Hospital New Orleans during April 1994 requesting sexual assault examinations. Use of the colposcope allowed documentation of trauma in 9 of the 17 sexual assault victims (53%), compared with 1 of 17 (6%) by gross visualization alone (statistically significant: chi2 = 0.64, P = .0114). The colposcope improved detection of genital trauma in adult female sexual assault victims as compared with gross visual examination alone at a statistically significant level.

Adolescent↗
PubMed1998

Cochlear implantation in patients with chronic otitis: indications for subtotal petrosectomy and obliteration of the middle ear.

Normally, active chronic suppurative otitis media is regarded as a contraindication for cochlear implantation. In case of a radical cavity after surgical treatment for cholesteatoma, the electrode covered by the epithelial lining of the mastoid will likely become exposed or extruded. Under these circumstances we suggest the subtotal petrosectomy, obliteration of the middle ear cleft with abdominal fat, and the blindsac closure of the external ear canal before cochlear implantation.Fourteen patients with chronic otitis media were successfully implanted with an intracochlear multichannel cochlear implant. After an average follow-up of 28 months a temporary facial palsy in one patient and an insufficient closure of a retroauricular fistula over the mastoid cavity in two cases were observed as postoperative complications. One patient with a tumefactive inflammatory pseudotumor developed a massive inflammation in the implanted ear 2 months after surgery which could not be controlled by conservative treatment. The implant had to be removed and after administration of cyclophosphamide she could be successfully reimplanted 7 months later.Implantation of a foreign body in a potentially infected space which communicates with the endocranium means a surgical challenge which can be managed by obliteration of the middle ear. In case of massive inflammation we prefer a two-stage procedure.

Journal Article↗