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Biomedical subjects

K Isotupa

Publications and source records attributed to K Isotupa.

At least 19 recordsLinked to original sources
PubMed2000

Distribution and characterization of proliferative cells in the rat mandibular condyle during growth.

Distribution of proliferative cells and localization of types I and II collagen were examined in the rat mandibular condylar cartilage of 36 long-Evans/Turku strain rats during normal postnatal growth using an immunohistochemical method combined with histomorphometry. There were considerable differences in the thickness of the proliferative cell layer in the condylar head, with most mitoses occurring in the postero-superior area. It was found that the extracellular matrix of the proliferative cells does not stain for type II collagen in 20-day-old and older rats, and that besides the subchondral bone, the strongest intensity for type I collagen stain was always localized in the articular surface of the condylar head. Statistically significant overlapping of the proliferative cell layer and the one secreting type II collagen occurred during the earlier stages of development, particularly in the postero-superior area of the condylar head. As type II collagen is considered to be a marker for identification of typical cartilage cells, the findings indicate that, in addition to undifferentiated cells, a portion of the proliferative cells can be characterized as chondroblasts during the early postnatal period in rats, but not in the later stages of development. The developmental phase of the condylar cartilage should therefore be taken into consideration when the effect of various biomechanical and humoral/hormonal factors on growth of the condylar cartilage is examined.

Animals↗
PubMed1998

A descriptive report of the effects of a 16-month xylitol chewing-gum programme subsequent to a 40-month sucrose gum programme.

A previous caries trial (Belize studies) involved the usage of sucrose chewing-gum for a period of 40 months in one group of initially 10-year-old subjects in an environment of high sugar consumption, high caries activity, and limited access to restorative care. After the termination of the 40-month supervised sucrose gum usage, the 109 subjects of the original sucrose group retrieved at the endpoint of the original trial were invited to participate in a xylitol chewing-gum programme (involving the usage of the '100% pellet-shaped formular') for 16 months. The average daily consumption level of xylitol was up to 14 g per subject, normally used in seven daily chewing episodes. Although most subjects used chewing-gum at schools and received their gum portions from a school official, gum chewing during these 16 months was mostly unsupervised. After 16 months, 83 subjects (76%; mean age 14.9 years) were retrieved. The caries status of these subjects was examined by the same calibrated, blinded examiners as in the original trial. To mask the examiners, 141 similar non-participating subjects were recruited from the same school classes and were examined in a random order with the gum-using subjects, according to the same standard routine. The intensified xylitol gum usage for 16 months was associated with a reduction of the mean DMFS score from 10.9 (at 40 months) to 9.3 (at 56 months, p = 0.0013) and a reduction in caries rate from 20.1 caries onsets per 1,000 surface-years (40-month period average rate) to 10.2 caries onsets per 1,000 surface-years. The reduction in DMFS score resulted mostly from the change in the D component of the index and possibly reflected a stabilisation of the caries process and rehardening of some caries lesions to a non-progressive carious state.

Adolescent↗
PubMed1991

Trabecular architecture of the mandibular condyle of the rat as revealed by vital staining.

The variability of the internal architecture of bone was studied in the mandibular condyle of young rats with the aid of vital staining capable of revealing bone trabeculae. The effect of season and age was observed in Spring- and Fall-born rats 28 and 56 days of age. There was no clear left-right asymmetry in the average direction of the condylar trabeculae, but their ranges of direction within the condyles exhibited such asymmetry. Both the average directions and the internal variability were different in the medial and the lateral sides of the condyles. There were also small but in most respects significant seasonal differences. These findings indicate that even the relatively small mandibular condyle of the rat is a very complex structure.

Aging↗
PubMed1991

The costochondral graft: a solution or a source of facial asymmetry in growing children. A case report.

Costochondral grafts are most commonly used to restore severely affected mandibular condyles in growing children. Despite their world-wide use, the growth of costochondral grafts can vary, excess growth being the most consequential problem. A report is presented her of a patient who sustained facial asymmetry to the left as a consequence of retarded growth in the left mandibular condyle. A costochondral graft was used to replace the left mandibular condyle at the age of 12 years 8 months, but six years after the operation the initially pleasing postoperative appearance had given away to facial asymmetry to the right. This was clearly due to the excess growth of costochondral graft. Possible aetiological factors, intrinsic, functional or both, affecting the growth of costochondral grafts are discussed.

Adolescent↗
PubMed1989

Shape of the craniofacial complex in 45,X females: cephalometric study.

The shape of the craniofacial complex was analysed cephalometrically in sixty-four adult 45,X females (Turner syndrome) using lateral skull radiographs, and the subjects were compared with first-degree female relatives and control females. The results showed that 45,X females have marked changes in relatively few craniofacial areas compared to the controls. Most of the changes are located in the cranial base, so that the face is retrognathic. The mandible is short, whereas the maxilla is of normal length. The results support the view that the morphology of the cranial base is markedly affected in 45,X females, whereas most other craniofacial changes could be considered secondary to the cranial base abnormality. It is suggested that retarded cartilage growth may be a factor leading to the present findings.

Adolescent↗
PubMed1981

Effect of alizarin red S on rat blood and its calcium content.

The vital staining mechanism of alizarin red S (ARS) was investigated. The total calcium content of rat blood was determined after intraperitoneal and intracardial administration of acidic, neutralized and calcium-supplemented ARS. The administration of ARS causes, irrespective of chemical state, a remarkable decrease in blood volume and a significant decrease in the serum/blood ratio. The total calcium content of rat serum was noticeably increased, more in the case of intracardial than in the case of intraperitoneal administration. The calcium values determined in this work were the sums of free and bound calcium. The increase in calcium content even in those cases where ARS was administered without calcium indicates a physiological ability to keep the concentration of free calcium constant in the blood. The highest calcium values were found when calcium-supplemented ARS was administrated. The physiological activity, however, seems to be higher with acidic ARS, which also contributed to the vital staining effect on rat skull. The best staining with least inconvenience was achieved using neutralized ARS for in vivo staining.

Animals↗
PubMed1980

Staining properties of alizarin red S for growing bone in vitro.

The pH-metric titration curve of alizarin red S (ARS) showed that ARS ionizes in three stages: firstly the -SO3Na group, secondly the beta-hydroxyl group, and finally on the alkaline side the alpha-hydroxyl group. The titration of ARS solution with calcium ions indicates that complex and chelate formation between ARS and calcium are distinct. The in vitro staining experiments were carried out at different pH levels. Completely ionized ARS had the best affinity for growing bone surfaces. The next most effective staining occurred just prior to neutralization. The least effective staining by ARS was found after the neutralization point had been reached. The presence of calcium made the dye solution inactive for staining the growing bone in vitro.

Animals↗
PubMed1977

Treatment planning from study models: an examiner variability study.

Four orthodontists of comparable but differing experience examined fifty sets of study models obtained from a random sample of 12 year-old schoolgirls. On the basis of these study models only, assessments were made of need for treatment, for timing, length and complexity of treatment. The degrees of agreement have been analysed and discussed.

Child↗
PubMed1977

Changes in the dentition of the guinea pig following total section of the inferior alveolar nerve and vessels.

The inferior alveolar nerve was cut or the vessels entering the mandibular canal were damaged in 39 guinea pigs at 10 days of age. Possible changes in the incisors were recorded during a 100-day observation period whereafter the animals were killed and the skulls freed of soft tissues; at this time, 35 skulls were found suitable for further examination. The changes in the mandibular incisors on the operated side became observable 30-40 days post-operatively as discolourization, a 'trauma line' around the tooth, narrowing of the tooth or total loss of it's visible part. In the guinea pigs with the nerve cut (group A), such signs of maldevelopment were seen in 5 out of 19 animals, whereas the corresponding figure for the animals with the damaged vessels (group B) was 14/16. All incisors in group A and 13 out of 14 in group B recovered from the state of maldevelopment; one animal in group B showed complete loss of the incisor. The molar region was examined only from the cleaned skulls. In group A, the first molar was deformed in two animals; in group B, seven animals displayed either maldevelopment of the first molar or the first and second molar or complete loss of the first molar. No malformation of the third molar was observed. With two exceptions, the deformation or loss of molars occurred in combination with incisor maldevelopment. The malformations were considered to result from a disturbed blood supply. In group A, the dental changes may perhaps be ascribed to a short-term interference with the blood supply during the operation. The variable results in group B seem to imply that the mandibular teeth receive at least part of their blood supply from vessels besides those entering the mandibular canal. The innervation appears to have a subordinate role in the restoring of the morphology of continuously erupting teeth.

Alveolar Process↗
PubMed1976

A note on craniofacial sutural growth.

The paper presents and discusses some features of sutural structures. Fibre orientation in sutures seems to be quite variable and associated with minute local growth phenomena. Trabecular patterns in bones, reflecting growth, appear to support the idea of the outside determination of growth. The bevelled and interdigitated structures seen in many sutures may be interpreted as an expedient solution to the problem of fast growth.

Animals↗