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Biomedical subjects

S Schmid

Publications and source records attributed to S Schmid.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Significance of human papillomaviruses (HPV) in sinonasal papillomas].

The present study comprises 43 patients with sinonasal papillomas operated on between 1990 and 1997 at the ENT Department, University Hospital of Zurich. Histology showed 5 cases of exophytic papilloma (EP) (12%), 34 cases of inverted papilloma (IP) (79%) including 4 cases of associated carcinoma (9%), and 4 cases of columnar cell papilloma (CCP) (9%). Recurrence developed in 6 of 41 patients (2 EP, 4 IP) (15%). HPV was detected in 4 of 37 specimens (11%) both by in situ hybridization (ISH) and polymerase chain reaction (PCR). HPV-11 was found in 3 lesions (2 EP, 1 IP), whereas HPV-6b was detected only in one lesion (1 EP). Altogether 3 of 5 EP (60%), one of 29 IP (3%) and one of 6 recurrent papillomas (1 EP) (17%) tested positive for HPV. Our findings suggest a possible role for HPV in the pathogenesis of exophytic papilloma. As no correlation was found with associated malignancy and recurrence of disease, screening for HPV seems not to be useful as a prognostic parameter.

Cell Transformation, Neoplastic↗
PubMed2000

Technical tips and pitfalls in OPCAB surgery: the buffalo experience.

The Center for Minimally Invasive and Robotic Heart Surgery has performed more than 1,500 off-pump coronary artery bypass (OPCAB) procedures since 1995. The operation has changed significantly based on experience and development of new tools. These improvements have made the operations safer and applicable to more patients. No patients are presently scheduled for on-pump bypass surgery in our center. The purpose of this paper is to describe some of the problems and pitfalls we have experienced and how to avoid them.

Coronary Artery Bypass, Off-Pump↗
PubMed2000

[Indications and effects of the SMAS in parotid surgery].

The superficial musculoaponeurotic system (SMAS) is of increasing interest in parotid surgery as a means of reducing the incidence of postoperative gustatory sweating (Frey's syndrome) and improving cosmetic results. Between 1996 and 1998 the SMAS was dissected as a separate plane in 25 patients undergoing parotid surgery for a benign tumour or recurrent infection. After a minimal follow-up of 12 months, all patients were investigated for gustatory sweating and cosmetic appearance. All underwent the starch minor test to document the extent and intensity of postoperative sweating. In a previous publication we found a 43% incidence of Frey's syndrome after parotid surgery without SMAS dissection and starch minor tests were positive in all 23 patients. However, analysis of the current results in patients with SMAS dissection revealed an incidence of Frey's syndrome of only 20%, the results of starch minor tests being positive in 76% with a statistically highly significant (p = 0.006) decrease in extent and intensity. Cosmetic appearance was improved by reduction of the retromandibular depression. Dissection of the SMAS in parotid surgery is indicated in tumours not extending to the parotid capsula. It not only reduces the incidence of Frey's syndrome, but also improves the cosmetic result.

Digestive System Surgical Procedures↗
PubMed1999

Structures of Bi14WO24 and Bi14MoO24 from neutron powder diffraction data.

The (isomorphous) structures of Bi(14)WO(24), tetradecabismuth tungsten tetracosaoxide, and Bi(14)MoO(24), tetradecabismuth molybdenum tetracosaoxide, have been solved and refined using neutron powder diffraction data in the space group I4/m. The metal-atom array is fully ordered in terms of composition, and in terms of atomic positions deviates only slightly from a fluorite-type delta-Bi(2)O(3)-related parent structure. Three independent O-atom sites (accounting for 70 out of 78 O atoms in the unit cell) are also very close to fluorite-type parent positions. The remaining two O-atom sites, which coordinate W, exhibit partial occupancies and displacive disorder, neither of which could be better modelled by lowering of symmetry. The W site is coordinated by four O atoms in highly distorted tetrahedral coordination, the tetrahedron necessarily being orientationally disordered on that site. Nonetheless, the structure appears to be chemically reasonable.

Journal Article↗
PubMed1999

The crystal structure of Ca7Zr7Ta6O36 refined using synchrotron-radiation data.

Single-crystal X-ray diffraction data [synchrotron radiation; lambda = 1.2682 (4) Å] are used to solve and refine the crystal structure of heptacalcium hexatantalum heptazirconium hexatriacontaoxide, Ca(7)Zr(7)Ta(6)O(36). The structure adopts space group Fddd with cell dimensions a = 36.394 (1), b = 7.3674 (5), c = 31.006 (2) Å. The structure was solved by direct methods. Refinement using 1299 unique reflections leads to final values of R = 0.031 and wR = 0.034. The refined metal-atom ordering scheme is far from fully ordered and reminiscent of the A/B metal-atom ordering characteristic of the pyrochlore structure type. Bond-valence sums are calculated to confirm the plausibility of the crystal chemistry of Ca(7)Zr(7)Ta(6)O(36).

Journal Article↗
PubMed1999

Voltage-activated calcium currents in rat retinal ganglion cells in situ: changes during prenatal and postnatal development.

Voltage-activated calcium currents (ICa) are one way by which calcium influx into neurons is mediated. To investigate changes in kinetic properties of ICa during neuronal development and to correlate possible kinetic changes with specific differentiation processes, the ICa of retinal ganglion cells (RGCs) was recorded with the perforated patch-clamp technique in rat retinal slices and in whole mounts at different prenatal and postnatal stages. ICa density increased between embryonic day (E) 20 and the adult stage, paralleled by a shift in activation of the omega-conotoxin GVIA-sensitive ICa toward more negative membrane potentials. Furthermore, developmental alterations were observed in ICa inactivation rate during a 120 msec test pulse and in steady-state inactivation of ICa. The most striking feature in ICa kinetics was a transient slowing of calcium current deactivation, which peaked at postnatal day (P)3-5 and affected all ICa subtypes. Although the shift in activation and the decreased inactivation rate of ICa can be explained by differential regulation of distinct calcium channel subtypes, it is more likely that a more general alteration of the cells' functional state was the underlying factor in alterations in steady-state inactivation and current deactivation of ICa. Alterations in the omega-conotoxin GVIA-sensitive and the toxin-resistant currents temporarily coincide with dendritic differentiation, and it is tempting to speculate about their role in network formation in the inner retina. In contrast, alterations in steady-state inactivation and current deactivation may be involved in the regulation of RGC survival, because they occur during the period of programmed cell death in the ganglion cell layer. In conclusion, distinct time windows of alterations in calcium channel properties were found, and this study has provided a basis for performing functional assays to clarify in detail the developmental process to which these alterations are related.

Aging↗
PubMed1999

Solution and refinement of the crystal structure of Bi7Ta3O18.

The structure of heptabismuth tritantalum octadecaoxide, Bi(7)Ta(3)O(18), has been solved and refined using single-crystal X-ray diffraction data collected at a synchrotron source in conjunction with unit-cell and symmetry information derived from electron diffraction. The space-group symmetry is triclinic C1 but is very close to monoclinic C2/m. A twin component observed during data collection was successfully modelled in the refinement. The C2/m prototype fitted all the Rietveld-refinable features of a medium-resolution neutron powder diffraction pattern. The metal-atom array is approximately face-centred cubic (fluorite type), punctuated by regularly spaced displacement faults perpendicular to the [111](fluorite) direction every 2.5 fluorite unit cells. The metal-atom populations and O-atom positions are fully ordered. The Ta(5+) cations are octahedrally coordinated, with TaO(6) octahedra forming columns. The remaining O atoms occupy distorted fluorite positions. The Bi(3+) cations occupy octahedral, square pyramidal or trigonal prismatic sites within the O-atom array; strain in the latter coordination environment appears to be responsible for the lowering of symmetry from monoclinic to triclinic.

Journal Article↗
PubMed1999

[Primary small cell carcinomas and metastatic disease in the head and neck].

Extrapulmonary small cell carcinomas are recognized as a clinicopathologic entity distinct from small cell lung cancer. Such carcinomas as primary tumors have been described in several locations in the head and neck although most cases of metastatic tumor in the neck originate from a pulmonary primary. In this report we present a small cell carcinoma of the larynx, metastasis in the parotid gland as the first manifestation of a small cell lung cancer and a small cell carcinoma of the Merkel cell type in a parotid lymph node. Our review of the current literature shows that most small cell carcinomas in the head and neck are extrapulmonary primary tumors. Since histological criteria are the same, a pulmonary neoplasm has to be excluded in every case. The differentiation between a primary head and neck tumor and metastatic disease as well as the location and staging are essential criteria for therapy and prognosis.

Carcinoma, Merkel Cell↗
PubMed1999

Maturation of intrinsic membrane properties in rat retinal ganglion cells.

In view of the prominent role of voltage-activated conductances in both neuronal differentiation and signal transmission, the present study describes developmental alterations of ion channel properties during the functional maturation of rat RGCs, i.e., between embryonic day 15 when RGCs start to differentiate (E15) and postnatal day 35 (P35) when the retina is fully developed and the animals had already visual input for about 2 weeks. While the sodium system seems to reach maturity already at the end of the second postnatal week, significant alterations in the potassium system were found only from postnatal day 10 on. The functional implications of these alterations are discussed.

Action Potentials↗
PubMed1999

An update on the surgical treatment of temporal bone paraganglioma.

In 1982, Fisch described his results for the surgical treatment of 74 paragangliomas of the temporal bone, 5 years after his description of the infratemporal fossa approaches (types A and B). This study reviews the subsequent experience of the Department of Otolaryngology-Head and Neck Surgery of the University of Zürich with more than 136 surgically treated cases of paraganglioma of the temporal bone and discusses our current therapy 20 years after the initial description. One hundred nineteen (90%) of the patients had advanced tumors (Fisch class C or C+D), and 81 (68%) had intracranial extension. Total tumor excision was possible in 109 (82%) patients. Subtotal excision was performed in 22 (17%) patients, 21 of whom had intradural tumor invasion. In these cases, the resection was limited not by actual tumor size but by the degree of intracranial intradural tumor extension. Partial tumor excision was undertaken in only 1 patient with a C4De2Di2 tumor. The success rate in preservation of function of the lower cranial nerves was encouraging. Of the 69 patients whose facial nerve status was followed post-operatively, 81% maintained Fisch grade 76 to 100% (House-Brackman grades I and II). Analysis of follow-up data ranging from 2 to 11 years demonstrated 98% disease-free survival when total tumor extirpation was possible. In the patients who underwent subtotal or partial surgical resection there has been no subsequent tumor growth detected by either clinical or neuroradiological evaluation. We have confirmed after more than 20 years of experience that the infratemporal fossa approaches are a safe, highly effective means of surgical management of paragangliomas of the temporal bone, allowing eradication or arrest of disease with minimal morbidity. Limited intradural surgical resection in cases of very extensive tumors can greatly benefit patients for whom complete excision is not an option.

Journal Article↗
PubMed1999

High prevalence and incidence of sexually transmitted diseases in urban adolescent females despite moderate risk behaviors.

To better understand the prevalence, incidence, and risk factors for sexually transmitted diseases (STDs) among female adolescents, a prospective 6-month cohort study was conducted at four teen clinics in a southeastern city. At enrollment, 260 (40%) of 650 sexually active females ages 14-19 years had an STD: chlamydia, 27%; herpes simplex virus type 2 (HSV-2), 14%; gonorrhea, 6%; trichomoniasis, 3%; and hepatitis B, 2%. At follow-up, 112 (23%) of 501 participants had an incident infection: chlamydia, 18%; HSV-2, 4%; gonorrhea, 4%; and trichomoniasis, 3%. At either enrollment or follow-up, 53% had >/=1 STD; of those with 1 lifetime partner, 30% had an STD. Having a new partner (odds ratio [OR], 2.2; 95% confidence interval [CI], 1. 1-4.2) or friends who sell cocaine (OR, 1.6; CI, 1.0-2.6) was independently associated with incident infection. STD incidence and prevalence were extremely high in this population, even in teenagers with only 1 lifetime partner. Individual risk behaviors appeared less important for STD risk than population factors.

Adolescent↗
PubMed1999

Microsatellite analysis in serous tumors of the ovary.

Thirty-four serous ovarian neoplasms were analyzed for microsatellite instability (MIN) and loss of heterozygosity (LOH) at 20 chromosomal loci of eight different chromosomes, including the map positions of the six known mismatch repair genes. Twelve of the 20 (60%) serous ovarian tumors of low malignant potential (LMP) and 13 of 15 (87%) samples of serous ovarian carcinomas, taken from 14 patients, showed LOH at one or more of the analyzed microsatellite loci. In serous carcinomas, LOH of the dinucleotide repeat D7S521 was most frequent. Six of 20 (30%) LMP tumors were also affected by MIN at more than one locus, whereas in the carcinomas MIN was found only sporadically (p < 0.025). No correlation between increased occurrence of MIN and LOH at the chromosomal loci of the known mismatch repair genes were discovered for these LMP tumors. Although our observation regarding LOH frequency in serous LMP tumors and serous carcinomas is compatible with the hypothesis that serous LMP tumors might represent precursor lesions of invasive carcinomas, the results concerning the occurrence of MIN suggest that the mechanisms of tumorigenesis of some tumors of LMP are distinct from those in invasive serous carcinomas.

Aged↗
PubMed1999

A prospective randomized double-blind trial of fibrin glue for pain and bleeding after tonsillectomy.

OBJECTIVES: The notable morbidity of tonsillectomy includes considerable postoperative pain and a rate of postoperative bleeding that have remained largely uninfluenced by modern surgical techniques or medication. Fibrin glue is known to have a hemostatic effect in some settings, and there is research suggesting it may also reduce postoperative pain. The objectives of this study were to evaluate the effect of fibrin glue on pain and bleeding after tonsillectomy. STUDY DESIGN: A prospective randomized double-blind study was performed on 50 consecutive adult patients undergoing tonsillectomy for chronic tonsillitis. METHODS: After removal of both tonsils the tonsillar fossa randomly assigned to the treatment protocol was coated with fibrin glue. The other side was left unaltered. The patient was then monitored for postoperative bleeding and wound healing, and a patient-based pain assessment instrument was used to evaluate symptoms every 8 hours for 10 days after surgery. RESULTS: Detailed evaluation of the pain scores allowed the authors to create a pain profile for what the typical patient experiences over the first 10 postoperative days, as well as during the course of a single day. The pain remains relatively constant for the first 7 days and begins to decrease only on the eighth postoperative day. During a single day there is increased pain in the morning compared with noon and evening. However, no statistically significant difference was detected in postoperative pain, bleeding, or healing between the wounds treated with fibrin glue and controls. CONCLUSIONS: The patient-based pain evaluation data should aid the physician in preoperative outcome counselling and targeted prescription of pain medication. However, contrary to previous indications, the authors cannot substantiate a significant beneficial effect of fibrin glue in postoperative pain control. Furthermore, we did not find its action as a hemostatic agent clinically applicable in this setting, and thus find no indication for the routine use of fibrin glue in tonsillectomy.

Adolescent↗
PubMed1999

Interplays between mouse mammary tumor virus and the cellular and humoral immune response.

Mouse mammary tumor virus has developed strategies to exploit the immune response. It requires vigorous immune stimulation to achieve efficient infection. The infected antigen-presenting cells present a viral superantigen on the cell surface which stimulates strong CD4-mediated T-cell help but CD8 T-cell responses are undetectable. Despite the high frequency of superantigen-reactive T cells, the superantigen-induced immune response is comparable to classical antigen responses in terms of T-cell priming, T-cell-B-cell collaboration as well as follicular and extra-follicular B-cell differentiation. Induction of systemic anergy is observed, similar to classical antigen responses where antigen is administered systemically but does not influence the role of the superantigen-reactive T cells in the maintenance of the chronic germinal center reaction. So far we have been unable to detect a cytotoxic T-cell response to mouse mammary tumor virus peptide antigens or to the superantigen. This might yet represent another step in the viral infection strategy.

Amino Acid Sequence↗
PubMed1999

Target joining of duplicated insertion sequence IS21 is assisted by IstB protein in vitro.

Tandemly repeated insertion sequence IS21, located on a suicide plasmid, promoted replicon fusion with bacteriophage lambda in vitro in the presence of ATP. This reaction was catalyzed in a cell extract containing the 45-kDa IstA protein (cointegrase) and the 30-kDa IstB helper protein of IS21 after both proteins had been overproduced in Escherichia coli. Without IstB, replicon fusion was inefficient and did not produce the 4-bp target duplications typical of IS21.

Artificial Gene Fusion↗
PubMed1999

Percutaneous tracheostomy: a comprehensive evaluation.

Percutaneous tracheostomy (PT) is an ancient procedure that has recently attracted increasing interest. While there are numerous publications in the literature, there remains confusion due to the large variety of techniques and instruments with which it has been performed and the wide disparity in clinical outcome. This study evaluates the international literature on over 1,500 cases, classifies the techniques that have been used, analyzes the safety of each method, and reports a prospective outcome and cost analysis of 130 cases undergoing what we determined to be the safest method. We found that PT performed with the correct instruments and technique under bronchoscopic surveillance has a lower incidence of complications than open tracheostomy (OT). Cost estimation demonstrated that PT may be significantly more expensive than bedside OT. While we recommend PT as a relatively safe and expedient method of tracheostomy for selected intubated patients in an intensive care unit, it does not offer an advantage for patients who must be taken to the operating room, and should not deprive house officers of necessary experience in OT in this setting.

Adolescent↗