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Biomedical subjects

M Smith

Publications and source records attributed to M Smith.

At least 1,387 records · Page 77Linked to original sources
PubMed1975

Malignant mesenchymoma. Case report with electron microscopic study.

A malignant tumor from the thigh of a 65-year-old man was examined by light and electron microscopy. The tumor was diagnosed by light microscopy as malignant mesenchymoma with prevalence of leiomyosarcomatous or liposarcomatous components, but electron microscopic study revealed that the basic cell was similar to chondroblastic or osteoblastic cells. However, a precise ultrastructural classification of the tumor cells was not possible, since the majority of the cells had mixed features. The histogenesis, differentiation, and relation to prognosis are discussed.

Aged↗
PubMed1975

An organized distribution of acrosomal proteinase in rabbit sperm acrosomes.

Acrosomal proteinase was found to be present in a highly organized distribution within the acrosomes of rabbit spermatozoa by cytochemistry. This distribution consists of at least six linear loops of evenly spaced proteinase granules, which run diagonally across the flat side of the sperm head in a crisscrossing pattern with the two most anterior loops surrounding the region of the acrosome reaction. This is the first description of an organized distribution of enzymes within a lysosome-like organelle.

Acrosome↗
PubMed1975

Leucocyte proteinase activity and acute multiple sclerosis.

Increased leucocyte neutral proteinase activity is associated with an attack of multiple sclerosis. Raised neutral proteinase is found in other diseases with rapid destruction of neural tissues. Increased enzyme activity may be responsible for removing antigenic protein from the blood.

Humans↗
PubMed1975

Nucleotide sequence of salmon testes and salmon liver cytoplasmic initiator tRNA.

Initiator tRNAs from the cytoplasm of salmon testes and salmon liver have been purified. The nucleotide sequence of these initiator tRNAs has been determined and found identical to that of initiator tRNA from mammalian cytoplasm. The only difference is the extent of modification of the nuceloside located between the dihydrouridine and the anticodon stems. In the salmon tRNAs, this modified nucleoside is predominantly N2N2-dimethyl guanosine, whereas in the mammalian initiator tRNA it is N2-methyl guanosine.

Animals↗
PubMed1975

The organized distribution of acrosomal proteinase within the acrosomes of rabbit spermatozoa.

Acrosomal proteinase was found to be present in a highly organized distribution in the acrosomes of rabbit spermatozoa, using cytochemistry. This distribution consists of at least six linear loops of evenly spaced proteinase granules, which run diagonally across the flat side of the sperm head in a criss-crossing pattern. Two additional loops may be present, one encircling the tip of the spermatozoon in the region of the acrosome reaction, and the other at the posterior end of the acrosome. The results also seem to indicate that the enzyme granules are associated with the outer, and not the inner, acrosomal membrane.

Acrosin↗
PubMed1975

The synthesis of the internucleotide (phosphodiester) bond by a base-catalysed reaction.

Potassium tert-butoxide in hexamethyl phosphoramide and dimethyl formamide provides an excellent catalyst for the reaction of a 3'-hydroxyl or a 5'-hydroxyl group of a nucleoside with an appropriate nucleoside phosphorofluoridate to yield the dinucleoside phosphate. This paper describes the experiments leading to the development of this reaction together with the synthesis of thymidylyl-(5' leads to 3')-thymidine (dT-dT).

Methods↗
PubMed1975

Application of base-catalysed reaction to the synthesis of dinucleotides containing the four common deoxyribonucleosides and of oligodeoxythymidylates.

The phosphorylation of nucleosides by a nucleoside phosphorofluoridate in the presence of potassium tert-butoxide is a very effective reaction for internucleotide bond synthesis in the case of pyrimidine deoxynucleosides. However, for the purine deoxynucleosides, yields are reduced due to competing reactions. The method was applied to the stepwise synthesis of oligothymidylates. The yield of the trinucleotide was good whereas that of the tetranucleotide was reduced due to the insolubility of the intermediate trinucleotide in the presence of potassium tert-butoxide.

Fluorides↗
PubMed1975

Reaction of a nucleoside 2, 4-dinitrophenyl phosphate with fluoride; a convenient method for the preparation of the nucleoside phosphorfluoridate.

Examination of the reaction of 2, 4-dinitrofluorobenzene with thymidine-5' phosphate in detail reveals that the initial product is the 2, 4-dinitrophenyl ester. This reacts with fluoride to produce thymidine-5' phosphorfluoridate. This second reaction provides the basis for the conversion of preformed thymidine-5' 2, 4-dinitrophenyl phosphate to thymidine-5' phosphorofluoridate.

Binding Sites↗
PubMed1975

Enzymatic synthesis of oligonucleotides of defined sequence. Addition of short blocks of nucleotide residues to oligonucleotide primers.

Polynucleotide phosphorylase from Escherichia coli can be used to catalyse the addition of short tracts of deoxyadenylate residues to the 3'-termini of deoxyribooligonucleotides of the type pdAn-dN (where dN = dC, dT or dG) using dADP as donor. Similarly, the enzyme can also be used to catalyse the addition of short tracts of adenylate residues to the 3'-termini of ribooligonucleotides of the type An-N (where N = C, U or G) using ADP as donor. In the ribooligonucleotide series, phosphorolytic cleavage of the primer oligonucleotides is significant and results in the concommitant production of oligoadenylates lacking the N residue. Oligomers of the same length, with and without the residue N, were readily separated by thermal elution from cellulose-pdT9 columns. This latter procedure therefore provides a simple method for purification of the oligoadenylates containing an internal base substitution and it also provides a convenient assay for oligonucleotide phosphorolysis.

Adenine Nucleotides↗
PubMed1975

The base-pairing specificity of cellulose-pdT9.

The stability of the interaction of oligoadenylates, containing single nucleotide substitutions, with cellulose-pdT9 has been studied by thermal elution. In the case of oligodeoxyriboadenylates, the replacement of an internal dA by dC, dG or dT caused destabilization. In the case of oligoriboadenylates, replacement of an internal A residue by C or U resulted in a significantly lesser destabilization. The results indicate that caution should be exercised in extrapolation of data on the specificity of deoxyribonpolynucleotide-deoxyribopolynucleotide hybridization to structure of the type deoxyribopolynucleotide-ribopolynucleotide.

Adenine Nucleotides↗
PubMed1975

Insulinoma: aids to management.

Three cases of insulinoma seen in the past few months are reported in order to highlight recent advances in the management of this condition. These advances include serum insulin level determinations to correlate with blood sugar levels; selective arteriography as a means of localizing a tumour; and the monitoring of blood sugar levels during surgery.

Adenoma, Islet Cell↗
PubMed1975

Studies of the linkage relationship of beta-2-microglobulin in man-mouse somatic cell hybrids.

Beta-2-microglobulin (beta2mu) production has been studied in 33 primary man-mouse hybrid clones and in 26 secondary man-mouse hybrid clones. These clones have also been examined for the presence of 15 human enzyme phenotypes. Karyotypic analyses have been carried out on clones. From these studies the following conclusions can be drawn: (1) Gene(s) determining human beta2mu production in humans are apparently syntenic with the MPI gene on chromosome 15. (2) Long-term fibroblast lines may be of limited use in mapping studies as chromosomal rearrangements frequently occur in these lines. (3) The gene(s) determining beta2mu production in humans segregate independently of chromosome 6. If the assignment of the genes determining HL-A alloantigens to chromosome 6 is correct, our results imply that beta2mu and HL-A alloantigens are determined by genes carried on different chromosomes, despite the fact that beta2mu forms an integral part of the HL-A molecule.

Animals↗
PubMed1975

Depressed in vitro aggregation of platelets of chronic hemodialysis patients (CHDP): a role for cyclic AMP.

1) On log-log-coordiantes a direct correlation has bee shown to exist between plasma cyclic AMP and plasma Cr levels. 2) hemodialysis results in a significant reduction in the arterial plasma cyclic AMP levels, but a return of plasma cyclic AMP to pre-dialysis levels is seen within 30 mins post-dialysis. 3) the dialyzer clearance of cyclic AMP, both in vitro and vivo, is commensurate with its M.W. 4) In vitro platelet aggregation responses, to ADP, EPI, and COLL are not influenced by PRP cell counts between 150,000 and 300,000/mm3. 5) the BT of NC and CHDP are not significantly different, indicating that the in vivo hemostatic properties of the CHDP are otherwise intact. 6)the CHDP have PVPC significantly lower than the NC, a finding commensurate with the usual mold thrombocytopenia of renal failure. 7)the aggreation responses of the CHDP to COLL and to both Lo and Hi concentrations of ADP and EPI are significantly less than those of the NC. 8)A statistically significant inverse correlation between aggregation response and plasma cyclic AMP is observed.

Adenosine Diphosphate↗