Biomedical subjects
Publications and source records attributed to S Schmid.
The footplate only situation remains the greatest challenge of ossicular reconstruction. This article discusses the long term results obtained with a new type of columella, the Spandrel, which combines the rigidity necessary for sound transmission with the flexibility required to comply with the dynamic movements of the neotympanum.
Twenty years experience of lateral parotidectomy as suspical treatment for pleomorphic adenoma are reviewed. All cases were managed at the ORL Clinic of the University of Zürich. 167 patients were followed for the frequency of possible recurrent tumors. Three patients (3/123) operated primarily developed a recurrences. Recurrences appeared after an average of 10 years, ranging from 1-30 years. The follow-up time varied from 1 to 21 years (average, 8 years). 39% (13 of 33) of the patients, who were re-operated for a recurrent tumor, developed another recurrence. The second recurrence appeared after an average of 10 years, ranging from 1-22 years. A persistent partial paresis of the facial nerve was found in 1% of the patients operated primarily and in 9% of the patients operated more than once. No paralysis was seen. We now choose "en-bloc" resections of pleomorphic adenomas without intra-operative opening of the tumor capsule as the treatment of choice. This treatment was possible in 83% of all cases, using a lateral parotidectomy. If tumor extends into the medial parotid lobe, total parotidectomy is required.
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The effect of corticotropin releasing factor (CRF) on atrial natriuretic peptide (ANP) release and its possible modulation by indomethacin, norepinephrine, propranolol and nitro-L-arginine (an inhibitor of the endothelium-derived relaxing factor (EDRF) release) was investigated, using an isolated perfused rat heart preparation. Bolus injection of 5 micrograms CRF, dissolved in 100 microliters perfusion buffer, provoked a significant (p < 0.01 vs. control) short-time increase of ANP release. Indomethacin (3 x 10(-5) mol/l) inhibited the CRF-stimulated increase of ANP release and decreased the basal ANP secretion (p < 0.01 vs. CRF group). Norepinephrine (10(-9) mol/l) slightly, but not significantly, decreased the CRF-stimulated ANP release and did not change the basal ANP output. Propranolol (3 x 10(-6) mol/l) did not alter ANP release. Nitro-L-arginine (3 x 10(-5) mol/l) increased the basal ANP release (p < 0.01 vs. CRF group) and prolonged the CRF-induced rise of the ANP secretion. The present data suggest that prostaglandins are important mediators of basal and CRF-stimulated ANP release and that EDRF might be a physiological inhibitor of ANP release.
The leading symptom of proliferative myositis is a rapidly growing hard tumor in the muscle. The disease is rare and therefore widely unknown. We observed a case of proliferative myositis in a 54-year-old female. We initially interpreted the hard tumor in the left musculus sternocleidomastoideus and its rapid growth as a malignant disease. The histological findings finally led to the correct diagnosis. In the light of the literature of 78 reported cases, a presumptive diagnosis can already be suspected from the clinical examination. The addition of CT scan and fine needle aspiration is highly diagnostic.
A total of 59 female infertile patients were investigated for the concentration of polychlorinated biphenyls (PCB) in their blood serum and follicular fluid. The average concentration of PCB in 66 related samples of follicular fluid and blood serum was 1.6 and 1.8 ng/ml, respectively. A splitting of the patients into two collectives, one with explained infertility, the other with unexplained infertility, showed no evidence of a higher PCB concentration in unexplained infertility patients. These results may exclude PCB as a primary reason for unexplained infertility.
The infratemporal fossa approach to the skull base is an established method of treating neoplasms of this region. The type C variation has proved an effective means of removing adenoid cystic carcinoma invading the infratemporal fossa and skull base from the nasopharynx. A classification of these tumors is proposed, the surgical technique is described, and the results are given in this article.
This report deals with the first 350 laparoscopic cholecystectomies performed at Creighton University, beginning in October 1989, by one of the authors (R.J.F., Jr.). An open technique was used for initial access to the abdominal cavity in 343 patients (98%). Patients included 274 females and 76 males, with an average age of 45.5 years. Weight ranged from 72 to 316 pounds (32-142.2 kg). The laparoscopic procedure was successfully completed in 338 (96.6%). Operative cholangiography was performed in 113 (32.3%), and 52 (14.7%) had acute cholecystitis as determined by the final pathological report. Median operating time was 80 min. There was no operative mortality. Bile duct injury was not seen. Postoperative complications occurred in 21 patients (6%), only two of which were directly related to the open technique (cellulitis of the umbilical wound requiring antibiotics). A third patient (0.3% of 343 successful laparoscopies) required reoperation on postoperative day 4 for a small bowel perforation; the exact cause could not be determined, but conceivably it was related to the umbilical minilaparotomy. We conclude that the open technique is safe and effective method for initial peritoneal access prior to laparoscopic cholecystectomy.
A total of 73 postterm pregnancies (greater than or equal to 294 days gestational age) were studied retrospectively and showed the following results: the frequency of postterm pregnancies was 1.5%. Compared to a control group of normal pregnancies (262-293 days), there was no evidence of a higher risk for infants born after term. As far as the different routes of delivery are concerned, there was a slightly higher number of cesarean sections and a markedly higher number of surgical vaginal deliveries in postterm pregnancies.
The modern concept of an open cavity is to combine a safe with a dry, self cleansing ear. The prerequisites to achieve this goal are: the radical exenteration of the mastoid, antrum and epitympanum, the maximal reduction of the volume of the cavity by extensive lateral removal of bone and the adequate shaping of the cavity walls by obliteration of the bone pockets. To perform correctly a radical mastoido-epitympanectomy with tympanoplasty and partial obliteration is difficult and requires a perfect anatomical knowledge of the deepest regions of the temporal bone, particularly of the supralabyrinthine space. Using the technique exposed in this article, 75 out of 79 ears (95% of our revision cases) achieved a dry and self cleansing cavity at three years follow-up.
We investigated the feasibility of micro-encapsulation technology for the evaluation of anti-human immunodeficiency virus (HIV) drugs in vivo. The ability to place human cells in microcapsules with semipermeable membranes for implantation into test animals led to the development of this assay. The anti-HIV activity assay involves microencapsulating human T-lymphoblastoid cells sensitive to the cytopathic effects of HIV; the encapsulated cells are then implanted into athymic nude mice and recovered after drug treatment in vivo. A positive antiviral effect of the test substance is indicated by growth or survival of the virus-infected cells in the microcapsules. Several HIV-sensitive cell lines of T-lymphocyte, monocyte, and nonlymphocyte origin were examined for growth in microcapsules in vitro and in vivo. Light and electron microscopic analysis of the capsules and the human cells contained therein revealed the invasion of mouse immune cells and other adverse effects that could not be overcome by any of numerous technical modifications attempted. We conclude that cellular microencapsulation technology is not feasible for in vivo drug-testing protocols because of immunogenic reactions.
Pulmonary hypertension without any cardiovascular malformation was diagnosed by heart catheterization in a 4 year old girl with trisomy 21. A suspected obstructive sleep apnea syndrome was confirmed by polysomnography which revealed numerous obstructive apneas and hypopneas (apnea-index 23/h) with marked oxygen desaturation and a disturbed sleep pattern. Three months after adenotonsillectomy the mother reported her daughter having a quiet sleep without snoring. Polysomnography did not show any apnea nor any oxygen desaturation below 90%. A decrease of the pulmonary artery pressure was documented. Facial dysmorphias and muscle hypotonia predispose patients with trisomy 21 to obstructive sleep apnea, especially if hypertrophy of tonsills and adenoids coexist. Frequent arousals and hypoxia during sleep can result in failure to thrive and pulmonary hypertension. These consequences can be prevented by early diagnosis and treatment.
An isotachophoretic method for the determination of free [Al(H2O)6]3+ ions in different aluminium salt solutions was developed. The electrolyte system consists of 0.01 M sodium acetate (leading system) and 0.01 M tris(hydroxymethyl)amino-methane (terminating system). Separation was effected with a precapillary tube (diameter 0.05 cm) followed by a main capillary tube of length 20 cm and of smaller cross-section. The detection limit for [Al(H2O)6]3+ ions was 0.05 mg/l. The method was applied to the determination of free Al3+ ions ([Al(H2O)6]3+) in soil leachates and aqueous soil extracts.
Endosomes maintain a slightly acidic internal pH, which is directly responsible for their ability to ensure proper sorting of incoming receptors and ligands during endocytosis. At least two distinct subpopulations of endosomes can be distinguished, designated "early" and "late" on the basis of their kinetics of labeling with endocytic tracers. The subpopulations differ not only in their functions (rapid receptor recycling and transport to lysosomes, respectively) but also in their capacities for acidification in intact cells and in vitro. To investigate the possible basis for pH regulation in endosomes, we have studied the transport properties and ion permeabilities of early and late endosomes isolated from Chinese hamster ovary cells. Using endosomes selectively labeled with pH-sensitive endocytic tracers, we found that ATP-dependent acidification is electrogenic, being accompanied by the generation of an interior-positive membrane potential which opposes further acidification. While membrane potential and, consequently, acidification was controlled by the influx of permeant anions and efflux of protons and alkali cations, acidification was further modulated in Na+ and K+-containing buffers by the ouabain- and vanadate-sensitive Na+,K+-ATPase, which appears to be a functional component of the endosomal membrane. The data suggest that electrogenic Na+ transport due to Na+,K+-ATPase activity contributes to the interior-positive membrane potential, thereby reducing ATP-dependent H+ transport. Importantly, inhibition of acidification by Na+,K+-ATPase activity was found only in early endosomes, consistent with their limited acidification capacity relative to late endosomes and lysosomes.
During endocytosis in Chinese hamster ovary (CHO) cells, Semliki Forest virus (SFV) passes through two distinct subpopulations of endosomes before reaching lysosomes. One subpopulation, defined by cell fractionation using free flow electrophoresis as "early endosomes," constitutes the major site of membrane and receptor recycling; while "late endosomes," an electrophoretically distinct endosome subpopulation, are involved in the delivery of endosomal content to lysosomes. In this paper, the pH-sensitive conformational changes of the SFV E1 spike glycoprotein were used to study the acidification of these defined endosome subpopulations in intact wild-type and acidification-defective CHO cells. Different virus strains were used to measure the kinetics at which internalized SFV was delivered to endosomes of pH less than or equal to 6.2 (the pH at which wild-type E1 becomes resistant to trypsin digestion) vs. endosomes of pH less than or equal to 5.3 (the threshold pH for E1 of the SFV mutant fus-1). By correlating the kinetics of acquisition of E1 trypsin resistance with the transfer of SFV among distinct endosome subpopulations defined by cell fractionation, we found that after a brief residence in vesicles of relatively neutral pH, internalized virus encountered pH less than or equal to 6.2 in early endosomes with a t1/2 of 5 min. Although a fraction of the virus reached a pH of less than or equal to 5.3 in early endosomes, most fus-1 SFV did not exhibit the acid-induced conformational change until arrival in late endosomes (t1/2 = 8-10 min). Thus, acidification of both endosome subpopulations was heterogeneous. However, passage of SFV through a less acidic early endosome subpopulation always preceded arrival in the more acidic late endosome subpopulation. In mutant CHO cells with temperature-sensitive defects in endosome acidification in vitro, acidification of both early and late endosomes was found to be impaired at the restrictive temperature (41 degrees C). The acidification defect was also found to be partially penetrant at the permissive temperature, resulting in the inability of any early endosomes in these cells to attain pH less than or equal to 5.3. In vitro studies of endosomes isolated from mutant cells suggested that the acidification defect is most likely in the proton pump itself. In one mutant, this defect resulted in increased sensitivity of the electrogenic H+ pump to fluctuations in the endosomal membrane potential.
Thirty-three synthetic middle ear prostheses removed after two to 99 months of implantation were examined histologically. All prostheses were infiltrated by fibroblasts, capillaries, collagen fibrils, and multinucleate foreign body giant cells. Although some of the giant cells contained tiny particles of the prosthetic material, there was no evidence of erosion or engulfment of larger particles of the prosthesis or structural dissolution of the prosthesis. New histologic findings were aseptic necrosis and focal calcification in the interior of some of the prostheses.
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