Biomedical subjects

S Ruf

Publications and source records attributed to S Ruf.

At least 19 recordsLinked to original sources

PubMed1999

Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: A prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.

The aim of this prospective study was to analyze and compare the temporomandibular joint adaptive mechanisms in 25 adolescent and 14 young adult Class II malocclusions treated with the Herbst appliance. Temporomandibular joint remodeling was analyzed by magnetic resonance imaging. In each subject, 4 magnetic resonance images of both temporomandibular joints were available: before treatment, at the start of treatment (when the Herbst appliance was placed), during treatment (6 to 12 weeks after appliance placement), and after treatment (when the appliance was removed). Furthermore, effective temporomandibular joint changes (the sum of condylar remodeling, fossa remodeling, and condyle-fossa relationship changes) were analyzed with the aid of lateral cephalometric radiographs from before and after treatment. All subjects were treated to Class I or overcorrected Class I dental arch relationships, and their mandibles became significantly (P <.001) more prognathic. After 6 to 12 weeks of Herbst treatment, signs of condylar remodeling were seen at the posterosuperior border in 48 of the 50 adolescent condyles and in 26 of the 28 young adult condyles. Bilateral remodeling of the mandibular ramus could be detected in 1 adolescent and 2 young adult patients. Signs of glenoid fossa remodeling at the anterior surface of the postglenoid spine were noted in 36 adolescent and 22 young adult temporomandibular joints. Effective temporomandibular joint changes during treatment were more horizontally directed and larger in both adolescents and young adult patients treated with the Herbst appliance than in an untreated group of subjects with ideal occlusion (Bolton standards). The increase in mandibular prognathism accomplished by Herbst therapy in both adolescents and young adults seems, in particular, to be a result of condylar and glenoid fossa remodeling. Because the Herbst appliance is most successful in Class II patients also at the end of the growth period, the treatment method could be an alternative to orthognathic surgery in borderline skeletal Class II cases. Magnetic resonance imaging renders an excellent opportunity to visualize the temporomandibular joint remodeling growth processes.

Adaptation, Physiological↗

PubMed1999

The compensatory mechanism in high-angle malocclusions: a comparison of subjects in the mixed and permanent dentition.

Dentoskeletal morphology was assessed in 191 untreated and unselected children with a hyperdivergent (high-angle) mandibular plane (ML/NSL > or =40 degrees) by analyzing lateral roentgenographic cephalograms. The subjects were divided into mixed dentition and permanent dentition groups, and further divided into subgroups based on the amount of overbite (OB) as a measure of dentoalveolar compensation of jaw base hyperdivergency: OB < 0 mm (openbite) = insufficient/no compensation; OB 0 to 4 mm (normal overbite) = acceptable compensation; OB > 4 mm (deepbite) = overcompensation. Openbite was observed in 20% of the children, normal overbite in 50%, and deepbite in 30%. Skeletally, the deepbite mixed dentition group was characterized by a relatively posterior inclination of the maxilla, while the deepbite permanent dentition group had a relatively anterior inclination of the mandible. Dentoalveolar compensation was accomplished by relative increases in maxillary and mandibular anterior dentoalveolar heights in the mixed dentition group and by relative decreases in maxillary and mandibular posterior dentoalveolar heights in the permanent dentition. Positive overbite was found in the majority (80%) of children with high-angle morphology. Thus, mandibular hyperdivergency is frequently compensated for. Skeletal characteristics and dentoalveolar compensatory mechanisms differ with dental maturity and seem to be influenced by mouth breathing and other oral habits.

Age Factors↗

PubMed1999

Dentoskeletal effects and facial profile changes in young adults treated with the Herbst appliance.

This prospective Herbst study analyzed the sagittal dental and skeletal changes contributing to Class II correction in young adults. Additionally, the alteration in skeletal and soft tissue convexity occurring during treatment was assessed. Early adolescent subjects in the permanent dentition who had been treated with the Herbst appliance were used for comparison. Lateral headfilms from before and after an average treatment period of 8.5 months for the young adults and 7.1 months for the adolescents were evaluated. All adult and adolescent subjects were treated to either Class I or overcorrected Class I occlusal relationships. In both groups the improvement in sagittal incisor and molar relationships was achieved more by dental changes than by skeletal ones. The amount of skeletal change contributing to overjet and molar correction was smaller in the young adult group (22% and 25%, respectively) than in the early adolescent group (39% and 41%, respectively). Skeletal and soft tissue facial profile convexity was reduced in adults and adolescents. Facial profile improvement did not differ between the two groups. The results of this study revealed that the Herbst appliance is most effective in the treatment of Class II malocclusion in young adults. It is suggested that this treatment method could be an alternative to orthognathic surgery in borderline Class II cases.

Adolescent↗

PubMed1998

The germinal center kinase (GCK)-related protein kinases HPK1 and KHS are candidates for highly selective signal transducers of Crk family adapter proteins.

Adapter proteins function by mediating the rapid and specific assembly of multi-protein complexes during the signal transduction which guards proliferation, differentiation and many functions of higher eukaryotic cells. To understand their functional roles in different cells it is important to identify the selectively interacting proteins in these cells. Two novel candidates for signalling partners of Crk family adapter proteins, the hematopoietic progenitor kinase 1 (HPK1) and the kinase homologous to SPS1/STE20 (KHS), were found to bind with great selectivity to the first SH3 domains of c-Crk and CRKL. While KHS bound exclusively to Crk family proteins, HPK1 also interacted with both SH3 domains of Grb2 and weakly with Nck, but not with more than 25 other SH3 domains tested. The interaction of HPK1 with c-Crk and CRKL was studied in more detail. HPK1-binding to the first SH3 domain of CRKL is direct and occurs via proline-rich motifs in the C-terminal, non-catalytic portion of HPK1. In vitro complexes were highly stable and in vivo complexes of c-Crk and CRKL with HPK1 were detectable by co-immunoprecipitation with transiently transfected cells but also with endogenous proteins. Furthermore, c-Crk II and, to a lesser extent, CRKL were substrates for HPK1. These results make it likely that HPK1 and KHS participate in the signal transduction of Crk family adapter proteins in certain cell types.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Long-term TMJ effects of Herbst treatment: a clinical and MRI study.

The long-term effects of the Herbst appliance on the temporomandibular joint were assessed in 20 patients (10 girls and 10 boys) who had completed treatment an average of 4 years previously. The TMJ analysis comprised of: (1) an anamnestic questionnaire (2) a clinical investigation (manual functional analysis) and (3) magnetic resonance imaging of the left and right joints. The results revealed that the incidence of anamnestic and clinical signs and symptoms of temporomandibular disorders was within the range of "normal" reported in the literature. The frequency of disk displacement was not higher than in asymptomatic populations. When summarizing the anamnestic, clinical and magnetic resonance imaging findings five subjects (25%) exhibited moderate to severe signs of temporomandibular disorders ranging from partial to total disk displacement or "deviation in form" of the condyle. Another three subjects (15%) showed mild symptoms of temporomandibular disorders with either small condylar displacement or subclinical soft tissue lesion. In conclusion, it can be said that Herbst treatment does not seem to have an adverse long-term effect on the temporomandibular joint.

Adolescent↗

PubMed1998

"Effective condylar growth" and chin position changes in Herbst treatment: a cephalometric roentgenographic long-term study.

In 98 Class II Division 1 malocclusions treated with the Herbst appliance "effective condylar growth" (a summation of condylar remodeling, glenoid fossa remodeling, and condylar position changes within the fossa) and its influence on the position of the chin was analyzed. Lateral head films in habitual occlusion from before and after 0.6 years of Herbst treatment as well as 0.6 years and 3.1 years posttreatment were evaluated. All patients were treated to Class I or overcorrected Class I dental arch relationships. During the treatment period, effective condylar growth was relatively more backward directed and about three times larger than that in untreated subjects with ideal occlusion (Bolton Standards). During the first posttreatment period of 0.6 years, effective condylar growth recovered with respect to both the direction and amount of changes. During the second posttreatment period of 2.5 years, effective condylar growth was "normal." The corresponding chin position changes during the different examination periods were a mirror image of effective condylar growth provided no mandibular autorotation occurred. In cases with anterior mandibular autorotation, relatively more forward and in cases with posterior mandibular autorotation relatively more backward directed chin position changes resulted.

Adolescent↗

PubMed1998

Does orthodontic proclination of lower incisors in children and adolescents cause gingival recession?

In this investigation we sought to assess the effect of orthodontic proclination of lower incisors in children and adolescents with respect to the possible development of gingival recession. Ninety-eight children with a mean +/- SD start-of-treatment age of 12.8 +/- 1.4 years, treated with the Herbst appliance, were surveyed, for a total of 392 lower incisors. Lateral head films, dental casts and intraoral photographs were analyzed with respect to the degree of orthodontic proclination, crown height, and gingival recession. In all subjects, Herbst treatment resulted in varying degrees of lower-incisor proclination (mean = 8.9 degrees, range = 0.5 degrees to 19.5 degrees). In 380 of the surveyed teeth (97%), either no recession developed or preexisting recession remained unchanged during Herbst therapy. In only 12 teeth (3%) did recession develop or preexisting recession deteriorate during treatment. No interrelation was found between the amount of incisor proclination and the development of gingival recession. In conclusion, orthodontic proclination of lower incisors in children and adolescents seems not to result in gingival recession.

Adolescent↗

PubMed1998

Temporomandibular joint growth adaptation in Herbst treatment: a prospective magnetic resonance imaging and cephalometric roentgenographic study.

The aim of this investigation was to analyze three possible adaptive TMJ growth processes contributing to the increase in mandibular prognathism accomplished by Herbst appliance therapy: (1) condylar remodeling; (2) glenoid fossa remodeling; and (3) condyle-fossa relationship changes. The subjects were 15 consecutive Class II malocclusions (11 males and four females, aged 11.5-17.5 years) treated with the Herbst appliance for an average period of 7 months. Condylar remodelling, glenoid fossa remodelling, and condyle-fossa relationship changes were analyzed by means of magnetic resonance imaging (MRI). From each subject, four MR images were evaluated: before treatment, start of treatment (when the Herbst appliance was placed), during treatment (6-12 weeks after appliance placement), and after treatment (when the appliance was removed). 'Effective condylar growth' (= the sum of condylar remodelling, fossa remodelling, and condyle-fossa relationship changes) was analyzed with the aid of pre- and post-treatment lateral cephalometric roentgenograms. In all 15 subjects, Herbst therapy resulted in an increase in mandibular prognathism. After 6-12 weeks of treatment MRI-signs of condylar remodelling were seen at the posterior-superior border in 29 of the 30 condyles. MRI-signs of glenoid fossa remodelling at the anterior surface of the postglenoid spine were noted in 22 of the joints. Condylar remodelling seemed to precede fossa remodelling. The condyle-fossa relationship was, on average unaffected by Herbst therapy. 'Effective condylar growth' during treatment was, on average, approximately five times larger in the Herbst group than in an untreated group with ideal occlusion (Bolton Standards) and the direction of the growth changes was relatively more horizontal in the treated cases. The results indicate that condylar as well as glenoid fossa remodelling seem to contribute significantly to the increase in mandibular prognathism resulting from Herbst treatment, while condyle-fossa relationship changes are of less importance. MRI renders an excellent opportunity to visualize temporomandibular remodelling growth processes.

Adaptation, Physiological↗

PubMed1997

Targeted inactivation of a tobacco intron-containing open reading frame reveals a novel chloroplast-encoded photosystem I-related gene.

The chloroplast genome of all higher plants encodes, in its large single-copy region, a conserved open reading frame of unknown function (ycf3), which is split by two group II introns and undergoes RNA editing in monocotyledonous plants. To elucidate the function of ycf3 we have deleted the reading frame from the tobacco plastid genome by biolistic transformation. We show here that homoplasmic Deltaycf3 plants display a photosynthetically incompetent phenotype. Molecular analyses indicate that this phenotype is not due to a defect in any of the general functions of the plastid genetic apparatus. Instead, the mutant plants specifically lack detectable amounts of all photosystem I (PSI) subunits analyzed. In contrast, at least under low light conditions, photosystem II subunits are still present and assemble into a physiologically active complex. Faithful transcription of photosystem I genes as well as correct mRNA processing and efficient transcript loading with ribosomes in the Deltaycf3 plants suggest a posttranslational cause of the PSI-defective phenotype. We therefore propose that ycf3 encodes an essential protein for the assembly and/or stability of functional PSI units. This study provides a first example for the suitability of reverse genetics approaches to complete our picture of the coding capacity of higher plant chloroplast genomes.

Chloroplasts↗

PubMed1997

Tissue-specific and differential editing of the two ycf3 editing sites in maize plastids.

The hypothetical chloroplast open reading frame 3 (ycf3) of maize, consisting of three exons and two group II introns, contains two editing sites. Both of these sites were investigated with respect to the extent of editing in various tissues and different developmental stages. Northern blot analyses show nearly identical transcript patterns of ycf3 in all tissues investigated. In leaf plastids, both editing sites are completely edited, independent of light conditions and developmental stage. In non-leaf plastids, however, one editing site of ycf3 is only partially edited in unspliced transcripts and in one type of partially spliced transcripts. In different developmental stages of the same tissue, on the other hand, no differences in editing efficiency were found. These results indicate that, in partially spliced transcripts, different editing sites of one and the same gene can be edited with different efficiencies in a tissue-specific manner.

Open Reading Frames↗

PubMed1997

The mechanism of Class II correction during Herbst therapy in relation to the vertical jaw base relationship: a cephalometric roentgenographic study.

This retrospective Herbst study analyzes and compares the sagittal dental and skeletal effects contributing to Class II correction in subjects with small or large pretreatment mandibular plane angles. Lateral headfilms of 15 hypodivergent (ML/NSL < or = 26 degrees) and 16 hyperdivergent (ML/NSL > 39 degrees) Class II subjects treated to a Class I occlusal relationship with the Herbst appliance were analyzed. Radiographs were taken before and after an average treatment period of 7 months. Cephalograms were evaluated according to the method of Pancherz. In both groups, impprovements in sagittal incisor and molar relationships were achieved by greater dental than skeletal changes. The amount of skeletal changes contributing to overjet and molar correction was larger in the hyperdivergent group (37% and 44%, respectively) than in the hypodivergent group (25% and 25%, respectively). Dental and skeletal changes contributing to Class II correction were found to be independent of the vertical jaw base relationship. Thus, a hyperdivergent jaw base relationship did not affect the treatment response unfavorably.

Adolescent↗

PubMed1997

Stress-induced changes in the functional electromyographic activity of the masticatory muscles.

The present study was undertaken to assess the effect of a non-experimental emotional stress situation on the functional electromyographic (EMG) activity of the masticatory muscles. The material comprised 15 dental students without signs and symptoms of disorders from the temporomandibular system. The activity of the masseter and anterior temporalis muscles was recorded bilaterally by means of surface EMG. The subjective degree of helplessness of the subjects was assessed and related to the EMG activity response, to assess a possible interrelation. The EMG activity during the stress situation was significantly greater than for the non-stress situation. This shift in EMG activity was seen for all the muscles and all the functions analyzed. No significant gender differences were found. When the subjective degree of helplessness is taken into consideration, women showed significantly higher ratings than male subjects. The Helplessness Scale ratings correlated with the changes in EMG activity.

Adult↗

PubMed1996

Corrective osteotomy for post-traumatic malunion of the phalanges in the hand.

Rotation, angulation, deviation, shortening or a combination of deformities can occur due to phalangeal malunion and can lead to impairment of hand function. A historical cohort study of 57 patients who had phalangeal corrective osteotomies for posttraumatic malunion between 1978 and 1990 was undertaken. 59 rotational, radial/ulnar deviation, flexion/extension, length adjustment procedures, and combinations thereof were performed, using rigid internal fixation. Concurrent tenocapsulolysis was done in 50% of the cases. Satisfactory correction was obtained in 76% of the patients. Bony union was obtained in all cases. A net gain in active range of motion was achieved in 89% of the patients. Excellent and good results were obtained in 96% of the patients who had corrective osteotomies for malunion involving only the bone and in 64% of the patients who had corrections for malunion with involvement of multiple structures (P < 0.01).

Adult↗

PubMed1996

Frontal sinus development as an indicator for somatic maturity at puberty?

The possibility of predicting the stage of somatic maturity by analyzing frontal sinus growth was evaluated. The study was performed on 53 adolescent boys, and the frontal sinus size development was assessed on lateral head films. The accuracy of the prediction procedure was tested by comparing the prediction stage with the longitudinal growth data for body height of the subjects. The results revealed that: If the only prediction was whether the pubertal growth peak in height has been passed (group B), the precision of the method was rather high (approximately 90%). However, if the age of body height peak was to be predicted, the method accuracy was lower (approximately 55%). No significant difference existed between the 1- and 2-year prediction intervals. The study suggests that the somatic maturity stage may be predicted rather accurately by analyzing frontal sinus development on pre-existing lateral head films.

Adolescent↗

PubMed1996

The effect of Herbst appliance treatment on the mandibular plane angle: a cephalometric roentgenographic study.

The purpose of this investigation was to assess the individual reaction pattern and the long-term effect of Herbst appliance treatment on the vertical jaw base relationship, as expressed by the mandibular plane angle (ML/NSL). In the evaluation special reference was given to the pretreatment vertical jaw base relationship (hypodivergent, normodivergent or hyperdivergent). Lateral head films of 80 patients (47 males and 33 females) from before, at start (when the appliance was placed) and at the end of Herbst treatment (when the appliance was removed) as well as 6 months and 4.5 to 5 years posttreatment were analyzed. The ML/NSL angle was on the average unaffected by Herbst therapy. Posttreatment, a continuous decrease in the ML/NSL took place. Male subjects showed a larger angular decrease than female subjects. However, a large interindividual variation existed. No statistically significant differences were found between hypodivergent, normodivergent, and hyperdivergent subjects.

Adolescent↗

PubMed1996

Development of the frontal sinus in relation to somatic and skeletal maturity. A cephalometric roentgenographic study at puberty.

The development of the frontal sinus in relation to somatic and skeletal maturity was analysed in 26 male subjects aged 9-22 years by means of longitudinal data obtained from lateral head films, handwrist radiographs and body height growth curves. These were grouped together and analysed in a cross-sectional manner. The results revealed that the final size of the frontal sinus varied considerably. Analogous to body height growth at puberty, the enlargement of the frontal sinus exhibited a similar pattern with a well-defined peak, which on average occurred 1.4 years after the body height peak. In comparison with skeletal maturity, 65 per cent of the subjects reached the sinus peak during the hand radiographic stages MP3-G or MP3-H, while the body height peak coincided with an earlier maturity stage (MP3-FG).

Adolescent↗

PubMed1996

Can frontal sinus development be used for the prediction of skeletal maturity at puberty?

The precision of a new procedure predicting skeletal maturity on the basis of frontal sinus development was tested in 59 boys with an Angle class-II division-1 malocclusion. Lateral head films were used for the analysis of frontal sinus development, and handwrist radiographs were used for the assessment of skeletal maturity. The results showed that skeletal maturity could be predicted with a certainty of about 85% when using a 1-year prediction interval and with a certainty of about 75% when using a 2-year prediction interval. In conclusion, the study showed that skeletal maturity can be predicted with rather high accuracy by means of the analysis of frontal sinus development as imaged on lateral headfilms.

Adolescent↗

PubMed1996

3-Methylidene-beta-lactams as potential inhibitors of beta-lactamases. Part 1: Synthesis of alpha-substituted derivatives from imines by Reformatzky reaction with chlorotrimethylsilane, silylation and Peterson olefination.

A new variation of the Reformatzy reaction with use of I2/zinc and chlorotrimethylsilane in THF and a shortened work-up is described allowing the synthesis of a wide variety of substituted beta-lactams 3 in fairly good yield. These lactams are silylated according to the Peterson reaction yielding by reactions with appropriate carbonyl compounds E/Z-mixturs of the substituted 3-methylidene beta-lactams 7, 8 and 10. The isomers are separated by CC and completely characterized by spectroscopic methods, mainly 1H NMR spectroscopy. Condensation of the 3-formyl methylidene derivative 10 with amines or malonate yields the conjugated products 11, and from the isopropylidene derivative 6 the pyridinium sulfonate 14 is prepared via 12 and 13. All methylidene beta-lactams are prepared as model compounds for studying their activity against beta-lactamases and for elucidating the mechanism of action.

Alkenes↗