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Biomedical subjects

A Becker

Publications and source records attributed to A Becker.

At least 451 records · Page 25Linked to original sources
PubMed1984

On the measurement of cranial thickness at nasion on cephalographs.

Cranial bone thickness at nasion is difficult to measure by the conventional method of drawing a line at right angles to the tangent at nasion on the outer table. The difficulty arises from a lack of uniformity of the arc in this region. The proposed use of a constructed line, drawn at 30 degrees to the anterior projection of the Frankfort horizontal plane, provides an accurate, easily reproducible, and compatible alternative method of measurement.

Adult↗
PubMed1984

The multistrand retainer and splint.

A method is presented for the accurate application of the modified 3-3 retainer of multistrand wire described by Zachrisson . This lingual retainer or splint is noninvasive of dental tissue and is reversible. Wire breakage does not appear to occur, and the slightly elastic properties of the wire allow a physiologic mobility of the teeth, which is of advantage in the periodontal patient. The only breakage that may occur is of the composite bond, although this appears to be less than with bonded brackets, but repair is quick and simple. The present method is now offered to add simplicity, speed, and accuracy to the important advantages already enjoyed, widening the scope for employment of this type of retainer to as many as eight or ten teeth in a series and, perhaps more significantly, to the maxillary anterior teeth, even where a deep bite exists. The value of the method is also seen when an active orthodontic appliance is removed and retention or splinting is required within an hour or two, as for the patient who is concurrently undergoing periodontal treatment.

Equipment Design↗
PubMed1984

Surgical exposure, orthodontic movement, and final tooth position as factors in periodontal breakdown of treated palatally impacted canines.

Twenty-three patients who had completed orthodontic treatment for the resolution of unilateral palatal canine impactions were examined 2.3 years (mean) after all appliances were discarded. The patients were divided into two groups on the basis of whether the surgical exposure was "light" or "heavy." The whole group was also divided according to the type of orthodontic movement that was carried out--"light" for tipping, extrusive, and rotating movements and "heavy" for root movements. Final position of the teeth was classified as ideal or incomplete if rotations or spaces were present. The results showed marked deteriorative changes where the surgery had been more radical and where the tooth movement involved active alteration of root position. No change due to abnormal tooth position was seen. It is suggested that, in these cases, surgical procedures be limited in scope and that exposure of the cementoenamel junction be avoided.

Alveolar Process↗
PubMed1984

Periodontal status following the alignment of buccally ectopic maxillary canine teeth.

Twenty-nine patients who had completed orthodontic treatment to resolve buccal displacement of maxillary canine teeth were examined 2.9 years (mean) after all appliances had been discarded. Thirteen of these patients had unilateral displacement, and sixteen were bilaterally affected. In the unilateral cases only the width of attached gingiva was significantly less than in the controls. In the bilateral cases the same observation was made, but here the gingival index and pocket depth also showed statistically significant increases, although the expression of these values was found to have doubtful clinical significance. Posttreatment periodontal assessment is recommended for these cases.

Adolescent↗
PubMed1984

Growth of Candida species in liquid culture medium for Trichomonas vaginalis.

The growth of Candida spp from vaginal specimens in Bushby's liquid medium for T vaginalis was compared with that on Sabouraud's agar medium, and isolation was significantly greater in Bushby's medium (p less than 0.001). Isolations missed (4.43%) in Bushby's medium probably represented vaginal carriage of small numbers of Candida spp.

Candida↗
PubMed1984

[Bioavailability of metoclopramide in a sustained-release preparation].

The aim of this study was to examine the pharmacokinetical behaviour of metoclopramide of Gastronetron retard capsules after a single administration to 8 healthy male volunteers. Determinations of the concentration of metoclopramide in the serum were made up to 24 h p.a. The calculation of the serum concentration curves was based on an open 2-compartment model. It has been proved that already 30 min after oral administration effective serum concentrations could be reached, which are maintained over about 24 h. An approximate value of 71% was obtained for the bioavailability of metoclopramide of Gastronerton retard capsules. The action achieved by the administration of 1 capsule Gastronerton retard per day can be considered equal to that of 3 single administrations of the conventional oral pharmaceutical form.

Administration, Oral↗
PubMed1983

The bacteriophage lambda terminase. Partial purification and preliminary characterization of properties.

The maturation of bacteriophage lambda DNA and its packaging into preformed heads to produce infectious phage is under the control of the two leftmost genes on the lambda chromosome, i.e., Nu1 and A. Based on its ability to complement lambda A- phage-infected cell extracts for packaging of lambda DNA in vitro, a single protein, designated terminase (ter) has been extensively purified using adsorption, ion exchange, and affinity column chromatography. The final preparation represents an approximately 60,000-fold purification over the activity found in crude extracts and is about 30 to 80% homogeneous as judged by visualizing the protein after electrophoresis in sodium dodecyl sulfate-polyacrylamide gel. In addition to packaging, terminase can also catalyze the endonucleolytic cleavage of lambda cohesive-end site DNA; both of these reactions require ATP. In some preparations, certain terminase fractions of extreme purity require protein factors present in extracts of uninfected Escherichia coli in order to catalyze the cohesive-end site cleavage reaction. On ion exchange columns purified terminase co-chromatographs with a DNA-dependent ATPase activity, hydrolyzing ATP to ADP and Pi in the presence of any of several types of DNA tested including those of non-lambda origin. The molecular weight of the native enzyme is 117,000 and appears to be a hetero-oligomer composed of 2 nonidentical subunits. The most likely composition of terminase is one gpA (gene product of A), Mr = 74,000 and two gpNu1, Mr = 21,000.

Adenosine Triphosphatases↗
PubMed1983

Periodontal status following the alignment of palatally impacted canine teeth.

Twenty-three patients who had completed treatment to resolve the unilateral palatal impaction of a maxillary canine by orthodontic means were examined 2.3 years (mean) after all appliances had been discarded. Scores were noted for the plaque index, gingival index, attached gingiva, pocket depth, and bone support on each of the affected teeth and also on the contralateral canine which had been unaffected and thus acted as a control. In addition, the teeth immediately adjacent to both canines were similarly scored. The results indicated no significant difference in the plaque index and the amount of attached gingiva, while the gingival index, pocket depth, and particularly the bone support all showed statistically valid differences. It is suggested that in these cases a postorthodontic assessment of the state of the supporting tissues be performed and periodontal treatment instituted in those requiring it.

Alveolar Process↗
PubMed1983

The effect of contrast media on the growth of bacteria.

Some water-soluble radiological contrast agents have been shown to have anti-bacterial activity, a phenomenon which might interfere with bacterial cultures from body fluids containing contrast media. The new low-osmolality contrast media are known to achieve much higher urinary concentrations than their predecessors in intravenous urography, and any anti-bacterial properties they might possess could be especially important in this examination. These agents have been examined with some conventional counterparts for anti-bacterial activity against a range of common pathogens with some positive results. Several parameters which might be thought to play a role in the phenomenon--osmolality, free iodide, pH and the methylglucamine radical--have been examined and eliminated. The bactericidal effect manifested by several contrast agents was found to be eliminated in the presence of urine, dispelling fears for urine cultures following urography, but a theoretical problem still remains in examinations of the biliary tract with some of the media.

Bacteria↗
PubMed1982

Bacteriophage lambda DNA packaging in vitro. The involvement of the lambda FI gene product, single-strand DNA, and a novel lambda-directed protein in the packaging reaction.

The FI gene product (gp) of bacteriophage lambda is required during phage head assembly in vivo. Mutations in this gene lead to an accumulation of immature concatemeric lambda DNA and of proheads that appear normal and are competent for DNA packaging in vitro. This phenotype can be taken as evidence of a failure to couple DNA and proheads for packaging/maturation. In contrast to the requirement for gpFI in vivo, the packaging of lambda DNA in vitro occurs efficiently in the complete absence of gpFI. However, if ssDNA is included at the outset of the in vitro packaging reaction, DNA packaging is blocked. This block to packaging is relieved by addition of gpFI. Thus packaging of lambda DNA in vitro can be made dependent of gpFI by the inclusion of ssDNA at the outset of the reaction. Inhibition of DNA packaging by ssDNA appears to be mediated by a lambda b region-directed protein (packaging inhibitor, ben protein) that is present in the crude extracts of cells used to support the early steps of the packaging reaction. Neither ssDNA nor the packaging inhibitor alone has significant inhibitory effect on packaging; both components are required together to effect the inhibition that is relieved by gpFI. The packaging inhibitor was extensively purified and shown to have endonucleolytic activity. Several lines of evidence are presented to support the idea that both the inhibitory and endonucleolytic activities are functions of the same protein. Although gpFI relieves the inhibition imposed by the ben protein in packaging, gpFI fails to block the DNA cleavage activity of the ben protein in the standard endonuclease assay.

Bacteriophage lambda↗
PubMed1982

A novel endonuclease specified by bacteriophage lambda. Purification and properties of the enzyme.

A DNA endonuclease whose expression is under the control of the b region of bacteriophage lambda has been partially purified from an induced lambda lysogen. In a reaction that requires single-stranded DNA, ATP, and Mg2+, the lambda-induced endonuclease makes one double strand break in pBR322 and other covalently closed circular DNA molecules, converting these substrates into unit-length linear forms. The double strand break in pBR322 DNA occurs at one of several preferred sites. Linear DNA appears not to be a good substrate for the enzyme.

Bacteriophage lambda↗