Biomedical subjects

J B Boyd

Publications and source records attributed to J B Boyd.

At least 91 records · Page 5Linked to original sources

PubMed1986

Effect of steroids in maxillofacial surgery.

Thirty-six pediatric patients (age range, 6 to 18 years; mean, 15 years) undergoing mandibular and/or maxillary osteotomies were examined in a randomized double-blind study to determine objectively whether steroids are therapeutic in such operations. Dexamethasone or a saline placebo was administered immediately preoperatively (0.5 mg/kg) and for 48 hours postoperatively (0.25 mg/kg/day). Standardized surgical techniques and fluid administration were used. Photographs of the patient taken on admission and 24 hours postoperatively were compared by three independent observers familiar with maxillofacial surgery to rate facial swelling. Mean intubation period (until an audible leak around the endotracheal tube was present), time until oral intake was satisfactory, and facial swelling ratings were compared between the two groups. The results seemed better for the patients receiving steroids but the difference was not significant. This study did not confirm the subjective belief of many surgeons that steroid administration reduces facial swelling after maxillofacial surgery.

Adolescent↗

PubMed1986

Reduction mammaplasty: a comparison between the Robbins and Pontes techniques.

The purpose of this paper is to propose a practical classification of mammary hypertrophy and compare perioperative factors in two types of reduction mammaplasty: the Pontes and Robbins techniques. In a series of 51 patients, the advantages and disadvantages of each method are compared and discussed. The Pontes method appears to be better for the low-volume and ptotic (type II and III) breast, whereas the Robbins technique has a more universal application.

Breast↗

PubMed1985

Purification and characterization of a DNA polymerase beta from Drosophila*.

A DNA polymerase with properties similar to mammalian polymerase beta has been isolated to near homogeneity from embryos of Drosophila melanogaster. A combination of exclusion chromatography and sodium dodecyl sulfate-gel electrophoresis indicates that this enzyme is composed of a single polypeptide of molecular weight-110,000. Optimum activity on a nicked template occurs at pH 8.4 in the presence of 15 mM MgCl2 and 250 mM NaCl. Enzyme activity is strongly inhibited by dideoxythymidine triphosphate but is relatively insensitive to aphidicolin and N-ethylmalemide. These properties clearly distinguish this enzyme from polymerase alpha, which has previously been characterized from this tissue. This report represents the first extensive purification of a beta-like polymerase from the Protostomic branch of the animal phylogenetic tree. It furthermore generates the potential for a genetic analysis of the function of polymerase beta in DNA recombination, repair, and synthesis.

Animals↗

PubMed1985

The giant (gt) mutants of Drosophila melanogaster alter DNA metabolism.

Abnormalities in DNA metabolism have been found in third-instar females of Drosophila melanogaster that are heteroallelic or homoallelic for X-chromosomal giant (gt) mutations. Analysis of DNA metabolism in larval brain ganglia was carried out using alkaline sucrose gradient centrifugation, incorporation assays and a neutral filter elution assay. These analyses show that gt stocks synthesize DNA of a reduced molecular weight, have an unusually high frequency of spontaneous single and double-strand breaks, and exhibit a reduction in the normal inhibition of DNA synthesis following treatment with UV and the carcinogen AAAF. These phenomena are not associated with a defect in the repair of X-ray induced DNA breaks nor are they accompanied by any alterations in chromosome stability. Analysis of homozygous 1(2)gl larvae also reveal that these phenomena are specific to the gt locus and are thus not attributable solely to an extended developmental program. These findings strengthen the suggestion that the genetic instability associated with gt is related to perturbations in chromosome metabolism (Green 1982).

Acetoxyacetylaminofluorene↗

PubMed1984

The versatile deep inferior epigastric (inferior rectus abdominis) flap.

The deep inferior epigastric vascular system nourishes a vast area of the anterior abdominal wall and offers a versatile variety of tissue combinations to the reconstructive surgeon for local or free flap transfer. Its supply to and beyond the rectus abdominis muscle provides the basis for flap design. Eighteen cases are presented to illustrate various muscle, myocutaneous and myosubcutaneous flaps that have been used to date to repair defects in the extremities and in the head and neck. The ease of dissection, coupled with the large calibre and length of the vascular stem, are key factors which combine to offer a speedy and a reliable technique. The donor site scar has been improved by the use of a suprapubic transverse incision to dissect the pedicle and this exposure provides access to the iliac crest for bone grafts where indicated. Time will evaluate this technique and further designs and modifications will undoubtedly be forthcoming. Meanwhile the initial results have been most promising.

Abdominal Muscles↗

PubMed1984

Histologic patterns of congenital nevocytic nevi and implications for treatment.

The therapeutic problems associated with congenital nevocytic nevi (CNN) have lead to a flurry of interest in neonatal dermabrasion. This is based on the theory that nevus cells at birth are superficial and accessible to dermabrasion and that they later migrate into the deeper dermis. We studied twelve patients with CNN, including seven patients less than 3 months of age, with serial biopsies taken over a period of 15 months. In addition, four neonates with giant CNN underwent dermabrasion, and biopsies were obtained pre- and postoperatively. The histologic features of CNN and the implications for treatment are discussed. Our results are inconsistent with the idea of migration of nevus cells into the dermis during infancy. Dermabrasion of giant CNN at an early age may improve the cosmetic appearance; however, it will not remove most nevus cells and is not recommended as an effective treatment for the prevention of melanoma.

Adolescent↗

PubMed1984

The vascular territories of the superior epigastric and the deep inferior epigastric systems.

The vascular territories of the superior and the deep inferior epigastric arteries were investigated by dye injection, dissection, and barium radiographic studies. By these means it was established that the deep inferior epigastric artery was more significant than the superior epigastric artery in supplying the skin of the anterior abdominal wall. Segmental branches of the deep epigastric system pass upward and outward into the neurovascular plane of the lateral abdominal wall, where they anastomose with the terminal branches of the lower six intercostal arteries and the ascending branch of the deep circumflex iliac artery. The anastomoses consist of multiple narrow "choke" vessels. Similar connections are seen between the superior and the deep inferior epigastric arteries within the rectus abdominis muscle well above the level of the umbilicus. Many perforating arteries emerge through the anterior rectus sheath, but the highest concentration of major perforators is in the paraumbilical area. These vessels are terminal branches of the deep inferior epigastric artery. They feed into a subcutaneous vascular network that radiates from the umbilicus like the spokes of a wheel. Once again, choke connections exist with adjacent territories: inferiorly with the superficial inferior epigastric artery, inferolaterally with the superficial circumflex iliac artery, and superiorly with the superficial superior epigastric artery. The dominant connections, however, are superolaterally with the lateral cutaneous branches of the intercostal arteries. For breast reconstruction, it would appear that prior ligation of the deep inferior epigastric artery would be of advantage when elevating the lower abdominal skin on a superiorly based rectus abdominis musculocutaneous flap. The vascularity of this flap would be further increased by positioning some part of the skin paddle over the dense pack of large paraumbilical perforators. Based on these anatomic studies, the relative merits of the superior and deep inferior epigastric arteries with respect to local and distant tissue transfer using various elements of the abdominal wall are discussed in detail.

Abdominal Muscles↗

PubMed1984

Skeletal changes associated with vascular malformations.

Five hundred and eighty birthmarks were reviewed; 356 were hemangiomas and 224 were malformations. Bony alterations occurred in association with only 1 percent of hemangiomas, in contrast with 34 percent of patients with vascular malformations. These alterations in bone development were classified according to size, shape, and density changes. Hypertrophy and distortion were typical of lymphatic malformations. Hypoplasia and demineralization were characteristic findings in the extremity venous malformations. Destructive and intraosseous changes were more commonly noted in the arterial or high-flow lesions. Possible mechanisms of altered skeletal growth include mechanical, physiological, and developmental processes.

Adolescent↗

PubMed1984

The elderly patient and colon surgery for cancer or diverticular disease.

The mortality and morbidity for 246 patients over the age of 50 who underwent colon resection for cancer or diverticular disease during a 5-year period were reviewed. The increased risk for patients over 70 years of age was based on the presence of two or more preoperative diseases, the occurrence of emergency surgery and the occurrence of postoperative complications, especially surgical infection.

Age Factors↗

PubMed1984

Future of dental education: strategic issues.

Dental education institutions, as components of university systems, must develop short-, mid-, and long-range plans for program development, resource allocation, evaluation, and continued financial support. This ongoing process must be accomplished in a very competitive academic arena where program excellence and program relevance are key issues in the game of survival. This presentation has focused on the major issues raised by the Strategic Plan of the American Dental Association, which must be considered by education institutions as they develop their plans. The Strategic Plan outlines some of the most crucial issues in dental education, and careful study of its content should be an obligatory step in any dental school planning process.

Costs and Cost Analysis↗

PubMed1983

The extended deep inferior epigastric flap: a clinical technique.

A versatile flap based on the deep inferior epigastric artery is presented. Its application for local and free-flap transfer is discussed and presented in two clinical cases. The possible inclusion of bone as an osteocutaneous flap is outlined. The flap can be raised with ease and speed, and the donor site is repaired as a linear scar. Since the latissimus dorsi flap with its pedicle based in the axilla has become the workhorse for the upper torso, this extended flap may become its distal counterpart with its pedicle based on the groin.

Adolescent↗

PubMed1982

Repair of double-strand DNA breaks in Drosophila.

This study describes the repair kinetics of DNA double-strand breaks in primary and established cell cultures of Drosophila melanogaster. Double-strand breaks, induced by X-irradiation, were monitored by neutral elution. In primary cell cultures 50% of the double-strand breaks induced by 10 kR of X-rays are repaired within 45 min and 80% of the breaks are repaired within 2-3 h. Repair kinetics in established cell cultures are similar; 50% of the induced breaks are repaired within 20 min and 88% within 3 h. Mutants deficient in other types of DNA repair were also assayed for their capacity to repair double-strand breaks.

Animals↗

PubMed1982

Apurinic endonuclease from Drosophila melanogaster: reduced enzymatic activity in excision-deficient mutants of the mei-9 and mus(2)201 Loci.

An endonuclease activity, which is specific for partially depurinated PM2 DNA, has been assayed in extracts prepared from cultured cells and larval brain ganglia of Drosophila melanogaster. Activity detected in repair-proficient cells is stimulated by Mg++ and is inhibited by EDTA. Extracts prepared from established cell cultures of the excision-deficient strain mei-9a and from larval brain ganglia derived from y mei-9a, mei-9L1, sn3 mei-9D2 and sn3 mei-9D4 are partially deficient in this activity. At least one allele of a second excision-deficient strain, cn mus (2)201D1, also shows reduced AP-endonuclease activity in ganglia extracts.

Animals↗

PubMed1982

Postreplication repair defects in mutants of Drosophila melanogaster.

Mutants of Drosophila melanogaster which are defective in DNA synthesis have been identified among mutagen-sensitive stocks through analysis of both organ and cell cultures. A new procedure employing larval brain ganglia allows poorly fertile or sterile mutants to be analyzed for the first time. Parallel studies were performed in both tissues to establish the sensitivity of the new assay relative to that of the proven cell-culture assay. Damage was induced in the DNA of cultured cells with UV irradiation and in that of ganglial cells with the carcinogen N-acetoxy-2-acetylaminofluorene. Cultures were then pulse-labeled with 3H-thymidine, incubated in the absence of thymidine, and the newly synthesized DNA was analyzed by alkaline sucrose gradient centrifugation. The molecular weight of labeled DNA from mutant cells was compared with that from control cells to assess the effect of the mutant on DNA synthesis. Among 16 mutant stocks that were scanned in either or both tissues, seven show reductions in DNA synthesis using an undamaged template. Mutants at five different genetic loci [mus(2)205, mus(3)304, mus(3)308, mus(3)310 and mus(3)311] possess a reduced capacity to synthesize DNA on a UV-damaged template in primary cell cultures. Four of these five defects can also be detected in carcinogen-treated organ cultures. Two additional defects in postreplication repair were observed with the brain-ganglia assay in strains that cannot be assayed in cell culture [mus(1)108, mus(2)206].

Culture Techniques↗

PubMed1982

Identification of a second locus in Drosophila melanogaster required for excision repair.

The mus(2)201 locus in Drosophila is defined by two mutant alleles that render homozygous larvae hypersensitive to mutagens. Both alleles confer strong in vivo somatic sensitivity to treatment by methyl methanesulfonate, nitrogen mustard and ultraviolet radiation but only weak hypersensitivity to X-irradiation. Unlike the excision-defective mei-9 mutants identified in previous studies, the mus(2)201 mutants do not affect female fertility and do not appear to influence recombination proficiency or chromosome segregation in female meiocytes.--Three independent biochemical assays reveal that cell cultures derived from embryos homozygous for the mus(2)D1 allele are devoid of detectable excision repair. 1. Such cells quantitatively retain pyrimidine dimers in their DNA for 24 hr following UV exposure. 2. No measurable unscheduled DNA synthesis is induced in mutant cultures by UV treatment. 3. Single-strand DNA breaks, which are associated with normal excision repair after treatment with either UV or N-acetoxy-N-acetyl-2-aminofluorene, are much reduced in these cultures. Mutant cells possess a normal capacity for postreplication repair and the repair of single-strand breaks induced by X-rays.

Alleles↗

PubMed1982

A rapid and effective method of skin graft stabilization in burned children.

A rapid and effective method of securing multiple skin grafts to burned children is described. It entails stapling an elastic net over grafts that have been backed onto Sofratulle. The staples pierce normal or healed tissue on the periphery of the wound, thus avoiding hemorrhage. The two-way stretch of the net prevents shearing during movement yet facilitates access for adjustment and routine graft care. Skin grafts are held against their bed with firm, even pressure. This method is not only easier and more rapid than direct stapling methods but offers a better prospect of a complete take.

Bandages↗

PubMed1981

Postreplication repair-defective mutants of Drosophila melanogaster fall into two classes.

Primary cell cultures derived from embryos of a control stock of Drosophila melanogaster respond to ultraviolet light within the first hour after exposure with a decline in thymidine incorporation and a decline in the ability to form newly synthesized (nascent) DNA in long segments. Cells derived from two nonallelic excision-defective mutants (mei-9 and mus201) exhibit the same quantitative decline in both phenomena as do control cells. In contrast, cells from five nonallelic postreplication repair-defective mutants (mei-41, mus101, mus205, mus302 and mus310) respond to ultraviolet light by synthesizing nascent DNA in abnormally short segments. Two of these five mutants (mus302 and mus310) also exhibit unusually low thymidine incorporation levels after irradiation, whereas the other three mutants display the normal depression of incorporation. These results indicate that excision repair does not influence the amount or the length of nascent DNA synthesized in Drosophila cells within the first hour after exposure to ultraviolet light. Of the five mutations that diminish postreplication repair, only two reduce the ability of irradiated cells to synthesize normal amounts of DNA.

Animals↗

PubMed1981

Abnormal recovery of DNA replication in ultraviolet-irradiated cell cultures of Drosophila melanogaster which are defective in DNA repair.

Cell cultures prepared from embryos of a control stock of Drosophila melanogaster respond to ultraviolet light with a decline and subsequent recovery both of thymidine incorporation and in the ability to synthesize nascent DNA in long segments. Recovery of one or both capacities is absent or diminished in irradiated cells from ten nonallelic mutants that are defective in DNA repair and from four of five nonallelic mutagen-sensitive mutants that exhibit normal repair capabilities. Recovery of thymidine incorporation is not observed in nine of ten DNA repair-defective mutants. On the other hand, partial or complete recovery of incorporation is observed in all but one repair-proficient mutagen-sensitive mutant. Irradiated cells from two mutants that display no excision capacity exhibit a gradual arrest of thymidine incorporation within 20 h after the initial decline. This arrest of incorporation is not observed in mutants exhibiting only partial defects in excision repair. Recovery of the ability to synthesize nascent DNA in long segments is normal in cells from the two mutants that display no excision capacity, indicating that recovery does not depend upon the excision of pyrimidine dimers from cellular DNA. Recovery of that ability is not observed, however, in cells from one partially excision-defective mutant, two of three postreplication repair-defective mutants, two of four mutants defective in both excision and postreplication repair, and one of five repair-proficient mutagen-sensitive mutants. These results indicate that recovery of normal DNA replication in irradiated Drosophila cells depends upon the activity of several functions.

Animals↗