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Biomedical subjects

H Martin

Publications and source records attributed to H Martin.

At least 199 records · Page 11Linked to original sources
PubMed1991

[A measuring procedure for experimental determination of tensile strength of catheters and flexible probes].

In order to obtain a more objective description of the properties usually subsumed under such terms as the "handling" of catheters, it is necessary to measure the significant parameter bending stiffness. A contact-free method of recording the oscillations of rod-shaped elements is presented. The stiffness EI can be calculated from the measured characteristic frequency. The logarithmic decrement can be derived from the damped natural oscillation and the damping properties of the catheter thus characterised. In addition, a consideration of imposed oscillations can be employed to calculate resonance frequency. A computer-driven measuring set-up employing a CCD line camera for the non-contact recording of oscillations of rodshaped elements, together with the software required is presented. The measuring principle and possible errors are discussed and a measurement described by way of an example.

Biomechanical Phenomena↗
PubMed1991

[Facial motricity of trigeminal origin. Apropos of a typical case and review of the literature].

The authors report the case of a patient who underwent the neurosurgical exeresis of an acoustic neuroma 14 years ago, and subsequently presented with a total facial palsy in spite of a spinofacial anastomosis. This patient had to be reoperated because of tumoral recurrence compressing the trigeminal nerve (V). This operation, through atranslabyrinthic that also emptied the entire internal auditory canal of its neural elements, allowed removing the neuroma. Once the facial nerve had been resected, the patient recovered some facial motricity and his masticatory function improved on the day following the operation. Since the contralateral facial nerve was not involved and the spinofacial anastomosis was absolutely not functional, only motor reinnervation from the trigeminal nerve was possible. The anatomy of the facial and trigeminal nerves in summarized, and their central connexions and peripheral anastomoses are studied. Out of the 27 cases of spontaneous motor reinnervation following the resection of the facial nerve described in the literature, only one similar case of recovery of motricity after a major nerve resection in the cerebellopontine angle is reported. Such a phenomenon can be explained only by the transformation of some sensory fibers of the 5th cranial nerve into motor fibers, which are activated by the resection of the 7th nerve and receive their nervous influx from the motor nucleus of the 5th or 7th nerve through protuberantial communications.

Facial Nerve↗
PubMed1991

[Measurement of the number, size and location of AgNORs in histologic sections of astrocytomas and bladder carcinoma].

Nucleolus organizer regions (NORs) are associated with proliferative activity of tumors. An image analysis method is presented in this paper by which it is possible to analyze NOR location within the nucleus and relative to each other. Several features which characterized locations were measured in 20 urinary bladder carcinomas, eight astrocytomas, and two glioblastomas. Correlations were found to exist between those features, on the one hand, and tumor malignancy, on the other. They were particularly close in astrocytoma. Mean distance among NORs and closeness to the nuclear membrane were found to increase, as well, along with aggravating malignancy. As to the urinary bladder carcinomas examined, an unambiguous difference was found to exist between G 1 and G 1-2 carcinomas.

Astrocytoma↗
PubMed1991

[AgNORs in cells of urothelial carcinoma of the bladder. A quantitative study using automatic microscopic image analysis].

Biopsies taken from 52 cases of urinary bladder carcinoma together with samples collected from 6 controls were stained to visualize AgNORs, using a technique modified by the authors of this paper after its first introduction to histological practice by Ploton et al. (1986) as well as by Crocker and Nar (1987). AgNORs were quantitatively analyzed by means of an image processing system and a programme written by the authors' team for this particular purpose. The configuration was such that information was provided on the number and size of AgNORs. AgNORs were found to go up numerically along with aggravating malignancy, means values being 1.7/cell nucleus in Grade 1 urothelial carcinomas (controls being 1.6), 2.6 in Grade 2, and 3.3 in Grade 3. Mean AgNOR sum areas in the three above tumor groups were 3.4 microns 2, 7.4 microns 2, and 12.8 microns 2 (controls being 2.6 microns 2). Analysis of AgNORs, consequently, should provide prognostically relevant information helpful in more effective grading of urinary bladder carcinoma.

Carcinoma, Transitional Cell↗
PubMed1991

Cleanliness, disinfection, and sterilization of the root canal.

Disinfection is a key aspect in the preparation of root canals prior to obturation. Irrigation and intracanal medicaments are the chemical means of debridement. The bacterial role is significant, and intracanal medicaments must be cidal in their effect on bacteria and the dentinal tubules. Topical application of medicaments seem to be as effective or more effective than antibiotic applications. Glutaraldehyde and calcium hydroxide are two of the more recently studied medicaments. Calcium hydroxide shows promise as an effective microbicide. The importance of removal of bacteria and necrotic debris from the canal by chemomechanical means--mechanical preparation, cidal irrigation, antimicrobial medicaments--will enhance the successful outcome of endodontic therapy.

Calcium Hydroxide↗
PubMed1991

[Menière's disease. A psychosomatic disease?].

Although psychosomatic aspects of Meniere's disease have already been pointed out by some authors, few papers have been publisched on this question. 48 patients suffering from Meniere's disease underwent in addition of a complete audiological examination a psychosomatic study using two psychometric auto evaluation tests. It appears that patients suffering from Meniere's disease have a significantly different psychopathologic personality than normals (anxiety, depressive tendency, phobia). Besides, an obvious correlation is found between deafness, vertigo's recurrences and psychopathological disorders. These findings must be taken into consideration to treat patients suffering from Meniere'es disease.

Ambulatory Care↗
PubMed1991

[Stapes decompression].

Footplate decompression, which has been described in Lyon in 1965, can be easily performed under local anesthesia. The surgical procedure consists of a 8/10 mm diameter stapedotomy followed by an obturation with spongel, gelfoam or a piece of thin fascia. The operation is not a labyrinthectomy or a sacculotomy but aims to decompress endolymphatic hydrops in Ménière's disease. It must be realised only in case of typical unilateral Ménière's disease with disabling vertigo and very poor residual hearing. More than two hundred cases have been operated on. Vertigo has been relieved in 90% of the operated cases, tinnitus less severe in 50% of cases and hearing sometimes worse but often unchanged. In patients suffering from a unilateral Ménière's disease with disabling vertigo and poor residual hearing, footplate decompression appears to be one of the most simple safe and effective surgical procedures.

Humans↗
PubMed1991

[Sellar germinoma with lung metastases].

Reported in this paper is the case of a boy aged 15 years with sellar germinoma which led to one singular pulmonary metastasis, three years after subtotal surgical removal and subsequent successful irradiation of the tumor rest. The primary tumor together with the lung metastasis were characterised as germinoma with trophoblastic giant cells as additional elements. Interpretation of the pulmonary tumour was somewhat difficult, since diagnosis of the primary tumor had encouraged assumption of a chromophobic hypophyseal adenoma with polymorphic manifestation, with no relationship between the intracranial and pulmonary tumors being presumed by the surgeon. The true nature of the metastasis and, consequently, the histogenetic identity of both tumors was cleared up by immunohistochemical detection of beta-HCG in almost all syncytiotrophoblasts. Comprehensive analysis of the literature on metastasising intracranial germinomas may be helpful in disclosing possible relationships between the histological type of a primary tumor or neurosurgical action and the metastatic potential of tumors.

Adolescent↗
PubMed1990

[Cushing's syndrome in CRF-producing mediastinal carcinoid].

A 36-year-old patient developed marked pigmentation, marked myopathy and severe hypokalaemic alkalosis which at first pointed towards an ectopic ACTH syndrome. The dexamethasone test at a high dose indicated cortisol suppression. A mediastinal tumour was seen radiologically, but the sella was of normal size. Computed tomography provided indirect signs of a sellar space-occupying lesion which suggested an ectopic production of corticotropin-releasing factor (CRF) as cause of the Cushing's syndrome. CRF concentration in antecubital venous blood was markedly elevated to 280 ng/l. The mediastinal tumour was excised and proved to be a carcinoid histologically. Postoperatively the CRF concentration fell to 70 ng/l. An extract of the carcinoid contained 15.5 ng/g wet-weight of CRF and 254 ng/g wet-weight of beta-endorphin. The patient died 5 weeks postoperatively of sepsis with bilateral pneumonia. At autopsy the hypophysis was of normal size but showed nodular ACTH-cell hyperplasia. This was thus a case of Cushing's syndrome resulting from ectopic CRF production in a mediastinal carcinoid tumour.

Adult↗
PubMed1990

Disulfide bridge formation between C1q and IgG in vitro.

The globular heads of C1q are known to possess free-SH groups. Here we show that these groups, which are concealed in the native molecule, are exposed by interaction of C1q with dialysis membrane. During iodination, I+ and I2 oxidize these sulfhydryls to produce disulfide-linked C1q aggregates. Approximately 15% of C1q bound to immunoglobulin aggregates is resistant to high conductivity elution and reducing agent is required to release it. These data show that dialysis, adsorption to Ig and iodination of C1q result in structural and functional changes in the molecule, and suggest a mechanism by which these changes occur. Disulfide bridging between C1q and IgG in vitro suggests that this may be a normal physiological function of C1q for which the free cysteines of human, mouse and guinea pig C1q have been conserved.

Animals↗
PubMed1990

Photoelastic stress comparison of warm (Endotec) versus cold lateral condensation techniques.

Stress generated during gutta-percha obturation of root canals can create microcracks and ultimately lead to failure. A new thermosoftening device, the Endotec, which develops a warm lateral condensation technique, was tested against the traditional lateral condensation procedure. The results indicated that the warm lateral condensation technique created less stress during obturation than did cold lateral condensation.

Cold Temperature↗
PubMed1990

High tech root canal preparation and obturation and new instrumentation.

With the use of the CAVIENDO and the ENDOTEC, and the improved instruments; the calibrated M SERIES PLUGGER/SPREADERS and new ENDO DIAMOND ACCESS BUR, a high-tech biologic approach to endodontic therapy has been developed that allows the operator to perform root canal treatment efficiently, effectively and with ease, achieving the highest degree of success.

Gutta-Percha↗
PubMed1990

[Psychologic factor in Menière's disease].

Although a number of authors have evoked a psychosomatic etiology for Ménière's disease, few works have dealt specifically with this subject. Forty-eight patients with authentic Ménière's disease underwent a series of psychometric self-evaluation determinations, in addition to a complete, repeated ENT examination. The first questionnaire, the SCL 90, explored the psychological profile. The second questionnaire, the QD 2 A, explored the depressive tendency. This study clearly showed that patients with Ménière's disease present a psychopathological profile which significantly differs to that of a reference population, particularly in terms of level of anxiety, depressive tendency and phobia. The latter points are of real practical importance, since they imply that improvements in Ménière's disease call for treatment of the phobic component in addition to the anxious-depressive component. Finally, there is an obvious correlation between the extent of hearing loss, in turn related to the frequency of vertigo attacks, and the severity of psychopathological disorders.

Adult↗