PubMed Health⌕ Search

Biomedical subjects

D Ram

Publications and source records attributed to D Ram.

53 records · Page 3Linked to original sources
PubMed1979

Deletions, rearrangements and tandem duplications of recombinant plasmids containing yeast ribosomal DNA.

Recombinant DNA plasmids, formed by the insertion of yeast ribosomal DNA into Escherichia coli plasmids pSC101 or pMB9, underwent deletions, rearrangements and tandem duplications. Independently derived deletion products of plasmids, constructed using pMB9 as a vector, are indistinguishable from each other. These deletion products from multimers composed of tandem repeats. In at least one case a plasmid, constructed by inserting an SmaI fragment of yeast ribosomal DNA into pSC101, underwent deletion and rearrangement to form a product in which a segment, consisting of part of the pSC101 sequence and part of the yeast ribosomal DNA sequence, was duplicated to form a tandem repeat. Deletion and rearrangement take place in Rec+, recA- and recB- recC- cells. The rate of deletion in Rec+ cells is higher than in recA- cells. The rate of deletion in minicell-producing, X-ray resistant strains is much higher than in other Rec+ strains.

Chromosome Deletion↗
PubMed1978

Deletions within E. coli plasmids carrying yeast rDNA.

Deletions occur in recombinant DNA plasmids that contain yeast ribosomal DNA (rDNA) inserted into the E. coli plasmids pSC101 and pMB9. Deletions within a pMB9 plasmid containing an insert longer than one tandem rDNA repeat apparently are due to homologous recombination because (1) all of the independently derived deletion products of this plasmid lost one complete rDNA repeat (8.6 kb) and retained only a single copy of the segment repeated at the ends of the original insert and (2) deletions were detected only when the insert had terminal redundancy. Deletions also occur within a pSC101 plasmid containing a tandem duplication of a segment (4.7 kb) including both pSC101 DNA and rDNA. Once again these deletions appear to be due to the presence of a duplicated region because all deletion products have lost one complete repeat. Deletions within both of these plasmids took place in both rec+ and recA- host cells, but occurred more frequently in rec+ cells. Oligomerization of the deletion products also occurred in both hosts and was more frequent in rec+ cells.

DNA↗
PubMed1975

Zero-trans and equilibrium-exchange efflux and infinite-trans uptake of galactose by human erythrocytes.

1. The zero-trans and equilibrium exchange efflux and the infinite-trans uptake of galactose in human erythrocytes were measured as a function of galactose concentration at 20 %. 2. The zero-trans procedure with cells loaded with 285 mM galactose revealed a low affinity site for galactose transport at the inner face of the membrane having a maximal velocity of 255 plus or minus 96 mmol/l isotonic cell water and Km equals 240 plus or minus 57, the V/K ratio being 1.01 plus or minus 0.04 min-1. 3. The equibirum-exchange procedure yielded a maximal velocity of 432 plus or minus 44 mmol/cell unit per min and K equals 138 plus or minus 57, the V/K ratio being3.19 plus or minus 0.52 min-1. 4. The infinite-trans uptake revealed a high affinity site at the outer face of the membrane having a maximal velocity of 239 plus or minus 11 mmol/cell unit per min, and K equals 21 plus or minus 2 mM. 5. These results combined with previous findings (Ginsburg, H. and Stein, W. D. (1975) Biochim. Biophys. Acta 000, 000-000) force us to reject the following models for sugar transport in human erythrocytes: a single asymmetric carrier; two symmetric carriers in parallel, the original form of the internal transfer model.

Biological Transport, Active↗
PubMedDate not supplied

The effect of metoclopramide and hydroxyzine in sedation of infants undergoing dental treatment.

The purpose of the present study was to determine whether the administration of 5 mg of the anti-emetic drug metoclopramide (MTP) would improve the effectiveness of 3.7 mg/kg of hydroxyzine (HYZ) in dental treatment of young patients. Thirty uncooperative children, with a mean age of twenty-nine months, and needing at least two restorative visits, participated in this study. The patients were assigned randomly to receive either 3.7 mg/kg HYZ or the same drug in conjunction with MTP; alternate regimens were administered at the two appointments. All the children received 50 percent nitrous oxide, and were restrained in a Papoose Board with a head holder. The following parameters were evaluated at baseline (before initiation of treatment), and at five-minute intervals throughout the procedure: degree of alertness, crying and movement. Evaluation of the overall behavior at each session was performed by one investigator, who was blind to the drug regimen the child had received, utilizing a separate rating scale. The results were submitted to statistical analysis. No differences were observed in the behavior of the children receiving both regimens. Successful sedation, as assessed by lack or minimal crying and/or movement was observed in all the treatment visits, with both regimens (mean score 4.4 for HYZ + MTP and 4.6 for HYZ). In the few occasions, however, where the restorative sessions were longer (45 to 60 minutes), more children fell asleep after receiving protocol A (pramin + hydroxyzine), suggesting a possible trend to improve effectiveness in these situations. No adverse effects were observed, and all the treatments were successfully completed. Although no significant differences could be observed in treatments lasting up to a half hour, the addition of MTP could help in sedations lasting longer than a half hour.

Anesthesia, Dental↗
PubMedDate not supplied

Sequelae and prognosis of intruded primary incisors: a retrospective study.

PURPOSE: This study was designed to assess the sequelae and prognosis of intruded primary incisors. METHODS: Of 196 children who visited the emergency clinic due to intrusion of 310 maxillary primary incisors, 110 children (172 teeth) were available for follow-up examination (study group). Eighty-six children (138 teeth) did not show for the follow-up examination (non-respondents group). Male/female ratio was 1.7:1. Age range of children at time of injury was 12-72 months (mean 28). Follow-up time ranged between 0 and 59 months (mean 27). RESULTS: Fifty-seven percent of all teeth were completely intruded. In 80%, the root was pushed labially. All but two ankylosed teeth re-erupted, and 37% of these re-erupted into an ectopic position. Completely intruded incisors re-erupted into an ectopic position in a higher percentage (45%) than partially intruded teeth (30%). Fifty-two percent of the teeth presented pulp canal obliteration (PCO). Sixty-four percent of the completely intruded incisors presented PCO compared to 40% of partially intruded teeth. Arrest of dentin apposition was found in 15% of the teeth, and was not affected by the degree of intrusion. Twenty-three teeth were extracted shortly after the injury due to suspect of contact with the developing permanent successor (19 teeth) and severe caries (4 teeth). Sixty-eight percent of the intruded teeth survived more than 36 months after the injury. Twenty-three percent were extracted due to periodontal breakdown and 5% due to repeated trauma. Antibiotic therapy did not have any effect on the survival rate. CONCLUSION: The majority of intruded primary incisors may re-erupt and survive with no complications after more than 36 months post trauma even in cases of complete intrusion and fracture of the labial bone plate.

Age Distribution↗
PubMedDate not supplied

Clinical performance of esthetic posterior crowns in primary molars: a pilot study.

PURPOSE: The aim of this pilot study was to assess the clinical performance of esthetic crowns and to compare these to conventional stainless steel crowns (SSC). METHODS: Twenty two crowns (11 conventional and 11 esthetic) were placed in mandibular primary molars obeying the following criteria: the tooth was not mobile; no fistulae were present; the tooth had at least one caries free or properly restored antagonist and had to be in contact with one adjacent tooth mesially, in the case of the primary second molars or distally in the case of the primary first molars. Crown preparation was done in a conventional manner, but reduction was more extensive for the thicker esthetic crowns, to allow for proper occlusion. The crowns were evaluated clinically and radiographically after 6 months and the following parameters were assessed: gingival health, marginal extension, crown adequacy, proper position or occlusion, proximal contact, chipping of the facing (for esthetic crowns) and cement removal. RESULTS: At the 6 month evaluation all esthetic crowns were intact, without chipping of the facing, and no excess of cement was observed in both groups. No difference was found for marginal extension, occlusion, proximal contact, crown adequacy, and bone resorption, but a significant difference was found for periodontal health between esthetic crowns and conventional SSC (P < 0.001 McNemar test). CONCLUSIONS: The esthetic crowns assessed had several inconveniences, as they resulted in poor gingival health, are very expensive, and, although not measured, are bulky and without a natural appearance.

Cementation↗
PubMedDate not supplied

Tongue piercing and insertion of metal studs: three cases of dental and oral consequences.

"Body art" is a fashion that appears to be gaining popularity worldwide. There are many risks and potentially adverse results associated with tongue piercing. Pain (the procedure is performed without anesthetics), post-placement edema and the risk of prolonged bleeding, if the blood vessels are punctured during the piercing, and fracture of tooth structures, are but a few of the risks. The purpose of the present article is to describe the consequences of three cases of tongue piercing in which metallic barbell-shaped studs were inserted: the consequences include the fracture of tooth structure, caused by the device knocking against the teeth; and inflammation and edema occurred as a result of the piercing of the tongue.

Adolescent↗
PubMedDate not supplied

Reactions of children to maxillary infiltration and mandibular block injections.

PURPOSE: The purpose of this study was to assess children's reactions to the administration of local anesthetic injection in the mandible and in the maxilla, and to study their sensation of pain after each type of injection. METHODS: Twenty-six children between the ages of 4 to 6 (mean age 5.3+/-0.7 years), and 34 children aged between 7 to 10 (mean age 8.1+/-1.1 years,) who were undergoing dental treatment in a pediatric dental clinic, were selected for this study. A random crossover design was used. Each patient was randomly assigned to receive either maxillary infiltration or mandibular block on the first visit, and the remaining local anesthesia on the second visit. During the injection, the modified Behavioral Pain Scale, was used. It comprised the following parameters: a) facial display, b) arm/leg movements, c) torso movements, and d) crying. Immediately after administering the local anesthesia, children were asked to rate their feeling according to the Facial Affective Scale. RESULTS: The children in each group responded positively to both techniques revealing that there was no difference in either one. Subjective and objective evaluation disclosed no difference when mandibular block was administered during the first or second visit. Regarding the objective evaluation, in all parameters, more children reacted positively during administration of mandibular block than during maxillary infiltration. CONCLUSION: a) mandibular block and maxillary infiltration are similarly accepted by children when first administered, and b) children may feel inconvenience or pain and react by crying, yet may report a positive feeling in general.

Affect↗
PubMedDate not supplied

Assessment of two doses of intranasal midazolam for sedation of young pediatric dental patients.

The purpose of this study was to assess the effectiveness of two doses of intranasal midazolam on sedation of young children for dental treatment. Thirty uncooperative children, mean age of 32 months, who needed at least two restorative visits, participated in this study. The patients were assigned randomly to receive either 0.2 mg/kg or 0.3 mg/kg of midazolam intranasally, with the alternate regimen administered at the second appointment. All the children received 50% nitrous oxide, and were restrained in a Papoose Board (Olympic Medical Group, Seattle, WA) with a head holder. Degree of alertness, crying, and movement were evaluated at baseline and at 5-min intervals throughout the procedure. Evaluation of overall behavior at each session was performed by one investigator, blind to the dose, using a separate rating scale. The reliability of ratings was assessed by two investigators from videotapes of the procedures. Statistical analysis showed no differences (P > 0.05) in the behavior of the children receiving the two doses. Successful sedation, as assessed by lack of or minimal crying and/or movement that interrupted treatment, was observed in all the treatment visits with both doses (mean score 4.66 +/- 1.09 for 0.3 mg and 4.40 +/- 1.04 for 0.2 mg). No adverse effects were observed, and all the treatments were completed successfully.

Administration, Intranasal↗
PubMedDate not supplied

Partial pulpotomy in a traumatized primary incisor with pulp exposure: case report.

Crown fracture with pulp exposure in primary incisors is a rare condition. Despite the fact that the vitality of the pulp can be preserved, such teeth are usually extracted due to lack of patient cooperation. This article reports a successful conservative treatment of a fractured primary incisors with pulp exposure and undeveloped root. The child was sedated with midazolam and nitrous oxide, and partial pulpotomy was performed using calcium hydroxide. Follow-up radiographs 21 weeks later revealed closure of the apex and apposition of a dentin bridge close to the amputation site.

Calcium Hydroxide↗
PubMedDate not supplied

The composition of subgingival microflora in two groups of children with and without primary dentition alveolar bone loss.

The is study examined the relationships between the microbial composition of the subgingival plaque, contact loss caused by caries and alveolar bone loss (ABL) in primary molars. The study included 10 children with contact loss in at least two sites, one with ABL and one without ABL, and 10 children without ABL with sites with or without contact loss. The microbial composition of subgingival plaque was examined by dark-field microscopy and by cultures of total anaerobic bacteria, Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg). Dark-field microscopy confirmed that spirochetes and motile rods may be part of the indigenous flora of the oral cavity. More spirochetes and motile rods were observed in sites with ABL than in control sites in the same subject and control subjects without ABL. Lower numbers of cocci were seen in sites with ABL than in sites in children without ABL, but a significant difference was not observed between sites with ABL and healthy sites within the same subjects. No significant differences in the dark-field values were evident in sites without ABL, with or without contact loss. Aa and Pg were found in children and sites with or without ABL. In sites with Aa, larger proportions of spirochetes, lower values of cocci, and more colonies of Pg were evident. No significant differences in anaerobic bacteria were evident between sites with or without contact loss or with or without ABL. ABL in the primary dentition was found to be related to the microbial composition of the subgingival plaque, but not related to contact loss per se.

Aggregatibacter actinomycetemcomitans↗