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Biomedical subjects

M Portmann

Publications and source records attributed to M Portmann.

17 recordsLinked to original sources
PubMed1992

Laser micromanipulation in the mouse embryo: a novel approach to zona drilling.

OBJECTIVE: To introduce the use of excimer lasers for penetration of the zona pellucida for micromanipulation purposes. DESIGN: Cryopreserved two-cell mouse embryos were thawed and exposed to the 248-nm line of a krypton fluoride excimer laser (Lambda Physik EMG 202, Goettingen, Germany) creating a 2 to 4-micron opening in the zona pellucida. SETTING: The Laser Ablation Laboratory at DuPont and the in Vitro Fertilization Laboratory at The Medical Center. INTERVENTIONS: The embryos were exposed in either phosphate-buffered solution (PBS) or modified human tubal fluid (HTF) with the laser power varying from 1 to 2 J/cm2 and cultured in Ham's F-10 medium (GIBCO, Grand Island, NY) with 0.4% bovine serum albumin. MAIN OUTCOME MEASURES: The outcome of each experiment was measured by blastocyst formation of laser-exposed embryos as compared with a set of unexposed control embryos handled in a similar fashion. RESULTS: Successful laser penetration of the zona pellucida was achieved using the 248-nm line of a krypton fluoride excimer laser. A higher blastocyst formation was found for embryos exposed in PBS. The higher optical absorption of the modified HTF partially inhibited embryo development. The blastocyst statistics increased 2.5-fold times by reducing the exposure of the embryos to ablation by-products. CONCLUSIONS: The use of a krypton fluoride excimer laser was introduced as a new method to open the zona pellucida of two-cell mouse embryos without interrupting blastocyst formation.

Animals↗
PubMed1992

Problems in alloplastic middle ear reconstruction.

Alloplastic materials have been used in middle ear reconstruction since 1952. Biologically, biomaterials and specifically ceramics can be defined as being bioinert, bioactive or biodegradable; these terms being descriptive of the biochemical response provoked by the material in the host tissue. Various ceramics, carbons and polymers and their reactions have been studied by the author and his colleagues over the past 5 years utilising animal implantation and fibroblast culture studies aligned with experience from clinical usage. The qualities of the ideal alloplastic implant namely: biocompatibility, stabilisation and incorporation, the consistency of the implant and bioactive bonding and the biofunctionality or mechanics, are applied to the materials currently available. No single alloplastic material fulfills all criteria, the problems encountered in relation to the biomaterials are reported. A better understanding of the microstresses, fatigue and microfractures is necessary, before the ideal alloplastic biomaterial becomes available.

Animals↗
PubMed1992

[Congenital cholesteatoma of the middle ear and mastoid. Apropos of 5 cases].

Five cases of congenital cholesteatoma of the middle ear and mastoid as defined by Derlacki's criteria were encountered over a 14 month period. They make up 5% of all cases of cholesteatoma managed over the same period of time. Three were young children and all presented with unilateral hearing loss. One had associated multiple congenital abnormalities of the external and middle ear. Only in one patient was the diagnosis made on initial otoscopic examination and the remainder diagnosed on CTscan, myringotomy and tympanotomy. All were operated on; three by the intact canal wall technique, one by the canal down technique with mastoid cavity obliteration and one by atticotomy with lateral attic wall reconstruction. One patient required a second stage operation for excision of an extension of disease deep to the superior semicircular canal via the middle cranial fossa approach in order to preserve cochlear function. These five cases illustrate the diagnostic pitfalls of this condition in which silent danger lurks behind an intact tympanic membrane.

Adult↗
PubMed1992

[Apropos of the infratemporal pre-auricular approach (its value in the approach to the midline skull base].

The role of the infratemporal pre-auricular pathway to the median base of the skull resides in the fact that it enables very wide access to this region while sparing the facial and auditory nerves. Among the operations performed on the approaches of the base of the skull by their teams, the authors chose a particularly typical observation dealing with the indication of this pathway: a 34-year old male with a giant cholesteatoma of the tip of the petrous bone totally surrounding the internal carotid artery along its entire (intrapetrous) length, from the cervical region to the cavernous sinus, having invaded the clivus and pushed back the brainstem. This lesion is located on the side of the only healthy ear. The patient is completely deaf in the ear on the other side. The operation enabled its complete exeresis while respecting the facial, auditive and vestibular functions.

Adult↗
PubMed1975

[Acoustic neuroma. Apropos of a series of 40 cases].

The authors present statistics of 40 acoustic neuromas operated upon by micro-surgical technique in co-operation with oto-neuro-surgery. As regards clinical picture, all persons presenting with unilateral progressive sensoryneural deafness should be subjected to cochlear vestibular and radiologic examination. They advocated essentially two routes:--translabyrinthine approach for the tumours within the internal auditory meatus, --posterior fossa approach for the other tumours. They reported their results and analysed the major advantages of the microsurgical technique which diminish considerably the risk of this surgery, so that the functional result should be of first importance.

Adult↗
PubMedDate not supplied

Temporary tinnitus suppression in man through electrical stimulation of the cochlea.

While investigating the possibilities of electrically induced hearing in cases of profound deafness, we observed that very often an appropriate stimulation of the cochlea could result in tinnitus cancellation. We present here a progress report on that phenomenon, including 15 subjects. Such a cancellation was restricted to tinnitus subjectively localized in the ear under test, we observed no effect on noises localized in the other ear, or centrally. This suppression occurred so long as the cochlea was stimulated and stopped when the stimulation ceased. This phenomenon was very reproducible and did not seem to affect simultaneous normal acoustic hearing. It is hypothesized that this phenomenon acts through an inhibition of abnormal activity of sensorineural elements of the electrically stimulated cochlea.

Cochlea↗