Biomedical subjects

B J Masterson

Publications and source records attributed to B J Masterson.

At least 37 records · Page 2Linked to original sources

PubMed1988

Locking mechanism strength of absorbable ligating devices.

The locking mechanism strengths of the absorbable Absolok and Lactomer ligating clips and the absorbable Lactomer staple have been determined following implantation in an animal model. Three sizes of each type of clip and the single size of staple were enclosed in open mesh nylon pouches and implanted subcutaneously in rabbits for periods of 4, 7, 14, 21, and 28 days before tensile testing of the lock mechanisms. No change in the lock mechanism strength was detected for the Absolok clips before 21 days. The Lactomer clips and staples, however, showed significant decrease in lock mechanism strength within 7 days of implantation, this loss increasing with longer implantation times. A proportion of all the devices were found to have dissolved to an extent that precluded testing at 21 and 28 days. The findings indicate that the lock mechanisms of absorbable ligating clips differ significantly in their short-term (30 days) durability.

Animals↗

PubMed1988

Tensile characteristics of PTFE sutures.

The tensile strength load to failure and knotting characteristics of the six gauges of a new PTFE suture have been studied. In its unstressed state, the suture comprises 50% by volume of air but this diminishes upon stretching so that its diameter appears to be very large and the tensile strength low. The low surface-surface friction necessitates fairly complex knotting regimens (3 = 1 = 3 = 2 or 3 = 1 = 3 = 3) to ensure stable knot configurations, i.e. failure of the loop before knot failure. However, the relatively simple 2 = 1 = 1 = 1 configuration was found to have an adequate tensile strength.

Microscopy, Electron, Scanning↗

PubMed1988

Tensile properties of suture materials.

The tensile properties of three new sutures, two non-absorbable and one absorbable material, have been evaluated and compared with those of polypropylene and nylon sutures. It was found that the five materials differed significantly in their tensile strengths and elastic/plastic deformation characteristics but displayed comparable elongations at failure. All sutures showed a decrease in failure load and elongation at failure when knotted. Most materials showed an increased tensile strength and decreased elongation at failure for smaller suture gauges, and this behaviour is thought to be related to their internal molecular organization.

Biocompatible Materials↗

PubMed1988

Characterization of surgical needles.

The acuity (sharpness) of surgical needle points was assessed by measuring the force required for repeat needle penetrations through a medium-gauge latex sheet glued to a perforated Plexiglas frame. The data on the variation in the applied force with repeat penetrations showed that needles obeyed the general relation: P = A + B.n; where P is the applied penetration force in grams, n is the number of penetrations and A and B are constants. Constant A characterized the needle-point acuity and B the maintenance of acuity. This relationship indicated both needle acuity and acuity maintenance with repeated passes through a reproducible target material. Determining the microhardness of needles provided data on their strength which helped to account for differences in the acuity of apparently similar needles. The tensile strength of the union between suture and needle was determined to evaluate the security of suture attachment.

Latex↗

PubMed1988

Oral contraceptive agents: current status.

Oral contraceptives are the most widely prescribed and ingested drug in human history. The difficulty in establishing their clear-cut side effects is compounded by the rarity of these side effects and their occurrence with multiple other factors and cofactors that may be etiologically more important. For the prudent surgeon, suffice it to say that should operation require bedrest postoperatively, oral contraceptives should be stopped at least 2 weeks preoperatively and barrier methods begun. Barrier methods should also be used when drugs that interfere with oral contraceptives are prescribed. Oral contraceptives and anticoagulants should not be given together because of the chemical changes in the blood caused by the steroid content of the contraceptive. As surgeons, we must remember the contraindications noted herein and become familiar with the current literature as new developments unfold in the dynamic field of conception control.

Contraceptives, Oral↗

PubMed1988

Skin preparation.

Preoperative skin preparation, whether it is the patient's or the surgeon's, should be a brief event. Successful wound healing is determined more by what is done in the wound than what is done on the wound. More than $1 billion annually is wasted on prolonged skin preparation that is not useful to the patient.

Disinfection↗

PubMed1988

Effects of bacterial infection on absorbable vascular ligating clips.

Electron microscopic observations of two implanted absorbable clips, Absolok and Lactomer, infected with Escherichia coli and Streptococcus faecalis, were carried out. An overgrowth of bacteria was observed over the entire surface of the clips. The mating surfaces of the Lactomer clips and the locking mechanisms of both types of clip were more heavily infected--that is, provided better support for bacterial growth--than other areas of the clips in the initial postimplantation period. However, with longer periods (up to seven days), the initial bacterial deposits developed into a thick, plaquelike layer. This layer appeared to restrict access to the surfaces such that the infected clips degraded at a much slower rate than did the noninfected clips, particularly Lactomer clips, on which little morphologic change was detectable seven days after implantation.

Animals↗

PubMed1988

Tissue reactions to absorbable ligating clips.

Scanning electron microscopy was used in a comparative ultrastructural study of biodegradable ligating clips, the Absolok (polydioxanone) and the Lactomer (copolymer of glycolic and lactic acids), implanted subcutaneously in rabbits. The inflammatory response and tissue reactions to the implanted clips and their effects on clip breakdown were studied. By the first week after implantation, numerous inflammatory cells adhered to the clip surfaces, with occasional fibroblasts present. By two weeks after implantation there was a reduction in the number of inflammatory cells, but the number of fibroblasts gradually increased, resulting in encapsulation of the clips. The thickness of the fibrous tissue capsule, formed by a variety of collagen fibers, gradually increased 5-25 weeks after implantation. Residues from the Lactomer clips were still present within the encapsulating tissue at 25 weeks. In contrast, clips enclosed in nylon pouches were totally degraded, and no residues were detectable at 25 weeks. Tissue reactions similar to those observed for nonpouched implanted clips were seen over the entire external surface of the pouches.

Animals↗

PubMed1987

The use of nylon pouches to prevent cellular attachment to implanted materials.

A nylon pouch system has been developed to permit the in vivo exposure of implantable materials to tissue fluids without complications arising from cellular attachment or from the bacterial attack. SEM observations have indicated that the pouches were effective in reducing the ingress of bacteria as well as reducing, and in some cases eliminating, cell infiltration through their mesh structure. Over a 7 d implantation period, the exterior surfaces of the nylon pouches were heavily infested with microorganisms but there was minimal growth of bacteria within the pouches. Non-infected pouches that were implanted for up to 25 wk showed heavy deposits of cellular matter on the external surfaces of the pouches and minimal deposits within the pouches.

Absorption↗

PubMed1986

Mechanical properties of coated absorbable multifilament suture materials.

The mechanical properties of coated polyglactin 910 (Vicryl) and coated plyglycolic acid (Dexon) were defined. Scanning electron microscopy of 0 gauges of both materials showed some differences. Coated polyglycolic acid had minimal surface aberrations. Unknotted tensile strength measurements of gauges 1, 0, 00, and 000 demonstrated no statistically significant difference between the two materials. Both materials reached knot security at the 2=1=1=1 configuration. The in vivo tensile strength measurement of 0 gauges showed polyglactin 910 to be significantly stronger at 21 days. Histologic evaluation revealed no statistically significant difference between the materials.

Animals↗

PubMed1986

The biomechanical effects of tight suture closure upon fascia.

The biomechanical effect of tight suture closure of fascial incisions in male rats was evaluated. The incision of rats in group 1 was closed with maximum tension on the first throw of the approximating knot. The incision of rats in group 2 was closed in a similar manner, however a 3.14 squared millimeter rod was placed in the suture loop before securing the first throw. The rod was removed after the knot was formed and fascial edges were observed to be loosely approximated. All rats were sacrificed after seven days. The abdominal fascial and muscle unit was dissected and a 1 by 6 centimeter strip containing two suture loops was excised. Scanning electron microscopic examination of tissue specimens, tensile strength measurements and energy-to-failure under tensile loading studies were performed. Specimens for hydroxyproline assay were obtained from the tissue immediately surrounding the incision and between two suture loops. The scanning electron microphotographs of group 1 showed tissue overlap from the excessive force on the initial knot throws. Wounds loosely approximated had proper alignment of the wound edges and had greater proliferative activity in the clefts of the wounds. The tensile strength and energy-to-failure studies showed loosely approximated wounds to be far stronger (p less than 0.001). No statistically significant difference (p greater than 0.05) was found between hydroxyproline assays of the two groups.

Animals↗

PubMed1986

Establishment of a clinical teaching associates breast examination program for medical students.

A program was designed to instruct medical students on how to obtain a history pertinent to breast abnormalities and to perform a breast examination. The use of clinical teaching associates provides direct student instruction and critiques during the examination. In addition, students are taught how to instruct patients in the breast self-examination and to properly document breast abnormalities. Such a program should be considered for incorporation in all physical diagnosis courses as well as in residency training programs and seminars for practicing physicians.

Breast↗

PubMed1986

Perimenopausal bleeding.

The principal means of evaluating perimenopausal bleeding is endometrial biopsy performed in the office. With the rising incidence of endometrial cancer, an accurate diagnosis is imperative. Outpatient endometrial biopsy is well accepted by patients, provides ample tissue for histologic examination and has good diagnostic reliability. The increased use of estrogen in postmenopausal women and the importance of cost containment make this approach even more important.

Adult↗

PubMed1985

A comparative study of suture materials: chromic gut and chromic gut treated with glycerin.

Histologic and mechanical properties of chromic gut and glycerin-treated chromic gut were evaluated. Zero gauges of both materials were implanted for 7 days to evaluate inflammatory response. No difference was found in the degree of inflammatory response. Scanning electron micrographs showed a more uniform surface for the glycerin-treated chromic gut. Regular chromic material was stronger in unknotted tensile strength and fracture load for all gauges. The 1-0 gauge glycerin-treated chromic gut stabilized with the knot configuration of 1 = 1 = 1 = 1; and the 1,2-0, and 3-0 gauges reached knot security at 1 = 1 = 1. The in vivo studies showed marked difference in the tensile strength of stable knots between the two materials. Only with five throws (1 = 1 = 1 = 1 = 1) did the strength of glycerin-treated chromic gut overlap that of regular chromic gut.

Animals↗

PubMed1985

Cyclophosphamide and cisplatinum combination chemotherapy for the treatment of epithelial ovarian carcinoma.

A review of 18 patients with Stage III epithelial ovarian carcinoma treated by surgery and followed by cyclophosphamide and cisplatinum combination chemotherapy is presented. At the end of 12 months from the initiation of chemotherapy, 88.9% of the patients were alive and 77.8% remained free of tumor progression. At the end of 2 years 77.8% of the patients were alive and 44.4% of the patients were free of tumor progression. The combination of cyclophosphamide and cisplatinum has low toxicity, a simple pattern of administration, and has provided satisfactory results.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1985

Hexamethylmelamine, methotrexate and 5-fluorouracil (HMF) for progressive ovarian carcinoma during therapy with cis-platinum, cyclophosphamide +/- doxorubicin.

Hexamethylmelamine, methotrexate, and 5-fluorouracil (HMF) is a second-line chemotherapy for patients with ovarian carcinoma refractory to platinum-based regimens. Two of 15 patients with tumor progression treated with HMF alone had objective complete responses while one had a 12-month disease-free interval (DFI). Among 8 patients treated with HMF and either intraperitoneal chromic phosphate and/or alternating platinum-based chemotherapy following second-look surgery which documented persistent carcinoma, 3 have experienced disease-free intervals of 19, 27, and 42 months. However, no one has been cured or had a long-term remission after HMF therapy alone.

Adult↗

PubMed1985

Nutritional assessment in gynecology patients.

A nutritional assessment was performed upon 72 patients admitted for major elective gynecologic surgery for nonmalignant diseases. This nutritional assessment included body weight, triceps skinfold, arm muscle circumference, creatinine-height index, serum albumin and transferrin, total lymphocyte count, and dermal antigen testing. We found that 29 patients (42%) had at least one test result indicating a nutritional deficiency. Of the 72 patients, 19 (26%) experienced a postoperative complication. The occurrence of a complication did not correlate with any nutritional parameter other than albumin (p = 0.013), but even then, the positive predictive value of albumin was only 40%. Age also correlated with complication status (p = 0.002).

Body Height↗

PubMed1985

Comparison of clinical and surgical-staging in patients with endometrial carcinoma.

The preoperative clinical and radiologic findings and staging were compared with the operative and pathological findings and surgical staging in 62 consecutive patients with endometrial carcinoma. Overall, the tumor grade was changed in 33.8% of the patients, and the histologic type of tumor was changed in 27.4% of the patients. The preoperative clinical staging was changed in 51% of the patients after surgery. The change for the stage was as follows: stage I, 30.4%; stage II, 62.5%, stage III, 60%; and stage IV, 0%. The endocervical curettage was found to have a 50% false-positive rate and a 13% false-negative rate.

Dilatation and Curettage↗