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Biomedical subjects

G Beauregard

Publications and source records attributed to G Beauregard.

48 records · Page 3Linked to original sources
PubMed1980

Femoral head defect following anterior hip dislocation.

Impaction fractures of the femoral head following anterior hip dislocation were noted in eight of 11 patients. This fracture is characterized by a depression or a flattening of the posterosuperior and lateral portion of the femoral head. It is usually seen on the standard anteroposterior view of the pelvis.

Femur Head↗
PubMed1979

Neuraminidase activity in the mucolipidoses (types I, II and III) and the cherry-red spot myoclonus syndrome.

Two neuraminidase (EC 3.2.1.18) comonents, A and B, were distinguished in cultured skin fibroblasts on the basis of thermolability at 37 degrees C. The more labile component (A) t1/2 = 4.7--5.3 min at 37 degrees C, comprises 66--90% of total neuraminidase activity when determined using sodium (4-methylumbelliferyl-alpha-D-N-acetylneuraminate) (MU-alpha-N) as substrate. Activity was assayed at 0 degrees C for 18 h instead of 37 degrees C to fully determine both thermolabile and thermostable components. Diminished activity was noted in cultured fibroblasts from mucolipidoses I, II and III (MLI, MLII, MLIII) and the cherry-red spot myoclonus syndrome (CRSM) patients when assayed at both 0 and 37 degrees C with either MU-alpha-N or each of a series alpha (2 leads to 3)- and alpha (2 leads to 6)-linked N-acetylneuraminyloligosaccharides. Increased sensitivity and rapidity of analyses were achieved using MJ-alpha-N as substrate in determining neuraminidase activity. Results from two obligate heterozygote MLI cell lines (14.5 and 8.0% of control activity) indicate that the MU-alpha-N substrate could be useful for heterozygote detection.

Cells, Cultured↗
PubMed1979

Involvement of calcium ions in the properties of cardiolipin-associated erythrocyte acetylcholinesterase.

Lipoprotein forms of acetylcholinesterase from bovine erythrocytes gave non-linear Arrhenius plots with a break at 20 degrees C and contained cardiolipin. The break in the Arrhenius plot was abolished by incubation of the enzyme in high salt (I = 1.8), but only in Ca2+ -chelating conditions. At I = 1.8 neither NaCl alone, CaCl2 nor sodium phosphate at acidic pH abolished the break. However, at this ionic strength either NaCl in 2 mM sodium phosphate (pH 7.4) or sodium phosphate, pH 8, or 1.0 M Na2CO3/NaHCO3 (pH 8.5--10, were able to remove the break. The Arrhenius plot break was regenerated by the addition of Ca2+ to the high salt-treated enzyme with mild homogenization, but could not be regenerated in the presence of EDTA unless CaCl2 was added in excess of the EDTA. Conditions which abolished the break enabled endogenous cardiolipin to be removed from the enzyme by chloroform/methanol extraction Cardiolipin from acetylcholinesterase incubated in high salt in Ca2+ -chelating conditions was not accessible to digestion by phospholipase A2, and was not separated from the enzyme by flotation in a sucrose density gradient or by Sephadex G-200 chromatography. Thus both Ca2+ and cardiolipin appear to be inaccessible, possibly by being tightly associated in the hydrophobic core of the enzyme by ionic and hydrophobic forces. Ca2+ may modulate the temperature dependence of acetylcholinesterase activity through a functionally linked ionic interaction with the enzyme-cardiolipin complex.

Acetylcholinesterase↗
PubMed1979

Characterization of lipid-protein interactions in acetylcholinesterase lipoprotein extracted from bovine erythrocytes.

Acetylcholinesterase was released from bovine erythrocytes in hypo-osmotic sodium phosphate buffer. Initially, about 30% of the enzyme was released in a soluble lipoprotein form, and further incubation resulted in the progressive release of the enzyme in a particulate form. Solubilization of the acetylcholinesterase in the particulate fraction with Lubrol WX (2 mg/ml) resulted in the loss of all lipids except a non-exchangeable fraction identified as cardiolipin. Addition of a mixture of erythrocyte phospholipids to the soluble forms and to the Lubrol WX-solubilized enzyme resulted in the formation of particulate forms of the enzyme with increased partial specific volume and Stokes radius, and a break in the Arrhenius plot of the enzyme activity around 20 degrees C. The break in the Arrhenius plot was abolished by treatment of a soluble enzyme preparation with 1.8 M salt (NaCl) in phosphate buffer, conditions that allowed the extraction of cardiolipin from the enzyme by chloroform/methanol. Failure of the high-salt treatment to decrease the Stokes radius made it unlikely that the bound cardiolipin formed a boundary layer or annulus around the protein. It is suggested that cardiolipin is bound to the core of the dimeric protein structure, thereby controlling the acetylcholinesterase activity.

Acetylcholinesterase↗
PubMed1976

The right pleuromediastinal reflection in children.

The authors review the anatomy of the pleural reflection of the right lung against the middle mediastinum in childhood. In 505 consecutive normal frontal radiographs of children, from birth to sixteen years, this pleural reflection (also known as the pleuro-esophageal line) was visible in 83%. The entire reflection from thoracic inlet to diaphragm was clearly seen in 13%, chiefly in upright, deep-inspiration, well penetrated radiographs. It is a radiographic landmark in the middle mediastinum, particularly well seen in childhood, and its use in assessment of mass lesions, cardiomegaly and lung collapse is described.

Adolescent↗
PubMedDate not supplied

Surgical treatment of lumbosacral instability caused by discospondylitis in four dogs.

OBJECTIVE: To describe a surgical technique involving distraction and stabilization of the lumbo-sacral vertebral segment using an external skeletal fixator in dogs with lumbosacral instability caused by discospondylitis. STUDY DESIGN: Retrospective clinical study. ANIMALS: Four client-owned dogs. METHODS: Medical records of all dogs diagnosed with discospondylitis from 1994 to 1997 were identified and reviewed. Four dogs with lumbosacral discospondylitis requiring surgical treatment were then specifically studied. Surgical technique, clinical signs, preoperative diagnostic investigation, radiographic findings, and the results of short-term and long-term reevaluations were recorded. RESULTS: Twelve dogs with discospondylitis were identified, 4 of which had lumbosacral discospondylitis. These 4 dogs underwent surgical distraction and stabilization because they failed to respond to medical treatment. Three dogs received a cancellous bone graft between L7 and S1 and had rapid interbody fusion of this vertebral segment. The dog that did not receive a graft did not have interbody fusion at the time of fixator removal. This did not affect the final clinical outcome. Lumbosacral pain and neurological deficits present before surgery rapidly subsided after the procedure. All dogs received concurrent antibiotic treatment for a minimum of 4 weeks. All dogs were clinically normal at the time of fixator removal and all continued to do well during the follow-up period (8-48 months; mean, 27.5 months). CONCLUSION AND CLINICAL RELEVANCE: Lumbosacral discospondylitis may not respond well to conservative treatment because of the mobility of the affected space. Surgical treatment involving distraction and stabilization to obtain intervertebral fusion is very effective in treating lumbosacral instability caused by discospondylitis.

Animals↗