PubMed Health⌕ Search

Biomedical subjects

B Asfaw

Publications and source records attributed to B Asfaw.

27 records · Page 2Linked to original sources
PubMed1991

Comparison of sialylation of maltase-glucoamylase in brush-border and soluble fractions of the small intestine of immature rats.

Two fractions of high-molar-mass soluble neutral maltase-glucoamylase (G1 and G2) of distal small intestine of 18-day-old rats separated on Sepharose 4B differ in sialylation which is reflected in their pI values obtained by chromatofocusing. The major soluble G1 fraction shows eight sialylated peaks converted by neuraminidase into a single fraction eluted at pH 4.21. Fraction G2 is less sialylated and neuraminidase causes its pI shift to 4.36. The chromatofocusing pattern suggests that G1 contains more acidic and G2 more basic glycoforms than their membrane-bound counterpart. Presence of less acidic pI values in the soluble G1 fraction of 18-day-old rats than in that of 13-day-old rats indicates that developmental decrease of sialylation concerns not only membrane-bound but also the soluble membrane-type of maltase-glucoamylase.

Animals↗
PubMed1988

The first identification of the benzenediazonium ion formation from a non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) by microsomes of rat livers.

1-Phenylazo-2-hydroxynaphthalene (Sudan I) is converted by microsomal enzymes of rat livers in vitro to 5 products. Hepatic microsomes from 5,6-benzoflavone-treated rats are more effective for the metabolism of Sudan I than those from phenobarbital- or Sudan I alone-treated rats. Major products formed by microsomes are identified as the ring-hydroxyderivatives of benzene and naphthalene rings. The formation of the benzenediazonium ion evolved by oxidative splitting of the azo group of Sudan I by microsomal enzymes is also proved. The oxidative splitting of Sudan I by microsomal enzymes may be considered as the possible mechanism of the Sudan I activation to the ultimate carcinogen (benzenediazonium ion).

Animals↗
PubMed1988

A new way to carcinogenicity of azo dyes: the benzenediazonium ion formed from a non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene(Sudan I) by microsomal enzymes binds to deoxyguanosine residues of DNA.

1-Phenylazo-2-hydroxynaphthalene (Sudan I) activated by pre-incubation with microsomal enzymes of rat livers covalently binds to DNA from calf thymus. Benzenediazonium ion formed from Sudan I by activation with microsomal enzymes is the principal active metabolite, which binds to DNA. Enzymatic hydrolysis of modified (14C-labelled) DNA, followed by separation of deoxynucleosides on a Sephadex G-10 column revealed that deoxyguanosine is the principal target for the binding of activated Sudan I. The high-performance liquid chromatographic (HPLC) analysis indicate that probably more than one radioactive adduct of activated Sudan I with deoxyguanosine is formed.

Animals↗
PubMed1988

Activation of carcinogens by peroxidase. Horseradish peroxidase-mediated formation of benzenediazonium ion from a non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) and its binding to DNA.

Horseradish peroxidase in the presence of hydrogen peroxide (HRP/H2O2) oxidizes a carcinogenic non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) to the ultimate carcinogen, which binds to calf thymus DNA. The principal product of Sudan I oxidation by the HRP/H2O2 system is the benzenediazonium ion. Minor products are hydroxy derivatives of Sudan I, in which the aromatic rings are hydroxylated. The principal oxidative product (the benzenediazonium ion) is responsible for the carcinogenicity of Sudan I, because this ion, formed from this azo dye, binds to DNA.

Animals↗
PubMed1985

Proximal femur articulation in Pliocene hominids.

The supposed "nonhuman anthropoid"-type femur head articular surface described for the Pliocene hominid specimen A.L.288-1 ("Lucy") by Stern and Susman in 1983 is present in significant numbers of modern human femora. This nonmetric skeletal trait was also found to be sex-related in modern human samples examined.

California↗
PubMed1983

A new hominid parietal from Bodo, Middle Awash Valley, Ethiopia.

A piece of left parietal of a Middle Pleistocene hominid, recovered from the Upper Bodo Sand Unit, in the Middle Awash, Ethiopia, is described anatomically and compared to Middle Pleistocene hominids and modern Homo sapiens. It bears several primitive features and has important implications for the original Bodo skull, found at the same stratigraphic level in the same area. The new fossil skull represents a different individual from the original Bodo skull.

Animals↗
PubMedDate not supplied

New partial skeleton of Homo habilis from Olduvai Gorge, Tanzania.

A new partial skeleton of an adult hominid from lower Bed I (about 1.8 Myr ago), Olduvai Gorge, is described. This specimen's craniodental anatomy indicates attribution to Homo habilis, but its postcranial anatomy, including small body size and relatively long arms, is strikingly similar to that of some early Australopithecus individuals.

Animals↗
PubMedDate not supplied

The earliest Acheulean from Konso-Gardula.

Konso-Gardula is a palaeoanthropological area discovered by the 1991 Palaeoanthropological Inventory of Ethiopia in the southern Main Ethiopian Rift. The Konso-Gardula sediments span the period about 1.3-1.9 million years ago. They contain rich Acheulean archaeological occurrences. Vertebrate fossils include early Homo.

Animals↗