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Biomedical subjects

I Jonas

Publications and source records attributed to I Jonas.

9 recordsLinked to original sources
PubMed1992

Collagen stabilization induced by natural humic substances.

Humic substances are polyphenolic compounds. They have antiviral as well as desmutagenic effects and react with biopolymers such as collagen; thereby they have no toxic side effects by oral administration. In vitro incubation with humic substances raises the breaking point of the tail tendon of the rat by about 75%. The chemical resistance of the collagen fibres in tail tendon collagen is also increased by in vitro incubation with humic substances, at least insofar as the ultrastructurally and biophysically measurable destruction of the collagen fibres by 4 M guanidinium chloride is inhibited. As humic substances increase the mechanical and chemical resistance of collagen fibres and promote their "maturity", it seems likely that this effect of humic substances depends upon their interaction with the hydrogen bonding and covalent bonding of the collagen fibres. Such a conclusion is confirmed by the results of X-ray diffraction analysis.

Animals↗
PubMed1991

[Integrated and frequency spectra of the electromyograms in patients with temporomandibular symptoms].

With the aid of bipolar surface electrodes, the electromyographic activity of the anterior temporal and the superficial masseter muscles were recorded bilaterally and evaluated by counting the integrated potentials and mean power frequency using Fourier's analysis. A comparison between 17 patients with myofacial pain dysfunction (average age 21.3 years) and a group of 20 controls (average age 20.5 years) revealed a significantly greater activity in patients with pain syndrome, while no significant inter-group difference in mean power frequency was seen. The differences in the level of activity between the right and left sides in the control group were significantly smaller than in patients with pain dysfunction. An investigation of measures aimed at reducing the right/left asymmetry in a further 14 patients with pain dysfunction revealed the practice of "maximum occlusion with feedback" to be the most effective measure.

Adolescent↗
PubMed1978

Relationship between tubal function, craniofacial morphology and disorder of deglutition.

26 children without hearing impairment have been examined by otolaryngologists and orthodontists. According to the tubal function test in a pressure chamber they were classifed into a group with good and poor tubal function. The E.N.T. examination was unconclusive for a possible relationship between rhinological findings, mode of breathing, sinusitis, size of tonsils, nasal airway resistance and tubal function. Adenoids proved to be a mechanical impairment for active tubal function as stated by many authors. The cephalometric analysis of lateral head films combined with a static and dynamic-functional evaluation of tongue posture revealed significant differences between children with good and poor tubal function. Subjects with a vertical craniofacial growth pattern seem to be predisposed for poor tubal function. Analysing static tongue posture in children with poor tubal function the tongue lies more retracted in a backward position. The back of the tongue is flattened in relation to the palatal arch. In children with good tubal function there is a much closer contact between the back of tongue and the hard palate. Subjects with poor tubal function have an increased incidence of abnormal deglutition combined with tongue-thrust, teeth-apart swallowing, lack of sealing off the anterior oral cavity and contraction of the circumoral musculature. In children with good tubal function one can find the somatic type of swallowing that means no contractions of the circumoral muscles, no tongue-thrust during deglutition but contact of the molars and contraction of the masseter muscle.

Airway Resistance↗
PubMed1976

[Misleading x-ray diagnosis due to maxillary sinus asymmetries (author's transl)].

Asymmetries of the maxillary sinus with partial or total radiographic opacity mislead to the diagnosis of chronic sinusitis. Using three radiographic standard projections, computerised planimetric analysis and cephalometric studies helped to explain radiological opacity in 26 patients. So called "mucosal thickening" may be due to varying development of the zygomatic recess. Total opacity was caused not only by unilateral volume difference exceeding 30%, but also by straightning of the first lateral line in basal views of small and moderate sized sinuses. Cephalometric analysis in maxillary sinus asymmetry revealed ipsilateral transversal underdevelopment of facial- and skullbone. Reduced pneumatisation of the ethmoid, spenoid, mastoid and frontal sinus in diminishing order was also ipsilateral. Using photostat analysis there was nevertheless no correlation between facial- and coexisting maxillary sinus asymmetry.

Cephalometry↗
PubMed1976

[The influence of training on the accuracy of roentgenographic cephalometric tracings (author's transl)].

The accuracy in landmark identification and in the determination of angular and linear measurements used in cephalometric analysis on lateral head film were statistically evaluated comparing operators with different levels of competence. The observed magnitude of methodological error was depending on - prior experience of the investigator - individual radiographic anatomical knowledge - rigour of landmark definition and - accuracy of the tracing procedure. Considering these sources of error some of the variability in the present investigation might be avoided by systematic instructions. In order to decrease the variation in landmark location the reproducibility of some points must be further improved by redefining them in their verbal assessments. From an educational point of view the correlation between individual radiographic anatomical knowledge and the magnitude of error in cephalometric analysis should be considered with particular emphasis.

Cephalometry↗
PubMed1975

[Surgical methods for the correction of malocclusion Angle II/1 with postoperative prosthetic rehabilitation].

The operating methods for Angle class II, 1 are described and a method developed in which a front teeth block segment in the maxilla is raised and palatally tilted. At the same time a front and lateral teeth block segment of the lower jaw is pushed forward and lowered. The method improves the profile as well as occlusion and requires only a minimum of prosthetical care.

Humans↗
PubMedDate not supplied

Growth influence on tubal function.

The influence of growth on tubal function was studied in 26 children by means of tubal function tests in a pressure chamber and by geometric analysis of lateral cephalograms. Good tubal function coincided with mesoor brachycephalic skeletons, poor tubal function with dolichocephalic morphologic patterns. According to our results, tubal function seems to be strongly influenced by the growth processes of the skull.

Cephalometry↗