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PubMedDate not supplied

Disturbances in the oral cavity in pediatric long-term survivors after different forms of antineoplastic therapy.

Oral health and disturbances in dental development were studied in long-term survivors after antineoplastic therapy. Fifty-seven children treated with combination chemotherapy and 19 children treated with total body irradiation (TBI) prior to bone marrow transplantation (BMT) were examined. The variables studied were dental caries, salivary flow, salivary microbial counts, enamel disturbances, and disturbances in dental development. The results showed no increased caries experience in children treated with BMT or chemotherapy compared with controls. Children treated with BMT had a significantly lower salivary secretion rate of 0.7 +/- 0.4 ml/min, compared with 1.1 +/- 0.5 in the chemotherapy group, and 1.3 +/- 0.6 in the control group (P < 0.05). The clinical examination showed equal numbers of teeth affected by disturbances in enamel mineralization in the BMT and chemotherapy groups. A mean 15.9 +/- 8.2 teeth were affected by disturbances in root development in the BMT group compared with 1.2 +/- 1.6 in the chemotherapy group (P < 0.001). The results show that children who are long-term survivors of pediatric malignant diseases exhibit a wide range of disturbances in the oral cavity. In this study the most severe disturbances are found in children treated with total body irradiation prior to BMT.

Antineoplastic Agents↗
PubMed1987

Redistribution of Schwann cells in developing feline L7 ventral spinal roots.

The length and distribution of Schwann cells along fibres in the ventral root L7 of the developing cat have been studied electron microscopically in serial sections. The average Schwann cell length at the beginning of myelin formation - the 'initial internodal length' - was 118 micron (110 micron in alpha-axons and 124 micron in gamma-axons). The number of Schwann cells found in a fully developed root segment was already present at the beginning of the myelination. It showed no systematic age-dependent variation from the beginning of myelination to adulthood. The Schwann cells associated with alpha-axons increased their length 12.6 times during this period, while the root elongated 5.6 times. About 50% of the Schwann cells had to be eliminated in order to make the elongation of the remaining Schwann cells possible. Corresponding calculations from the mean length of Schwann cells associated with gamma-axons, showed that about 50% too few Schwann cells were associated with the gamma-axons during the period of initial myelination of the alpha-axons. At birth, when the myelination of gamma-axons had just begun, both the large surplus along alpha-axons and the deficit along gamma-axons had disappeared. We suggest that Schwann cells are eliminated from the alpha-axons and re-utilized along the gamma-axons. During this process of cellular redistribution, affected cells constitute so-called aberrant Schwann cells.

Age Factors↗
PubMed1990

A radiographic four-year follow-up study of asymptomatic mandibular third molars in young adults.

Fifty-five asymptomatic mandibular third molars (M3) in 34 dental students (mean age 20.6 years at the start of the study) were followed radiographically for 4 years. Based on clinical evaluation the 55 teeth included 20 almost erupted, 13 partly erupted and 22 non-erupted M3. The following were assessed on the radiographs: root development, level of eruption, sagittal angulation, resorption, pericoronitis/bony pockets/paradental cysts and widening of the periodontal space/dentigerous cysts. The state of 21 teeth (38 per cent) was radiographically changed at the end of the observation period. The most remarkable finding was that 15 teeth changed their sagittal angulation, all in a distal direction; five mesioangular to vertical, five vertical to distoangular, five mesioangular to distoangular. Radiographically, 13 M3 moved to a more advanced level of eruption. No real pathological osseous lesions and no root resorption were observed at initial or follow-up examinations. It is concluded that there are frequent essentially unpredictable changes in the position of M3 after the age of 19 years which may influence decisions on their removal or preservation.

Adult↗
PubMed1982

Canine eruption into grafted bone in maxillary alveolar cleft defects.

Forty-six patients with clefts of the alveolus who had received alveolar bone grafts (secondary osteoplasties) at ages 7-14 years, were studied. A total of 64 affected canines from 18 bilateral and 28 unilateral alveolar cleft patients was available. Follow up orthopantomographs were examined to determine the state of root development and spontaneous canine movement through the grafted site. The postoperative observation period ranged from 2-8 years (mean 4.3 +/- 1.5). All test canines erupted through the graft. Spontaneous eruption occurred for 27% of test canines, 17% required surgical uncovering (either bony or soft tissue), and 56% required surgical uncovering and orthodontic assistance to accomplish eruption. All patients required orthodontic treatment to accomplish arch alignment. The prognosis for canine eruption through a graft site is most favorable if the graft is performed at 1/4-1/2 canine root formation and when the patient is aged 9-12 years. The post graft observation period is very important and requires complete cooperation between the orthodontist and the surgeon.

Adolescent↗
PubMed1988

Re- and allotransplantation of teeth--an experimental study in monkeys.

In each of six monkeys one of the permanent lateral incisors with uncompleted root development was replanted. At the same time the contralateral incisors in four of the monkeys were allotransplanted by pairs. The remaining two contralateral incisors served as controls. After 4 weeks and 4 months, respectively, three monkeys were decapitated and the upper lateral incisors with adjacent periodontal tissue were examined histologically. The replanted teeth in five cases had a vital pulp. In the sixth case, however, the replanted incisor exhibited pulpitis and partial necrosis of the pulp. The periodontal membrane had a normal histologic appearance. In two cases a small area of arrested root resorption was observed. With the allotransplanted teeth the histologic appearance was altered. After 4 weeks a pronounced inflammatory reaction was observed in both the pulpal tissue and the periodontal membrane. The pulp was in most cases necrotic, and marked root resorption was observed. Most of the allotransplanted teeth were resorbed and replaced by an irregular hard tissue that resembled osteoid, which in many cases was connected with the tooth remnants by ankylosis. These results indicate that allotransplanted teeth, in contrast to replanted teeth, exhibit the characteristic features of an allograft rejection, including an inflammatory reaction and resorption.

Animals↗
PubMed1990

[Study of dental maturity in children aged 3-16 years in Chengdu].

Dental maturity was studied in a group of 903 healthy children (boys: 465, girls: 438) born in Chengudu from 1972 through 1988. Dental maturity was estimated by the method of Demirjian and Goldstein, which is based on the development of seven left mandibular permanent teeth; teeth formation was studied. The standard and curves of dental maturity for Chengdu children (boys and girls) were constructed. At 3-5 years old, boys had their dental maturity slightly earlier than girls; there was no significant difference between boys and girls (P greater than 0.05). At the age of 7-14, girls were more advanced than boys (P less than 0.05). Developmental curves of seven left mandibular permanent teeth were plotted. The sexual difference was smaller at the crown developmental stage, and it increased during the root development. In all, girls were more advanced by 0.45 year than boys. The maximum average difference was 0.85 year for the canine. The time that each developmental stage has taken was shorter in 50% of girls as compared with that in boys, and it was longer in 28% of girls. There was no difference between boys and girls in the remaining 22% of cases.

Adolescent↗
PubMed1984

Dental root agenesis secondary to irradiation therapy in a case of rhabdomyosarcoma of the middle ear.

There have been only a few published reports on the dental-facial effects of radiation therapy and the subsequent oral management of these patients. A case involving a 13-year-old black male patient with a history of rhabdomyosarcoma is presented. The patient received 4,050 rads of radiation to the right middle ear when he was 2 years of age. His residual medical and dental difficulties are apparently complications from the initial therapy. Examination of the oral cavity revealed bimaxillary micrognathia and marked loss of vertical dimension. A Class II facial profile with Class I molar relationship was observed. The mandible was thin and hypoplastic, with a small knife-edge alveolar ridge. The remaining eighteen erupted permanent teeth were very mobile, and root development had ceased after only initial formation. All of the teeth except the first permanent molars were extracted, and immediate partial dentures were inserted at the time of surgery. A discussion of therapeutic considerations follows the case report.

Abnormalities, Radiation-Induced↗
PubMed1992

The isolation and primary culture of putative human root odontoblasts.

The use of procedures adapted from a routinely successful method of culturing bovine bone has led to the first system for the study of dentinogenesis in vitro. Two types of cells have been grown from pulp obtained from the growing root tips of impacted third molars extracted from 14- to 19-years olds: (1) epithelial-like cells that are probably derived from fragments of the epithelial root sheath and (2) odontoblast-like cells. The cultured epithelial-like cells grow out in distinctive rounded plaques while the odontoblast-like cells are tethered to and/or grow on top of the epithelial-like cells. The odontoblast-like cells produce mineralized matrix by 10 days when cultured on a defined mineralization formula containing conditioned medium obtained from fetal bovine bone cell cultures. Growth factors in this conditioned medium are important to cell proliferation and growth and to the synthesis of mineralized matrix. Sequential enzyme digestion in dispase and dispase/collagenase in serum-free Dulbecco's Modified Eagle's Medium is essential to obtaining adequate cell yields from the apical 3-5 mm of the developing root. Reduction of the number of fibroblasts by treating cultures with dispase in Tyrode's solution midway through the initial growth period enhances the purity of these cell cultures.

Adolescent↗
PubMed1984

[Development of satellite-neuron relations in the spinal ganglia of the rat].

Cerebrospinal ganglia of 11-, 13-, 15-, 18- and 20-day-old embryos have been studied light- and electron-microscopically. On the 11th day of anlage the ganglia are presented exclusively as neuroblasts: the satellite-cells are formed later from lemmoblasts that install into the ganglion on the 13th-15th days both from the surrounding mesenchyme and from the developing roots and trunklets of the cerebrospinal nerves. In the ganglion they undergo proliferation and further differentiation. On the 15th day simple satellite-neuron interrelationships are formed: one satellite-cell is tightly connected with perikaryons of some neuroblasts and young neurons. On the 18th day around some neurons a double layered capsule is formed from the satellite-cells. Multilayered tunics are formed only on the 10th-15th day after birth. During the process of the capsule formation an unusual reactive character of the satellite-neuron interrelationships is revealed, it is manifested as, performed by the satellite-cells, an active microphagocytosis of the perikaryon cytoplasmic processes and the initial segment of the sensitive neuron main process. In embryogenesis the lemmocyte-axon interrelationships develop earlier than the satellite-neuronal ones.

Animals↗
PubMed1984

Four-year longitudinal study of the periodontal health status of overdenture patients.

Seven patients with a total of 12 roots were treated with overdentures (maxillary, mandibular, or both) and recalled at 6-month intervals for a period of 4 years. A periodontist evaluated the periodontal health status of the abutment roots after complete periodontal therapy, immediately prior to placement of the overdentures, and at all recall visits. The gingival tissues around all the abutments were slightly erythematous and edematous and bled on probing. There were no statistically significant changes in pocket depth or in apparent width of attached gingiva on an intra-arch basis. However, statistically significant changes were found on comparison between the maxillary and mandibular arches. Over the 4-year period 50% of the roots remained immobile, 25% of the roots that were initially mobile exhibited no mobility, and 25% of the roots decreased in mobility. Five of 14 roots in eight patients (35.7% of the abutment roots) developed dental caries. Periodic recalls to reinforce plaque control measures, to provide adjunctive periodontal therapy, and to correct and adjust the prostheses of patients treated with overdentures are important factors in the longterm success of this treatment modality. Biomechanically, treatment of patients with overdentures is a valid practical alternative to complete dentures.

Dental Abutments↗
PubMed1995

The maize Dwarf3 gene encodes a cytochrome P450-mediated early step in Gibberellin biosynthesis.

Gibberellins (GAs) are phytohormones required for normal growth and development in higher plants. The Dwarf3 (D3) gene of maize encodes an early step in the GA biosynthesis pathway. We transposon-tagged the D3 gene using Robertson's Mutator (Mu) and showed that the mutant allele d3.2::Mu8 is linked to a Mu8 element. The DNA flanking the Mu8 element was cloned and shown to be linked to the d3 locus by mapping in a high-resolution population developed by selecting for recombination between d3 and linked genetic markers. To establish unambiguously the identity of the cloned gene as D3, a second mutant allele of D3 (d3.4) was also cloned and characterized using the d3.2::Mu8 sequences as a probe. d3.4 was found to have a novel insertion element, named Sleepy, inserted into an exon. A third mutant allele, d3.1, which has the same size 3' restriction fragments as d3.4 but different 5' restriction fragments, was found to contain a Sleepy insertion at the same position as d3.4. On the basis of the pedigree, Sleepy insertion, and restriction map, d3.1 appears to represent a recombinational derivative of d3.4. The D3 gene encodes a predicted protein with significant sequence similarity to cytochrome P450 enzymes. Analysis of D3 mRNA showed that the D3 transcript is expressed in roots, developing leaves, the vegetative meristem, and suspension culture cells. We detected reduced D3 mRNA levels in the mutant allele d3.5.

Alleles↗
PubMed1992

[Results after short- and long-term observations of bone transplantation to vertical, marginal bone defects].

The effect of autologue bone transplantation to 26 vertical, marginal bone defects has been investigated on a long-term scale ranging from 2 to 26 years. The operation technique included excision of gingival pocket epithelium, removal of granulation tissue, and cleansing of the root surface with scalers. The bone cavities were filled preferably with cancellous bone chips, usually from the patients' upper third molar region. After suturing, the area was covered with a wound paste for 12-14 days. Loosened teeth were splinted for at least 2 months. In 25 of 26 teeth (96%) a bone regeneration was observed radiographically. The maximum healing of 22 cases occurred 2-12 months (median 6 months) postoperatively (Table 1). The maximum healing was maintained for more than half of the teeth (56%) at the last control, median 16 years (range 2-26 years), and none of these teeth were extracted of periodontal causes. They might therefore be expected to function for still a long time. Eight teeth (32%) showed more or less recurrence when controlled 5 to 15 years (median 10 years) after operation and 6 of the 8 teeth with recurrence were extracted. Three teeth (12%) developed root resorption and were extracted 6, 10 and 14 years postoperatively. As most of the complications occurred after extended observation periods, this factor has to be taken into account when prognosis of periodontal treatment procedure is considered.

Adult↗
PubMed1993

Immunocytochemical investigation of the rat cementoblast phenotype.

Recent studies have suggested that cementoblasts may be derived from osteoblast progenitor cells, although the cementoblast phenotype has not been extensively characterized. This immunocytochemical study was carried out to investigate the expression by rat cementoblasts of a number of proteins which are characteristic of the osteoblast phenotype. Paraffin sections from developing rat tooth germs and from fully formed adult rat teeth with surrounding tissues, were incubated with antibodies to type I & III collagen, osteocalcin, transforming growth factor beta (TGE beta), and insulin-like growth factor 1 (IGF1). Frozen sections and unfixed resin-embedded sections were stained for alkaline phosphatase activity. Cementum and bone matrix were strongly positive for type I collagen, although there was only weak staining for type III collagen. Cementum was also positive for osteocalcin, which was particularly strong in the matrix of acellular cementum. Most osteoblasts and cementoblasts of the cellular cementum showed intense staining for TGF beta and IGF1, although some cementocytes and osteocytes were negatively stained. The osteoblast- specific anti-E11 mAb reacted strongly with cementoblasts and newly formed cementocytes in the cellular cementum. Cells associated with acellular cementum did not express TGF beta, IGF1 or stain positively with anti-E11 antibody at any time during root development. Cementoblasts were weakly or negatively stained for alkaline phosphatase in contrast to the osteoblasts examined, which may reflect the low level of synthetic activity in cementoblasts. These results demonstrate that osteoblasts and cementoblasts of cellular cementum share many phenotypic characteristics, and also suggest that there may be phenotypic differences between cementoblasts associated with cellular and acellular cementum.

Animals↗
PubMed1990

Multiple functions for NGF receptor in developing, aging and injured rat teeth are suggested by epithelial, mesenchymal and neural immunoreactivity.

We have used immunocytochemistry to analyse expression of nerve growth factor receptor (NGFR) in developing, aging and injured molar teeth of rats. The patterns of NGFR immunoreactivity (IR) in developing epithelia and mesenchyme matched the location of NGFR mRNA assayed by in situ hybridization with a complementary S35-labeled RNA probe. The following categories of NGFR expression were found. (1) There was NGFR-IR in the dental lamina epithelium and in adjacent mesenchyme during early stages of third molar formation. (2) NGFR-IR nerve fibers were posterior and close to the bud epithelium. (3) During crown morphogenesis NGFR expression was prominent in internal enamel epithelium and preodontoblasts; it faded as preameloblasts elongated and as odontoblasts began to make predentin matrix; and it was weak or absent from outer enamel epithelium, the cervical loop, and differentiated ameloblasts and odontoblasts. (4) When NGFR-IR nerve fibers entered the molars late in the bell stage, they innervated the most mature peripheral pulp and dentin in an asymmetric pattern which correlated more with asymmetric enamel synthesis than with mesenchymal NGFR-IR distribution. (5) The mesenchymal pulp cells continued to have intense NGFR expression in adult teeth, especially near coronal tubular dentin. (6) The pulpal NGFR-IR decreased in very old rats or subjacent to reparative dentin (naturally occurring or experimentally induced). (7) During root formation, the preodontoblasts had NGFR-IR but most root mesenchymal cells and Hertwig's epithelial root sheath did not. This work suggests that there are important epithelial and mesenchymal targets of NGF regulation during molar morphogenesis that differ for crown and root development and that do not correlate with neural development. The continuing expression of NGFR-IR by pulpal mesenchymal cells in adult rats was most intense near coronal odontoblasts making tubular dentin; and it was lost during aging, or subjacent to sites of dentin injury that caused a phenotypic change in the odontoblast layer.

Aging↗
PubMed1993

HAT3.1, a novel Arabidopsis homeodomain protein containing a conserved cysteine-rich region.

Homeodomain proteins have been shown to play a major role in the development of various organisms. A novel Arabidopsis homeodomain protein has been isolated based on its capability to interact with a DNA motif derived from the light-induced cab-E promoter of Nicotiana plumbaginifolia. The homeodomain of this protein, designated HAT3.1, differs substantially from those in other plant homeobox proteins identified so far. Furthermore, HAT3.1 is unique among other Arabidopsis proteins in that it does not contain a leucine zipper motif following the homeodomain. HAT3.1 is further characterized by an N-terminal region that shares substantial sequence similarity with the maize homeodomain protein Zmhox1a. Within this conserved region, the presence of eight regularly spaced cysteine/histidine residues was observed reminiscent of other metal-binding domains. Based on the strong evolutionary conservation of this domain, it is proposed that this region represents a novel protein-motif which is denoted PHD-finger (plant homeodomain-finger). In vitro DNA binding studies demonstrated that HAT3.1 is capable of interacting with any DNA fragment larger than 100 bp. Interestingly, a deletion of the N-terminal PHD-finger domain completely abolished DNA binding, suggesting that this region may play an important functional role in protein-protein or protein-DNA interaction. HAT3.1 mRNA was primarily detected in root tissue, implying a regulatory function of this protein in root development.

Amino Acid Sequence↗
PubMed1994

Light inactivation of Arabidopsis photomorphogenic repressor COP1 involves a cell-specific regulation of its nucleocytoplasmic partitioning.

Arabidopsis COP1 acts as a repressor of photomorphogenesis in darkness, and light stimuli abrogate this suppressive action. COP1, when fused to beta-glucuronidase (GUS), is enriched in the nucleus in darkness, but not in the light, in hypocotyl cells of Arabidopsis seedlings and epidermal cells of onion bulbs. In Arabidopsis hypocotyl cells, the nuclear GUS-COP1 level changes in response to dark-light transitions and quantitatively correlates with the extent of repression of photomorphogenic development. In root cells, GUS-COP1 is constitutively nuclear, consistent with an established role of COP1 in suppressing root chloroplast development in both light and darkness. We conclude that COP1 acts inside the nucleus to suppress photomorphogenesis and that light inactivation of COP1 involves a cell type-specific control of its nucleocytoplasmic partitioning.

Allium↗
PubMed1991

Phenotypically normal transgenic T-cyt tobacco plants as a model for the investigation of plant gene expression in response to phytohormonal stress.

The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants. Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress.

Agrobacterium tumefaciens↗
PubMed1990

Electromyographic activity in the shoulder-neck region according to arm position and glenohumeral torque.

The electromyographical (EMG) response to isometric ramp contractions of the right arm, the left arm, and both arms was studied using four pairs of surface electrodes above the right upper trapezius muscle (UT) of six men and six women. Contractions were made against gravity with the active arm(s) in eight positions, ranging from flexion to abduction. To describe arm positions, new, simple terminology was developed. Root mean square (rms)-converted EMG-signals were normalized (EMGnorm) with respect to a reference contraction. The EMGnorm corresponding to a 15 N.m torque in the right glenohumeral (GH) joint was strongly related to the position of the right arm (P less than 0.001). The shape of this relationship depended on the electrode position (P less than 0.001). The ratio between EMGnorm at 30 N.m and 15 N.m GH torques was related to arm position (P less than 0.001) and differed between electrodes (P less than 0.001). A left-side GH torque resulted in right-side (contralateral) EMG activity, typically corresponding to 20%-30% of that obtained during similar right-side GH torque. Bilateral GH torque implied 0%-50% increase in EMG activity as compared to that obtained with the right arm alone. The results have shown that signals from one pair of surface electrodes above UT cannot be taken as representative of the EMG activity from electrodes located elsewhere above UT. The EMG recordings reflected a complex pattern of muscular activation, significantly related to both outwardly visible factors (arm position, GH torque), and within-body servosystems (motor control reflexes).

Adult↗