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Biomedical subjects

M McCarty

Publications and source records attributed to M McCarty.

At least 37 records · Page 2Linked to original sources
PubMed1995

Group A streptococcus-liposome ELISA antibody titers to group A polysaccharide and opsonophagocytic capabilities of the antibodies.

Antibodies reactive with group A streptococci (GAS) carbohydrate were studied by ELISA and in an indirect bactericidal assay. The ELISA used GAS carbohydrate covalently bound to phosphatidylethanolamine incorporated into liposomes so that both precipitating and nonprecipitating antibodies were measured. Sera from children from different geographic areas exhibited marked differences in levels of anti-GAS carbohydrate antibody, which increased with age. The antibodies were predominantly of IgG. In bactericidal assays, most of these sera promoted phagocytosis of several type-specific M-positive strains. Opsonization was also related to serum levels of anti-GAS carbohydrate antibodies. These opsonizing antibodies were depleted from the serum by absorption of the sera on an N-acetyl-D-glucosamine affinity column. Antibody eluted from this column could partially restore opsonization of GAS. Anti-GAS carbohydrate antibodies play a major role in these opsonophagocytosis assays.

Antibodies, Bacterial↗
PubMed1995

Comparative biomechanical stability of titanium bone fixation systems in metacarpal fractures.

The biomechanical properties of apex bending and torsional rigidity of 11 different titanium mini- and microplates (Leibinger and Synthes) were examined to evaluate the effects of plate design and thickness and screw size and design. Two hundred sixteen fresh-frozen human cadaveric metacarpal bones underwent a midshaft transverse osteotomy followed by application of one of the following plates: Synthes 1.5-mm and 2.0-mm five-hole linear plates; Leibinger linear 1.2-mm 5-hole, 1.7-mm 4-hole, 2.3-mm 4-hole plates; or Leibinger three-dimensional 1.2-mm 4-hole, 1.2-mm 8-hole, 1.7-mm 4-hole, 1.7-mm 8-hole, 2.3-mm 4-hole, and 2.3-mm 8-hole plates. The specimens were subjected to a three-point bending test with apex dorsal or apex volar loading or torsional loading. Analysis of variance statistical analysis revealed that increasing plate thickness and, more significantly, three-dimensional design were associated with increased rigidity.

Biomechanical Phenomena↗
PubMed1995

Small intestinal submucosa: utilization for repair of rodent abdominal wall defects.

Prosthetic graft material is often used for the repair of abdominal wall defects that result from trauma, infection, neoplastic, or congenital deformities. A new material, porcine small intestinal submucosa, has been successfully used as an arterial and venous graft material in both canine and primate animal models with graft patency and infection rates equal to autologous vein. On the basis of these studies, small intestinal submucosa was used as a graft material for the repair of a 2 x 2-cm full-thickness defect of the muscle and fascia in the rodent abdominal wall (N = 11). Two animals were euthanized at 1 week, 2 weeks, 4 weeks, 2 months, and 3 months. At the time of euthanization, no abdominal hernias were noted and only minimal intra-abdominal adhesions were observed. One animal died on postoperative day 5 as a result of a wound dehiscence. Histological analysis of the excised abdominal wall hernia repairs revealed moderate initial inflammation but with incorporation of small intestinal submucosa with minimal inflammation at 2 months. No evidence of graft-versus-host rejection was noted with hematoxylin and eosin stains and light microscopy. Porcine small intestinal submucosa merits further study as a graft material for abdominal wall replacement.

Abdominal Muscles↗
PubMed1995

Small intestinal submucosa: utilization as a wound dressing in full-thickness rodent wounds.

Wound dressings are used as a temporary wound covering to promote wound healing, control wound exudate, and decrease wound contamination as well as evaporative water loss. A new material, porcine small intestinal submucosa, has been used successfully as an arterial and venous graft in both canine and primate animal models with graft patency and infection rates equal to autologous vein. Based on these studies, small intestinal submucosa was used as a biological wound dressing in 20 x 20 mm full-thickness wounds made on Sprague-Dawley rats. In the controls (group I, n = 12), an acrylic frame (20 x 20 mm) was sutured to the wound edges, followed by placement of a thin polyurethane film. In the small intestinal submucosa-treated animals (group II, n = 12), the wound was covered with small intestinal submucosa and then with the acrylic frame and polyurethane film. The wounds were examined both visually and histologically at postapplication days 3, 7, 14, 28, 42 and 56. In addition, the wound contraction rate of 6 animals in both groups were recorded at postapplication day 0 and then at 1 week, 1 month, 2 months, and 3 months. Histological analysis (hematoxylin-eosin and periodic acid-Schiff stains) of the small intestinal submucosa-treated wounds revealed no host-versus-graft rejection and a rate of epithelialization equal to that of the control group. The wound contraction rate was statistically significant (higher; p < .05) in the control group compared to the small intestinal submucosa-treated group. Porcine small intestinal submucosa merits further study as both a biological wound dressing and as a substrate for cultured cells.

Animals↗
PubMed1994

Experimental evaluation of small intestinal submucosa as a microvascular graft material.

The evaluation of porcine small intestine submucosa (SIS) in a microsurgical model was conducted using an interpositional graft in the rat femoral artery. The SIS grafts were fabricated from processed porcine material that was wrapped around a glass tube and oversewn longitudinally to produce a tubular structure. Of the 42 animals studied, 7 received grafts of untreated SIS (group I), 7 of the grafts were presoaked (PSH) in heparin (Group II), 7 animals were treated with systemic heparin prior to implantation of PSH-SIS (group III), 7 animals received SIS grafts crosslinked to heparin (group IV), 7 animals received SIS grafts crosslinked to urokinase (group V), and 7 animals received untreated autologous epigastric vein grafts (group VI). Patency was assessed postoperatively and selected grafts were evaluated by histology. All SIS grafts failed to maintain patency beyond the first postoperative hour. Histologic examination of the thrombosed graft surfaces revealed a smooth luminal surface with a thick layer of attached fibrin and platelets with a central occluding thrombus. The thickness of the induced fibrin layer appears to narrow intraluminal space significantly at the microvascular level. While having excellent success at vessel diameters greater than 3 mm, and in a variety of nonporcine animal models without xenographic rejection, SIS in this model was thrombogenic despite a favorable surface morphology as demonstrated by SEM. Even with use of heparin and urokinase SIS graft thrombosis occurred.

Animals↗
PubMed1994

Mechanical anastomosis of nerves: a histological and functional comparison to conventional suturing.

The use of a mechanical coupling device in microsurgery offers speed of application in addition to a secure vascular union. Despite its success in a vascular setting, mechanical coupling device nerve repair remains to be studied. Forty-five male rats were tested over 7- and 14-week study periods. One half of the animals underwent primary suture repairs for transected sciatic nerves, and the remainder of the animals had their nerves repaired using a mechanical coupling device. Postoperative analysis consisted of histological evaluation of pre- and postrepair site nerve morphology (axonal continuity and counts) as well as functional testing using walking track analysis. Mechanical coupling device coaptation of the nerves using the epineurium was done in approximately one half the time compared with conventional suturing. After both 7 and 14 weeks postoperatively, walking track analysis showed no difference in the amount of functional return between the two repair groups. No animal exhibited complete return of function. Axonal continuity occurred across both repairs without significant difference in their pre- and postrepair axonal counts. Although no clear advantage was seen in this study, the concept of mechanical nerve coupling merits further investigation based on its potential clinical utility.

Anastomosis, Surgical↗
PubMed1993

In Mls-1a mice, fetal-type beta-gene rearrangements are frequent among self-anergic V beta 6 T cells.

T lymphocytes generated in the fetal and neonatal period are characterized by T cell receptor (TCR) gene rearrangements that lack N region nucleotides (fetal-type TCR). Using fetal-type TCR as a lineage marker, we show that such T cells are long-lived and persist in the periphery of adult mice. Moreover, in both neonatal and adult environments, upon encounter with self-antigens, they are less likely to be deleted. Inefficient clonal deletion could be due to the intrinsic properties of the T cells generated during this period, or to yet unknown properties of the perinatal thymus. Such anergic T cells constitute a subset that can further expand in vivo in an antigen-independent fashion, leaving open the possibility for self-aggression under the appropriate triggering conditions.

Animals↗
PubMed1993

Surgical clip artefact mimicking arterial stenosis: a problem with magnetic resonance angiography.

In three patients undergoing three-dimensional phase contrast magnetic resonance angiography (MRA) for evaluation of renal transplant arteries, a convincing stenosis was demonstrated that was not present on conventional angiograms. In each patient there was a stainless steel surgical clip in the soft tissues adjacent to the renal artery. Although the clip artefact was easily recognized on the acquired tomographic magnetic resonance slices, it was completely indistinguishable from a true stenosis on the final projection images. This may limit the use of MRA in post-surgical vascular evaluation unless review is made of the phase contrast images.

Adult↗
PubMed1993

Ultrasound findings in hepatic mycobacterial infections in patients with acquired immune deficiency syndrome (AIDS).

Ultrasound findings in 12 AIDS patients with abdominal mycobacterial infections were reviewed and correlated with liver histology. Liver ultrasound abnormalities were common--present in 4/5 patients with Mycobacterium avium-intracellulare (MAI) and 7/7 patients with Mycobacterium tuberculosis (MTB) infection. The commonest ultrasound abnormality of the liver was a generally 'bright' liver, seen in 7/12 patients. Focal liver lesions were seen in 5/7 patients with MTB but were not seen in any patients with MAI infection. Both hyperechoic (two patients) and hypoechoic (three patients) lesions were seen. Lymphadenopathy as demonstrated on abdominal ultrasound was a relatively infrequent finding--only seen in three patients with MTB, all of whom also had focal liver lesions. On histology, 8/12 patients showed fatty infiltration and 8/12 showed granuloma. Abnormalities are commonly seen on ultrasound examination of the liver in AIDS patients with abdominal mycobacterial infections but are non-specific and ultrasound guided biopsy is indicated to confirm the diagnosis and exclude other disease.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Pneumothorax in patients with AIDS.

Eighty-seven inpatients were treated for 93 episodes of Pneumocystis carinii at St Mary's Hospital between January 1989 and December 1990. During this period, 298 patients with the acquired immunodeficiency syndrome (AIDS) were treated at this hospital. Sixteen episodes of pneumothorax occurred and 12 of these, occurring in ten patients, were unrelated to procedure. In six of 12 (50%), the pneumothoraces occurred concurrently with Pneumocystis carinii pneumonia (PCP) and in ten (83%) cases there was a past history of PCP. Bilateral pneumothorax occurred in five cases (42%). In seven (58%) of the cases, patients had been using aerosolized pentamidine as prophylaxis for PCP. This retrospective study confirms the association of pneumothorax with current PCP and also shows an association with previous infection. The use of aerosolized pentamidine was not associated with pneumothorax development. It is important to suspect pneumothorax in a patient with PCP who deteriorates acutely. The high incidence of bilateral pneumothorax means that pleurodesis should be considered early.

AIDS-Related Opportunistic Infections↗
PubMed1993

Effects of skeletal fixation on craniofacial imaging.

The imaging effects of high-density scatter from different metal compositions of plate and screw fixation systems were assessed in cadaveric craniomaxillofacial skeletons with computed tomographic scanning. Differences in image clarity of three-dimensional reconstructions were observed between titanium, stainless steel, and cobalt-chromium-molybdenum alloy onlay fixation systems, which were not significantly altered with or without an overlying soft-tissue density (facial drape). These differences were reduced in a plaster model, in which the plates were in an intrabony location.

Artifacts↗
PubMed1992

Case report: disseminated Pneumocystis carinii infection in a patient with the acquired immune deficiency syndrome causing thyroid gland calcification and hypothyroidism.

We present the case of a homosexual male patient with the acquired immune deficiency syndrome (AIDS) who developed disseminated infection with Pneumocystis carinii. He presented with symptoms and signs of thyroid disease, and developed thyroid gland calcification. This was later histologically proven to be due to P. carinii infection. Disseminated P. carinii infection is rare, and this case represents the first report to our knowledge of thyroid gland involvement causing both hypothyroidism and calcification.

Acquired Immunodeficiency Syndrome↗