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Biomedical subjects

M MacMillan

Publications and source records attributed to M MacMillan.

29 records · Page 2Linked to original sources
PubMed1991

The effect of omental pedicle graft transfer on spinal microcirculation and laminectomy membrane formation.

The properties of the omentum and its effect on spinal neurologic disease was investigated. Omental pedicle grafts were transferred to the laminectomized lumbar spines of nine neurologically normal dogs. Grafts were placed on either the dura or the spinal cord. Interruption of the graft's circulation was examined. To study the effect, the artery of the graft was injected with contrast and the graft-dura interface studied histologically. All injected specimens demonstrated vascular connections from the graft to the neural elements. The graft was found to decrease postoperative perineural scarring. The omentum appears to possess properties that could be applied to improve outcomes in spinal surgery.

Animals↗
PubMed1990

Quantitative assessment of full range-of-motion isometric lumbar extension strength.

The purpose of this study was to evaluate the reliability and variability of repeated measurements of isometric (IM) lumbar extension (LB EXT) strength made at different joint angles. Fifty-six men (age, 29.4 +/- 10.7 years) and 80 women (age, 24.3 +/- 9.1 years) completed IM LB EXT strength tests on 3 separate days (D1, D2, and D3). On D1 and D2, subjects completed two tests (T1 and T2) separated by a 20- to 30-minute rest interval. For each test, IM LB EXT strength was measured at 72, 60, 48, 36, 24, 12, and 0 degrees of lumbar extension. Mean IM strength values, within-day reliability coefficients, and test variability over the seven angles improved from D1 to D2 (D1: mean, 160.0 to 304.1 N.m, r = 0.78 to 0.96, SEE = 37.6 to 46.9 N.m; D2: mean, 176.3 to 329.1 N.m, r = 0.94 to 0.98, SEE = 29.0 to 34.4 N.m). Mean strength values leveled off by D3 (174.5 to 317.0 N.m). The most reliable test results showed that the IM LB EXT strength curves were linear and descending from flexion to extension and ranged from 235.8 +/- 85.2 to 464.9 +/- 150.7 N.m for men (extension to flexion) and from 134.6 +/- 53.2 to 237.3 +/- 71.9 N.m for women. Lumbar extension strength was clearly greatest in full flexion, which is in contrast to previously reported results. One practice test was required to attain the most accurate and reliable results. These data indicate that repeated measures of IM LB EXT strength are highly reliable and can be used for the quantification of IM LB EXT strength through a range of motion.

Adult↗
PubMed1990

Transient neurologic deficits associated with thoracic and lumbar spine trauma without fracture or dislocation.

Two categories of persistent posttraumatic neurologic deficits of the spinal cord without evidence of a spinal fracture or dislocation have been described previously. Spinal cord injury without radiographic abnormality (SCI-WORA) is seen in children. In the elderly, hyperextension injuries causing neurologic deficits without bony injury have also been described. The purpose of this report is to review mechanisms by which transient neurologic deficits occur in the absence of bony disruption. The authors describe four cases in which transient neurologic deficits occurred after blunt trauma to the thoracic or lumbar spine. Their experience indicates that, when neurologic deficits after trauma occur without fracture or dislocation, there is often an underlying structural susceptibility of the axial skeleton.

Adolescent↗
PubMed1988

Effect of irrigation and tourniquet application on aminoglycoside antibiotic concentrations in bone.

Preoperative antibiotics are an important measure taken to prevent infection in joint replacement surgery. The local availability of these antibiotics in the operative site is absolutely necessary to ensure adequate prophylaxis against contaminant bacteria. Because pulsatile-lavage rapid-recovery systems have become a routine technique of bone preparation in joint reconstruction, we chose to study the effect of these systems on local antibiotic concentrations. We further investigated the effect of irrigation with and without use of a limb tourniquet. For our study, we obtained 23 bone specimens in 16 patients undergoing joint reconstruction (14) or amputation (2). The patients were classified into one of four groups based on whether a tourniquet was applied during the procedure and whether the bone specimens were irrigated. In addition, matched blood samples were obtained to establish that therapeutic serum levels were achieved. Nine patients contributed 13 bone specimens, which underwent vigorous irrigation in vitro. None of these specimens had detectable levels of antibiotics, regardless of whether a tourniquet was used. Seven patients yielded 10 bone specimens, which were not irrigated. Five of these seven patients had detectable levels of antibiotics. In addition, the specimens from limbs without tourniquets had levels that averaged 0.51 microgram/ml while those with tourniquets averaged below 0.2 microgram/ml. Therefore, the use of vigorous irrigation in bone preparation has a significant deleterious effect on the local presence of previously administered systemic antibiotics. This effect is compounded if the operative site is isolated from continuous blood flow by use of a tourniquet. We therefore recommend that additional measures be taken to ensure that adequate antibiotic levels are present.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

An experimental flexor tendon repair in zone II that allows immediate postoperative mobilization.

An experimental method of approximating severed flexor tendons in zone II that allows immediate postoperative mobilization is described. The repair uses a nonabsorbable suture anchored into the severed tendon in zone III. This experimental repair was performed on one foot in each of 18 adult, white Leghorn chickens. The control side used the modified Kessler technique to repair the zone II laceration. The animals were prevented from weight-bearing activities but were allowed active motion of the foot for 5 to 6 weeks postoperatively. The results demonstrated a marked diminution in flexor tendon adhesions, with intrinsic tendon collagen formation serving to reconstitute tendon continuity on the experimental side. The breaking strengths of the two repair methods were equivalent. These results suggest that this method may allow primary repair of tendon injuries in zone II, with minimal formation of adhesions.

Animals↗
PubMed1984

Free tyrosine levels of rat brain and tissues with sympathetic innervation following administration of L-tyrosine in the presence and absence of large neutral amino acids.

The tyrosine concentration of fasted rats was measured in plasma, brain and tissues receiving sympathetic innervation after L-tyrosine (200 mg/kg) was administered alone or in the presence of an equimolar cocktail containing isoleucine, leucine and valine. In the samples taken at 15, 30, 45, 60, 120 or 180 minutes, the highest concentrations of L-tyrosine were observed in plasma, heart, adrenal gland and kidney at 15 minutes, but in interscapular brown adipose tissue at 15 and 30 minutes and in brain at 15-60 minutes. The decline from peak concentrations was slower in brain, kidney and interscapular brown adipose tissue than in plasma, but in all tissues examined, control levels of free tyrosine were attained by 180 minutes postadministration . Competing large neutral amino acids reduced the maximal uptake of tyrosine in the brain by 48% but had no effect in the other tissues examined.

Adipose Tissue, Brown↗