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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 1,495 records · Page 83Linked to original sources
PubMed1978

Malignant lymphomas. A cytological/histological classification.

Early diagnosis and differentiation of malignant lymphomas is important as the various types have a very different prognosis. Aspiration cytology is useful in the initial diagnosis, monitoring the change from one cell type to a more primitive cell type and for diagnosing spread of lymphoma.

Classification↗
PubMed1977

Non-covalent cross-linking of lipid bilayers by myelin basic protein: a possible role in myelin formation.

Myelin basic protein associates with bilayer vesicles of pure egg phosphatidylcholine, L-alpha-dimyristoyl phosphatidylcholine and DL-alpha-dipalmitoyl phosphatidylcholine. Under optimum conditions the vesicles contain 15-18% of protein by weight. The binding to dipalmitoyl phosphatidylcholine is facilitated above its gel-to-liquid crystalline transition temperature. At low ionic strength the protein provokes a large increase in vesicle size and aggregation of these enlarged vesicles. Above a sodium chloride concentration of 0.07 M vesicle fusion is far less marked but aggregation persists. The pH- and ionic strength-dependence of this aggregation follows that of the protein alone; in both cases it occurs despite appreciable electrostatic repulsion between the associated species. A similar interaction was observed with diacyl phosphatidylserine vesicles. These observations, which contrast with earlier reports in the literature of a lack of binding of basic protein to phosphatidylcholine-containing lipids, demonstrate the ability of this protein to interact non-ionically with lipid bilayers. The strong cross-linking of lipid bilayers suggests a role for basic protein in myelin, raising the possibility that the protein is instrumental in collapsing the oligodendrocyte cell membrane and thus initiating myelin formation.

Hydrogen-Ion Concentration↗
PubMed1977

Resuscitation from cardiopulmonary arrest during accidental hypothermia due to exhaustion and exposure.

A 16-year-old boy with accidental hypothermia and cardiopulmonary arrest due to exhaustion and exposure was resuscitated after warming measures -- hot wet towels, hot water bottles, and hot water enemas and gastric lavage -- had increased his rectal temperature from 25.2 to 28.0 degrees C. Despite prolonged cardiopulmonary arrest, recovery was almost complete, with no evident cerebral damage. Cardiopulmonary resuscitation procedures should not be abandoned until the body temperature is more than 30 degrees C, because the prognosis in cases of accidental hypothermia without associated disease is excellent if cardiac function can be re-established.

Adolescent↗
PubMed1977

Altered relation of two collagen types in osteogenesis imperfecta.

To ascertain if the features of osteogenesis imperfecta could be due to an abnormality in two genetically distinct collagens, Type III and Type I, we measured, in pepsin digests of skin, the ratio of the alpha 1, (III) to alpha 1 (I) chains derived from the two types, using a method of interrupted polyacrylamide-gel electrophoresis. In 40 control subjects this ratio decreased from about 0.45 in early fetal life to a mean (+/-2 S.D.) of 0.14 +/- 0.06 in 14 adults. Seven of nine adult patients with mild osteogenesis imperfecta had ratios of more than 4 S.D., above this mean, as did two of five patients with severe osteogenesis imperfecta. The increased ratio was probably due to a reduction of Type I collagen. If this reduction were generalized it could contribute to the bony fragility of osteogenesis imperfecta, since mineralized bone contains Type I collagen only.

Adult↗
PubMed1977

The secondary structure of myelin basic protein extracted by deoxycholate.

Because of the implication of myelin basic protein in some neurological diseases its in vivo structure is of particular interest. The protein is usually isolated using organic solvents and acid solutions and has previously been shown to contain little alpha-helical or beta-structure; but it is not known how the extraction methods influence the structure. Following recent observations that deoxycholate generally causes minimal structural perturbation when used to dissolve membrane proteins, this detergent has been used to extract the basic protein from bovine myelin. The protein contained in deoxycholate washes of myelin has been purified by gel chromatography and its secondary structure examined by circular dichroism spectroscopy. This protein and conventionally prepared bovine and human basic protein to which 1% deoxycholate has been added appear to have the same structure: they contain 8-14% more helical structure than the chloroform/methanol-extracted protein in pH 4.8 acetate buffer or in pH 9.15 Tris buffer. This conformational change is unaffected by addition of 0.25 M NaCl. The helical content will approach the upper limit if, as is expected, these ordered segments are short. It is suggested that basic protein may adopt this more ordered structure in myelin and possess activity not apparent in its water-soluble unordered conformation. Retention of its encephalitogenic activity following severe treatment may result from an ability to rapidly refold to the original conformation rather than from this activity being inherent in the unordered form.

Animals↗
PubMed1977

Protein turnover in patients before and after elective orthopaedic operations.

Whole body protein turnover was measured in 11 patients before and after elective orthopaedic operations be giving 15N-glycine orally every 4 hours for 32 hours. The patients were maintained throughout on a constant protein intake. In 2 control subjects a comparison was made between intermittent dosage and continuous infusion of 15N-glycine for the estimation of total protein turnover. With intermittent dosage the 15N abundance in urinary urea reached a constant level after about 24 hours. Rates of total protein synthesis and breakdown were calculated from the 15N abundance at the plateau level. After surgery there was a moderate increase in urinary N output. The apparent N balance (intake--urinary N) was -0-52 +/- 1-31 g/d (mean +/- s.d.) before operation and -7-51 +/- 4-5 g/d after operation. The rate of protein synthesis fell from 3-83 +/- 0-73 g kg-1 d-1 before operation to 2-94 +/- 0-83 g kg-1 d-1 after operation. This difference is statistically significant (0-05 greater than P greater than 0-01). There was no significant change in the rate of protein breakdown. The possibility remains that a block in protein synthesis, probably mainly in muscle, may be partly responsible for the so-called 'catabolic' loss of nitrogen after injury, but this has not been proved.

Adult↗
PubMed1977

Muscle-protein catabolism after injury in man, as measured by urinary excretion of 3-methylhistidine.

1. Urinary excretion of 3-methylhistidine, an index of the rate of muscle breakdown, has been measured during the first 7 days in patients after elective surgery or accidental injury. 2. There was no major difference between the mean daily excretion after skin grafting or total hip replacement, or in injured patients who were hyperketonaemic for the first 24 h after admission. 3. The group of injured patients who did not develop hyperketonaemia had a mean urinary 3-methylhistidine excretion which was twice that of the other groups. 4. It is concluded that increased breakdown of muscle protein makes a major contribution to the greater urinary nitrogen excretion in the normoketonaemic group of injured patients.

Adolescent↗