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Biomedical subjects

M Little

Publications and source records attributed to M Little.

At least 181 records · Page 10Linked to original sources
PubMed1983

Role of the intensive care ambulance in the transport of accident victims.

The performance of intensive care ambulance officers (paramedics) has been assessed by an analysis of interventions and outcomes in 75 patients transported by ambulance services to the Westmead Centre following accidents. An injury severity score has been used to compare anticipated with actual results. It appeared that some 20% of patients benefited from paramedical interventions, that some 10% reached hospital alive because of the interventions, and that about 3% survived in the long term because of the interventions. Ambulance officers showed themselves to be accurate in assessing the severity of trauma.

Accidents, Traffic↗
PubMed1983

Identification and characterization of axopodial tubulins from Echinosphaerium nucleofilum.

Isolated microtubule protein from axopodia of the heliozoan Echinosphaerium nucleofilum, consisting of two major bands on SDS-polyacrylamide gel electrophoresis (SDS-PAGE), has been compared to axonemal and cytoplasmic tubulins from both animal and non-animal sources. The upper E. nucleofilum protein band migrated faster than the alpha-tubulins of bovine brain and sea anemone sperm tails but with approximately the same electrophoretic mobility as the axonemal alpha-tubulins of Tetrahymena pyriformis and the alga Chlorogonium elongatum and cytoplasmic alpha-tubulin from the slime mold Physarum polycephalum. The lower E. nucleofilum protein band, however, had a higher electrophoretic mobility than all the beta-tubulins which we have so far examined. It was, nevertheless, a true beta-tubulin as shown by its migration on two-dimensional gel electrophoresis and the general resemblance of its one- and two-dimensional peptide maps to those of other beta-tubulins. The Staphylococcus aureus protease cleavage pattern of the upper axopodial protein band was similar to those of other non-animal alpha-tubulins but quite different from those of the animal alpha-tubulins. In contrast, the two-dimensional tryptic peptide map of axopodial alpha-tubulin was distinct from all of them. For example, a characteristic constellation of peptides common to the peptide maps of the other alpha-tubulins was absent from that of E. nucleofilum. In contrast to Physarum and metazoan tubulins but similar to Tetrahymena tubulin, the axopodial alpha-tubulin had a more basic isoelectric point than the beta-subunit as shown by two dimensional gel electrophoresis. Some of the unusual characteristics of E. nucleofilum axopodial tubulin may not only reflect phylogenetic variation, but also the different functional requirements of axopodial microtubules.

Animals↗
PubMed1983

Tubulin amino acid sequence and consequences.

The 451 residues of alpha-tubulin from pig brain and the 445 residues of the beta-subunit display 41% sequence identity. Although the primary structure is highly conserved during evolution, several positions in each of the chains are heterogeneous, indicating four alpha-variants and two of the beta-polypeptide. Both C-terminal parts are highly acidic. Small regions can be correlated to sequences of nucleotide binding proteins. Cysteine beta 201 may be involved in the colchicine binding site.

Amino Acid Sequence↗
PubMed1982

beta 2-Tubulin, a form of chordate brain tubulin with lesser reactivity toward an assembly-inhibiting sulfhydryl-directed cross-linking reagent.

Beta 1 and beta 2 are the designations given to two forms of beta-tubulin that have different electrophoretic mobilities on discontinuous polyacrylamide gels in the presence of sodium dodecyl sulfate [Little, M. (1979) FEBS Lett. 108, 283-286]. Beta 1 and beta 2 constitute respectively 75% and 25% of the total beta-tubulin in bovine brain. Although beta 1 appears to be ubiquitous in animals, beta 2 has so far only been found in the brains of cows, pigs, deer, rats, chicks, and dogfish but not in squid brain. Beta 2 is not found in bovine kidneys, in porcine lungs, or in any nonchordate tubulin that has been examined. When tubulin is reacted with the sulfhydryl-directed reagent N,-N'-ethylenebis(iodoacetamide) (EBI), beta 1, but not beta 2, is converted to a faster moving form, beta. The yield of beta 2 in this reaction is not altered by the presence of drugs. When [14C]EBI is used as a probe, most of the label is incorporated into beta 1 rather than beta 2. Tubulin molecules that have reacted with EBI to form beta are much less likely to polymerize into microtubules than are molecules that have not formed beta. In view of the observation that only beta 1, and not beta 2, can form beta, it is possible that beta 1 represents a form of tubulin whose assembly may be regulated by a mechanism involving sulfhydryls. In contrast, beta 2 may represent a form of tubulin whose assembly is regulated by some other mechanism.

Animals↗
PubMed1981

Comparative structure and chemistry of tubulins from different eukaryotes.

Electrophoretic and peptide mapping have been used to examine alpha- and beta-tubulins from chordates, tunicates, echinoderms, mollusks, brachiopods, ferns, fungi, green algae and heliozoans. Cytoplasmic, ciliary, flagellar, and axopodial tubulins were examined. The results show that beta-tubulin is more conserved than alpha-tubulin. The large differences seen between axonemal and cytoplasmic tubulins and the similarity of all axonemal tubulins examined indicate that the genes for these two tubulin classes diverged prior to the appearance of metazoa and metaphyta. Comparisons of alpha-tubulins appear useful for tracing phyletic relationship within kingdoms whereas comparisons of beta-tubulins may be better for relating the kingdoms to each other.

Animals↗
PubMed1981

Tubulin sequence conservation.

Various aspects of the primary structure of tubulin are discussed and tubulin sequence data are compared. A hypothesis concerning the evolution of tubulin is also presented. The main points raised are: (1) Identical glycyl rich regions in alpha- and beta-tubulin, which are similar in both sequence and predicted secondary structure to a region in several nucleotide binding enzymes, may be involved in binding GTP. (2) Small regions of homology are present to actin, myosin and troponin T. These homologous regions may have the same function, resulting in a convergence of their sequences, or they may have arisen by a pathway of protein evolution which is still only very poorly understood. (3) The mutation rate between pig and chick brain tubulin is 0.22 PAMs (accepted point mutations/100 residues) per hundred million years, which is comparable to that of the histones. At an early time in its history, however, the tubulin heterodimer appears to have had a relatively high rate of mutation. This may have been during the evolution of the first eukaryotes.

Amino Acid Sequence↗
PubMed1981

Complete amino acid sequence of alpha-tubulin from porcine brain.

The amino acid sequence of alpha-tubulin from porcine brain was determined by automated and manual Edman degradation of eight sets of overlapping peptides. It comprises 450 residues plus a COOH-terminal tyrosine that is present only in 15% of the material. A region of 40 residues at the COOH-terminus is highly acidic, mainly due to 16 glutamyl residues. This high concentration of negative charge suggests a region for binding cations. At least six positions, most of them around position 270, are occupied by two amino acid residues each. Several of these exchange sites were assigned to specific peptides by analysis of the purified corresponding fragments. These data indicate four alpha-tubulins in porcine brain. Although alpha-tubulin on the whole is unrelated to other proteins, there are regions that can be correlated to sequences of the myosin head, to actin, to tropomyosin, and to troponins C and T.

Animals↗
PubMed1981

Complete amino acid sequence of beta-tubulin from porcine brain.

The primary structure of porcine brain beta-tubulin was determined by automated and manual Edman degradation of six sets of overlapping peptides. The protein consists of 445 amino acid residues and has a minimum of six positions that are heterogeneous, indicating at least two beta-tubulins in porcine brain. Comparison of the optimally aligned sequences of alpha-tubulin and beta-tubulin indicates that 41% of their primary structures are identical. A region rich in glycyl residues is similar both in sequence and predicted secondary structure to the phosphate binding loop of several nucleotide binding enzymes. beta-Tubulin contains a highly acidic COOH-terminal region that resembles the NH2-terminus of troponin T.

Amino Acid Sequence↗