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Biomedical subjects

R E Allen

Publications and source records attributed to R E Allen.

At least 109 records · Page 6Linked to original sources
PubMed1978

Management of acute lower extremity arterial ischemia due to embolism and thrombosis.

Despite a general impression to the contrary, a recent survey showed that the current mortality rate for acute arterial ischemia approximates 25%. Much of this apparently relates to toxins and procoagulants released from the dying limb, a tendency which may be enhanced further by attempts at revascularization. Based on these observations, we have utilized selective management of acute arterial ischemia in an attempt to minimize deaths and to salvage the maximum number of limbs. If the patient presents within 6 to 8 hours of the onset of acute arterial occlusion and if paralysis or anesthesia is present, then ultimate limb loss is likely. The therapeutic choices are high-dose heparin therapy, operative removal of the clot, or amputation of the limb--the ultimate choice being dependent upon the particular status of the patient. But if sensation and motor function are present, viability of the limb is not threatened, and good results can be obtained by utilizing anticoagulation and delayed elective revascularization, if the latter is indicated. But revascularization attempts after 10 to 12 hours of severe ischemia often are unsuccessful, and ischemia is followed by either recurrent thrombosis and ultimate limb loss, or by death from the systemic effects of reperfusion of ischemic tissue. This type of limb is managed best by using high-dose heparin therapy if viable, or by amputation if it is not. Employing the above criteria, 54 patients with acute arterial ischemia averaging 59 years of age, were treated. Seventeen had immediate thrombectomy, yielding two deaths and four subsequent amputations. Twenty-nine received anticoagulation treatment, resulting in one death and five amputations, and six had immediate amputation, yielding one death. Three had no specific treatment, with one poor result. There were four deaths in the entire series--a mortality rate of 7.5%--and two thirds of the limbs were salvaged. We have concluded that selective management, as prescribed above, was responsible for a significant decrease in mortality rate with no corresponding increase in limb loss, and that high-dose heparin therapy ultimately may prove the initial treatment of choice in all cases of acute arterial ischemia.

Acute Disease↗
PubMed1976

Some properties of purified skeletal muscle alpha-actinin.

Highly purified alpha-actinin can be made by using the low ionic strength extraction procedure previously described (Arakawa N., Robson, R. M., and Goll, D. E. (1970) Biochim. Biophys. Acta 200, 284-295) and then subjecting the crude alpha-actinin fraction obtained with this extraction procedure to successive chromatography on DEAE-cellulose and hydroxyapatite. Hydrozyapatite chromatography specifically removes a protein having a subunit molecular weight of 42,000 on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Hydroxyapatite-purified alpha-actinin sediments entirely as a 6.21 S boundary in the analytical ultracentrifuge with no trace of the small 9 to 10 S boundary seen in earlier alpha-actinin preparations purified by DEAE-cellulose chromatography. In 100 mM KCl, 20 mM Tris-acetate, pH 7.5, hydroxyapatite-purified alpha-actinin has a diffusion coefficient (D020,w) of 2.71 X 10(-7) cm2-s-1, an intrinsic viscosity of 20.6 ml-g-1, a molecular weight of 201,000 +/- 4,300 (plus or minus least squares standard error) as determined by sedimentation equilibrium, and a molecular weight of 210,000 as determined by sedimentation diffusion. In 6 M guanidine HCl, hydroxyapatite-purified alpha-actinin has a molecular weight of 106,000 +/- 6,300 as determined by sedimentation equilibrium and a molecular weight of 100,000 as determined by a calibrated 4% agarose gel permeation column. SDS-polyacrylamide gel electrophoresis gives a molecular weight of 96,000 to 100,000 for hydroxyapatite-purified alpha-actinin. Rod-shaped particles 44 X 390 to 400 A are seen in electron micrographs of negatively stained alpha-actinin. By assuming 45% hydration and a molecular weight of 206,000, dimensions of approximately 40 X 500 A can be calculated for the alpha-actinin molecule by using either s 020, w, D 020, w, intrinsic viscosity, or a calibrated 6% agarose gel permeation column. Hydroxyapatite-purified alpha-actinin has an alpha-helical content of 74% as measured by circular dichroism at 208 nm.

Actinin↗
PubMed1976

Pancreatic tumor of mesenchymal origin presenting as obstructive jaundice.

A case of an unusual tumor occurring in the head of the pancreas is presented. Definitive diagnosis could not be made, the lesion being either a low grade myxofibrosarcoma or a benign fibrous histiocytoma. The literature is discussed and several cases believed to be pancreatic sarcomata are presented, only one of which was definitely of pancreatic origin. No other case of fibrous histiocytoma of the pancreas has been reported.

Adult↗